Wastewater treatment method and equipment

Abstract

Aspects of the invention relate to a wastewater treatment method (100) and a wastewater treatment plant (1) for treating wastewater. The wastewater treatment method (100) includes receiving wastewater to be treated. The wastewater is supplied to a bioreactor (13) for biofiltration of the wastewater. The wastewater is discharged from the bioreactor (13) to a mechanical filtration device (15) arranged downstream of the bioreactor (13). The mechanical filtration device (15) comprises a static filtration pack (75) for filtering solid waste suspended in the wastewater. The static filter pack (75) contains a plurality of mechanical filter elements (71), each having one or more filter units (73). And discharging the treated wastewater.

Description

Technical Field

[0001] The present disclosure relates to wastewater treatment methods and apparatus. Various aspects of the present disclosure relate to wastewater treatment methods and wastewater treatment plants. The wastewater may, for example, comprise industrial wastewater and / or municipal wastewater. The wastewater treatment methods and apparatus may also be used to treat wastewater for water reuse. Background Art

[0002] It is known to use bioreactors to perform biological filtration on wastewater. A bioreactor may, for example, comprise a filter medium that supports a microbial community that acts to convert organic matter present in the wastewater, thereby performing biological filtration. A bioreactor may be configured to support aerobic or anaerobic microorganisms for biological filtration. The filter medium may comprise a plurality of biological filtration elements that may circulate within the bioreactor (a so-called moving bed bioreactor).

[0003] The inventors have recognized in the present case that the movement of the biological filter elements in the bioreactor can produce solid particles suspended in the wastewater. The movement of the biological filter elements can cause material to be dislodged, for example when the biological filter elements contact each other and / or contact the side walls of the bioreactor. The dislodged material may include clumps of accumulated waste and / or dead microorganisms filtered from the wastewater. The size of the solid particles dislodged may be relatively small, less than 5 μm in diameter. The inventors have determined that additional filtration can be performed to remove at least some of the solid particles discharged from the bioreactor. If the biological filter elements are in a static bed, such as in a submerged aerated bed, it has been recognized that material can fall off the surface of the biological filter elements. This can result in solid matter settling into the wastewater, for example in the form of suspended particles. Other forms of biological filtration may result in particles and waste being introduced into the wastewater.

[0004] It is an object of the present invention to address one or more disadvantages associated with the prior art. Summary of the Invention

[0005] Various aspects and embodiments of the present invention provide a wastewater treatment method and a wastewater treatment plant as described in the accompanying claims.

[0006] According to one aspect of the present invention, there is provided a wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0007] Receive wastewater for treatment;

[0008] supplying the wastewater to a bioreactor to perform biological filtration on the wastewater;

[0009] wastewater discharged from the bioreactor is supplied to a mechanical filtration apparatus disposed downstream of the bioreactor, wherein the mechanical filtration apparatus comprises a static filter pack for filtering solid waste suspended in the wastewater, the static filter pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filter cells; and

[0010] discharging treated wastewater.

[0011] The mechanical filtration apparatus comprises a plurality of mechanical filtration elements. The mechanical filtration elements form the static filter pack that mechanically filters the wastewater as it passes through the mechanical filtration apparatus. The mechanical filtration apparatus can comprise a filter tank forming a filtration chamber in which the mechanical filtration elements are disposed. The filter cell or each filter cell formed in each mechanical filtration element has an open cell structure. The wastewater can flow into the filter cell or each filter cell. The mechanical filtration is performed by facilitating the settling of particles in the filter cell or each filter cell.

[0012] The bioreactor can comprise a biological filtration medium for biologically filtering the wastewater. The biological filtration medium can comprise a plurality of biological filtration elements for supporting a population of microorganisms on a surface of the biological filtration medium to biologically filter the wastewater. The biological filtration elements can be circulated within the bioreactor, i.e. form a moving bed biological filter. Alternatively, the biological filtration elements can be static within the bioreactor, i.e. form a static bed biological filter. Other types of bioreactor can be contemplated. For example, the bioreactor can not comprise a biological filtration medium.

[0013] The static filter pack in the mechanical filtration apparatus can be operable to filter solid waste discharged from the bioreactor. The solid waste can be removed from a surface of the biological filtration elements in the bioreactor. The solid waste can be removed when the biological filtration elements in a moving bed contact each other. The solid waste can be removed when the biological filtration elements form a static bed biological filter. Other mechanical, hydraulic or biological processes can remove the solid waste from the biological filtration elements. The solid waste can be suspended in the wastewater discharged from the bioreactor.

[0014] The biofiltration element can be static within the bioreactor during biofiltration. Alternatively, the biofiltration element can be circulated within the bioreactor during biofiltration. Circulation of the biofiltration element can result in solid waste being removed from the biofiltration element and suspended in effluent wastewater being discharged from the bioreactor. The solid waste can include waste from the effluent wastewater and / or clumps of microorganisms separated from the biofiltration element.

[0015] The method can include supplying effluent wastewater to a first settling tank to settle solids. The first settling tank can be located upstream of the bioreactor; and supplying effluent wastewater from the first settling tank to the bioreactor.

[0016] The method can include supplying effluent wastewater from the bioreactor to a second settling tank to settle solids. The second settling tank can be located downstream of the bioreactor. Effluent wastewater from the settling tank can be supplied to the mechanical filtration device.

[0017] The method can include introducing pressurized air into the bioreactor to circulate the biofiltration media within the bioreactor. Alternatively, or additionally, a mechanical agitator can be provided to agitate the biofiltration media within the bioreactor.

[0018] The method can include periodically cleaning the mechanical filtration device to remove solid waste accumulated in the static filtration pack. Cleaning of the mechanical filtration device can include breaking the static filtration pack to remove solid waste accumulated in the mechanical filtration element.

[0019] A waste outlet can be opened to discharge accumulated waste from the mechanical filtration device. The accumulated waste can be discharged during a cleaning process. The method can include breaking the static filtration pack, for example during a cleaning operation. Optionally, a mechanical filtration device inlet for receiving effluent wastewater from the bioreactor and a mechanical filtration device outlet for discharging treated effluent wastewater from the mechanical filtration device can be opened.

[0020] The method can include introducing a pressurized fluid into the mechanical filtration device to break the static filtration pack. The fluid can be introduced at a pressure greater than atmospheric pressure. The fluid can be, for example, air or water. Alternatively, air can be drawn into the mechanical filtration device as liquid is evacuated from the mechanical filtration device. Air can be periodically introduced into the mechanical filtration device, for example during a cleaning operation to clean the mechanical filtration element. Alternatively, or additionally, a backwash liquid can be introduced into the mechanical filtration device to clean the mechanical filtration element.

[0021] The method can comprise opening a mechanical filtration apparatus waste outlet to discharge at least some accumulated solid waste from the mechanical filtration apparatus. At least some wastewater from the mechanical filtration apparatus can be discharged with the accumulated solid waste. At least some accumulated solid waste from the mechanical filtration apparatus can be recirculated through the biological reactor. The solid waste can be removed from the mechanical filtration element, for example from a surface of the mechanical filtration element and / or from one or more filter cells formed therein. At least some solid waste removed from the mechanical filtration element can be recirculated through the biological reactor and subjected to further biological treatment. The accumulated solid waste can be introduced directly to the biological reactor or upstream of the biological reactor. For example, the accumulated solid waste can be introduced to a settling tank upstream of the biological reactor.

[0022] The method can comprise causing material suspended in wastewater to coagulate. The method can comprise using an electrocoagulation unit to cause material suspended in wastewater to coagulate. The electrocoagulation unit can be located upstream of the mechanical filtration apparatus. The coagulated material can be suspended in wastewater introduced to the mechanical filtration apparatus.

[0023] The electrocoagulation unit can be located downstream of the biological reactor. The electrocoagulation unit can cause solid waste discharged from a biological reactor to coagulate. The solid waste can be removed from a surface of the biological filtration element disposed in the biological reactor.

[0024] Alternatively, or additionally, the electrocoagulation unit can be incorporated into the mechanical filtration apparatus. Solid material, typically particulate, can be coagulated inside the mechanical filtration apparatus, thereby helping to ensure that the coagulated solid material remains intact. The electrocoagulation unit can comprise one or more electrodes to support an electrochemical process. The one or more electrodes can be disposed inside the mechanical filtration apparatus, for example inside a filtration chamber in which the static filter pack is formed. The one or more electrodes can be at least partially surrounded by the mechanical filtration element forming the static filter pack. The one or more electrodes can be sacrificial. By coagulating solid material, typically particulate, in the mechanical filtration apparatus, decomposition or degradation of the coagulated material can be reduced. The at least one electrocoagulation unit can cause material to coagulate directly into the static filter pack.

[0025] The method can comprise introducing a coagulant into the wastewater. The coagulant can cause floc to form in the wastewater. The floc can comprise or consist of loosely aggregated particles or soft flakes. The coagulant can be introduced into the wastewater upstream of the mechanical filtration apparatus. Alternatively, or additionally, the coagulant can be introduced into the wastewater within the mechanical filtration apparatus. For example, the coagulant can be introduced into a filter chamber in the mechanical filtration apparatus in which the static filter pack is formed. The coagulant can be introduced directly into the filter chamber or can be introduced at an inlet to the filter chamber. A coagulating dosing system can be provided to deliver the coagulant. The coagulating dosing system can deliver a metered quantity of coagulant. The coagulant can be introduced in liquid or solid form, for example comprising particles or powder.

[0026] The coagulant can cause phosphate dissolved in the wastewater to be released from solution and form particles. The coagulant can be ferric chloride or polyaluminium chloride (PAC). The coagulant can cause particles comprising or consisting of phosphate to coalesce. The coagulant can cause particles comprising or consisting of phosphate to coalesce and form floc. At least some of the floc can be suspended in the wastewater. The static filter pack of the mechanical filtration apparatus can filter at least some of the particles, floc and coalesced material from the wastewater.

[0027] In at least some embodiments, the flow of wastewater through the mechanical filtration apparatus is substantially constant. The method can comprise a single mechanical filtration of the wastewater in the mechanical filtration apparatus (i.e. the wastewater passes through the mechanical filtration apparatus once). Alternatively, the method can comprise multiple mechanical filtrations of the wastewater in the mechanical filtration apparatus (i.e. the wastewater passes through the mechanical filtration apparatus multiple times). A conduit can be provided to recirculate the wastewater through the mechanical filtration apparatus.

[0028] The method can comprise establishing a flow rate per unit cross-sectional area of the static filter pack formed in the mechanical filtration apparatus in the range 0.1 m3 / m2 / h to 19 m3 / m2 / h; 5 m3 / m2 / h to 19 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h.

[0029] According to another aspect of the application, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0030] an inlet for receiving wastewater to be treated;

[0031] a biological reactor comprising a biological filtration medium for biologically filtering the wastewater; and

[0032] a mechanical filtration apparatus disposed downstream of the bioreactor, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering solid waste suspended in the wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration cells; and

[0033] an outlet for discharging treated wastewater.

[0034] The mechanical filtration apparatus comprises a plurality of mechanical filtration elements. The mechanical filtration elements form the static filtration pack, which in use, mechanically filters the wastewater as it passes through the mechanical filtration apparatus. The mechanical filtration apparatus can comprise a filtration tank forming a filtration chamber, in which the mechanical filtration elements are disposed. The filtration cell or each filtration cell formed in each mechanical filtration element has an open cell structure. In use, the wastewater can flow into the filtration cell or each filtration cell. The mechanical filtration is carried out by promoting the settling of particles in the filtration cell or each filtration cell.

[0035] The bioreactor can comprise a biological filtration medium for biologically filtering the wastewater. The biological filtration medium can comprise a plurality of biological filtration elements for supporting a population of microorganisms on a surface of the biological filtration medium to biologically filter the wastewater. The biological filtration elements can be circulated within the bioreactor, i.e. form a moving bed biological filter. Alternatively, the biological filtration elements can be static within the bioreactor, i.e. form a static bed biological filter. Other types of bioreactor can be considered. For example, the bioreactor can not comprise a biological filtration medium.

[0036] In use, the static filtration pack in the mechanical filtration apparatus filters solid waste discharged from the bioreactor. The solid waste can be removed from the surface of the biological filtration elements in the bioreactor. The solid waste can be removed when the biological filtration elements in a moving bed contact each other. The solid waste can be removed when the biological filtration elements form a static bed biological filter. Other mechanical, hydraulic or biological methods can remove the solid waste from the biological filtration elements. The solid waste can be suspended in the wastewater discharged from the bioreactor.

[0037] The wastewater treatment plant can comprise a first settling tank for promoting the settling of solids suspended in the wastewater, the first settling tank being located upstream of the bioreactor.

[0038] Alternatively, or additionally, the wastewater treatment plant can include a second settling tank for promoting settling of solids suspended in the wastewater, the second settling tank being located downstream of the biological reactor. The second settling tank can be located between the biological reactor and the mechanical filtration device. Alternatively, the mechanical filtration device can be disposed inside the second settling tank. For example, the mechanical filtration device can be disposed near a downstream outlet of the second settling tank. When wastewater is discharged from the second settling tank, the wastewater can pass through the mechanical filtration device.

[0039] The wastewater treatment plant can optionally include a device for circulating the biological filtration elements within the biological reactor during filtration. The device can include a mechanical agitator disposed in the biological reactor. Alternatively, the device can include a pump for introducing pressurized liquid or air into the biological reactor. The pressurized liquid or air can circulate the biological filtration media within the biological reactor. In use, circulation of the biological filtration elements can cause solid waste to be removed from the biological filtration elements and suspended in wastewater discharged from the biological reactor. In one variant, the wastewater treatment plant can include a pump for introducing air into the biological reactor to form a (submerged) static bed biological filter comprising a plurality of biological filtration elements.

[0040] The wastewater treatment plant can optionally include a device for disrupting the static filtration pack in the mechanical filtration device to remove solid waste accumulated in the mechanical filtration elements. The device includes one or more of: a pump for introducing pressurized air into the static filtration pack; a pump for introducing pressurized liquid into the static filtration pack; a mechanical agitator for agitating the mechanical filtration elements.

[0041] The wastewater treatment plant can include one or more valves for closing at least one of the mechanical filtration device inlet and the mechanical filtration device outlet when the static filtration pack is disrupted.

[0042] The wastewater treatment plant can include a pump for supplying a pressurized fluid, such as water or air, to the mechanical filtration device to disrupt the static filtration pack. The wastewater treatment plant can include a mechanical filtration device waste outlet operable to discharge at least some solid waste accumulated in the mechanical filtration device. The mechanical filtration device waste outlet can be operable to discharge at least some solid waste removed from the mechanical filtration elements.

[0043] The wastewater treatment plant can include a backflow line configured to backflow at least some solid waste accumulated in the mechanical filtration device to the biological reactor. The backflow line can be configured to introduce waste to the biological reactor or upstream of the biological reactor. The backflow line can be connected to the biological reactor to directly backflow solid waste removed from the mechanical filtration element to the biological reactor. The backflow line can be connected to the first settling tank to backflow solid waste accumulated in the mechanical filtration device to the first settling tank.

[0044] The wastewater treatment plant can include at least one electrocoagulation unit to coagulate matter suspended in wastewater. The at least one electrocoagulation unit can be located upstream of the mechanical filtration device. In use, coagulated matter can be suspended in wastewater introduced to the mechanical filtration device. The at least one electrocoagulation unit can be located downstream of the biological reactor. In use, the at least one electrocoagulation unit can be operable to coagulate solid waste suspended in wastewater discharged from the biological reactor.

[0045] Alternatively, or additionally, the at least one electrocoagulation unit can be integrated into the mechanical filtration device. For example, the at least one electrocoagulation unit can be disposed within the filtration chamber, wherein the mechanical filtration elements form a static filtration pack within the filtration chamber. The at least one electrocoagulation unit can be at least partially surrounded by the mechanical filtration elements in the static filtration pack. The at least one electrocoagulation unit can coagulate matter directly into the static filtration pack.

[0046] The wastewater treatment plant can include at least one coagulant system to introduce a coagulant to wastewater upstream of the mechanical filtration device. The coagulant can cause floc to form in the wastewater. The floc can include or consist of loosely aggregated particles or soft flakes. In use, the coagulant can cause phosphate dissolved in the wastewater to precipitate from solution and form particles. The static filtration pack of the mechanical filtration device can be configured to filter particles or coagulated matter formed by the coagulant. The coagulant can be ferric chloride or polyaluminum chloride (PAC). Particles including or consisting of phosphate can coagulate. In use, particles including or consisting of phosphate can coagulate to form floc. At least some floc can be suspended in the wastewater. The static filtration pack of the mechanical filtration device is configured to filter floc from the wastewater.

[0047] In at least some embodiments, the wastewater flow through the mechanical filtration apparatus is substantially constant. The method can comprise a single mechanical filtration of the wastewater in the mechanical filtration apparatus (i.e. the wastewater passes through the mechanical filtration apparatus once). Alternatively, the method can comprise multiple mechanical filtrations of the wastewater in the mechanical filtration apparatus (i.e. the wastewater passes through the mechanical filtration apparatus multiple times). A conduit can be provided to recirculate the wastewater through the mechanical filtration apparatus.

[0048] The wastewater treatment plant can comprise at least one pump for pumping wastewater through the mechanical filtration apparatus. The at least one pump can be configured to establish a flow rate per unit cross-sectional area of the static filtration pack formed in the mechanical filtration apparatus in the range of 0.1 m3 / m2 / h to 19 m3 / m2 / h; 5 m3 / m2 / h to 19 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h.

[0049] According to an aspect of the present application, there is provided a wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0050] receiving wastewater to be treated;

[0051] supplying the wastewater to a biological reactor, the biological reactor comprising a biological filtration medium for biologically filtering the wastewater, the biological filtration medium comprising a plurality of biological filtration elements for supporting a community of microorganisms, wherein the biological filtration elements circulate within the biological reactor during filtration, the circulation of the biological filtration elements causing solid waste to be removed from the biological filtration elements and suspended in the wastewater;

[0052] supplying the wastewater discharged from the biological reactor to a mechanical filtration apparatus disposed downstream of the biological reactor, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering the solid waste removed from the biological filtration elements in the biological reactor and suspended in the wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0053] discharging treated wastewater.

[0054] It has been recognized that operation of a bioreactor produces solid waste, e.g., comprising or consisting of solid particles or floc. Floc can be discharged from the bioreactor. The solid waste is removed from the surface of the biofiltration media as the biofiltration media circulates within the bioreactor. In particular, the biofiltration media contact each other, causing the solid waste to be removed. The removed solid waste can be suspended in the wastewater discharged from the bioreactor, e.g., as solid particles. It has been determined that a mechanical filtration apparatus comprising a static filtration pack formed of a plurality of mechanical filtration elements is particularly effective at removing solid waste suspended in the wastewater discharged from a bioreactor. At least in certain embodiments, it has been determined that a combination of a bioreactor and a mechanical filtration apparatus in series is particularly effective in wastewater treatment. The wastewater can be, for example, industrial wastewater or municipal wastewater.

[0055] The bioreactor can be anaerobic or aerobic. An anaerobic bioreactor is configured to support anaerobic microorganisms. An aerobic bioreactor is configured to support aerobic microorganisms. For example, an aerobic bioreactor can be configured to introduce air into the wastewater to support aerobic microorganisms.

[0056] The mechanical filtration elements each have one or more filtration cells. The structure of the mechanical filtration elements is referred to herein as an open-cell structure. The filtration elements are non-porous. The sidewalls of each filtration cell are non-porous. The one or more filtration cells each comprise a hole formed in the mechanical filtration element. The filtration elements can be molded, for example, from a plastic material.

[0057] The cross-sectional area of the filtration cell or each filtration cell can be in the range of one (1) to ten (10) square millimeters; or one (1) to five (5) square millimeters. The length of the filtration cell can be greater than or equal to five (5) millimeters, six (6) millimeters, or eight (8) millimeters. The mechanical filtration elements can have negative buoyancy, neutral buoyancy, or positive buoyancy.

[0058] The wastewater treatment method can comprise supplying wastewater to a settling tank located upstream of the bioreactor to settle solids. Wastewater from the settling tank can be supplied to the bioreactor.

[0059] The wastewater treatment method can comprise introducing pressurized fluid into the bioreactor to circulate the biofiltration media within the bioreactor. The fluid can be a liquid or a gas. The wastewater treatment method can comprise introducing pressurized air into the bioreactor to circulate the biofiltration media within the bioreactor. Alternatively, or additionally, a mechanical agitator can be used to circulate the biofiltration media within the bioreactor. The mechanical agitator can comprise, for example, one or more rotating members.

[0060] The wastewater treatment method can include periodically cleaning the mechanical filtration apparatus to remove solid waste accumulated in the static filter pack. The cleaning of the mechanical filtration apparatus can include destroying the static filter pack to dislodge solid waste accumulated in the mechanical filtration element. The method can include destroying the static filter pack after at least one of closing a mechanical filtration apparatus inlet for receiving wastewater from the bioreactor; and a mechanical filtration apparatus outlet for discharging treated wastewater from the mechanical filtration apparatus. The cleaning can include destroying the static filter pack within a predetermined time period.

[0061] The static filter pack can be destroyed using one or more mechanical cleaning members. The one or more mechanical cleaning members can be driven by an electric motor or similar device. For example, the one or more mechanical cleaning members can be rotated within the mechanical filtration apparatus. Alternatively, or additionally, a fluid can be introduced into the mechanical filtration apparatus to destroy the static filter pack. The fluid can be a liquid or a gas. The fluid can be introduced at a pressure greater than atmospheric pressure. The fluid can be air. An air pump can be provided for supplying pressurized air to the mechanical filtration apparatus.

[0062] The wastewater treatment method can include opening a mechanical filtration apparatus waste outlet to discharge at least some wastewater and solid waste dislodged from the mechanical filtration element in the mechanical filtration apparatus. The mechanical filtration apparatus waste outlet can be opened after the static filter pack is destroyed within a predetermined time period.

[0063] The wastewater treatment method can include recirculating at least some wastewater through the bioreactor. At least some solid waste dislodged from the mechanical filtration element in the mechanical filtration apparatus can be reintroduced upstream of the bioreactor. Thus, solid waste accumulated in the mechanical filtration apparatus can be subjected to further biological filtration. The solid waste dislodged from the mechanical filtration element can be introduced directly into the bioreactor. Alternatively, the solid waste dislodged from the mechanical filtration element can be introduced upstream of the bioreactor, for example into a settling tank if present in the system.

[0064] The dislodged solid waste is preferably conveyed with the wastewater discharged from the mechanical filtration apparatus. Alternatively, or additionally, the dislodged solid waste can be conveyed with a separate liquid supply, for example a cleaning liquid.

[0065] The wastewater treatment method can include using an electrocoagulation unit to coagulate material suspended in the wastewater. The electrocoagulation unit can be located upstream of the mechanical filtration apparatus. The coagulated material can be suspended in the wastewater introduced into the mechanical filtration apparatus. At least in certain embodiments, the mechanical filtration apparatus is operable to remove the coagulated material from the wastewater.

[0066] The electrocoagulation unit can be located downstream of the bioreactor. The electrocoagulation unit can be operable to coagulate solid waste removed from the biofiltration elements in the bioreactor. Coagulated material can then be removed by the mechanical filtration apparatus.

[0067] According to another aspect of the application, there is provided a wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0068] receiving wastewater to be treated;

[0069] supplying the wastewater to a bioreactor, the bioreactor comprising a biofiltration medium for biofiltering the wastewater, the biofiltration medium comprising a plurality of biofiltration elements for supporting a population of microorganisms, wherein the biofiltration elements are circulated within the bioreactor during filtration, the circulation of the biofiltration elements resulting in solid waste being removed from the biofiltration elements and suspended in the wastewater;

[0070] supplying wastewater discharged from the bioreactor to an electrocoagulation unit to coagulate solid waste removed from the biofiltration elements in the bioreactor; and

[0071] discharging treated wastewater.

[0072] The microorganisms can be aerobic or anaerobic microorganisms. The biofiltration elements can be continuously circulated within the bioreactor to maintain appropriate environmental conditions to support the microorganisms in the bioreactor.

[0073] According to another aspect of the application, there is provided a wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0074] receiving wastewater to be treated;

[0075] supplying the wastewater to an electrocoagulation unit to coagulate solid material suspended in the wastewater;

[0076] supplying the wastewater from the electrocoagulation unit to a mechanical filtration apparatus, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering coagulated solid material from the electrocoagulation unit, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0077] discharging treated wastewater.

[0078] According to another aspect of the application, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0079] an inlet for receiving wastewater to be treated;

[0080] a bioreactor comprising a biofiltration medium for biofiltration of the wastewater, the biofiltration medium being suitable for supporting a community of microorganisms, the bioreactor comprising means for circulating the biofiltration medium within the bioreactor during filtration; and

[0081] a mechanical filtration apparatus disposed downstream of the bioreactor, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering solid waste removed from the biofiltration element in the bioreactor and suspended in the wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration cells; and

[0082] an outlet for discharge of treated wastewater.

[0083] The microorganisms can be aerobic, anaerobic or anoxic microorganisms.

[0084] The mechanical filtration elements each comprise one or more filtration cells. The mechanical filtration elements are non-porous. The side walls of each filtration cell are non-porous. The one or more filtration cells each comprise a hole formed in the mechanical filtration element. The mechanical filtration elements can be, for example, moulded from a plastics material.

[0085] The wastewater treatment plant can comprise a settling tank for promoting settling of solids suspended in the wastewater, the settling tank being located upstream of the bioreactor.

[0086] The wastewater treatment plant can comprise a supply of pressurised air for introduction of pressurised air into the bioreactor to circulate the biofiltration medium within the bioreactor. The wastewater treatment plant can comprise an air pump for generating the supply of pressurised air.

[0087] The wastewater treatment plant can comprise means for disrupting the static filtration pack in the mechanical filtration apparatus to dislodge solid waste accumulated in the open-cell filtration medium. The disruption means can comprise a mechanical member or agitator mechanism for disrupting the static filtration pack. Alternatively, or additionally, the disruption means can comprise a pump or compressor for supplying a pressurised fluid into the mechanical filtration apparatus. The fluid can comprise a liquid or a gas. The pump or compressor can supply pressurised air to the mechanical filtration apparatus.

[0088] The wastewater treatment plant can comprise one or more valves for closing at least one of: the mechanical filtration apparatus inlet; and the mechanical filtration apparatus outlet. At least one of the mechanical filtration apparatus inlet and / or the mechanical filtration apparatus outlet can be closed while the static filtration pack is being disrupted for cleaning.

[0089] The wastewater treatment plant can comprise a pump for introducing pressurised air or liquid into the mechanical filtration apparatus to disrupt the static filter packs. Alternatively, or additionally, the wastewater treatment plant can comprise a mechanical agitator for disrupting the static filter packs.

[0090] The wastewater treatment plant can comprise a mechanical filtration apparatus waste outlet operable to discharge at least some wastewater from the mechanical filtration apparatus.

[0091] The wastewater treatment plant can comprise a backflow line configured to backflow at least some wastewater and / or accumulated waste from the mechanical filtration apparatus for reintroduction into the wastewater treatment plant upstream of the biological reactor. The backflow line can be connected to the biological reactor to backflow wastewater and / or accumulated waste from the mechanical filtration apparatus into the biological reactor. The backflow line can be connected to a settling tank to backflow wastewater from the mechanical filtration apparatus into the settling tank upstream of the biological reactor. Water from the settling tank can then be discharged into the biological reactor.

[0092] The wastewater treatment plant can comprise an electrocoagulation unit to coagulate matter suspended in wastewater.

[0093] The electrocoagulation unit can be located upstream of the mechanical filtration apparatus. In use, coagulated matter is suspended in wastewater which is then introduced into the mechanical filtration apparatus.

[0094] The electrocoagulation unit can be located downstream of the biological reactor. In use, the electrocoagulation unit can be operable to coagulate solid waste suspended in wastewater discharged from the biological reactor.

[0095] According to another aspect of the application, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0096] an inlet for receiving wastewater to be treated;

[0097] a biological reactor comprising a biological filtration medium for biologically filtering the wastewater, the biological filtration medium being suitable for supporting a population of microorganisms, the biological reactor comprising means for circulating the biological filtration medium within the biological reactor during filtration; and

[0098] an electrocoagulation unit disposed downstream of the biological reactor, the electrocoagulation unit being configured to coagulate matter suspended in wastewater discharged from the biological reactor.

[0099] According to another aspect of the application, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0100] an inlet for receiving wastewater to be treated;

[0101] an electrocoagulation unit for coagulating solid matter suspended in the wastewater;

[0102] a mechanical filtration device arranged downstream of the electrocoagulation unit, wherein the mechanical filtration device comprises a static filtration pack for filtering coagulated solid matter discharged from the electrocoagulation unit and suspended in wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0103] an outlet for discharging treated wastewater.

[0104] It is expressly contemplated within the scope of this application that the various aspects, embodiments, examples, and alternatives set forth in the foregoing paragraphs, claims and / or the following description and drawings, in particular the various features thereof, can be employed alone or in any combination(s) thereof. That is, each of the embodiments and / or features of any embodiment can be employed in any combination or sub-combination unless such features are incompatible. Applicant reserves the right to change any originally claimed feature of the application or a corresponding structure thereof, if changed by an equivalent means, in its deposited web(s), or otherwise, while the claim remains adequately described in the claims. BRIEF DESCRIPTION OF DRAWINGS

[0105] One or more embodiments of the present application will now be described, by way of example only, with reference to the attached drawings in which:

[0106] Figure 1 a schematic view of a water treatment plant according to an embodiment of the application is shown;

[0107] Figure 2A a perspective view of a mechanical filtration element used in the filtration device of the water treatment plant shown; Figure 1 a perspective view of a variant of the mechanical filtration element shown;

[0108] Figure 2B a perspective view of a variant of the mechanical filtration element shown; Figure 2A an end view of the mechanical filtration element shown;

[0109] Figure 2C a perspective view of a variant of the mechanical filtration element shown; Figure 2A a perspective view of a variant of the mechanical filtration element shown;

[0110] Figure 3 a first flow diagram illustrating the operation of the wastewater treatment plant shown; Figure 1 a first flow diagram illustrating the operation of the wastewater treatment plant shown;

[0111] Figure 4 a schematic view of another embodiment of a water treatment plant according to the application is shown;

[0112] Figure 5 a schematic diagram of another embodiment of a water treatment plant according to the present invention is shown;

[0113] Figure 6 a schematic diagram of another embodiment of a water treatment plant according to the present invention is shown;

[0114] Figure 7 a schematic diagram of another embodiment of a water treatment plant according to the present invention is shown; Figure 6 a second flow diagram of the operation of the wastewater treatment plant shown;

[0115] Figure 8 a schematic diagram of another embodiment of a water treatment plant according to the present invention is shown, the water treatment plant comprising first and second chemical systems;

[0116] Figure 9 a schematic diagram of another embodiment of a water treatment plant according to the present invention is shown, the water treatment plant comprising three chemical systems;

[0117] Figure 10 shows an example of a filter tank suitable for use in a mechanical filtration apparatus according to the present invention. DETAILED DESCRIPTION

[0118] A method and apparatus for treating wastewater according to embodiments of the present invention are described herein with reference to the accompanying drawings. The wastewater in the embodiments is municipal wastewater. Alternatively or additionally, the wastewater treatment plant and wastewater treatment method can be used to treat industrial wastewater.

[0119] A wastewater treatment plant 1 according to embodiments of the present invention will now be described. The wastewater treatment plant 1 is a municipal wastewater treatment plant configured to clean municipal wastewater. As described herein, the wastewater treatment plant 1 employs physical and biological methods to clean the wastewater. The wastewater treatment plant 1 can also optionally use chemical methods to clean the wastewater. The wastewater treatment plant 1 cleans the wastewater to remove pollutants or toxins that, if released, can cause environmental degradation. The wastewater treatment plant 1 can also remove dissolved nutrients, such as nitrogen, to reduce or prevent waterway eutrophication. Nitrogen can be removed by a denitrification process to convert ammonia to nitrate. In certain embodiments, the wastewater treatment plant 1 can be used to treat industrial wastewater that is more toxic than municipal wastewater. The wastewater treatment plant 1 can include pre-treatment facilities (not shown) or post-treatment facilities, for example suitable for treating industrial wastewater to remove toxins.

[0120] As Figure 1As shown, the wastewater treatment plant 1 comprises a wastewater inlet 3; a wastewater outlet 5; and a waste outlet 7. The wastewater inlet 3 is configured to receive incoming wastewater. The wastewater outlet 5 is configured to discharge wastewater that has been treated by the wastewater treatment plant 1. The waste outlet 7 discharges waste that has been removed from the wastewater. The waste discharged from the wastewater treatment plant 1 through the waste outlet 7 can be subjected to further treatment. Alternatively, at least some of the waste can be recirculated through the wastewater treatment plant 1 for further treatment.

[0121] The wastewater treatment plant 1 comprises a settling tank 11, a biological reactor 13, a mechanical filtration device 15, and at least one air pump 17. The biological reactor 13 is provided to biologically filter the wastewater, as described herein. The biological reactor 13 in the present embodiment is a moving bed biological reactor, although other types of biological reactors are also contemplated. The mechanical filtration device 15 is provided to perform mechanical filtration to remove particles suspended in the wastewater discharged from the biological reactor 13. The settling tank 11, the biological reactor 13, and the mechanical filtration device 15 are connected in series. The wastewater is sequentially passed through the settling tank 11, the biological reactor 13, and the mechanical filtration device 15. In particular, the incoming wastewater is introduced into the settling tank 11 for primary settling. The wastewater discharged from the settling tank 11 is introduced into the biological reactor 13 for biological filtration. The wastewater discharged from the biological reactor 13 is introduced into the mechanical filtration device 15 for mechanical filtration. The wastewater is discharged from the wastewater treatment plant 1 after passing through the mechanical filtration device 15. One or more water pumps (not shown) can be provided to pump the wastewater through the wastewater treatment plant 1. At least one air pump 17 is provided to supply air to the biological reactor 13 and the mechanical filtration device 15 at a pressure greater than atmospheric pressure. In the present embodiment, the wastewater treatment plant 1 comprises a single air pump 17, and is provided with first and second control valves 19-1, 19-2 to control the supply of pressurized air to at least one of the biological reactor 13 and the mechanical filtration device 15, respectively. The wastewater treatment plant 1 comprises an electronic control unit ECU1 comprising at least one electronic processor 21 and system memory 23. The electronic control unit ECU1 is configured to control the operation of the wastewater treatment plant 1 in accordance with the methods described herein. The electronic control unit ECU1 is configured to control the operation of the first and second control valves 19-1, 19-2 to control the supply of pressurized air from the air pump 17 to the biological reactor 13 and the mechanical filtration device 15. In one variant, separate air pumps 17 can be provided to supply air to the biological reactor 13 and the mechanical filtration device 15, respectively.

[0122] The settling tank 11 comprises at least one settling tank inlet 31, at least one settling tank outlet 33, and at least one settling tank waste outlet 35. As Figure 1As shown in the figure, at least one settling tank inlet 31 and at least one settling tank outlet 33 are provided in the upper region of the settling tank 11. At least one settling tank waste outlet 35 is provided in the lower region of the settling tank 11. The settling tank inlet 31 is in fluid communication with the wastewater inlet 3 of the wastewater treatment plant 1. In use, the incoming wastewater is introduced into the settling tank 11 through the at least one settling tank inlet 31. Solid matter settles from the wastewater and sinks to the bottom of the settling tank 11. The wastewater is discharged from the settling tank 11 through the at least one settling tank outlet 33 to the biological reactor 13. The settling tank 11 thereby acts as a pre-filter for the biological reactor 13. At least one settling tank waste valve 37 is provided for controlling the discharge of solids and waste through the settling tank waste outlet 35. The waste discharged from the at least one settling tank 11 is typically in the form of sludge. The at least one settling tank waste valve 37 is selectively opened to discharge accumulated waste. The waste discharged from the at least one settling tank 11 is sent to disposal or further treatment. The ECU 1 is configured to control the operation of the at least one settling tank waste valve 37. A wastewater control valve (not shown) can optionally be provided to control the discharge of wastewater from the settling tank 11 through the at least one settling tank outlet 33.

[0123] The bioreactor 13 includes at least one bioreactor inlet 41, at least one bioreactor outlet 43, and at least one bioreactor air inlet 45. The at least one bioreactor inlet 41 is in fluid communication with the at least one settling tank outlet 33. In use, wastewater from the settling tank 11 is introduced into the bioreactor 13 through the at least one bioreactor inlet 41. The at least one bioreactor inlet 41 is located in the lower region of the bioreactor 13, and the at least one bioreactor outlet 43 is located in the upper region of the bioreactor 13. This arrangement is suitable for the bioreactor 13 of this embodiment, which establishes an upward flow of wastewater. If the bioreactor 13 is configured to establish a downward flow of wastewater, the relative positions of the at least one bioreactor inlet 41 and the at least one bioreactor outlet 43 can be reversed. The bioreactor 13 performs biological filtration of the wastewater. Specifically, the bioreactor 13 includes a biological filtration chamber 47 containing a biological filtration medium 49 for biological filtration of the wastewater. The biological filtration medium 49 includes a plurality of biological filtration elements 51. The inner and outer surfaces of the biological filtration elements 51 are adapted to support a microbial community. Microorganisms effectively transform organic matter present in the wastewater. In this embodiment, the open cell form of the biological filter element 51 provides an increased surface area for supporting microorganisms. The microorganisms in this embodiment are aerobic. In one variant, the bioreactor 13 can be configured to support anaerobic or anoxic microorganisms. A biofilm can form on the surface of the biological filter element 51. Other types of bioreactors 13 can be considered. For example, the bioreactor 13 can include a static bed bioreactor 13. The bioreactor 13 can, for example, include a submerged aeration filter (SAF). The biological filter element 51 forms a continuously aerated bed. The biological filter element 51 is at least substantially static in the bed. The biological filter element 51 can be held in place by one or more screens. The submerged aeration filter can include an integrated settling tank, for example, in the form of a settling chamber formed before the outlet of the submerged aeration filter. In one variant, the bioreactor 13 may not include a biological filter medium. For example, activated sludge from the downstream of the bioreactor 13 can be reintroduced into the bioreactor 13. The activated sludge can be introduced directly into the bioreactor 13 or upstream of the bioreactor 13 .

[0124] The bioreactor 13 is configured to promote biological treatment of wastewater. During filtration, the biological filter medium 49 is actively circulated within the biological filter chamber 47. The biological filter element 51 is continuously moved within the bioreactor 13 (a so-called moving bed bioreactor). Fluid can be introduced into the biological filter chamber 47 under pressure to circulate the biological filter medium 49. The circulation of the biological filter medium 49 is Figure 1The fluid can be a liquid or a gas. In the present embodiment, pressurized air is introduced into the biofiltration chamber 47 to circulate the biofiltration media 49 within the biofiltration chamber 47. The air pump 17 is configured to supply pressurized air to the at least one bioreactor air inlet 45. In one variant, a separate air pump can be provided to supply pressurized air to the bioreactor 13. The first control valve 19-1 is configured to control the supply of pressurized air to the at least one bioreactor air inlet 45. Alternatively, or additionally, a mechanical agitator, e.g., comprising one or more rotating members, can be provided to circulate the biofiltration media 49 within the biofiltration chamber 47. For example, if the bioreactor 13 is configured to support anaerobic microorganisms, it can be appropriate to use an agitator mechanism.

[0125] The bioreactor 13 comprises biofiltration media 49 comprising a plurality of biofiltration elements 51. The filtration media 49 typically occupies at least 30% (by volume) of the filtration chamber. The filtration media 49 can occupy 70% (by volume) of the filtration chamber. The filtration media 49 in the present embodiment occupies about 50% (by volume) of the filtration chamber. The biofiltration elements 51 support a population of microorganisms that break down waste. Influent enters the biofiltration chamber 47 for treatment. The biofiltration elements 51 act as a biological carrier that supports a population of microorganisms. The microorganisms typically form a biofilm on at least a portion of the surface of the biofiltration elements 51. An aeration grid (not shown) can be provided to introduce air into the biofiltration chamber 47. The aeration grid may, for example, comprise one or more tubular members having a plurality of holes through which air is introduced into the biofiltration chamber 47. In use, the air pump 17 can supply pressurized air to the aeration grid. The aeration grid is typically disposed in a lower portion of the biofiltration chamber 47. The air moves the biofiltration elements 51 within the biofiltration chamber 47 (forming a moving bed), thereby facilitating contact with waste. The introduction of air into the biofiltration chamber 47 also introduces oxygen into the biofiltration chamber 47 to facilitate aerobic activity. A screen (not shown) is provided on the bioreactor outlet 43 to retain the biofiltration elements 51 in the biofiltration chamber 47.

[0126] The biological filtration medium 49 is preferably continuously circulated within the biological filtration chamber 47 during filtration. It has been recognized that circulation of the biological filtration elements 49 within the biological filtration chamber 47 can cause solid matter to be removed from the biological filtration elements 49. Circulation of the biological filtration medium 49 causes the biological filtration elements 51 to contact one another, and this can cause solid matter to be removed from the surfaces of the biological filtration elements 51 or from within the open cells of the biological filtration elements 51. The solid matter removed from the biological filtration elements 51 can be in the form of flocs or flocculent masses. The removed solid matter can for example include flocs. The removed solid matter can include or consist of solid particles having a diameter of less than or equal to ten (10) micrometers (i.e. < 10 pm) and potentially less than or equal to five (5) micrometers (i.e. < 5 pm). The solid particles removed from the biological filtration elements 51 include suspended solid particles.

[0127] Following biological filtration, the wastewater is discharged from the biological reactor 13 through the at least one biological reactor outlet 43 and is introduced into the mechanical filtration apparatus 15. The mechanical filtration apparatus 15 is configured to perform mechanical filtration of the wastewater to remove at least some solid particles suspended in the wastewater discharged from the biological reactor 13. The mechanical filtration apparatus 15 includes a mechanical filtration tank 60, at least one mechanical filtration inlet 61, at least one mechanical filtration outlet 63, at least one mechanical filtration air inlet 65, and at least one mechanical filtration waste outlet 67. The at least one mechanical filtration inlet 61 is in fluid communication with the at least one biological reactor outlet 43. In use, wastewater from the biological reactor 13 is introduced into the mechanical filtration apparatus 15 through the at least one mechanical filtration inlet 61. The at least one mechanical filtration inlet 61 is disposed in a lower region of the mechanical filtration apparatus 15; and the at least one mechanical filtration outlet 63 is disposed in an upper region of the mechanical filtration apparatus 15. This arrangement is suitable for the mechanical filtration apparatus 15 in the present embodiment, in which an upward flow of wastewater is established. If the mechanical filtration apparatus 15 is configured to establish a downward flow of wastewater, the relative positions of the at least one mechanical filtration inlet 61 and the at least one mechanical filtration outlet 63 can be reversed. The mechanical filtration apparatus 15 performs mechanical filtration of the wastewater. In particular, the mechanical filtration apparatus 15 includes a mechanical filtration chamber 70 that includes a mechanical filtration medium 69 for performing mechanical filtration of the wastewater. The wastewater supplied to the mechanical filtration apparatus 15 is filtered by the mechanical filtration medium 69 to remove at least some solid particles suspended in the wastewater supplied from the biological reactor 13. The treated wastewater is discharged from the mechanical filtration apparatus 15 through the at least one mechanical filtration outlet 63.

[0128] The mechanical filtration medium 69 includes a plurality of mechanical filtration elements 71. The mechanical filtration elements 71 in the present embodiment include an open cell structure. Figure 2A and Figure 2BA schematic representation of one of the mechanical filter elements 71 is shown. Figure 2C A perspective view of a variant of one of the mechanical filter elements 71 is shown. Figure 2C The dimensions of the mechanical filter elements 71 are shown by way of example. The tolerance of the dimensions shown is ±1 mm. The inner wall thickness of the mechanical filter elements 71 is about 0.75 mm to 1 mm. A plurality of external ribs are formed around the outer periphery of the mechanical filter elements 71. The radial length of the ribs is about 0.5 mm to 1 mm. It will be appreciated that mechanical filter elements 71 having different dimensions can be used in the wastewater treatment plant 1 described herein. The mechanical filter elements 71 have a non-porous structure and each mechanical filter element contains one or more filter cells 73. The mechanical filter elements 71 include walls (internal and external) that form the one or more filter cells 73. The walls are impermeable and prevent the flow of liquid between adjacent filter cells 73. The one or more filter cells 73 each have a substantially uniform profile along the length of the mechanical filter element 71. The one or more filter cells 73 are open at each end. In the present embodiment, the filter cells 73 each have a cross-sectional area in the range of one (1) to five (5) square millimetres and a length greater than or equal to six (6) millimetres. A static filter pack 75 composed of the open- pore filter media 69 is formed within the mechanical filter chamber 70. The mechanical filter elements 71 in the present embodiment have a positive buoyancy in water. The mechanical filter elements 71 float in the wastewater in the mechanical filter chamber 70 and form the static filter pack 75 in the upper region of the mechanical filter chamber 70. In a variant, the mechanical filter elements 71 can have a negative buoyancy and can form the static filter pack 75 in the lower region of the mechanical filter chamber 70. The mechanical filter elements 71 effectively perform filtration by promoting the settling of solid particles suspended in the wastewater. The solid particles settle within the filter cells 73 and on the surface of the mechanical filter elements 71. In the present embodiment, the mechanical filter elements 71 are formed by extrusion moulding of a polymer. Other techniques can be used to form the mechanical filter elements 71.

[0129] The mechanical filter apparatus 15 is periodically cleaned to discharge the solids accumulated in the mechanical filter chamber. The cleaning of the mechanical filter apparatus 15 involves closing the at least one mechanical filter inlet 61 and the at least one mechanical filter outlet 63. The mechanical filter waste outlet 67 is closed during the cleaning operation and then opened to empty (or evacuate) the mechanical filter apparatus 15. In the present embodiment, a mechanical filter inlet valve 77 is provided for opening and closing the at least one mechanical filter inlet 61 and a mechanical filter outlet valve 79 is provided for opening and closing the at least one mechanical filter outlet 63. A mechanical filter waste valve 81 is provided for opening and closing the mechanical filter waste outlet 67. Both the mechanical filter inlet valve 77 and the mechanical filter outlet valve 79 are closed to close the mechanical filter inlet 61 and the mechanical filter outlet 63. The mechanical filter waste valve 81 is also closed to close the mechanical filter waste outlet 67.

[0130] The second control valve 19-2 is then opened to supply pressurized air into the mechanical filter chamber 70. The pressurized air is introduced into the mechanical filter chamber 70 and breaks up the static filter pack 75 and agitates the mechanical filter element 71. The mechanical filter apparatus 15 can be open to the atmosphere or a vent (not shown) can be opened. Accumulated waste is thereby removed from the mechanical filter element 71. The supply of pressurized air continues for a predetermined period of time. The period of time can be determined by methods such as empirical analysis. The mechanical filter waste valve 81 is then opened to open the mechanical filter waste outlet 67 and allow the discharge of waste water from the mechanical filter chamber 70. The supply of pressurized air can optionally continue after the mechanical filter waste outlet 67 is opened. A portion of the waste water discharged from the mechanical filter chamber 70 can be returned for further treatment within the waste water treatment plant 1. In the present embodiment, a waste return line 83 is provided for returning waste water discharged from the mechanical filter apparatus 15. A waste control valve 85 can optionally be provided to control the supply of waste water to the waste return line 83. In the present embodiment, a portion of the waste accumulated in the mechanical filter chamber 70 is returned to the settling basin 11 or the bioreactor 13. Thus, a portion of the waste can be recycled through the waste water treatment plant 1. A portion of the waste water discharged from the mechanical filter chamber 70 can optionally be sent to disposal or further treatment.

[0131] After the mechanical filter chamber 70 has been emptied, the mechanical filter waste valve 81 is closed to close the mechanical filter waste outlet 67. The supply of pressurized air to the mechanical filter chamber 70 is stopped by closing the second control valve 19-2. At least one of the mechanical filter inlet 61 and the mechanical filter outlet 63 are then opened to reestablish the flow of waste water through the mechanical filter apparatus 15.

[0132] In use, the mechanical filter element 71 forms a static filter pack 75 operable to filter solids from the wastewater. The mechanical filter element 71 can have positive buoyancy, negative buoyancy, or neutral buoyancy. The mechanical filter element 71 has an open-structured that provides high retention capacity. The flow rate per unit cross-sectional area of the static filter pack 75 can be less than 20 m3 / m2 / h (not including 20 m3 / m2 / h), such as in the range of 0.1 m3 / m2 / h to 19.9 m3 / m2 / h; 5 m3 / m2 / h to 19.5 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h. It has been recognized that these flow rates per unit cross-sectional area are particularly effective at removing floe (also known as flocculation clumps) from the wastewater. Floe comprises or consists of loosely aggregated particles or soft flakes. At least in certain embodiments, floe can settle within or outside the filtration cells 73 of the mechanical filter element 71. The relatively low flow rate through the static filter pack 75 helps to reduce or avoid breaking up the floe. Higher flow rates can potentially cause certain types of floe to break down or disintegrate into smaller floe or individual particles. At least in certain embodiments, the wastewater treatment plant 1 is able to capture very fine particles suspended in the wastewater. The treated water from the mechanical filter apparatus 15 can be discharged from the wastewater treatment plant 1 or sent to a receiving watercourse. Alternatively, the treated water can be sent downstream for further treatment.

[0133] Figure 3The first flowchart 100 shown illustrates the operation of the wastewater treatment plant 1 to treat wastewater. Wastewater to be treated is received by the wastewater treatment plant 1 as influent wastewater (block 105). Optionally, the wastewater is introduced into the primary settling tank 11 to facilitate settling of solids (block 110). Wastewater is discharged from the primary settling tank 11 to the biological reactor 13 (block 115). The biological reactor 13 biologically filters the wastewater, and biologically filtered water is discharged from the biological reactor (block 120). Movement of the biological filter elements causes the production of solid particles, which can comprise or consist of floc, that are introduced into the suspension of wastewater discharged from the biological reactor 13. Wastewater is supplied from the biological reactor 13 to the mechanical filtration device 15 (block 125). The wastewater discharged from the biological reactor 13 typically comprises particles suspended in the wastewater. The particles can clump together to form floc that is suspended in the wastewater. The floc can be formed from loosely clumped particles. The mechanical filtration device 15 mechanically filters the wastewater to remove at least some of the suspended solid particles (block 130). Treated wastewater (effluent) is discharged from the mechanical filtration device 15 (block 135). The mechanical filtration device 15 is periodically cleaned (block 140). The cleaning comprises breaking the static filter packs 75, for example by introducing a fluid such as air to disrupt the static filter packs 75 (block 145). Accumulated solid waste is removed from the static filter packs and discharged from the mechanical filtration device 15 (block 150). At least some of the solid waste from the mechanical filtration device 15 is back-flushed through the waste back-flush line 83 and again through the biological reactor 13 (block 155). The process continues (block 160).

[0134] The wastewater treatment plant 1 in the above-described embodiments has been described with reference to each of the primary settling tank 11, the biological reactor 13 and the mechanical filtration device 15. This is merely illustrative, and the wastewater treatment plant 1 can comprise more than one of each of the primary settling tank 11, the biological reactor 13 and the mechanical filtration device 15. For example, one or more biological reactors 13 can be provided. A plurality of biological reactors 13 can be provided, connected in parallel or in series. One or more primary settling tanks 11 can be provided upstream of the one or more biological reactors 13. A plurality of primary settling tanks 11 can be connected in parallel or in series upstream of the biological reactor 13. One or more tertiary settling tanks 20 can be provided downstream of the one or more biological reactors 13. A plurality of tertiary settling tanks 20 can be connected in parallel or in series downstream of the biological reactor 13. A pump (not shown) can be provided for pumping accumulated waste from the wastewater treatment plant 1, for example from the primary settling tank 11 and / or the tertiary settling tank 20.

[0135] The wastewater treatment plant 1 in the above examples is described with reference to a biological reactor 13 comprising a moving bed biological reactor (MBBR). Other types of biological reactors 13 can be considered for use in the wastewater treatment plant 1. The biological reactor 13 can be configured to perform aerobic, anaerobic or anoxic biological filtration of the wastewater. Aerobic biological filtration is performed by microorganisms (microbes) that require oxygen. Anaerobic biological filtration is performed by microorganisms (microbes) that require little or no oxygen (<0.5 mg / l or <0.2 mg / l). Anoxic biological filtration is performed by microorganisms (microbes) that release bound oxygen (nitrite / nitrate etc.) thereby reducing or avoiding the need to introduce air to aerate the wastewater.

[0136] As mentioned above, a portion of the accumulated waste can re-enter the biological reactor 13 in the form of activated sludge. Activated sludge contains a high concentration of microorganisms, including bacteria, protozoa and fungi, which exist in the form of loose aggregates of fine particles. The aggregates are kept in suspension by agitation (anaerobic systems) or with air (aerobic systems) with the aim of removing organic matter from the wastewater. The process is commonly referred to as return activated sludge (RAS).

[0137] The biological reactor 13 can comprise an integrated fixed-film activated sludge (IFAS). The process is similar to the moving bed biological reactor MBBR described herein. Activated sludge, for example accumulated in a tertiary settling tank, is introduced into a filter chamber comprising a filter medium. The filter medium and the activated sludge can both be present in the same filter chamber. The filter chamber can comprise an anoxic zone and an aerobic zone. The activated sludge can be introduced into the anoxic zone; and a moving bed biological reactor is established in the aerobic zone, for example by introducing air to agitate the filter medium.

[0138] The biological reactor 13 can comprise a sequencing batch reactor (SBR) which uses aerobic and anaerobic processes in a time sequence. The SBR can perform nitrification and denitrification. A steady and constant inflow is supplied to the filter chamber. The filter chamber is aerated to promote aerobic reactions. The supply of air is then stopped to promote settling. The water in the filter chamber is then decanted as an effluent. The remaining waste in the filter chamber is then discharged to waste. The process can be used with a chemical flocculant to remove phosphates. Additional biological treatment can be performed on the wastewater discharged from the filter tank.

[0139] The biological reactor 13 can comprise a membrane biological reactor (MBR). A membrane biological reactor combines a biological treatment process with membrane filtration. In an MBR system, organic matter in the wastewater is broken down by microorganisms. The treated water is then passed through a membrane filter to remove any remaining suspended solids and microorganisms. In this way, a highly treated effluent can be reused or discharged to the environment.

[0140] The bioreactor 13 can comprise a submerged aerated filter (SAF). The biological filtration elements can be held in a static bed submerged in the wastewater. The biological filtration elements are aerated to promote aerobic biological filtration.

[0141] Other types of mechanical and / or biological filtration of the wastewater can be performed. For example, the wastewater can be filtered using (i) dissolved air flotation (DAF), which brings particles to the surface of the water to promote removal, for example, by overflow; or (ii) a lamella separator in the form of inclined plates, which slows the flow of liquid and promotes the settling of particles for collection and removal by a sludge pump.

[0142] A mechanical filtration device 15 of the type 1 described herein can be provided upstream of the bioreactor 13. For example, the mechanical filtration device 15 can be provided between the primary settling tank 11 and the bioreactor 13.

[0143] Reference will now be made to Figure 4 Variations of the wastewater treatment plant 1 according to the above-described embodiments will now be described. Like reference numerals are used for like components. The present description focuses on the differences between the wastewater treatment plant 1 according to embodiments of the present application and the wastewater treatment plant 1 described with reference to Figure 1 the above-described embodiments.

[0144] The wastewater treatment plant 1 comprises a primary settling tank 11, a bioreactor 13, and a mechanical filtration device 15. The wastewater treatment plant 1 can optionally comprise a tertiary settling tank 20. The tertiary settling tank 20 can be provided between the bioreactor 13 and the mechanical filtration device 15. The wastewater treatment plant 1 further comprises a primary screen 9 provided upstream of the primary settling tank 11. The primary screen 9 is configured to filter relatively large debris and detritus from the inflow supplied to the wastewater treatment plant 1. The primary screen 9 comprises a plurality of holes through which the wastewater passes to remove the debris. For example, the primary screen 9 can comprise a screen, a mesh, or a membrane. The wastewater, after being filtered by the primary screen 9, is introduced into the primary settling tank 11. At least some of the debris that passes through the primary screen 9 settles out of suspension in the primary settling tank 11. The waste that accumulates in the primary settling tank 11 is discharged to waste through a primary settling tank waste outlet 11a. A valve (indicated by the valve symbol) can be provided on the primary settling tank waste outlet 11a.

[0145] The bioreactor 13 can comprise a moving bed bioreactor (MBBR) of the type described herein. In the present embodiment, the bioreactor 13 comprises a static bed bioreactor 13. The bioreactor 13 may, for example, comprise a submerged aerated filter (SAF). The biofiltration elements 51 form a continuously aerated bed. The biofiltration elements 51 are at least substantially static in the bed. The biofiltration elements 51 can be held in place by one or more screens. The submerged aerated filter can comprise an integrated settling tank, for example in the form of a settling chamber formed prior to the outlet of the submerged aerated filter. In a variant, the bioreactor 13 can not comprise biofiltration media. For example, activated sludge from downstream of the bioreactor 13 can be reintroduced into the bioreactor 13. The activated sludge can be introduced directly into the bioreactor 13 or upstream of the bioreactor 13. Other types of bioreactor 13 can be contemplated.

[0146] The mechanical filtration device 15 is configured to perform mechanical filtration of the wastewater to remove at least some of the solid particles suspended in the wastewater discharged from the bioreactor 13. The mechanical filtration device 15 comprises a mechanical filtration tank 60, at least one mechanical filtration inlet 61, at least one mechanical filtration outlet 63, at least one mechanical filtration air inlet 65, and at least one mechanical filtration waste outlet 67. The at least one mechanical filtration inlet 61 is in fluid communication with the at least one bioreactor outlet 43. In use, wastewater from the bioreactor 13 is introduced into the mechanical filtration device 15 through the at least one mechanical filtration inlet 61. The at least one mechanical filtration inlet 61 is preferably provided in a lower region of the mechanical filtration device 15; and the at least one mechanical filtration outlet 63 is preferably provided in an upper region of the mechanical filtration device 15. The mechanical filtration device 15 filters the wastewater supplied from the bioreactor 13. The mechanical filtration chamber 70 comprises a mechanical filtration media 69 for performing mechanical filtration of the wastewater. The mechanical filtration media 69 comprises a plurality of mechanical filtration elements 71 of the type described herein. The mechanical filtration elements 71 form a static filtration pack 75 which is adapted to filter particles and matter suspended in the water as the water flows through the mechanical filtration device 15. The mechanical filtration elements 71 have an open structure to facilitate settling of the suspended particles in the static filtration pack 75. The mechanical filtration elements 71 each have one or more filtration units 73. The wastewater is filtered by the mechanical filtration media 69 to remove at least some of the solid particles suspended in the wastewater supplied from the bioreactor 13. The treated wastewater (effluent) is discharged from the mechanical filtration device 15 through the at least one mechanical filtration outlet 63.

[0147] The mechanical filtration apparatus 15 is periodically cleaned to remove solids that have accumulated in the mechanical filtration chamber 70. Cleaning of the mechanical filtration apparatus 15 can include closing at least one mechanical filtration inlet 61 and / or at least one mechanical filtration outlet 63. The mechanical filtration waste outlet 67 is closed during filtration operations; and is opened during cleaning operations to empty (or evacuate) the mechanical filtration tank 60. An air supply conduit is provided to supply air to the air inlet 65, which enters the mechanical filtration chamber 70. Air introduced into the mechanical filtration chamber 70 agitates the mechanical filtration elements 71, breaking up static filtration packs. By agitating the mechanical filtration elements 71, waste and debris that has accumulated in one or more filtration cells 73 formed in the mechanical filtration elements 71 is dislodged. The dislodged waste can be removed to waste through the mechanical filtration waste outlet 67. Air can be pumped into the mechanical filtration tank 60 by an air pump (not shown) to agitate the mechanical filtration elements 71 during cleaning operations. Alternatively, or additionally, air can be drawn into the mechanical filtration chamber 70 through the air supply conduit. A one-way valve can be provided on the air supply conduit. When the mechanical filtration waste outlet 67 is opened, water in the mechanical filtration chamber 70 can be evacuated, resulting in a reduced pressure in the mechanical filtration chamber 70. The reduced pressure can cause air to be drawn into the mechanical filtration chamber 70 through the air supply conduit. As the mechanical filtration tank 60 is evacuated, air is drawn into the lower portion of the mechanical filtration chamber 70 and agitates the mechanical filtration elements 71. Other techniques can be employed to clean the mechanical filtration apparatus 15. For example, the mechanical filtration elements 71 can be back-flushed to dislodge retained debris. A back-flush liquid, such as water, can be introduced into the mechanical filtration chamber 70 to clean the mechanical filtration elements 71. The back-flush liquid can be removed to waste. Alternatively, at least some of the back-flush liquid can be returned to the wastewater treatment plant 1 for further treatment. For example, the back-flush liquid can be introduced into the biological reactor 13. In each embodiment of the wastewater treatment plant 1 described herein, the same cleaning process can be used to clean the mechanical filtration apparatus 15.

[0148] A portion of the wastewater removed from the mechanical filtration chamber 70 can be returned for further treatment within the wastewater treatment plant 1. In the present embodiment, a waste return line 83 is provided for returning wastewater removed from the mechanical filtration apparatus 15. A waste control valve 85 can optionally be provided to control the supply of waste to the waste return line 83. In the present embodiment, a portion of the waste from the mechanical filtration chamber 70 is returned to the biological reactor 13. The waste returned from the mechanical filtration apparatus 15 is typically in the form of sludge (comprising or consisting of settled solid matter). The waste can be introduced into the biological reactor 13 through the biological reactor inlet 41 or a separate inlet. At least some of the waste is thereby recirculated through the biological reactor 13 and the mechanical filtration apparatus 15. A portion of the waste removed from the mechanical filtration chamber 70 can be sent to waste or further treatment downstream of the wastewater treatment plant 1.

[0149] In use, the mechanical filter element 71 forms a static filter bag 75, which is operable to filter solids from wastewater. The mechanical filter element 71 can have positive buoyancy, negative buoyancy or neutral buoyancy. The mechanical filter element 71 has an open-pore structure that provides high retention capacity. The flow rate per unit cross-sectional area of ​​the static filter bag 75 can be less than 20m3 / m2 / h (excluding 20m3 / m2 / h), for example, in the range of 0.1m3 / m2 / h to 19.9m3 / m2 / h; 5m3 / m2 / h to 19.5m3 / m2 / h; or 11m3 / m2 / h to 19m3 / m2 / h. It has been recognized that these flow rates per unit cross-sectional area are particularly effective for removing flocs (also referred to as flocculent clumps) from wastewater. Flocs include loosely aggregated particles or soft flakes, or are composed thereof. At least in certain embodiments, flocs can be settled in or outside the filter unit 73 of the mechanical filter element 71. The relatively low flow rate through the static filter pack 75 helps to reduce or avoid the destruction of flocs. Higher flow rates can potentially cause certain types of flocs to break down or disintegrate into smaller flocs or individual particles. At least in certain embodiments, the wastewater treatment plant 1 is capable of capturing very fine particles suspended in the wastewater. The treated water from the mechanical filter device 15 can be discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water can be sent downstream for further treatment.

[0150] Now refer to Figure 5 Description based on Figure 4 Another variation of the wastewater treatment plant 1 of the embodiment shown. The same reference numerals are used for the same components. This description focuses on the wastewater treatment plant 1 according to this embodiment and the reference numerals. Figure 4 Differences between the described embodiments.

[0151] Bioreactor 13 can be a moving bed bioreactor or a static bed bioreactor. For example, bioreactor 13 can include a submerged aeration filter (SAF). In this embodiment, bioreactor 13 does not include a biological filtration element. Bioreactor 13 can be an activated sludge bioreactor. Other types of bioreactors 13 are contemplated.

[0152] In this embodiment, the wastewater treatment plant 1 includes at least one tertiary sedimentation tank 111. The tertiary sedimentation tank 111 is arranged downstream of the bioreactor 13 and upstream of the mechanical filtration device 15. The tertiary sedimentation tank 111 includes at least one tertiary sedimentation tank inlet 131, which is in fluid communication with at least one bioreactor outlet 43. In use, wastewater from the bioreactor 13 is introduced into the tertiary sedimentation tank 111. The tertiary sedimentation tank 111 includes at least one tertiary sedimentation tank outlet 133 and at least one tertiary sedimentation tank waste outlet 135. Figure 5As shown, at least one tertiary settling basin inlet 131 and at least one tertiary settling basin outlet 133 are provided in an upper region of the tertiary settling basin 111. At least one tertiary settling basin waste outlet 135 is provided in a lower region of the tertiary settling basin 111. In use, water treated by the biological reactor 13 enters the tertiary settling basin 111 through the at least one tertiary settling basin inlet 131. Solid matter settles out of the wastewater and sinks to the bottom of the tertiary settling basin 111. The wastewater is discharged from the tertiary settling basin 111 through the at least one tertiary settling basin outlet 133 to the mechanical filtration device 15. At least one settling basin waste valve 137 is provided for controlling the discharge of solids and waste through the tertiary settling basin waste outlet 35. The waste discharged from the at least one settling basin 11 is typically in the form of sludge. The at least one settling basin waste valve 37 is selectively opened to discharge accumulated waste. The waste discharged from the at least one tertiary settling basin 111 can be sent to waste or for further treatment. A portion of the waste discharged from the at least one tertiary settling basin 111 can be recirculated to the biological reactor 13 for treatment. A wastewater control valve (not shown) can optionally be provided to control the discharge of wastewater from the tertiary settling basin 111 through the at least one settling basin outlet 33.

[0153] In use, the mechanical filtration elements 71 form a static filter pack 75 that is operable to filter solids from the wastewater. The mechanical filtration elements 71 can have a positive buoyancy, a negative buoyancy, or a neutral buoyancy. The mechanical filtration elements 71 have an open-structured configuration that provides a high retention capacity. The flow rate per unit cross-sectional area of the static filter pack 75 can be less than 20 m3 / m2 / h (not including 20 m3 / m2 / h), such as in a range from 0.1 m3 / m2 / h to 19.9 m3 / m2 / h; 5 m3 / m2 / h to 19.5 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h. It has been recognized that these flow rates per unit cross-sectional area are particularly effective at removing floe (also referred to as flocculation clumps) from the wastewater. Floe comprises or consists of loosely aggregated particles or soft flakes. In at least some embodiments, floe can settle within or outside of the filtration cells 73 of the mechanical filtration elements 71. The relatively low flow rate through the static filter pack 75 helps to reduce or avoid breaking up the floe. Higher flow rates can potentially cause certain types of floe to break down or disintegrate into smaller floe or individual particles. In at least some embodiments, the wastewater treatment plant 1 is able to capture very fine particles that are suspended in the wastewater. The treated water from the mechanical filtration device 15 can be discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water can be sent downstream for further treatment.

[0154] Reference will now be made to Figure 6Another embodiment of wastewater treatment plant 1 is described. In this embodiment, like reference numerals are used for like features. The description herein focuses on the differences between this embodiment of wastewater treatment plant 1 and the preceding embodiments described herein.

[0155] Wastewater treatment plant 1 in this embodiment includes an electrocoagulation unit 91. Electrocoagulation unit 91 uses an electrochemical process to remove suspended, emulsified, or dissolved contaminants from wastewater. Electrocoagulation unit 91 supplies an electric current to the wastewater to cause substances suspended in the wastewater to coagulate. Electrocoagulation unit 91 performs an electrochemical process that can use an electric charge flow to remove suspended, emulsified, or dissolved contaminants from the wastewater. Electrocoagulation unit 91 generates an electric charge flow that enters the wastewater directly to release metal ions from a sacrificial anode, which will cause the contaminants to coagulate for capture within mechanical filtration device 15. Electrocoagulation unit 91 can include one or more sacrificial electrodes (not shown) to support the electrochemical process. Electrocoagulation unit 91 is operable to cause substances suspended in the wastewater to coagulate. Particles suspended in the wastewater can coagulate or aggregate to form flocs (also known as floe). The flocs formed comprise or consist of loosely aggregated particles or soft flakes. Electrocoagulation unit 91 is located downstream of biological reactor 13. Electrocoagulation unit 91 is located upstream of mechanical filtration device 15. As shown, electrocoagulation unit 91 is disposed between biological reactor 13 and mechanical filtration device 15. Electrocoagulation unit 91 includes an electrocoagulation unit inlet 93 and an electrocoagulation unit outlet 95. Electrocoagulation unit inlet 93 is connected to at least one biological reactor outlet 43 of biological reactor 13. Wastewater filtered by biological reactor 13 is supplied to electrocoagulation unit 91. Electrocoagulation unit outlet 95 is connected to at least one mechanical filtration inlet 61. Wastewater treated by electrocoagulation unit 91 is supplied to mechanical filtration device 15. In use, electrocoagulation unit 91 is operable to cause solids waste removed from biological filtration elements in biological reactor 13 to coagulate. Coagulated material from electrocoagulation unit 91 is suspended in wastewater that is introduced to mechanical filtration device 15 disposed downstream thereof. Mechanical filtration device 15 of the type described herein is effective to perform mechanical filtration on wastewater from electrocoagulation unit 91. Figure 3

[0156] ​In use, the electrocoagulation unit 91 is operable to remove phosphate from the wastewater. The electrocoagulation unit 91 can cause phosphate to be released from solution (i.e. to settle) as a solid particle in the wastewater. The electrocoagulation unit 91 can cause other compounds to be released from solution (i.e. to settle) as a solid particle in the wastewater. For example, the solid particles can be removed using ultrafiltration or reverse osmosis. However, it has been determined that the mechanical filtration apparatus 15 described herein is also effective to filter the solid particles resulting from operation of the electrocoagulation unit 91. The mechanical filtration apparatus 15 is disposed downstream of the electrocoagulation unit 91 to remove at least some of the solid particles by mechanical filtration. The combination of the electrocoagulation unit 91 and the mechanical filtration apparatus 15 is considered to be patentably novel. This combination has particular application in wastewater treatment processes. However, other applications are also contemplated.

[0157] Figure 7 Operation of the wastewater treatment plant 1 to treat wastewater is illustrated in the second flowchart 200 shown in Figure 2. Wastewater to be treated is received by the wastewater treatment plant 1 as influent wastewater (block 205). Optionally, the wastewater is introduced into the settling tank 11 to promote settling of solids (block 210). Wastewater is discharged from the settling tank 11 to the biological reactor 13 (block 215). The biological reactor 13 biologically filters the wastewater, and the biologically filtered water is discharged from the biological reactor (block 220). Movement of the biological filtration elements causes the production of solid particles that can comprise or consist of floc, which are introduced into suspension in the wastewater discharged from the biological reactor 13. The wastewater is supplied from the biological reactor 13 to the electrocoagulation unit 91 (block 225). The electrocoagulation unit 91 is operable to coagulate the suspended solid particles (block 230). Alternatively, or additionally, the electrocoagulation unit 91 can cause phosphate dissolved in the wastewater to be released from solution and form particles. The phosphate particles can then coagulate, and the resulting coagulated particles can be suspended in the wastewater. Treated wastewater is discharged from the electrocoagulation unit 91 (block 235). The wastewater is supplied from the electrocoagulation unit 91 to the mechanical filtration apparatus 15 (block 240). The mechanical filtration apparatus 15 mechanically filters the wastewater to remove at least some of the suspended solid particles (block 245). Treated wastewater (effluent) is discharged from the mechanical filtration apparatus 15 (block 250). The mechanical filtration apparatus 15 is periodically cleaned (block 255). The cleaning comprises breaking the static filter packs 75, for example by introducing a pressurised fluid such as air (block 260). Accumulated solid waste is removed from the static filter packs and discharged from the mechanical filtration apparatus 15 (block 265). At least some of the solid waste from the mechanical filtration apparatus 15 is returned through the waste return line 83 and again through the biological reactor 13 (block 270). The process continues (block 275).

[0158] The wastewater treatment plant 1 has been described with reference to the electrocoagulation unit 91. Alternatively, or additionally, the wastewater treatment plant 1 can comprise at least one chemical dosing system 97 for introducing a (chemical) coagulant into the wastewater. The chemical dosing system 97 can be provided between the biological reactor 13 and the mechanical filtration device 15. The chemical dosing system 97 is configured to introduce a dose of coagulant into the wastewater. The coagulant can be introduced into the wastewater continuously or intermittently. The coagulant is positively charged and neutralizes solid particles suspended in the wastewater stream. In use, the coagulant promotes the coagulation or agglomeration of particles suspended in the wastewater. The coagulant can also cause dissolved compounds, such as phosphates, to release from solution to form particles. The agglomerated particles can form flocs (also referred to as floe), comprising or consisting of loosely agglomerated particles or soft flakes. At least some of the flocs are suspended in the wastewater. In the present embodiment, the coagulant is a chemical substance, such as ferric chloride or polyaluminium sulphate PAC. The coagulant can cause phosphates dissolved in the wastewater to release from solution and form particles. The particles release from solution and are agglomerated. The chemical dosing system 97 can replace the electrocoagulation unit 91. In this arrangement, the chemical dosing system 97 is located downstream of the biological reactor 13 and upstream of the mechanical filtration device 15. The chemical dosing system 97 is provided between the biological reactor 13 and the mechanical filtration device 15. The chemical dosing system 97 is configured to supply coagulant to the wastewater discharged from the biological reactor 13. The formation of chemical flocs (residence time) is a function of the volume of wastewater dosed, but a residence time of 10 to 40 minutes is suitable. The water is agitated to disperse the coagulant. The mixed water is allowed to settle, and at least some of the particles form together or agglomerate, whereby they exit the suspension (flocculate) for collection.

[0159] The coagulant can comprise or consist of an organic or inorganic chemical substance or a polymer matrix. Suitable coagulants include ferric sulphate, ferric chloride, ferrous sulphate, aluminium sulphate and aluminium chloride or polyaluminium chloride (PAM), active silica, bentonite, and metal hydroxides with a polymer structure, natural flocculants (e.g. starch derivatives, Moringa oleifera polysaccharides, and alginate or seaweed), and synthetic flocculants (e.g. polyacrylamide, polyethylene-imine, polyamines, Poly DADMACs, and polytannate, polyamide-amine, polyamine, and polyethylene oxide). The chemical dosing system 97 can be configured to introduce one or more of these coagulants into the wastewater.

[0160] Wastewater from bioreactor 13 is supplied to chemical treatment system 97. A coagulant is introduced into the wastewater, causing suspended solid particles to agglomerate. At least in certain embodiments, the coagulant can cause phosphates dissolved in the wastewater to be released from solution and form particles. The phosphate particles can aggregate to form flocs suspended in the wastewater. The treated wastewater is discharged to mechanical filtration unit 15. Mechanical filtration unit 15 mechanically filters the wastewater to remove at least some of the suspended solid particles and / or flocs. The treated wastewater (effluent) is discharged from mechanical filtration unit 15.

[0161] In use, the static filter bag 75 formed by the mechanical filter element 71 effectively filters flocs suspended in the wastewater. The mechanical filter element 71 has an open-pore structure that provides a high retention capacity. At least in certain embodiments, the flow rate per unit cross-sectional area of ​​the static filter bag 75 may be less than 20m3 / m2 / h (excluding 20m3 / m2 / h), for example, within the range of 0.1m3 / m2 / h to 19.9m3 / m2 / h; 5m3 / m2 / h to 19.5m3 / m2 / h; or 11m3 / m2 / h to 19m3 / m2 / h. It has been recognized that these flow rates per unit cross-sectional area are particularly effective for removing flocs from wastewater. Flocs can settle within or outside the filter unit 73 of the mechanical filter element 71. The relatively low flow rate through the static filter bag 75 helps to reduce or avoid damaging the flocs. A higher flow rate can potentially cause certain types of flocs to decompose or disintegrate into smaller flocs or individual particles.

[0162] The coagulation and flocculation process produces particles that then need to be captured. The mechanical filter device 15 described herein can effectively perform this operation. At least in certain embodiments, this can be performed without the need to utilize a settling tank and / or without the need for large amounts of water to backwash or clean the filter screen. The open-pore structure of the mechanical filter element 71 is suitable for keeping softer flocs within the filter unit. The mechanical filter element 71 has a high retention capacity for accumulating waste without forming a barrier (floc accumulation) that water would then be unable to penetrate.

[0163] Now refer to Figure 8 describe Figure 6 The same reference numerals are used for the same components. This description focuses on the wastewater treatment plant 1 according to this embodiment and the wastewater treatment plant 1 according to the reference embodiment. Figure 8 Differences between the described embodiments.

[0164] The wastewater treatment plant 1 comprises a primary screen 9, a primary settling tank 11, a biological reactor 13, and a mechanical filtration device 15. The wastewater treatment plant 1 can optionally comprise a tertiary settling tank 20. The tertiary settling tank 20 can be provided between the biological reactor 13 and the mechanical filtration device 15. In the present embodiment, the biological reactor 13 comprises a moving bed biological reactor (MBBR). Other types of biological reactors 13 can be considered. It will be appreciated that one or more of the primary settling tank 11, the biological reactor 13, and the mechanical filtration device 15 can comprise a civil installation, for example in the form of a concrete tank, a steel tank, or a glass fibre reinforced polymer (GFRP) tank.

[0165] The wastewater treatment plant 1 in the present embodiment comprises a first chemical system 97-1 and a second chemical system 97-2. The first chemical system 97-1 is provided upstream of the biological reactor 13; the second chemical system 97-2 is provided downstream of the biological reactor 13. In the present embodiment, the first chemical system 97-1 is provided between the primary settling tank 11 and the biological reactor 13; and the second chemical system 97-2 is provided between the biological reactor 13 and the mechanical filtration device 15. The first and second chemical systems 97-1, 97-2 are configured to introduce a coagulant into the wastewater. The coagulant can cause one or more dissolved compounds, such as phosphates, to be released from solution and form particles. Alternatively, or additionally, microbial aggregates on the biological filtration elements can be dislodged, thereby introducing more particles into the wastewater. The coagulant promotes the coagulation or agglomeration of particles suspended in the wastewater. The coagulant can promote the coagulation of particles in the wastewater, for example to form flocs. The wastewater treatment plant 1 can be modified to replace at least one of the first and second chemical systems 97-1, 97-2 with one or more electrocoagulation units 91 of the type described herein.

[0166] The mechanical filtration apparatus 15 is configured to perform mechanical filtration of the wastewater to remove at least some of the solid particles suspended in the wastewater discharged from the biological reactor 13. The mechanical filtration apparatus 15 comprises a mechanical filtration tank 60, at least one mechanical filtration inlet 61, at least one mechanical filtration outlet 63, at least one mechanical filtration air inlet 65, and at least one mechanical filtration waste outlet 67. The at least one mechanical filtration inlet 61 is in fluid communication with the at least one biological reactor outlet 43. In use, wastewater from the biological reactor 13 is introduced into the mechanical filtration apparatus 15 through the at least one mechanical filtration inlet 61. The at least one mechanical filtration inlet 61 is preferably provided in a lower region of the mechanical filtration apparatus 15; and the at least one mechanical filtration outlet 63 is preferably provided in an upper region of the mechanical filtration apparatus 15. The mechanical filtration apparatus 15 filters the wastewater supplied from the biological reactor 13. The mechanical filtration chamber 70 comprises a mechanical filtration medium 69 for performing mechanical filtration of the wastewater. The mechanical filtration medium 69 comprises a plurality of mechanical filtration elements 71 of the type described herein. The mechanical filtration elements 71 form a static filtration pack 75 which is adapted to filter particles and matter suspended in the water as the water flows through the mechanical filtration apparatus 15. The mechanical filtration elements 71 have an open-structured configuration to facilitate settling of the suspended particles in the static filtration pack 75. The mechanical filtration elements 71 each have one or more filtration units 73. The wastewater is filtered by the mechanical filtration medium 69 to remove at least some of the solid particles suspended in the wastewater supplied from the biological reactor 13. The treated wastewater (effluent) is discharged from the mechanical filtration apparatus 15 through the at least one mechanical filtration outlet 63.

[0167] The mechanical filtration apparatus 15 is periodically cleaned to discharge the solids accumulated in the mechanical filtration chamber 70. Cleaning of the mechanical filtration apparatus 15 is performed using the methods described herein. A portion of the wastewater discharged from the mechanical filtration chamber 70 can be recirculated for further treatment within the wastewater treatment plant 1. In the present embodiment, a waste recirculation line 83 is provided for recirculating the wastewater discharged from the mechanical filtration apparatus 15. A waste control valve 85 can optionally be provided to control the supply of waste to the waste recirculation line 83. In the present embodiment, a portion of the waste from the mechanical filtration chamber 70 is recirculated to the biological reactor 13. The waste recirculated from the mechanical filtration apparatus 15 is typically in the form of sludge (comprising or consisting of settled solid matter). The waste can be introduced into the biological reactor 13 through the biological reactor inlet 41 or a separate inlet. A portion of the waste discharged from the mechanical filtration chamber 70 can be sent to waste or further treatment downstream of the wastewater treatment plant 1.

[0168] In use, the mechanical filter element 71 forms a static filter pack 75 which is operable to filter solids from the wastewater. The mechanical filter element 71 can have a positive buoyancy, a negative buoyancy or a neutral buoyancy. The mechanical filter element 71 has an open structure which provides a high retention capacity. The flow rate per unit cross-sectional area of the static filter pack 75 can be less than 20 m3 / m2 / h (not including 20 m3 / m2 / h), for example in the range of 0.1 m3 / m2 / h to 19.9 m3 / m2 / h; 5 m3 / m2 / h to 19.5 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h. It has been recognised that these flow rates per unit cross-sectional area are particularly effective at removing floe (also known as flocculation clumps) from the wastewater. Floe comprises or consists of loosely aggregated particles or soft flakes. At least in certain embodiments, floe can settle within or outside the filter cells 73 of the mechanical filter element 71. The relatively low flow rate through the static filter pack 75 helps to reduce or avoid breaking up the floe. Higher flow rates can potentially cause certain types of floe to break down or disintegrate into smaller floe or individual particles. The treated water from the mechanical filtration plant 15 can be discharged from the wastewater treatment plant 1 or sent to a receiving watercourse. Alternatively, the treated water can be sent downstream for further treatment.

[0169] Reference will now be made to Figure 9 described embodiments of the wastewater treatment plant 1. Figure 8 The present description focuses on the differences between the wastewater treatment plant 1 according to embodiments of the present application and the embodiments described with reference to Figure 9 described embodiments.

[0170] The wastewater treatment plant 1 includes a primary screen 9, a primary settling tank 11, a biological reactor 13 and a mechanical filtration plant 15. The wastewater treatment plant 1 can optionally include a tertiary settling tank 20. The tertiary settling tank 20 can be provided between the biological reactor 13 and the mechanical filtration plant 15. In this embodiment, the biological reactor 13 includes a moving bed biological reactor (MBBR). Other types of biological reactor 13 can be considered. For example, the biological reactor 13 can include a submerged aerated filter (SAF) of the type described herein.

[0171] The wastewater treatment plant 1 includes a first chemical system 97-1, a second chemical system 97-2, and a third chemical system 97. The first chemical system 97-1 is disposed upstream of the biological reactor 13. In the present embodiment, the first chemical system 97-1 is disposed between the primary settling tank 11 and the biological reactor 13. The second and third chemical systems 97-2, 97-3 are disposed downstream of the biological reactor 13. The second chemical system 97-2 is disposed between the biological reactor 13 and the tertiary settling tank 20. The third chemical system 97-3 is disposed between the tertiary settling tank 20 and the mechanical filtration device 15. Each of the first, second, and third chemical systems 97-1, 97-2, 97-3 is configured to introduce a coagulant into the wastewater. The coagulant can cause one or more dissolved compounds, such as phosphates, to be released from solution and form particles. The coagulant promotes coagulation or agglomeration of particles suspended in the wastewater. The coagulant can promote coagulation of particles in the wastewater, for example, to form floc. The wastewater treatment plant 1 can be modified to replace at least one of the first, second, and third chemical systems 97-1, 97-2, 97-3 with one or more electrocoagulation units 91 of the type described herein.

[0172] Operation of the wastewater treatment plant 1 according to the present embodiment is consistent with the other embodiments described herein. The mechanical filtration device 15 is operable to filter particulate matter and floc from the wastewater. The flow rate per unit cross-sectional area of the static filter pack 75 can be less than 20 m3 / m2 / h (not including 20 m3 / m2 / h), for example, in a range of 0.1 m3 / m2 / h to 19.9 m3 / m2 / h; 5 m3 / m2 / h to 19.5 m3 / m2 / h; or 11 m3 / m2 / h to 19 m3 / m2 / h. The mechanical filtration medium 69 can have a positive buoyancy, neutral buoyancy, or negative buoyancy. In the present embodiment, the mechanical filtration medium 69 has a positive buoyancy.

[0173] The wastewater treatment plant 1 described herein can be a sewage treatment plant 1. The wastewater to be treated is in the form of sewage. The wastewater treatment plant 1 described herein can be a municipal sewage treatment plant 1 for treating municipal sewage. For example, the sewage treatment plant 1 can treat 1.2 million liters of wastewater per day. The wastewater treatment plant 1 should be able to treat the wastewater to meet the discharge permit in order to remain in compliance with legal regulations. The discharge permit typically contains contaminant limits, including biochemical oxygen demand (BOD), total suspended solids (TSS), phosphates (P), nitrates (N), and ammonia in the form of ammonia (NH3 / N). The discharge permit is set by the water utility when the water is received for treatment and by a regulatory agency when discharged into the environment. It is particularly important to remove macronutrients such as phosphates and nitrates because these nutrients can have a negative impact on the receiving waterway.

[0174] The flow rate per unit cross-sectional area of the mechanical filtration medium 69 affects the filtration of the wastewater as described herein. The retention capacity of the mechanical filtration device 15 depends on the volume of the mechanical filtration medium 69 in the mechanical filtration tank 60. To facilitate cleaning of the mechanical filtration medium 69, the filtration medium 69 preferably occupies between about 40% and 60% of the volume of the mechanical filtration chamber 70. In a preferred embodiment, the filtration medium 69 occupies about 50% of the volume of the mechanical filtration chamber 70.

[0175] The mechanical filtration device 15 can comprise mechanical filtration tanks 60 of different sizes. The mechanical filtration tank 60 can comprise or consist of a cylindrical portion having a circular cross-section. The mechanical filtration tank 60 can have a different cross-section, for example a polygonal, rectangular or square cross-section. The mechanical filtration tank 60 can be oriented so that the central longitudinal axis extends vertically or horizontally. The mechanical filtration chamber 70 formed in the mechanical filtration tank 60 has a height (h) and a width (w). In the case where the mechanical filtration tank 60 comprises or consists of a cylindrical portion, the width (w) corresponds to the diameter of the cylindrical portion and the height (h) corresponds to the height of the cylindrical portion (i.e. excluding any tapered or curved end portions). The ratio of the height (h) to the width (w) of the mechanical filtration tank 60 is preferably between 1.5 (inclusive) and 2 (inclusive). The ratio of the height (h) to the width (w) of the mechanical filtration tank 60 is preferably between 1.75 (inclusive) and 2 (inclusive). It has been determined that the mechanical filtration tank 60 having this ratio of height (h) to width (w) is particularly effective if the mechanical filtration medium 69 occupies between 40% and 60% of the volume of the mechanical filtration chamber 70. A mechanical filtration tank 60 having a height (h) equal to about twice its width (w) and containing filtration medium 69 occupying 50% of the volume is particularly preferred. The depth of the filtration pack formed by the mechanical filtration medium 69 in the mechanical filtration chamber 70 is preferably approximately equal to the width (w) of the mechanical filtration tank 60.

[0176] Figure 10A A first mechanical filtration tank 60A is shown by way of example. The first mechanical filtration tank 60 comprises a cylindrical portion. The first mechanical filtration tank 60 comprises a mechanical filtration inlet 61, a mechanical filtration outlet 63 and a mechanical filtration waste outlet 67. The diameter of the cylindrical portion of the first mechanical filtration tank 60A is 1.2m.

[0177] Figure 10B A second mechanical filtration tank 60B is shown by way of example. The second mechanical filtration tank 60 comprises a cylindrical portion. The second mechanical filtration tank 60B comprises a mechanical filtration inlet 61, a mechanical filtration outlet 63 and a mechanical filtration waste outlet 67. The diameter of the cylindrical portion of the first mechanical filtration tank 60B is 0.9m.

[0178] Figure 10CA third mechanical filter tank 60C is shown by way of example. The third mechanical filter tank 60 comprises a cylindrical portion. The third mechanical filter tank 60C comprises a mechanical filter inlet 61, a mechanical filter outlet 63 and a mechanical filter waste outlet 67. The diameter of the cylindrical portion of the third mechanical filter tank 60C is 0.75m.

[0179] Figure 10D A fourth mechanical filter tank 60D is shown by way of example. The fourth mechanical filter tank 60 comprises a cylindrical portion. The fourth mechanical filter tank 60D comprises a mechanical filter inlet 61, a mechanical filter outlet 63 and a mechanical filter waste outlet 67. The diameter of the cylindrical portion of the fourth mechanical filter tank 60D is 0.6m.

[0180] Figure 10E A fifth mechanical filter tank 60E is shown by way of example. The fourth mechanical filter tank 60 comprises a cylindrical portion. The fourth mechanical filter tank 60E comprises a mechanical filter inlet 61, a mechanical filter outlet 63 and a mechanical filter waste outlet 67. The diameter of the cylindrical portion of the fourth mechanical filter tank 60E is 0.5m.

[0181] The size of the mechanical filter apparatus 15 depends on the flow rate of wastewater to be treated. The wastewater treatment plant 1 can be a sewage treatment plant configured to treat sewage. Sewage is typically defined in terms of population equivalent (PE) which represents the volume of wastewater per person (typically defined as 150 to 180 litres per day). The treated water from the wastewater treatment plant 1 must comply with certain standards (defined in BS EN 12566-3 in the UK). The standards can define threshold values for one or more of: biochemical oxygen demand (BOD), suspended solids (SS) and ammonia (NH4-N) content. The BOD threshold value can be defined as 20mg / l (BOD of 20mg / l). The suspended solids threshold value can be defined as less than 30mg / l (SS < 30mg / l). The ammonia threshold value can be defined as less than 20mg / l. There can be requirements in respect of other pollutants such as nitrates and phosphates.

[0182] Table A below summarises the operating parameters for a small (sewage) works. The wastewater treatment plant 1 comprises at least one mechanical filter apparatus 15 of the type described herein for mechanical filtration of wastewater discharged from the biological reactor 13. The table summarises the number and size (diameter ) of the mechanical filter apparatus 15 in the wastewater treatment plant 1. In the present example, the wastewater treatment plant 1 comprises a single mechanical filter apparatus 15 having a diameter of 0.6m.

[0183]

[0184] Table A

[0185] Table B below outlines operational parameters for a series of small-scale (sewage) works. The wastewater treatment plant 1 comprises at least one mechanical filtration apparatus 15 of the type described herein for mechanical filtration of wastewater discharged from the biological reactor 13. The table outlines the number and size (diameter ) of the mechanical filtration apparatus 15 in the wastewater treatment plant 1. In this example, the wastewater treatment plant 1 contains a single mechanical filtration apparatus 15 having a diameter of 0.6m.

[0186]

[0187]

[0188] Table B

[0189] Table C below outlines operational parameters for a large-scale (sewage) works. The wastewater treatment plant 1 comprises at least one mechanical filtration apparatus 15 of the type described herein for mechanical filtration of wastewater discharged from the biological reactor 13. The table outlines the number and size (diameter ) of the mechanical filtration apparatus 15 in the wastewater treatment plant 1. In this example, the wastewater treatment plant 1 contains a single mechanical filtration apparatus 15 having a diameter of 0.6m.

[0190]

[0191] Table C

[0192] It will be appreciated that various changes and modifications can be made to the application without departing from the scope thereof.

[0193] Other aspects of the application are set out in the following numbered paragraphs:

[0194] 1. A wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0195] receiving wastewater to be treated;

[0196] supplying the wastewater to a biological reactor, the biological reactor comprising a biological filtration medium for biological filtration of wastewater, the biological filtration medium comprising a plurality of biological filtration elements for supporting a community of microorganisms on a surface of the biological filtration medium in the wastewater, wherein during filtration the biological filtration elements circulate within the biological reactor, the circulation of the biological filtration elements resulting in solid waste being removed from the biological filtration elements and suspended in the wastewater;

[0197] wastewater discharged from the bioreactor is supplied to a mechanical filtration apparatus disposed downstream of the bioreactor, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering solid waste removed from the biological filtration elements in the bioreactor and suspended in the wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0198] discharging treated wastewater.

[0199] 2. The wastewater treatment method of paragraph 1, comprising:

[0200] supplying the wastewater to a settling tank upstream of the bioreactor to settle solids; and supplying the wastewater from the settling tank to the bioreactor.

[0201] 3. The wastewater treatment method of paragraph 1 or paragraph 2, comprising introducing pressurized air into the bioreactor to circulate the biological filtration media within the bioreactor.

[0202] 4. The wastewater treatment method of any of the preceding paragraphs, comprising periodically cleaning the mechanical filtration apparatus to remove solid waste accumulated in the static filtration pack, wherein cleaning the mechanical filtration apparatus comprises disrupting the static filtration pack to remove solid waste accumulated in the mechanical filtration elements.

[0203] 5. The wastewater treatment method of paragraph 4, wherein the static filtration pack is disrupted after shutting down at least one of a mechanical filtration apparatus inlet for receiving wastewater from the bioreactor and a mechanical filtration apparatus outlet for discharging treated wastewater from the mechanical filtration apparatus.

[0204] 6. The wastewater treatment method of paragraph 4 or paragraph 5, wherein air is introduced into the mechanical filtration apparatus at a pressure greater than atmospheric pressure to disrupt the static filtration pack.

[0205] 7. The wastewater treatment method of any of paragraphs 4, 5, or 6, comprising opening a mechanical filtration apparatus waste outlet to discharge at least some of the wastewater in the mechanical filtration apparatus and solid waste removed from the mechanical filtration elements.

[0206] 8. The wastewater treatment method of any of paragraphs 4 to 7, wherein at least some of the solid waste removed from the mechanical filtration elements is reintroduced upstream of the bioreactor for further biological filtration.

[0207] 9. The wastewater treatment method of paragraph 8, wherein the solid waste removed from the mechanical filtration elements is introduced directly into the bioreactor.

[0208] 10. A wastewater treatment method as claimed in paragraph 8, when directly or indirectly referring to paragraph 2, wherein the solid waste removed from the mechanical filtration elements is introduced into the settling tank.

[0209] 11. A wastewater treatment method as claimed in any one of the preceding paragraphs, comprising using an electrocoagulation unit to coagulate material suspended in the wastewater.

[0210] 12. A wastewater treatment method as claimed in paragraph 11, wherein the electrocoagulation unit is located upstream of the mechanical filtration apparatus, coagulating material suspended in wastewater introduced into the mechanical filtration apparatus.

[0211] 13. A wastewater treatment method as claimed in paragraph 11 or paragraph 12, wherein the electrocoagulation unit is located downstream of the biological reactor, and coagulates solid waste removed from the biological filtration elements in the biological reactor.

[0212] 14. A wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0213] receiving wastewater to be treated;

[0214] supplying the wastewater to a biological reactor comprising a biological filtration medium for biologically filtering the wastewater, the biological filtration medium comprising a plurality of biological filtration elements for supporting a population of microorganisms on a surface of the biological filtration medium in the wastewater, wherein during filtration the biological filtration elements circulate within the biological reactor, the circulation of the biological filtration elements resulting in solid waste being removed from the biological filtration elements and suspended in the wastewater;

[0215] supplying wastewater discharged from the biological reactor to an electrocoagulation unit to coagulate solid waste removed from the biological filtration elements in the biological reactor; and

[0216] discharging treated wastewater.

[0217] 15. A wastewater treatment method for treating wastewater, the wastewater treatment method comprising:

[0218] receiving wastewater to be treated;

[0219] supplying the wastewater to an electrocoagulation unit to coagulate solid material suspended in the wastewater;

[0220] supplying the wastewater from the electrocoagulation unit to a mechanical filtration apparatus, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering coalesced solid matter from the electrocoagulation unit, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0221] discharging treated wastewater.

[0222] 16. A wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0223] an inlet for receiving wastewater to be treated;

[0224] a bioreactor comprising a biological filtration medium for biologically filtering the wastewater, the biological filtration medium being suitable for supporting a population of microorganisms, the bioreactor comprising means for circulating the biological filtration medium within the bioreactor during filtration; and

[0225] a mechanical filtration apparatus disposed downstream of the bioreactor, wherein the mechanical filtration apparatus comprises a static filtration pack for filtering solid waste removed from the biological filtration elements in the bioreactor and suspended in the wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and

[0226] an outlet for discharging treated wastewater.

[0227] 17. The wastewater treatment plant of paragraph 16, comprising:

[0228] a settling tank for facilitating settling of solids suspended in the wastewater, the settling tank being located upstream of the bioreactor.

[0229] 18. The wastewater treatment plant of paragraph 16 or paragraph 17, comprising a pressurised air supply for introducing pressurised air into the bioreactor to circulate the biological filtration medium within the bioreactor.

[0230] 19. The wastewater treatment plant of any one of paragraphs 16, 17 or 18, comprising means for disrupting the static filtration pack in the mechanical filtration apparatus to remove solid waste accumulated in the mechanical filtration elements.

[0231] 20. The wastewater treatment plant of paragraph 19, comprising one or more valves for closing at least one of the mechanical filtration apparatus inlet and the mechanical filtration apparatus outlet when the static filtration pack is disrupted.

[0232] 21. The wastewater treatment plant of paragraph 19 or paragraph 20, comprising a supply of pressurised air for introducing air into the mechanical filtration apparatus to disrupt the static filter packs.

[0233] 22. The wastewater treatment plant of any one of paragraphs 19, 20 or 21, comprising a mechanical filtration apparatus waste outlet operable to discharge at least some of the wastewater from the mechanical filtration apparatus.

[0234] 23. The wastewater treatment plant of paragraph 22, comprising a backflow line configured to backflow at least some of the wastewater from the mechanical filtration apparatus for reintroduction into the wastewater treatment plant upstream of the biological reactor.

[0235] 24. The wastewater treatment plant of paragraph 23, wherein the backflow line is connected to the biological reactor to backflow the wastewater from the mechanical filtration apparatus into the biological reactor.

[0236] 25. The wastewater treatment plant of paragraph 23, when directly or indirectly referring to paragraph 17, wherein the backflow line is connected to the settling tank to backflow the wastewater from the mechanical filtration apparatus into the settling tank.

[0237] 26. The wastewater treatment plant of any one of paragraphs 16 to 25, comprising an electrocoagulation unit for coagulating material suspended in the wastewater.

[0238] 27. The wastewater treatment plant of paragraph 26, wherein the electrocoagulation unit is located upstream of the mechanical filtration apparatus; in use, coagulated material is suspended in the wastewater introduced into the mechanical filtration apparatus.

[0239] 28. The wastewater treatment plant of paragraph 26 or paragraph 27, wherein the electrocoagulation unit is located downstream of the biological reactor, and in use, the electrocoagulation unit is operable to coagulate solid waste suspended in the wastewater discharged from the biological reactor.

[0240] 29. A wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0241] an inlet for receiving wastewater to be treated;

[0242] a biological reactor comprising a biological filtration medium for biologically filtering the wastewater, the biological filtration medium being suitable for supporting a population of microorganisms, the biological reactor comprising means for circulating the biological filtration medium within the biological reactor during filtration; and

[0243] An electrocoagulation unit disposed downstream of the bioreactor, the electrocoagulation unit configured to coagulate matter suspended in wastewater discharged from the bioreactor.

[0244] 30. A wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising:

[0245] an inlet for receiving wastewater to be treated;

[0246] an electrocoagulation unit for coagulating solid matter suspended in the wastewater;

[0247] a mechanical filtration device disposed downstream of the electrocoagulation unit, wherein the mechanical filtration device comprises a static filtration pack for filtering coagulated solid matter discharged from the electrocoagulation unit and suspended in wastewater, the static filtration pack comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration cells; and

[0248] an outlet for discharging treated wastewater.

[0249] a first flowchart symbol

[0250] a second flowchart symbol

Claims

1. A wastewater treatment method for treating wastewater, the wastewater treatment method comprising: Receive wastewater for treatment; supplying the wastewater to a bioreactor to perform biological filtration on the wastewater; supplying the wastewater discharged from the bioreactor to a mechanical filtration device disposed downstream of the bioreactor, wherein the mechanical filtration device comprises a static filtration bag for filtering solid waste suspended in the wastewater, the static filtration bag comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and Discharge treated wastewater.

2. The wastewater treatment method according to claim 1, wherein the bioreactor comprises a biological filtration medium for biologically filtering the wastewater, the biological filtration medium comprising a plurality of biological filtration elements, the biological filtration elements being configured to support a community of microorganisms on a surface of the biological filtration medium to biologically filter the wastewater; The static filtration package in the mechanical filtration device filters solid waste removed from the biological filtration element in the bioreactor and suspended in the wastewater discharged from the bioreactor.

3. The wastewater treatment method according to claim 2, wherein the biological filter element circulates within the bioreactor during filtration, and the circulation of the biological filter element causes solid waste to be removed from the biological filter element and suspended in the wastewater discharged from the bioreactor.

4. The wastewater treatment method according to any one of claims 1, 2 or 3, comprising: The wastewater is supplied to a first settling tank to settle solids, the first settling tank being located upstream of the bioreactor; and the wastewater is supplied from the first settling tank to the bioreactor.

5. The wastewater treatment method of claim 4, wherein at least some of the solid waste accumulated in the mechanical filtration device is reintroduced into the first settling tank.

6. The wastewater treatment method according to any one of the preceding claims, comprising: The wastewater is supplied from the bioreactor to a second settling tank to settle solids, the second settling tank being located downstream of the bioreactor; and the wastewater is supplied from the settling tank to the mechanical filtration device.

7. A method of treating wastewater according to any one of the preceding claims, comprising introducing pressurised air into the bioreactor to circulate the biological filter medium within the bioreactor.

8. The wastewater treatment method according to any one of the preceding claims, comprising periodically cleaning the mechanical filtration device to remove solid waste accumulated in the static filter bag, wherein cleaning the mechanical filtration device comprises destroying the static filter bag to dislodge the solid waste accumulated in the mechanical filter element.

9. The wastewater treatment method according to claim 8, wherein the static filter bag is destroyed after closing at least one of the mechanical filter device inlet for receiving wastewater from the bioreactor and the mechanical filter device outlet for discharging treated wastewater from the mechanical filter device.

10. The wastewater treatment method according to claim 8 or 9, wherein a pressurized fluid is introduced into the mechanical filtration device to destroy the static filter packs.

11. A method of treating wastewater according to any one of claims 8, 9 or 10, comprising opening a waste outlet of a mechanical filter device to discharge at least some of the wastewater in the mechanical filter device and solid waste removed from the mechanical filter element.

12. A wastewater treatment method according to any preceding claim, comprising reintroducing at least some of the solid waste accumulated in the mechanical filtration device into the bioreactor or upstream of the bioreactor for further biological filtration.

13. A method of treating wastewater according to any preceding claim, comprising using an electro-flocculation unit to agglomerate materials suspended in the wastewater.

14. The wastewater treatment method according to claim 13, wherein the electric flocculation unit is located upstream of the mechanical filtering device, and the agglomerated substances are suspended in the wastewater introduced into the mechanical filtering device.

15. The wastewater treatment method according to claim 13 or 14, wherein the electro-flocculation unit is located downstream of the bioreactor and agglomerates the solid waste removed from the biofiltration element in the bioreactor.

16. A wastewater treatment method according to any one of the preceding claims, comprising introducing a coagulant into the wastewater upstream of the mechanical filtration device.

17. The wastewater treatment method according to claim 16, wherein the coagulant releases phosphate dissolved in the wastewater from the solution and forms particles, and the static filtration package of the mechanical filtration device filters the particles formed by the coagulant.

18. The wastewater treatment method according to claim 17, wherein the coagulant causes particles comprising or consisting of phosphate to aggregate and form flocs, and the static filter bag of the mechanical filtration device filters the flocs from the wastewater.

19. The wastewater treatment method according to any one of the preceding claims, comprising: a flow rate per unit cross-sectional area of ​​the static filter pack formed in the mechanical filtration device is in the range of 0.1 m3 / m2 / h to 19 m3 / m2 / h.

20. A wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising: an inlet for receiving wastewater to be treated; a bioreactor comprising a biofiltration medium for biofiltering the wastewater; and a mechanical filtration device disposed downstream of the bioreactor, wherein the mechanical filtration device comprises a static filtration bag for filtering solid waste suspended in the wastewater, the static filtration bag comprising a plurality of mechanical filtration elements, each mechanical filtration element having one or more filtration units; and Outlet for discharging treated wastewater.

21. The wastewater treatment plant according to claim 20, wherein the bioreactor comprises a biological filtration medium for biologically filtering the wastewater, the biological filtration medium comprising a plurality of biological filtration elements, the biological filtration elements being configured to support a community of microorganisms on a surface of the biological filtration medium to biologically filter the wastewater; The static filtration comprises filtering solid waste removed from the biological filtration element in the bioreactor and suspended in wastewater discharged from the bioreactor.

22. A wastewater treatment plant according to claim 21, comprising means for circulating the biological filter element within the bioreactor during filtration; wherein In use, circulation of the biofilter element causes solid waste to be removed from the biofilter element and suspended in the wastewater discharged from the bioreactor.

23. The wastewater treatment plant of claim 22, wherein the means for circulating the biological filtration element comprises a pump for introducing pressurized liquid or air into the bioreactor to circulate the biological filtration medium within the bioreactor.

24. The wastewater treatment plant according to any one of claims 20 to 23, comprising: A first settling tank is used to promote the settling of solids suspended in the wastewater, and the first settling tank is located upstream of the bioreactor.

25. The wastewater treatment plant according to any one of claims 20 to 24, comprising: A second sedimentation tank is used to promote the sedimentation of solids suspended in the wastewater, and the second sedimentation tank is located between the bioreactor and the mechanical filtration device.

26. The wastewater treatment plant according to any one of claims 20 to 25, comprises a device for destroying the static filter bag in the mechanical filtration equipment to remove solid waste accumulated in the mechanical filter element, the destruction device comprising one or more of the following: a pump for introducing pressurized air into the static filter bag; a pump for introducing pressurized liquid into the static filter bag; a mechanical agitator for stirring the mechanical filter element; and one or more air inlets for drawing air into the mechanical filtration equipment.

27. A wastewater treatment plant according to any one of claims 20 to 26, comprising a mechanical filter device waste outlet for discharging accumulated solid waste from the mechanical filter device.

28. The wastewater treatment plant of claim 27, comprising a return line for returning at least some of the solid waste accumulated in the mechanical filtration device to the bioreactor or upstream of the bioreactor.

29. The wastewater treatment plant of claim 28 when directly or indirectly dependent upon claim 24, wherein the return line is connected to the first settling tank to return at least some of the solid waste accumulated in the mechanical filtration device to the first settling tank.

30. A wastewater treatment plant according to any one of claims 20 to 29, comprising at least one electroflocculation unit for agglomerating substances suspended in the wastewater.

31. A wastewater treatment plant according to claim 30, wherein the at least one electroflocculation unit is located upstream of the mechanical filtration device; and in use, agglomerated material is suspended in wastewater introduced into the mechanical filtration device.

32. A wastewater treatment plant according to claim 30 or 31, wherein the at least one electroflocculation unit is located downstream of the bioreactor and, in use, is operable to agglomerate solid waste suspended in wastewater discharged from the bioreactor.

33. The wastewater treatment plant according to any one of claims 20 to 32, comprising at least one coagulant system for introducing a coagulant into the wastewater upstream of the mechanical filtration device.

34. The wastewater treatment method according to claim 33, wherein: In use, the coagulant causes phosphates dissolved in the wastewater to be released from solution and to form particles; the static filter pack of the mechanical filtration apparatus is configured to filter particles comprising or consisting of phosphates.

35. The wastewater treatment method according to claim 34, wherein: In use, the particles comprising or consisting of phosphates are caused to agglomerate to form flocs, and the static filter packs of the mechanical filtration apparatus are configured to filter the flocs from wastewater.

36. The wastewater treatment method according to any one of claims 20 to 35, comprising at least one pump for pumping wastewater through the mechanical filtration device, wherein the at least one pump is configured to establish a flow rate per unit cross-sectional area of ​​the static filter pack formed in the mechanical filtration device in the range of 0.1 m3 / m2 / h to 19 m3 / m2 / h.

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