Wastewater treatment method and apparatus

Abstract

Embodiments of the present invention relate to a wastewater treatment process (100) and a wastewater treatment plant (1) for treating wastewater. The wastewater treatment process (100) includes receiving wastewater for treatment. The wastewater is fed to a bioreactor (13), where biological filtration of the wastewater occurs. The wastewater is discharged from the bioreactor (13) to a mechanical filter device (15) located downstream of the bioreactor (13). The mechanical filter device (15) includes a fixed-bed filter pack (75) for filtering solid waste suspended in the wastewater. The fixed-bed filter pack (75) includes a plurality of mechanical filter elements (71), each having one or more filter cells (73). The treated wastewater is discharged.

Description

[Technical Field]

[0001] The present disclosure relates to wastewater treatment methods and apparatus. Aspects of the present invention relate to wastewater treatment processes and wastewater treatment plants. The wastewater includes, for example, industrial wastewater and / or municipal wastewater. The wastewater treatment methods and apparatus of the present invention can also be used to treat wastewater in water reuse applications. [Background technology]

[0002] It is known to use bioreactors to perform biological filtration of wastewater. Bioreactors, for example, include a filter medium that supports colonies of microorganisms that convert organic matter present in the wastewater, thereby providing biological filtration. The bioreactor can be configured to support aerobic or anaerobic microorganisms for biological filtration. The filter medium can include multiple biological filter elements that circulate within the bioreactor (a so-called fluidized-bed bioreactor).

[0003] The present inventors have recognized that movement of biological filter elements within a bioreactor can result in solid particles suspended in the wastewater. The movement of the biological filter elements, for example, can cause material to be dislodged when the biological filter elements contact each other and / or the sidewalls of the bioreactor. The dislodged material can include accumulated waste and / or clumps of dead microorganisms filtered from the wastewater. The dislodged solid particles can be relatively small, measuring 5 pm or less in diameter. The inventors have determined that additional filtration can be performed to remove at least a portion of the solid particles discharged from the bioreactor. It has been recognized that when the biological filter element is in a fixed bed, e.g., a submerged foam bed, material can break off from the surface of the biological filter element. As a result, solids can settle in the wastewater, for example, in the form of suspended particles. Other forms of biological filtration can result in particles and waste being introduced into the wastewater.

[0004] SUMMARY OF THE INVENTION It is an object of the present invention to address one or more of the shortcomings associated with the prior art. Summary of the Invention [Means for solving the problem]

[0005] Aspects and embodiments of the present invention provide wastewater treatment processes and wastewater treatment plants as set out in the accompanying claims.

[0006] According to one aspect of the present invention, there is provided a wastewater treatment process for treating wastewater, the wastewater treatment process comprising the steps of receiving and treating the wastewater, supplying the wastewater to a bioreactor for biological filtration of the wastewater, supplying the wastewater discharged from the bioreactor to a mechanical filter device located downstream of the bioreactor, the mechanical filter device comprising a fixed-bed filter pack for filtering solid waste suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells, and discharging the treated wastewater.

[0007] The mechanical filter device includes a plurality of mechanical filter elements. The mechanical filter elements form a stationary filter pack that mechanically filters wastewater as it passes through the mechanical filter device. The mechanical filter device can include a filter tank that forms a filter chamber in which the mechanical filter elements are disposed. The filter cell or cells formed in each mechanical filter element have an open-cell structure. Wastewater can flow into the filter cell or cells. Mechanical filtration occurs by promoting the settling of particles within the filter cell or cells.

[0008] The bioreactor may include a biological filter medium for biologically filtering the wastewater. The biological filter medium may include a plurality of biological filter elements for supporting colonies of microorganisms on the surface of the biological filter medium for biologically filtering the wastewater. The biological filter elements may be circulated within the bioreactor, i.e., forming a fluidized-bed biological filter. Alternatively, the biological filter elements may be stationary within the bioreactor, i.e., forming a fixed-bed biological filter. Other types of bioreactors are also contemplated. For example, the bioreactor may not include a biological filter medium.

[0009] The fixed-bed filter pack of the mechanical filter device operates to filter solid waste discharged from the bioreactor. The solid waste may be removed from the surface of the biological filter element within the bioreactor. The solid waste may be removed when biological filter elements within a fluidized bed system contact each other. The solid waste may be removed when the biological filter elements form a fixed-bed biological filter. Other mechanical, hydraulic, or biological processes may remove the solid waste from the biological filter element. The solid waste may be suspended in the wastewater discharged from the bioreactor.

[0010] The biological filter element can be stationary within the bioreactor during biological filtration. Alternatively, the biological filter element can be circulated within the bioreactor during biological filtration. Circulation of the biological filter element can dislodge solid waste from the biological filter element and cause it to become suspended in the wastewater discharged from the bioreactor. The solid waste can include waste from the wastewater and / or microbial mass separated from the biological filter element.

[0011] The process can include feeding the wastewater to a first settling tank for solids settling, which can be located upstream of the bioreactor and feeding the wastewater from the first settling tank to the bioreactor.

[0012] The process may include feeding the wastewater from the bioreactor to a second settling tank for settling of solids. The second settling tank may be located downstream of the bioreactor. The wastewater from the settling tank may be fed to a mechanical filter device.

[0013] The process may include introducing pressurized air into the bioreactor to circulate the biological filter media within the bioreactor. Alternatively, or in addition, a mechanical agitator may be provided to agitate the biological filter media within the bioreactor.

[0014] The process may include periodically cleaning the mechanical filter device to remove solid waste accumulated in the fixed bed filter pack, which may include breaking down the fixed bed filter pack to expel solid waste accumulated in the mechanical filter element.

[0015] The waste outlet can be opened to discharge accumulated waste from the mechanical filter device. The accumulated waste can be discharged during a cleaning option. This process can include, for example, breaking the fixed-bed filter pack during a cleaning operation. Optionally, the mechanical filter device inlet can be opened to receive wastewater from the bioreactor, and the mechanical filter device outlet can be opened to discharge treated wastewater from the mechanical filter device.

[0016] The process may include introducing a pressurized fluid into the mechanical filter device to disrupt the fixed-bed filter pack. The fluid may be introduced at a pressure greater than atmospheric pressure. The fluid may be, for example, air or water. Alternatively, air may be drawn into the mechanical filter device as liquid is discharged from the mechanical filter device. Air may be introduced into the mechanical filter device periodically, such as during a cleaning operation to clean the mechanical filter elements. Alternatively or additionally, a backwash fluid may be introduced into the mechanical filter device to clean the mechanical filter elements.

[0017] The process may include opening a waste outlet of the mechanical filter device to discharge at least a portion of the accumulated solid waste from the mechanical filter device. At least a portion of the wastewater in the mechanical filter device may be discharged along with the accumulated solid waste. At least a portion of the accumulated solid waste from the mechanical filter device may be recirculated through the bioreactor. The solid waste may be removed from the mechanical filter element, for example, from the surface of the mechanical filter element and / or from one or more filter cells formed therein. At least a portion of the solid waste removed from the mechanical filter element may be recirculated through the bioreactor and subjected to further biological treatment. The accumulated solid waste may be introduced directly into the bioreactor or may be introduced upstream of the bioreactor. The accumulated solid waste may be introduced, for example, into a settling tank upstream of the bioreactor.

[0018] The process may include flocculating suspended material in the wastewater. The process may include using an electrocoagulation unit to flocculate suspended material in the wastewater. The electrocoagulation unit may be located upstream of the mechanical filter device. The flocculated material may be suspended in the wastewater introduced into the mechanical filter device.

[0019] An electrocoagulation unit may be located downstream of the bioreactor, the electrocoagulation unit being capable of agglomerating solid waste discharged from the bioreactor.

[0020] Solid waste may be removed from the surface of a biological filter element installed in the bioreactor. Alternatively, or in addition, an electrocoagulation unit may be incorporated into the mechanical filter device. Solid materials (typically particles) may be agglomerated within the mechanical filter device, thereby helping to ensure they remain intact. The electrocoagulation unit may include one or more electrodes to support the electrochemical process. The one or more electrodes may be disposed within the mechanical filter device, for example, within the filter chamber in which the fixed-bed filter pack is formed. The one or more electrodes may be at least partially surrounded by the mechanical filter element forming the fixed-bed filter pack. The one or more electrodes may be sacrificial electrodes. Agglomerating solid materials (typically particles) within the mechanical filter device can reduce disintegration or degradation of the agglomerated materials. At least one electrocoagulation unit can directly agglomerate materials onto the fixed-bed filter pack.

[0021] The process may include introducing a coagulant into the wastewater. The coagulant causes flocs to form in the wastewater. The flocs may include or consist of loosely aggregated particles or soft flakes. The coagulant may be introduced into the wastewater upstream of the mechanical filter device. Alternatively, or in addition, the coagulant may be introduced into the wastewater inside the mechanical filter device. For example, the coagulant may be introduced into a filter chamber in a mechanical filter device formed with a fixed-bed filter pack. The coagulant may be introduced directly into the filter chamber or at the inlet of the filter chamber. A coagulant injection system may be provided to supply the coagulant. The coagulant injection system may provide a metered injection of the coagulant. The coagulant may be introduced as a liquid or a solid, for example, as granules or a powder.

[0022] The coagulant may cause dissolved phosphates in the wastewater to come out of solution and form particles. The coagulant may be ferric chloride or polyaluminum sulfate (PAC). The coagulant may cause particles containing or consisting of phosphate to flocculate. The coagulant may cause particles containing or consisting of phosphate to flocculate and form flocs. At least a portion of the flocs may be suspended in the wastewater. A fixed-bed filter pack of a mechanical filter device may filter at least a portion of the particles, flocs, and flocs from the wastewater.

[0023] In at least certain embodiments, the flow rate of the wastewater through the mechanical filter device is substantially constant. The process may involve single-pass mechanical filtration of the wastewater in the mechanical filter device (i.e., the wastewater is passed through the mechanical filter device once). Alternatively, the process may involve multi-pass mechanical filtration of the wastewater in the mechanical filter device (i.e., the wastewater is passed through the mechanical filter device multiple times). A conduit may also be provided for recirculating the wastewater through the mechanical filter device.

[0024] This process involves reducing the flow rate per unit cross-sectional area of ​​a fixed-bed filter pack formed in a mechanical filter device to 0.1 m 3 / m 2 / h~19m 3 / m 2 / h, 5m 3 / m 2 / h~19m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 This may include setting the range to / h.

[0025] According to a further aspect of the present invention, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant including an inlet for receiving wastewater for treatment, a bioreactor including a biological filter medium for performing biological filtration of the wastewater, and a mechanical filter apparatus located downstream of the bioreactor, the mechanical filter apparatus comprising a fixed bed filter pack for filtering solid waste suspended in the wastewater, the fixed bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells, and an outlet for discharging the treated wastewater.

[0026] The mechanical filter device includes a plurality of mechanical filter elements. In use, the mechanical filter elements form a stationary filter pack that mechanically filters wastewater as it passes through the mechanical filter device. The mechanical filter device may include a filter tank that forms a filter chamber in which the mechanical filter elements are disposed. The filter cell or cells formed in each mechanical filter element have an open-cell structure. In use, wastewater flows into the filter cell or cells. Mechanical filtration occurs by promoting the settling of particles within the filter cell or cells.

[0027] The bioreactor can include a biological filter medium for biologically filtering the wastewater. The biological filter medium can include multiple biological filter elements for supporting colonies of microorganisms on the surface of the biological filter medium for biologically filtering the wastewater. The biological filter elements can be circulated within the bioreactor, i.e., forming a fluidized-bed biological filter. Alternatively, the biological filter elements can be stationary within the bioreactor, i.e., forming a fixed-bed biological filter. Other types of bioreactors are also contemplated. For example, the bioreactor may not include a biological filter medium.

[0028] In use, the fixed-bed filter pack of the mechanical filter device filters solid waste discharged from the bioreactor. The solid waste may be removed from the surface of the biological filter element in the bioreactor. The solid waste may be removed by contact between the biological filter elements in the fluidized bed. The solid waste may be removed as the biological filter elements form a fixed-bed biological filter. The solid waste may be removed from the biological filter element by other mechanical, hydraulic, or biological processes. The solid waste may be suspended in the wastewater discharged from the bioreactor.

[0029] The wastewater treatment plant can include a first settling tank for promoting settling of solids suspended in the wastewater, the first settling tank being located upstream of the bioreactor.

[0030] Alternatively, the wastewater treatment plant may additionally include a second settling tank downstream of the bioreactor to promote settling of solids suspended in the wastewater. The second settling tank may be disposed between the bioreactor and the mechanical filter device. Alternatively, the mechanical filter device may be disposed within the second settling tank. For example, the mechanical filter device may be disposed adjacent to the downstream outlet of the second settling tank. The wastewater may pass through the mechanical filter device upon being discharged from the second settling tank.

[0031] The wastewater treatment plant can optionally include a means for circulating the biological filter element within the bioreactor during filtration. This means can include a mechanical agitator disposed within the bioreactor. Alternatively, this means can include a pump for introducing pressurized liquid or air into the bioreactor. The pressurized liquid or air can circulate the biological filter media within the bioreactor. In use, circulation of the biological filter element can remove solid waste from the biological filter element and cause it to become suspended in the wastewater discharged from the bioreactor. In a variant, the wastewater treatment plant can include a pump for introducing air into the bioreactor to form a (submerged) fixed-bed biological filter comprising multiple biological filter elements.

[0032] The wastewater treatment plant may optionally include means for disrupting the fixed-bed filter packs in the mechanical filter device to discharge solid waste accumulated in the mechanical filter elements, which may include one or more of a pump for introducing pressurized air into the fixed-bed filter packs, a pump for introducing pressurized liquid into the fixed-bed filter packs, and a mechanical agitator for agitating the mechanical filter elements.

[0033] The wastewater treatment plant can include one or more valves for closing at least one of the mechanical filter device inlet and the mechanical filter device outlet while the fixed bed filter pack is being destroyed.

[0034] The wastewater treatment plant can include a pump for supplying pressurized fluid, e.g., water or air, to the mechanical filter device to break down the fixed-bed filter pack. The wastewater treatment plant can include a mechanical filter device waste outlet operable to discharge at least a portion of the solid waste accumulated within the mechanical filter device. The mechanical filter device waste outlet can be operable to discharge at least a portion of the solid waste removed from the mechanical filter element.

[0035] The wastewater treatment plant can include a return line configured to return at least a portion of the solid waste accumulated in the mechanical filter device to the bioreactor. The return line can be configured to introduce the waste into the bioreactor or upstream of the bioreactor. The return line can be connected to the bioreactor to return the solid waste removed from the mechanical filter element directly to the bioreactor. The return line can be connected to the first settling tank to return the solid waste accumulated in the mechanical filter device to the first settling tank.

[0036] The wastewater treatment plant may include at least one electrocoagulation unit for flocculating material suspended in the wastewater. The at least one electrocoagulation unit may be located upstream of the mechanical filter device. In use, the flocculated material may be suspended in the wastewater introduced into the mechanical filter device. The at least one electrocoagulation unit may be located downstream of the bioreactor. In use, the at least one electrocoagulation unit is operable to flocculate solid waste suspended in the wastewater discharged from the bioreactor.

[0037] Alternatively, or in addition, the at least one electrocoagulation unit may be integrated into the mechanical filter device. For example, the at least one electrocoagulation unit may be disposed within a filter chamber in which the mechanical filter element forms a fixed-bed filter pack. The at least one electrocoagulation unit may be at least partially surrounded by the mechanical filter element within the fixed-bed filter pack. The at least one electrocoagulation unit may directly coagulate material onto the fixed-bed filter pack.

[0038] The wastewater treatment plant may include at least one coagulant injection system for introducing a coagulant into the wastewater upstream of the mechanical filter device. The coagulant may cause flocs to form in the wastewater. The flocs may include or consist of loosely flocculated particles or soft flakes. In use, the coagulant may cause dissolved phosphates in the wastewater to come out of solution and form particles. The fixed-bed filter pack of the mechanical filter device may be configured to filter the particles or flocs formed by the coagulant. The coagulant may be ferric chloride or polyaluminum sulfate (PAC). Particles containing or consisting of phosphate may flocculate. In use, particles consisting of or consisting of phosphate may flocculate to form flocs. At least a portion of the flocs may be suspended in the wastewater. The fixed-bed filter pack of the mechanical filter device is configured to filter the flocs from the wastewater.

[0039] In at least certain embodiments, the flow rate of the wastewater through the mechanical filter device is substantially constant. The process can include single-pass mechanical filtration of the wastewater in the mechanical filter device (i.e., the wastewater is passed through the mechanical filter device once). Alternatively, the process can include multi-pass mechanical filtration of the wastewater in the mechanical filter device (i.e., the wastewater is passed through the mechanical filter device multiple times). A conduit can also be provided for recirculating the wastewater through the mechanical filter device.

[0040] The wastewater treatment plant may include at least one pump for pumping the wastewater through a mechanical filter device, the at least one pump being configured to pump a flow rate per unit cross-sectional area of ​​a fixed bed filter pack formed in the mechanical filter device of at least 0.1 m 3 / m 2 / h~19m 3 / m 2 / h, 5m 3 / m 2 / h~19m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 The frequency may be configured to be in the range of / h.

[0041] According to one aspect of the present invention, there is provided a wastewater treatment process for treating wastewater, the wastewater treatment process comprising the steps of receiving and treating wastewater; supplying the wastewater to a bioreactor including a biological filter medium for biologically filtering the wastewater, the biological filter medium including a plurality of biological filter elements for supporting colonies of microorganisms, the biological filter elements being circulated within the bioreactor during filtration, the circulation of the biological filter elements removing solid waste from the biological filter elements and suspending it in the wastewater; supplying the wastewater discharged from the bioreactor to a mechanical filter device disposed downstream of the bioreactor, the mechanical filter device including a fixed-bed filter pack for filtering the solid waste removed from the biological filter elements in the bioreactor and suspended in the wastewater, the fixed-bed filter pack including a plurality of mechanical filter elements, each having one or more filter cells; and discharging the treated wastewater.

[0042] It is recognized that the operation of a bioreactor generates solid waste, for example, including or consisting of solid particles or flocs. The flocs discharged from the bioreactor may contain clumps of flocculant. As the solid waste circulates through the bioreactor, it is dislodged from the surface of the biological filter media. In particular, the biological filter media come into contact with each other, causing the solid waste to be dislodged. The dislodged solid waste, for example, as solid particles, may be suspended in the wastewater discharged from the bioreactor. A mechanical filter device comprising a fixed-bed filter pack formed by multiple mechanical filter elements has been determined to be particularly effective in removing suspended solid waste in the wastewater discharged from the bioreactor. In at least certain embodiments, a series combination of a bioreactor and a mechanical filter device has been determined to be particularly effective in treating wastewater. The wastewater may be, for example, industrial or municipal wastewater.

[0043] Bioreactors can be anaerobic or aerobic. Anaerobic bioreactors are configured to support anaerobic microorganisms. Aerobic bioreactors are configured to support aerobic microorganisms. Aerobic bioreactors are configured, for example, to introduce air into the wastewater to support aerobic microorganisms.

[0044] Each mechanical filter element has one or more filter cells. The structure of the mechanical filter element is referred to herein as an open-cell structure. The filter element is non-porous. The sidewalls of the or each filter cell are non-porous. Each of the one or more filter cells has an opening formed in the mechanical filter element. The filter element can be molded, for example, from a plastic material.

[0045] The or each filter cell can have a cross-sectional area ranging from one (1) to ten (10) square millimeters, or from one (1) to five (5) square millimeters. The filter cells can have lengths of five millimeters, six millimeters, eight millimeters, or more. The mechanical filter element can be negatively buoyant, neutrally buoyant, or positively buoyant.

[0046] The wastewater treatment step may include feeding the wastewater to a settling tank located upstream of the bioreactor for settling of solids. The wastewater from the settling tank can be fed to the bioreactor.

[0047] The wastewater treatment process may include introducing a pressurized fluid into the bioreactor to circulate the biological filter media within the bioreactor. The fluid may be a liquid or a gas. The wastewater treatment process may also include introducing pressurized air into the bioreactor to circulate the biological filter media within the bioreactor. Alternatively, or in addition, a mechanical agitator may be used to circulate the biological filter media within the bioreactor. The mechanical agitator may, for example, comprise one or more rotating members.

[0048] The wastewater treatment process may include periodically cleaning the mechanical filter device to remove solid waste accumulated in the fixed-bed filter pack. Cleaning the mechanical filter device may include breaking down the fixed-bed filter pack to remove solid waste accumulated in the mechanical filter element. The method may include breaking down the fixed-bed filter pack 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. Cleaning may include breaking down the fixed-bed filter pack for a predetermined period of time.

[0049] The fixed-bed filter pack can be disrupted using one or more mechanical cleaning elements. The one or more mechanical cleaning elements can be driven by an electric motor or the like. For example, the one or more mechanical cleaning elements can be rotated within the mechanical filter device. Alternatively, or in addition, a fluid can be introduced into the mechanical filter device to disrupt the fixed-bed filter pack. The fluid can be a liquid or a gas. The fluid can be introduced at a pressure higher than atmospheric pressure. The fluid can be air. An air pump can be provided to supply pressurized air to the mechanical filter device.

[0050] The wastewater treatment step can include opening a waste outlet of the mechanical filter device to discharge at least a portion of the wastewater in the mechanical filter device together with the solid waste removed from the mechanical filter element. The waste outlet of the mechanical filter device can be opened after the fixed-bed filter pack has been destroyed for a predetermined period of time.

[0051] The wastewater treatment process can include recirculating at least a portion of the wastewater through a bioreactor. At least a portion of the solid waste removed from the mechanical filter element in the mechanical filter device can be reintroduced upstream of the bioreactor. This allows the solid waste accumulated in the mechanical filter device to undergo further biological filtration. The solid waste removed from the mechanical filter element can be introduced directly into the bioreactor. Alternatively, the solid waste removed from the mechanical filter element can be introduced upstream of the bioreactor, for example, into a settling tank (if present in the system).

[0052] The removed solid waste is preferably transported with the wastewater discharged from the mechanical filter device. Alternatively, or in addition, the removed solid waste can be transported with another liquid supply, such as a wash liquid.

[0053] The wastewater treatment process may include using an electrocoagulation unit to flocculate suspended matter in the wastewater. The electrocoagulation unit may be located upstream of a mechanical filter device. The flocculated matter may be suspended in the wastewater that is introduced into the mechanical filter device. In at least certain embodiments, the mechanical filter device operates to remove the flocculated matter from the wastewater.

[0054] An electrocoagulation unit can be positioned downstream of the bioreactor and can operate to flocculate solid waste removed from the biological filter element within the bioreactor, which can then be removed by a mechanical filter device.

[0055] According to a further aspect of the present invention, there is provided a wastewater treatment process for treating wastewater, the wastewater treatment process comprising the steps of receiving and treating the wastewater; supplying the wastewater to a bioreactor including a biological filter medium for biological filtration of the wastewater, the biological filter medium including a plurality of biological filter elements for supporting colonies of microorganisms, the biological filter elements being circulated within the bioreactor during filtration, the circulation of the biological filter elements removing solid waste from the biological filter elements and suspending it in the wastewater; supplying the wastewater discharged from the bioreactor to an electrocoagulation device to coagulate the solid waste removed from the biological filter elements in the bioreactor; and discharging the treated wastewater.

[0056] The microorganisms can be aerobic or anaerobic. The biological filter elements can be continuously circulated within the bioreactor to maintain appropriate ambient conditions to support the microorganisms within the bioreactor.

[0057] According to a further aspect of the present invention, there is provided a wastewater treatment process for treating wastewater, the wastewater treatment process comprising the steps of receiving and treating the wastewater; supplying the wastewater to an electrocoagulation device to coagulate solids suspended in the wastewater; supplying the wastewater from the electrocoagulation unit to a mechanical filter device, the mechanical filter device comprising a fixed bed filter pack for filtering the coagulated solids from the electrocoagulation unit, the fixed bed filter pack comprising a plurality of mechanical filter elements, each having one or more filter cells; and discharging the treated wastewater.

[0058] According to a further aspect of the present invention, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising: an inlet for receiving wastewater for treatment; a bioreactor comprising a biological filter medium for performing biological filtration of the wastewater, the biological filter medium being suitable for supporting a colony of microorganisms, the bioreactor including means for circulating the biological filter medium within the bioreactor during filtration; and a mechanical filter apparatus located downstream of the bioreactor, the mechanical filter apparatus comprising a fixed bed filter pack for filtering solid waste dislodged from the biological filter element in the bioreactor and suspended in the wastewater, the fixed bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and an outlet for discharging the treated wastewater.

[0059] Microorganisms include aerobic microorganisms, anaerobic microorganisms, and anoxic microorganisms.

[0060] Each mechanical filter element comprises one or more filter cells. The mechanical filter elements are non-porous. The or each filter cell has a non-porous sidewall. Each of the one or more filter cells comprises an opening formed in the mechanical filter element. The mechanical filter elements can be molded, for example, from a plastic material.

[0061] The wastewater treatment plant may include a settling tank to promote settling of solids suspended in the wastewater, the settling tank being located upstream of the bioreactor.

[0062] The wastewater treatment plant can include a pressurized air supply for introducing pressurized air into the bioreactor for circulating the biological filter media within the bioreactor.

[0063] The wastewater treatment plant may include an air pump for generating a pressurized air supply. The wastewater treatment plant may include means for breaking up fixed-bed filter packs within the mechanical filter device to expel solid waste accumulated in the open-cell filter media. The breaking up means may include a mechanical member or an agitation mechanism for breaking up the fixed-bed filter packs. Alternatively, or in addition, the breaking up means may include a pump or compressor for supplying pressurized fluid into the mechanical filter device. The fluid may include a liquid or a gas. The pump or compressor may supply pressurized air to the mechanical filter device.

[0064] The wastewater treatment plant can include one or more valves for closing at least one of the mechanical filter device inlet and the mechanical filter device outlet. At least one of the mechanical filter device inlet and / or the mechanical filter device outlet can be closed while the fixed bed filter pack is being destroyed for cleaning.

[0065] The wastewater treatment plant may include a pump for introducing pressurized air or liquid into the mechanical filter device to break down the fixed bed filter pack. Alternatively, or in addition, the wastewater treatment plant may include a mechanical agitator to break down the fixed bed filter pack.

[0066] The wastewater treatment plant can include a mechanical filter unit wastewater outlet operable to discharge at least a portion of the wastewater within the mechanical filter unit.

[0067] The wastewater treatment plant may include a return line configured to return at least a portion of the wastewater and / or accumulated waste from the mechanical filter device for reintroduction into the wastewater treatment plant upstream of the bioreactor. The return line may be connected to the bioreactor to return the wastewater and / or accumulated waste from the mechanical filter device to the bioreactor. The return line may be connected to a settling tank to return the wastewater from the mechanical filter device to the settling tank upstream of the bioreactor. The water from the settling tank may then be discharged into the bioreactor.

[0068] The wastewater treatment plant may include an electrocoagulation unit that flocculates suspended matter in the wastewater.

[0069] The electrocoagulation unit may be located upstream of the mechanical filter device. In use, the flocculants are suspended in wastewater and introduced into the mechanical filter device.

[0070] The electrocoagulation unit may be located downstream of the bioreactor and, in use, may operate to flocculate solid waste suspended in wastewater discharged from the bioreactor.

[0071] According to a further aspect of the present invention, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant comprising an inlet for receiving wastewater for treatment, a bioreactor comprising a biological filter medium for performing biological filtration of the wastewater, the biological filter medium being suitable for supporting a colony of microorganisms, the bioreactor comprising means for circulating the biological filter medium within the bioreactor during filtration, and an electrocoagulation unit located downstream of the bioreactor, the electrocoagulation unit configured to flocculate material suspended in wastewater discharged from the bioreactor.

[0072] According to a further aspect of the present invention, there is provided a wastewater treatment plant for treating wastewater, the wastewater treatment plant including an inlet for receiving wastewater for treatment, an electrocoagulation device for coagulating solids suspended in the wastewater, and a mechanical filter device located downstream of the electrocoagulation unit, the mechanical filter device comprising a fixed bed filter pack for filtering coagulated solid material discharged from the electrocoagulation unit and suspended in the wastewater, the fixed bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells, and an outlet for discharging the treated wastewater.

[0073] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives, particularly individual features thereof, described in the preceding paragraphs, claims, and / or the following description and drawings, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment may be combined in any manner and / or combination, except where such features are incompatible. The applicant reserves the right to modify the originally filed claims or to submit new claims accordingly, including the right to amend the originally filed claims to depend on and / or incorporate features of other claims, even though not originally claimed as such. [Brief explanation of the drawings]

[0074] One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of a water treatment plant according to one embodiment of the present invention. [Figure 2A] FIG. 2A is a perspective view of a mechanical filter element used in the filtration system of the water treatment plant shown in FIG. [Figure 2B] FIG. 2B is an end view of the mechanical filter element shown in FIG. 2A. [Figure 2C]FIG. 2C is a perspective view showing a modification of the mechanical filter element shown in FIG. 2A. [Figure 3] FIG. 3 is a first flow diagram illustrating the operation of the wastewater treatment plant shown in FIG. [Figure 4] FIG. 4 is a schematic diagram of a further embodiment of a water treatment plant according to the invention. [Figure 5] FIG. 5 is a schematic diagram illustrating a further embodiment of a water treatment plant according to the invention. [Figure 6] FIG. 6 is a schematic diagram of a further embodiment of a water treatment plant according to the invention. [Figure 7] FIG. 7 is a second flow diagram illustrating the operation of the wastewater treatment plant shown in FIG. [Figure 8] FIG. 8 is a schematic diagram of a further embodiment of a water treatment plant according to the present invention incorporating first and second chemical injection systems. [Figure 9] FIG. 9 is a schematic diagram of a further embodiment of a water treatment plant according to the present invention incorporating three chemical injection systems. [Figure 10A] FIG. 10A shows an example of a filter vessel suitable for a mechanical filter device according to the present invention. [Figure 10B] FIG. 10B shows an example of a filter chamber suitable for a mechanical filter device according to the present invention. [Figure 10C] FIG. 10C shows an example of a filter chamber suitable for a mechanical filter device according to the present invention. [Figure 10D] FIG. 10D shows an example of a filter chamber suitable for a mechanical filter device according to the present invention. [Figure 10E] FIG. 10E shows an example of a filter chamber suitable for a mechanical filter device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0075] A method and apparatus for treating wastewater according to one embodiment of the present invention will now be described with reference to the accompanying drawings. The wastewater in this embodiment is municipal wastewater. Alternatively, or in addition, the wastewater treatment plant and process may be used to treat industrial wastewater.

[0076] Next, a wastewater treatment plant 1 according to this embodiment will be described. The wastewater treatment plant 1 is an urban wastewater treatment plant configured to purify urban wastewater. As described herein, the wastewater treatment plant 1 employs physical and biological methods to purify the wastewater. Optionally, the wastewater treatment plant 1 may also use chemical methods to purify the wastewater. The wastewater treatment plant 1 purifies the wastewater to remove pollutants or toxins that, if released, could cause environmental degradation. The wastewater treatment plant 1 can also remove dissolved nutrients, such as nitrogen, to reduce or prevent eutrophication of waterways. Nitrogen can be removed through a denitrification process, which converts ammonia to nitrate. In certain embodiments, the wastewater treatment plant 1 can be used to treat industrial wastewater, which has higher toxicity than urban wastewater. The wastewater treatment plant 1 may include pretreatment facilities (not shown) or posttreatment facilities suitable for treating industrial wastewater, for example, to remove toxins.

[0077] As shown in Figure 1, wastewater treatment plant 1 includes a wastewater inlet 3, a wastewater outlet 5, and a waste outlet 7. Wastewater inlet 3 is configured to receive influent wastewater. Wastewater outlet 5 is configured to discharge wastewater after treatment by wastewater treatment plant 1. Waste outlet 7 discharges waste materials removed from the wastewater. Wastewater discharged from wastewater treatment plant 1 through waste outlet 7 can undergo further treatment. Alternatively, at least a portion of the waste materials can be recycled to wastewater treatment plant 1 for further treatment.

[0078] The wastewater treatment plant 1 includes a settling tank 11, a bioreactor 13, a mechanical filter device 15, and at least one air pump 17. As described herein, the bioreactor 13 is configured to perform biological filtration of wastewater. In this embodiment, the bioreactor 13 is a fluidized-bed bioreactor, although other types of bioreactors are contemplated. The mechanical filter device 15 is configured to perform mechanical filtration to remove particles suspended in the wastewater discharged from the bioreactor 13. The settling tank 11, the bioreactor 13, and the mechanical filter device 15 are connected in series. The wastewater passes through the settling tank 11, the bioreactor 13, and the mechanical filter device 15, in that order. Specifically, the influent wastewater is introduced into the settling tank 11 for primary settling. The wastewater discharged from the settling tank 11 is introduced into the bioreactor 13 for biological filtration. The wastewater discharged from the bioreactor 13 is introduced into the mechanical filter device 15 for mechanical filtration. The wastewater is discharged from the wastewater treatment plant 1 after passing through the mechanical filter device 15. One or more water pumps (not shown) may be provided to pump the wastewater through the wastewater treatment plant 1. At least one air pump 17 is provided to supply air at a pressure higher than atmospheric pressure to the bioreactor 13 and the mechanical filter device 15. In this embodiment, the wastewater treatment plant 1 includes a single air pump 17 and first and second control valves 19-1 and 19-2 that control the supply of pressurized air to at least one of the bioreactor 13 and the mechanical filter device 15, respectively. The wastewater treatment plant 1 includes an electronic control unit ECU1 that includes at least one electronic processor 21 and a 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 and 19-2 to control the supply of pressurized air from the air pump 17 to the bioreactor 13 and the mechanical filter device 15.Alternatively, separate air pumps 17 may be provided to supply air to the bioreactor 13 and the mechanical filter device 15, respectively.

[0079] The settling tank 11 includes at least one settling tank inlet 31, at least one settling tank outlet 33, and at least one settling tank waste outlet 35. As shown in FIG. 1 , the at least one settling tank inlet 31 and the at least one settling tank outlet 33 are located in an upper region of the settling tank 11. The at least one settling tank waste outlet 35 is located in a 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, influent wastewater is introduced into the settling tank 11 through the at least one settling tank inlet 31. Solids settle from the wastewater and sink 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 bioreactor 13. The settling tank 11 thereby functions as a prefilter for the bioreactor 13. At least one settling tank waste valve 37 is provided to control 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. At least one settling tank waste valve 37 is selectively opened to release the accumulated waste. The waste discharged from the at least one settling tank 11 is sent for disposal or further processing. 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.

[0080] 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 a lower region of the bioreactor 13, and the at least one bioreactor outlet 43 is located in an upper region of the bioreactor 13. This arrangement is suitable for the bioreactor 13 of this embodiment in which an upward flow of wastewater is established. The relative positions of the at least one bioreactor inlet 41 and the at least one bioreactor outlet 43 can be reversed if the bioreactor 13 is configured to establish a downward flow of wastewater. The bioreactor 13 performs biological filtration of the wastewater. In particular, the bioreactor 13 includes a biological filter chamber 47 containing a biological filter medium 49 for biologically filtering wastewater. The biological filter medium 49 includes a plurality of biological filter elements 51. The inner and outer surfaces of the biological filter elements 51 are suitable for supporting colonies of microorganisms. The microorganisms are effective at converting organic matter present in the wastewater. The open-cell morphology of the biological filter elements 51 in this embodiment provides an increased surface area for supporting the microorganisms. The microorganisms in this embodiment are aerobic. Alternatively, the bioreactor 13 may be configured to support anaerobic or anoxic microorganisms. A biofilm may form on the surface of the biological filter element 51. Other types of bioreactors 13 are also contemplated. For example, the bioreactor 13 may include a fixed-bed bioreactor 13. The bioreactor 13 may include, for example, a submerged aerated filter (SAF). The biological filter elements 51 form a continuously aerated bed. The biological filter elements 51 are at least substantially stationary within the bed. The biological filter element 51 may be held in place by one or more screens.The submerged aeration filter may include an integrated settling tank, for example in the form of a settling tank formed before the outlet of the submerged aeration filter. In a variant, the bioreactor 13 may not include a biological filter medium. For example, activated sludge from downstream of the bioreactor 13 may be reintroduced into the bioreactor 13. The activated sludge may be introduced directly into the bioreactor 13 or may be introduced upstream of the bioreactor 13.

[0081] 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 moves continuously within the bioreactor 13 (a so-called fluidized-bed bioreactor). To circulate the biological filter medium 49, a fluid can be introduced into the biological filter chamber 47 under pressure. The circulation of the biological filter medium 49 is illustrated in FIG. 1 by a curved line with arrows indicating the flow direction. The fluid can be a liquid or a gas. In this embodiment, pressurized air is introduced into the biological filter chamber 47 to circulate the biological filter medium 49 within the biological filter chamber 47. The air pump 17 is configured to supply pressurized air to at least one bioreactor air inlet 45. In a 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 in addition, a mechanical agitator, e.g., comprising one or more rotating members, can be provided to circulate the biological filter media 49 within the biological filter chamber 47. The use of an agitation mechanism is appropriate, for example, when the bioreactor 13 is configured to support anaerobic microorganisms.

[0082] The bioreactor 13 includes a biological filter medium 49 that includes a plurality of biological filter elements 51. The filter medium 49 typically occupies at least 30% (by volume) of the filter chamber. The filter medium 49 can occupy up to seventy percent (70%) of the filter chamber by volume. In this embodiment, the filter medium 49 occupies approximately 50% (by volume) of the filter chamber. The biological filter elements 51 support a colony of microorganisms that decompose waste materials. The influent enters the biological filter chamber 47 for treatment. The biological filter elements 51 function as a biological carrier that supports a colony of microorganisms. The microorganisms typically form a biofilm on at least a portion of the surface of the biological filter elements 51. A ventilation grid (not shown) can be provided to introduce air into the biological filter chamber 47. The ventilation grid may, for example, comprise one or more tubular members having a plurality of openings through which air can be introduced into the biological filter chamber 47. In use, the air pump 17 can supply pressurized air to the ventilation grid. The ventilation grid is typically located in the lower portion of the biological filter chamber 47. The air moves the biological filter element 51 within the biological filter chamber 47 (forming a fluidized bed), thereby promoting contact with the waste. The introduction of air into the biological filter chamber 47 also introduces oxygen into the biological filter chamber 47, promoting aerobic activity. A screen (not shown) is provided above the bioreactor outlet 43 to retain the biological filter element 51 within the biological filter chamber 47.

[0083] The biological filter media 49 is preferably continuously circulated within the biological filter chamber 47 during filtration. It is recognized that circulation of the biological filter elements 49 within the biological filter chamber 47 may dislodge solid material from the biological filter elements 49. Circulation of the biological filter media 49 may cause the biological filter elements 51 to contact one another, which may dislodge solid material from the surface of the biological filter elements 51 or from within the open cells of the biological filter elements 51. The solid material dislodged from the biological filter elements 51 may be in the form of flocs or agglomerated flocs. The dislodged solid material may comprise, for example, flocs. The dislodged solid material may include or consist of solid particles having a diameter of ten (10) micrometers or less (i.e., <10 pm) and potentially five (5) micrometers or less (i.e., <5 pm). The dislodged solid particles from the biological filter elements 51 include solid particles held in suspension.

[0084] After biological filtration, the wastewater is discharged from the bioreactor 13 through at least one bioreactor outlet 43 and introduced into the mechanical filter device 15. The mechanical filter device 15 is configured to perform mechanical filtration of the wastewater to remove at least a portion of solid particles suspended in the wastewater discharged from the bioreactor 13. The mechanical filter device 15 comprises a mechanical filter tank 60, at least one mechanical filter inlet 61, at least one mechanical filter outlet 63, at least one mechanical filter air inlet 65, and at least one mechanical filter waste outlet 67. The at least one mechanical filter inlet 61 is in fluid communication with the at least one bioreactor outlet 43. In use, the wastewater from the bioreactor 13 is introduced into the mechanical filter device 15 through the at least one mechanical filter inlet 61. The at least one mechanical filter inlet 61 is located in a lower region of the mechanical filter device 15, and the at least one mechanical filter outlet 63 is located in an upper region of the mechanical filter device 15. This arrangement is suitable for the mechanical filter device 15 of this embodiment in which an upward flow of wastewater is established. The relative positions of the at least one mechanical filter inlet 61 and the at least one mechanical filter outlet 63 can be reversed if the mechanical filter device 15 is configured to establish a downward flow of wastewater. The mechanical filter device 15 performs mechanical filtration of the wastewater. In particular, the mechanical filter device 15 includes a mechanical filter chamber 70 including a mechanical filter medium 69 for performing mechanical filtration of the wastewater. The wastewater supplied to the mechanical filter device 15 is filtered by the mechanical filter medium 69 to remove at least a portion of the solid particles suspended in the wastewater supplied from the bioreactor 13. The treated wastewater is discharged from the mechanical filter device 15 through the at least one mechanical filter outlet 63.

[0085] The mechanical filter media 69 includes a plurality of mechanical filter elements 71. The mechanical filter elements 71 in this embodiment have an open-cell structure. Schematic diagrams of one mechanical filter element 71 are shown in FIGS. 2A and 2B. A perspective view of one variation of the mechanical filter element 71 is shown in FIG. 2C. The dimensions of the mechanical filter element 71 are shown in FIG. 2C as an example. The dimensions shown have a tolerance of ±1 mm. The inner wall of the mechanical filter element 71 has a thickness of approximately 0.75 mm to 1 mm. The outer periphery of the mechanical filter element 71 is formed with a plurality of external ribs. The radial length of the ribs is approximately 0.5 mm to 1 mm. It will be understood that mechanical filter elements 71 with different dimensions can be used in the wastewater treatment plant 1 described herein. The mechanical filter elements 71 have a non-porous structure, each including one or more filter cells 73. The mechanical filter element 71 includes walls (inner and outer) that form one or more filter cells 73. The walls are impermeable and prevent liquid flow between adjacent filter cells 73. Each of the one or more filter cells 73 has a substantially uniform profile along the length of the mechanical filter element 71. Each of the one or more filter cells 73 is open at each end. In this embodiment, each of the filter cells 73 has a cross-sectional area ranging from one (1) to five (5) square millimeters and a length of six (6) millimeters or more. A fixed filter pack 75 comprising open-cell filter media 69 is formed within the mechanical filter chamber 70. The mechanical filter element 71 of this embodiment is positively buoyant in water. The mechanical filter element 71 floats within the mechanical filter chamber 70, forming a fixed-bed filter pack 75 in the upper region of the mechanical filter chamber 70. In an alternative embodiment, the mechanical filter element 71 can be negatively buoyant and form a fixed-bed filter pack 75 in the lower region of the mechanical filter chamber 70. The mechanical filter element 71 is effective at filtering wastewater by promoting the settling of suspended solid particles within the wastewater.The solid particles settle within the filter cells 73 and on the surface of the mechanical filter element 71. The mechanical filter element 71 is formed in this embodiment by extruding a polymer. Other techniques for forming the mechanical filter element 71 can also be used.

[0086] The mechanical filter device 15 is periodically cleaned to drain solids accumulated within the mechanical filter chamber. Cleaning the mechanical filter device 15 involves closing at least one mechanical filter inlet 61 and at least one mechanical filter outlet 63. The mechanical filter waste outlet 67 is closed during the cleaning operation and then opened to purge (or drain) the mechanical filter device 15. In this embodiment, a mechanical filter inlet valve 77 is provided to open and close the at least one mechanical filter inlet 61, and a mechanical filter outlet valve 79 is provided to open and close the at least one mechanical filter outlet 63. A mechanical filter waste valve 81 is provided to open and close the mechanical filter waste outlet 67. The mechanical filter inlet and outlet valves 77, 79 are both 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.

[0087] Next, the second control valve 19-2 is opened, supplying pressurized air into the mechanical filter chamber 70. The pressurized air is introduced into the mechanical filter chamber 70 to disassemble the fixed-bed filter pack 75 and agitate the mechanical filter element 71. The mechanical filter device 15 may be open to the atmosphere, or a vent (not shown) may be open. This allows accumulated waste to be discharged from the mechanical filter element 71. The supply of pressurized air continues for a predetermined period of time, which can be determined, for example, by empirical analysis. Thereafter, the mechanical filter waste valve 81 is opened to open the mechanical filter waste outlet 67, allowing the wastewater in the mechanical filter chamber 70 to be discharged. The supply of pressurized air can optionally continue even after the mechanical filter waste outlet 67 is opened. A portion of the wastewater discharged from the mechanical filter chamber 70 can be returned for further treatment in the wastewater treatment plant 1. In this embodiment, a waste return line 83 is provided to return the wastewater discharged from the mechanical filter device 15. A waste control valve 85 may optionally be provided to control the supply of wastewater to the waste return line 83. In this embodiment, a portion of the wastewater that accumulates in the mechanical filter chamber 70 is returned to the settling tank 11 or bioreactor 13, thereby allowing a portion of the wastewater to be recycled within the wastewater treatment plant 1. A portion of the wastewater discharged from the mechanical filter chamber 70 can optionally be sent to waste or for further treatment.

[0088] After the mechanical filter chamber 70 has been drained, the mechanical filter waste valve 81 is closed and the mechanical filter waste outlet 67 is closed. The supply of pressurized air to the mechanical filter chamber 70 is stopped by closing the second control valve 19-2. The at least one mechanical filter inlet 61 and the at least one mechanical filter outlet 63 are then opened to re-establish the flow of wastewater through the mechanical filter apparatus 15.

[0089] In use, the mechanical filter elements 71 form a fixed bed filter pack 75 that operates to filter solids from wastewater. The mechanical filter elements 71 can have positive, negative, or neutral buoyancy. The mechanical filter elements 71 have an open cell structure that provides a high retention capacity. The flow rate per unit cross-sectional area of ​​the fixed bed filter pack 75 is typically 20 m 3 / m 2 / h, for example, less than 0.1 m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 1 1m 3 / m 2 / h~19m 3 / m 2 / h. These flow rates per unit cross-sectional area have been recognized to be particularly effective for removing flocs (also known as aggregates) from wastewater. Flocs may include or consist of loosely agglomerated particles or soft flakes. In at least certain embodiments, the flocs may settle within or outside the filter cells 73 of the mechanical filter element 71. A relatively low flow rate through the fixed-bed filter pack 75 helps reduce or avoid floc breakup. Higher flow rates may cause some flocs to break down or disintegrate into smaller flocs or individual particles. In at least certain embodiments, the wastewater treatment plant 1 can capture very fine particles suspended in the wastewater. Treated water from the mechanical filter device 15 is discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water may be sent downstream for further treatment.

[0090] The operation of a wastewater treatment plant 1 for treating wastewater is illustrated in a first flow diagram 100 shown in FIG. 3. Wastewater to be treated is received as influent wastewater at the wastewater treatment plant 1 (block 105). The wastewater is optionally introduced into a settling tank 11 to facilitate settling of solids (block 110). The wastewater is discharged from the settling tank 11 to a bioreactor 13 (block 115). The bioreactor 13 performs biological filtration of the wastewater, and biologically filtered water is discharged from the bioreactor (block 120). Movement of the biological filter element introduces solid particles, including or consisting of flocs, into suspension in the wastewater discharged from the bioreactor 13. The wastewater is fed from the bioreactor 13 to a mechanical filter device 15 (block 125). The wastewater discharged from the bioreactor 13 typically comprises particles suspended in the wastewater. The particles may combine to form flocs that are suspended in the wastewater. Flocs may be formed from loosely agglomerated particles. The mechanical filter device 15 mechanically filters the wastewater to remove at least a portion of the solid particles held in suspension (Block 130). The treated wastewater (effluent) is discharged from the mechanical filter device 15 (Block 135). The mechanical filter device 15 is periodically cleaned (Block 140). Cleaning may include breaking up the fixed-bed filter pack 75 by, for example, introducing a fluid such as air to break up the fixed-bed filter pack 75 (Block 145). Accumulated solid waste is removed from the fixed-bed filter pack and discharged from the mechanical filter device 15 (Block 150). At least a portion of the solid waste from the mechanical filter device 15 is returned through the waste return line 83 and passed through the bioreactor 13 again (Block 155). The process continues (Block 160).

[0091] The wastewater treatment plant 1 according to the above embodiment has been described with one primary settling tank 11, one bioreactor 13, and one mechanical filter device 15. This is merely an example, and the wastewater treatment plant 1 may be configured to include one or more of each of the primary settling tank 11, the bioreactor 13, and the mechanical filter device 15. For example, one or more bioreactors 13 may be provided. Furthermore, multiple bioreactors 13 may be connected in parallel or in series. One or more primary settling tanks 11 may be provided upstream of one or more bioreactors 13. Multiple primary settling tanks 11 may be connected upstream of the bioreactors 13 in parallel or in series. One or more tertiary settling tanks 20 may be provided downstream of one or more bioreactors 13. Multiple tertiary settling tanks 20 may be connected downstream of the bioreactors 13 in parallel or in series. A pump (not shown) may be provided to pump accumulated waste from the wastewater treatment plant 1, for example, from the primary settling tank 11 and / or the tertiary settling tank 20.

[0092] The wastewater treatment plant 1 according to the above embodiment is described with reference to a bioreactor 13 equipped with a fluidized bed biofilm bioreactor (MBBR). Other types of bioreactors 13 are also contemplated for the wastewater treatment plant 1. The bioreactor 13 can be configured to perform aerobic, anaerobic, or anaerobic biological filtration of wastewater. Aerobic biological filtration is performed by microorganisms that require oxygen. Anaerobic biological filtration is performed by microorganisms that require little or no oxygen (<0.5 mg / L or <0.2 mg / L). Anoxic biological filtration is performed by microorganisms that release bound oxygen (such as nitrites / nitrates), thereby reducing or eliminating the need to introduce air to aerate the wastewater.

[0093] As outlined above, some of the accumulated waste can be reintroduced into the bioreactor 13 in the form of activated sludge. Activated sludge contains high concentrations of microorganisms, including bacteria, protozoa, and fungi, present as a loose mass of fine particles. This mass is kept in suspension by agitation (anaerobic systems) or air (aerobic systems) in order to remove organic matter from the wastewater. This process is commonly referred to as recirculating activated sludge (RAS).

[0094] The bioreactor 13 can comprise an integrated fixed film activated sludge (IFAS). This process is similar to the fluidized bed biofilm carrier treatment process (MBBR) described herein. For example, activated sludge accumulated in a tertiary settling tank is introduced into a filter chamber containing a filter medium. The filter medium and activated sludge may both be present in the same filter chamber. The filter chamber may include an anoxic zone and an aerobic zone. The activated sludge is introduced into the anoxic zone, and a fluidized bed bioreactor is established in the aerobic zone by, for example, introducing air to agitate the filter medium.

[0095] The bioreactor 13 may comprise a sequencing batch reactor (SBR) that uses both aerobic and anaerobic processes in a timed sequence. The SBR is capable of both nitrification and denitrification. A steady, constant inflow is fed to the filter chamber. The filter chamber is aerated to promote the aerobic reaction. The air supply is then stopped to promote settling. The water in the filter chamber is then gently decanted as wastewater. The waste remaining in the filter chamber is drained and disposed of. This process can also be combined with chemical coagulants to remove phosphates. The wastewater discharged from the filter tank can also undergo further biological treatment.

[0096] The bioreactor 13 may comprise a membrane bioreactor (MBR). An MBR 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. The result is a highly treated wastewater suitable for reuse or discharge into the environment.

[0097] The bioreactor 13 may include a submerged aerated filter (SAF). The biological filter element may be held in a fixed bed submerged in the wastewater. The biological filter element is aerated to promote aerobic biological filtration.

[0098] Wastewater can be subjected to other types of mechanical and / or biological filtration, such as (i) dissolved air flotation (DAF), which suspends particles at the surface of the water, for example by weirs, facilitating their removal, or (ii) lamellar separators in the form of angled plates that slow the flow of the liquid and promote the settling of particles for collection and removal by sludge pumps.

[0099] A mechanical filter device 15 of the type described herein can be provided upstream of the bioreactor 13. For example, the mechanical filter device 15 can be provided between the primary sedimentation tank 11 and the bioreactor 13.

[0100] Next, a modified example of the wastewater treatment plant 1 according to the above embodiment will be described with reference to Fig. 4. Note that like reference numerals are used to denote like components. The following description will focus on the differences between the wastewater treatment plant 1 according to this embodiment and the embodiment described with reference to Fig. 1.

[0101] The wastewater treatment plant 1 comprises a primary sedimentation tank 11, a bioreactor 13, and a mechanical filter device 15. The wastewater treatment plant 1 may optionally comprise a tertiary sedimentation tank 20. The tertiary settling tank 20 can be disposed between the bioreactor 13 and the mechanical filter device 15. The wastewater treatment plant 1 also includes a primary screen 9 disposed upstream of the primary settling tank 11. The primary screen 9 is configured to filter relatively large debris and detritus from the influent supplied to the wastewater treatment plant 1. The primary screen 9 includes a plurality of openings through which the wastewater passes to remove debris. The primary screen 9 can include, for example, a sieve, mesh, or membrane. After being filtered by the primary screen 9, the wastewater is introduced into the primary settling tank 11. At least a portion of the debris that passes through the primary screen 9 settles from a suspended state within the primary settling tank 11. The waste accumulated in the primary settling tank 11 is discharged through the primary settling tank waste outlet 11a and disposed of. A valve (represented by a valve symbol) can be provided at the primary settling tank waste outlet 11a.

[0102] The bioreactor 13 may comprise a fluidized bed bioreactor (MBBR) of the type described herein. In this embodiment, the bioreactor 13 comprises a fixed-bed bioreactor 13. The bioreactor 13 may comprise, for example, a submerged aerated filter (SAF). The biological filter element 51 forms a continuously aerated bed. The biological filter element 51 is at least substantially stationary within the bed. The biological filter element 51 may be held in place by one or more screens. The submerged aeration filter may include an integrated settling tank, for example, in the form of a settling tank formed before the outlet of the submerged aeration filter. In a variant, the bioreactor 13 may not include a biological filter medium. For example, activated sludge from downstream of the bioreactor 13 may be reintroduced into the bioreactor. The activated sludge may be introduced directly into the bioreactor 13 or upstream of the bioreactor 13. Other types of bioreactors 13 are also contemplated.

[0103] The mechanical filter device 15 is configured to perform mechanical filtration of wastewater discharged from the bioreactor 13 to remove at least a portion of solid particles suspended in the wastewater. The mechanical filter device 15 includes a mechanical filter chamber 60, at least one mechanical filter inlet 61, at least one mechanical filter outlet 63, at least one mechanical filter air inlet 65, and at least one mechanical filter waste outlet 67. The at least one mechanical filter 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 filter device 15 through the at least one mechanical filter inlet 61. The at least one mechanical filter inlet 61 is preferably located in a lower region of the mechanical filter device 15, and the at least one mechanical filter outlet 63 is preferably located in an upper region of the mechanical filter device 15. The mechanical filter device 15 filters the wastewater supplied from the bioreactor 13. The mechanical filter chamber 70 includes a mechanical filter medium 69 for performing mechanical filtration of the wastewater. The mechanical filter media 69 comprises a plurality of mechanical filter elements 71 of the type described herein. The mechanical filter elements 71 form a fixed-bed filter pack 75 suitable for filtering particles and matter suspended in water flowing through the mechanical filter device 15. The mechanical filter elements 71 have an open-cell structure to promote settling of suspended particles within the fixed-bed filter pack 75. The mechanical filter elements 71 each have one or more filter cells 73. The wastewater is filtered by the mechanical filter media 69 to remove at least a portion of the solid particles suspended in the wastewater provided from the bioreactor 13. The treated wastewater (effluent) is discharged from the mechanical filter device 15 through at least one mechanical filter outlet 63.

[0104] The mechanical filter device 15 is periodically cleaned to drain accumulated solids from the mechanical filter chamber 70. Cleaning the mechanical filter device 15 may include closing at least one mechanical filter inlet 61 and / or at least one mechanical filter outlet 63. The mechanical filter waste outlet 67 is closed during filtration operations and opened to purge (or drain) the mechanical filter chamber 60 during cleaning operations. An air supply conduit is provided to supply air to the mechanical filter chamber 70 through the air inlet 65. The air introduced into the mechanical filter chamber 70 agitates the mechanical filter element 71 and disrupts the fixed-bed filter pack. Agitating the mechanical filter element 71 dislodges waste and debris accumulated in one or more filter cells 73 formed in the mechanical filter element 71. The removed waste is discharged and disposed of through the mechanical filter waste outlet 67. An air pump (not shown) can pump air into the mechanical filter tank 60 to agitate the mechanical filter element 71 during cleaning operations. Alternatively, or in addition, air can be drawn into the mechanical filter chamber 70 through the air supply conduit. A one-way valve can be provided in the air supply conduit. When the mechanical filter waste outlet 67 is opened, water within the mechanical filter chamber 70 is drained, which can cause the pressure within the mechanical filter chamber 70 to drop below atmospheric pressure. This drop in pressure can draw air into the mechanical filter chamber 70 through the air supply conduit. Air is drawn into the lower portion of the mechanical filter chamber 70, agitating the mechanical filter element 71 as the mechanical filter tank 60 is drained. Other techniques can also be employed to clean the mechanical filter apparatus 15. For example, the mechanical filter element 71 can be backwashed to remove trapped debris. A backwash liquid, such as water, can be introduced into the mechanical filter chamber 70 to clean the mechanical filter element 71. The backwash liquid can be discharged as waste. Alternatively, at least a portion of the backwash liquid can be returned to the wastewater treatment plant 1 for further processing. For example, the backwash liquid can be introduced into the bioreactor 13. The same cleaning process can be used to clean the mechanical filter apparatus 15 in each embodiment of the wastewater treatment plant 1 described herein.

[0105] A portion of the wastewater discharged from the mechanical filter chamber 70 can be returned for further processing within the wastewater treatment plant 1. In this embodiment, a waste return line 83 is provided to return the wastewater discharged from the mechanical filter device 15. A waste control valve 85 can optionally be provided to control the supply of waste to the waste return line 83. In this embodiment, a portion of the waste from the mechanical filter chamber 70 is returned to the bioreactor 13. The waste returned from the mechanical filter device 15 is typically in the form of sludge (including or consisting of settled solids). The waste can be introduced into the bioreactor 13 through the bioreactor inlet 41 or another inlet. This allows at least a portion of the waste to be recirculated through the bioreactor 13 and the mechanical filter device 15. A portion of the waste discharged from the mechanical filter chamber 70 can be sent for further processing downstream of the waste or wastewater treatment plant 1.

[0106] In use, the mechanical filter elements 71 form a fixed bed filter pack 75 that operates to filter solids from wastewater. The mechanical filter elements 71 can have positive, negative, or neutral buoyancy. The mechanical filter elements 71 have an open cell structure that provides a high retention capacity. The flow rate per unit cross-sectional area of ​​the fixed bed filter pack 75 is typically 20 m 3 / m 2 / h, for example, less than 0.1 m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 / h. These flow rates per unit cross-sectional area have been recognized to be particularly effective for removing flocs (also known as aggregates) from wastewater. Flocs may include or consist of loosely agglomerated particles or soft flakes. In at least certain embodiments, the flocs may settle within or outside the filter cells 73 of the mechanical filter element 71. A relatively low flow rate through the fixed-bed filter pack 75 helps reduce or avoid floc breakup. Higher flow rates may cause some flocs to break down or disintegrate into smaller flocs or individual particles. In at least certain embodiments, the wastewater treatment plant 1 can capture very fine particles suspended in the wastewater. Treated water from the mechanical filter device 15 is discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water may be sent downstream for further treatment.

[0107] A further variant of the wastewater treatment plant 1 according to the embodiment shown in Figure 4 will now be described with reference to Figure 5. Like reference numerals are used for like components. The description will focus on the differences between the wastewater treatment plant 1 according to this embodiment and the embodiment described with reference to Figure 4.

[0108] The bioreactor 13 may be a fluidized bed bioreactor or a fixed bed bioreactor. For example, the bioreactor 13 may include a submerged aerated filter (SAF). In this embodiment, the bioreactor 13 does not include a biological filter element. The bioreactor 13 may also be an activated sludge bioreactor. Other types of bioreactors 13 are also contemplated.

[0109] The wastewater treatment plant 1 of this embodiment includes at least one tertiary settling tank 111. The tertiary settling tank 111 is located downstream of the bioreactor 13 and upstream of the mechanical filter device 15. The tertiary settling tank 111 includes at least one tertiary settling tank inlet 131 in fluid communication with the at least one bioreactor outlet 43. In use, wastewater from the bioreactor 13 is introduced into the tertiary settling tank 111. The tertiary settling tank 111 includes at least one tertiary settling tank outlet 133 and at least one tertiary settling tank waste outlet 135. As shown in FIG. 5 , the at least one tertiary settling tank inlet 131 and the at least one tertiary settling tank outlet 133 are located in an upper region of the tertiary settling tank 111. The at least one tertiary settling tank waste outlet 135 is located in a lower region of the tertiary settling tank 111. In use, water treated in the bioreactor 13 is introduced into the tertiary settler 111 through at least one tertiary settler inlet 131. Solids settle from the wastewater and sink to the bottom of the tertiary settler 111. The wastewater is discharged from the tertiary settler 111 through at least one tertiary settler outlet 133 to the mechanical filter device 15. At least one settler waste valve 137 is provided to control the discharge of solids and waste through the tertiary settler waste outlet 35. The waste discharged from the at least one settler 111 is typically in the form of sludge. The at least one settler waste valve 37 is selectively opened to discharge accumulated waste. The waste discharged from the at least one tertiary settler 111 can be sent for disposal or further processing. A portion of the waste discharged from the at least one tertiary settler 111 can be returned to the bioreactor 13 for processing. A wastewater control valve (not shown) may optionally be provided to control the discharge of wastewater from the tertiary settler 111 through at least one settler outlet 33 .

[0110] In use, the mechanical filter elements 71 form a fixed bed filter pack 75 that operates to filter solids from wastewater. The mechanical filter elements 71 can have positive, negative, or neutral buoyancy. The mechanical filter elements 71 have an open cell structure that provides a high retention capacity. The flow rate per unit cross-sectional area of ​​the fixed bed filter pack 75 is typically 20 m 3 / m 2 / h, for example, less than 0.1 m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 / h. These flow rates per unit cross-sectional area have been recognized to be particularly effective for removing flocs (also known as aggregates) from wastewater. Flocs may include or consist of loosely agglomerated particles or soft flakes. In at least certain embodiments, the flocs may settle within or outside the filter cells 73 of the mechanical filter element 71. A relatively low flow rate through the fixed-bed filter pack 75 helps reduce or avoid floc breakup. Higher flow rates may cause some flocs to break down or disintegrate into smaller flocs or individual particles. In at least certain embodiments, the wastewater treatment plant 1 can capture very fine particles suspended in the wastewater. Treated water from the mechanical filter device 15 is discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water may be sent downstream for further treatment.

[0111] A further embodiment of the wastewater treatment plant 1 will now be described with reference to Figure 6. In this embodiment, like reference numerals are used for like features. This description will focus on the differences between this embodiment of the wastewater treatment plant 1 and the previous embodiments described herein.

[0112] The wastewater treatment plant 1 of this embodiment includes an electrocoagulation unit 91. The electrocoagulation unit 91 uses electrochemical processing to remove suspended, emulsified, or dissolved contaminants from the wastewater. The electrocoagulation unit 91 applies an electric current to the wastewater, flocculating the suspended matter in the wastewater. The electrocoagulation unit 91 utilizes a flow of electrical charge to perform an electrochemical process that can remove suspended, emulsified, or dissolved contaminants from the wastewater. The electrocoagulation unit 91 generates a direct current of electrical charge in the wastewater, liberating metal ions from a sacrificial anode that flocculates the contaminants for capture within the mechanical filter device 15. The electrocoagulation unit 91 may also include one or more sacrificial electrodes (not shown) to support the electrochemical process. The electrocoagulation unit 91 operates to flocculate suspended matter in the wastewater. Particles suspended in the wastewater can aggregate or clump together to form flocs (also known as aggregates). The resulting flocs may include or consist of loosely aggregated particles or soft flakes. The electrocoagulation unit 91 is disposed downstream of the bioreactor 13. The electrocoagulation unit 91 is disposed upstream of the mechanical filter device 15. As shown in FIG. 3 , the electrocoagulation unit 91 is disposed between the bioreactor 13 and the mechanical filter device 15. The electrocoagulation unit 91 includes an electrocoagulation unit inlet 93 and an electrocoagulation unit outlet 95. The electrocoagulation unit inlet 93 is connected to at least one bioreactor outlet 43 of the bioreactor 13. Wastewater filtered by the bioreactor 13 is supplied to the electrocoagulation unit 91. The electrocoagulation unit outlet 95 is connected to at least one mechanical filter inlet 61. The wastewater treated by the electrocoagulation unit 91 is supplied to the mechanical filter device 15. In use, the electrocoagulation unit 91 operates to flocculate solid waste removed from the biological filter element in the bioreactor 13. The flocculation from the electrocoagulation unit 91 is suspended in wastewater that is introduced into the mechanical filter device 15 disposed downstream thereof.A mechanical filter device 15 of the type described herein is effective to mechanically filter the wastewater from the electrocoagulation unit 91 .

[0113] In use, the electrocoagulation unit 91 may operate to remove phosphates from wastewater. The electrocoagulation unit 91 may cause the phosphates to come out of solution (i.e., precipitate) as solid particles in the wastewater. The electrocoagulation unit 91 may cause other compounds to come out of solution (i.e., precipitate) as solid particles in the wastewater. These solid particles may be removed using, for example, ultrafiltration or reverse osmosis. However, the mechanical filter device 15 described herein has been determined to be effective in filtering solid particles generated by the operation of the electrocoagulation unit 91. The mechanical filter device 15 is located downstream of the electrocoagulation unit 91 and removes at least a portion of the solid particles by mechanical filtration. The combination of the electrocoagulation unit 91 and the mechanical filter device 15 is believed to be independently patentable. This combination finds particular application in wastewater treatment processes. However, other applications are also contemplated. The operation of the wastewater treatment plant 1 to treat wastewater is illustrated in a second flow diagram 200 shown in FIG. 7.

[0114] Wastewater to be treated is received as influent to the wastewater treatment plant 1 (block 205). The wastewater is optionally introduced into a settling tank 11 to facilitate settling of solids (block 210). The wastewater is discharged from the settling tank 11 to a bioreactor 13 (block 215). The bioreactor 13 performs biological filtration of the wastewater, and biologically filtered water is discharged from the bioreactor (block 220). Movement of the biological filter element introduces solid particles, including or consisting of flocs, into suspension in the wastewater discharged from the bioreactor 13. The wastewater is fed from the bioreactor 13 to an electrocoagulation unit 91 (block 225). The electrocoagulation unit 91 operates to flocculate the solid particles held in suspension (block 230). Alternatively, or in addition, the electrocoagulation unit 91 can cause dissolved phosphates in the wastewater to come out of solution and form particles. The phosphate particles then flocculate, and the resulting flocculated particles can be suspended in the wastewater. The treated wastewater is discharged from the electrocoagulation unit 91 (block 235). The wastewater is supplied from the electrocoagulation unit 91 to the mechanical filter device 15 (block 240). The mechanical filter device 15 mechanically filters the wastewater to remove at least a portion of the solid particles held in suspension (block 245). The treated wastewater (effluent) is discharged from the mechanical filter device 15 (block 250). The mechanical filter device 15 is periodically cleaned (block 255). Cleaning involves disrupting the fixed-bed filter pack 75 by introducing pressurized fluid, such as air, into the fixed-bed filter pack (block 260). Accumulated solid waste is removed from the fixed-bed filter pack and discharged from the mechanical filter device 15 (block 265). At least a portion of the solid waste from the mechanical filter device 15 is returned through the waste return line 83 and passed through the bioreactor 13 again (block 270). The process continues (block 275).

[0115] The wastewater treatment plant 1 has been described with reference to an electrocoagulation unit 91. Alternatively, or in addition, the wastewater treatment plant 1 may include at least one chemical injection system 97 for introducing a (chemical) coagulant into the wastewater. The chemical injection system 97 may be disposed between the bioreactor 13 and the mechanical filter device 15. The chemical injection system 97 is configured to introduce an injection amount of coagulant into the wastewater. The coagulant may 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 flocculation of particles suspended in the wastewater. The coagulant may also cause dissolved compounds, such as phosphates, to come out of solution and form particles. The flocculated particles may include loosely aggregated particles or soft flakes, or may form flocs (also known as aggregates) consisting of loosely aggregated particles or soft flakes. At least a portion of the flocs are suspended in the wastewater. In this embodiment, the coagulant is a chemical such as ferric chloride or polyaluminum sulfate (PAC). The coagulant may cause dissolved phosphates in the wastewater to come out of solution and form particles. The particles come out of solution and flocculate. A chemical injection system 97 can replace the electrocoagulation unit 91. In this configuration, the chemical injection system 97 is located downstream of the bioreactor 13 and upstream of the mechanical filter device 15. The chemical injection system 97 is located between the bioreactor 13 and the mechanical filter device 15. The chemical injection system 97 is configured to supply coagulant to the wastewater discharged from the bioreactor 13. Chemical flocculation (residence time) is a function of the amount of wastewater injected, but a residence time of 10 to 40 minutes is appropriate. The water is agitated to distribute the coagulant. The mixed water is stabilized, and at least a portion of the particles form together or flocculate and drop out of suspension (flocculation) for recovery.

[0116] The coagulant may comprise or consist of organic or inorganic chemicals or polymer-based materials. Suitable coagulants include ferric sulfate, ferric chloride, ferrous sulfate, aluminum sulfate and aluminum chloride, or polyaluminum chloride (PAM), activated silica, bentonite, and metal hydroxides with polymeric structures, natural flocculants (e.g., starch derivatives, Moringa oleracea polysaccharides, and alginates, or seaweed), and natural flocculants (e.g., polyacrylamides, polyethyleneimines, polyamines, polydiallyldimethylammonium chlorides (Poly DADMACs) and polytannates, polyamidoamines, polyamines, and polyethylene oxides). The chemical injection system 97 can be configured to introduce one or more of these coagulants into the wastewater.

[0117] Wastewater is fed from bioreactor 13 to chemical injection system 97. A coagulant is introduced into the wastewater to cause flocculation of solid particles held in suspension. In at least certain embodiments, the coagulant may cause dissolved phosphates in the wastewater to come out of solution and form particles. The phosphate particles may flocculate to form flocs suspended in the wastewater. The treated wastewater is discharged to mechanical filter device 15. Mechanical filter device 15 mechanically filters the wastewater to remove at least a portion of the solid particles and / or flocs held in suspension. The treated wastewater (effluent) is discharged from mechanical filter device 15.

[0118] In use, the fixed bed filter pack 75 formed by the mechanical filter elements 71 is effective in filtering flocs suspended in wastewater. The mechanical filter elements 71 have an open cell structure that provides a high retention capacity. In at least certain embodiments, the flow rate per unit cross-sectional area of ​​the fixed bed filter pack 75 is exclusively 20 m 3 / m 2 / h, for example, 0.1 m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 / h. These flow rates per unit cross-sectional area have been recognized to be particularly effective in removing flocs from wastewater. Flocs can settle within or outside the filter cells 73 of the mechanical filter element 71. The relatively low flow rates through the fixed-bed filter pack 75 help reduce or avoid floc breakup. Higher flow rates may cause some flocs to break down or disintegrate into smaller flocs or individual particles.

[0119] The coagulation and flocculation processes create particles that need to be captured. The mechanical filter device 15 described herein can do this effectively. In at least certain embodiments, this can be done without the need for a settling tank and / or without requiring large amounts of water to backwash or clean the filter screens. The open-cell structure of the mechanical filter element 71 is well-suited to retain soft floc within the filter cells. The mechanical filter element 71 has a high retention capacity for accumulating waste without forming a barrier (floc buildup) that water cannot penetrate.

[0120] Next, a modified example of the wastewater treatment plant 1 shown in Fig. 6 will be described with reference to Fig. 8. Similar components will be designated by similar reference numerals. The following description will focus on the differences between the wastewater treatment plant 1 according to this embodiment and the embodiment described with reference to Fig. 8.

[0121] The wastewater treatment plant 1 comprises a primary screen 9, a primary settler 11, a bioreactor 13, and a mechanical filter device 15. The wastewater treatment plant 1 may optionally comprise a tertiary settler 20. The tertiary settler 20 may be located between the bioreactor 13 and the mechanical filter device 15. The bioreactor 13, in this embodiment, comprises a fluidized bed bioreactor (MBBR). Other types of bioreactors 13 are also contemplated. It will be understood that one or more of the primary settler 11, the bioreactor 13, and the mechanical filter device 15 may comprise civil engineering facilities in the form of, for example, a concrete tank, a steel tank, or a glass fiber reinforced polymer (GFRP) tank.

[0122] The wastewater treatment plant 1 of this embodiment includes a first chemical injection system 97-1 and a second chemical injection system 97-2. The first chemical injection system 97-1 is disposed upstream of the bioreactor 13, and the second chemical injection system 97-2 is disposed downstream of the bioreactor 13. In this embodiment, the first chemical injection system 97-1 is disposed between the primary settling tank 11 and the bioreactor 13, and the second chemical injection system 97-2 is disposed between the bioreactor 13 and the mechanical filter device 15. The first and second chemical injection systems 97-1 and 97-2 are configured to introduce a coagulant into the wastewater. The coagulant may cause one or more dissolved compounds, such as phosphates, to come out of solution and form particles. Alternatively, or in addition, clumps of microorganisms on the biological filter element may be removed, introducing more particles into the wastewater. The coagulant promotes the coagulation or flocculation 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 injection systems 97-1, 97-2 with one or more electrocoagulation units 91 of the type described herein.

[0123] The mechanical filter device 15 is configured to perform mechanical filtration of wastewater discharged from the bioreactor 13 to remove at least a portion of solid particles suspended in the wastewater. The mechanical filter device 15 includes a mechanical filter chamber 60, at least one mechanical filter inlet 61, at least one mechanical filter outlet 63, at least one mechanical filter air inlet 65, and at least one mechanical filter waste outlet 67. The at least one mechanical filter 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 filter device 15 through the at least one mechanical filter inlet 61. The at least one mechanical filter inlet 61 is preferably located in a lower region of the mechanical filter device 15, and the at least one mechanical filter outlet 63 is preferably located in an upper region of the mechanical filter device 15. The mechanical filter device 15 filters the wastewater supplied from the bioreactor 13. The mechanical filter chamber 70 includes a mechanical filter medium 69 for performing mechanical filtration of the wastewater. The mechanical filter media 69 comprises a plurality of mechanical filter elements 71 of the type described herein. The mechanical filter elements 71 form a fixed-bed filter pack 75 suitable for filtering particles and materials suspended in water as the water flows through the mechanical filter device 15. The mechanical filter elements 71 have an open-cell structure to promote settling of suspended particles within the fixed-bed filter pack 75. The mechanical filter elements 71 each have one or more filter cells 73. The wastewater is filtered by the mechanical filter media 69 to remove at least a portion of the solid particles suspended in the wastewater provided from the bioreactor 13. The treated wastewater (effluent) exits the mechanical filter device 15 through at least one mechanical filter outlet 63.

[0124] The mechanical filter device 15 is periodically cleaned to remove accumulated solids from the mechanical filter chamber 70. Cleaning of the mechanical filter device 15 is accomplished using methods described herein. A portion of the wastewater discharged from the mechanical filter chamber 70 may be returned for further processing within the wastewater treatment plant 1. In this embodiment, a waste return line 83 is provided to return the wastewater discharged from the mechanical filter device 15.

[0125] A waste control valve 85 can optionally be provided to control the supply of waste to the waste return line 83. In this embodiment, a portion of the waste from the mechanical filter chamber 70 is returned to the bioreactor 13. The waste returned from the mechanical filter device 15 is typically in the form of sludge (which may include or consist of settled solids). The waste can be introduced into the bioreactor 13 through the bioreactor inlet 41 or another inlet. A portion of the waste discharged from the mechanical filter chamber 70 can be sent for further processing downstream to the waste or wastewater treatment plant 1. In use, the mechanical filter element 71 forms a fixed-bed filter pack 75 that operates to filter solids from the wastewater. The mechanical filter element 71 can have positive, negative, or neutral buoyancy. The mechanical filter element 71 has an open-cell structure that provides a high retention capacity. The flow rate per unit cross-sectional area of ​​the fixed-bed filter pack 75 is exclusively 20 m 3 / m 2 / h, for example, less than 0.1 m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 / h. These flow rates per unit cross-sectional area have been recognized to be particularly effective for removing flocs (also known as aggregates) from wastewater. Flocs include or consist of loosely agglomerated particles or soft flakes. In at least certain embodiments, flocs can settle within or outside the filter cells 73 of the mechanical filter element 71. A relatively low flow rate through the fixed-bed filter pack 75 helps reduce or avoid floc breakup. Higher flow rates may cause some flocs to break down or disintegrate into smaller flocs or individual particles. Treated water from the mechanical filter device 15 is discharged from the wastewater treatment plant 1 or sent to a receiving waterway. Alternatively, the treated water may be sent downstream for further treatment.

[0126] Next, a modified example of the wastewater treatment plant 1 shown in Fig. 8 will be described with reference to Fig. 9. Similar components are designated by similar reference numerals. The following description will focus on the differences between the wastewater treatment plant 1 according to this embodiment and the embodiment described with reference to Fig. 9.

[0127] The wastewater treatment plant 1 comprises a primary screen 9, a primary settler 11, a bioreactor 13, and a mechanical filter device 15. The wastewater treatment plant 1 can optionally comprise a tertiary settler 20. The tertiary settler 20 can be located between the bioreactor 13 and the mechanical filter device 15. The bioreactor 13, in this embodiment, comprises a fluidized bed bioreactor (MBBR). Other types of bioreactors 13 are also contemplated. For example, the bioreactor 13 may comprise a submerged aerated filter (SAF) of the type described herein.

[0128] The wastewater treatment plant 1 includes a first chemical injection system 97-1, a second chemical injection system 97-2, and a third chemical injection system 97. The first chemical injection system 97-1 is disposed upstream of the bioreactor 13. In this embodiment, the first chemical injection system 97-1 is disposed between the primary settling tank 11 and the bioreactor 13. The second and third chemical injection systems 97-2 and 97-3 are disposed downstream of the bioreactor 13. The second chemical injection system 97-2 is disposed between the bioreactor 13 and the tertiary settling tank 20. The third chemical injection system 97-3 is disposed between the tertiary settling tank 20 and the mechanical filter device 15. Each of the first, second, and third chemical injection systems 97-1, 97-2, and 97-3 is configured to introduce a coagulant into the wastewater. The coagulant can cause one or more dissolved compounds, such as phosphates, to come out of solution and form particles. The coagulant promotes the aggregation or clumping of particles suspended in the wastewater. The coagulant can promote the aggregation 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, second, and third chemical injection systems 97-1, 97-2, 97-3 with one or more electrocoagulation units 91 of the type described herein.

[0129] The operation of the wastewater treatment plant 1 according to this embodiment is consistent with other embodiments described herein. The mechanical filter device 15 operates to filter particulates and flocs from the wastewater. The flow rate per unit cross-sectional area of ​​the fixed bed filter pack 75 is 20 m 3 / m 2 Exclusively less than / h, e.g. 0.1m 3 / m 2 / h~19.9m 3 / m 2 / h, 5m 3 / m 2 / h~19.5m 3 / m 2 / h, or 11m 3 / m 2 / h~19m 3 / m 2 / h. The mechanical filter media 69 can be positively, neutrally, or negatively buoyant. In this embodiment, the mechanical filter media 69 is positively buoyant.

[0130] The wastewater treatment plant 1 described herein may be a wastewater treatment plant 1. The wastewater to be treated is in the form of sewage. The wastewater treatment plant 1 described herein may be a municipal wastewater treatment plant 1 for treating municipal sewage. The wastewater treatment plant 1 may, for example, be capable of treating 1.2 million liters of wastewater per day. To remain in compliance with regulations, the wastewater treatment plant 1 must be able to treat the wastewater to meet a discharge permit. Discharge permits typically include limits on contaminants, including biochemical oxygen demand (BOD), total suspended solids (TSS), phosphate (P), nitrate (N), and ammonia in the form of ammoniacal nitrogen (NH3 / N). Discharge permits are set by water utilities when water is received for treatment and by regulations when water is discharged into the environment. Removal of macronutrients, such as phosphate and nitrate, is particularly important because these nutrients have a negative impact on receiving waterways.

[0131] As described herein, the flow rate per unit cross-sectional area of ​​the mechanical filter media 69 affects the filtration of wastewater. The retention capacity of the mechanical filter device 15 depends on the volume of the mechanical filter media 69 within the mechanical filter tank 60. To facilitate cleaning of the mechanical filter media 69, the filter media 69 preferably occupies approximately 40% to 60% of the volume of the mechanical filter chamber 70. In a preferred embodiment, the filter media 69 occupies approximately 50% of the volume of the mechanical filter chamber 70.

[0132] The mechanical filter device 15 may include mechanical filter tanks 60 of different sizes. The mechanical filter tanks 60 may include or consist of a cylindrical section with a circular cross-section. The mechanical filter tanks 60 may have different cross-sections, such as polygonal, rectangular, or square. The mechanical filter tanks 60 may be oriented so that their central longitudinal axis extends vertically or horizontally. The mechanical filter chamber 70 formed in the mechanical filter tank 60 has a height (h) and a width (w). For a mechanical filter tank 60 having or consisting of a cylindrical section, the width (w) corresponds to the diameter of the cylindrical section, and the height (h) corresponds to the height of the cylindrical section (i.e., excluding any tapered or curved ends). The ratio of the height (h) to the width (w) of the mechanical filter tank 60 is preferably in the range of 1.5 to 2. The ratio of the height (h) to the width (w) of the mechanical filter tank 60 is preferably in the range of 1.75 to 2. Mechanical filter vessels 60 having this height (h) to width (w) ratio have been determined to be particularly effective when the mechanical filter media 69 occupies between 40% and 60% of the volume of the mechanical filter chamber 70. Particularly preferred are mechanical filter vessels 60 having a height (h) equal to about twice the width (w) and containing 50% by volume of filter media 69. The filter pack formed within the mechanical filter chamber 70 by the mechanical filter media 69 preferably has a depth approximately equal to the width (w) of the mechanical filter vessel 60.

[0133] 10A shows a first mechanical filter tank 60A as an example. The first mechanical filter tank 60 has a cylindrical portion. The first mechanical filter tank 60 has a mechanical filter inlet 61, a mechanical filter outlet 63, and a mechanical filter waste outlet 67. The cylindrical portion of the first mechanical filter tank 60A has a diameter of 1.2 m.

[0134] A second mechanical filter tank 60B is shown in Figure 10B as an example. The second mechanical filter tank 60 has a cylindrical portion. The second mechanical filter tank 60B has a mechanical filter inlet 61, a mechanical filter outlet 63, and a mechanical filter waste outlet 67. The cylindrical portion of the first mechanical filter tank 60B has a diameter of 0.9 m.

[0135] A third mechanical filter tank 60C is shown in Figure 10C as an example. The third mechanical filter tank 60 has a cylindrical portion. The third mechanical filter tank 60C includes a mechanical filter inlet 61, a mechanical filter outlet 63, and a mechanical filter waste outlet 67. The cylindrical portion of the third mechanical filter tank 60C has a diameter of 0.75 m.

[0136] A fourth mechanical filter vessel 60D is shown in FIG. 10D as an example. The fourth mechanical filter vessel 60D has a cylindrical portion. The fourth mechanical filter vessel 60D includes a mechanical filter inlet 61, a mechanical filter outlet 63, and a mechanical filter waste outlet 67. The cylindrical portion of the fourth mechanical filter vessel 60D has a diameter of 0.6 m.

[0137] A fifth mechanical filter tank 60E is shown in Figure 10E as an example. The fourth mechanical filter tank 60 has a cylindrical portion. The fourth mechanical filter tank 60E includes a mechanical filter inlet 61, a mechanical filter outlet 63, and a mechanical filter waste outlet 67. The cylindrical portion of the fourth mechanical filter tank 60E has a diameter of 0.5 m.

[0138] The mechanical filter device 15 is sized according to the flow rate of the wastewater being treated. The wastewater treatment plant 1 may be a wastewater treatment plant configured to treat sewage. Sewage is typically defined in terms of population equivalents (PE), which represent the amount of wastewater per person (usually defined as 150-180 liters per day). The treated water from the wastewater treatment plant 1 must meet certain standards (defined in the UK by BSEN 12566-3). The standards may define one or more thresholds for biochemical oxygen demand (BOD), suspended solids (SS), and ammonia (NH4-N) content. The BOD threshold may be defined as 20 mg / L (BOD 20 mg / L). The suspended solids threshold may be defined as less than 30 mg / L (SS < 30 mg / L). The ammonia threshold may be defined as less than 20 mg / L. There may also be requirements for other contaminants, such as nitrates and phosphates.

[0139] The operating parameters of the package (sewage) installation are summarized in Table A below. The wastewater treatment plant 1 comprises at least one mechanical filter device 15 of the type described herein for mechanical filtration of the wastewater discharged from the bioreactor 13. The number and size (diameter φ) of the mechanical filter devices 15 in the wastewater treatment plant 1 are summarized in the table. In this example, the wastewater treatment plant 1 comprises a single mechanical filter device 15 having a diameter of 0.6 m.

[0140] [Table 1]

[0141] The operating parameters of various small-scale (sewage) installations are summarized below in Table B. The wastewater treatment plant 1 comprises at least one mechanical filter device 15 of the type described herein for mechanical filtration of the wastewater discharged from the bioreactor 13. The number and size (diameter φ) of the mechanical filter devices 15 in the wastewater treatment plant 1 are summarized in the table.

[0142] [Table 2]

[0143] The operating parameters of a large (sewage) plant are summarized below in Table C. The wastewater treatment plant 1 comprises at least one mechanical filter device 15 of the type described herein for mechanical filtration of the wastewater discharged from the bioreactor 13. The number and size (diameter φ) of the mechanical filter devices 15 in the wastewater treatment plant 1 are summarized in the table. In this example, the wastewater treatment plant 1 comprises a single mechanical filter device 15 with a diameter of 0.6 m.

[0144] [Table 3]

[0145] It will be understood that various changes and modifications can be made to the present invention without departing from the scope of the application. Further aspects of the invention are described in the following numbered appendices: Appendix 1. A wastewater treatment method for treating wastewater, comprising: receiving wastewater for treatment; supplying the wastewater to a bioreactor equipped with a biological filter medium for biologically filtering the wastewater, the biological filter medium being for biologically filtering the wastewater, the biological filter medium comprising a plurality of biological filter elements for supporting colonies of microorganisms on the surface of the wastewater, the biological filter elements circulating within the bioreactor during filtration, and the circulation of the biological filter elements causing solid waste to be detached from the biological filter elements and suspended in the wastewater; feeding wastewater discharged from the bioreactor to a mechanical filter device located downstream of the bioreactor, the mechanical filter device comprising a fixed-bed filter pack for filtering solid waste that has detached from a biological filter element in the bioreactor and is suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and discharging the treated wastewater. Appendix 2. Supplying the wastewater to a settling tank located upstream of the bioreactor to settle solids; and feeding the wastewater from the settling tank to a bioreactor. Appendix 3. The wastewater treatment method of Appendix 1 or 2, comprising introducing pressurized air into the bioreactor to circulate the biological filter media in the bioreactor. Clause 4. The wastewater treatment method of any one of the preceding clauses, comprising periodically cleaning the mechanical filter device to remove solid waste accumulated within the fixed bed filter pack, wherein cleaning the mechanical filter device involves breaking down the fixed bed filter pack to remove solid waste accumulated within the mechanical filter element. Appendix 5. The wastewater treatment method of Appendix 4, wherein the fixed-bed filter pack is destroyed after closing at least one of an inlet of the mechanical filter device that receives wastewater from the bioreactor and an outlet of the mechanical filter device that discharges treated wastewater from the mechanical filter device. Appendix 6. The wastewater treatment method of Appendix 4 or 5, wherein air is introduced into the mechanical filter device at a pressure greater than atmospheric pressure to disrupt the fixed bed filter pack. Clause 7. The wastewater treatment method of any of Clauses 4, 5, or 6, including the step of opening a wastewater outlet of the mechanical filter device to discharge at least a portion of the wastewater within the mechanical filter device along with any solid waste removed from the mechanical filter element. Clause 8. The method of any of clauses 4 to 7, wherein at least a portion of the solid waste removed from the mechanical filter element is reintroduced upstream of the bioreactor for further biological filtration. Clause 9. The wastewater treatment method of clause 8, wherein the solid waste removed from the mechanical filter element is introduced directly into a bioreactor. Schedule 10. A wastewater treatment method according to Schedule 8, depending directly or indirectly from Schedule 2, wherein the solid waste removed from the mechanical filter element is introduced into a settling tank. Clause 11. The wastewater treatment method of any preceding clause, wherein an electrocoagulation unit is used to flocculate material suspended in the wastewater. Appendix 12. The wastewater treatment method of Appendix 11, wherein the electrocoagulation unit is positioned upstream of the mechanical filter device, and the flocculants are suspended in the wastewater that is introduced into the mechanical filter device. Clause 13. The wastewater treatment method of clause 11 or 12, wherein an electrocoagulation unit is positioned downstream of the bioreactor to flocculate solid waste removed from the biological filter element in the bioreactor. Appendix 14. A wastewater treatment method for treating wastewater, comprising: receiving wastewater to be treated; feeding the wastewater to a bioreactor equipped with a biological filter medium for biological filtration of the wastewater; a biological filter medium for biologically filtering wastewater, the biological filter medium comprising a plurality of biological filter elements for supporting colonies of microorganisms on the surface of the wastewater, the biological filter elements circulating in the bioreactor during filtration, and the circulation of the biological filter elements removing solid waste from the biological filter elements and suspending them in the wastewater; feeding the wastewater discharged from the bioreactor to an electrostatic flocculation unit to flocculate solid waste removed from the biological filter element in the bioreactor; and discharging the treated wastewater. Appendix 15. A wastewater treatment method for treating wastewater, comprising: receiving wastewater for treatment; feeding the wastewater to an electrocoagulation unit to flocculate suspended solids in the wastewater; supplying wastewater from the electrocoagulation unit to a mechanical filter device, the mechanical filter device comprising a fixed bed filter pack for filtering flocculated solids from the electrocoagulation unit, the fixed bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and discharging the treated wastewater. Appendix 16. A wastewater treatment plant for treating wastewater, an inlet for receiving wastewater for treatment; a bioreactor for biologically filtering wastewater, the bioreactor comprising a biological filter medium suitable for supporting a colony of microorganisms, the bioreactor comprising means for circulating the biological filter medium within the bioreactor during filtration; a mechanical filter device disposed downstream of the bioreactor, the mechanical filter device comprising a fixed-bed filter pack for filtering solid waste dislodged from the biological filter element in the bioreactor and suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and an outlet for discharging the treated wastewater. Appendix 17. The wastewater treatment plant of Appendix 16, further comprising a settling tank for promoting settling of solids suspended in the wastewater, the settling tank being located upstream of the bioreactor. Appendix 18. The wastewater treatment plant of Appendix 16 or 17, comprising a pressurized air supply for introducing pressurized air into the bioreactor to circulate the biological filter media in the bioreactor. Clause 19. The wastewater treatment plant of any one of clauses 16, 17 or 18, comprising means for breaking fixed bed filter packs within the mechanical filter device to remove solid waste accumulated within the mechanical filter elements. Clause 20. The wastewater treatment plant of clause 19, comprising one or more valves for closing at least one of the inlet to the mechanical filter device and the outlet to the mechanical filter device while the fixed bed filter pack is being destroyed. Clause 21. The wastewater treatment plant of clause 19 or clause 20, comprising a pressurized air supply for introducing air into the mechanical filter device to disrupt the fixed bed filter pack. Clause 22. The wastewater treatment plant of any one of clauses 19, 20 or 21, comprising a wastewater outlet of the mechanical filter device operable to discharge at least a portion of the wastewater within the mechanical filter device. Clause 23. The wastewater treatment plant of clause 22, comprising a return line configured to return at least a portion of the wastewater from the mechanical filter device for reintroduction into the wastewater treatment plant upstream of the bioreactor. Clause 24. The wastewater treatment plant of clause 23, wherein a return line is connected to the bioreactor and returns the wastewater from the mechanical filter device to the bioreactor. Schedule 25. A wastewater treatment plant as set forth in Schedule 23, dependent directly or indirectly on Schedule 17, in which the return line is connected to the settling tank and returns the wastewater from the mechanical filter device to the settling tank. Appendix 26. A wastewater treatment plant according to any one of appendices 16 to 25, comprising an electrocoagulation unit for flocculating material suspended in the wastewater. Appendix 27. A wastewater treatment plant according to Appendix 26, wherein the electrocoagulation unit is located upstream of the mechanical filter device, and in use, the flocculants are suspended in the wastewater introduced into the mechanical filter device. Appendix 28. A wastewater treatment plant as described in Appendix 26 or 27, wherein an electrocoagulation unit is located downstream of the bioreactor and operates to flocculate solid waste suspended in the wastewater discharged from the bioreactor in use. Appendix 29. A wastewater treatment plant for treating wastewater, an inlet for receiving wastewater for treatment; a bioreactor for biologically filtering wastewater, the bioreactor comprising a biological filter medium suitable for supporting a colony of microorganisms, the bioreactor comprising means for circulating the biological filter medium within the bioreactor during filtration; an electrocoagulation unit disposed downstream of the bioreactor and configured to flocculate suspended matter in the wastewater discharged from the bioreactor; Equipped with. Appendix 30. A wastewater treatment plant for treating wastewater, comprising: an inlet for receiving wastewater to be treated; an electrocoagulation unit for flocculating suspended solids in the wastewater; a mechanical filter device disposed downstream of the electrocoagulation unit, the mechanical filter device comprising a fixed-bed filter pack for filtering flocculated solids discharged from the electrocoagulation unit and suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and an outlet for discharging the treated wastewater. First Flowchart Label 105 Influent wastewater is received 110 (Optional) Pass wastewater through a settling tank 115 Wastewater introduced into bioreactor 120 Biological filtration of wastewater takes place in a bioreactor 125 Water is introduced into a mechanical filter device 130 Mechanical filtration of wastewater using a mechanical filter element with one or more open filter cells 135 Discharge treated water (wastewater) 140 Regularly clean mechanical filter devices 145 Destroy the filter pack 150 Eliminate accumulated waste 155 Recirculating at least a portion of the discharged water through the bioreactor. 160 Continue the process Second Flowchart Label 205 Influent wastewater is received 210 (Optional) Pass wastewater through a settling tank 215 Wastewater introduced into the bioreactor 220 Biological filtration of wastewater takes place in a bioreactor 225 Water is introduced into the electrocoagulation unit 230 Electrocoagulation unit aggregates particles 235 Discharge treated water from the electrocoagulation unit 240 Water is introduced into a mechanical filter device 245 Mechanical filtration of wastewater using a mechanical filter element with one or more open filter cells 250 Discharge treated water (wastewater) 255 Regularly clean mechanical filter devices 260 Destroy the filter pack 265 Dispose of accumulated waste 270 Recirculating at least a portion of the discharged water through the bioreactor. 275 Continue the process

Claims

1. A wastewater treatment method for treating wastewater, comprising: receiving wastewater for treatment; feeding the wastewater to a bioreactor to perform biological filtration of the wastewater; supplying the wastewater discharged from the bioreactor to a mechanical filter device located downstream of the bioreactor, the mechanical filter device comprising a fixed-bed filter pack for filtering solid waste suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements each having one or more filter cells; and discharging the treated wastewater.

2. 2. The wastewater treatment method of claim 1, wherein the bioreactor comprises a biological filter medium for biologically filtering the wastewater, the biological filter medium comprising a plurality of biological filter elements for supporting colonies of microorganisms on the surface of the biological filter medium, thereby performing biological filtering of the wastewater, and the fixed-bed filter pack in the mechanical filter device is removed from the biological filter elements in the bioreactor to filter solid waste suspended in the wastewater discharged from the bioreactor.

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

4. feeding the wastewater to a first settling tank located upstream of the bioreactor for settling of solids; and supplying wastewater from the first settling tank to the bioreactor. The wastewater treatment method according to any one of claims 1 to 3.

5. 5. The method of claim 4, wherein at least a portion of the solid waste accumulated in the mechanical filter device is reintroduced into the first settling tank.

6. feeding wastewater from the bioreactor to a second settling tank located downstream of the bioreactor for settling solids; and feeding the wastewater from the settling tank to the mechanical filter device.

7. 7. The method of claim 1, further comprising introducing pressurized air into the bioreactor to circulate the biological filter media within the bioreactor.

8. 8. The wastewater treatment method of claim 1, further comprising periodically cleaning the mechanical filter device to remove solid waste accumulated within the fixed bed filter pack, wherein cleaning the mechanical filter device comprises breaking down the fixed bed filter pack to remove solid waste accumulated within the mechanical filter element.

9. 9. The wastewater treatment method according to claim 8, wherein the fixed-bed filter pack is destroyed after closing at least one of an inlet of the mechanical filter device that receives wastewater from the bioreactor and an outlet of the mechanical filter device that discharges treated wastewater from the mechanical filter device.

10. 10. The method of claim 8 or 9, wherein pressurized fluid is introduced into the mechanical filter device to disrupt the fixed bed filter pack.

11. 11. The wastewater treatment method of claim 8, 9, or 10, further comprising opening a wastewater outlet of the mechanical filter device to discharge at least a portion of the wastewater within the mechanical filter device along with the solid waste removed from the mechanical filter element.

12. 5. The method of claim 1, further comprising reintroducing at least a portion of the solid waste accumulated in the mechanical filter device into the bioreactor or upstream of the bioreactor for further biological filtration.

13. 11. A method for treating wastewater according to any one of claims 1 to 10, wherein an electrocoagulation unit is used to flocculate material suspended in the wastewater.

14. 14. The wastewater treatment method of claim 13, wherein the electrocoagulation unit is located upstream of the mechanical filter device, and the flocculants are suspended in the wastewater introduced into the mechanical filter device.

15. 15. The wastewater treatment method of claim 13 or 14, wherein the electrocoagulation unit is positioned downstream of the bioreactor to flocculate solid waste removed from the biological filter element in the bioreactor.

16. 7. A method for treating wastewater according to any one of claims 1 to 6, comprising introducing a coagulant into the wastewater upstream of the mechanical filter device.

17. 17. The wastewater treatment method of claim 16, wherein the coagulant causes dissolved phosphates in the wastewater to precipitate out of solution to form particles, and the fixed bed filter pack of the mechanical filter device filters the particles formed by the coagulant.

18. 18. The wastewater treatment method of claim 17, wherein the coagulant causes particles containing or consisting of phosphate to aggregate to form flocs, and the fixed bed filter pack of the mechanical filter device filters the flocs from the wastewater.

19. The flow rate per unit cross-sectional area of ​​the fixed bed filter pack formed in the mechanical filter device is 0.1 m ３ / m ２ / h~19m ３ / m ２ The wastewater treatment method according to any one of claims 1 to 4, wherein the total amount of the wastewater is in the range of / h.

20. A wastewater treatment plant for treating wastewater, comprising: an inlet for receiving wastewater to be treated; a bioreactor equipped with a biological filter medium for biologically filtering wastewater; a mechanical filter device located downstream of the bioreactor, the mechanical filter device comprising a fixed-bed filter pack for filtering solid waste suspended in the wastewater, the fixed-bed filter pack comprising a plurality of mechanical filter elements, each having one or more filter cells; and an outlet for discharging treated wastewater.

21. 21. The wastewater treatment plant of claim 20, wherein the bioreactor comprises the biological filter medium for biological filtration of wastewater, the biological filter medium comprising a plurality of biological filter elements for supporting colonies of microorganisms on the surface of the biological filter medium, thereby performing biological filtration of the wastewater, and the fixed bed filter pack is removed from the biological filter elements in the bioreactor to filter solid waste suspended in the wastewater discharged from the bioreactor.

22. 22. The wastewater treatment plant of claim 21, further comprising means for circulating the biological filter element within the bioreactor during filtration, wherein, in use, circulation of the biological filter element removes solid waste from the biological filter element and causes it to become suspended in wastewater discharged from the bioreactor.

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

24. 24. A wastewater treatment plant according to any one of claims 20 to 23, comprising a first settling tank for promoting settling of solids suspended in the wastewater, said first settling tank being located upstream of said bioreactor.

25. 25. The wastewater treatment plant of any one of claims 20 to 24, further comprising a second settling tank for promoting settling of solids suspended in the wastewater, said second settling tank being located between said bioreactor and said mechanical filter device.

26. means for breaking down the fixed-bed filter packs in the mechanical filter device to remove solid waste accumulated within the mechanical filter elements; The destruction means is a pump for introducing pressurized air into the fixed bed filter pack; a pump for introducing pressurized liquid into the fixed bed filter pack; a mechanical agitator for agitating the mechanical filter element; one or more air inlets for drawing air into the mechanical filter device; 26. A wastewater treatment plant according to any one of claims 20 to 25.

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

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

29. 29. The wastewater treatment plant of claim 28, depending directly or indirectly from claim 24, wherein the return line is connected to a first settling tank and returns at least a portion of the solid waste accumulated in the mechanical filter device to the first settling tank.

30. 30. A wastewater treatment plant according to any one of claims 20 to 29, comprising at least one electrocoagulation unit for flocculating material suspended in the wastewater.

31. 31. The wastewater treatment plant of claim 30, wherein the at least one electrocoagulation unit is located upstream of the mechanical filter device, and in use, flocculants are suspended in wastewater introduced into the mechanical filter device.

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

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

34. 34. The wastewater treatment process of claim 33, wherein in use, the coagulant causes dissolved phosphates in the wastewater to precipitate out of solution to form particles, and the fixed bed filter pack of the mechanical filter device is configured to filter particles comprising or consisting of phosphates.

35. 35. The wastewater treatment process of claim 34, wherein in use, particles comprising or consisting of phosphate aggregates form flocs and the fixed bed filter pack of the mechanical filter device is configured to filter the flocs from the wastewater.

36. and at least one pump for pumping wastewater into the mechanical filter device, the at least one pump being configured to provide a flow rate per unit cross-sectional area of ​​the fixed bed filter pack formed in the mechanical filter device of 0.1 m. ３ / m ２ / h to 19m ３ / m ２ 36. The wastewater treatment process of any one of claims 20 to 35, configured to achieve a treatment rate in the range of 1000 / h.

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