Water treatment

Abstract

This document provides a method for disinfecting water containing at least one microorganism and phosphorus in the form of inorganic phosphate and / or organic phosphorus, the method comprising: (i) treating the water to reduce the phosphorus concentration to 0.7 mg / L or lower; and (ii) contacting the water treated in (ii) with an amount of percarboxylic acid to provide disinfection. This document also provides a method for disinfecting water containing at least one microorganism and phosphorus in the form of inorganic phosphate and / or organic phosphorus, the method comprising contacting the water with an amount of percarboxylic acid to provide disinfection, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water and optionally also based on the concentration of total suspended solids in the water. This document also provides apparatus and systems associated with the methods, and uses of phosphorus precipitants and / or coagulants for reducing the amount of percarboxylic acid required to disinfect water containing at least one microorganism.

Description

Technical Field

[0001] This disclosure generally relates to a method for treating water. This disclosure particularly, but not exclusively, relates to disinfection methods, apparatus, and systems for optimizing the disinfection performance of percarboxylic acids in water treatment processes. The invention also relates to the use of phosphate precipitants and / or coagulants for improving the disinfection performance of percarboxylic acids in water treatment processes. Background Technology

[0002] The demand for purified water is rapidly increasing worldwide. Efforts are underway to purify water using lower concentrations of chemical disinfectants without significantly increasing the cost of purification processes. Furthermore, there is a need for biodegradable or otherwise less harmful chemicals with fewer adverse health effects.

[0003] Chlorine-based disinfectants (such as hypochlorite, chlorine dioxide, and chloramine) have traditionally been used to disinfect water, including wastewater. Chlorine-based disinfectants are highly effective against bacteria, but less effective against viruses, bacterial spores, and protozoan cysts. Furthermore, chlorine-based disinfectants produce potentially toxic and mutagenic byproducts, making them less than satisfactory for disinfection purposes.

[0004] Therefore, alternative disinfection methods were considered. Among these, ultraviolet (UV) irradiation is currently the most widely used alternative. It is typically effective against intestinal bacteria, viruses, parasite cysts, and bacterial spores without producing harmful byproducts. However, if the UV dose is too low, photoreactivation can occur, leading to potential regrowth under favorable conditions. Furthermore, UV disinfection systems are highly dependent on upstream conventional treatment processes: UV is only effective when the treated water quality is high (i.e., low turbidity) because suspended solids can protect microorganisms from UV light. In addition, UV disinfection methods are relatively energy-intensive and expensive.

[0005] Other alternative sterilization methods, such as ozonation, ultrasound, and membrane filtration, were investigated. However, these methods are generally more expensive and have their own drawbacks.

[0006] Recently, organic peroxides peracetic acid and performic acid have been considered as alternative disinfectants.

[0007] Peracetic acid (PAA or CH3COOOH) is a broad-spectrum disinfectant with a high redox potential. PAA is commercially available in the form of an acidic quaternary equilibrium mixture with acetic acid, hydrogen peroxide (H2O2), and water, as shown in the following reaction (1):

[0008]

[0009] PAA is active against a wide variety of microorganisms. The disinfection mechanism of PAA is based on the release of highly reactive oxygen species (ROS), such as hydroxyl radicals (HO·), alkoxy radicals (RO·), hydroperoxide radicals (HO2·), and superoxide radicals (O2·). - ROS can alter the metabolism of microorganisms and damage the structure of microbial cells due to chain reactions between ROS and biomolecules such as enzymes, lipids, structural proteins, and DNA. Advantageously, PAA produces little or no toxic / mutagenic byproducts upon reaction with organic matter and degrades into acetic acid, hydrogen peroxide, and water.

[0010] Formic acid (PFA or HCOOOH) has been used to disinfect effluents from primary and secondary wastewater treatment plants (see the description of wastewater treatment processes below). PFA is typically applied as a balanced mixture of PFA, water, hydrogen peroxide, and formic acid, as shown in the following reaction (2):

[0011]

[0012] PFAs are highly unstable and typically need to be generated on-site just before use. The sterilization mechanism of PFAs is considered similar to that of PAAs via ROS generation. PFAs are considered more effective than PAAs in sterilization (e.g., requiring lower doses and / or shorter contact times) to neutralize at least some microorganisms, including E. coli. E. coli ) and Enterococcus ( Enterococcus PFA is inactivated. This can be attributed to the higher redox potential of PFA, which provides a greater ability to oxidize pollutants. Similar to PAA, PFA produces little or no toxic / mutagenic byproducts after reacting with organic matter. PFA is completely biodegradable, and the degradation products of PFA include carbon dioxide and water (Gehr et al., 2009, Water Sci. Tech. 59, 89-96).

[0013] There is still a need to improve the disinfection performance of organic peroxides such as PAA and PFA in order to improve the overall efficiency of water treatment systems and reduce operating costs. Summary of the Invention

[0014] Therefore, in a first aspect, the present invention provides a method for disinfecting water, said water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, the method comprising:

[0015] (i) Treating water to reduce phosphorus concentration to 0.7 mg / L or less; and

[0016] (ii) Contact the water treated in (i) with a certain amount of percarboxylic acid to provide disinfection.

[0017] In a second aspect, the present invention provides a method for disinfecting water, the water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, the method comprising contacting the water with a certain amount of percarboxylic acid to provide disinfection, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water, and optionally also based on the concentration of total suspended solids in the water.

[0018] In a third aspect, the present invention provides an apparatus comprising:

[0019] At least one processor; and

[0020] At least one memory including computer program code, the at least one memory and the computer program code being configured together with the at least one processor to cause the device to perform the method of the present invention.

[0021] In a fourth aspect, the present invention provides a water treatment system comprising the device of the present invention, the system comprising:

[0022] The first quantitative feeding device is formulated to feed a reagent into water as a precipitant and / or coagulant to form phosphorus precipitates and / or coagulates.

[0023] The second quantitative feeding device is configured to feed percarboxylic acid into the water, and

[0024] A first measuring device is configured to measure the concentration of phosphorus in water and generate output data related to the measured phosphorus concentration.

[0025] The device is configured and arranged to receive output data related to the measured phosphorus concentration from the first measuring device, monitor the measured phosphorus concentration in the water, and adjust the amount of reagent fed into the water by the first quantitative feeding device and / or adjust the amount of percarboxylic acid fed into the water by the second quantitative feeding device based on the measured phosphorus concentration.

[0026] In a fifth aspect, the present invention provides the use of precipitants and / or coagulants for reducing the amount of percarboxylic acid required to disinfect water containing at least one microorganism, wherein the water also contains a certain concentration of phosphorus in the form of inorganic phosphate and / or organic phosphorus, wherein the use includes reducing the concentration of phosphorus in the water by contacting the water with the precipitant and / or coagulant to precipitate and / or coagulate the phosphorus and separating the precipitate and / or coagulate from the water.

[0027] Preferred features of all aspects of the invention are defined in the dependent claims.

[0028] The methods, apparatus, systems, and applications defined herein are particularly useful in wastewater treatment. The inventors have discovered that the amount of phosphorus (present as inorganic phosphates and / or organic phosphorus) and total suspended solids in the water to be treated affects the amount of percarboxylic acid required to achieve the desired level of disinfection. Specifically, water containing higher levels of these components requires more percarboxylic acid to achieve adequate disinfection.

[0029] Therefore, in water treatment processes, the amount of percarboxylic acid used in the disinfection step can be controlled based on the concentration of phosphorus and / or phosphate in the water, and optionally also on the concentration of total suspended solids. Alternatively or additionally, steps can be taken to reduce the concentration of phosphorus (in the form of inorganic phosphate and / or organic phosphorus) and optionally the concentration of total suspended solids in the water prior to disinfection, in order to improve the efficiency of the percarboxylic acid treatment step. This reduction advantageously improves the disinfection capacity of the percarboxylic acid. This, in turn, makes it possible to achieve satisfactory disinfection and meet microbial reduction targets using lower concentrations of percarboxylic acid, resulting in reduced operating costs. Attached Figure Description

[0030] To aid in understanding this disclosure and to show how to implement the embodiments, reference is made to the accompanying drawings by way of example only, wherein:

[0031] Figure 1 This is a graph showing the amount of PFA (in mg / L) required to achieve effective disinfection in wastewater samples with different total suspended solids (TSS) concentrations (in mg / L).

[0032] Figure 2 This is a graph showing the amount of PFA (in mg / L) required to achieve effective disinfection in wastewater containing different phosphorus concentrations (in mg / L) (present in the form of inorganic phosphate and organic phosphorus in the sample).

[0033] Figure 3 This is a schematic block diagram illustrating an embodiment of the device according to the present invention. Detailed Implementation

[0034] The inventors have discovered that the level of phosphorus (in the form of inorganic phosphate and / or organic phosphorus) in the water to be disinfected affects the efficiency of disinfection using percarboxylic acid; in water with a higher concentration of phosphorus, more percarboxylic acid is required to achieve effective disinfection.

[0035] Therefore, the present invention provides a method for disinfecting water, the water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, the method comprising:

[0036] (i) Treat water to reduce phosphorus concentration to 0.7 mg / L or lower; and

[0037] (ii) Contact the water treated in (i) with a certain amount of percarboxylic acid to provide disinfection.

[0038] Furthermore, the present invention provides a method for disinfecting water containing at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, the method comprising contacting the water with a certain amount of percarboxylic acid to provide disinfection, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water. Optionally, the amount of percarboxylic acid may also be controlled based on the concentration of total suspended solids (TSS) in the water, as the inventors have also found that the level of TSS in the water to be disinfected affects the efficiency of disinfection using percarboxylic acid.

[0039] Phosphorus can exist in water to be disinfected as free inorganic phosphate (e.g., in wastewater due to fertilizers in surface runoff or from household detergents) and as part of organic matter (e.g., as part of polyphosphate-accumulating microorganisms). In this invention, the concentration / amount of phosphorus refers to total phosphorus in water (including phosphorus present as dissolved inorganic “free” phosphate and phosphorus present as particulate, organic form).

[0040] Total suspended solids (TSS) in a water sample refer to suspended particles that are insoluble in water and can be captured by a filter. This includes both organic and inorganic suspended matter.

[0041] In some aspects and embodiments of the method of the present invention, the amount of percarboxylic acid in contact with water is controlled based on the concentration of phosphorus in the water (in the form of inorganic phosphate and / or organic phosphorus), and optionally also based on the amount of TSS in the water to be treated. These organic phosphorus / inorganic phosphate / TSS concentrations may be estimated or predicted concentrations (based on prior knowledge of the water to be treated and / or direct measurements of relevant factors), or measured amounts, although preferably the concentrations are measured concentrations.

[0042] Methods for measuring the concentration of organic phosphorus / phosphate in water, such as wastewater, are known in the art. For example, concentrations can be measured using colorimetric methods, such as those used in commercially available automated online analyzers. Total phosphorus in a sample can be measured using methods such as Hach Company's USEPA1 PhosVer. ® 3. The acid persulfate digestion method is used to measure total phosphate in the sample, which converts organophosphates into phosphates, and then the total phosphate is measured. Total phosphate can be measured using Hach Company's USEPA PhosVer 3. ® Ascorbic acid method for measurement.

[0043] The TSS of a water sample can also be measured using methods known in the art. For example, the water sample can be passed through a filter with a specific pore size (preferably 1.6 μm) and a known weight, then the filter and the trapped material can be dried to remove water from the filter, and the filter can be reweighed to establish the weight of the trapped TSS. (A suitable method is provided in Example 1.)

[0044] Therefore, in one embodiment, the method of the present invention includes measuring (a) the concentration of phosphorus in water and / or (b) the concentration of total suspended solids in water. This measurement can be performed offline, wherein a water sample is taken and analyzed in a separate process, either next to or away from the water being treated. However, the measurement is preferably performed in-line or online. Both in-line and online measurements are forms of in-situ measurements. Online measurements are not performed directly in the main process line, but rather in a built-in branch or bypass (e.g., a sampling loop) into which the water sample to be treated is automatically fed. In-line measurements are performed directly in the main process line, which requires placing a probe or sampling interface (or a pre-positioned probe or sampling interface) directly into or collinear with the process flow. For measurement methods requiring additional reagents to measure organophosphorus / phosphate / TSS levels (e.g., colorimetric methods as described above), an online measurement configuration is preferred.

[0045] The measurements in the method of the present invention can be performed once, or at regular or irregular time intervals. (In particular, this can be performed when the method involves treating water in a continuous or semi-continuous flow). For example, the concentration in the water can be measured at regular intervals of 1 to 5 minutes, or at regular intervals of 10 minutes, 20 minutes, 30 minutes, every hour, every 2 hours, every 4 hours, every 6 hours, every 12 hours, or every 24 hours. Alternatively, the concentration can be measured at least once every half hour to at least once a week. Preferably, the phosphorus concentration is measured at least once a day. Preferably, the TSS concentration is measured at least once every half hour.

[0046] In a preferred embodiment, the measurement includes measuring the concentration of inorganic phosphate in the water.

[0047] In one aspect / implementation of the invention, the method includes treating water to reduce the phosphorus concentration before the use of percarboxylic acid, and optionally further treating the water to reduce the total suspended solids concentration. For example, treating water to reduce the phosphorus concentration may include phosphorus precipitation, coagulation, biological removal, and / or physical removal. Preferably, the treatment includes contacting the water with a reagent that acts as a precipitant and / or coagulator to form phosphorus precipitates and / or phosphorus coagulates, and removing the precipitates and / or coagulates by sedimentation and / or filtration. The same reagent can act as both a precipitant and a coagulator, and any mechanism is suitable for the invention. For example, a reagent that causes phosphorus present in water as inorganic phosphates can also cause coagulation of organic matter containing organic phosphorus. In one embodiment, the treatment includes contacting the water with a source of calcium, iron, aluminum, or rare earth metal ions that act as a precipitant / coagulator to achieve phosphorus precipitation / coagulation. Preferably, the water is contacted with a source of iron and / or aluminum ions. The precipitates / coagulates formed in this manner can be removed by sedimentation and / or filtration.

[0048] Alternatively or additionally, the method may include treating the water to reduce its phosphorus concentration by using microorganisms to assimilate or remove phosphorus. This may be followed by additional steps to remove the microorganisms from the water.

[0049] Before contacting water with the stated amount of percarboxylic acid, the concentration of phosphorus (i.e., phosphorus including organic phosphorus and inorganic phosphate) is reduced to 0.7 mg / L or less, 0.5 mg / L or less, preferably 0.3 mg / L or less, more preferably 0.1 mg / L or less. Alternatively, before contacting water with the stated amount of percarboxylic acid, the concentration of phosphorus is reduced to 0.03-0.7 mg / L, 0.03-0.5 mg / L, preferably 0.03-0.3 mg / L, more preferably 0.03-0.1 mg / L.

[0050] This method involves treating water to reduce the amount of total suspended solids (TSS), which may include one or more of the following: screening, agglomeration, sedimentation, biological filtration, and treatment in an oxidation tank. Suitable chemicals for reducing TSS in wastewater are known in the art. Typical chemicals include polymers such as polyacrylamide, which can cause smaller particles to flocculate to form larger solids, and metal ions such as iron or aluminum, which can cause TSS coagulation. The resulting larger particles are more easily removed by physical separation techniques such as filtration, sedimentation, and separation.

[0051] Preferably, the total suspended solids (TSS) concentration is reduced to 20 mg / L or less, preferably 10 mg / L or less, before contacting the water with the percarboxylic acid. Alternatively, the TSS concentration is reduced to 0.1 mg / L to 20 mg / L, or preferably 0.1 mg / L to 10 mg / L, before contacting the water with the percarboxylic acid. As mentioned above, the TSS concentration can be determined, for example, using a filter with a pore size of 1.6 μm.

[0052] disinfect

[0053] Regardless of the disinfection technology used, disinfection performance is primarily determined by the concentration of residual disinfectant. The term "residual disinfectant concentration" used in this article refers to the concentration of disinfectant after a period of contact (or exposure) with the water to be treated. Therefore, maintaining a threshold concentration of residual disinfectant dynamically during the disinfection process will ensure consistent disinfection performance.

[0054] In the disinfection method of the present invention, contacting water with percarboxylic acid includes adding percarboxylic acid to the water. As described above, in the method of the present invention, the amount of percarboxylic acid in contact with the water can be controlled based on the concentration of phosphorus in the water, i.e., the amount of percarboxylic acid added to the water is controlled based on the concentration of phosphorus in the water. Optionally, the amount of percarboxylic acid in contact with the water can also be controlled based on the concentration of TSS in the water.

[0055] Obviously, in the method of the present invention, the amount of water should also be considered in determining the amount of percarboxylic acid in contact with water, since the purpose is to provide disinfection. Specifically, in the method of the present invention, the amount of percarboxylic acid is controlled based on the volume of water being treated. More specifically, in cases where the method of the present invention relates to the disinfection of flowing water, the volume of water being treated is determined based on the water flow rate; that is, the flow rate can be used to determine the amount of percarboxylic acid in contact with water.

[0056] In one embodiment of the invention, the amount of percarboxylic acid in contact with water is controlled solely based on the amount of water, such as volume, flow rate, etc., and the concentration of phosphorus in the water. In another embodiment, the amount of percarboxylic acid in contact with water is controlled solely based on the amount of water, such as volumetric flow rate, the concentration of phosphorus in the water, and the concentration of TSS.

[0057] In other implementations, many other factors are used to determine the amount of percarboxylic acid used for disinfection. Specifically, it is known that variations in water quality and quantity, as well as numerous side reactions between disinfectants and water contaminants, can reduce the concentration of residual disinfectants and thus adversely affect disinfection performance. For example, when added to wastewater, PFAs and PAAs experience an initial rapid depletion (i.e., instantaneous disinfectant demand), followed by a more gradual decline. Poor water quality and water contaminants can accelerate both the initial depletion and subsequent decline. Therefore, these characteristics may also need to be taken into account in controlling the amount of percarboxylic acid in contact with water.

[0058] The disinfection method of the present invention may include a single addition of percarboxylic acid controlled based on the concentration of phosphorus / phosphate and / or the concentration of TSS. Alternatively, the disinfection method may include adding percarboxylic acid to water multiple times, and one or more of these additions may be controlled based on the concentration of phosphorus and / or the concentration of TSS in the water to be treated. Furthermore, the disinfection method may include continuously adding percarboxylic acid to water, and the control may include one or more adjustments to the amount and / or rate of percarboxylic acid added during the period of continuous addition.

[0059] Percarboxylic acid can be contacted with water at an amount of 0.1-8 mg / L, preferably 0.1-6 mg / L, and more preferably 0.2-4 mg / L (i.e., the concentration reached at the addition point). Specifically, when the percarboxylic acid is performic acid, the performic acid can be contacted with water at an amount of 0.1-2 mg / L, preferably 0.1-1.5 mg / L, and more preferably 0.2-1 mg / L. When the percarboxylic acid is peracetic acid, the peracetic acid can be contacted with water at an amount of 0.4-8 mg / L, preferably 0.4-6 mg / L, and more preferably 0.8-4 mg / L.

[0060] Water to be treated

[0061] The water to be treated is not particularly limited and can be any water or aqueous solution that requires disinfection, i.e., because it contains at least one microorganism. The water to be treated can include raw water (e.g., surface water from lakes, oceans, or rivers), drainage, water used in agriculture, rainwater, wastewater (including municipal or industrial wastewater), or any mixture of the above. In some instances, the water may include industrial wastewater. In this context, the term "industrial" can refer to the pulp and paper industry, the petroleum industry, the mining industry, the food industry, or any other applicable industry. The water to be treated typically includes one or more contaminants such as bacteria, viruses, and other non-living organic matter.

[0062] Wastewater treatment

[0063] In a preferred embodiment, the water to be treated includes wastewater. Therefore, the disinfection method according to the invention can be carried out within a wastewater treatment system or plant. The wastewater to be treated may include municipal wastewater, sewage, and / or industrial wastewater.

[0064] Municipal wastewater or sewage treatment typically involves the following sequential processes: preliminary treatment, primary treatment, secondary treatment, and tertiary treatment. These are well known to those skilled in the art in wastewater treatment and water purification, and are discussed further below.

[0065] Preliminary treatment can remove coarse and large suspended matter that can be easily collected from raw sewage or wastewater from any pumps and sewage lines before they damage or clog primary treatment equipment, for example by screening and / or crushing.

[0066] Primary treatment is designed to remove coarse, suspended, and floating solids from raw wastewater or sewage. Primary treatment may include screening to capture solids and gravity settling to remove suspended solids (which are then removed and collected as sludge). The settling process can be accelerated by using chemicals. Total suspended solids (TSS) concentration is a key indicator of primary treatment. TSS represents the percentage by weight of fine particulate matter remaining suspended per unit volume of water. Primary treatment can reduce TSS concentration to 40-50%.

[0067] Following primary treatment, wastewater can be directed to secondary treatment, which typically includes biological treatment steps and settling. Specifically, the primary effluent may undergo activated sludge technology, in which the effluent is aerated and aerobic microorganisms metabolize organic matter into carbon dioxide and water and multiply to form a microbial community. Organic nitrogen compounds can be converted into ammonia and subsequently into nitrates. Secondary settling tanks / vessels allow microorganisms and solid waste to aggregate and settle into sludge. At least some of the collected sludge (activated sludge) can then be recycled as inoculum for further biological treatment of the incoming wastewater.

[0068] Secondary treatment can reduce TSS levels to 10% to 15%. Biochemical oxygen demand (BOD) is a further indicator of secondary treatment. BOD is a measure of the amount of oxygen required by aerobic microorganisms to break down organic matter present in a given water sample at a specific temperature and over a given time period. Secondary treatment typically reduces BOD to 10% to 15%.

[0069] Alternative or additional processes that may be performed during secondary treatment include biological filtration and oxidation ponds. Biological filtration requires the use of microorganisms immobilized on filters (such as sand filters, contact filters, or trickling filters) to break down organic matter and remove additional sediment. Oxidation ponds involve exposing wastewater to sunlight for an extended period of time through a large body of water (such as lagoons) to allow microorganisms to decompose organic matter.

[0070] Primary and secondary treatment are often sufficient for many purposes, and not all wastewater treatment plants use tertiary treatment. Those that do use tertiary treatment achieve more stringent levels of cleanliness to meet the demanding standards governing water reuse, especially in public water supplies. Tertiary treatment is also beneficial when facilities must discharge water into sensitive or fragile ecosystems such as estuaries, low-flow rivers, coral reefs, etc. Tertiary treatment may include filtration, disinfection, and the removal of nitrogen and phosphorus.

[0071] In view of the foregoing, the method of the present invention may include performing primary and / or secondary treatment of wastewater. In particular, such treatment may include reducing the concentration of TSS and / or phosphorus in the water (as described above) prior to disinfection with percarboxylic acid. Preferably, such treatment includes treating the secondary sedimentation inflow to reduce (a) the concentration of phosphorus in the water and optionally (b) the concentration of total suspended solids in the water before contacting the water with percarboxylic acid. In particular, this treatment may include contacting the secondary sedimentation inflow with an iron ion source during or after aeration to achieve phosphorus precipitation, and removing the precipitate by sedimentation and / or filtration.

[0072] The method may then further include performing tertiary treatment of the wastewater, wherein contacting the water with percarboxylic acid to provide disinfection is carried out during the tertiary treatment.

[0073] equipment

[0074] In another aspect, the present invention provides an apparatus comprising:

[0075] At least one processor; and

[0076] At least one memory including computer program code, the at least one memory and the computer program code being configured together with the at least one processor to cause the device to perform the method of the present invention.

[0077] In particular, the device can be considered as a control device for controlling at least a part of the disinfection method.

[0078] Figure 3 This is a block diagram of a device (18) according to an example of the present invention. The control device (18) is adapted to perform at least some of the operations described herein. Reference Figure 3 The device (18) includes at least one processor (28), at least one memory (29), a communication interface (32), and a user interface (31). The control device may also include additional internal circuitry and components necessary to perform the tasks described herein. The device is arranged to control the amount of percarboxylic acid in contact with water to provide disinfection using data regarding the concentration of phosphorus in the water and / or data regarding the concentration of TSS in the water. Specifically, the device is arranged to control the amount of percarboxylic acid added to the water from the metering device (14).

[0079] Regarding data on phosphorus concentration in the water to be treated, the device (18) is arranged to receive output data from a first measuring device (11) that measures the phosphorus concentration in the water. Optionally, regarding data on TSS concentration in the water to be treated, the device (18) is arranged to receive output data from a third measuring device (13) that measures the TSS concentration in the water. Additionally, the device (18) is arranged to receive output data from a second measuring device (12) configured to measure the percarboxylic acid concentration in the water.

[0080] The device (18) may include a communication interface (32) for connecting the control device to a data communication system and enabling data communication with the device. The communication interface (32) may include wired and / or wireless communication circuitry, such as Ethernet, wireless LAN, Bluetooth, GSM, CDMA, WCDMA, LTE, 5G circuitry, and / or the like. The communication interface may be integrated into the control device (18) or provided as part of an adapter, card, etc., that can be attached to the control device (20). The communication interface (32) may support one or more different communication technologies. Alternatively, the device (18) may include more than one communication interface (32).

[0081] The user interface (31) may include circuitry for receiving user input from the control device (18), for example via a keyboard, a graphical user interface displayed on the device's screen, voice recognition circuitry, or an accessory device such as headphones, and for providing output to the user via, for example, a graphical user interface or a speaker. The device may be remotely operated.

[0082] At least one processor (28) may be coupled to at least one memory (29). At least one processor (28) may be configured to execute appropriate computer program code to implement one or more aspects described herein. At least one processor (28) may be a central processing unit (CPU), a microprocessor, a digital signal processor (DSP), a graphics processing unit, an application-specific integrated circuit (ASIC), a field-programmable gate array, a microcontroller, or a combination of such elements.

[0083] At least one memory (29) may include working memory (30) and persistent (non-volatile, N / V) memory (33) configured to store computer program code (34) and data (35). Memory (33) may include any one or more of the following: read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), random access memory (RAM), flash memory, data disk, optical storage, magnetic storage, smart card, solid-state drive (SSD), etc. Device (18) may include other possible components for use in software and hardware-assisted execution of the task designed to be performed.

[0084] The device (18) may include multiple memories (33). The memories (33) may be constructed as part of the control device (18) or as attachments to be inserted into slots, ports, etc. of the device (18) by a user, another person, or a robot. The memories (33) may serve only the purpose of storing data or may be constructed as part of the device (18) for other purposes such as processing data.

[0085] Those skilled in the art will understand that, in addition to Figure 3 In addition to the components shown, the control device (18) may also include other components such as a microphone, a display, and additional circuitry such as input / output (I / O) circuitry, memory chips, application-specific integrated circuits (ASICs), and processing circuitry for specific purposes such as source encoding / decoding circuitry, channel encoding / decoding circuitry, encryption / decryption circuitry, etc. Furthermore, the control device (18) may include a disposable or rechargeable battery (not shown) to power the device (18) if an external power source is unavailable. It should also be noted that... Figure 3 Only one device (18) is shown, but some implementations can be implemented in a cluster of devices shown.

[0086] system

[0087] In another aspect, the present invention provides a water treatment system comprising the aforementioned equipment, the system comprising:

[0088] The first quantitative feeding device is configured to feed a reagent, which is a precipitant and / or coagulant, into water to form phosphorus precipitates and / or coagulates.

[0089] The second quantitative feeding device is configured to feed percarboxylic acid into water, and

[0090] A first measuring device is configured to measure the concentration of phosphorus in water and generate output data related to the measured phosphorus concentration.

[0091] The device is configured and arranged to receive output data related to the measured concentration of phosphorus from a first measuring device, monitor the measured concentration of phosphorus in water, and adjust the amount of the reagent fed into the water by a first quantitative feeding device and / or adjust the amount of percarboxylic acid fed into the water by a second quantitative feeding device based on the measured concentration of phosphorus.

[0092] The first metering device can be configured to add or feed a precipitant / coagulant (i.e., the ion source described above) into water. The first metering device may include one or more pumps or valves that facilitate the delivery of the ion source into the water optionally via one or more lines. The first metering device can be operated manually or automatically. The ion source can be added or fed into the water continuously or at regular intervals at a constant rate, or the metering can be adjusted based on a measured concentration measured by a first measuring device.

[0093] The second metering device can be configured to add or feed percarboxylic acid into the water stream. This metering device may include one or more pumps or valves that facilitate the delivery of percarboxylic acid into the water optionally via one or more lines. The second metering device can be operated manually or automatically.

[0094] PAA is commercially available as an acidic quaternary equilibrium mixture of acetic acid, hydrogen peroxide (H2O2) and water as shown in reaction (1) below, and can therefore be fed into water as an equilibrium mixture.

[0095]

[0096] Due to the greater instability and faster decomposition time of PFA, it may be necessary to generate PFA immediately before use. Preferably, PFA is generated in situ (i.e., at the water treatment site). Therefore, a second metering device may include a reaction vessel in which PFA is generated. In other embodiments, PFA is generated outside the water treatment system and directly and rapidly transferred to the metering device for feeding into the water. A preferred method of PFA preparation involves mixing formic acid with hydrogen peroxide according to reaction (2) below, optionally in the presence of an acid catalyst such as sulfuric acid, ascorbic acid, or boric acid. If the molar ratio of formic acid to hydrogen peroxide is increased, or by removing water from the reaction, the equilibrium of reaction (2) below can shift in favor of PFA formation.

[0097]

[0098] Percarboxylic acid can be fed into the water continuously (i.e., without interruption) or at regular predetermined time intervals. The amount of percarboxylic acid fed into the water can be adjusted (i.e., modified) based on the measured level of phosphorus in the water (and optionally TSS) and further optionally also based on the measured level of residual percarboxylic acid. As mentioned above, the level of residual percarboxylic acid in the water provides an indication of disinfection efficacy.

[0099] In some instances, the feeding of percarboxylic acid into water is automated. In these instances, and further reference... Figure 3The aforementioned control device (18) can be operatively connected to the percarboxylic acid metering device (14). The control device (18) can be configured and arranged to receive output data related to the concentration of phosphorus in the water from the first measuring device (19), and to adjust the feed of percarboxylic acid from the second metering device (14) into the water based on such output data. This ensures that any changes in phosphorus concentration on the disinfection performance of the percarboxylic acid are minimized or offset by adjusting the amount of percarboxylic acid fed into the water for disinfection.

[0100] Therefore, based on the output data received from the first measuring device (11), the control device (18) can detect an increase in phosphorus concentration above a predefined threshold concentration and cause the second metering device (14) to increase the amount of percarboxylic acid fed into the water to be treated within a given time period until the phosphorus concentration returns to the predefined threshold. This can be achieved, for example, by increasing the pump speed or opening a valve that facilitates the delivery of percarboxylic acid from the second metering device (14) to the water to be treated. Conversely, based on the output data received from the first measuring device (11), the control device (18) can detect a decrease in phosphorus concentration below a predefined threshold concentration and cause the second metering device (14) to reduce the amount of percarboxylic acid fed into the water to be treated within a given time period to avoid unnecessary depletion of percarboxylic acid and an increase in residual percarboxylic acid concentration exceeding regulatory limits. This can be achieved, for example, by reducing the pump speed or closing a valve that would otherwise facilitate the delivery of percarboxylic acid from the second metering device (14) to the water to be treated.

[0101] As described above, appropriate computer program code (34) executed by the processor (28) and stored in the memory (29) can determine, based on the output measurement data received from the first measuring device (11), whether the measured phosphorus concentration is higher or lower than a predefined threshold, and the necessary adjustments to the amount of percarboxylic acid fed into the water to be treated, as described herein. Therefore, the control device (18) can be configured and arranged to compare the measured phosphorus concentration with a predefined threshold phosphorus / phosphate concentration, and can be configured and arranged to adjust the performance of the second metering device (14).

[0102] In further examples, the metering of percarboxylic acid can also be adjusted, either additionally or alternatively, based on the concentration of residual percarboxylic acid. In these examples, a second measuring device (12) can be provided to measure the residual concentration of percarboxylic acid. A control device (18) can be configured and arranged to receive output data from the second measuring device (12) relating to the concentration of residual percarboxylic acid, and to regulate the feed of percarboxylic acid from the second metering device (14) into the water based on such output data. Thus, for example, based on the output data received from the second measuring device (12), the control device (18) can detect an increase in the concentration of residual percarboxylic acid above a predefined threshold concentration, and cause the second metering device (14) to reduce the amount of percarboxylic acid fed into the water to be treated over a given time period to avoid unnecessary depletion of percarboxylic acid and an increase in the concentration of residual percarboxylic acid exceeding regulatory limits, and to restore the concentration of residual percarboxylic acid to the predefined threshold. This can be achieved, for example, by reducing the pump speed or closing valves that would otherwise facilitate the delivery of percarboxylic acid from the second metering device (14) into the water to be treated. Conversely, based on the output data received from the second measuring device (12), the control device (18) can detect that the concentration of residual percarboxylic acid has decreased to below a predefined threshold concentration, and cause the second metering device (14) to increase the amount of percarboxylic acid fed into the water to be treated over a given time period to maintain the required disinfection efficacy. This can be achieved, for example, by increasing the pump speed or opening a valve that facilitates the delivery of percarboxylic acid from the second metering device (14) to the water to be treated. In examples of in-situ synthesis of percarboxylic acid, the change in the metering of percarboxylic acid can be achieved by a corresponding change in the productivity of percarboxylic acid (e.g., by changing the amount of reactants available to produce percarboxylic acid).

[0103] The predefined threshold concentration of residual percarboxylic acid (PFA) is determined based on applicable regulatory limits in the region where the water treatment system is located. In some embodiments, the predefined threshold concentration of PFA may be 0.1 mg / L to 2 mg / L, 0.1 mg / L to 1 mg / L, or 0.2 mg / L to 0.8 mg / L. In some embodiments, the predefined threshold concentration of PAA may be 0.4 mg / L to 8 mg / L, 0.4 mg / L to 4 mg / L, or 1.6 mg / L to 3.2 mg / L.

[0104] In some embodiments, the water treatment method of the present invention is a continuous method. In an example of the invention, a PFA solution is contacted with water at a baseline concentration based on the amount of active PFA, such as 0.1 to 3 mg / L or 0.2 to 2 mg / L, 0.3 to 1.5 mg / L or 0.3 to 1 mg / L (i.e., the PFA concentration before it is consumed at the point of addition to the water). In another example of the invention, a PAA solution is contacted with water at a baseline concentration based on the amount of active PAA, such as 0.4 to 12 mg / L or 0.8 to 8 mg / L, 1.2 to 6.0 mg / L or 1.2 to 4 mg / L (i.e., the PAA concentration before it is consumed at the point of addition to the water). Percarboxylic acid can be continuously fed into the water to be treated from a second metering device (14) in which percarboxylic acid can be generated at the above-mentioned active concentration. The metering of percarboxylic acid can be adjusted as described above in response to changes in phosphorus concentration and / or residual percarboxylic acid concentration.

[0105] As described above, the PID controller continuously calculates the error value as the difference between the predefined set concentration of residual percarboxylic acid and the measured concentration of percarboxylic acid, and then applies corrections based on proportional, integral, and derivative terms. The controller may attempt to minimize this error over time by adjusting its output (e.g., by adjusting the speed of the pump delivering the percarboxylic acid) so that the concentration of percarboxylic acid does not exceed a predefined threshold concentration.

[0106] Measurement of percarboxylic acid

[0107] In the water treatment method according to the invention, the level of residual percarboxylic acid (PFA) can preferably be measured and monitored continuously and in real time to detect any fluctuations in concentration deviating from the threshold concentration of residual PFA. In this context, "continuous" means measuring the level of PFA at regular, repetitive intervals without interruption. For example, the level of residual PFA can be measured and monitored at regular intervals, such as every 2 minutes, every 3 minutes, every 4 minutes, every 5 minutes, every 10 minutes, every 30 minutes, or every hour. The measurements can be performed online or in-line.

[0108] Percarboxylic acids can be measured manually or automatically. They can be measured using standard methods, including amperometric techniques and colorimetric methods, such as the well-known DPD (N,N-diethyl-p-phenylenediamine) method. DPD kits and photometers are commercially available. Examples of DPD analyzers that can be used for percarboxylic acid measurements include Hach. ® CL-17 analyzer, Hach ® CL-17sc analyzer or Xylem ® The 3017M analyzer can also be used to measure percarboxylic acids using the standard Reflectoquant peracetic acid test.

[0109] The level of residual percarboxylic acid can be measured by a second measuring device (14) at any process location after the percarboxylic acid is fed into the water. Preferably, the measurement begins after a sufficient contact time (i.e., the time between the addition of the percarboxylic acid to the water and the measurement) has elapsed. A contact time of at least 5 minutes, 10 minutes, 20 minutes, or 30 minutes is desired. In some instances, a contact time of at least 1 hour or 2 hours is provided. In a continuous flow system, this means performing the measurement at a flow distance of at least 1 minute, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 1 hour, or 2 hours downstream of the point where the percarboxylic acid is fed into the water.

[0110] Although at least some aspects of the embodiments described herein with reference to the accompanying drawings include computer processes executed in a processing system or processor, the invention also extends to computer programs, particularly computer programs on or in a carrier suitable for carrying out the invention. The program may be non-transitory source code, object code, code between source code and object code (e.g., in a partially compiled form), or any other non-transitory form suitable for implementing the process according to the invention. The carrier may be any entity or device capable of carrying the program. For example, the carrier may include storage media such as solid-state drives (SSDs) or other semiconductor-based RAM; ROMs such as CD ROMs or semiconductor ROMs; magnetic recording media such as floppy disks or hard disks; conventional optical storage devices, etc.

[0111] use

[0112] The present invention also provides the use of phosphorus precipitants and / or coagulants for reducing the amount of percarboxylic acid required to disinfect water containing at least one microorganism, wherein the water further contains a certain concentration of phosphorus in the form of inorganic phosphate and / or organic phosphorus, and wherein the use comprises reducing the concentration of phosphorus in the water by contacting the water with the precipitant and / or coagulant to precipitate and / or coagulate phosphorus and separating the precipitate and / or coagulate from the water.

[0113] Specifically, the phosphorus precipitant / coagulant can be a source of calcium, iron, aluminum, or rare earth metal ions that can be used to form phosphorus precipitates and / or phosphorus coagulates. Preferably, the reagent is a source of iron and / or aluminum ions. The reagent can be used as described in any of the methods herein.

[0114] The following is intended as an example only and does not limit the content of this disclosure.

[0115] Example

[0116] Example 1

[0117] The efficacy of performic acid (PFA) was tested in wastewater with varying total suspended solids (TSS) and phosphorus (including inorganic phosphates and organic phosphorus) concentrations.

[0118] Purified wastewater from a Finnish wastewater treatment plant was used, and dirty influent wastewater and / or sludge from the plant in question were added to the water to adjust the TSS and phosphorus concentrations to the desired levels (as shown in the table below).

[0119] Two methods were used to measure phosphorus. The presence of phosphates (reactive orthophosphates, PO4) in the sample was also considered. 3- The measurements were performed using the commercially available USEPA PhosVer 3 method (No. 8048) from Hach, following the manufacturer's instructions. The determined values ​​represent "free phosphate" in the sample. It should be noted that, generally speaking, the phosphorus concentration is approximately one-third of the phosphate concentration, therefore the measured concentration is divided by three to obtain the values ​​for "free phosphate as phosphorus" shown in the table below.

[0120] Total phosphorus as phosphate was measured using an alternative method from Hach, namely USEPA PhosVer 3, using persulfate digestion (No. 8190). This method converts organic phosphorus into phosphate (so that all phosphorus in the sample is present as phosphate), and then measures the amount of phosphate present. The phosphate concentration determined by this method is also divided by 3 to obtain the phosphorus concentration shown in the table below.

[0121] Total suspended solids (TSS) were determined as follows: 100–200 ml of sample was filtered through a weighing glass fiber filter with a pore size of 1.6 μm. The solid material and filter were dried at +105 °C for 2 hours. The filter was weighed, and the TSS content was calculated based on the sample volume and the weight of the material on the filter.

[0122] In addition, E. coli cells (grown overnight on an agar plate and suspended in a 0.9% NaCl solution) were added to the water to ensure that the bacterial count was in the range of 1,000,000-2,000,000 cfu / ml (total bacteria) and 100,000-700,000 cfu / ml (E. coli).

[0123] Add 0, 0.5, 1, 2, or 4 mg / L PFA to the test water, and after a 15-minute contact time, count the surviving cells using Total aerobic count petrifilms (3M) and Compact dry EC (Nissui Pharma Solutions). Incubate the bacteria overnight at +37°C and calculate the results.

[0124] The results are shown in Table 1 below and Figure 1 and 2 middle.

[0125]

[0126] Table 1 – Efficacy of Performic Acid (PFA)

[0127] from Figure 1 and Figure 2 It can be seen that when phosphorus and TSS levels are high, a larger amount of PFA is required to achieve effective disinfection (i.e., to reduce bacterial cell counts to an acceptable level).

[0128] The present invention also provides the following aspects and embodiments:

[0129] 1. A method for disinfecting water, said water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, said method comprising:

[0130] (i) Treat water to reduce phosphorus concentration to 0.7 mg / L or lower; and

[0131] (ii) Contact the water treated in (i) with a certain amount of percarboxylic acid to provide disinfection.

[0132] 2. The method according to clause 1, wherein (i) includes treating water to reduce the concentration of total suspended solids.

[0133] 3. The method according to clause 1 or 2, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water subsequently treated (i) and optionally also based on the concentration of total suspended solids in the water treated.

[0134] 4. The method according to any one of clauses 1 to 3, including measuring the concentration of phosphorus in water before and / or after (i).

[0135] 5. The method according to any one of clauses 1 to 4, comprising measuring the concentration of total suspended solids in water.

[0136] 6. The method according to clause 4 or 5, wherein the measurement of phosphorus concentration occurs at least once per hour to at least once per week, and preferably wherein the measurement occurs at least once per day.

[0137] 7. The method according to any one of clauses 4 to 6, wherein the concentration of total suspended solids is measured at least once every half hour to at least once a week, and preferably wherein the measurement is performed at least once every half hour.

[0138] 8. The method according to any one of clauses 4 to 7, comprising varying the rate of addition of percarboxylic acid to water based on the measured concentration of phosphorus and optionally based on the measured concentration of total suspended solids.

[0139] 9. The method according to any one of clauses 1 to 8, wherein treating water to reduce the concentration of phosphorus includes treating the water to achieve precipitation, coagulation, biological removal and / or physical removal of phosphorus, preferably wherein the treatment includes contacting the water with a reagent as a precipitant and / or coagulator to form phosphorus precipitates and / or coagulates, and removing the precipitates and / or coagulates by sedimentation and / or filtration.

[0140] 10. The method according to clause 9, wherein water is contacted with a precipitant and / or a coagulant, said precipitant and / or coagulant being a source of calcium, iron, aluminum or rare earth ions, and preferably a source of iron and / or aluminum ions.

[0141] 11. The method according to any one of clauses 1 to 10, wherein treating water to reduce the concentration of phosphorus includes using microorganisms to assimilate or remove phosphorus from the water.

[0142] 12. The method according to any one of clauses 2 to 11, wherein treating water to reduce the concentration of total suspended solids comprises one or more of the following: screening, agglomeration, sedimentation, biofiltration and / or treatment in an oxidation tank.

[0143] 13. The method according to any one of clauses 1 to 12, wherein the percarboxylic acid comprises performic acid and / or peracetic acid, and preferably wherein the percarboxylic acid is performic acid.

[0144] 14. The method according to any one of clauses 1 to 13, wherein the concentration of phosphorus is reduced to 0.5 mg / L or less, preferably 0.3 mg / L or less, more preferably 0.1 mg / L or less, before contacting water with the amount of percarboxylic acid.

[0145] 15. The method according to any one of clauses 2 to 14, wherein the concentration of total suspended solids is reduced to 20 mg / L or less, preferably 10 mg / L or less, before contacting water with the amount of percarboxylic acid.

[0146] 16. The method according to any one of clauses 1 to 15, wherein the percarboxylic acid is formic acid and the formic acid is contacted with water in an amount of 0.1 to 2 mg / L, preferably 0.1 mg / L to 1.5 mg / L, more preferably 0.2 to 1.0 mg / L.

[0147] 17. The method according to any one of clauses 1 to 16, wherein the water comprises wastewater, and preferably wherein the method comprises performing primary and / or secondary treatment of the wastewater.

[0148] 18. The method according to clause 17, comprising treating the secondary sedimentation inflow to reduce (a) the concentration of phosphorus in the water and / or (b) the amount of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

[0149] 19. The method according to clause 18, comprising contacting the inflow with an iron ion source to form a phosphorus precipitate during or after aeration of the secondary sedimentation inflow, and removing the precipitate by sedimentation and / or filtration.

[0150] 20. The method according to any one of clauses 17 to 19, wherein the method further comprises performing tertiary treatment of the wastewater, optionally wherein:

[0151] (a) The tertiary treatment includes contacting the wastewater with an iron ion source to form a phosphorus precipitate, and removing the precipitate by sedimentation and / or filtration; or

[0152] (b) Percarboxylic acid is used to provide disinfection, which is performed during the tertiary treatment.

[0153] 21. A method for disinfecting water, said water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, said method comprising contacting the water with a certain amount of percarboxylic acid to provide disinfection, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water and optionally also based on the concentration of total suspended solids in the water.

[0154] 22. The method according to clause 21 includes treating the water to reduce (a) the concentration of phosphorus in the water and optionally (b) the concentration of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

[0155] 23. The method according to clause 21 or clause 22 includes measuring the concentration of phosphorus in the water before contacting the water with the amount of percarboxylic acid.

[0156] 24. The method according to any one of clauses 21 to 23, comprising measuring the concentration of total suspended solids in water before contacting the water with the amount of percarboxylic acid.

[0157] 25. The method according to clause 23 or clause 24, wherein the measurement of phosphorus concentration occurs at least once per hour to at least once per week, and preferably wherein the measurement occurs at least once per day.

[0158] 26. The method according to any one of clauses 23 to 25, wherein the concentration of total suspended solids is measured at least once every half hour to at least once a week, and preferably wherein the measurement is performed at least once every half hour.

[0159] 27. The method according to any one of clauses 23 to 26, comprising varying the rate of addition of percarboxylic acid to water based on the measured concentration of phosphorus and optionally based on the measured concentration of total suspended solids.

[0160] 28. The method according to any one of clauses 22 to 27, wherein treating water to reduce the concentration of phosphorus includes treating water to achieve precipitation, coagulation, biological removal and / or physical removal of phosphorus, preferably wherein said treatment includes contacting water with a reagent as a precipitant and / or coagulator to form phosphorus precipitates and / or coagulates, and removing said precipitates and / or coagulates by sedimentation and / or filtration.

[0161] 29. The method according to clause 28, wherein water is contacted with a precipitant and / or a coagulant, said precipitant and / or coagulant being a source of calcium, iron, aluminum or rare earth ions, and preferably a source of iron and / or aluminum ions.

[0162] 30. The method according to any one of clauses 22 to 29, wherein treating water to reduce the concentration of phosphorus includes using microorganisms to assimilate or remove phosphorus from the water.

[0163] 31. The method according to any one of clauses 22 to 30, wherein treating water to reduce the concentration of total suspended solids comprises one or more of the following: screening, agglomeration, sedimentation, biological filtration and treatment in an oxidation tank.

[0164] 32. The method according to any one of clauses 21 to 31, wherein the percarboxylic acid comprises performic acid and / or peracetic acid, and preferably wherein the percarboxylic acid is performic acid.

[0165] 33. The method according to any one of clauses 22 to 32, wherein the concentration of phosphorus is reduced to 0.7 mg / L or less, 0.5 mg / L or less, preferably 0.3 mg / L or less, more preferably 0.1 mg / L or less.

[0166] 34. The method according to any one of clauses 22 to 33, wherein the concentration of total suspended solids is reduced to 20 mg / L or less, preferably 10 mg / L or less, before contacting water with the amount of percarboxylic acid.

[0167] 35. The method according to any one of clauses 21 to 34, wherein the percarboxylic acid is formic acid and the formic acid is contacted with water in an amount of 0.1 to 2 mg / L, preferably 0.1 to 1.5 mg / L, more preferably 0.2 to 1.0 mg / L.

[0168] 36. The method according to any one of clauses 21 to 35, wherein the water includes wastewater, and preferably wherein the method includes performing primary and / or secondary treatment of the wastewater.

[0169] 37. The method according to clause 36 includes treating the secondary sedimentation inflow to reduce (a) the concentration of phosphorus in the water and / or (b) the amount of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

[0170] 38. The method according to clause 37, comprising contacting the inflow with an iron ion source to form a phosphorus precipitate during or after aeration of the secondary sedimentation inflow, and removing the precipitate by sedimentation and / or filtration.

[0171] 39. The method according to any one of clauses 36 to 38, wherein the method further comprises performing tertiary treatment of the wastewater, optionally wherein:

[0172] (a) The tertiary treatment includes contacting the wastewater with an iron ion source to form a phosphorus precipitate, and removing the precipitate by sedimentation and / or filtration; or

[0173] (b) Percarboxylic acid is used to provide disinfection, which is performed during the tertiary treatment.

[0174] 40. An apparatus comprising:

[0175] At least one processor; and

[0176] At least one memory including computer program code, the at least one memory and the computer program code being configured together with the at least one processor to cause the device to perform the method described in any one of items 1 to 39.

[0177] 41. A water treatment system comprising the apparatus described in claim 40, the system comprising:

[0178] A first quantitative feeding device is configured to feed a reagent, acting as a precipitant and / or coagulant, into water to form phosphorus precipitates and / or coagulates.

[0179] The second quantitative feeding device is configured to feed percarboxylic acid into water, and

[0180] A first measuring device is configured to measure the concentration of phosphorus in water and generate output data related to the measured phosphorus concentration.

[0181] The device is configured and arranged to receive output data from a first measuring device relating to the concentration of phosphorus being measured, monitor the level of phosphorus in the measured water, and adjust the amount of the reagent fed into the water by a first metering device and / or adjust the amount of percarboxylic acid fed into the water by a second metering device based on the measured phosphorus concentration.

[0182] 42. The system according to clause 41, wherein the system further comprises:

[0183] The second measuring device is configured to measure the concentration of percarboxylic acid in water and generate output data related to the measured concentration of percarboxylic acid.

[0184] Furthermore, the device is configured and arranged to receive output data from a second measuring device relating to the concentration of the measured percarboxylic acid, monitor the concentration of the measured percarboxylic acid in the water, and adjust the amount of percarboxylic acid fed into the water by a second metering device based on the concentration of the measured percarboxylic acid.

[0185] 43. The use of phosphorus precipitants and / or coagulants to reduce the amount of percarboxylic acid required to disinfect water containing at least one microorganism, wherein the water further contains a concentration of phosphorus in the form of inorganic phosphate and / or organic phosphorus, and wherein the use includes reducing the concentration of phosphorus in the water by contacting the water with the precipitant and / or coagulant to precipitate and / or coagulate phosphorus and separating the precipitate and / or coagulate from the water.

[0186] 44. The use as described in clause 43, wherein the use is as defined in any one of clauses 1 to 39.

[0187] Once the disclosure herein is given, other variations or uses of the technology disclosed will become apparent to those skilled in the art. This disclosure is not limited to the described embodiments, but only to the appended claims.

Claims

1. A method for disinfecting water, wherein the water contains at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, the method comprising: (i) Treat the water to reduce the phosphorus concentration to 0.7 mg / L or lower; as well as (ii) Contact the water treated in (i) with a certain amount of percarboxylic acid to provide disinfection.

2. The method according to claim 1, wherein, (i) This includes treating water to reduce the concentration of total suspended solids.

3. The method according to claim 1 or claim 2, wherein, The amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water treated after (i), and optionally also based on the concentration of total suspended solids in the treated water.

4. The method according to any one of claims 1 to 3, wherein the method comprises: (a) Measure the concentration of phosphorus in the water before and / or after (i); and / or (b) Measure the concentration of total suspended solids in water.

5. A method for disinfecting water, said water comprising at least one microorganism and phosphorus present in the form of inorganic phosphate and / or organic phosphorus, said method comprising contacting said water with a certain amount of percarboxylic acid to provide disinfection, wherein the amount of percarboxylic acid is controlled based on the concentration of phosphorus in the water, and optionally also based on the concentration of total suspended solids in the water.

6. The method of claim 5, comprising treating the water to reduce (a) the concentration of phosphorus in the water and optionally (b) the concentration of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

7. The method according to claim 5 or claim 6, comprising: (a) Measure the concentration of phosphorus in the water before contacting the water with the stated amount of percarboxylic acid; and / or (b) Measure the concentration of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

8. The method according to claim 4 or claim 7, wherein: (a) The concentration of phosphorus is measured at least once per hour to at least once per week, and preferably, the measurement is performed at least once per day; and / or (b) The concentration of total suspended solids is measured at least once every half hour to at least once a week, and preferably the measurement is performed at least once every half hour.

9. The method of claim 4, claim 7 or claim 8, further comprising modifying the rate of addition of percarboxylic acid to water based on the measured concentration of phosphorus, and optionally modifying the rate of addition of percarboxylic acid to water based on the measured concentration of total suspended solids.

10. The method according to any one of claims 1 to 4 or 6 to 9, wherein treating water to reduce the concentration of phosphorus comprises treating water to achieve precipitation, coagulation, biological removal and / or physical removal of phosphorus, preferably wherein the treatment comprises contacting water with a reagent as a precipitant and / or coagulator to form phosphorus precipitates and / or coagulates, and removing the precipitates and / or coagulates by sedimentation and / or filtration.

11. The method according to claim 10, wherein, Water is brought into contact with a precipitant and / or a coagulant, said precipitant and / or coagulant being a source of calcium, iron, aluminum or rare earth ions, and preferably a source of iron and / or aluminum ions.

12. The method according to any one of claims 1 to 4 or claims 6 to 11, wherein treating water to reduce the concentration of phosphorus comprises using microorganisms to assimilate or remove phosphorus from the water.

13. The method according to any one of claims 1 to 4 or claims 6 to 12, wherein treating water to reduce the concentration of total suspended solids comprises one or more of the following: screening, agglomeration, sedimentation, biofiltration, and treatment in an oxidation tank.

14. The method according to any one of claims 1 to 13, wherein, The percarboxylic acid includes performic acid and / or peracetic acid, and preferably the percarboxylic acid is performic acid.

15. The method according to any one of claims 1 to 4 or 6 to 14, wherein: (a) Before contacting water with the stated amount of percarboxylic acid, the concentration of phosphorus is reduced to 0.7 mg / L or less, 0.5 mg / L or less, preferably 0.3 mg / L or less, more preferably 0.1 mg / L or less; and / or (b) Before contacting water with the amount of percarboxylic acid, reduce the concentration of total suspended solids to 20 mg / L or less, preferably 10 mg / L or less.

16. The method according to any one of claims 1 to 15, wherein, The percarboxylic acid is performic acid, and the performic acid is in contact with water at an amount of 0.1-2 mg / L, preferably 0.1 mg / L to 1.5 mg / L, more preferably 0.2-1.0 mg / L.

17. The method according to any one of claims 1 to 16, wherein, The water includes wastewater, and preferably the method includes primary and / or secondary treatment of the wastewater.

18. The method of claim 17, further comprising treating the secondary sedimentation inflow to reduce (a) the concentration of phosphorus in the water and / or (b) the amount of total suspended solids in the water before contacting the water with the amount of percarboxylic acid.

19. The method of claim 18, comprising contacting the inflow with an iron ion source to form a phosphorus precipitate during or after aeration of the secondary sedimentation inflow, and removing the precipitate by sedimentation and / or filtration.

20. The method according to any one of claims 17 to 19, wherein the method further comprises tertiary treatment of the wastewater, optionally wherein: (a) The tertiary treatment includes contacting the wastewater with an iron ion source to form a phosphorus precipitate, and removing the precipitate by sedimentation and / or filtration; or (b) Disinfection is provided using percarboxylic acid during tertiary treatment.

21. An apparatus comprising: At least one processor; as well as At least one memory including computer program code, the at least one memory and the computer program code being configured together with the at least one processor to cause the device to perform the method according to any one of claims 1 to 20.

22. A water treatment system comprising the apparatus of claim 21, the system comprising: The first metering feeder is configured to feed a reagent as a precipitant and / or coagulant into the water to form phosphorus precipitates and / or coagulates. The second quantitative feeding device is configured to feed percarboxylic acid into the water, and A first measuring device is configured to measure the concentration of phosphorus in water and generate output data related to the measured phosphorus concentration. The device is configured and arranged to receive output data from the first measuring device relating to the measured concentration of phosphorus, monitor the measured level of phosphorus in the water, and adjust the amount of the reagent fed into the water by the first metering device and / or adjust the amount of the percarboxylic acid fed into the water by the second metering device based on the measured concentration of phosphorus.

23. The system of claim 22, wherein the system further comprises: The second measuring device is configured to measure the concentration of percarboxylic acid in water and generate output data related to the measured concentration of percarboxylic acid. And wherein the device is configured and arranged to receive output data from the second measuring device relating to the concentration of the measured percarboxylic acid, monitor the concentration of the measured percarboxylic acid in the water, and adjust the amount of percarboxylic acid fed into the water by the second metering device based on the concentration of the measured percarboxylic acid.

24. The use of phosphorus precipitants and / or coagulants to reduce the amount of percarboxylic acid required to disinfect water containing at least one microorganism, wherein the water also contains a concentration of phosphorus in the form of inorganic phosphate and / or organic phosphorus, and wherein the use includes reducing the concentration of phosphorus in the water by contacting the water with the precipitant and / or coagulant to precipitate and / or coagulate phosphorus and to separate the precipitate and / or coagulate from the water.

25. The use according to claim 24, wherein the use is as defined in any one of claims 1 to 20.

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