Water treatment system and water treatment method

Abstract

Provided is a water treatment system 1 configured to include: an ammonia treatment system 100 provided with a control unit for adjusting the ammonia concentration of water 2 being treated and a discharge unit 40 for discharging some of the water 2 being treated for which the ammonia concentration has been adjusted; and a reuse system provided with an ammonia addition unit 202 into which flows water 3 to be reused that has not been discharged by the discharge unit 40 and which adds an ammonia compound to the inflowing water 4 being reused, a reaction substance introduction unit 203 for adding, to the inflowing water to be reused 4, a reaction substance that produces a sterilization substance due to a reaction with the ammonia compound and the ammonia remaining in the water 4 to be reused, and a filter unit 204 with which biofouling caused by the sterilization substance included in the water to be reused is suppressed and in which the water 4 to be reused is reused.

Description

Water treatment system and water treatment method

[0001] The present invention relates to a water treatment system and a water treatment method.

[0002] INCORPORATION BY REFERENCE This application claims priority to Japanese Patent Application No. 2023-200861, filed November 28, 2023, the contents of which are incorporated herein by reference. Treatment of contaminated water, such as sewage, is extremely important for improving local public health. A typical method for treating contaminated water is nitrification, which uses a biological treatment process, such as activated sludge, to nitrify ammonia nitrogen.

[0003] On the other hand, there is a technology (reuse technology) that uses seawater, sewage, industrial wastewater, etc. as raw water and treats the raw water to remove salt and trace contaminants, thereby producing reclaimed water that can be reused for drinking, etc. For example, membrane treatment can cause the proliferation of microorganisms, which can clog the raw water flow path and significantly reduce the performance of the device, making it necessary to take measures against biofouling.

[0004] As a technique for cleaning membranes, for example, Patent Document 1 describes a technique in which a high-concentration sodium hypochlorite solution stored in a chemical tank is diluted with membrane-treated water to chemically clean a separation membrane, and a monitoring device monitors the ammoniacal nitrogen concentration in the membrane-treated water, and a control device uses the concentration as an index to control a chemical injection pump and adjust the dilution ratio, thereby maintaining a constant concentration of sodium hypochlorite in the backwash water even if the water quality of the membrane-treated water fluctuates, thereby preventing fluctuations in the chemical cleaning effect.

[0005] Japanese Patent Application Laid-Open No. 2007-275870

[0006] However, such water treatment often involves high costs. For example, in nitrification treatment, aeration is required to maintain the metabolic activity of microorganisms and adjust the ammonia concentration, resulting in very high electricity costs. On the other hand, in membrane treatment for reuse, biofouling inhibitors such as DBNPA (2,2-dibromo-3-nitrilopropionamide) are used as agents that do not cause membrane degradation, but they are expensive and have limitations on their use in drinking water applications. For example, as described in Patent Document 1, biofouling inhibition using combined chlorine such as chloramine is known and used.

[0007] The present invention has been made in consideration of such problems, and aims to provide a water treatment system and a water treatment method that can reduce both the burden associated with the nitrification treatment of the water to be treated and the burden associated with the reuse of the treated water.

[0008] One aspect of the present invention for solving the above problems is an ammonia treatment system comprising: an ammonia treatment system including a control unit that adjusts the ammonia concentration of water to be treated; and a release unit that releases a portion of the water to be treated whose ammonia concentration has been adjusted; an ammonia addition unit that receives water to be reused, which is water to be treated whose ammonia concentration has been adjusted but not released by the release unit, and adds a predetermined ammonia compound to the inflowing water to be reused; a reactant introduction unit that adds a reactant that reacts with the ammonia compound and the ammonia remaining in the water to be reused to the inflowing water to be reused, and a filter unit that reuses the water to be reused and suppresses biofouling by the bactericidal substance contained in the water to be reused.

[0009] According to the present invention, it is possible to reduce both the burden associated with the nitrification treatment of the target water and the burden associated with the reuse of the target treated water. Other configurations and effects will become clear from the description of the following embodiments.

[0010] It is a diagram showing an example of the configuration of a water treatment system 1 according to the present embodiment. It is a flow diagram illustrating an example of a water treatment system control process according to the present embodiment.

[0011] An embodiment of the present invention will be described with reference to the drawings.

[0012] 1 is a diagram showing an example of the configuration of a water treatment system 1 according to this embodiment. The water treatment system 1 includes an ammonia treatment system 100 including one or more aerobic tanks 10, a programmable logic controller (PLC) 20, a blower 30, and a releaser 40, a reuse system 200, and an information processing device 300.

[0013] The PLC 20 and the information processing device 300, and the PLC 20 and the blower unit 30 are communicatively connected via wired or wireless communication networks 50, 51, such as the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), a VPN (Virtual Private Network), or a dedicated line.

[0014] The ammonia treatment system 100 is a nitrification treatment system that reduces the ammonia concentration (ammonia nitrogen concentration; the same applies below) to a target concentration (e.g., 2 to 3 mg / L) by nitrifying water (treatment target water 2), such as sewage, which contains contaminants such as organic matter or ammonia nitrogen and is introduced at a predetermined flow rate into each aerobic tank 10 (10A-10C). The treatment target water 2 with the reduced ammonia concentration (ammonia residual water) is introduced into the reuse system 200.

[0015] Each aerobic tank 10 is provided with a DO meter 11 and a pH meter 12. The DO meter 11 and the pH meter 12 measure the dissolved oxygen (DO) concentration and pH, respectively, of the water to be treated 2 in the aerobic tank 10. Furthermore, one aerobic tank 10A of each aerobic tank 10 is provided with an ammonia meter 13. The ammonia meter 13 is a measuring unit that measures the ammonia concentration of the water to be treated 2 in the aerobic tank 10A. Each aerobic tank 10 is also provided with concentration meters (not shown) that measure the concentrations of various substances such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen, ammonia nitrogen, and total phosphorus.

[0016] The air blower 30 includes, for example, a blower, and performs aeration by sending oxygen-containing air 31 into each aerobic tank 10. This promotes nitrification by microorganisms contained in the water 2 to be treated.

[0017] The amount of air sent by the air blower 30 is controlled by a control signal 52 from the PLC 20, which is the control unit. The PLC 20 controls the airflow so that the ammonia concentration of the water to be treated 2 in each aerobic tank 10 reaches a preset target concentration based on the amount of water to be treated 2 introduced (inflow) into each aerobic tank 10, the amount of water to be treated 2 outflowing from each aerobic tank 10, and the water quality (ammonia concentration, dissolved oxygen concentration, pH, etc.) of each aerobic tank 10. The inflow and outflow amounts of the water to be treated 2 are measured by a flow meter (not shown) or the like.

[0018] At this time, the PLC 20 adjusts the ammonia concentration in each aerobic tank 10 by estimating the current ammonia concentration in the aerobic tanks 10B and 10C based on a predetermined relational expression between the measurement value of the ammonia meter 13 in the aerobic tank 10A and the measurement values ​​of the DO meter 11 and the pH meter 12.

[0019] In the ammonia treatment system 100, an ammonia meter may be provided for each aerobic tank 10. This makes it possible to identify the ammonia concentration in each aerobic tank 10 without using the above relational expression.

[0020] Furthermore, the ammonia concentration in ammonia treatment system 100 may be adjusted by controlling the air volume as described herein, or by controlling other physical or chemical characteristics such as the dissolved oxygen concentration. For example, the dissolved oxygen concentration may be changed while the air volume is controlled to be constant.

[0021] Control (air volume control such as aeration) in such an ammonia treatment system 100 generally requires a high burden (in terms of cost or energy), but as will be described later, the water treatment system 1 of this embodiment is a treatment system that can reduce such a burden.

[0022] Next, the water to be treated 2 whose ammonia concentration has been adjusted by each aerobic tank 10 flows through a pipeline 32, and a predetermined proportion (hereinafter referred to as the regeneration proportion) is introduced into the reuse system 200. Meanwhile, the remaining water to be treated 2 is introduced into a discharge section 40.

[0023] The release section 40 is a pipeline through which the remainder of the ammonia residual water (discharge water 3) flows. A sterilizing substance introduction section 41 is provided at a predetermined position in the release section 40. The sterilizing substance introduction section 41 sterilizes the sterilizing substance 3 flowing through the release section 40 by introducing a predetermined substance (sodium hypochlorite) into the release section 40. A control device (not shown) is provided in the sterilizing substance introduction section 41, which can adjust the amount of the substance introduced.

[0024] A predetermined upper limit (hereinafter referred to as the effluent regulation value) is set for the ammonia concentration in the effluent 3 discharged from the discharge section 40. The ammonia concentration in the effluent 3 is required to be equal to or lower than this effluent regulation value.

[0025] The discharge section 40 may be provided for each series of aerobic tanks 10 or may be provided for a pipeline that collects the water to be treated 2 from each aerobic tank 10 .

[0026] The above-described ammonia treatment system 100 is realized by, for example, at least one of a conventional activated sludge process, a carrier activated sludge process, a membrane separation activated sludge process, and a batch activated sludge process.

[0027] Next, the reuse system 200 is a treatment system that reuses the target treated water (reuse target water 4) from the ammonia treatment system 100 to produce reclaimed water (product water 5). The product water 5 is sent to a predetermined facility and used for purposes such as drinking.

[0028] The recycling system 200 includes a main passage 201 , an ammonia addition section 202 , a reactant introduction section 203 , a recycling device 205 including a filter section 204 , and a branch section 206 .

[0029] The main passage 201 is a pipe through which the water to be reused 4 flows.

[0030] An ammonia addition unit 202 is provided at a predetermined position in the main passage 201. The ammonia addition unit 202 introduces a predetermined ammonia compound into the main passage 201, thereby increasing the ammonia concentration in the reuse water 4 flowing through the main passage 201. The ammonia addition unit 202 is provided with a control device (not shown), which can adjust the amount of ammonia compound introduced. The increase in ammonia concentration promotes the production of a sterilizing substance, which will be described below.

[0031] However, procuring ammonia compounds usually requires a greater burden (cost, work, etc.) than procuring the disinfectant sodium hypochlorite.

[0032] The ammonia compound is, for example, an ammonium salt having ammoniacal nitrogen, such as ammonium sulfate or ammonium chloride. In this embodiment, the ammonia compound is ammonium sulfate.

[0033] A reactant introduction section 203 is provided at a predetermined position in the main passage 201 downstream of the ammonia addition section 202. The reactant introduction section 203 introduces a predetermined reactant into the main passage 201, causing it to react with ammonia in the reuse water 4 flowing through the main passage 201 and produce a predetermined sterilizing substance. The reactant introduction section 203 is provided with a control device (not shown) that can adjust the amount of the reactant introduced.

[0034] The reactant is, for example, a chlorine compound (liquid containing free chlorine) such as sodium hypochlorite, and the free chlorine in the chlorine compound reacts with the ammonia compound or the ammonia nitrogen in the reuse water 4 to produce a sterilizing substance. In this embodiment, the reactant is sodium hypochlorite.

[0035] The bactericidal substance is a bactericide or oxidant containing a bonded halogen as a main component, such as chloramine (chloroamine). This bactericidal substance is a compound produced by reacting with the ammonia compound or the ammoniacal nitrogen in the reuse water 4, and is a nitrogen compound in which some of the hydrogen atoms on the ammonia compound are replaced with chlorine atoms. In this embodiment, the bactericidal substance is chloramine.

[0036] The order of the ammonia adding section 202 and the reactant introducing section 203 may be reversed.

[0037] Furthermore, a recycling device 205 is provided at a predetermined position in the main passage 201 downstream of the reactant introduction section 203. The recycling device 205 includes a filter section 204. The filter section 204 includes, for example, a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), and a reverse osmosis membrane (RO membrane). The reverse osmosis membrane is made of, for example, polyamide. The reverse osmosis membrane suppresses biofouling by removing salt and trace amounts of contaminants contained in the reuse water 4.

[0038] The reuse device 205 then sends a portion of the reuse water 4 from which contaminants and the like have been removed to a predetermined facility as product water 5. Meanwhile, the other portion (brine) of the reuse water 4 from which contaminants and the like have been removed is sent to the discharge section 40 through a branch section 206 connected to the discharge section 40, and is sterilized by the sterilizing substance introduction section 41.

[0039] Here, the filter section 204 may become clogged with microorganisms and the like in the water to be reused 4, which may reduce the reuse performance of the reuse device 205. However, even in such a case, the bactericidal action of the bactericidal substance generated based on the reactant introduction section 203 and the like decomposes the substance that causes clogging in the filter section 204, thereby preventing clogging of the filter section 204.

[0040] The reactions in the ammonia treatment system 100 and the reuse system 200 described above are carried out, for example, at room temperature and atmospheric pressure.

[0041] Next, the information processing device 300 includes a control device (arithmetic device) such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a GPU (Graphics Processing Unit), an FPGA (Field-Programmable Gate Array), or an ASIC (Application Specific Integrated Circuit), a storage device such as a RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), or an SSD (Solid State Drive), a communication device configured with a NIC (Network Interface Card), a wireless communication module, a USB (Universal Serial Interface) module, or a serial communication module, an input device such as a keyboard, a mouse, or a touch panel, and an output device such as a liquid crystal monitor or LCD (Liquid Crystal Display).

[0042] The information processing device 300 has the following functions (programs).

[0043] First, the information processing device 300 stores the upper limit value (discharge water regulation value) of the ammonia concentration of the treatment target water 2 that can be released from the release unit 40 .

[0044] Furthermore, the information processing device 300 calculates the burden (hereinafter referred to as the first burden) imposed on the ammonia treatment system 100 by control by the PLC 20 based on the ammonia concentration of the treatment target water 2 measured by the ammonia meter 13 .

[0045] In addition, the information processing device 300 calculates the burden (hereinafter referred to as the second burden) imposed on the reuse system 200 by the addition of an ammonia compound (ammonium sulfate) and a reactive substance (sodium hypochlorite) to produce a bactericidal substance (chloramine).

[0046] Then, the information processing device 300 calculates the target concentration of ammonia based on the first burden amount and the second burden amount, and controls the PLC 20 so that the ammonia concentration of the water to be treated 2 in the ammonia treatment system 100 becomes the calculated target concentration.

[0047] Specifically, based on the first burden amount and the second burden amount, the information processing device 300 determines whether or not reducing the burden on the ammonia treatment system 100 should be given priority over reducing the burden on the reuse system 200, and if it determines that reducing the burden on the ammonia treatment system 100 should be given priority over reducing the burden on the reuse system 200, it sets the upper limit value (discharge water regulation value) of the ammonia concentration to the target concentration, and controls the PLC 20 so that the ammonia concentration of the water to be treated 2 in the ammonia treatment system 100 becomes the set target concentration.

[0048] On the other hand, when the information processing device 300 determines that reducing the burden on the ammonia treatment system 100 should not be prioritized over reducing the burden on the reuse system 200, it determines whether the upper limit value (effluent water regulation value) exceeds a predetermined threshold, and if the upper limit value exceeds the predetermined threshold, it calculates the ammonia concentration of the water to be treated 2 that should be achieved in the ammonia treatment system 100 to produce the bactericidal substance (chloramine), sets the calculated ammonia concentration to a target concentration, and controls the PLC 20 so that the ammonia concentration of the water to be treated 2 in the ammonia treatment system 100 becomes the set target concentration. On the other hand, when the information processing device 300 determines that the upper limit value does not exceed the predetermined threshold, it sets the upper limit value to the target concentration, and controls the PLC 20 so that the ammonia concentration of the water to be treated 2 in the ammonia treatment system 100 becomes the set target concentration.

[0049] Each function of the information processing device 300 described above is realized by the control device reading and executing each program stored in the storage device. Furthermore, each program can be recorded on a recording medium and distributed, for example. Note that all or part of the information processing device 300 may be realized using virtual information processing resources provided using virtualization technology, process space separation technology, or the like, such as a virtual server provided by a cloud system. Furthermore, all or part of the functions provided by the information processing device 300 may be realized by a service provided by the cloud system via an API (Application Programming Interface), for example.

[0050] The information processing device may be configured to control each device in the ammonia treatment system 100 and the reuse system 200. Next, the control performed in the water treatment system 1 will be described.

[0051] 2 is a flow diagram illustrating an example of a control process (water treatment system control process) of the water treatment system 1 according to this embodiment. The water treatment system control process is repeatedly executed, for example, at a predetermined timing (for example, a predetermined time or a predetermined time interval) or when a predetermined input is made to the information processing device 300.

[0052] First, the information processing device 300 calculates a load (first load) that is imposed on the ammonia treatment system 100 due to the air volume control by the PLC 20 (s11).

[0053] For example, first, the information processing device 300 acquires information on the target ammonia concentration in the reuse water 4 discharged from the aerobic tank 10. The information processing device 300 also acquires the current ammonia concentration in the reuse water 4 from the ammonia meter 13. The information processing device 300 also acquires the inflow amount of the treatment water 2 into the aerobic tank 10 and the outflow amount of the treatment water 2 from the aerobic tank 10 using a flow meter. The information processing device 300 also acquires the concentrations of various substances in the treatment water 2 in the aerobic tank 10 using each concentration meter. The inflow and outflow amounts may be acquired from actual values ​​from past operations of the water treatment system.

[0054] Based on the acquired information, the information processing device 300 then calculates the amount of oxygen required to achieve and maintain the target ammonia concentration in each aerobic tank 10, calculates the airflow rate of the blower 30 according to the calculated amount of oxygen required, and calculates the amount of electricity required to operate the blower 30 and the electricity fee. When calculating the amount of oxygen required, the amounts of oxygen required for BOD oxidation, nitrification, endogenous respiration, and DO maintenance are calculated as the amounts of oxygen required for biological treatment. The methods for deriving each item are disclosed, for example, in "Sewerage Facility Planning and Design Guidelines and Commentary" (Japan Sewage Works Association, 2019).

[0055] The information processing device 300 may also take into account other costs in the ammonia treatment system 100 (for example, the operating costs of the pump that adjusts the flow rate of the treatment target water 2, or the operating costs of the blower unit 30) in the burden.

[0056] Next, the information processing device 300 acquires information on the regeneration ratio (s12). For example, the information processing device 300 may read pre-stored information on the regeneration ratio, may accept input of the regeneration ratio from an administrator, or may acquire the information on the regeneration ratio from the reuse system 200. The information processing device 300 may also calculate the regeneration ratio based on the outflow amount of the water to be treated 2 from the ammonia treatment system 100, the amount of the water to be reused 4 flowing into the reuse device 205, or the amount of the discharged water 3 flowing into the release section 40.

[0057] Furthermore, the information processing device 300 identifies the concentration of chloramine required to suppress biofouling in the filter section 204, and calculates the burden (second burden) imposed on the reuse system 200 by the introduction of ammonium sulfate by the ammonia addition section 202 and / or the introduction of sodium hypochlorite by the reactant introduction section 203, which are required to produce chloramine at that concentration (s13).

[0058] For example, first, the information processing device 300 sets an arbitrary value less than 4 mg / L as the chloramine concentration necessary to suppress biofouling, which is a concentration that does not deteriorate the filter unit 204 .

[0059] The information processing device 300 then calculates the amount (or concentration) of sodium hypochlorite (from the reactant introduction unit 203) and the total amount (or concentration) of ammonia (the sum of the amount of ammonia in the reuse water 4 introduced into the reuse system 200 and the amount of ammonium sulfate introduced from the ammonia addition unit 202) required to produce chloramines at this concentration based on the stoichiometric ratio indicated by the chemical reaction formula for chloramine production.The information processing device 300 then calculates the amount of ammonium sulfate to be introduced from the ammonia addition unit 202 and the cost of ammonium sulfate for that amount by subtracting the amount of ammonia in the reuse water 4 calculated from the regeneration ratio calculated in s12 from the calculated total amount of ammonia.

[0060] In addition, the information processing device 300 may also take other costs in the reuse system 200 (for example, the operating costs of the pump that adjusts the flow rate of the reuse water 4, the operating costs of the ammonia addition section 202, or the operating costs of the reactant introduction section 203) into account when calculating the burden.

[0061] The information processing device 300 creates a judgment formula for determining whether reducing the burden on the ammonia processing system 100 should be prioritized over reducing the burden on the reuse system 200, based on the first burden calculated in s11 and the second burden calculated in s13 (s14).

[0062] For example, the information processing device 300 calculates the value of {(the second burden amount calculated in s13)} / ((the second burden amount calculated in s13)+(the first burden amount calculated in s11)}. In addition, the information processing device 300 sets the playback ratio calculated in s12 as a threshold value.

[0063] Based on the determination formula created in s14, the information processing device 300 determines (s15) whether or not reducing the load on the ammonia processing system 100 should be prioritized over reducing the load on the reuse system 200. For example, the information processing device 300 determines whether or not the value calculated in s14 is smaller than the threshold value set in s14.

[0064] If reducing the burden on the ammonia processing system 100 should be given priority over reducing the burden on the reuse system 200 (s15: YES), the information processing device 300 executes the process of s16, and if reducing the burden on the ammonia processing system 100 should not be given priority over reducing the burden on the reuse system 200 (s15: NO), the information processing device 300 executes the process of s18.

[0065] In s16, the information processing device 300 calculates a target concentration for each aerobic tank 10 of the ammonia treatment system 100 so that the ammonia concentration in the effluent 3 becomes the effluent regulation value. The effluent regulation value is, for example, 1 mg / L or 4 mg / L.

[0066] For example, the information processing device 300 calculates the ammonia concentration that should be achieved in the water to be treated 2 in each aerobic tank 10 of the ammonia treatment system 100 based on the discharge water regulation value, the regeneration rate, the outflow amount of the water to be treated 2 from the ammonia treatment system 100, etc.

[0067] Then, the information processing device 300 controls the air blowing by the air blowing unit 30 based on the calculated target concentration (s17).

[0068] For example, the information processing device 300 transmits the concentration calculated in s16 as the target concentration to the PLC 20. The PLC 20 controls the blower 30 so that the ammonia concentration in the treatment target water 2 in each aerobic tank 10 reaches and maintains the target concentration.

[0069] In addition, during the control of s17, if chloramines are not produced in the reuse system 200 at a predetermined concentration (e.g., 2 to 3 mg / L) or more, the ammonia addition unit 202 may introduce an ammonium compound into the main passage 201 to produce chloramines at a predetermined concentration or more.

[0070] By controlling the ammonia concentration in s16 and s17, the burden on the ammonia treatment system 100 (particularly, the electricity charges related to the air volume control) can be reduced.

[0071] On the other hand, in s18, the information processing device 300 determines whether the discharge water regulation value exceeds a predetermined concentration (for example, 1 mg / L).

[0072] If the discharge water regulation value exceeds the predetermined concentration (s18: YES), the information processing device 300 executes processing of s19, and if the discharge water regulation value does not exceed the predetermined concentration (s18: NO), the information processing device 300 executes processing of s21.

[0073] In step S19, the information processing device 300 calculates the ammonia concentration of the water to be treated 2 that must be achieved in the ammonia treatment system 100 in order to produce chloramine at a predetermined concentration or higher (e.g., 2 to 3 mg / L), and sets the calculated ammonia concentration as the target concentration.

[0074] For example, the information processing device 300 calculates the amount of ammonia required to produce a desired concentration of chloramine based on the stoichiometric ratio indicated by the chemical reaction formula for chloramine production. Then, the information processing device 300 calculates the ammonia concentration of the treatment target water 2 in each aerobic tank 10 based on the regeneration ratio and the like so that the calculated amount of ammonia can be flowed from the ammonia treatment system 100 into the reuse system 200, and sets the calculated concentration as the target concentration.

[0075] Then, the information processing device 300 controls the air blowing by the air blowing unit 30 based on the calculated target concentration (s20).

[0076] For example, the information processing device 300 transmits the target concentration calculated in s19 to the PLC 20. The PLC 20 controls the blower 30 so that the ammonia concentration in the treatment target water 2 in each aerobic tank 10 reaches and maintains the target concentration.

[0077] According to this process, the addition of ammonia by the ammonia addition unit 202 is basically unnecessary. However, if chloramines are not generated in the reuse system 200 at a predetermined concentration (e.g., 2 to 3 mg / L) or more, the ammonia addition unit 202 may introduce an ammonium compound into the main passage 201 to generate chloramines at a predetermined concentration or more.

[0078] By controlling the ammonia concentration in steps s19 and s20, the load on the reuse system 200 (particularly, the addition of ammonium sulfate by the ammonia adding unit 202) can be reduced.

[0079] In s21, the information processing device 300 calculates the target concentration for each aerobic tank 10 of the ammonia treatment system 100 so that the ammonia concentration in the effluent 3 becomes the effluent regulation value, similarly to s16.

[0080] Then, similar to s17, the information processing device 300 controls the air blowing by the air blowing unit 30 based on the calculated target concentration (s22).

[0081] By controlling the ammonia concentration in s21 and s22, the burden on the reuse system 200 (particularly, the addition of sodium hypochlorite by the reactant introduction section 203) can be reduced.

[0082] As described above, the water treatment system 1 of this embodiment is configured to include an ammonia addition section 202 into which the reuse target water 4 flows and which adds a predetermined ammonia compound (ammonium sulfate, etc.) to the inflowing reuse target water 4, a reactant introduction section 203 which adds a reactant (sodium hypochlorite, etc.) to the inflowing reuse target water 4, which reacts with the ammonia compound and the ammonia remaining in the reuse target water 4 to produce a predetermined bactericidal substance (chloramine, etc.), and a reuse system 200 which reuses the reuse target water 4 and is equipped with a filter section 204 in which biofouling is suppressed by the bactericidal substance contained in the reuse target water 4.

[0083] That is, the water treatment system 1 of this embodiment produces a bactericidal substance by reacting the reuse target water 4 from the ammonia treatment system 100 with the ammonia compound from the ammonia addition section 202 and the reactant from the reactant introduction section 203, thereby suppressing biofouling in the filter section 204 that reuses the reuse target water 4.

[0084] This allows the ammonia remaining in the ammonia treatment system 100 to be used to maintain or improve the performance of the regeneration treatment of the reuse-target water 4 in the reuse system 200, thereby reducing the burden (such as the cost of ammonia compounds) associated with reuse in the reuse system 200. Furthermore, the amount of ammonia concentration adjustment (amount of reduction) performed in the ammonia treatment system 100 can be reduced by the amount used to maintain or improve the performance of the regeneration treatment, thereby reducing the burden (such as costs) associated with the ammonia treatment in the ammonia treatment system 100.

[0085] As described above, the water treatment system 1 of this embodiment can reduce both the burden associated with the nitrification treatment of the target water 2 and the burden associated with the reuse of the target treated water. For example, the operating expense (OPEX) in the ammonia treatment can be improved.

[0086] In addition, the information processing device 300 of the water treatment system 1 of this embodiment calculates the target concentration of ammonia in the ammonia treatment system 100 based on the burden on the ammonia treatment system 100 caused by the adjustment and control of the ammonia concentration by the PLC 20 and the burden on the reuse system 200 caused by the production of the bactericidal substance (the burden related to the suppression of biofouling), and controls the PLC 20 so that the ammonia concentration of the water to be treated 2 becomes the target concentration.

[0087] This makes it possible to control the ammonia concentration and perform reclamation treatment of the target water 2 at an appropriate balance taking into consideration the load on the ammonia treatment system 100 and the load on the reuse system 200. This also makes it possible to optimize the combined control of sewage treatment and reclamation treatment.

[0088] In addition, the information processing device 300 of the water treatment system 1 of this embodiment controls the ammonia concentration to target the upper limit value of the ammonia concentration in the ammonia treatment system 100 when reducing the burden (cost, etc.) on the ammonia treatment system 100 should be given priority over the burden (cost, etc.) on the reuse system 200.

[0089] This minimizes the need to control the ammonia concentration, thereby reducing the burden (costs, etc.) on the ammonia treatment system 100 .

[0090] Furthermore, in the case where reducing the burden on the reuse system 200 should be prioritized over reducing the burden on the ammonia treatment system 100, if the upper limit value of the ammonia concentration in the ammonia treatment system 100 is high, the information processing device 300 of the water treatment system 1 of this embodiment controls the PLC 20 by setting the ammonia concentration in the treatment target water 2 to be achieved by the ammonia treatment system 100 to a target concentration based on the amount of ammonia compound required to produce the sterilizing substance, whereas if the upper limit value of the ammonia concentration is not high, the information processing device 300 sets the upper limit value to the target concentration and controls the PLC 20.

[0091] In this way, when the upper limit of the ammonia concentration in the ammonia treatment system 100 is high, control is performed to maintain the ammonia concentration required to produce the sterilizing substance, thereby efficiently improving the reuse performance of the reuse system 200 and reducing its burden. On the other hand, when the upper limit of the ammonia concentration in the ammonia treatment system 100 is low, improvement in reuse performance is unlikely, so the burden on the ammonia treatment system 100 can be reduced by performing control in which the release upper limit is set to the target concentration. In this way, a well-balanced reduction in the burden on the ammonia treatment system 100 and the reuse system 200 can be achieved depending on the upper limit of the ammonia concentration in the ammonia treatment system 100. In this case, there is no need to adjust the concentration of the reactant in order to set the target ammonia concentration in the water to be treated 2.

[0092] In addition, when the upper limit value of the ammonia concentration exceeds a predetermined threshold, the information processing device 300 of the water treatment system 1 of this embodiment calculates a target ammonia concentration required to produce a sterilizing substance of a predetermined concentration.

[0093] This makes it possible to reliably suppress biofouling of the filter section 204 .

[0094] Specifically, the information processing device 300 of the water treatment system 1 of this embodiment calculates the target ammonia concentration required to produce a sterilizing substance with a concentration of less than 4 mg / L.

[0095] This makes it possible to reliably suppress biofouling of the filter section 204 while preventing deterioration of the filter section 204 .

[0096] Furthermore, the PLC 20 of the water treatment system 1 of this embodiment controls the air volume to adjust the ammonia concentration and the dissolved oxygen concentration of the water 2 to be treated.

[0097] This allows the ammonia concentration to be adjusted to a desired concentration.

[0098] In addition, the ammonia treatment system 100 of the water treatment system 1 of this embodiment adjusts the ammonia concentration of the water to be treated 2 by at least one of the following methods: a standard activated sludge process, a carrier sludge process, a membrane separation activated sludge process, or a batch activated sludge process.

[0099] This allows the ammonia concentration to be reliably adjusted.

[0100] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be implemented using any components within the scope of the gist of the present invention. The above-described embodiments and modifications are merely examples, and the present invention is not limited to these contents as long as the characteristics of the invention are not impaired. Furthermore, although various embodiments and modifications have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of ​​the present invention are also included within the scope of the present invention.

[0101] Furthermore, part of the hardware provided in each device of this embodiment may be provided in another device.

[0102] Furthermore, each program of each device may be provided in another device, a program may consist of multiple programs, or multiple programs may be integrated into one program.

[0103] Furthermore, in this embodiment, a fee (cost) is calculated as the burden, but other parameters that represent the burden (for example, energy consumption, greenhouse gas emissions) may also be calculated. The aeration air volume is an item related to energy consumption, and the greenhouse gas emissions are calculated from the CO2 emissions due to electricity use and the CO2 emissions due to chemical use. The burden may also be a comprehensive evaluation of the energy reduction effect and the greenhouse gas reduction effect.

[0104] Furthermore, the determination formula described in this embodiment is merely an example, and any formula can be used to compare the priorities of reducing the load on the ammonia treatment system 100 and reducing the load on the reuse system 200.

[0105] 1 Water treatment system, 10 Aerobic tank, 20 PLC, 30 Blowout section, 200 Reuse system, 202 Ammonia addition section, 203 Reactant introduction section, 204 Filter section

Claims

1. An ammonia treatment system comprising: a control unit that adjusts the ammonia concentration of the water to be treated, and a release unit that releases a portion of the water to be treated whose ammonia concentration has been adjusted; an ammonia addition unit that receives water to be reused, which is the water to be treated whose ammonia concentration has been adjusted and that has not been released by the release unit, and adds a predetermined ammonia compound to the inflowing water to be reused; a reactant introduction unit that adds a reactant that reacts with the ammonia compound and the ammonia remaining in the water to be reused to produce a predetermined bactericidal substance, to the inflowing water to be reused; and a reuse system that reuses the water to be reused, and has a filter unit in which biofouling is suppressed by the bactericidal substance contained in the water to be reused.

2. The water treatment system according to claim 1, further comprising an information processing device, wherein the ammonia treatment system comprises a control unit that performs control to adjust the ammonia concentration of the water to be treated to a target concentration, and a measurement unit that measures the ammonia concentration of the water to be treated, and the information processing device comprises: a storage device that stores an upper limit value of the ammonia concentration of the water to be treated that can be released from the release unit, and a control device that calculates a first burden amount that is a burden amount placed on the ammonia treatment system by control by the control unit based on the ammonia concentration of the water to be treated measured by the measurement unit, calculates a second burden amount that is a burden amount placed on the reuse system by the addition of the ammonia compound and the reactant performed to produce the bactericidal substance, calculates the target concentration based on the first burden amount and the second burden amount, and controls the control unit so that the ammonia concentration of the water to be treated in the ammonia treatment system becomes the calculated target concentration.

3. The water treatment system described in claim 2, wherein the information processing device includes a storage device which stores an upper limit value of the ammonia concentration of the water to be treated that can be released from the release unit, and determines whether or not reducing the burden on the ammonia treatment system should be prioritized over reducing the burden on the reuse system based on the first burden amount and the second burden amount, and if it is determined that reducing the burden on the ammonia treatment system should be prioritized over reducing the burden on the reuse system, sets the upper limit value to the target concentration, and controls the control unit so that the ammonia concentration of the water to be treated in the ammonia treatment system becomes the set target concentration.

4. The water treatment system according to claim 2, wherein the information processing device is further provided with a storage device which stores an upper limit value of an ammonia concentration of the target water that can be released from the release unit; and determines whether or not reducing the burden on the ammonia treatment system should be given priority over reducing the burden on the reuse system based on the first burden amount and the second burden amount, and if it is determined that reducing the burden on the ammonia treatment system should not be given priority over reducing the burden on the reuse system, determines whether or not the upper limit value exceeds a predetermined threshold value; if the upper limit value exceeds the predetermined threshold value, calculates an ammonia concentration of the target water to be achieved in the ammonia treatment system which is necessary for producing the bactericidal substance, sets the calculated ammonia concentration to the target concentration, and controls the control unit so that the ammonia concentration of the target water in the ammonia treatment system becomes the set target concentration; and if the upper limit value does not exceed the predetermined threshold value, sets the upper limit value to the target concentration, and controls the control unit so that the ammonia concentration of the target water in the ammonia treatment system becomes the set target concentration.

5. The water treatment system of claim 4, wherein the information processing device calculates the ammonia concentration of the water to be treated that is required to produce a predetermined concentration of the bactericidal substance when the upper limit value exceeds a predetermined threshold value.

6. The water treatment system of claim 5, wherein the information processing device calculates the ammonia concentration of the water to be treated that is required to produce a concentration of the bactericidal substance of less than 4 mg / L when the upper limit value exceeds a predetermined threshold value.

7. The water treatment system according to claim 1, wherein the control unit controls the air volume to adjust the ammonia concentration and the dissolved oxygen concentration of the water to be treated.

8. The water treatment system according to claim 1, wherein the ammonia concentration of the water to be treated is adjusted by at least one of a standard activated sludge process, a carrier sludge process, a membrane separation activated sludge process, and a batch activated sludge process.

9. A water treatment method comprising: providing an ammonia treatment system having a control unit which adjusts the ammonia concentration of the water to be treated, and a release unit which releases a portion of the water to be treated whose ammonia concentration has been adjusted; an ammonia addition unit which receives water to be reused, which is water to be treated whose ammonia concentration has been adjusted and which does not get released by the release unit, and which adds a predetermined ammonia compound to the inflowing water to be reused; a reactant introduction unit which adds a reactant which reacts with the ammonia compound and the ammonia remaining in the water to be reused to produce a predetermined bactericidal substance, to the inflowing water to be reused; and a reuse system which reuses the water to be reused and has a filter unit in which biofouling is suppressed by the bactericidal substance contained in the water to be reused.

10. The water treatment method according to claim 9, further comprising an information processing device, wherein the ammonia treatment system is provided with a control unit that controls the ammonia concentration of the target water to be treated to be adjusted to a target concentration, and a measurement unit that measures the ammonia concentration of the target water to be treated, wherein the information processing device: stores an upper limit value of the ammonia concentration of the target water to be treated that can be released from the release unit; calculates a first burden amount that is a burden amount placed on the ammonia treatment system by control by the control unit based on the ammonia concentration of the target water to be treated measured by the measurement unit; calculates a second burden amount that is a burden amount placed on the reuse system by addition of the ammonia compound and the reactant performed to produce the bactericidal substance; calculates the target concentration based on the first burden amount and the second burden amount, and controls the control unit so that the ammonia concentration of the target water to be treated in the ammonia treatment system becomes the calculated target concentration.

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