A method for harmless treatment and resource recovery of swimming pool water

Abstract

A method for harmless treatment and resource recovery of swimming pool water. The swimming pool water sequentially enters a first reaction tank, a second reaction tank, a sedimentation tank, a third reaction tank, a cyanuric acid recovery tank, an electrochemical reactor, a safety filter and a clear water tank for treatment. The method of the present invention is simple, easy to operate, occupies a small area of ​​the project, has low investment, low cost, is convenient for operation and management, is resistant to load impact, reduces labor intensity, saves manpower and recycles wastewater, can save more than 90% of water resources, has no secondary pollution, realizes comprehensive harmless treatment and recovery of pollutants, and has significant economic and social benefits.

Description

Technical Field

[0001] The invention relates to the field of resource recovery of swimming pool water treatment agents, in particular to a method for harmless treatment and resource recovery of swimming pool water. Background Art

[0002] With the improvement of the living standards of Chinese residents, swimming has been widely loved by residents as an entertainment and fitness project, and the safety of swimming pool water quality is directly related to the physical and mental health of users. Traditional swimming pool disinfection can no longer meet people's requirements. Trichloroisocyanuric acid and sodium dichloroisocyanurate are widely used as new chlorine products for swimming pool water disinfection. Cyanurate ions play an important role as a sustained-release agent in the disinfection process of trichloroisocyanuric acid and sodium dichloroisocyanurate, but excessive cyanurate ions will cause a "chlorine lock" phenomenon, resulting in a decrease in the disinfection effect. At the same time, consumers will bring in a lot of sweat, dandruff, urea, etc. during swimming, causing the pool water to become turbid, discolored, and bacteria to grow. In order to solve the problem of swimming pool water pollution, it is often necessary to add a large amount of disinfectants, clarifiers and other chemical reagents to the swimming pool water, which not only seriously affects consumer safety, but also increases the management difficulty and operating costs of swimming pool managers. At the same time, cyanuric acid and NH4 + -N、PO4 3- -P and other substances are indispensable industrial production substrates and are non-renewable resources. Therefore, a treatment method needs to be designed to treat swimming pool water without pollution and to treat excess cyanuric acid and NH4 + -N、PO4 3- -P and other substances can be effectively recycled to achieve harmless and resource-based treatment of swimming pool water, but there has been no relevant public report so far. Summary of the Invention

[0003] In view of the above situation, in order to overcome the defects of the existing technology, the purpose of the present invention is to provide a method for harmless treatment and resource recovery of swimming pool water, which can effectively solve the problem that the existing equipment cannot treat swimming pool water harmlessly and the cyanuric acid in the water is excessive.

[0004] To achieve the above-mentioned purpose, the technical solution provided by the present invention is a method for harmless treatment and resource recovery of swimming pool water, comprising the following steps:

[0005] S1. The swimming pool water enters the first reaction tank. The urease solution in the first reagent tank enters the first reaction tank through the reagent pump. The urea probe monitors the urea concentration in the first reaction tank in real time and feeds back to the PLC controller. When the monitored urea concentration is greater than 0.5 mg / L, the PLC controller controls the first reagent pump to pump the urease in the first reagent tank into the first reaction tank. The reaction lasts for 15-20 minutes. The urease reacts with urea to produce NH4 + -N and carbon dioxide, the effluent enters the second reaction tank;

[0006] S2, NH4 in the second reaction tank + -N and PO4 3- -P probe real-time monitoring of NH4 in the reaction pool + -N、PO4 3- -P concentration and feed it back to the PLC controller, which controls the second reagent pump to pump the MgCl2 solution in the second reagent tank into the reaction tank to react with the urea decomposition product NH4 + -N and NH4 in swimming pool water + -N and PO4 3- -P generates struvite MgNH4PO4·6H2O, controlling Mg:NH4 + :PO4 3- =1:1:1, react for 15-20 minutes, and recover struvite by gravity sedimentation. The mixed solution enters the sedimentation tank and settles in the sedimentation tank for 15-20 minutes. The supernatant enters the third reaction tank;

[0007] S3. The melamine solution in the third reagent tank enters the third reaction tank through the third reagent pump. The melamine solution reacts with cyanurate ions in the water to form melamine cyanurate precipitate. The pH-cyanuric acid probe in the third reaction tank monitors the pH and cyanuric acid concentration in the third reaction tank in real time and feeds back to the PLC controller. When the monitored pH is less than 6.0, the PLC controller controls the fourth reagent pump to pump the alkaline agent in the fourth reagent tank into the third reaction tank, controls the pH in the third reaction tank to 7.0-7.5, reacts for 15-20 minutes, and then pumps the mixed solution into the cyanuric acid recovery tank through the sewage pump;

[0008] S4. After the supernatant enters the cyanuric acid recovery tank, it enters the first filter through the first water inlet valve for filtration to remove cyanurate in the water. The filtered swimming pool water is discharged through the first automatic drain valve. Melamine cyanurate is intercepted on the surface of the filter membrane and gradually forms a filter cake. The gradual thickening of the filter cake will increase the internal and external pressure difference. When the pressure difference between the first external pressure valve and the second internal pressure valve is greater than 100kpa, the PLC controller controls the first water inlet valve to close and opens the second water inlet valve at the same time. The swimming pool water entering the cyanuric acid recovery tank enters the second filter through the second water inlet valve for treatment. When the pressure difference between the second external pressure sensor and the second internal sensor is greater than 100kpa, the PLC controller controls the first water inlet valve to close and opens the second water inlet valve at the same time. The controller controls the second water inlet valve to close and the third water inlet valve to open at the same time. When the pressure difference between the third external pressure sensor and the third internal sensor is greater than 100kPa, the PLC controller controls the third water inlet valve to close and the first water inlet valve to open at the same time. The three filters in the cyanuric acid recovery tank work in sequence. After each filter finishes filtering, it will automatically drain the water and start the motor to drive the filter plate to rotate. The filter cake on the filter membrane is scraped off by the scraper and discharged through the first automatic mud discharge valve into the recovery bag at the bottom of the cyanuric acid recovery tank. The melamine cyanurate in the recovery bag of the cyanuric acid recovery tank is recovered and dehumidified and dried for the production of halogen-free flame retardant. The filtered swimming pool water enters the electrochemical reactor.

[0009] S5. The swimming pool water is removed from the electrochemical reactor to remove chloroform, dichloromonobromomethane, and bromoform disinfection byproducts. At the same time, urea substances in the water are further removed. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the third reaction tank is greater than 100ug / L, the PLC controller starts the DC power supply with a power of 2-3mA / cm 2 For every 10ug / L increase in the total concentration of chloroform, dichloromonobromoform and bromoform in the swimming pool water entering the electrochemical reactor, the DC power supply power increases by 0.5mA / cm 2 For every 10ug / L reduction, the DC power supply power is reduced by 0.5mA / cm 2 , hydraulic retention 15-20 minutes, the treated swimming pool water is pumped into the security filter through the clean water pump;

[0010] S6. The swimming pool water removes fine particles in the security filter and the effluent enters the clean water tank. The urea-cyanuric acid probe monitors the cyanuric acid concentration in the water in the clean water tank in real time and feeds back to the PLC controller. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the sampled monitoring water is greater than 100ug / L, the PLC controller controls the opening of the first reflux pump to return the swimming pool water to the electrochemical reactor for further chloroform, dichloromonobromomethane and bromoform treatment; when the cyanuric acid concentration in the monitored water is greater than 50mg / L, the PLC controller controls the opening of the first reflux pump to return the swimming pool water to the electrochemical reactor for further chloroform, dichloromonobromomethane and bromoform treatment; / L, the PLC controller controls the opening of the second reflux pump to return the swimming pool water to the third reaction tank for re-treatment. At the same time, the PLC controller controls the third chemical pump to increase the dosage of melamine. For every 1 mg / L increase in cyanuric acid concentration, the dosage of melamine increases by 0.7 mg / L. When the urea concentration in the monitored water is not greater than 0.5 mg / L, the cyanuric acid concentration is not greater than 50 mg / L, and the total concentration of chloroform, dichloromonobromomethane and bromoform is not greater than 100 ug / L, the water is returned to the swimming pool for continued use.

[0011] The method of the present invention is simple, easy to operate, occupies a small area of ​​the project, has low investment, low cost, is convenient for operation and management, is resistant to load impact, reduces labor intensity, saves manpower and recycles wastewater, can save more than 90% of water resources, has no secondary pollution, realizes comprehensive harmless treatment and recovery of pollutants, and has significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a structural frame diagram of the present invention.

[0013] Figure 2 It is a schematic diagram of the internal structure of the cyanuric acid recovery tank of the present invention.

[0014] Figure 3 It is a schematic diagram of the installation of the filter membrane and scraper of the present invention. DETAILED DESCRIPTION

[0015] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings and specific circumstances.

[0016] In conjunction with the accompanying drawings, a method for harmless treatment and resource recovery of swimming pool water is provided, comprising the following steps:

[0017] S1, swimming pool water enters the first reaction tank 1, the urease solution in the first reagent box 1-1 enters the first reaction tank 1 through the reagent pump, the urea probe 1-3 monitors the urea concentration in the first reaction tank 1 in real time and feeds it back to the PLC controller 8. When the monitored urea concentration is greater than 0.5 mg / L, the PLC controller 8 controls the first reagent pump 1-4 to pump the urease in the first reagent box 1-1 into the first reaction tank 1. The reaction lasts for 15-20 minutes. The urease reacts with urea to produce NH4 + -N and carbon dioxide, the effluent enters the second reaction tank 2;

[0018] S2, NH4 in the second reaction tank 2 + -N and PO4 3- -P probe 2-3 real-time monitoring of NH4 in reaction pool 2 + -N、PO4 3- -P concentration and feed it back to the PLC controller 8, which controls the second reagent pump 2-4 to pump the MgCl2 solution in the second reagent tank 2-1 into the reaction tank 2 to react with the urea decomposition product NH4 + -N and NH4 in swimming pool water + -N and PO4 3- -P generates struvite MgNH4PO4·6H2O, controlling Mg:NH4 + :PO4 3- =1:1:1, react for 15-20 minutes, and the struvite is recovered by gravity precipitation. The mixed liquid enters the sedimentation tank 3 and settles in the sedimentation tank for 15-20 minutes. The supernatant enters the third reaction tank 4;

[0019] S3, the melamine solution in the third reagent box 4-1 enters the third reaction tank 4 through the third reagent pump 4-6, and the melamine solution reacts with the cyanurate ion in the water to form a melamine cyanurate precipitate. The pH-cyanuric acid 4-5 in the third reaction tank 4 monitors the pH and cyanuric acid concentration in the third reaction tank 4 in real time and feeds back to the PLC controller 8. When the monitored pH is less than 6.0, the PLC controller 8 controls the fourth reagent pump 4-7 to pump the alkaline agent in the fourth reagent box 4-4 into the third reaction tank 4, controls the pH in the third reaction tank 4 to be 7.0-7.5, reacts for 15-20 minutes, and the mixed solution is pumped into the cyanuric acid recovery tank 5 through the sewage pump 4-3;

[0020] S4. After the supernatant enters the cyanuric acid recovery tank 5, it enters the first filter 5-1 through the first water inlet valve 5-4 for filtration to remove cyanurate in the water. The filtered swimming pool water is discharged through the first automatic drain valve 5-13. Melamine cyanurate is intercepted on the surface of the filter membrane and gradually forms a filter cake. The gradual thickening of the filter cake will increase the internal and external pressure difference. When the pressure difference between the first external pressure valve 5-7 and the second internal pressure valve 5-8 is greater than 100kpa, the PLC controller 8 controls the first water inlet valve 5-4 to close and opens the second water inlet valve 5-5 at the same time. The swimming pool water entering the cyanuric acid recovery tank 5 enters the second filter 5-2 for treatment through the second water inlet valve 5-5. When the pressure difference between the second external pressure sensor 5-9 and the second internal sensor 5-10 is greater than 100kpa, the PLC controller 8 controls the first water inlet valve 5-4 to close and opens the second water inlet valve 5-5 at the same time. The controller 8 controls the second water inlet valve 5-5 to close and opens the third water inlet valve 5-6 at the same time. When the pressure difference between the third external pressure sensor 5-11 and the third internal pressure sensor 5-12 is greater than 100 kPa, the PLC controller 8 controls the third water inlet valve 5-6 to close and opens the first water inlet valve 5-4 at the same time. The three filters in the cyanuric acid recovery tank 5 work in sequence. After each filter finishes filtering, it automatically drains the water and starts the motor 5-22 to drive the filter plate to rotate. The filter cake on the filter membrane 503 is scraped off by the scraper 502 and discharged into the recovery bag at the bottom of the cyanuric acid recovery tank 5 through the first automatic mud discharge valve 5-16. The melamine cyanurate in the recovery bag of the cyanuric acid recovery tank 5 is recovered and dehumidified and dried for the production of halogen-free flame retardant. The filtered swimming pool water enters the electrochemical reactor 6.

[0021] S5. The swimming pool water is removed from the electrochemical reactor 6 to remove chloroform, dichloromonobromomethane, and bromoform disinfection byproducts. At the same time, urea and other substances in the water are further removed. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the water of the third reaction tank 4 is greater than 100ug / L, the PLC controller starts the DC power supply 6-2 with a power of 2-3mA / cm 2 For every 10ug / L increase in the total concentration of chloroform, dichloromonobromoform and bromoform in the swimming pool water entering the electrochemical reactor 6, the power of the DC power supply 6-2 increases by 0.5mA / cm 2 For every 10ug / L reduction, the power of DC power supply 6-2 is reduced by 0.5mA / cm 2 , hydraulic retention 15-20min, the treated swimming pool water is pumped into the security filter 7 through the clean water pump 6-3;

[0022] S6. Fine particles are removed from the swimming pool water in the security filter 7, and the effluent enters the clean water tank 9. The urea-cyanuric acid probe 8-1 monitors the cyanuric acid concentration in the water in the clean water tank 9 in real time and feeds back to the PLC controller 8. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the sampled monitoring water is greater than 100ug / L, the PLC controller 8 controls the start of the first reflux pump 8-3 to return the swimming pool water to the electrochemical reactor 6 for further treatment with chloroform, dichloromonobromomethane and bromoform; when the cyanuric acid concentration in the monitored water is greater than 50mg / L, the PLC controller 8 controls the start of the second reflux pump 8-2 to return the swimming pool water to the third reaction tank 4 for re-treatment. At the same time, the PLC controller 8 controls the third chemical pump 4-6 to increase the dosage of melamine. For every 1mg / L increase in the cyanuric acid concentration, the dosage of melamine increases by 0.7mg / L. When the monitored urea concentration in the water is no more than 0.5 mg / L, the cyanuric acid concentration is no more than 50 mg / L, and the total concentration of chloroform, dichlorobromomethane and bromoform is no more than 100 ug / L, it will be returned to the swimming pool for continued use.

[0023] In order to protect the better implementation effect, the cyanuric acid recovery tank 5 is equipped with a first filter assembly, a second filter assembly and a third filter assembly with the same structure in sequence. The first filter assembly includes a first filter 5-1, a first water inlet valve 5-4, a first external pressure valve 5-7, a first internal pressure valve 5-8, a first automatic drain valve 5-13 and a first automatic mud discharge valve 5-16. The second filter assembly includes a second filter 5-2, a second water inlet valve 5-5, a second external pressure valve 5-9, a second internal pressure valve 5-10, a second automatic drain valve 5-14 and a second automatic mud discharge valve 5-17. The third filter assembly includes a third filter 5-3, a third water inlet valve 5-6, a third external pressure valve 5-11, a third internal pressure valve 5-12, a third automatic drain valve 5-15 and a third automatic mud discharge valve 5-18. The first filter 5-1 inlet A first water inlet valve 5-4 is installed on the pipe, a first external pressure valve 5-7 and a first internal pressure valve 5-8 connected to the interior are installed on the first filter 5-1, a first automatic drain valve 5-13 is installed on the filter screen outlet pipe in the first filter 5-1, and a first automatic mud discharge valve 5-16 is installed on the slag discharge pipe of the first filter 5-1; the outlet pipe of the sewage pump 4-3 is connected to the inlet of the first water inlet valve 5-4, the second water inlet valve 5-5 and the third water inlet valve 5-6 respectively through a tee, and the outlet pipes of the first automatic drain valve 5-13, the second automatic drain valve 5-14 and the third automatic drain valve 5-15 are connected to the inlet of the electrochemical reactor 6 through a tee; the PLC controller 8 is connected to the motor, water inlet valve, external pressure valve, internal pressure valve, automatic drain valve and automatic mud discharge valve of the first filter component, the second filter component and the third filter component respectively.

[0024] The first filter 5-1 is provided with a first support frame 501 along its length, a filter plate is provided on the outside of the first support frame 501, a filter membrane 503 is provided on the filter plate, a scraper 502 is provided on the outside of the filter membrane 503, the lower end of the scraper 502 is fixedly installed on the bottom surface of the first filter 5-1, the central axis hole of the filter plate is connected to the motor shaft of the motor 5-22, the control end of the motor 5-22 is connected to the PLC controller 8, the second filter 5-2 and the third filter 5-3 have the same structure as the first filter 5-1; the swimming pool water enters the first filter 5-1, and after being filtered by the filter membrane 503, the effluent is discharged through the first automatic drain valve 5-13, and the melamine cyanurate on the surface of the filter membrane 503 is driven by the motor 5-22 to drive the filter plate, thereby driving the filter membrane 503 to rotate and be scraped off by the scraper 503 and enter the recovery bag through the first automatic mud discharge valve 5-16.

[0025] It should be noted that the control end of the motor 5-22 is connected to the PLC controller 8, and the scraper 502 is fixed. When the first water inlet valve 5-4 is closed, the motor 5-22 of the PLC controller 8 works, thereby driving the filter membrane 503 on the filter plate to rotate, and the melamine cyanurate on the surface of the filter membrane 503 is scraped off by the scraper 502.

[0026] The pore size of the filter membrane 503 is 30-50 μm.

[0027] When the present invention is in specific operation,

[0028] S1. Pool water enters the first reaction tank 1. The urease solution in the first reagent tank 1-1 enters the first reaction tank 1 through the reagent pump. The urea probe 1-3 monitors the urea concentration in the first reaction tank 1 in real time and feeds it back to the PLC controller 8. When the monitored urea concentration is greater than 0.5 mg / L, the PLC controller 8 controls the first reagent pump 1-4 to pump the urease in the first reagent tank 1-1 into the first reaction tank 1. The first agitator 1-2 is turned on and the reaction is carried out for 15-20 minutes. The urease reacts with urea to produce NH4 + -N and carbon dioxide, the effluent enters the second reaction tank 2;

[0029] S2, NH4 in the second reaction tank 2 + -N and PO4 3- -P probe 2-3 real-time monitoring of NH4 in reaction pool 2 + -N、PO4 3- -P concentration and feed it back to the PLC controller 8, which controls the second reagent pump 2-4 to pump the MgCl2 solution in the second reagent tank 2-1 into the reaction tank 2 to react with the urea decomposition product NH4 + -N and NH4 in swimming pool water + -N and PO4 3--P generates struvite MgNH4PO4·6H2O, controlling Mg:NH4 + :PO4 3- =1:1:1, turn on the second agitator 2-2, react for 15-20 minutes, recover the struvite by gravity precipitation, and the mixed solution enters the sedimentation tank 3, where it settles for 15-20 minutes, and the supernatant enters the third reaction tank 4;

[0030] S3, the melamine solution in the third reagent tank 4-1 enters the third reaction tank 4 through the third reagent pump 4-6, so that the ratio of cyanuric acid ion in the water to melamine is 1:0.5-0.7, the agitator 4-2 is turned on, the melamine solution reacts with the cyanuric acid ion in the water to form melamine cyanurate (C5H3Cl3O3) precipitate, the pH-cyanuric acid probe 4-5 in the third reaction tank 4 monitors the pH and cyanuric acid concentration in the third reaction tank 4 in real time and feeds back to the PLC controller 8, when the monitored pH is less than 6.0, the PLC controller 8 controls the fourth reagent pump 4-7 to pump the 2 mol / L NaOH solution in the fourth reagent tank 4-4 into the third reaction tank 4, controls the pH in the third reaction tank 4 to be 7.0-7.5, reacts for 15-20 minutes, and the mixed solution is pumped into the cyanuric acid recovery tank 5 through the sewage pump 4-3;

[0031] S4, after the supernatant enters the cyanuric acid recovery tank 5, it enters the first filter 5-1 through the first water inlet valve 5-4 for filtration to remove cyanurate in the water. The filtered swimming pool water is discharged through the first automatic drain valve 5-13. Melamine cyanurate is intercepted on the surface of the filter membrane and gradually forms a filter cake. The gradual thickening of the filter cake will increase the internal and external pressure difference. The first external pressure valve 5-7 and the second internal pressure valve 5-8 monitor the pressure outside and inside the first filter 5-1 in real time and feed it back to the PLC controller 8. The melamine cyanurate accumulated on the surface of the filter membrane 503 will increase, and then form a filter cake, which gradually increases the filtration pressure, resulting in an increasing pressure difference between the internal and external cavities. When the pressure difference between the first external pressure valve 5-7 and the second internal pressure valve 5-8 is greater than 100kPa, the PLC controller 8 controls the first water inlet valve 5-4 to close and the second water inlet valve 5-5 to open. At this time, the swimming pool water can only enter the second filter 5-2 from the second water inlet valve 5-5. The swimming pool water entering the cyanuric acid recovery tank 5 passes through the second water inlet valve 5 -5 enters the second filter 5-2 for processing, and the processing steps are the same as those in the first filter 5-1. When the pressure difference between the second external pressure sensor 5-9 and the second internal sensor 5-10 is greater than 100kPa, the PLC controller 8 controls the second water inlet valve 5-5 to close and opens the third water inlet valve 5-6 at the same time. When the pressure difference between the third external pressure sensor 5-11 and the third internal sensor 5-12 is greater than 100kPa, the PLC controller 8 controls the third water inlet valve 5-6 to close and opens the first water inlet valve 5-4 at the same time. The three filters in the cyanuric acid recovery tank 5 work in sequence. After each filter finishes filtering, it will automatically drain the water and start the motor 5-22 to drive the filter plate to rotate. The filter cake on the filter membrane 503 is scraped off by the scraper 502 and discharged into the recovery bag at the bottom of the cyanuric acid recovery tank 5 through the first automatic mud discharge valve 5-16. The melamine cyanurate in the recovery bag of the cyanuric acid recovery tank 5 is recovered and dehumidified and dried for the production of halogen-free flame retardant. The filtered swimming pool water enters the electrochemical reactor 6;

[0032] S5. The swimming pool water is treated in an electrochemical reactor 6 to remove disinfection byproducts such as chloroform, dichloromonobromomethane, and bromoform, and further removes substances such as urea from the water. The electrochemical reactor is provided with a stainless steel and titanium ruthenium coated graphene electrode device 6-1 and a DC power supply 6-2. The titanium ruthenium coated graphene electrode serves as an anode. The titanium ruthenium coating can protect the graphene electrode and prevent excessive corrosion. Since the content of cyanuric acid in the swimming pool water must be guaranteed, a shorter electrolysis time is set to achieve the treatment of only organic matter such as urea, humus, and protein in the swimming pool water, and cyanuric acid is not degraded. Therefore, the electrolysis time is set to 15-20 minutes. The working efficiency of the electrochemical system 6 can be controlled by adjusting the voltage. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the water of the third reaction tank 4 is greater than 100ug / L, the PLC controller starts the DC power supply 6-2 with a power of 2-3mA / cm2 For every 10ug / L increase in the total concentration of chloroform, dichloromonobromoform and bromoform in the swimming pool water entering the electrochemical reactor 6 (compared to 100ug / L), the power of the DC power supply 6-2 increases by 0.5mA / cm 2 For every 10ug / L reduction, the power of DC power supply 6-2 is reduced by 0.5mA / cm 2 , hydraulic retention 15-20min, the treated swimming pool water is pumped into the security filter 7 through the clean water pump 6-3;

[0033] S6. Fine particles are removed from the swimming pool water in the security filter 7, and the effluent enters the clean water tank 9. The urea-cyanuric acid probe 8-1 monitors the cyanuric acid concentration in the water in the clean water tank 9 in real time and feeds back to the PLC controller 8. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the sampled monitoring water is greater than 100ug / L, the PLC controller 8 controls the start of the first reflux pump 8-3 to return the swimming pool water to the electrochemical reactor 6 for further treatment with chloroform, dichloromonobromomethane and bromoform; when the cyanuric acid concentration in the monitored water is greater than 50mg / L, the PLC controller 8 controls the start of the second reflux pump 8-2 to return the swimming pool water to the third reaction tank 4 for re-treatment. At the same time, the PLC controller 8 controls the third chemical pump 4-6 to increase the dosage of melamine. For every 1mg / L increase in the cyanuric acid concentration, the dosage of melamine increases by 0.7mg / L. When the monitored urea concentration in the water is no more than 0.5 mg / L, the cyanuric acid concentration is no more than 50 mg / L, and the total concentration of chloroform, dichlorobromomethane and bromoform is no more than 100 ug / L, it will be returned to the swimming pool for continued use.

[0034] The present invention has achieved good results after being applied and tested. The water quality of the swimming pool water initially entering the first reaction tank 1 is: pH = 7.5-8, cyanuric acid 100mg / L, PO4 3- -P=8mg / L、NH4 + -N=4mg / L, urea 3.5mg / L, after being treated by the device of the present invention, the effluent water quality is: pH=7.5, cyanuric acid=40mg / L, cyanuric acid: melamine=1:0.5, cyanuric acid recovery rate is 50%, PO4 3- -P=2mg / L、NH4 + -N=1 mg / L, urea 0.5 mg / L, see Table 1 for details.

[0035] Table 1 Treatment effect of a swimming pool water harmless treatment and cyanuric acid recovery system

[0036]

[0037] The invention has a scientific and reasonable design, small project area, small project investment and low cost. The cyanuric acid can be recovered by 50%, the urea removal rate is as high as 85.7%, and PO4 3- -P removal rate up to 75%, NH4 + The N removal rate is 75%, and the removal rate of three byproducts, including chloroform, is 66.7%. Long-term circulation can save 30% of disinfectant dosage. The present invention is easy to operate and manage, resistant to load shock, reduces labor intensity, conserves manpower, and recycles wastewater, saving over 90% of water resources. It eliminates secondary pollution, improves swimming pool water quality, achieves comprehensive harmless treatment, and recovers pollutants. The recovered melamine cyanurate is a halogen-free flame retardant with high purity, representing a major innovation in swimming pool water treatment with significant economic and social benefits.

[0038] It should be pointed out that the above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with this profession can make changes or modify the technical content disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention, and all of them fall within the scope of protection of the present invention.

Claims

1. A method for harmless treatment and resource recovery of swimming pool water, characterized in that: The following steps are involved: S1. The swimming pool water enters the first reaction tank (1). The urease solution in the first reagent tank (1-1) enters the first reaction tank (1) through the reagent pump. The urea probe (1-3) monitors the urea concentration in the first reaction tank (1) in real time and feeds back to the PLC controller (8). When the monitored urea concentration is greater than 0.5 mg / L, the PLC controller (8) controls the first reagent pump (1-4) to pump the urease in the first reagent tank (1-1) into the first reaction tank (1). The reaction lasts for 15-20 minutes. The urease reacts with urea to generate NH4 + -N and carbon dioxide, and the effluent enters the second reaction tank (2); S2, NH4 in the second reaction tank (2) + -N and PO4 3- -P probe (2-3) real-time monitoring of NH4 in the second reaction tank (2) + -N、PO4 3- -P concentration and feed it back to the PLC controller (8), the PLC controller (8) controls the second reagent pump (2-4) to pump the MgCl2 solution in the second reagent tank (2-1) into the second reaction tank (2), and reacts with the urea decomposition product NH4 + -N and NH4 in swimming pool water + -N and PO4 3- -P generates struvite MgNH4PO4·6H2O, reacts for 15-20 minutes, and the struvite is recovered by gravity precipitation. The mixed liquid enters the sedimentation tank (3), settles in the sedimentation tank for 15-20 minutes, and the supernatant enters the third reaction tank (4); S3, the melamine solution in the third reagent tank (4-1) enters the third reaction tank (4) through the third reagent pump (4-6), the melamine solution reacts with cyanurate in the water to form melamine cyanurate precipitate, the pH-cyanuric acid probe (4-5) in the third reaction tank (4) monitors the pH and cyanuric acid concentration in the third reaction tank (4) in real time and feeds back to the PLC controller (8), when the monitored pH is less than 6.0, the PLC controller (8) controls the fourth reagent pump (4-7) to pump the alkaline agent in the fourth reagent tank (4-4) into the third reaction tank (4), controls the pH in the third reaction tank (4) to be 7.0-7.5, reacts for 15-20 minutes, and the mixed solution is pumped into the cyanuric acid recovery tank (5) through the sewage pump (4-3); S4, after the supernatant enters the cyanuric acid recovery tank (5), it enters the first filter (5-1) through the first water inlet valve (5-4) for filtration to remove cyanurate in the water. The filtered swimming pool water is discharged through the first automatic drain valve (5-13). Melamine cyanurate is intercepted on the surface of the filter membrane and gradually forms a filter cake. The gradual thickening of the filter cake will increase the internal and external pressure difference. When the pressure difference between the first external pressure valve (5-7) and the first internal pressure valve (5-8) is greater than 100kpa, the PLC controller (8) controls the first water inlet valve (5-4) to close and opens the second water inlet valve (5-5) at the same time. The swimming pool water entering the cyanuric acid recovery tank (5) enters the second filter (5-2) through the second water inlet valve (5-5) for treatment. When the pressure difference between the second external pressure sensor (5-9) and the second internal sensor (5-10) is greater than 100kpa, the PLC controller ( 8) Control the second water inlet valve (5-5) to close, and simultaneously open the third water inlet valve (5-6); when the pressure difference between the third external pressure sensor (5-11) and the third internal pressure sensor (5-12) is greater than 100 kPa, the PLC controller (8) controls the third water inlet valve (5-6) to close, and simultaneously opens the first water inlet valve (5-4); the three filters in the cyanuric acid recovery tank (5) work in sequence; each filter automatically drains water after finishing filtering and starts the motor (5-22) to drive the filter plate to rotate; the filter cake on the filter membrane (503) is scraped off by the scraper (502) and discharged into the recovery bag at the bottom of the cyanuric acid recovery tank (5) through the first automatic mud discharge valve (5-16); the melamine cyanurate in the recovery bag of the cyanuric acid recovery tank (5) is recovered and then dehumidified and dried for the generation of halogen-free flame retardant; the filtered swimming pool water enters the electrochemical reactor (6); S5. The swimming pool water is removed from the electrochemical reactor (6) to remove chloroform, dichloromonobromomethane, and bromoform disinfection byproducts. At the same time, urea substances in the water are further removed. When the total concentration of chloroform, dichloromonobromomethane and bromoform in the third reaction tank (4) is greater than 100 ug / L, the PLC controller starts the DC power supply (6-2) with a power of 2-3 mA / cm 2 For every 10 ug / L increase in the total concentration of chloroform, dichloromonobromoform and bromoform in the swimming pool water entering the electrochemical reactor (6), the power of the DC power supply (6-2) increases by 0.5 mA / cm 2 For every 10 ug / L decrease, the DC power supply (6-2) power decreases by 0.5 mA / cm 2 , hydraulic retention 15-20min, the treated swimming pool water is pumped into the security filter (7) through the clean water pump (6-3); S6. The swimming pool water is filtered to remove fine particles in the safety filter (7), and the effluent enters the clean water tank (9). The urea-cyanuric acid probe (8-1) monitors the cyanuric acid concentration in the water of the clean water tank (9) in real time and feeds back to the PLC controller (8). When the total concentration of chloroform, dichloromonobromomethane and bromoform in the sampled monitoring water is greater than 100 ug / L, the PLC controller (8) controls the start of the first reflux pump (8-3) to return the swimming pool water to the electrochemical reactor (6) for further treatment with chloroform, dichloromonobromomethane and bromoform. When the cyanuric acid concentration in the monitored water is greater than 50 mg / L, the PLC controller (8) controls the start of the second reflux pump (8-2) to return the swimming pool water to the third reaction tank (4) for re-treatment. At the same time, the PLC controller (8) controls the third chemical pump (4-6) to increase the dosage of melamine. For every 1 mg / L increase in the cyanuric acid concentration, the dosage of melamine increases by 0.

7. mg / L; when the urea concentration in the monitored water is no more than 0.5 mg / L, the cyanuric acid concentration is no more than 50 mg / L, and the total concentration of chloroform, dichlorobromomethane and bromoform is no more than 100ug / L, it will be returned to the swimming pool for continued use.

2. The method for harmless treatment and resource recovery of swimming pool water according to claim 1, characterized in that: The amount of melamine solution added in step S3 is cyanuric acid anion in water: melamine = 1:0.5-0.

7.

3. The method for harmless treatment and resource recovery of swimming pool water according to claim 1, characterized in that: The alkaline agent in the fourth reagent box (4-4) is a 2 mol / L NaOH solution.

4. The method for harmless treatment and resource recovery of swimming pool water according to claim 1, characterized in that: The first reaction tank (1), the second reaction tank (2) and the third reaction tank (4) are respectively equipped with a first stirrer (1-2), a second stirrer (2-2) and a third stirrer (4-2).

5. The method for harmless treatment and resource recovery of swimming pool water according to claim 1, characterized in that: The cyanuric acid recovery tank (5) is sequentially equipped with a first filter assembly, a second filter assembly and a third filter assembly of the same structure. The first filter assembly includes a first filter (5-1), a first water inlet valve (5-4), a first external pressure valve (5-7), a first internal pressure valve (5-8), a first automatic drain valve (5-13) and a first automatic mud discharge valve (5-16). The first water inlet valve (5-4) is installed on the inlet pipe of the first filter (5-1), the first external pressure valve (5-7) and the first internal pressure valve (5-8) connected to the interior are installed on the first filter (5-1), and the first automatic drain valve (5-13) is installed on the outlet pipe of the filter screen in the first filter (5-1). A first automatic mud discharge valve (5-16) is installed on the slag discharge port pipe of the first filter (5-1); the outlet pipe of the sewage pump (4-3) is connected to the inlet of the first water inlet valve (5-4), the second water inlet valve (5-5) and the third water inlet valve (5-6) through a tee, and the outlet pipes of the first automatic drain valve (5-13), the second automatic drain valve (5-14) and the third automatic drain valve (5-15) are connected to the inlet of the electrochemical reactor (6) through a tee; the PLC controller (8) is connected to the motor, the water inlet valve, the external pressure valve, the internal pressure valve, the automatic drain valve and the automatic mud discharge valve of the first filter component, the second filter component and the third filter component respectively.

6. The method for harmless treatment and resource recovery of swimming pool water according to claim 1 or 5, characterized in that: The first filter (5-1) is provided with a first support frame (501) along its longitudinal direction, a filter plate is provided on the outside of the first support frame (501), a filter membrane (503) is provided on the filter plate, a scraper (502) is provided on the outside of the filter membrane (503), the lower end of the scraper (502) is fixedly mounted on the bottom surface of the first filter (5-1), the central axis hole of the filter plate is connected to the motor shaft of the motor (5-22), the control end of the motor (5-22) is connected to the PLC controller (8), and the second filter The structures of (5-2) and the third filter (5-3) are the same as the structure of the first filter (5-1); swimming pool water enters the first filter (5-1), is filtered by the filter membrane (503), and is discharged through the first automatic drain valve (5-13); melamine cyanurate on the surface of the filter membrane (503) is driven by the motor (5-22) to drive the filter plate, thereby driving the filter membrane (503) to rotate, be scraped by the scraper (502), and enter the recovery bag through the first automatic mud discharge valve (5-16).

7. The method for harmless treatment and resource recovery of swimming pool water according to claim 6, characterized in that: The pore size of the filter membrane (503) is 30 to 50 μm.

8. The method for harmless treatment and resource recovery of swimming pool water according to claim 1, characterized in that: The electrochemical reactor (6) is provided with a graphene electrode device (6-1) and a DC power supply (6-2) connected thereto, and the DC power supply (6-2) is connected to a PLC controller (8).

Images