A photovoltaic wastewater treatment process and its high efficiency and low consumption

Abstract

This invention relates to a high NH4 content + ‑N, high NO3 — -N and high F — The high-efficiency, low-consumption treatment process for photovoltaic wastewater involves initially removing fluoride from the wastewater, which then enters a synergistic short-cut denitrification tank. Through the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3... — -N denitrification reaction controlled at NO2 — This step, involving the addition of nitrogen (N), avoids full-scale denitrification by combining the effluent from short-cut denitrification with high NH4 levels. + -N silane wastewater is mixed in an intermediate tank and then undergoes efficient denitrification via an anaerobic ammonia oxidation (AAO) reactor. The effluent from the AAO reactor enters the MABR (Maintenance-Based Bioreactor) tank. The unique layered structure of the MABR biofilm ensures that nitrification / short-cut nitrification, AAO, and denitrification / short-cut denitrification reactions occur in the same reactor, achieving deep denitrification and removal of residual COD. This process achieves acid-base balance during the biochemical reactions, saving 100% of the acid and alkali dosage. Sludge production is only 10% of that of traditional denitrification processes under the same load, significantly reducing operating costs.

Description

Technical Field

[0001] This invention relates to the field of industrial wastewater treatment, specifically to photovoltaic wastewater, and more particularly to a high-efficiency, low-consumption treatment process for photovoltaic wastewater. Background Technology

[0002] In recent years, the energy crisis has become increasingly prominent, and the development and utilization of renewable energy is imminent. Solar energy, as a sustainable renewable energy source, has received extensive research. The rational and full utilization of solar energy has become a research hotspot in the scientific community, leading to the rapid development of the photovoltaic industry. While the rapid development of the photovoltaic industry has brought economic benefits, it has also brought new environmental problems. The production process of photovoltaic cells generally generates silane wastewater, texturing wastewater, and etching wastewater. Among them, the silane process generates a large amount of high-concentration ammonia nitrogen wastewater due to the ammonia spraying process. The texturing and etching processes use a large amount of nitric acid and hydrofluoric acid for treatment, and then use high-purity water to clean the raw materials. In this process, wastewater with high concentrations of fluorine and nitrate nitrogen is generated.

[0003] Traditional processes for treating photovoltaic wastewater generally employ a combination of chemical precipitation to remove fluoride first and then biological denitrification. (1) Chemical fluoride removal: Generally, calcium oxide is added to adjust the pH to 9-10 for initial fluoride removal. Then, calcium chloride is added using the same ion effect and combined with flocculants for secondary fluoride removal, keeping the fluoride ion concentration at a low level. Subsequently, acid is added to adjust the pH to neutral conditions to meet the requirements of biochemical treatment. This technology has the disadvantage of large dosage of reagents.

[0004] (2) Nitrogen removal technology: Currently, physical and chemical nitrogen removal technologies are relatively expensive, such as precipitation and membrane separation. Biological nitrogen removal processes are generally used, and traditional biological nitrogen removal processes generally use a combination of nitrification and denitrification. The nitrification process has the disadvantages of high energy consumption and low utilization rate (high aeration energy consumption and low oxygen utilization rate). The denitrification process generally uses heterotrophic denitrification, but heterotrophic denitrification requires a large amount of external organic carbon source. At the same time, the sludge production is large, which leads to an increase in the amount of hazardous waste disposal. In addition, in order to maintain a good denitrification effect, a large amount of acid solution needs to be added to maintain pH stability during the reaction process. This combination process also has the disadvantages of large footprint and low removal rate.

[0005] In summary, traditional photovoltaic wastewater treatment processes have inherent drawbacks such as high energy consumption, large amounts of hazardous waste generated, high operating costs, and low removal rates. With the rapid development of the photovoltaic industry, developing a new, highly efficient, and low-consumption photovoltaic wastewater treatment process will undoubtedly generate significant economic and environmental benefits. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a highly efficient and low-consumption treatment process for photovoltaic wastewater containing high levels of ammonia nitrogen, nitrate nitrogen, and fluoride. This process achieves two-step deep fluoride removal from the photovoltaic wastewater and efficient NO3 removal through internal acid-base balance. — -N, go to NH4 + The goal of -N is to achieve energy conservation, reduce processing costs, and improve processing efficiency.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A photovoltaic wastewater, comprising separately collected high concentrations of NO3 — -N, F—Etching and texturing wastewater and high NH4 content + -N silane wastewater.

[0009] A high-efficiency and low-consumption treatment process for photovoltaic wastewater, step one: removing high-concentration NO3... — -N、F — After homogenization and equalization of etching and texturing wastewater, it is pumped into a defluorination tank. Calcium oxide and flocculant are added to adjust the pH of the wastewater to between 7.8 and 8 for preliminary defluorination, controlling the concentration of fluoride ions to within 500 mg / L.

[0010] Step Two: The wastewater from Step One is connected to a synergistic short-cut denitrification tank. Through the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 — The conversion rate of -N is 80-85%, and the total nitrogen removal rate is over 10-15%;

[0011] Step 3: After the reaction in the synergistic short-cut denitrification tank is completed, allow it to settle for 0-2 hours, then allow it to flow by gravity into the intermediate water tank, while simultaneously increasing the NH4 content. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The mixing ratio of -N is 1-1.5;

[0012] Step 4: The prepared wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to remove NH4+. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 90-95%, NH4 + -N removal rate is 95-98%;

[0013] Step 5: The water from Step 4 enters the MABR reactor. Utilizing the layered structure of the MABR biofilm, nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions are carried out in the same reactor for deep denitrification and removal of residual COD. After completion, the COD removal rate is 84-86%, the ammonia nitrogen removal rate is 83-85%, and the total nitrogen removal rate is 86-89%.

[0014] Step 6: The effluent from the MABR reactor is transferred to the deep defluoridation tank. The deep defluoridation tank adopts a two-stage defluoridation process. The first stage involves adding calcium oxide and calcium chloride, and the second stage involves adding polymeric flocculants and defluorinating agents. Deep defluoridation is completed under the condition that the pH value is 8.8-9.2.

[0015] Furthermore, the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification was completed in a sequencing batch reactor. The inoculated sludge was anaerobic granular sludge with a particle size of 1-5 mm, and the electron donors were Na2S2O3 and CH3COONa. The process conditions for acclimation were: MLVSS / MLSS: 0.72, C / N ratio: 2-2.5, S / N ratio: 1.5-2, temperature: 25±2℃, pH: 8.2-8.6, dissolved oxygen: 0-0.4 mg / L, and hydraulic retention time: 3.2-3.8 h.

[0016] Furthermore, the anaerobic ammonia oxidation reactor has a UASB configuration, and the process conditions for the acclimation process inside the reactor are: temperature 35±1℃, pH 7.5-8.2, external circulation ratio of anaerobic reactor 200%, oxidation-reduction potential -350mv~-100mv, and hydraulic retention time 6-7h.

[0017] Furthermore, the MABR reactor adopts a sequencing batch reactor, the core of which is the membrane module and the biomembrane. The membrane module is a hollow fiber membrane with a filament diameter of 1.8 mm and a pore size of 0.1-1 µm.

[0018] Preferably, the hollow fiber membrane is a polytetrafluoroethylene hollow fiber membrane.

[0019] Furthermore, anaerobic ammonia-oxidizing bacteria and anoxic flocculent sludge were inoculated into the MABR reactor at a ratio of 1:1. The acclimation conditions in the reactor were as follows: temperature 30±1℃, pH 7.4-8.4, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14mg / L, hydraulic retention time 6h, and aeration pressure 0.022Mpa.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. For high concentrations of NO3 after preliminary defluorination — -N、F— The etching and texturing wastewater is treated using an "autotrophic / heterotrophic synergistic short-cut denitrification" process. This process synergistically combines heterotrophic short-cut denitrification with sulfur autotrophic short-cut denitrification, achieving acid-base equilibrium during the biochemical reaction. This saves 100% of the acid and alkali dosage and 64% of the external carbon source, while also reducing NO3. — -N to NO2 — The conversion rate of -N is 80-85%, which is significantly lower than the 27% conversion rate of traditional denitrification, greatly reducing the cost of reagent addition and sludge treatment.

[0022] 2. The water treated by "autotrophic / heterotrophic synergistic short-cut denitrification" is mixed with high NH4 content. + -N silane wastewater is prepared and then fed into an anaerobic ammonia oxidation reactor. Anaerobic ammonia oxidizing bacteria are used to carry out the "anaerobic ammonia oxidation" reaction, simultaneously removing NH4. + -N and NO2 — -N, resulting in a denitrification rate of 4.6 kg / m³. 3 .d, total nitrogen removal rate is 90-95%, NH4 + -N removal rate is 95-98%, saving 100% of aeration volume and carbon source, sludge production is only 10% of that of traditional denitrification process under the same load, and operating costs are greatly reduced.

[0023] 3. The effluent from the anaerobic ammonia oxidation reactor is connected to the MABR reactor for advanced wastewater treatment. Utilizing the layered structure of the MABR biofilm, nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions are carried out in the same reactor, achieving simultaneous removal of COD, ammonia nitrogen, and total nitrogen. Furthermore, the MABR reactor achieves an oxygen utilization rate of over 42% through precise aeration, reducing energy consumption by half compared to traditional processes.

[0024] 4. By adopting a combined process of preliminary defluorination and terminal deep defluorination, the amount of alkali added can be reduced by 45% and the amount of acid added by 100%, which greatly reduces operating costs. Attached Figure Description

[0025] Figure 1 This is a flowchart of a photovoltaic wastewater treatment process and a high-efficiency, low-consumption treatment technology for photovoltaic wastewater according to the present invention. Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] One embodiment provided by the present invention:

[0028] Example 1:

[0029] like Figure 1 As shown:

[0030] A photovoltaic wastewater, comprising separately collected high concentrations of NO3 — -N, F—Etching and texturing wastewater and high NH4 content + -N silane wastewater.

[0031] A high-efficiency and low-consumption treatment process for photovoltaic wastewater, step one: removing high-concentration NO3... — -N、F — After homogenization and equalization of etching and texturing wastewater, it is pumped into a defluorination tank. Calcium oxide and flocculant are added to adjust the pH of the wastewater to between 7.8 and 8 for preliminary defluorination, controlling the concentration of fluoride ions to within 500 mg / L.

[0032] Step Two: The wastewater from Step One is connected to a synergistic short-cut denitrification tank. Through the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 — The conversion rate of -N is 80-85%, and the total nitrogen removal rate is 10-15%;

[0033] Step 3: After the reaction in the synergistic short-cut denitrification tank is completed, allow it to settle for 0-2 hours, then allow it to flow by gravity into the intermediate water tank, while simultaneously increasing the NH4 content. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The mixing ratio of -N is 1-1.5;

[0034] Step 4: The prepared wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to remove NH4+. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 90-95%, NH4 + -N removal rate is 95-98%;

[0035] Step 5: The water from Step 4 enters the MABR reactor. Utilizing the layered structure of the MABR biofilm, nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions are carried out in the same reactor for deep denitrification and removal of residual COD. After completion, the COD removal rate is 84-86%, the ammonia nitrogen removal rate is 83-85%, and the total nitrogen removal rate is 86-89%.

[0036] Step 6: The effluent from the MABR reactor is transferred to the deep defluoridation tank. The deep defluoridation tank adopts a two-stage defluoridation process. The first stage involves adding calcium oxide and calcium chloride, and the second stage involves adding polymeric flocculants and defluorinating agents. Deep defluoridation is completed under the condition that the pH value is 8.8-9.2.

[0037] In step two, the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification is completed in a sequencing batch reactor. The inoculated sludge is anaerobic granular sludge with a particle size of 1-5 mm, and the electron donors are Na2S2O3 and CH3COONa. The process conditions for acclimation are: MLVSS / MLSS: 0.72, C / N ratio: 2-2.5, S / N ratio: 1.5-2, temperature: 25±2℃, pH: 8.2-8.6, dissolved oxygen: 0-0.4 mg / L, and hydraulic retention time: 3.2-3.8 h.

[0038] Under the aforementioned process conditions, the acclimatization of sulfur autotrophic short-cut denitrification microorganisms and heterotrophic short-cut denitrification microorganisms was completed. Alkali production occurred during the heterotrophic short-cut denitrification reaction, while acid production occurred during the sulfur autotrophic short-cut denitrification reaction. The combined heterotrophic and sulfur autotrophic short-cut denitrification achieved acid-base self-balance in the denitrification system, saving 100% of the acid and alkali dosage and 64% of the external carbon source. This significantly reduced reagent dosage and sludge disposal costs. Simultaneously, the synergistic effect of heterotrophic and sulfur autotrophic short-cut denitrification was controlled, effectively reducing NO3 in the wastewater. — -N denitrification is controlled at NO2 — -N step, and suppress NO2 — -N continues to be restored to N2.

[0039] In step four, the anaerobic ammonia oxidation reaction tower is configured as UASB, and the process conditions for the acclimation process inside the tower are: temperature 35±1℃, pH 7.5-8.2, external circulation ratio of anaerobic tower 200%, oxidation-reduction potential -350mv--100mv, and hydraulic retention time 6-7h.

[0040] Under the combined action of steps three and four, the water treated by "autotrophic / heterotrophic synergistic short-cut denitrification" is mixed with high NH4 content. + -N silane wastewater is prepared and then fed into an anaerobic ammonia oxidation reactor. Anaerobic ammonia oxidizing bacteria are used to carry out the "anaerobic ammonia oxidation" reaction, simultaneously removing NH4.+ -N and NO2 — -N, resulting in a denitrification rate of 4.6 kg / m³. 3 .d, total nitrogen removal rate is 90-95%, NH4 + The nitrogen removal rate is 95-98%, saving 100% of the aeration volume and carbon source. The sludge production is only 10% of that of traditional denitrification processes under the same load, greatly reducing operating costs.

[0041] In step five, the MABR reactor adopts a sequencing batch reactor configuration, the core of which is the membrane module and the biomembrane. The membrane module is a hollow fiber membrane made of polytetrafluoroethylene with a filament diameter of 1.8 mm and a pore size of 0.1-1 µm.

[0042] MABR is a wastewater treatment technology that combines biofilm with aeration membrane material. The biofilm is attached and grows on the outside of the membrane material, and oxygen is transferred from the inside of the membrane to the outside to supply oxygen to the biofilm. The oxygen pressure is kept below the bubble point pressure of the membrane module, so this oxygen supply method is also known as bubble-free aeration.

[0043] Oxygen continuously enters the biofilm under the drive of pressure difference, while the biofilm comes into full contact with pollutants in the water. The pollutants enter the biofilm under the influence of concentration difference and biofilm absorption, forming a heterogeneous mass transfer configuration.

[0044] In the aerobic zone inside the biofilm, the oxygen concentration is the highest and the substrate concentration is relatively low, with short-range nitrifying bacteria and heterotrophic bacteria dominating. On the outer side of the biofilm, the anaerobic environment is controlled to ensure that anaerobic ammonia oxidizing bacteria have good activity. In the middle layer of the biofilm, the dissolved oxygen and substrate concentrations are relatively moderate, which is suitable for the growth of facultative short-range denitrifying bacteria and full-range denitrifying bacteria.

[0045] Therefore, utilizing the unique layered structure of the MABR biofilm, anaerobic ammonia oxidizing bacteria and anoxic flocculent sludge are added to the MABR reactor at a ratio of 1:1. The acclimation process conditions in the reactor are: temperature 30±1℃, pH 7.4-8.4, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14mg / L, hydraulic retention time 6h, and aeration pressure 0.022Mpa. This allows nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions to occur in the same reactor, achieving deep denitrification and removal of residual COD. After acclimation, the COD removal rate is 84-86%, the ammonia nitrogen removal rate is 83-85%, and the total nitrogen removal rate is 86-89%.

[0046] In steps one and six, a combined process of preliminary defluorination and terminal deep defluorination is used, which can reduce the amount of alkali added by 45% and the amount of acid added by 100%, thus greatly reducing operating costs.

[0047] Example 2

[0048] In step two, the wastewater from step one is fed into the synergistic short-cut denitrification tank of the sequencing batch reactor. Through the synergistic effect of short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, the NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 — The conversion rate of -N was 80%, and the total nitrogen removal rate was over 10%. The conditions for completion were: the inoculated sludge was anaerobic granular sludge with a particle size of 3 mm, the electron donors were Na2S2O3 and CH3COONa, and the process conditions for acclimatization were: MLVSS / MLSS: 0.72, carbon-nitrogen ratio of 2, sulfur-nitrogen ratio of 1.5, temperature of 25±2℃, pH of 8.2-8.4, dissolved oxygen of 0-0.1 mg / L, and hydraulic retention time of 3.2 h.

[0049] Example 3

[0050] In step two, the wastewater from step one is fed into the synergistic short-cut denitrification tank of the sequencing batch reactor. Through the synergistic effect of short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 — The conversion rate of -N was 82%, and the total nitrogen removal rate was over 12%. The conditions for completion were: the inoculated sludge was anaerobic granular sludge with a particle size of 2 mm, the electron donors were Na2S2O3 and CH3COONa, and the process conditions for acclimation were: MLVSS / MLSS: 0.72, carbon-nitrogen ratio of 2.2, sulfur-nitrogen ratio of 1.8, temperature of 25±2℃, pH of 8.3-8.5, dissolved oxygen of 0.2-0.3 mg / L, and hydraulic retention time of 3.4 h.

[0051] Example 4

[0052] In step two, the wastewater from step one is fed into the synergistic short-cut denitrification tank of the sequencing batch reactor. Through the synergistic effect of short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 —The conversion rate of -N was 85%, and the total nitrogen removal rate was 15%. The conditions for completion were: the inoculated sludge was anaerobic granular sludge with a particle size of 4 mm, the electron donors were Na2S2O3 and CH3COONa, and the process conditions for acclimation were: MLVSS / MLSS: 0.72, carbon-nitrogen ratio of 2.3, sulfur-nitrogen ratio of 1.9, temperature of 25±2℃, pH of 8.4-8.6, dissolved oxygen of 0.3-0.4 mg / L, and hydraulic retention time of 3.6 h.

[0053] Example 5

[0054] In steps three and four, after the reaction in the synergistic short-cut denitrification tank is completed, the mixture is allowed to settle for 1 hour, then flows by gravity into the intermediate water tank, while simultaneously increasing the NH4 content. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The N-N ratio is 1. The adjusted wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to convert NH4+ into nitrogen. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 90%, NH4 + -N removal rate was 96.2%; the configuration of this anaerobic ammonia oxidation reactor was UASB, and the process conditions for the acclimation process in the tower were: temperature 35±1℃, pH 7.5-7.8, external circulation ratio of anaerobic tower 200%, oxidation-reduction potential -350mv~-100mv, and hydraulic retention time 6h.

[0055] Example 6

[0056] In steps three and four, after the reaction in the synergistic short-cut denitrification tank is completed, the mixture is allowed to settle for 0.5 hours before flowing by gravity into the intermediate water tank, where high NH4 levels are simultaneously introduced. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The N-N ratio is 1-1.5. The adjusted wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to convert NH4+ into nitrogen. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 93%, NH4 + -N removal rate was 95.8%; the configuration of this anaerobic ammonia oxidation reactor was UASB, and the process conditions for the acclimation process in the tower were: temperature 35±1℃, pH 7.5-7.7, external circulation ratio of anaerobic tower was 200%, oxidation-reduction potential was -350mv~-100mv, and hydraulic retention time was 6.5h.

[0057] Example 7

[0058] In steps three and four, after the reaction in the synergistic short-cut denitrification tank is completed, the mixture is allowed to settle for 2 hours and then flows by gravity into the intermediate water tank, while simultaneously increasing the NH4 content. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The N-N ratio is 1.5. The adjusted wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to convert NH4+ into nitrogen. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 94%, NH4 + -N removal rate was 97.3%; the configuration of this anaerobic ammonia oxidation reactor was UASB, and the process conditions for the acclimation process in the tower were: temperature 35±1℃, pH 7.8-8.2, external circulation ratio of anaerobic tower 200%, oxidation-reduction potential -350mv~-100mv, and hydraulic retention time 7h.

[0059] Example 8

[0060] In step five, the MABR reactor adopts a sequencing batch reactor configuration, the core of which is the membrane module and biofilm. The membrane module is a hollow fiber membrane made of polytetrafluoroethylene with a filament diameter of 1.8 mm and a pore size of 0.1-0.3 µm. Utilizing the special layered structure of the MABR biofilm, anaerobic ammonia oxidizing bacteria and anoxic flocculent sludge are added to the MABR reactor at a ratio of 1:1. The process conditions for the acclimation process in the reactor are: temperature 30±1℃, pH 7.4-7.7, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14 mg / L, hydraulic retention time 6 h, and aeration pressure 0.022 MPa. This allows nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions to take place in the same reactor, achieving deep denitrification and removal of residual COD. After completion, the COD removal rate is 84.5%, the ammonia nitrogen removal rate is 83.5%, and the total nitrogen removal rate is 86.6%.

[0061] Example 9

[0062] In step five, the MABR reactor adopts a sequencing batch reactor configuration, the core of which is the membrane module and the biofilm. The membrane module is a hollow fiber membrane made of polytetrafluoroethylene with a filament diameter of 1.8 mm and a pore size of 0.3-0.6 µm. Utilizing the special layered structure of the MABR biofilm, anaerobic ammonia oxidizing bacteria and anoxic flocculent sludge are added to the MABR reactor at a ratio of 1:1. The process conditions for the acclimation process in the reactor are: temperature 30±1℃, pH 7.6-8.0, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14 mg / L, hydraulic retention time 6 h, and aeration pressure 0.022 MPa. This allows nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions to take place in the same reactor, achieving deep denitrification and removal of residual COD. After completion, the COD removal rate is 85.2%, the ammonia nitrogen removal rate is 83.8%, and the total nitrogen removal rate is 87.4%.

[0063] Example 10

[0064] In step five, the MABR reactor adopts a sequencing batch reactor configuration, the core of which is the membrane module and biofilm. The membrane module is a hollow fiber membrane made of polytetrafluoroethylene with a filament diameter of 1.8 mm and a pore size of 0.7-1µm. Utilizing the special layered structure of the MABR biofilm, anaerobic ammonia oxidizing bacteria and anoxic flocculent sludge are added to the MABR reactor at a ratio of 1:1. The process conditions for the acclimation process in the reactor are: temperature 30±1℃, pH 8.1-8.4, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14mg / L, hydraulic retention time 6h, and aeration pressure 0.022Mpa. This allows nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions to take place in the same reactor, achieving deep denitrification and removal of residual COD. After completion, the COD removal rate is 85.8%, the ammonia nitrogen removal rate is 84.6%, and the total nitrogen removal rate is 88.2%.

[0065] Example 11

[0066] In the initial defluorination step one, the pH of the wastewater is adjusted to between 7.5 and 8.0 by adding calcium oxide. The flocculant is cationic polyacrylamide, and the dosage is 1.2-2.5 mg / L.

[0067] In step six, deep defluorination, the pH of the wastewater effluent from the MABR reactor is adjusted to between 8.8 and 9.2, preferably 9.0, by adding calcium oxide. The dosage of calcium chloride is 36-82 mg / L, the dosage of cationic polyacrylamide flocculant is 0.8-1.8 mg / L, and the defluorinating agent is a modified aluminum-iron-silicon polymer, with a dosage of 2.4-4.6 mg / L in the wastewater.

[0068] Step 1: Remove high concentrations of NO3 — -N、F — After homogenization and equalization of etching and texturing wastewater, it is pumped into a defluorination tank. Calcium oxide and flocculant are added to adjust the pH of the wastewater to between 7.8 and 8 for preliminary defluorination, controlling the concentration of fluoride ions to within 500 mg / L.

[0069] The effluent from the MABR reactor is fed into a deep defluoridation tank, which employs a two-stage defluoridation process. The first stage involves the addition of calcium oxide and calcium chloride, while the second stage involves the addition of polymeric flocculants and defluorinating agents. Deep defluoridation is completed under conditions where the pH value is 9.

[0070] Therefore, it can be concluded that by utilizing the autotrophic / heterotrophic synergistic short-cut denitrification process, under the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification, acid-base equilibrium is achieved during the biochemical reaction, saving 100% of the acid and alkali dosage, saving external carbon sources, and simultaneously reducing NO3. — -N to NO2 — The conversion rate of -N is 80-85%, which is significantly lower than the 27% conversion rate of traditional denitrification, greatly reducing the cost of reagent addition and sludge treatment.

[0071] The treated water was then mixed with high NH4 content. + -N silane wastewater is prepared and then fed into an anaerobic ammonia oxidation reactor. Anaerobic ammonia oxidizing bacteria are used to carry out the "anaerobic ammonia oxidation" reaction, simultaneously removing NH4. + -N and NO2 — -N, resulting in a denitrification rate of 4.6 kg / m³. 3 .d, total nitrogen removal rate is 90-95%, NH4 + -N removal rate is 95-98%, saving 100% of aeration volume and carbon source, sludge production is only 10% of that of traditional denitrification process under the same load, and operating costs are greatly reduced.

[0072] The effluent from the anaerobic ammonia oxidation reactor is connected to the MABR reactor for advanced wastewater treatment. Utilizing the layered structure of the MABR biofilm, nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions are carried out in the same reactor, achieving simultaneous removal of COD, ammonia nitrogen, and total nitrogen. Furthermore, the MABR reactor achieves an oxygen utilization rate of over 42% through precise aeration, and energy consumption is reduced by half compared to traditional processes.

[0073] By employing a combined process of preliminary defluorination and terminal deep defluorination, the amount of alkali added can be reduced by 45% and the amount of acid added by 100%, which greatly reduces operating costs.

Claims

1. A high-efficiency and low-consumption treatment process for photovoltaic wastewater, characterized in that: High concentration of NO3 — -N, F — Etching, texturing wastewater and high NH4 + -N silane wastewater, step one: high concentration of NO3 — -N, F — After homogenization and equalization of etching, texturing wastewater, pump into fluoride removal tank, add calcium oxide and flocculants, adjust the pH value of wastewater between 7.8-8 for preliminary fluoride removal, control the concentration of fluoride ions within 500 mg / L; Step Two: The wastewater from Step One is connected to a synergistic short-cut denitrification tank. Through the synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification in the tank, NO3 in the wastewater is removed. — -N denitrification is controlled at NO2 — -N, and inhibit NO2 — -N continues to be reduced to NO2, NO3 — -N to NO2 — The conversion rate of -N is 80-85%, and the total nitrogen removal rate is 10-15%; Step 3: After the reaction in the synergistic short-cut denitrification tank is completed, allow it to settle for 0-2 hours, then allow it to flow by gravity into the intermediate water tank, while simultaneously increasing the NH4 content. + -N silane wastewater is connected to an intermediate water tank, and NO2 in the two wastewater streams... — -N / NH4 + The mixing ratio of -N is 1-1.5; Step 4: The prepared wastewater is pumped into the anaerobic ammonia oxidation reactor, and anaerobic ammonia oxidation bacteria are introduced to remove NH4+. + -N and NO2 — The -N reaction produces N2 and a small amount of NO3. — -N, after this reaction, the total nitrogen removal rate is 90-95%, NH4 + -N removal rate is 95-98%; Step 5: The water from Step 4 enters the MABR reactor. Utilizing the layered structure of the MABR biofilm, nitrification / short-cut nitrification, anaerobic ammonia oxidation, and denitrification / short-cut denitrification reactions are carried out in the same reactor for deep denitrification and removal of residual COD. After completion, the COD removal rate is 84-86%, the ammonia nitrogen removal rate is 83-85%, and the total nitrogen removal rate is 86-89%. Step 6: The effluent from the MABR reactor is transferred to the deep defluoridation tank. The deep defluoridation tank adopts a two-stage defluoridation process. The first stage involves adding calcium oxide and calcium chloride, and the second stage involves adding polymeric flocculants and defluorinating agents. Deep defluoridation is completed under the condition that the pH value is 8.8-9.

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2. The high-efficiency and low-consumption treatment process for photovoltaic wastewater according to claim 1, characterized in that: The synergistic effect of heterotrophic short-cut denitrification and sulfur autotrophic short-cut denitrification was completed in a sequencing batch reactor. The inoculated sludge was anaerobic granular sludge with a particle size of 1-5 mm. The electron donors were Na2S2O3 and CH3COONa. The acclimation process conditions were: MLVSS / MLSS: 0.72, C / N ratio: 2-2.5, S / N ratio: 1.5-2, temperature: 25±2℃, pH: 8.2-8.6, dissolved oxygen: 0-0.4 mg / L, and hydraulic retention time: 3.2-3.8 h.

3. The high-efficiency and low-consumption treatment process for photovoltaic wastewater according to claim 1, characterized in that: The anaerobic ammonia oxidation reactor has a UASB configuration. The process conditions for the acclimation process inside the reactor are: temperature 35±1℃, pH 7.5-8.2, external circulation ratio of anaerobic reactor 200%, oxidation-reduction potential -350mv~-100mv, and hydraulic retention time 6-7h.

4. The high-efficiency and low-consumption treatment process for photovoltaic wastewater according to claim 1, characterized in that: The MABR reactor uses a sequencing batch reactor, the core of which is the membrane module and the biomembrane. The membrane module is a hollow fiber membrane with a filament diameter of 1.8 mm and a pore size of 0.1-1 µm.

5. The high-efficiency and low-consumption treatment process for photovoltaic wastewater according to claim 4, characterized in that: The hollow fiber membrane is made of polytetrafluoroethylene.

6. The high-efficiency and low-consumption treatment process for photovoltaic wastewater according to claim 4, characterized in that: Anaerobic ammonia-oxidizing bacteria and anoxic flocculent sludge were inoculated in the MABR reactor at a ratio of 1:

1. The acclimation conditions in the reactor were as follows: temperature 30±1℃, pH 7.4-8.4, reactor circulation ratio 200%, dissolved oxygen 0.02-0.14mg / L, hydraulic retention time 6h, and aeration pressure 0.022Mpa.

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