A photocatalytic treatment device and method for treating yellow water

Abstract

This invention provides a photocatalytic treatment device and method for treating yellow water. The photocatalytic treatment device includes, in sequence, an ammonia stripping and collection chamber, a reaction crystallization chamber, a columnar adsorption chamber, a photocatalytic reaction chamber, an anoxic conversion chamber, and an aerobic separation chamber. The treatment device first adds a denitrification aid during aeration, improving stripping efficiency. The stripped ammonia is recovered and reused, avoiding secondary pollution. Second, a mixed packing material of biochar and magnesium oxide is used to recover nutrients such as nitrogen and phosphorus from urine through physical adsorption and chemical precipitation. Finally, the treatment device provided by this invention has a simple structure, is easy to install and operate, and simultaneously achieves wastewater reuse, reaching the goal of zero wastewater discharge and conserving water resources.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a photocatalytic treatment device and method for treating yellow water. Background Technology

[0002] Yellow water refers to mixed sewage containing urine and flushing fluid. It is rich in nutrients such as nitrogen, phosphorus, and potassium. Moreover, yellow water accounts for less than 1% of the total volume of urban sewage, making it easy to collect and manage. Therefore, collecting, treating, and recycling its nutrients has become one of the current research hotspots.

[0003] Chinese patent "A Urine and Fecal Waste Resource Treatment Device" (201911058871.8) discloses a urine and fecal waste resource treatment device, including a urine and fecal waste separation toilet, a yellow water and grey water treatment system, and a fermentation and biodegradation fecal waste system. The urine and fecal waste separation toilet separates and recycles urine and feces discharged by humans. The yellow water and grey water treatment system includes an equalization tank, a microalgae cultivation device, and a metal-based electrodynamic membrane. The equalization tank receives urine and domestic sewage from the urine and fecal waste separation toilet and adjusts their ratio. The equalization tank is connected to the microalgae cultivation device via pipes. The microalgae cultivation device regulates the carbon, nitrogen, and phosphorus elements... The microalgae cultivation device's effluent pipe is connected to a metal-based electrodynamic membrane for absorption. This membrane comprises a metal microfiltration membrane, a stainless steel mesh, and a power source. The positive terminal of the power source is connected to the metal microfiltration membrane, and the stainless steel mesh is connected to the negative terminal. The metal microfiltration membrane is used to collect microalgae. The fermentation and biodegradation system includes a collection and conditioning device, a fermentation bed, and a biodegradation chamber. The collection and conditioning device receives and mixes the feces, kitchen waste, and livestock manure separated from the urine-feces separation toilet, adjusting their proportions. The collection and conditioning device is connected to the fermentation bed, which ferments the mixture and introduces the fermented residue into the biodegradation chamber. This invention is less affected by climate conditions and has a wide applicability in my country. However, the aforementioned invention suffers from complex operation and high processing costs. Summary of the Invention

[0004] In order to solve the technical problems of yellow water treatment and overcome the defects of the above-mentioned patents, the present invention aims to provide a yellow water photocatalytic treatment device and treatment method that is simple to operate and requires less investment.

[0005] The technical solution adopted by this invention to solve its technical problem is:

[0006] This invention provides a photocatalytic treatment device for wastewater, comprising, in sequence, an ammonia stripping and collection chamber, a reaction crystallization chamber, a columnar adsorption chamber, a photocatalytic reaction chamber, an anoxic conversion chamber, and an aerobic separation chamber. The ammonia stripping and collection chamber is used to denitrify the wastewater and collect the generated ammonia for reuse, before the wastewater is transported to the reaction crystallization chamber. The reaction crystallization chamber is used to adjust the pH of the wastewater by adding magnesium and phosphorus sources, and to collect the resulting precipitates, before the wastewater is transported to the columnar adsorption chamber. The columnar adsorption chamber is used for filtering and adsorbing the wastewater. The resulting precipitate is collected, and the wastewater is then transported to the photocatalytic reaction chamber. The photocatalytic reaction chamber is used to degrade the organic pollutants in the wastewater, and the wastewater is then transported to the anoxic conversion chamber. The anoxic conversion chamber is used to decompose large-molecule organic matter in the wastewater into small-molecule organic matter and convert insoluble organic matter into soluble organic matter. The wastewater after the reaction is separated into mud, water, and methane gas, and then transported to the aerobic separation chamber. The aerobic separation chamber is used to filter the wastewater again to remove pollutants and to aerate the water to increase its activity.

[0007] Furthermore, the ammonia stripping and collection chamber, reaction crystallization chamber, column adsorption chamber, photocatalytic reaction chamber, anoxic conversion chamber, and aerobic separation chamber are arranged in two parallel rows; wherein the ammonia stripping and collection chamber, reaction crystallization chamber, and column adsorption chamber are located in one row, and the photocatalytic reaction chamber, anoxic conversion chamber, and aerobic separation chamber are located in the other row.

[0008] Furthermore, the ammonia stripping collection chamber includes an inlet at the bottom and an outlet in the middle; an ammonia stripping collection chamber inlet pipe is installed at the inlet, and an ammonia stripping collection chamber water distributor is installed at the outlet of the inlet pipe, while a stripping agent addition metering system is installed at the inlet; above the ammonia stripping collection chamber inlet pipe, from bottom to top, are an aeration system, an ammonia stripping collection chamber alkali addition inlet, and an ammonia stripping collection chamber pH measuring device; a gas-liquid separator is installed at the outlet; and the top of the ammonia stripping collection chamber also includes... An ammonia collection pipe is provided, and a fan for discharging ammonia is installed in the ammonia collection pipe; the top of the ammonia stripping and collection chamber also contains a sulfuric acid solution with a mass concentration of 2% to 5%, which is used to absorb ammonia and generate ammonium sulfate for reuse; wherein, the stripping agent used in the stripping agent addition metering system is a mixture of 20% to 60% methyl ethyl ketone, 20% to 60% polyvinyl polyamine salt, 20% to 60% hydroxyethyl cellulose ether and 20% to 65% sodium hypochlorite by mass ratio, and the amount of stripping agent added is 20 ppm to 50 ppm.

[0009] Furthermore, the reaction crystallization chamber includes a stirring zone and a precipitation zone located below the stirring zone; the upper part of the stirring zone is provided with a reagent addition device for adding magnesium and phosphorus sources and a pH measuring device for the reaction crystallization chamber, and the middle part is provided with an alkali addition inlet for the reaction crystallization chamber; a stirring device is also provided in the stirring zone; the precipitation zone has a conical structure, and a precipitate discharge valve is provided at the bottom of the conical structure.

[0010] Furthermore, the columnar adsorption chamber is provided with adsorption packing material in the middle, and the upper and lower ends of the adsorption packing material are respectively filled with upper and lower pebble pads, and filter screens are provided on the side of the adsorption packing material adjacent to the upper and lower pebble pads; columnar adsorption chamber water distributors are also provided at the bottom and top of the columnar adsorption chamber; wherein, the adsorption packing material is a mixture of biochar and magnesium oxide, and the mass ratio of biochar to magnesium oxide is 10:1; the raw materials of biochar include waste materials of corn stalks and wheat stalks.

[0011] Furthermore, the photocatalytic reaction chamber is provided with several photocatalytic baffles, and two adjacent photocatalytic baffles are staggered in a parallel manner on the top and bottom of the photocatalytic reaction chamber; the surface of the photocatalytic baffle is provided with several small grooves, and the grooves contain photocatalysts.

[0012] Furthermore, the photocatalyst is specifically a bismuth oxide / bismuth molybdate composite photocatalyst, and the preparation method of the photocatalyst includes:

[0013] S1. Preparation of bismuth molybdate: 1.3 mmol of bismuth nitrate pentahydrate and 0.65 mmol of sodium molybdate crystals were vortexed in 13 ml of ethylene glycol until completely homogenized. Then, 32.5 ml of ethanol was added and stirred for 30 min to 120 min. The mixture was then transferred to a polytetrafluoroethylene stainless steel autoclave and subjected to solvothermal treatment at 120 °C to 190 °C for 10 h to 24 h. After the reaction was completed, the precipitate was collected by filtration and then washed with ethanol and deionized water, respectively, and dried at 60 °C to 90 °C for 10 h to 24 h.

[0014] S2. Preparation of bismuth oxide: Dissolve 1.6866g of bismuth nitrate pentahydrate in 40ml of ethylene glycol solution, stir at 15℃~20℃ until a homogeneous solution is formed, and adjust the pH value to 8.0~9.0. Pour the solution into a stainless steel autoclave lined with tetrafluoroethylene and heat at 160℃~190℃ for 3h~10h. When the autoclave cools naturally to room temperature, centrifuge the obtained sample, wash it 3~5 times with distilled water and anhydrous ethanol, and then dry it at 70℃~90℃ for 12h~36h; wherein, the ethylene glycol solution is prepared by mixing ethylene glycol and water in a mass ratio of 5:3.

[0015] Preparation of S3, Bismuth Oxide / Bismuth Molybdate Composite Photocatalyst: Bismuth oxide obtained in step S2 was added to ethanol to obtain a bismuth oxide solution. Bismuth molybdate obtained in step S1 was added to ethanol to obtain a bismuth molybdate solution. The bismuth oxide solution and the bismuth molybdate solution were ultrasonicated for 1-3 hours respectively. The bismuth oxide solution was then added to the bismuth molybdate solution, and the mixture was ultrasonicated for 2-4 hours to obtain a mixed solution. Then, 10-20 ml of acetone was added to the mixed solution, and the mixture was stirred for 12-36 hours. After precipitation, the mixture was dried to obtain the bismuth oxide / bismuth molybdate composite photocatalyst. The concentration of bismuth oxide in the mixed solution was 6.67 × 10⁻⁶. -6 The concentration of bismuth molybdate is 1.2 × 10 mol / L. -5 mol / L; the volume ratio of the mixed solution to acetone added is 2:1.

[0016] Furthermore, the top plate of the anoxic conversion chamber is inclined, with its highest point connected to the photocatalytic reaction chamber 4 and its lowest point connected to the aerobic separation chamber 6; a gas collecting pipe is installed at the highest point of the top plate, which is connected to an exhaust pipe for discharging methane gas; a packing hook is installed on the top plate of the anoxic conversion chamber, on which anoxic packing is suspended; a three-phase separator is installed at the outlet of the anoxic conversion chamber; the bottom of the anoxic conversion chamber has a conical structure, and an anoxic conversion chamber discharge valve is installed at the bottom of the conical structure.

[0017] Furthermore, the top of the aerobic separation chamber is provided with an aerobic separation chamber inlet pipe, and the outlet of the aerobic separation chamber inlet pipe is provided with an aerobic separation chamber water distributor. The lower part of the aerobic separation chamber water distributor is provided with aerobic packing material, and the lower part of the aerobic packing material is provided with an aeration pipe to increase the activity of the water. The aerobic packing material is made of aldehyde fiber or polyester filament.

[0018] The present invention also provides a photocatalytic treatment method for yellow water, applied to the yellow water photocatalytic treatment device described above, comprising the following steps:

[0019] ① The wastewater enters the ammonia stripping and collection chamber, a denitrification aid is added, and the pH of the wastewater is adjusted to 8-12; then, the wastewater is kept at 25℃-55℃ for 60-150 minutes for aeration and gas-liquid separation. The free ammonia in the wastewater is then collected and mixed with sulfuric acid solution to generate ammonium sulfate for reuse.

[0020] ② Wastewater enters the reaction crystallization chamber, and magnesium, phosphorus, and alkali sources are added to achieve a Mg:K:P molar ratio of 3.3:1:3.3. Simultaneously, the pH of the wastewater is adjusted to 8–11. The mixture is then stirred to generate magnesium ammonium phosphate, magnesium potassium phosphate, and magnesium sodium sulfate. These substances settle to the sedimentation zone at the bottom of the reaction crystallization chamber under gravity, where they are discharged, dehydrated, dried, and recycled. The magnesium source is MgCl2·H2O, the phosphorus source is Na2HPO4·12H2O, and the alkali source is NaOH.

[0021] ③ The wastewater enters the columnar adsorption chamber and is filtered and adsorbed sequentially through the lower pebble pad, adsorption packing, and top pebble pad to generate magnesium phosphate and magnesium ammonium phosphate for recycling.

[0022] ④ The wastewater enters the photocatalytic reaction chamber and circulates alternately through each photocatalytic baffle to degrade the organic pollutants in the wastewater;

[0023] ⑤ The wastewater enters the anoxic conversion chamber. Under the action of the anoxic packing, the large molecular organic matter in the wastewater is decomposed into small molecular organic matter, and the insoluble organic matter is converted into soluble organic matter. Then, under the action of the three-phase separator, the mud, water and methane gas are separated, and the methane gas is then recovered and reused, while the sludge is discharged.

[0024] ⑥ The wastewater enters the aerobic separation chamber, where it is filtered and pollutants are removed by aerobic packing material. At the same time, the wastewater is aerated to increase the activity of the water. The treated wastewater is then discharged.

[0025] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0026] 1. This invention adds a denitrification aid during the aeration process, improving the stripping efficiency. The stripped ammonia gas is recovered and reused, avoiding secondary pollution;

[0027] 2. By using a mixture of biochar and magnesium oxide as filler, nutrients such as nitrogen and phosphorus in urine can be recovered through physical adsorption and chemical precipitation.

[0028] 3. The system has a simple structure and is easy to install and operate. It also realizes wastewater reuse, achieves the goal of zero wastewater discharge, and saves water resources. Attached Figure Description

[0029] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0030] Figure 1 This is a top view of the photocatalytic treatment device for yellow water provided by the present invention;

[0031] Figure 2 This is a schematic diagram of the ammonia stripping and collection chamber, reaction crystallization chamber, and columnar adsorption chamber in this invention;

[0032] Figure 3 This is a schematic diagram of the photocatalytic reaction chamber, the anoxic conversion chamber, and the aerobic separation chamber in this invention;

[0033] In the diagram: 1 Ammonia stripping and collection chamber, 1-1 Ammonia stripping and collection chamber inlet pipe, 1-2 Ammonia stripping and collection chamber water distributor, 1-3 Stripping agent addition metering system, 1-4 Ammonia stripping and collection chamber alkali addition inlet, 1-5 Ammonia stripping and collection chamber pH measuring device, 1-6 Aeration system, 1-7 Gas-liquid separator, 1-8 Ammonia collection pipe;

[0034] 2. Reaction crystallization chamber; 2-1. Reagent solution addition device; 2-2. pH value measuring device for reaction crystallization chamber; 2-3. Alkali solution addition inlet for reaction crystallization chamber; 2-4. Stirring device; 2-5. Precipitate discharge valve.

[0035] 3. Columnar adsorption chamber; 3-1. Columnar adsorption chamber water distributor; 3-2. Adsorption packing; 3-3. Lower pebble pad; 3-4. Upper pebble pad; 3-5. Columnar adsorption chamber outlet pipe.

[0036] 4. Photocatalytic reaction chamber; 4-1. Photocatalytic separator;

[0037] 5. Anoxic conversion chamber, 5-1. Gas collection pipe, 5-2. Three-phase separator, 5-3. Anoxic conversion chamber discharge valve, 5-4. Anoxic packing;

[0038] 6. Aerobic separation chamber, 6-1. Aerobic separation chamber inlet pipe, 6-2. Aerobic separation chamber water distributor, 6-3. Aerobic packing material, 6-4. Aeration pipe, 6-5. Aerobic separation chamber outlet. Detailed Implementation

[0039] The present invention will be further described in detail below with reference to the embodiments. It should be noted that: unless otherwise specified, the conditions in the following embodiments are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following embodiments can be obtained from commercially available sources.

[0040] Example

[0041] like Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a photocatalytic treatment device for yellow water, comprising an ammonia stripping and collection chamber 1, a reaction crystallization chamber 2, a columnar adsorption chamber 3, a photocatalytic reaction chamber 4, an anoxic conversion chamber 5, and an aerobic separation chamber 6.

[0042] The ammonia stripping collection chamber 1 is equipped with an ammonia stripping collection chamber inlet pipe 1-1 at the bottom, a water distributor 1-2 at the outlet of the ammonia stripping collection chamber inlet pipe 1-1, a stripping agent addition metering system 1-3 in front of the inlet, an alkali addition inlet 1-4 in the middle of the ammonia stripping collection chamber 1, a pH measuring device 1-5 at the top of the ammonia stripping collection chamber 1, an aeration system 1-6 at the bottom of the ammonia stripping collection chamber 1, a gas-liquid separator 1-7 at the outlet of the ammonia stripping collection chamber 1, and an ammonia collection pipe 1-8 at the top of the ammonia stripping collection chamber 1. A fan for discharging ammonia is installed in the ammonia collection pipe 1-8, and the ammonia is collected at the top of the ammonia stripping collection chamber.

[0043] The reaction crystallization chamber 2 includes a stirring zone and a sedimentation zone. The upper part of the reaction crystallization chamber 2 is equipped with a chemical addition device 2-1 for adding magnesium and phosphorus sources and a pH measuring device 2-2. The middle part of the reaction crystallization chamber is equipped with an alkali addition inlet 2-3 for adjusting the pH value. A stirring device 2-4 is installed in the stirring zone. The sedimentation zone is designed with a conical structure, and a sediment discharge valve 2-5 is installed at the bottom of the sedimentation zone.

[0044] Water distributors 3-1 are installed at both the bottom and top of the columnar adsorption chamber 3 to ensure uniform water intake. Adsorption packing material 3-2 is installed in the middle of the columnar adsorption chamber 3. The lower end of the adsorption packing material 3-2 is filled with a lower pebble pad 3-3 and the upper end with a pebble pad 3-4, respectively. A filter screen is placed between the adsorption packing material 3-2 and the lower and upper pebble pads 3-3 and 3-4, respectively. On the one hand, this is to prevent a large amount of adsorption packing material 3-2 from clogging the water distributor 3-1 as it enters the solution. On the other hand, when water enters from the bottom, the less dense adsorption packing material 3-2 tends to float and exert pressure on the top of the columnar adsorption chamber 3. The denser pebbles in the upper pebble pad 3-4 can press down on the adsorption packing material 3-2 to buffer this pressure. The water after adsorption and filtration enters the inlet of the photocatalytic reaction chamber 4 from the outlet pipe 3-5 of the columnar adsorption chamber.

[0045] The photocatalytic reaction chamber 4 is equipped with several photocatalytic baffles 4-1. Two adjacent photocatalytic baffles 4-1 are respectively set and fixed on the top and bottom walls of the photocatalytic reaction chamber 4. Two adjacent photocatalytic baffles 4-1 are parallel to each other. Water flows in sequentially from the lower end of the photocatalytic baffle 4-1 set at the top of the photocatalytic reaction chamber 4 and flows out sequentially from the upper end of the photocatalytic baffle 4-1 set at the bottom of the photocatalytic reaction chamber 4, and alternately circulates. Several small grooves are provided on the surface of the photocatalytic baffles 4-1, and photocatalysts are placed in the grooves.

[0046] The top plate of the anoxic conversion chamber 5 is inclined to facilitate the accumulation and recovery of methane gas. Specifically, the highest point of the inclined top plate of the anoxic conversion chamber 5 is connected to the photocatalytic reaction chamber 4, and the lowest point is connected to the aerobic separation chamber 6. A gas collecting pipe 5-1 is designed at the highest point of the top plate of the anoxic conversion chamber 5, which connects to an exhaust pipe that discharges methane gas from the yellow water photocatalytic treatment device. A three-phase separator 5-2 is installed at the outlet of the anoxic conversion chamber 5. The bottom of the anoxic conversion chamber 5 is designed with a conical structure, which connects to the anoxic conversion chamber discharge valve 5-3. A packing hook is installed on the top plate of the anoxic conversion chamber 5, and packing material 5-4 is suspended from the packing hook.

[0047] The top of the aerobic separation chamber 6 is equipped with an aerobic separation chamber inlet pipe 6-1, and the outlet of the aerobic separation chamber inlet pipe 6-1 is equipped with an aerobic separation chamber water distributor 6-2. Below the aerobic separation chamber water distributor 6-2, there is an aerobic packing material 6-3, and below the aerobic packing material 6-3, there is an aeration pipe 6-4 to increase the activity of the water.

[0048] In this embodiment, the stripping agent is composed of 20%–60% butanone, 20%–60% polyvinyl polyamine salt, 20%–60% hydroxyethyl cellulose ether and 20%–65% sodium hypochlorite by mass ratio, and the amount of stripping agent added is 20 ppm–50 ppm.

[0049] In this embodiment, the top of the ammonia stripping and collection chamber 1 is equipped with a sulfuric acid solution with a mass concentration of 2%-5%, which absorbs ammonia and generates ammonium sulfate for reuse.

[0050] In this embodiment, the adsorption filler 3-2 is a mixture of biochar and magnesium oxide; the raw material for biochar is waste biomass such as corn stalks and wheat stalks, and the mass ratio of biochar to magnesium oxide is 10:1.

[0051] In this embodiment, the preparation process of the photocatalyst disposed on the photocatalytic separator 4-1 is as follows:

[0052] Step 1, Preparation of bismuth molybdate: 1.3 mmol of bismuth nitrate pentahydrate and 0.65 mmol of sodium molybdate crystals were vortexed in 13 ml of ethylene glycol until completely homogenized. Then, 32.5 ml of ethanol was added and the solution was stirred for 30 min to 120 min. The mixture was then transferred to a polytetrafluoroethylene stainless steel autoclave and subjected to solvothermal treatment at 120 to 190 °C for 10 h to 24 h. After the reaction was completed, the precipitate was collected by filtration and then washed with ethanol and deionized water, respectively, and dried at 60 °C to 90 °C for 10 h to 24 h.

[0053] Step 2, Preparation of bismuth oxide: Dissolve 1.6866g of bismuth nitrate pentahydrate in 40ml of ethylene glycol (EG) solution (EG / H2O = 5 / 3), stir at 15℃~20℃ until a homogeneous solution is formed, and adjust the pH value to 8.0~9.0. Pour the solution into a stainless steel autoclave lined with tetrafluoroethylene and heat at 160℃~190℃ for 3h~10h. When the autoclave cools naturally to room temperature, centrifuge the obtained sample, wash it 3~5 times with distilled water and anhydrous ethanol, and then dry it at 70℃~90℃ for 12h~36h.

[0054] Step 3: Preparation of the bismuth oxide / bismuth molybdate composite photocatalyst: The bismuth oxide from step S2 was added to ethanol to obtain a bismuth oxide solution. The bismuth molybdate from step S1 was added to ethanol to obtain a bismuth molybdate solution. The bismuth oxide and bismuth molybdate solutions were sonicated for 1-3 hours respectively. The bismuth oxide solution was then added to the bismuth molybdate solution, and the mixture was sonicated for 2-4 hours. Then, 10-20 ml of acetone was added to the mixture, and the mixture was stirred for 12-36 hours. After precipitation, the mixture was dried to obtain the bismuth oxide / bismuth molybdate composite photocatalyst. The bismuth oxide concentration in the mixture was 6.67 × 10⁻⁶. -6 The concentration of bismuth molybdate is 1.2 × 10 mol / L. -5 mol / L; the volume ratio of the mixed solution to acetone added is 2:1.

[0055] In this embodiment, the aerobic packing material 6-3 in the aerobic separation chamber 6 is made of aldehyde fiber or polyester filament and needs to meet the following requirements: ① low resistance and good biofilm formation ability; ② good oxygen transfer rate and utilization rate during aeration; ③ good heat dissipation and water distribution performance of the packing material; ④ the aerobic packing material is a suspended structure, composed of multiple combined packing material units connected in series.

[0056] The steps for water treatment using the above-mentioned yellow water photocatalytic treatment device are as follows:

[0057] ① The yellow water (hereinafter referred to as wastewater) after adding denitrification aid through the stripping agent addition metering system 1-3 enters the ammonia stripping collection chamber 1 through the bottom water inlet pipe 1-1. The water is evenly distributed by the water distributor 1-2 in the ammonia stripping collection chamber. Alkali solution is added through the alkaline solution addition inlet 1-4 to adjust its pH value to 8-12 (measured by the pH value measuring device 1-5 in the ammonia stripping collection chamber). Under the conditions of 25℃-55℃, the wastewater stays in the ammonia stripping collection chamber 1 for 60min-150min. It is aerated using the aeration system 1-6. The gas-liquid separator 1-7 separates ammonia and water. The free ammonia in the wastewater is collected at the top of the ammonia stripping collection chamber 1 through the ammonia collection pipe 1-8. The ammonia is mixed with sulfuric acid solution to generate ammonium sulfate for reuse.

[0058] ② The wastewater then enters the reaction crystallization chamber 2. Magnesium source (MgCl2·H2O), phosphorus source (Na2HPO4·12H2O), and alkali source (NaOH) are added through the chemical addition device 2-1 at the top of the reaction crystallization chamber 2 for adding magnesium and phosphorus sources, and the alkali addition inlet 2-3 in the middle of the reaction crystallization chamber 2. This ensures that the Mg:K:P molar ratio of the wastewater entering the reaction crystallization chamber 2 is 3.3:1:3.3. Simultaneously, alkali is added through the alkali addition inlet 1-4 to adjust the pH value to approximately 11 (measured by the pH measuring device 2-2 in the reaction crystallization chamber). Under the action of the stirring device 2-4, magnesium ammonium phosphate (struvite), magnesium potassium phosphate, and magnesium sodium sulfate are finally generated. Magnesium ammonium phosphate, magnesium potassium phosphate, and magnesium sodium sulfate settle to the bottom of the reaction crystallization chamber 2 under gravity and are discharged through the sedimentation zone discharge valve 2-5 at the bottom for dehydration, drying, and recycling.

[0059] ③ The wastewater then enters the columnar adsorption chamber 3 through the inlet at the bottom. Under the action of the columnar adsorption chamber distributor 3-1, it passes sequentially through the lower pebble pad 3-3, the adsorption packing 3-2, and the top pebble pad 3-4. A filter screen separates the packing and the pads: on the one hand, to prevent a large amount of packing from entering the distributor with the solution and causing blockage; on the other hand, when water enters from the bottom, the less dense packing tends to float and exert pressure on the top of the columnar adsorption chamber 3, while the more dense pebbles can press down on the packing to buffer this pressure. Under the mixed action of biochar and magnesium oxide, magnesium phosphate and struvite are generated for recycling. The wastewater enters the photocatalytic reaction chamber 4 through the columnar adsorption chamber outlet pipe 3-5.

[0060] ④ The wastewater then enters the photocatalytic reaction chamber 4, and the wastewater alternately circulates through the photocatalytic partition 4-1, where the organic pollutants in the wastewater are degraded by the photocatalyst.

[0061] ⑤ The wastewater is then introduced into the anoxic conversion chamber 5. Inside the anoxic conversion chamber 5, the microorganisms on the anoxic packing material 5-4 decompose the large organic molecules in the wastewater into small organic molecules, and convert insoluble organic matter into soluble organic matter. The wastewater after the reaction is separated into sludge, water and methane gas by the three-phase separator 5-2. The methane gas generated is collected by the gas collection pipe 5-1 and the exhaust pipe of the anoxic conversion chamber and recycled. The sludge settles to the bottom of the anoxic conversion chamber 5 under the action of gravity, and the excess sludge is discharged through the anoxic conversion chamber discharge valve 5-3.

[0062] ⑥ The wastewater finally enters the aerobic separation chamber 6. Under the action of the aerobic separation chamber water distributor 6-2, the wastewater is evenly filtered through the aerobic packing 6-3 to remove pollutants. At the same time, the aeration pipe 6-4 at the bottom aerates the water to increase the activity of the water. The treated water is then discharged through the aerobic separation chamber outlet 6-5 for reuse or further treatment.

[0063] The above description is merely an exemplary embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A photocatalytic treatment device for yellow water, characterized in that, It includes a sequentially connected ammonia stripping and collection chamber, a reaction crystallization chamber, a column adsorption chamber, a photocatalytic reaction chamber, an anoxic conversion chamber, and an aerobic separation chamber; The ammonia stripping and collection chamber is used to denitrify the wastewater and collect the generated ammonia for reuse, and then the wastewater is transported to the reaction crystallization chamber. The reaction crystallization chamber is used to adjust the pH value of the wastewater by adding magnesium and phosphorus sources, and to collect the precipitates generated before transporting the wastewater to the columnar adsorption chamber. The columnar adsorption chamber is used to filter and adsorb wastewater, collect the resulting precipitates, and then transport the wastewater to the photocatalytic reaction chamber. The photocatalytic reaction chamber is used to degrade organic pollutants in wastewater, and then the wastewater is transported to the anoxic conversion chamber. The anoxic conversion chamber is used to decompose large organic molecules in wastewater into small organic molecules and convert insoluble organic molecules into soluble organic molecules. It also separates mud, water, and methane gas from the wastewater after the reaction and transports the wastewater to the aerobic separation chamber. The aerobic separation chamber is used to further filter wastewater to remove pollutants and to aerate the water to increase its activity. The ammonia stripping and collection chamber, reaction crystallization chamber, column adsorption chamber, photocatalytic reaction chamber, anoxic conversion chamber, and aerobic separation chamber are arranged in two parallel rows. The ammonia stripping and collection chamber, the reaction crystallization chamber, and the columnar adsorption chamber are located in one column, while the photocatalytic reaction chamber, the anoxic conversion chamber, and the aerobic separation chamber are located in another column. The ammonia stripping and collection chamber includes a stripping agent addition and metering system. The stripping agent used in the stripping agent addition and metering system is a mixture of 20%~60% methyl ethyl ketone, 20%~60% polyvinyl polyamine salt, 20%~60% hydroxyethyl cellulose ether and 20%~65% sodium hypochlorite by mass ratio. The amount of stripping agent added is 20ppm~50ppm. The columnar adsorption chamber is provided with an adsorption packing material in the middle, which is a mixture of biochar and magnesium oxide.

2. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The ammonia stripping and collection chamber includes an inlet at the bottom and an outlet in the middle. An ammonia stripping and collection chamber inlet pipe is installed at the inlet. An ammonia stripping and collection chamber water distributor is installed at the outlet of the ammonia stripping and collection chamber inlet pipe, and a stripping agent addition metering system is installed at the inlet. An aeration system, an ammonia stripping and collection chamber alkali addition inlet, and an ammonia stripping and collection chamber pH value measuring device are installed sequentially from bottom to top above the ammonia stripping and collection chamber inlet pipe. A gas-liquid separator is installed at the water outlet; The top of the ammonia stripping and collection chamber is also equipped with an ammonia collection pipe, and a fan for discharging ammonia is installed in the ammonia collection pipe; the top of the ammonia stripping and collection chamber also contains a sulfuric acid solution with a mass concentration of 2% to 5%, which is used to absorb ammonia and generate ammonium sulfate for reuse.

3. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The reaction crystallization chamber includes a stirring zone and a precipitation zone disposed below the stirring zone; The upper part of the stirring zone is equipped with a chemical addition device for adding magnesium and phosphorus sources and a pH measuring device for the reaction crystallization chamber; the middle part is equipped with an alkali addition inlet for the reaction crystallization chamber; and a stirring device is also provided in the stirring zone. The sedimentation zone has a conical structure, and a sediment discharge valve is provided at the bottom of the conical structure.

4. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The upper and lower ends of the adsorption packing are respectively filled with an upper pebble pad and a lower pebble pad, and a filter screen is provided on the side of the adsorption packing adjacent to the upper and lower pebble pads. The bottom and top of the columnar adsorption chamber are respectively provided with columnar adsorption chamber water distributors; The biochar and magnesium oxide are mixed in a mass ratio of 10:1; the raw materials for the biochar include waste materials from corn stalks and wheat stalks.

5. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The photocatalytic reaction chamber is provided with several photocatalytic baffles, and two adjacent photocatalytic baffles are staggered in a parallel manner on the top and bottom of the photocatalytic reaction chamber; the surface of the photocatalytic baffle is provided with several small grooves, and the grooves contain photocatalysts.

6. The photocatalytic treatment device for yellow water according to claim 5, characterized in that, The photocatalyst is specifically a bismuth oxide / bismuth molybdate composite photocatalyst, and the preparation method of the photocatalyst includes: S1. Preparation of bismuth molybdate: 1.3 mmol of bismuth nitrate pentahydrate and 0.65 mmol of sodium molybdate crystals were vortexed in 13 ml of ethylene glycol until completely homogenized. Then, 32.5 ml of ethanol was added and stirred for 30 min to 120 min. The mixture was then transferred to a polytetrafluoroethylene stainless steel autoclave and subjected to solvothermal treatment at 120 °C to 190 °C for 10 h to 24 h. After the reaction was completed, the precipitate was collected by filtration and then washed with ethanol and deionized water, respectively, and dried at 60 °C to 90 °C for 10 h to 24 h. S2. Preparation of bismuth oxide: Dissolve 1.6866g of bismuth nitrate pentahydrate in 40ml of ethylene glycol solution, stir at 15℃~20℃ until a homogeneous solution is formed, and adjust the pH value to 8.0~9.

0. Pour the solution into a stainless steel autoclave lined with tetrafluoroethylene and heat at 160℃~190℃ for 3h~10h. When the autoclave cools naturally to room temperature, centrifuge the obtained sample, wash it 3~5 times with distilled water and anhydrous ethanol, and then dry it at 70℃~90℃ for 12h~36h. The ethylene glycol solution is prepared by mixing ethylene glycol and water in a mass ratio of 5:

3. S3. Preparation of bismuth oxide / bismuth molybdate composite photocatalyst: Bismuth oxide obtained in step S2 is added to ethanol to obtain a bismuth oxide solution. Bismuth molybdate obtained in step S1 is added to ethanol to obtain a bismuth molybdate solution. The bismuth oxide solution and the bismuth molybdate solution are ultrasonicated for 1-3 hours respectively. The bismuth oxide solution is then added to the bismuth molybdate solution, and the mixture is ultrasonicated for 2-4 hours to obtain a mixed solution. Then, 10-20 ml of acetone is added to the mixed solution, and the mixture is stirred for 12-36 hours. After precipitation, the mixture is dried to obtain the bismuth oxide / bismuth molybdate composite photocatalyst. The concentration of bismuth oxide in the mixture was 6.67 × 10⁻⁶. -6 The concentration of bismuth molybdate is 1.2 × 10 mol / L. -5 mol / L; the volume ratio of the mixed solution to acetone added is 2:

1.

7. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The top plate of the anoxic conversion chamber is inclined, with its highest point connected to the photocatalytic reaction chamber and its lowest point connected to the aerobic separation chamber. A gas collecting pipe is installed at the highest point of the top plate, which is connected to an exhaust pipe for discharging methane gas. A packing hook is installed on the top plate of the anoxic conversion chamber, on which anoxic packing is suspended. A three-phase separator is installed at the outlet of the anoxic conversion chamber. The bottom of the anoxic conversion chamber has a conical structure, and an anoxic conversion chamber discharge valve is installed at the bottom of the conical structure.

8. The photocatalytic treatment device for yellow water according to claim 1, characterized in that, The aerobic separation chamber is equipped with an aerobic separation chamber inlet pipe at the top, an aerobic separation chamber water distributor at the outlet of the aerobic separation chamber inlet pipe, and aerobic packing material at the bottom of the aerobic separation chamber water distributor. An aeration pipe is installed at the bottom of the aerobic packing material to increase the activity of the water. The aerobic filler is made of aldehyde fiber or polyester filament.

9. A method for photocatalytic treatment of yellow water, characterized in that, The photocatalytic treatment device for yellow water, as described in any one of claims 1 to 8, comprises the following steps: ① The wastewater enters the ammonia stripping and collection chamber, a denitrification aid is added, and the pH of the wastewater is adjusted to 8~12; then, the wastewater is kept at 25℃~55℃ for 60min~150min for aeration and gas-liquid separation treatment. The free ammonia in the wastewater is then collected and mixed with sulfuric acid solution to generate ammonium sulfate for reuse. ② Wastewater enters the reaction crystallization chamber, and magnesium, phosphorus, and alkali sources are added to achieve a Mg:K:P molar ratio of 3.3:1:3.

3. Simultaneously, the pH of the wastewater is adjusted to 8-11. The mixture is then stirred to generate magnesium ammonium phosphate, magnesium potassium phosphate, and magnesium sodium sulfate. These substances settle to the sedimentation zone at the bottom of the reaction crystallization chamber under gravity, where they are discharged, dehydrated, dried, and recycled. The magnesium source is MgCl2·H2O, the phosphorus source is Na2HPO4·12H2O, and the alkali source is NaOH. ③ The wastewater enters the columnar adsorption chamber and is filtered and adsorbed sequentially through the lower pebble pad, adsorption packing, and top pebble pad to generate magnesium phosphate and magnesium ammonium phosphate for recycling. ④ The wastewater enters the photocatalytic reaction chamber and circulates alternately through each photocatalytic baffle to degrade the organic pollutants in the wastewater; ⑤ The wastewater enters the anoxic conversion chamber. Under the action of the anoxic packing, the large molecular organic matter in the wastewater is decomposed into small molecular organic matter, and the insoluble organic matter is converted into soluble organic matter. Then, under the action of the three-phase separator, the mud, water and methane gas are separated, and the methane gas is then recovered and reused, while the sludge is discharged. ⑥ The wastewater enters the aerobic separation chamber, where it is filtered and pollutants are removed by aerobic packing material. At the same time, the wastewater is aerated to increase the activity of the water. The treated wastewater is then discharged.

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