Application of sodium tetraphenylborate in carbon sourcing of landfill leachate as well as carbon sourcing method and device

Abstract

The invention discloses application of sodium tetraphenylborate in carbon sourcing of landfill leachate and a carbon sourcing method and device. According to the invention, sodium tetraphenylborate is used as an ammonia nitrogen removing agent and is added into the percolate sewage of the organic garbage, so that the carbon nitrogen ratio of supernatant liquid is increased, and then the supernatant liquid is used as a carbon source. The basic principle that sodium tetraphenylborate is subjected to a precipitation reaction with ammonia ions in an aqueous solution is utilized, then standing separation is selected according to precipitation properties, and discharged water can be stored as a carbon source or directly added into a water treatment process in the form of the carbon source. The precipitate is collected and dehydrated, the precipitate can be recycled as a precipitant after being heated and recovered by alkali liquor, and the released concentrated ammonia gas is collected and can be used for industrial production. The method has the advantages of high reaction efficiency, low interference degree, high controllability of carbon-nitrogen ratio, recyclable main reagents, low theoretical operation cost, obvious removal effect on chroma of sewage, and high industrial value of discharged carbon-sourced water.

Description

[0001] This application is a divisional application of the invention patent with application number 202410403486.7, application date April 3, 2024, and invention title "A method and apparatus for carbon source conversion of organic waste leachate wastewater". Technical Field

[0002] This invention relates to a method and apparatus for carbon source conversion of organic wastewater leachate, and relates to comprehensive wastewater treatment and resource utilization. More specifically, this invention aims to reduce the concentration of ammonium ions in the solution by using sodium tetraphenylborate to precipitate ammonium ions, thereby increasing the carbon-to-nitrogen ratio of the wastewater, significantly improving the bioavailability of organic matter in the wastewater, and promoting the utilization of wastewater as a carbon source. Background Technology

[0003] Urban wastewater treatment plants have high nitrogen and phosphorus discharge standards. In practice, urban wastewater treatment systems face challenges such as large variations in influent water quality, complex water characteristics, high nitrogen and phosphorus content, and a lack of intrinsic carbon sources in the wastewater. This results in a significant demand for carbon source addition during wastewater treatment, especially in denitrification and phosphorus removal processes, which require a high carbon-to-nitrogen ratio and often necessitate sufficient carbon source addition. Currently, the main external carbon sources are small molecule alcohols or acids such as methanol and sodium acetate, as well as glucose. However, these are costly. Based on experience from similar landfill leachate treatment projects, 1 ton of leachate often requires the addition of 4-5 kg ​​of food-grade glucose, costing 5000 yuan per ton. This translates to an additional 20-25 yuan per ton of leachate for carbon source addition. Besides the high cost, fluctuations in influent water quality and the potential for insufficient nitrogen and phosphorus removal due to quantitative carbon source addition can easily lead to reagent waste, increased sludge production, and inadequate nitrogen and phosphorus removal.

[0004] Considering the aforementioned issues with external carbon sources in industrial production, finding low-cost and stable carbon sources is of great significance. Current research indicates that paper and corn cobs, through a series of treatments, can be used as external carbon sources, but their actual stability and utilization efficiency are relatively poor. Another waste resource utilization carbon source, however, is the wastewater from the hydrolysis and acidification of kitchen waste, which has extremely high organic matter concentrations, improving wastewater biodegradability and denitrification efficiency. However, this type of carbon source has a relatively complex chemical composition, making it difficult to control the carbon-to-nitrogen ratio to the target value, resulting in low controllability. Furthermore, residual oils can inhibit denitrification during long-term operation. Summary of the Invention

[0005] This invention addresses the problems of high cost of adding carbon sources for nitrogen and phosphorus removal in wastewater and the difficulty of deep treatment. From the perspective of wastewater resource utilization, it provides a method for carbon source conversion of organic wastewater leachate. This method uses sodium tetraphenylborate to react with ammonium ions to reduce the equimolar amount of ammonia nitrogen in the solution, thereby increasing the carbon-nitrogen ratio of the solution to meet the carbon source utilization standard and promoting its resource utilization.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention provides a method for carbon source conversion of organic landfill leachate wastewater, comprising:

[0008] S1. An aqueous solution of sodium tetraphenylborate is added to the leachate wastewater of organic waste as an ammonia nitrogen removal agent, and the mixture is stirred thoroughly to separate the solid and liquid, resulting in an upper clear liquid and a lower milky white water-containing precipitate.

[0009] S2. The lower layer of milky white water-containing precipitate is removed and dehydrated. The liquid produced by dehydration is combined with the upper clear liquid to form the carbon source required for adjusting the carbon-nitrogen ratio in the wastewater treatment process. The precipitate produced by dehydration is dissolved in an organic solvent, and an excess of strong alkali solution is added for heating and condensation. The organic solvent is recovered from the condensate, and sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates.

[0010] As a preferred embodiment of the first aspect, the dosage of the ammonia nitrogen removal agent should be such that the concentration of precipitate in the mixed system after thorough mixing is between 70 mmol / L and 120 mmol / L.

[0011] As a preferred embodiment of the first aspect above, the solid-liquid separation is achieved by allowing the mixture to stand for 5 to 10 hours.

[0012] As a preferred embodiment of the first aspect above, the organic solvent is acetone.

[0013] As a preferred embodiment of the first aspect above, the strong alkaline solution is an aqueous solution of sodium hydroxide.

[0014] As a preferred embodiment of the first aspect above, the precipitate produced by the dehydration needs to be pre-washed, dried and pulverized before being dissolved in an organic solvent.

[0015] As a preferred embodiment of the first aspect above, during the heating and condensation process, the heating temperature is 60-90°C, and the organic solvent is heated until it is completely evaporated and leaves a precipitate. During the heating and condensation process, the evaporated organic solvent needs to be recovered through a condensation device, the escaped ammonia gas is collected through a tail gas collection device, and finally the sodium tetraphenylborate in the precipitate is collected.

[0016] As a preferred embodiment of the first aspect, after the ammonia nitrogen removal agent is added to the leachate wastewater of organic waste, flocculants and coagulants need to be added to enhance sedimentation.

[0017] As a preferred embodiment of the first aspect mentioned above, the sodium tetraphenylborate used to prepare the aqueous solution of sodium tetraphenylborate has an industrial purity of 99%.

[0018] Secondly, the present invention provides a carbon source conversion device for organic waste leachate, which includes a uniform feeding device, a stirring device, a reaction tank, an overflow sedimentation tank, a buffer tank, a dewatering device, a membrane filtration system, and a storage tank.

[0019] The reaction tank serves as the main body of the reaction, with an inlet and an outlet on its side wall, and a sludge discharge outlet in the sedimentation zone at the bottom.

[0020] The overflow sedimentation tank serves as the main body for secondary sedimentation, with an inlet and an outlet on its side wall, and a sludge discharge outlet in the sedimentation zone at the bottom.

[0021] The uniform feeding device is located above the reaction tank and has multiple discharge holes for uniformly adding an aqueous solution of sodium tetraphenylborate to the leachate wastewater as an ammonia nitrogen removal agent.

[0022] The stirring device is used to fully stir and mix the ammonia nitrogen removal agent and leachate wastewater in the reaction tank;

[0023] The inlet of the reaction tank is used to inject leachate wastewater from organic waste, and the outlet is connected to the inlet of the overflow sedimentation tank. The supernatant that has been preliminarily separated after thorough stirring and mixing in the reaction tank is injected into the overflow sedimentation tank for secondary sedimentation. The supernatant overflowing from the overflow sedimentation tank is sent to the membrane filtration system through the outlet for membrane filtration. The membrane-filtered liquid is sent to the storage tank for temporary storage and is used as a carbon source for adjusting the carbon-nitrogen ratio in the wastewater treatment process.

[0024] The lower layer of milky white water-containing precipitate collected at the bottom of the reaction tank and the overflow sedimentation tank is periodically discharged into the dewatering device through the sludge discharge port. The liquid produced by dewatering is filtered by the membrane filtration system and temporarily stored in the storage tank, while the precipitate produced by dewatering is sent to the heating and condensation recovery device. It is heated and condensed by dissolving in an organic solvent and adding an excess of strong alkali solution. The organic solvent is recovered from the condensate, and sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates.

[0025] As a preferred embodiment of the second aspect above, the dewatering device is a hydrocyclone separator or a plate and frame filter press.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] (1) The present invention adopts the method of treating waste with waste. The leachate wastewater of organic waste with high organic content is transformed into a carbon source with a high carbon-to-nitrogen ratio by adding sodium tetraphenylborate for denitrification and phosphorus removal in wastewater. Compared with methanol, sodium acetate, glucose, etc., the theoretical cost is significantly reduced.

[0028] (2) The wastewater carbon source conversion method provided by the present invention involves fewer reactions, is simple to operate, has strong controllability, reacts rapidly, and the precipitant sodium tetraphenylborate can be recycled, with good recycling effect.

[0029] (3) The wastewater carbon source method provided by the present invention has less impact on the COD value of carbon source wastewater. During the treatment process, it can also remove precipitated impurities and some color in the solution through precipitation adsorption, which fully improves the quality of wastewater as a carbon source. It is better than adding carbon source after hydrolysis and acidification of kitchen waste wastewater and has stronger controllability of carbon-nitrogen ratio. Attached Figure Description

[0030] Figure 1 A schematic diagram illustrating the steps of a method for carbon source conversion of organic waste leachate.

[0031] Figure 2 This is a schematic diagram of a device for carbon source conversion of organic wastewater leachate. 3

[0032] The attached diagram is labeled as follows: 1. Uniform feeding device; 2. Stirring device; 3. Reaction tank; 4. Overflow sedimentation tank; 5. Buffer tank; 6. Dewatering device; 7. Membrane filtration system; 8. Storage tank. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, a detailed description of specific embodiments is provided below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed below. Technical features in the various embodiments of the present invention can be combined accordingly without mutual conflict.

[0034] This invention focuses on the resource utilization of carbon from wastewater. Addressing existing problems, it aims to propose a highly controllable, stable, and low-cost carbon source for waste resource recovery. The target water body is selected based on its high organic matter content and high ammonia nitrogen ratio. The primary goal is to increase the carbon-to-nitrogen ratio of the wastewater by removing ammonium ions through precipitation, thereby improving the wastewater's biodegradability. Based on existing research, there are two main principles for ammonia nitrogen precipitation: one is through the formation of magnesium ammonium phosphate, which removes both ammonium and phosphorus ions; the other is through the precipitation reaction of sodium tetraphenylborate with ammonium ions. The latter has the advantage of being rapid and involving only a single chemical reaction, where ammonium ions replace sodium ions in sodium tetraphenylborate. Furthermore, under alkaline heating conditions, ammonia is released, reducing the sodium tetraphenylborate back to sodium tetraphenylborate. The reaction pathway is simple, and the regeneration cost is low. Therefore, this invention utilizes the precipitation reaction of sodium tetraphenylborate with ammonium ions in aqueous solution as its basic principle. This reduces the equimolar amount of ammonia nitrogen in the solution, increasing the carbon-to-nitrogen ratio to meet the carbon source utilization standard and promoting its resource utilization.

[0035] Example 1

[0036] This embodiment serves as a preliminary experiment to demonstrate the ammonium ion control effect achieved by adding sodium tetraphenylborate to an organic landfill leachate sample before UASB treatment, thereby proving the feasibility of the principle of this invention. The specific experimental procedure of this embodiment is as follows:

[0037] Take a sample containing 2300 mg / L NH4 +Water samples (belonging to organic waste leachate, hereinafter the same) from a certain transfer station of -N before UASB treatment were placed in multiple test tubes, with a total of 6 parallel samples, each group having three replicates. The ratio of the total molar amount of sodium tetraphenylborate added to the total molar amount of ammonia nitrogen in the test tube was 6:5, 1:1, 2:3, 1:2, 1:3, and 1:6. After thorough mixing, the samples were filtered using 0.45-micron microporous filter paper, and the clear liquid in the bottle was taken into test tubes. Among them, the 6:5 and 1:1 experimental groups may have an excess of sodium tetraphenylborate, which may have a certain impact on the determination of ammonia nitrogen concentration by sodium's reagent ultraviolet spectrophotometry. After taking the samples, excess 1 g / L potassium chloride solution was added, the volume of added was recorded, the dilution factor was calculated, and after sufficient precipitation, the samples were centrifuged at 10000 r / min for 2 min before the solution was taken into test tubes. The results of the sodium tetraphenylborate reagent ultraviolet spectrophotometry in this embodiment show that the ammonia nitrogen concentrations at the six ratios were 0 mg / L, 0 mg / L, 455 mg / L, 1136 mg / L, 1535 mg / L, and 1904 mg / L, respectively, with removal rates of 100%, 100%, 80.23%, 50.63%, 33.25%, and 17.23%. Excluding the slight error caused by potassium ions in the solution, the results are basically consistent with the theoretical dosage ratio. This fully demonstrates that in this water sample treatment system, the addition of sodium tetraphenylborate can remove ammonium ions from leachate wastewater in an equimolar amount. Therefore, in practical engineering, the concentration of ammonium ions in the water can be controlled by adjusting the dosage of sodium tetraphenylborate according to actual needs, thereby increasing the carbon-to-nitrogen ratio of the wastewater to meet the carbon-to-nitrogen ratio requirements as a carbon source.

[0038] In addition, for the experimental groups described above in this embodiment, the COD values ​​of the solutions before and after the reaction were measured. After repeated experiments and comparisons, it was found that the COD value of the solution after adding sodium tetraphenylborate precipitation was reduced by about 10% compared to the previous 5900 mg / L. The reduction in COD value was basically the same at multiple sodium tetraphenylborate addition concentrations. Considering several factors such as the presence of some precipitate in the solution and the significant decrease in color of the solution before and after the reaction, the reason for the decrease in COD value may be that the sodium tetraphenylborate precipitation removes colored substances in the solution through adsorption or reaction, and that some COD-containing precipitates in the solution are also removed during the precipitation process.

[0039] Example 2

[0040] This embodiment is used to verify the precipitation separation effect after adding sodium tetraphenylborate aqueous solution to leachate, and two different sets of tests were set up: static precipitation and flocculation precipitation.

[0041] The experimental procedure for the static precipitation method is as follows:

[0042] Take a sample containing NH4 at a concentration of 2300 mg / L. +Water samples from a UASB transfer station in a certain region were collected in multiple test tubes before treatment. A total of 6 parallel samples were set up, with three replicates in each group. The ratio of the total molar amount of sodium tetraphenylborate added to the total molar amount of ammonia nitrogen in the test tube was 6:5, 1:1, 2:3, 1:2, 1:3, and 1:6. After thorough mixing, the corresponding molar concentrations of the precipitate were 164.28 mmol / L, 109.52 mmol / L, 82.14 mmol / L, 54.76 mmol / L, and 27.38 mmol / L. In each experimental group, the precipitation effect of different dosages was investigated using the static precipitation method. After 8 hours of standing, it was clearly found that the supernatant of the solution was the clearest at the 2:3 and 1:2 dosage ratios, similar to the filtration effect of 10-micron pore size filter paper. However, the clarity of the solution decreased with both higher and lower dosages of sodium tetraphenylborate. The experiment showed that the precipitation effect of sodium tetraphenylborate and the precipitation concentration exhibited a trend of first increasing and then decreasing. Further gradient experiments indicated that if static precipitation is to be used to remove the precipitate formed by sodium tetraphenylborate and ammonia nitrogen, the dosage of ammonia nitrogen removal agent should be such that the precipitate concentration in the mixed system after thorough mixing is between 70 mmol / L and 120 mmol / L.

[0043] The experimental procedure for flocculation and sedimentation is as follows:

[0044] Take a sample containing 2300 mg / L NH4 + A water sample from a transfer station in the N region, before UASB treatment, was reacted with an equal volume of 28110 mg / L sodium tetraphenylborate solution. At this point, the NH4+ in the mixed system... + The molar ratio of -N to sodium tetraphenylborate is 2:1, theoretically leaving 1150 mg / L NH4. + Based on multiple experiments, the remaining ammonia nitrogen concentration in the solution was measured to be 1134 mg / L. Adding 100 mg / L polyaluminum chloride and 100 mg / L polyacrylamide resulted in high flocculation efficiency. After 5 hours of settling, the precipitate layer accounted for 42.86% of the total volume, and the supernatant showed high clarity, with turbidity similar to that achieved through 0.45mm filter paper. The suspended solids mass after drying and weighing was also the same. After a total of 14 hours of settling, the precipitate layer accounted for 31.25% of the total volume, and the supernatant remained extremely clear. This indicates that if settling is insufficient to meet the sedimentation requirements after adding ammonia nitrogen removal agents to leachate from organic waste, flocculants and coagulants can be added to enhance sedimentation.

[0045] Example 3

[0046] This embodiment is used to verify the precipitation separation effect of adding sodium tetraphenylborate aqueous solution to permeate and then centrifuging.

[0047] Take a sample containing 2300 mg / L NH4 + A water sample from a transfer station in -N, before UASB treatment, was reacted with an equal volume of 28110 mg / L sodium tetraphenylborate solution to form an aqueous solution. The solution was then centrifuged at speeds of 1000 r / min, 2000 r / min, and 3000 r / min for 20 min, respectively. After centrifugation, the centrifugation effects were compared. The effect of centrifugation at 1000 r / min was similar to that of filtration through 10-micron filter paper. The amount of suspended solids in the solution at 2000 r / min and 3000 r / min was similar to that of passing through 0.45 microporous filter paper, and there was basically no precipitate residue in the solution.

[0048] The sample contained NH4 at a concentration of 2300 mg / L. + A water sample from a transfer station in -N, before UASB treatment, was reacted with an equal volume of 56220 mg / L sodium tetraphenylborate solution to form an aqueous solution. This resulted in an equimolar reaction of ammonium ions with sodium tetraphenylborate. Ten groups were set up, each with three parallel samples. The samples were filtered using 0.45 μm microporous filter paper, 10 μm microporous filter paper, and centrifuged at speeds of 100 r / min, 200 r / min, 400 r / min, 600 r / min, 800 r / min, 1000 r / min, 2000 r / min, and 3000 r / min for 20 min. Comparison of the different centrifugation effects revealed that at speeds of 1000 r / min and below, it was virtually impossible to separate the precipitate. Centrifugation at 2000 r / min significantly increased solution clarity, but the clarity was lower than that achieved with 10 μm microporous filter paper. Centrifugation at 3000 r / min yielded similar results to 10 μm microporous filter paper, indicating the best overall effect.

[0049] This indicates that while centrifugal sedimentation is effective to some extent when the concentration of precipitates generated by sodium tetraphenylborate and ammonia nitrogen is too high, it still falls short of achieving optimal removal performance. When applying the method of this invention, it is still necessary to reasonably control the precipitate concentration. Specifically, the dosage of sodium tetraphenylborate should be determined based on the wastewater volume, the molar concentration of ammonia nitrogen, and the target carbon-to-nitrogen ratio. Ideally, the precipitate concentration in the mixed system should be between 70 mmol / L and 120 mmol / L, at which point the separation effect by static sedimentation is also relatively good. However, if a single addition cannot reduce the carbon-to-nitrogen ratio to the target value, multiple additions can be considered to reduce the concentration of precipitates generated each time.

[0050] Example 4

[0051] This embodiment demonstrates that the carbon source method of the present invention can achieve the regeneration of sodium tetraphenylborate.

[0052] Take 60 mL of NH4 with a concentration of 2300 mg / L +A water sample from a transfer station in -N, before UASB treatment, was reacted with an equal volume of 56220 mg / L sodium tetraphenylborate solution to form an aqueous solution. After drying and weighing with 0.45 μm microporous filter paper and a glass dish, the water sample was filtered through the 0.45 μm microporous filter paper. The precipitate was dried at 80℃ and weighed, with an average mass of 2.1368 g, resulting in a precipitate recovery rate of 64.28%. The precipitate was then ground into powder in a mortar and rinsed with 20 mL of acetone into a ground glass conical flask. 0.5 g of flake sodium hydroxide reagent and 20 mL of deionized water were added and stirred until homogeneous. A spherical condenser was placed above the flask, using air as the condensing fluid. The flask was heated in a sand bath at 100℃ for 4 hours using an electromagnetic heating and stirring furnace. During the heating process, a yellow insoluble substance was released from the white precipitate and suspended in the solution. After heating, the solution was allowed to cool to room temperature, and the acetone was collected by evaporation and condensation. The pH of the water was then adjusted to approximately 7–8, and the solution was added dropwise to a solution containing 2000 mg / L NH4+. + In the N-ammonium chloride solution, the formation of white flocculent precipitate indicates that sodium tetraphenylborate has been successfully regenerated.

[0053] Take 20 mL of NH4 with a concentration of 2300 mg / L + A water sample from a transfer station in N, before UASB treatment, was reacted with an equal volume of 28110 mg / L sodium tetraphenylborate solution. The resulting aqueous solution was centrifuged at 2000 r / min for 20 min. The supernatant was collected by decantation to minimize precipitate loss. Deionized water was then added to wash the precipitate, and the mass of deionized water in each centrifuge tube was balanced. The process was repeated once more. Finally, the supernatant was decanted, and the precipitate was scraped off. The sample was washed with acetone and transferred to a glass dish (pre-weighed and marked). The dish was then dried at 80℃ until it reached equilibrium. The average mass was 0.4736 g, and the recovery rate was 99.53%. The solution was then ground into powder in a mortar and pestle, and then dissolved and rinsed with 20 mL of acetone into a ground glass conical flask. 0.1 g of granular sodium hydroxide reagent and 20 mL of deionized water were added to each group. A magnetic stir bar was added, and the mixture was stirred at 600 r / min for 0.5 h on a magnetic stirrer. After the precipitate was fully dissolved, a small amount of yellow precipitate was still found in the solution. The conical flask was then heated in an 80℃ water bath for 4 h. After the reaction was complete, deionized water was added to bring the liquid volume in the conical flask to 50 mL. The mixture was then sonicated and dissolved evenly, and finally diluted to volume using a 100 mL volumetric flask. Then, 5 mL of a solution containing 2000 mg / L NH4+ was taken. +-N ammonium chloride solution was added to a test tube, and 5 mL of sodium tetraphenylborate solution from a volumetric flask was added to regenerate the sodium tetraphenylborate solution. Three replicates were set up for each group, and a separate group was prepared by adding 5 mL of sodium tetraphenylborate solution for calculating the recovery rate. The above solutions were centrifuged at 2000 rpm for 20 min, and the supernatant was used to determine the ammonia nitrogen concentration using Sodium's reagent ultraviolet spectrophotometry. Simultaneously, 2000 mg / L NH4+ was also determined. + The ammonia nitrogen value of the -N ammonium chloride solution was used to calculate the concentration of sodium tetraphenylborate in the solution, based on the ammonia nitrogen removal rate. The actual recovery rate of sodium tetraphenylborate was found to be 56.18% after the determination.

[0054] Example 5

[0055] This example demonstrates the effects of adding sodium tetraphenylborate to leachate from organic waste at different treatment stages.

[0056] Experiment 1: Using leachate from a landfill, the ammonia nitrogen concentration was measured to be 1128 mg / L NH4. + -N, sodium tetraphenylborate reagent was added at a 1:1 molar ratio. After centrifugation and separation, ammonia nitrogen was found to be almost completely removed, COD concentration was reduced to a certain extent, nitrate nitrogen remained basically unchanged, and the carbon-nitrogen ratio of the water body increased significantly.

[0057] Experiment 2: Using the effluent from the secondary sedimentation tank of a landfill leachate wastewater treatment process, the ammonia nitrogen concentration was measured to be 188 mg / LNH4. + -N, sodium tetraphenylborate reagent was added at a 1:1 molar ratio. After centrifugation and separation, ammonia nitrogen was found to be almost completely removed, COD concentration remained basically unchanged, nitrate nitrogen remained basically unchanged, and the carbon-nitrogen ratio of the water body increased significantly.

[0058] Experiment 3: Using the effluent from the anoxic tank of a landfill leachate wastewater treatment process, the ammonia nitrogen concentration was measured to be 1031 mg / L NH4. + -N, sodium tetraphenylborate reagent was added at a 1:1 molar ratio. After centrifugation and separation, ammonia nitrogen was found to be almost completely removed, COD concentration remained basically unchanged, nitrate nitrogen remained basically unchanged, and the carbon-nitrogen ratio of the water body increased significantly.

[0059] Experiment 4: Using a concentrated water sample from a transfer station, the ammonia nitrogen concentration was determined to be 1191 mg / L NH4. + -N, sodium tetraphenylborate reagent was added at a 1:1 molar ratio. After centrifugation and separation, ammonia nitrogen was found to be almost completely removed, COD concentration was reduced to a certain extent, nitrate nitrogen remained basically unchanged, and the carbon-nitrogen ratio of the water body increased significantly.

[0060] Experiment 5: Using a water sample from the equalization tank of a transfer station, the ammonia nitrogen concentration was measured to be 948 mg / L NH4. +-N, sodium tetraphenylborate reagent was added at a 1:1 molar ratio. After centrifugation and separation, ammonia nitrogen was found to be almost completely removed, COD concentration was reduced to a certain extent, nitrate nitrogen remained basically unchanged, and the carbon-nitrogen ratio of the water body increased significantly.

[0061] In Examples 1 to 5 above, the addition of sodium tetraphenylborate will produce a milky white precipitate with high water content. The liquid portion remaining after solid-liquid separation and the liquid portion produced during further dehydration processes such as filtration and centrifugation of this high water content precipitate have a high carbon-to-nitrogen ratio. Therefore, theoretically, they can all be used as carbon sources for adjusting the carbon-to-nitrogen ratio in wastewater treatment processes.

[0062] Example 6

[0063] In this embodiment, based on the experimental results of Examples 1-5 above, a method for the carbon source conversion of renewable organic landfill leachate is designed, the specific steps of which include:

[0064] S1. Add an aqueous solution of sodium tetraphenylborate as an ammonia nitrogen removal agent to the leachate wastewater of organic waste, and stir thoroughly to carry out solid-liquid separation (solid-liquid separation can be completed by standing for 5-10 hours, or flocculants and coagulants can be added, or centrifugation and membrane filtration can be used to assist in the process), to obtain an upper clear liquid and a lower milky white water-containing precipitate.

[0065] S2. Remove the lower layer of milky white water-containing precipitate for dehydration. The liquid produced by dehydration is combined with the aforementioned upper clear liquid to form the carbon source required for adjusting the carbon-nitrogen ratio in the wastewater treatment process. The precipitate produced by dehydration (preferably pre-washed, dried, and pulverized to improve solubility) is dissolved in an organic solvent (preferably acetone or other organic solvents that can dissolve the precipitate). An excess of strong alkaline solution (preferably an aqueous solution of sodium hydroxide, with the molar amount of sodium hydroxide preferably 1.1 times the molar amount of sodium tetraphenylborate, in appropriate excess) is added for heating and condensation. The organic solvent is recovered from the condensate, and sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates.

[0066] In the above heating and condensation process, the heating temperature is preferably controlled at 60-90℃. Heating can be done by water bath or other means until the organic solvent is completely evaporated and leaves a precipitate. During the heating and condensation process, the evaporated organic solvent needs to be recovered by a condensation device, the escaped ammonia gas is collected by a tail gas collection device, and finally the sodium tetraphenylborate in the precipitate is collected.

[0067] This method utilizes the precipitation reaction between sodium tetraphenylborate and ammonium ions in aqueous solution as its basic principle. Following the precipitation, the mixture is allowed to settle and separate according to its properties. The discharged water can be stored as a carbon source or directly added to water treatment processes. The collected precipitate is dehydrated and recovered via alkaline heating, allowing it to be recycled as a precipitant. The released concentrated ammonia gas can be collected and used in industrial production. This method boasts high reaction efficiency, low susceptibility to interference, high controllability of the carbon-to-nitrogen ratio, recyclable main reagents, low theoretical operating costs, and a significant effect on removing color from wastewater. The discharged carbon-sourced water has high industrial value.

[0068] Meanwhile, this embodiment also relates to an organic waste leachate carbonization device for realizing the organic waste leachate carbonization method, which includes a uniform feeding device 1, a stirring device 2, a reaction tank 3, an overflow sedimentation tank 4, a buffer tank 5, a dewatering device 6, a membrane filtration system 7, and a storage tank 8.

[0069] The reaction tank 3 serves as the main body of the reaction, with an inlet and an outlet on its side wall, and a sludge discharge outlet in the sedimentation zone at the bottom.

[0070] The overflow sedimentation tank 4 serves as the main body for secondary sedimentation, with inlet and outlet ports on its side walls and sludge discharge ports in the sedimentation zone at the bottom. A uniform feeding device 1, located above the reaction tank 3, has multiple discharge holes for uniformly adding an aqueous solution of sodium tetraphenylborate as an ammonia nitrogen removal agent to the leachate wastewater. A stirring device 2 is used to thoroughly mix the ammonia nitrogen removal agent and leachate wastewater in the reaction tank 3. The inlet of the reaction tank 3 is used to inject leachate wastewater containing organic waste, and the outlet is connected to the inlet of the overflow sedimentation tank 4. The supernatant liquid, after initial sedimentation and separation in the reaction tank 3 following thorough mixing, is injected into the overflow sedimentation tank 4 for secondary sedimentation. The supernatant liquid overflowing from the overflow sedimentation tank 4 is sent to the membrane filtration system 7 through the outlet for membrane filtration. The filtered liquid is then sent to the storage tank 8 for temporary storage, serving as a carbon source for adjusting the carbon-to-nitrogen ratio in the wastewater treatment process.

[0071] The lower layer of milky white water-containing precipitate collected at the bottom of reaction tank 3 and overflow sedimentation tank 4 is periodically discharged into dewatering device 6 through sludge discharge port. The liquid produced by dewatering is filtered by the membrane filtration system 7 and temporarily stored in storage tank 8, while the precipitate produced by dewatering is sent to heating and condensing recovery device. It is heated and condensed by dissolving in organic solvent and adding excess strong alkali solution. The organic solvent is recovered from the condensate, and sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates.

[0072] In an embodiment of the present invention, the uniform feeding device 1 can uniformly add sodium tetraphenylborate solution to the aqueous solution from above through multiple channels, which prevents excessive local precipitation and increases the difficulty of stirring. Uniform feeding provides better control over the stirring force and effect of precipitation in the solution.

[0073] In embodiments of the present invention, the stirring device 2 can determine a suitable range of stirring force based on different precipitation effects in the process. The main consideration is the precipitation effect of tetraphenylborate ammonium polymerization. Insufficient stirring can easily lead to poor reaction results, while excessive stirring force can easily cause some flocs to float to the top of the solution, forming a high-viscosity substance that is difficult to settle and handle. Therefore, the stirring force needs to be controlled after the reagent is added. Excessive force will cause some flocs to float to the top of the solution and be difficult to settle.

[0074] In an embodiment of the present invention, the reaction tank 3 mainly carries out the precipitation reaction of sodium tetraphenylborate with ammonium ions and the polymerization precipitation of sodium tetraphenylborate. At the same time, a precipitation collection funnel is set at the bottom to collect the polymerized and precipitated substances in the system.

[0075] In an embodiment of the invention, in the overflow sedimentation tank 4, water containing a large amount of milky white substance enters the sedimentation tank from the reaction tank of device 3, and then sedimentation occurs under dynamic overflow conditions. A large sedimentation funnel is set below for sediment collection. The sedimentation effect is significant when the sedimentation concentration is within the range of 70 mmol / L to 120 mmol / L, and the amount of sediment residue in the supernatant is low. The overflow tank is designed with a sedimentation time of 5 to 10 hours. After sufficient settling, the volume ratio of supernatant to sediment layer is 2:3, and the outlet is set at 0.8 times the height of the overflow tank.

[0076] In an embodiment of the present invention, the water after overflow sedimentation in buffer tank 4 serves as a collection and buffer to prevent the subsequent membrane treatment process from being under too much pressure and unable to continue operating.

[0077] In the embodiments of the present invention, the dewatering device 6 employs a cyclone centrifuge, which collects the precipitated water layer in the collection funnels at the bottom of devices 3 and 4 and performs cyclone treatment to promote solid-liquid separation, further reducing the water content of the precipitate. Simultaneously, the separated liquid is returned to device 5 for collection and further processing. The solids below are collected by centrifugal force, washed, dried, and then subjected to subsequent recovery processing. Of course, according to the results of the aforementioned embodiments, under static stratification conditions, a solid-to-liquid volume ratio between 2:3 and 1:2 is suitable, and centrifugation at 1000–2000 r / min for 20–30 min is sufficient for dewatering. Besides using a cyclone separator, a plate and frame filter press can also be used for the dewatering device 6, both of which can achieve good dewatering results.

[0078] In an embodiment of the present invention, the membrane filtration system 7 is configured with a pore size of 0.45 micrometers or less, and an ultrafiltration membrane is considered. Experiments show that the smallest precipitate particle diameter is greater than 0.45 micrometers, and there is essentially no precipitate residue in the water after passing through the ultrafiltration membrane.

[0079] In an embodiment of the present invention, the storage tank 8 may be a pool or a tank, used to collect water that has passed through the ultrafiltration membrane and store it as a carbon source.

[0080] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. An application of sodium tetraphenylborate, wherein sodium tetraphenylborate is added as an ammonia nitrogen removal agent to leachate wastewater from organic waste to increase the carbon-nitrogen ratio of the supernatant and then serve as a carbon source.

2. The use as described in claim 1, characterized in that, After the sodium tetraphenylborate is added to the leachate wastewater of organic waste, the precipitate is separated and recovered by static sedimentation, flocculation sedimentation or centrifugal sedimentation.

3. The use as described in claim 1, characterized in that, The leachate wastewater from the organic waste includes raw leachate from landfills, effluent from the secondary sedimentation tank during the landfill leachate wastewater treatment process, effluent from the anoxic tank during the landfill leachate wastewater treatment process, concentrated liquid samples from waste transfer stations, or water samples from the equalization tank of waste transfer stations.

4. A method for carbon source conversion of organic landfill leachate based on sodium tetraphenylborate, characterized in that, include: S1. Sodium tetraphenylborate is added to the leachate wastewater of organic waste as an ammonia nitrogen removal agent, and the mixture is stirred and mixed thoroughly to separate the solid and liquid, so as to obtain the upper clear liquid and the lower milky white water-containing precipitate. S2. Remove the lower layer of milky white water-containing precipitate for dehydration treatment. The liquid portion produced by dehydration and / or the upper clear liquid are used as the carbon source required to adjust the carbon-nitrogen ratio in the wastewater treatment process. The precipitate produced by dehydration is dissolved in an organic solvent, and an excess of strong alkali solution is added for heating and condensation. The organic solvent is recovered from the condensate, and sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates. The organic solvent must be a volatile organic solvent that can dissolve the precipitate.

5. The method for carbon source conversion of organic waste leachate as described in claim 4, characterized in that, The sodium tetraphenylborate was added to the leachate wastewater from the organic waste in the form of an aqueous solution.

6. The method for carbon source conversion of organic waste leachate as described in claim 4, characterized in that, The solid-liquid separation is performed using one or more of the following methods: static sedimentation, flocculation sedimentation, or centrifugal sedimentation. Preferably, static sedimentation is performed after adding polyaluminum chloride and polyacrylamide.

7. The method for carbon source conversion of organic waste leachate as described in claim 4, characterized in that, It also satisfies one or more of the following: A), B), C), D), E), F): A) The dosage of the ammonia nitrogen removal agent should be such that the concentration of precipitate in the mixed system after thorough mixing is between 70 mmol / L and 120 mmol / L; B) The solid-liquid separation is achieved by standing for 5 to 10 hours; C) The organic solvent is acetone; D) The strong alkaline solution is an aqueous solution of sodium hydroxide; E) The precipitate produced by the dehydration process needs to be pre-washed, dried, and pulverized before being dissolved in an organic solvent; F) During the heating and condensation process, the heating temperature is 60-90℃. The organic solvent is heated until it is completely evaporated and leaves a precipitate. During the heating and condensation process, the evaporated organic solvent needs to be recovered through a condensation device, and the escaped ammonia gas is collected through a tail gas collection device. Finally, the sodium tetraphenylborate in the precipitate is collected.

8. A carbon source conversion device for organic landfill leachate based on sodium tetraphenylborate, characterized in that, It includes a uniform feeding device (1), a stirring device (2), a reaction tank (3), an overflow sedimentation tank (4), a buffer tank (5), a dewatering device (6), a membrane filtration system (7), and a storage tank (8). The reaction tank (3) serves as the main body of the reaction, with an inlet and an outlet on its side wall, and a sludge discharge outlet in the sedimentation zone at the bottom. The overflow sedimentation tank (4) serves as the main body for secondary sedimentation. It has an inlet and an outlet on its side wall and a sludge discharge outlet in the sedimentation zone at the bottom. The sedimentation time of the overflow sedimentation tank (4) is designed to be 5 to 10 hours. The uniform feeding device (1) is located above the reaction tank (3) and is used to add an aqueous solution of sodium tetraphenylborate as an ammonia nitrogen removal agent to the leachate wastewater. The amount of ammonia nitrogen removal agent added should be such that the concentration of precipitate in the mixed system after thorough stirring is between 70 mmol / L and 120 mmol / L. The stirring device (2) is used to fully stir and mix the ammonia nitrogen removal agent and leachate wastewater in the reaction tank (3); The inlet of the reaction tank (3) is used to inject leachate wastewater from organic waste, and the outlet is connected to the inlet of the overflow sedimentation tank (4). The supernatant that has been preliminarily separated after thorough stirring and mixing in the reaction tank (3) is injected into the overflow sedimentation tank (4) for secondary sedimentation. The supernatant overflowing from the overflow sedimentation tank (4) is sent to the membrane filtration system (7) for membrane filtration through the outlet. The pore size of the membrane filtration system (7) is 0.45 micrometers or less. The liquid after membrane filtration is sent to the storage tank (8) for temporary storage and is used as a carbon source for adjusting the carbon-nitrogen ratio in the wastewater treatment process. The lower layer of milky white water-containing sediment collected at the bottom of the reaction tank (3) and the overflow sedimentation tank (4) is periodically discharged into the dewatering device (6) through the sludge discharge port. The liquid produced by dewatering is filtered by the membrane filtration system (7) and temporarily stored in the storage tank (8), while the sediment produced by dewatering is sent to the heating and condensing recovery device. The organic solvent is recovered from the condensate by dissolving it in an organic solvent and adding an excess of strong alkali solution for heating and condensation. Sodium tetraphenylborate is recovered from the precipitate left after the organic solvent evaporates. The organic solvent must be a volatile organic solvent that can dissolve the precipitate.

9. The organic wastewater leachate carbonization device as described in claim 7, characterized in that, The uniform feeding device (1) has multiple discharge holes, through which sodium tetraphenylborate solution is uniformly added from above into the reaction tank (3).

10. The organic wastewater leachate carbonization device as described in claim 7, characterized in that, It also satisfies one or more of the following: G), H), I): G) The membrane filtration system (7) described above uses an ultrafiltration membrane; H) The organic solvent is preferably acetone; I) The dewatering device (6) adopts a hydrocyclone separator and centrifuges at a speed of 1000-2000 r / min for 20-30 min during dewatering, or a plate and frame filter press is used.

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