Inorganic phosphorus recovery method relying on biological phosphorus removal filter tank and aiming at bioactive filler treatment system

Abstract

The invention discloses an inorganic phosphorus recovery method based on a biological phosphorus removal filter tank for a bioactive filler treatment system, and belongs to the fields of water pollution control, low carbon and resource regeneration. The system is composed of a biological phosphorus removal treatment unit, a phosphorus enrichment and recovery treatment unit and a sewage treatment system sludge flushing phosphorus recovery unit, the characteristics that phosphorus-accumulating bacteria release phosphorus in an anaerobic state and absorb phosphorus in an aerobic condition are fully utilized, a form of re-injection of phosphorus-rich water is adopted, ineffective circulation of phosphorus in the sewage treatment process is blocked, and the phosphorus removal efficiency is improved. The phosphorus-absorbing capacity formed by all phosphorus-accumulating bacteria is used for efficiently removing phosphorus in sewage, the use amount of a carbon source required by phosphorus removal is saved (theoretically, 80% of phosphorus can be saved), released phosphorus is stored in a phosphorus-rich water storage pool, and pure recycling of the phosphorus in the sewage is facilitated.

Description

Technical Field

[0001] This invention belongs to the fields of water pollution control, low carbon and resource regeneration, and specifically relates to an inorganic phosphorus recovery technology based on a biological phosphorus removal filter for a biological active filler treatment system. Background Technology

[0002] Phosphorus is an essential component of living organisms, participating in energy transfer and cell structure formation. However, its natural resources are limited, mainly existing in rocks as phosphate. Because the biochemical cycle of phosphorus is unidirectional and difficult to regenerate, it is considered a non-renewable and scarce resource. Domestic sewage contains large amounts of phosphorus. For a long time, the main purpose of phosphorus removal in domestic sewage treatment has been to control eutrophication of the effluent. Almost all phosphorus removal has been achieved through the discharge of excess sludge, resulting in complete mixing of the removed phosphorus with the excess sludge.

[0003] In recent years, with a growing understanding of the non-renewable nature of phosphorus resources, European countries have begun to prioritize the recovery and utilization of phosphorus from domestic sewage. Germany mandates that all wastewater treatment plants serving a population equivalent of over 50,000 must recover phosphorus from sludge or sludge incineration ash. Similarly, Austria, Poland, and Finland primarily employ technologies involving the drying and incineration of phosphorus-containing waste sludge, recovering phosphorus through the treatment of inorganic ash. However, this process can lead to contamination of the recovered phosphorus with heavy metals and other harmful substances from the waste sludge, potentially causing negative environmental and soil impacts when the recovered phosphorus is reused in agriculture.

[0004] In wastewater treatment, phosphorus removal primarily relies on two technologies: biological and inorganic chemical methods. Biological phosphorus removal utilizes the characteristics of polyphosphate-accumulating bacteria (PACs). Under anaerobic conditions, PACs decompose stored polyphosphates to produce ATP. This ATP then facilitates the active transport of volatile fatty acids from the liquid phase into the cells, synthesizing PHA. Simultaneously, PACs release orthophosphates into the liquid phase. Under aerobic conditions, PACs decompose PHA to produce ATP, "excessively" absorbing orthophosphates from the liquid phase and forming even more polyphosphates. Through this difference between release and absorption, PACs effectively remove phosphorus from wastewater. Chemical phosphorus removal technology utilizes chemical agents to react with inorganic phosphorus in the water, forming insoluble phosphorus-containing inorganic compounds. These insoluble substances settle along with activated sludge in a sedimentation tank, thus removing phosphorus from the water. This chemical process generates a large amount of chemical sludge. Biological phosphorus removal is more complex, requiring PACs in the sludge to react alternately under anaerobic and aerobic conditions. In traditional wastewater treatment processes, phosphorus removal is performed simultaneously with the removal of COD and ammonia nitrogen. This creates a contradiction: ammonia nitrogen removal requires a long sludge age, while phosphorus removal requires a short sludge age. Therefore, traditional wastewater treatment systems struggle to maintain low phosphorus concentrations in the final effluent, necessitating chemical phosphorus removal as an auxiliary process and resulting in large amounts of chemical sludge mixed with the excess sludge. The phosphorus-containing sludge obtained from combined biological and chemical phosphorus removal processes is ultimately mixed with settled sludge and discharged through the excess sludge discharge system. This treatment method means that all removed phosphorus is mixed in with the sludge, making separate recovery and utilization difficult.

[0005] Theoretically, there is a 1:1.25 ratio between anaerobic phosphorus release and aerobic phosphorus uptake by polyphosphate-accumulating bacteria (PABs). This means that for every 0.25 units of phosphorus removed, there is a 1-unit ineffective phosphorus cycle, which requires approximately 20 units of organic carbon source. If, during the anaerobic phosphorus release process, organic carbon source is added, and the released phosphorus is collected and removed from the biological phosphorus removal reactor, then the PPBs, having already released 1.25 units of phosphorus uptake capacity, can directly treat phosphorus-containing wastewater, all of their phosphorus uptake capacity can be used for phosphorus removal from the wastewater. This would block the ineffective phosphorus uptake cycle, theoretically saving 80% of the added organic carbon source while simultaneously achieving phosphorus separation from excess sludge. The high-phosphorus water formed by anaerobic phosphorus release is removed and stored. During the next anaerobic phosphorus release, it is returned to the polyphosphate-accumulating bacteria phosphorus release reactor to continue receiving phosphorus released from the anaerobic process. After receiving phosphorus released by polyphosphate-accumulating bacteria multiple times, high-phosphorus water with even higher phosphorus concentration will be formed. At this time, inorganic phosphorus in the high-phosphorus water can be efficiently recovered by using chemical phosphorus removal agents. This can effectively remove phosphorus from wastewater and recover phosphorus.

[0006] Based on the aforementioned technical approach, this invention establishes a new phosphorus removal process that combines biological phosphorus removal with chemical phosphorus recovery. This approach saves on the addition of organic carbon sources while achieving relatively "pure" recovery of chemically precipitated phosphorus, creating better conditions for the further utilization of phosphorus recovered from wastewater treatment. Summary of the Invention

[0007] This invention innovatively proposes a novel treatment scheme for phosphorus removal from the effluent of a biologically active packing system. The phosphorus removal system consists of a biological phosphorus removal treatment unit, a phosphorus enrichment and recovery treatment unit, and a phosphorus recovery unit for the flushing sludge of the wastewater treatment system. The biological phosphorus removal treatment unit includes: a backwash water tank (2), a backwash water collection tank (3), a first biological phosphorus removal filter (4), and a second biological phosphorus removal filter (5); the phosphorus enrichment and recovery treatment unit includes: a phosphorus-rich water storage tank (6) and a chemical phosphorus recovery tank (7); the phosphorus recovery unit for the flushing sludge of the wastewater treatment system includes: a wastewater treatment system flushing sedimentation tank (8) and a sludge dewatering workshop (9).

[0008] The biological active packing treatment tank (1) is a treatment tank that adopts a comprehensive water treatment process, including four stages connected in sequence: anaerobic hydrolysis acidification, primary denitrification, short-cut nitrification and secondary denitrification. Correspondingly, the biological active packing treatment tank (1) is divided into four parts arranged in sequence. At the same time, the short-cut nitrification stage is equipped with a return pipeline to the primary denitrification stage. The four parts of the biological active packing treatment tank (1) are sequentially filled with hydrolysis acidification embedded biological active packing, denitrification bacteria embedded biological active packing, short-cut nitrification bacteria embedded biological active packing, and denitrification bacteria embedded biological active packing. In the anaerobic hydrolysis acidification stage, large organic molecules in wastewater are degraded into smaller organic molecules, which are easier to treat in subsequent steps. In the primary denitrification stage, denitrifying bacteria use the smaller organic molecules as electron donors to react with nitrate and nitrite nitrogen returned from the next stage of short-cut nitrification, reducing these nitrogen compounds to nitrogen gas and removing them. In the short-cut nitrification stage, ammonia nitrogen in wastewater is oxidized to nitrite nitrogen (90%) and nitrate nitrogen (10%) by short-cut nitrifying bacteria, namely ammonia-oxidizing bacteria. In the secondary denitrification stage, denitrifying bacteria further reduce the remaining nitrite nitrogen and nitrate nitrogen to nitrogen gas, further reducing the nitrogen content in wastewater. Through a series of treatment steps including anaerobic hydrolysis acidification, primary denitrification, short-cut nitrification and secondary denitrification, the biological active packing treatment tank (1) can efficiently remove nitrogen oxides from wastewater and optimize the degradation process of organic matter, thereby improving the overall efficiency of wastewater treatment. Biological phosphorus removal is not considered in the biological active packing treatment tank (1), and the removal of phosphorus in wastewater is carried out by the subsequent phosphorus removal system of the system.

[0009] The system has at least two biological phosphorus removal filters: the first biological phosphorus removal filter (4) and the second biological phosphorus removal filter (5) work in parallel and alternately. The number of filters can be increased appropriately according to actual needs to adapt to different application scenarios. Multiple biological phosphorus removal filters are set in parallel and connected to the effluent of the biological active packing treatment tank (1) via valves. Each biological phosphorus removal filter is connected to an influent oxygenation system, a backwashing system and an organic carbon source addition system. The influent oxygenation system includes a blower (59). The backwashing system includes a backwashing water tank (2), a backwashing water pump (21), a backwashing water collection tank (3), and a blower (59). The organic carbon source addition system includes a static mixer (61), an organic carbon source addition pipe (62), and a phosphorus-rich water pump (63). Each biological phosphorus removal filter is connected to a valve at the top. The door is connected to the blower (59) for aeration and oxygenation. At the same time, the lower part of each biological phosphorus removal filter is connected to the blower (59) through a valve for backwashing aeration. Each biological phosphorus removal filter is equipped with a drain outlet for emptying the water after phosphorus removal. The high phosphorus outlet at the bottom of each biological phosphorus removal filter is connected to the phosphorus-rich water storage tank (6) through a valve. At the same time, the upper part of each biological phosphorus removal filter is equipped with a phosphorus-rich water inlet connected to the phosphorus-rich water storage tank (6) through a valve, a static mixer (61), an organic carbon source dosing pipe (62), and a phosphorus-rich water pump (63) for injecting phosphorus-rich water and organic carbon. Each biological phosphorus removal filter is also connected to the backwash water tank (2) through a valve and a backwash water pump (21). Each biological phosphorus removal filter is also connected to the backwash water collection tank (3) through a valve.

[0010] The effluent from the biological active packing treatment tank (1) is connected to the backwash water tank (2) via a valve. The backwash water tank (2) stores part of the effluent from the biological active packing treatment tank (1). During the backwashing of the corresponding biological phosphorus removal filter, the effluent is pumped into the corresponding biological phosphorus removal filter by the backwash water pump (21).

[0011] The backwash water collection tank (3) is used to collect and treat the sludge-water mixture after backwashing of the corresponding biological phosphorus removal filter, and send its supernatant to the front-end treatment system of the sewage treatment plant. The backwash sludge obtained after sedimentation enters the sludge settling tank (8) of the sewage treatment system. At the same time, the biological active packing treatment tank (1) is connected to the sludge settling tank (8) for the sludge generated from the biological active packing treatment tank (1) to be transported to the sludge settling tank (8). The sludge outlet in the sludge settling tank (8) is connected to the sludge dewatering workshop (9). The supernatant outlet of the sludge settling tank (8) and the dewatering liquid outlet of the sludge dewatering workshop (9) are both connected to the chemical phosphorus recovery tank (7).

[0012] The effluent from the phosphorus-rich water storage tank (6) is connected to the chemical phosphorus recovery tank (7). The chemical phosphorus recovery tank (7) is equipped with a phosphorus removal chemical dosing pipe (71), a phosphorus removal agitator (72), and a screw conveyor (73). The bottom of the chemical phosphorus recovery tank (7) is a conical structure, with the lower end of the screw conveyor (73) located inside the conical structure. The upper end of the screw conveyor (73) extends upwards and out of the chemical phosphorus recovery tank (7). The upper end of the screw conveyor (73) is connected to the phosphorus recovery tank (74) via a phosphorus recovery product collection pipe (76). The phosphorus-rich water storage tank (6) is used to store the phosphorus-rich water after anaerobic phosphorus release from each biological phosphorus removal packing tank.

[0013] Each biological phosphorus removal filter includes a biofilm carrier and filter media. The biofilm carrier can be selected from materials capable of supporting polyphosphate-accumulating bacteria to form a biofilm, such as polyurethane packing, sponge packing, fiber packing, curtain packing, or elastic three-dimensional packing. The filter media can be inorganic mineral materials with filtration function, or organic or macromolecular filter materials such as activated carbon. The biofilm carrier and filter media are combined to form an organic combination of biofilm reaction and filtration function. Alternatively, each biological phosphorus removal filter can be directly constructed using materials that can directly form biological filtration functions, such as granular activated carbon, fiber balls, fiber bundle filter media, or comet-shaped fiber filter media.

[0014] The method for inorganic phosphorus recovery using the above-mentioned apparatus is characterized by comprising the following steps:

[0015] (1) Biological phosphorus removal section

[0016] The effluent from the biologically active packing treatment tank (1) is untreated effluent. After entering the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5), it is aerated and oxygenated, and then enters the filter layer. At this time, the polyphosphate-accumulating bacteria in the filter layer of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) are in an empty tank state after completing the phosphorus release process. The phosphorus-containing effluent from the biologically active packing treatment tank (1) flows into the filter layer of the first biological phosphorus removal filter (4) or the filter layer of the second biological phosphorus removal filter (5) under aeration and aerobic conditions. The process of aerobic biological phosphorus removal and wastewater filtration is completed in the filter layer. As the influent continues to flow in and the filtration continues to discharge, the polyphosphate-accumulating bacteria in the filter layer will continuously absorb phosphorus until they reach a "saturated state". At this time, the aeration of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) is turned off, and the effluent from the biological active packing treatment tank (1) is switched to the second biological phosphorus removal filter (5) or the first biological phosphorus removal filter (4). The first biological phosphorus removal filter (4) or the second biological phosphorus removal filter has reached phosphorus saturation. The water in filter (5) is drained, and then the phosphorus-rich water in the phosphorus-rich water storage tank (6) is injected into the drained first biological phosphorus removal filter (4) or second biological phosphorus removal filter (5). During the injection of phosphorus-rich water, an organic carbon source is added at the same time, and the first biological phosphorus removal filter (4) or second biological phosphorus removal filter (5) is placed in an anaerobic state. Under the anaerobic state, the first biological phosphorus removal filter (4) or second biological phosphorus removal filter (5) filled with phosphorus-rich water completes anaerobic phosphorus release, and the phosphorus-rich water forms high-phosphorus water with a relatively higher concentration. Then the high-phosphorus water is discharged into the phosphorus-rich water storage tank (6) for storage until the polyphosphate-accumulating bacteria in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) are in an empty tank state after completing the phosphorus release process, thus completing one biological phosphorus removal process; the effluent from the biological active packing treatment tank (1) enters the corresponding biological phosphorus removal filter, and then aerobic phosphorus absorption and anaerobic phosphorus release are carried out as one biological phosphorus removal process; the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) alternately cycle to carry out the biological phosphorus removal process.

[0017] The polyphosphate-accumulating bacteria in the filter layer will continuously absorb phosphorus until they reach a "saturation state." This "saturation state" can be determined in advance by experimentally measuring the corresponding flow rate and aeration rate to predict the point at which the effluent phosphorus concentration increases. During operation, the optimal operating conditions of the entire system should be determined based on seasonal variations in effluent phosphorus concentration from the biological filter media treatment tank. The determination of the phosphorus concentration in the dephosphorized effluent should be based on the downstream discharge water conditions and local drainage standards.

[0018] As polyphosphate-accumulating bacteria continue to release phosphorus anaerobically and absorb phosphorus aerobicly, polyphosphate-accumulating bacteria in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) will continue to grow and multiply. When their number reaches a certain level, the filter layer needs to be backwashed to remove excess polyphosphate-accumulating bacteria. The backwashing adopts the form of combined air and water backwashing. The backwash water is the effluent from the biological active packing treatment tank (1) stored in the backwash water tank (2). The air source is provided by the blower (59). The backwash mud-water mixture formed during the backwashing process is collected in the backwash water collection tank (3).

[0019] (2) Phosphorus recovery section

[0020] After the biological phosphorus removal process is carried out in alternating cycles in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5), the phosphorus concentration in the phosphorus-rich water storage tank (6) will gradually increase. When the phosphorus concentration in the phosphorus-rich water reaches a predetermined level (e.g., 200 mg / L), the phosphorus-rich water is introduced into the chemical phosphorus recovery tank (7). In the chemical phosphorus recovery tank (7), chemical phosphorus removal agent is added through the phosphorus removal chemical agent dosing pipe (71), and the phosphorus removal mixer (72) is used to stir it thoroughly to promote the chemical removal reaction of phosphorus. After the reaction is completed, the stirring is stopped and the precipitate is allowed to settle naturally. The precipitated chemical phosphorus precipitate is cleaned and separated by the screw conveyor (73) to obtain "pure" recovered phosphorus. These phosphorus recovery products will be stored in the phosphorus recovery tank (74).

[0021] (3) Phosphorus recovery section of sludge flushing in wastewater treatment system

[0022] The flushing sludge generated from the biological active packing treatment tank (1) and the backwash sludge generated from the backwash water collection tank (3) are transported together to the flushing sludge sedimentation tank (8). After sludge-water separation is completed in the flushing sludge sedimentation tank (8) of the wastewater treatment system, the sludge is transported to the sludge dewatering workshop (9) for dewatering. The dewatered sludge is then transported off-site for treatment. The supernatant separated from the flushing sludge sedimentation tank (8) of the wastewater treatment system and the dewatering liquid from the sludge dewatering workshop (9) will flow together into the chemical phosphorus recovery tank (7) for further chemical phosphorus recovery treatment.

[0023] In terms of operation, the DO in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) should be controlled below 0.2 mg / L under anaerobic conditions, and about 2 mg / L under aerobic conditions, with a hydraulic retention time of more than 40 minutes.

[0024] The first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) adopts a combined air-water backwash. During backwashing, the backwash water tank (2) provides the water required for backwashing, and the backwashing intensity is <8 L / (m). 2 The air required for backwashing is provided by a blower (59), with an air supply intensity of 10~15 L / (m).2 ·s).

[0025] The chemical reagents added to the chemical phosphorus recovery tank (7) can be calcium salts, iron salts, magnesium salts, aluminum salts, etc., with calcium salts being preferred. During the phosphorus recovery reaction in the chemical phosphorus recovery tank (7), the pH is controlled within the range of 8 to 11, the reaction time is not less than 10 minutes, and the sedimentation time is not less than 30 minutes.

[0026] The sewage treatment system (1) flushes the sludge in the sedimentation tank (8) for sedimentation. After sedimentation, the sludge is fed into the sludge dewatering workshop (9), while the supernatant is fed into the chemical phosphorus recovery tank (7) for phosphorus recovery.

[0027] The sludge dewatering workshop (9) dewaters the settled sludge and separates the water. The water content of the dewatered sludge is generally 60%~80%, which facilitates the next step of sludge transportation and disposal. The dewatered water is fed into the chemical phosphorus recovery tank (7) for phosphorus recovery.

[0028] The specific advantages are reflected in the following aspects:

[0029] 1. This system fully utilizes the characteristics of polyphosphate-accumulating bacteria to release phosphorus under anaerobic conditions and absorb phosphorus under aerobic conditions, thus blocking the ineffective cycle of phosphorus during wastewater treatment. All the phosphorus absorption capacity formed by polyphosphate-accumulating bacteria is used for efficient removal of phosphorus from wastewater, saving the amount of carbon source required for phosphorus removal (theoretically saving up to 80%). The released phosphorus is concentrated and stored in a phosphorus-rich water storage tank, which facilitates the next step of efficient chemical precipitation and recovery of phosphorus.

[0030] 2. The phosphorus recovery process is completely separated from the precipitated sludge, with no heavy metals or other harmful substances precipitated. The high-phosphorus water contains only pure inorganic phosphorus, and the high purity of the phosphorus recovery product is conducive to further utilization.

[0031] 3. By using high-concentration phosphorus-containing water for chemical treatment, the dosage of chemical phosphorus removal agents can be significantly reduced, by 46% to 65%. Simultaneously, nearly 80% of the organic carbon source for phosphorus removal can be saved, thereby substantially reducing the cost of chemical inputs in the operating expenses.

[0032] In summary, this system not only optimizes biological treatment technically, but also brings significant energy-saving, emission-reduction, and cost-reduction benefits economically. Attached Figure Description

[0033] Figure 1This is a schematic diagram of the inorganic phosphorus recovery technology based on a biological phosphorus removal filter in a biological active filler treatment system according to the present invention; wherein, 1-biological active filler treatment tank, 2-backwash water tank, 3-backwash water collection tank, 4-biological phosphorus removal filter, 5-biological phosphorus removal filter, 6-phosphorus-rich water storage tank, 7-chemical phosphorus recovery tank, 8-sewage treatment system flushing sludge sedimentation tank, 9-sludge dewatering workshop, 11-inlet pipe of biological active filler treatment tank (1), 12-sewage treatment system flushing sludge discharge pipe of biological active filler treatment tank (1), 13-outlet pipe of biological active filler treatment tank (1), 21-backwash water pump, 22 - Backwash water tank (2) inlet pipe, 23 - Backwash water tank (2) outlet pipe, 31 - Backwash water collection tank (3) inlet pipe, 32 - Backwash water collection tank (3) supernatant outlet pipe, 33 - Backwash water collection tank (3) sludge discharge pipe, 41 - Biological phosphorus removal filter (4) inlet pipe, 42 - Biological phosphorus removal filter (4) backwash water outlet pipe, 43 - Biological phosphorus removal filter (4) backwash inlet pipe, 44 - Biological phosphorus removal filter (4) backwash air supply pipe, 45 - Biological phosphorus removal filter (4) phosphorus-rich water outlet pipe, 46 - Biological phosphorus removal filter (4) outlet pipe, 47 - Biological phosphorus removal filter (4) phosphorus-rich water inlet pipe, 48 - Aeration pipe for filtered water in biological phosphorus removal filter (4), 51- Inlet pipe for biological phosphorus removal filter (5), 52- Backwash water outlet pipe for biological phosphorus removal filter (5), 53- Backwash inlet pipe for biological phosphorus removal filter (5), 54- Backwash air supply pipe for biological phosphorus removal filter (5), 55- Phosphorus-rich water outlet pipe for biological phosphorus removal filter (5), 56- Outlet pipe for biological phosphorus removal filter (5), 57- Phosphorus-rich water inlet pipe for biological phosphorus removal filter (5), 58- Aeration pipe for filtered water in biological phosphorus removal filter (5), 59- Blower, 61- Static mixer, 62- Organic carbon source addition pipe, 63- Phosphorus-rich water pump, 64- Phosphorus-rich water storage tank (6) 65-Phosphorus-rich water supply pipe, 66-Phosphorus-rich water storage tank (6) inlet pipe, 71-Phosphorus removal chemical agent dosing pipe, 72-Agitator, 73-Screw elevator, 74-Phosphorus recovery tank, 75-Chemical phosphorus recovery tank (7) supernatant return pipe, 76-Phosphorus recovery product collection pipe, 81-Sewage treatment system flushing sludge sedimentation tank (8) inlet pipe, 82-Sewage treatment system flushing sludge sedimentation tank (8) supernatant conveying pipe, 83-Sewage treatment system flushing sludge sedimentation tank (8) sludge discharge pipe, 91-Sludge dewatering workshop (9) supernatant conveying pipe, 92-Dewatered sludge external delivery pipe. Detailed Implementation

[0034] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0035] Example 1

[0036] The structure and flowchart used are shown below. Figure 1 .

[0037] The biological active packing treatment tank (1) adopts a comprehensive water treatment process, including four stages: anaerobic hydrolysis acidification, primary denitrification, short-cut nitrification, and secondary denitrification. The biological active packing treatment tank (1) is filled with hydrolysis acidification embedded biological active packing, denitrifying bacteria embedded biological active packing, and short-cut nitrifying bacteria embedded biological active packing. The packing preparation technologies used are respectively derived from "Preparation and application of an anaerobic hydrolysis acidification composite bacteria embedded biological active packing ZL 202010375336.1", "Preparation and application of a denitrification denitrification embedded biological ring active packing ZL202010375312.6" and "Preparation and application of a high accumulation rate short-cut nitrification composite bacteria embedded biological active packing ZL202010375313.0". In the anaerobic hydrolysis acidification stage, large organic molecules in wastewater are degraded into smaller organic molecules, which are easier to treat in subsequent steps. In the primary denitrification stage, denitrifying bacteria use small organic molecules as electron donors to react with nitrate and nitrite nitrogen returned from the next stage of short-cut nitrification, reducing these nitrogen compounds to nitrogen gas and removing them. In the short-cut nitrification stage, ammonia nitrogen in wastewater is oxidized to nitrite nitrogen (90%) and nitrate nitrogen (10%) by ammonia-oxidizing bacteria. In the secondary denitrification stage, denitrifying bacteria further reduce the remaining nitrite nitrogen and nitrate nitrogen to nitrogen gas, further reducing the nitrogen content in wastewater. Through this series of treatment steps, the biologically active packing treatment tank (1) can efficiently remove nitrogen compounds from wastewater and optimize the degradation process of organic matter, improving the overall efficiency of wastewater treatment. Biological phosphorus removal is not considered in the biologically active packing treatment tank (1); phosphorus removal in wastewater is carried out by the subsequent phosphorus removal system.

[0038] Wastewater to be dephosphorized enters the biological phosphorus removal filter (4) through the effluent pipe (13) of the biological active packing treatment tank (1) and the influent pipe (41) of the biological phosphorus removal filter (4), where biological phosphorus removal and filtration are completed. During the influent process, oxygen is supplied through the air supply pipe (48) of the filtered water in the biological phosphorus removal filter (4) and the blower (59). The water after aerobic phosphorus absorption is discharged through the effluent pipe (46) of the biological phosphorus removal filter (4). When the phosphorus removal capacity of the biological phosphorus removal filter (4) reaches saturation, the influent to the biological phosphorus removal filter (4) is stopped, and the effluent from the biological active packing treatment tank (1) enters the biological phosphorus removal filter (5) through the effluent pipe (13) of the biological active packing treatment tank (1) and the influent pipe (51) of the biological phosphorus removal filter (5), where the same biological phosphorus removal and filtration process as the biological phosphorus removal filter (4) is completed, and finally discharged through the effluent pipe (56) of the biological phosphorus removal filter (5). When the phosphorus removal capacity of the biological phosphorus removal filter (5) reaches saturation, the effluent from the biological active packing treatment tank (1) re-enters the biological phosphorus removal filter (4) through the effluent pipe (13) of the biological active packing treatment tank (1) and the influent pipe (41) of the biological phosphorus removal filter (4). At this time, the biological phosphorus removal filter (4) has completed the phosphorus release process, and the system proceeds to the next phosphorus removal cycle. When the biological phosphorus removal filter (5) is receiving water, the biological phosphorus removal filter (4) will stop receiving water and continuously discharge water until it is empty. Subsequently, phosphorus-rich water from the phosphorus-rich water storage tank (6) is injected into the biological phosphorus removal filter (4) through the phosphorus-rich water inlet pipe (47), and organic carbon source is added through the organic carbon source addition pipe (62). The organic carbon source and the high-phosphorus water are mixed in the static mixer (61) set on the phosphorus-rich water supply pipe (64) of the phosphorus-rich water storage tank (6). After the biological phosphorus removal filter (4) is filled with phosphorus-rich water, the water intake is stopped, and the anaerobic state is maintained to release phosphorus. After the biological phosphorus removal filter (4) completes the phosphorus release, the phosphorus-rich water is discharged into the phosphorus-rich water storage tank (6) through the phosphorus-rich water outlet pipe (45) of the biological phosphorus removal filter (4) and the inlet pipe (65) of the phosphorus-rich water storage tank (6). At this time, the biological phosphorus removal filter (4) returns to a state with biological phosphorus removal capacity and is ready for the next cycle. The above process also applies to the biological phosphorus removal filter (5). After its phosphorus removal capacity reaches saturation, the process of emptying the water in the tank, injecting phosphorus-rich water, releasing phosphorus, and emptying the phosphorus-rich water again is repeated. The above process is continuously cyclical to realize the phosphorus removal process of the effluent from the biological active packing treatment tank (1). After completing multiple phosphorus absorption cycles, the biological phosphorus removal filters (4) and (5) will need to be backwashed.

[0039] The backwashing system of the biological phosphorus removal filters (4) and (5) includes a backwash water tank (2), a backwash water collection tank (3), and an air source from a blower (59). The system operates using a combined air and water backwashing method. The backwashing process is generally carried out after the phosphorus release in the biological phosphorus removal filter (4) or (5) is completed and the phosphorus-rich water is drained. The specific backwashing procedure is as follows: After the phosphorus-rich water in the biological phosphorus removal filter (4) or (5) is drained (when backwashing is required), the system starts the combined air and water backwashing. The backwash water is transported to the biological phosphorus removal filter (4) or (5) through the inlet pipe (23) of the backwash water tank (2), while the backwash air is provided by the blower (59) and transported to the biological phosphorus removal filter (4) or (5) through the backwash air supply pipe (44 or 54). The backwashing process lasts for 5 to 8 minutes. The backwash effluent flows into the backwash water collection tank (3) through the backwash effluent pipe (42) or (52). The backwash cement water separation is completed in the backwash water collection tank (3). The resulting supernatant is discharged to the inlet of the sewage treatment system through the supernatant effluent pipe (32) of the backwash water collection tank (3). The settled backwash sludge enters the sewage treatment system flushing sludge sedimentation tank (8) through the sludge discharge pipe (33) of the backwash water collection tank (3) and the inlet pipe (81) of the sewage treatment system flushing sludge sedimentation tank (8).

[0040] During the above continuous cycle, the water in the phosphorus-rich water storage tank (6) is recycled until the phosphorus concentration reaches a predetermined level (e.g., 200 mg / L). At this time, the phosphorus-rich water is discharged to the chemical phosphorus recovery tank (7) through the phosphorus-rich water outlet pipe (66) of the phosphorus-rich water storage tank (6). When the chemical phosphorus recovery tank (7) is full, the phosphorus removal chemical agent is added to the tank through the chemical phosphorus removal agent dosing pipe (71), and the agitator (72) is started to fully agitate the tank water. After the agent reacts fully with the phosphorus-rich water, the agitation is stopped and the sedimentation process begins. The inorganic phosphorus precipitate will gradually settle to the bottom during the sedimentation process. Then, the inorganic phosphorus precipitate is cleaned and separated by the screw conveyor (73) and transported to the phosphorus recovery product collection tank (74) through the phosphorus recovery product collection pipe (76) to complete the phosphorus recovery. The supernatant in the chemical phosphorus recovery tank (7) is returned to the influent part of the main sewage treatment process through the supernatant return pipe (75).

[0041] In the main process of wastewater treatment (1), the flushing sludge generated from the biological active packing treatment tank (1) is transported together to the wastewater treatment system flushing sludge sedimentation tank (8) through the flushing sludge discharge pipe (12) of the biological active packing treatment tank (1) and the backwashing sludge generated from the backwash water collection tank (3) through the sludge discharge pipe (33) of the backwash water collection tank (3). In the wastewater treatment system flushing sludge sedimentation tank (8), after the sludge-water separation is completed, the sludge is transported to the sludge dewatering workshop (9) through the sludge conveying pipe (83) of the wastewater treatment system flushing sludge sedimentation tank (8) for dewatering. The dewatered sludge is then transported off-site for treatment. The supernatant separated in the wastewater treatment system flushing sludge sedimentation tank (8) and the dewatering liquid from the sludge dewatering workshop (9) will flow together into the chemical phosphorus recovery tank (7) for further chemical phosphorus recovery treatment.

[0042] The wastewater influent flow rate is Q: 500 L / h, and the influent phosphorus concentration is 5 mg / L.

[0043] After passing through a biologically activated filler tank, the nitrogen in the wastewater is completely removed.

[0044] 1. Biological phosphorus removal filter (4): hydraulic retention time is 40 min, effective volume is about 335 L;

[0045] 2. Biological phosphorus removal filter (5): hydraulic retention time is 40 min, effective volume is about 335 L;

[0046] 3. Phosphorus-rich water storage tank (6): effective volume approximately 335L;

[0047] 4. Chemical phosphorus recovery tank (7): The hydraulic retention time is 40 min and the effective volume is about 335 L; calcium salt is added to form hydroxyapatite precipitate, and the hydroxyapatite precipitate is cleaned and separated by a spiral elevator (73) and sent to the phosphorus recovery product collection tank (74).

[0048] 5. Sewage treatment system flushing sludge sedimentation tank (8): hydraulic retention time is 60 min, effective volume is 500 L;

[0049] 7. Sludge dewatering workshop (10): After sludge dewatering, the sludge moisture content is about 80%.

[0050] Operational results show that the system maintains stable phosphorus removal and recovery efficiency, with effluent phosphorus concentration below 0.1 mg / L and 98% of phosphorus in the influent being removed and recovered. Compared to traditional activated sludge methods, the system saves 65% on chemical phosphorus removal reagent dosage and reduces excess sludge production by 80%. Because the system avoids ineffective phosphorus recycling found in traditional biological phosphorus removal systems, it saves 71% on the addition of organic carbon sources for phosphorus removal, significantly reducing reagent costs in operation.

Claims

1. An inorganic phosphorus recovery device for a biological active filler treatment system's biological phosphorus removal filter, characterized by The system mainly comprises a biological phosphorus removal treatment unit, a phosphorus enrichment recovery treatment unit, and a sewage treatment system flushing sludge phosphorus recovery unit; the biological phosphorus removal treatment unit comprises a backwashing water pool (2), a backwashing water collecting pool (3), a first biological phosphorus removal filter (4), and a second biological phosphorus removal filter (5); the phosphorus enrichment recovery treatment unit comprises a phosphorus-rich water storage pool (6) and a chemical phosphorus recovery pool (7); and the sewage treatment system flushing sludge phosphorus recovery unit comprises a sewage treatment system flushing sedimentation pool (8) and a sludge dewatering workshop (9); The system comprises at least two biological phosphorus removal filters, i.e., the first biological phosphorus removal filter (4) and the second biological phosphorus removal filter (5), which are connected in parallel and work alternately, and the number thereof can be appropriately increased according to actual needs to adapt to different application scenarios; the plurality of biological phosphorus removal filters are connected in parallel and connected to the biological active filler treatment pool (1) via valves; each biological phosphorus removal filter is connected to a water inlet oxygenation system, a backwashing system, and an organic carbon source adding system; the water inlet oxygenation system comprises a blower (59); the backwashing system comprises the backwashing water pool (2), a backwashing water pump (21), the backwashing water collecting pool (3), and the blower (59); the organic carbon source adding system comprises a static mixer (61), an organic carbon source adding pipe (62), and a phosphorus-rich water pump (63); the upper part of each biological phosphorus removal filter is connected to the blower (59) via a valve for aeration and oxygenation, and the lower part of each biological phosphorus removal filter is connected to the blower (59) via a valve for backwashing aeration; each biological phosphorus removal filter is provided with a drain for draining water after phosphorus removal; the lower part of each biological phosphorus removal filter is connected to the phosphorus-rich water storage pool (6) via a valve, and the upper part of each biological phosphorus removal filter is provided with a phosphorus-rich water inlet connected to the phosphorus-rich water storage pool (6) via a valve, the static mixer (61), the organic carbon source adding pipe (62), the phosphorus-rich water pump (63), and a valve, for injection of phosphorus-rich water and organic carbon; each biological phosphorus removal filter is connected to the backwashing water pool (2) via a valve and a backwashing water pump (21); and each biological phosphorus removal filter is connected to the backwashing water collecting pool (3) via a valve; The outlet of the biological active filler treatment pool (1) is connected to the backwashing water pool (2) via a valve, and the backwashing water pool (2) stores part of the outlet water of the biological active filler treatment pool (1), which is pumped into the corresponding biological phosphorus removal filter by the backwashing water pump (21) during backwashing of the corresponding biological phosphorus removal filter; The backwash water collecting tank (3) is used for collecting and treating the sludge-water mixture after backwashing the corresponding biological phosphorus removal filter, and sending the supernatant thereof to the front-end treatment system of a sewage treatment plant, and the backwash sludge obtained after sedimentation is sent to a sewage treatment system to flush a sludge sedimentation tank (8); meanwhile, the biological active filler treatment tank (1) is connected with the backwash sludge sedimentation tank (8) to flush the backwash sludge generated by the biological active filler treatment tank (1) and send the backwash sludge to the backwash sludge sedimentation tank (8); the sludge outlet of the backwash sludge sedimentation tank (8) is connected with a sludge dewatering workshop (9); and the supernatant outlet of the backwash sludge sedimentation tank (8) is connected with the dewatering liquid outlet of the sludge dewatering workshop (9), and both are connected with a chemical phosphorus recovery tank (7); The outlet of the phosphorus-rich water storage tank (6) is connected with the chemical phosphorus recovery tank (7), the chemical phosphorus recovery tank (7) is provided with a phosphorus removal chemical agent adding pipe (71), a phosphorus removal stirrer (72) and a screw elevator (73), the bottom of the chemical phosphorus recovery tank (7) is in a conical structure, the low end of the screw elevator (73) is located in the conical structure, the high end of the screw elevator (73) extends upward and out of the chemical phosphorus recovery tank (7), and the high end of the screw elevator (73) is connected with a phosphorus recovery product collecting pipe (76) and a phosphorus recovery tank (74).

2. The apparatus of claim 1, wherein The biological active filler treatment tank (1) is a treatment tank adopting a comprehensive water treatment process, which includes four stages of anaerobic hydrolysis acidification, primary denitrification, short-cut nitrification and secondary denitrification connected in sequence, and the biological active filler treatment tank (1) is divided into four parts arranged in sequence, and the short-cut nitrification stage is provided with a backflow pipeline backflowing to the primary denitrification stage; the four parts in the biological active filler treatment tank (1) are sequentially added with hydrolysis acidification embedded biological active filler, denitrification bacteria embedded biological active filler, short-cut nitrification bacteria embedded biological active filler and denitrification bacteria embedded biological active filler; in the anaerobic hydrolysis acidification stage, macromolecular organic matters in the sewage are degraded into small molecular organic matters, which are easier to be treated in the subsequent steps; in the primary denitrification stage, denitrification bacteria use small molecular organic matters as electron donors to react with nitrate nitrogen and nitrite nitrogen backflowing from the short-cut nitrification process, so as to reduce these nitrogen compounds into nitrogen gas and remove them; in the short-cut nitrification stage, ammonia nitrogen in the sewage is oxidized into nitrite nitrogen (90%) and nitrate nitrogen (10%) by short-cut nitrification bacteria, i.e. ammonia oxidation bacteria (AOB); in the secondary denitrification stage, denitrification bacteria further reduce the remaining nitrate nitrogen into nitrogen gas, so as to further reduce the nitrogen content in the sewage; through the series of treatment steps of anaerobic hydrolysis acidification, primary denitrification, short-cut nitrification and secondary denitrification, the biological active filler treatment tank (1) can efficiently remove nitrogen compounds in the sewage, optimize the degradation process of organic matters and improve the overall efficiency of sewage treatment; the biological active filler treatment tank (1) does not consider the problem of biological phosphorus removal, and the phosphorus removal in the sewage is performed by the subsequent phosphorus removal system of the system.

3. The apparatus of claim 1, wherein Each biological phosphorus removal filter includes a biofilm carrier and a filter material, the biofilm carrier can be selected from polyurethane filler, sponge filler, fiber filler, curtain filler, elastic three-dimensional filler and other materials that can support the formation of polyphosphorus bacteria film, the filter material can be selected from inorganic mineral materials with filtering function, or organic or macromolecular filtering materials such as activated carbon, the biofilm carrier and the filter material are combined to form an organic combination of biofilm reaction and filtering function; or each biological phosphorus removal filter directly uses granular activated carbon, fiber ball, fiber bundle filter material, comet-shaped fiber filter material and other materials that can directly form a biological filtration function to establish a biological phosphorus removal filter.

4. Process for the recovery of inorganic phosphorus using the apparatus according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: (1) Biological phosphorus removal part The effluent of the biological active filler treatment tank (1) is not subjected to phosphorus removal treatment, enters the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5), and is then aerated and oxygenated, and then enters the filter layer. At this time, the polyphosphorus bacteria in the filter layer of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) are in an empty tank state after completing the phosphorus release process. The effluent containing phosphorus from the biological active filler treatment tank (1) flows into the filter layer of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5), and completes the process of aerobic biological phosphorus removal and sewage filtration under the condition of aeration and oxygenation in the filter layer. With the continuous inflow of the influent and the continuous discharge of the filtration, the polyphosphorus bacteria in the filter layer will continuously absorb phosphorus to reach a “saturated state”. At this time, the aeration of the filter layer of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) is turned off, and the effluent of the biological active filler treatment tank (1) is switched to the second biological phosphorus removal filter (5) or the first biological phosphorus removal filter (4). The water in the filter layer of the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) that has reached phosphorus saturation is emptied. Subsequently, the phosphorus-rich water in the phosphorus-rich water storage tank (6) is injected into the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) that has been emptied of water. During the injection of the phosphorus-rich water, an organic carbon source is also added. At the same time, the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) is in an anaerobic state. The first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) that is filled with phosphorus-rich water completes anaerobic phosphorus release under the anaerobic state. The phosphorus-rich water forms high-phosphorus water with a relatively higher concentration. Then, the high-phosphorus water is discharged into the phosphorus-rich water storage tank (6) for storage. Until the polyphosphorus bacteria in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) are in an empty tank state after completing the phosphorus release process, the biological phosphorus removal process is completed. The effluent from the biological active filler treatment tank (1) enters the corresponding biological phosphorus removal filter, and then undergoes aerobic phosphorus absorption and anaerobic phosphorus release, which is a biological phosphorus removal process. The first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) alternately circulates to carry out the biological phosphorus removal process. With the continuous anaerobic phosphorus release and aerobic phosphorus uptake of PAOs, the number of PAOs in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) will increase and breed, and when the number reaches a certain degree, the filter layer needs to be backwashed to remove the excess PAOs; the backwashing adopts the form of air and water combined backwashing, the backwashing water is the effluent of the biological active filler treatment tank (1) stored in the backwashing water tank (2), and the air source is provided by the air blower (59); the backwashing sludge-water mixture formed in the backwashing process is collected into the backwashing water collection tank (3); (2) Phosphorus recovery part After the biological phosphorus removal process is performed for multiple times by the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) alternately, the phosphorus concentration in the phosphorus-rich water accumulated in the phosphorus-rich water storage tank (6) will gradually increase, and when the phosphorus concentration in the phosphorus-rich water reaches a predetermined level (for example, 200 mg / L), the phosphorus-rich water is introduced into the chemical phosphorus recovery tank (7); in the chemical phosphorus recovery tank (7), a chemical phosphorus removal agent is added through the phosphorus removal chemical agent adding pipe (71), and a phosphorus removal stirrer (72) is used for sufficient stirring to promote the chemical removal reaction of phosphorus, after the reaction is completed, the stirring is stopped, and the precipitate is allowed to settle naturally; the precipitated chemical phosphorus precipitate is cleaned and separated by the screw elevator (73), and "pure" recovered phosphorus is obtained, and these phosphorus recovery products are stored in the phosphorus recovery tank (74); (3) Washing sludge phosphorus recovery part of the sewage treatment system The washing sludge generated by the washing of the biological active filler treatment tank (1) and the backwashing sludge generated by the backwashing sludge collection tank (3) are transported together to the washing sludge sedimentation tank (8); after the separation of sludge and water in the washing sludge sedimentation tank (8) of the sewage treatment system, the sludge is transported to the sludge dewatering workshop (9) for dewatering, and the dewatered sludge is transported out for treatment; the supernatant separated from the washing sludge sedimentation tank (8) and the dewatered liquid from the sludge dewatering workshop (9) are jointly flowed into the chemical phosphorus recovery tank (7) for further treatment of chemical phosphorus recovery.

5. The method of claim 4, wherein, In terms of operation, the DO in the first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) should be controlled to be below 0.2 mg / L under anaerobic conditions and about 2 mg / L under aerobic conditions, and the hydraulic retention time is greater than 40 minutes.

6. The method of claim 4, wherein, The first biological phosphorus removal filter (4) or the second biological phosphorus removal filter (5) adopts air and water combined backwashing, and the water required for backwashing is provided by the backwashing pool (2), and the backwashing intensity is <8 L / (m 2 ·s); the air required for backwashing is provided by the air blower (59), and the air supply intensity is 10~15 L / (m 2 ·s).

7. The method of claim 4, wherein, The chemical agent added in the chemical phosphorus recovery tank (7) can be selected from calcium salt, iron salt, magnesium salt, aluminum salt, etc., and the calcium salt is preferred; the pH in the chemical phosphorus recovery tank (7) is controlled to be in the range of 8-11 during the phosphorus recovery reaction, the reaction time is not less than 10 minutes, and the precipitation time is not less than 30 minutes.

8. The method of claim 4, wherein, In the washing sludge sedimentation tank (8) of the sewage treatment system, the sludge is settled, and after the settlement, the sludge is transported to the sludge dewatering workshop (9), and the supernatant is transported to the chemical phosphorus recovery tank (7) for phosphorus recovery.

9. The method of claim 4, wherein, The sludge dewatering workshop (9) dewatered the settled sludge to separate the water, and the dewatered sludge generally has a water content of 60%-80%, which is convenient for the next step of sludge transportation and disposal; the dewatered sewage is transported to the chemical phosphorus recovery tank (7) for phosphorus recovery.

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