Method for removing phosphorus and recovering phosphorus by enriching and culturing glycogen-accumulating bacteria enhanced biological membrane

Abstract

The invention belongs to the technical field of sewage resource recovery, and particularly relates to a method for removing phosphorus and recovering phosphorus by enriching and culturing a glycogen-accumulating bacterium enhanced biological membrane. The invention provides a method for rapid enrichment culture of Candidate Compatible, which comprises the following steps: enhancing the adhesion growth of the Candidate Compatible in a biofilm culturing stage, regulating a process operation mode after sludge discharge to stimulate the proliferation of the Candidate Compatible and secrete EPS and AHLs, and promoting phosphorus absorption and release of biofilm phosphorus-accumulating bacteria cells and the Candidate Compatible EPS so as to improve the phosphorus removal and recovery capacity of the biofilm. EPS phosphorus absorption and release belong to an adsorption effect under physical and chemical effects, so that the EPS phosphorus absorption and release do not need to consume a carbon source. Therefore, on one hand, the time is shortened, the cost is saved, and on the other hand, low-carbon high-efficiency sewage phosphorus recovery of the biofilm process is ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage resource recovery, and particularly relates to a method for phosphorus removal and recovery by enriching and culturing glycan bacteria to strengthen a biofilm. BACKGROUND

[0002] The biofilm process based on phosphorus recovery realizes simultaneous phosphorus removal and recovery through the combined action of phosphorus accumulating organisms (PAOs) and extracellular polymeric substances (EPS) in the process of phosphorus adsorption and release. The adsorption and release of phosphorus by EPS accounts for a dominant position (68%-97%) in the adsorption and release of phosphorus by the biofilm. It is found that Candidatus Competibacter has the strongest EPS secretion capacity in the biofilm process based on phosphorus recovery. Rapid enrichment and cultivation of high content of Candidatus Competibacter helps to increase the content of EPS of the biofilm, and thus realizes the simultaneous phosphorus removal and recovery capacity of the strengthened biofilm.

[0003] The existing method for enriching and cultivating glycan bacteria is often through: (1) directly enriching and cultivating glycan bacteria; adopting a sequencing batch reactor or a continuous flow reactor, inoculating sludge from a sewage treatment plant, using sodium acetate as the only carbon source, limiting the phosphorus concentration of the influent and / or discharging anaerobic effluent, adjusting the appropriate operation mode to acclimate the activated sludge, and the required time is about 39-90 days. (2) Inhibiting the growth of phosphorus accumulating bacteria and promoting glycan bacteria to be dominant; adopting a sequencing batch reactor, inhibiting the growth and reproduction of phosphorus accumulating bacteria by pumping phosphorus-free influent into the main stream or side stream process, and then adding carbon source for anaerobic stirring and discharging supernatant, and then pumping the water into the water distribution system, entering the aerobic stage, and enriching and cultivating glycan bacteria through multiple aerobic / anaerobic operation cycles. (3) Adjusting the process operation conditions such as carbon source type, temperature, hydraulic condition, sludge age (SRT), pH, P / C, etc. to be suitable for the growth conditions of GAOs, and enriching and cultivating glycan bacteria. The existing method has the problems of long enrichment time, complicated operation, and the enriched glycan bacteria are often used for deep denitrification and organic matter removal, and there is less research on the enrichment and cultivation of glycan bacteria contributing to phosphorus removal and recovery.

[0004] The content of Candidatus Competibacter is closely related to the phosphorus removal and recovery efficiency of the biofilm process based on phosphorus recovery. Rapid enrichment and cultivation of glycan bacteria Candidatus Competibacter with AHLs and EPS secretion capacity is an important way to improve the economic efficiency of the biofilm process for phosphorus removal and recovery.

[0005] The current enrichment culture of glycan bacteria has the following disadvantages: (1) most of the current research is directed to the functional population of glycan bacteria, without involving glycan bacteria Candidatus Competibacter with AHLs and EPS secretion capacity; (2) limiting or not containing the phosphorus concentration of aerobic influent, reducing the carbon source concentration / changing the carbon source type, and combining with various process operation conditions suitable for the growth of glycan bacteria such as pH, hydraulic retention time, temperature, sludge age, etc. are commonly used methods, but the enrichment culture conditions are not designed from the perspective of stimulating glycan bacteria Candidatus Competibacter to secrete EPS and AHLs; (3) the primary difference between biofilm process and activated sludge is that microorganisms grow attached to the filler, and glycan bacteria Candidatus Competibacter can secrete EPS to help them adhere to the filler more than other microorganisms. The current enrichment culture method does not involve strengthening the adhesion of glycan bacteria Candidatus Competibacter to the filler, and then expanding the culture after screening glycan bacteria; (4) the starting point of the current enrichment culture of glycan bacteria is mostly deep denitrification and removal of organic matter, etc., and the enrichment culture is not from the perspective of glycan bacteria secreting EPS, EPS playing a dominant role in the absorption and release of phosphorus by biofilm. SUMMARY

[0006] In order to solve the technical problems existing at present, the application provides the following technical solutions:

[0007] A method for rapidly enriching and culturing glycan bacteria to strengthen biofilm phosphorus removal and phosphorus recovery, which is composed of a biofilm formation stage and a sludge discharge and post-sludge discharge stage;

[0008] The biofilm formation stage comprises the following steps:

[0009] S11: adding activated sludge and aerobic sewage A containing phosphate and N-acyl homoserine lactone (AHLs) into the main reactor containing suspended filler, and discharging the liquid after 2-3h of aerobic treatment; the activated sludge contains polyphosphorus bacteria and glycan bacteria Candidatus Competibacter;

[0010] S12: adding water, carbon source and anaerobic phosphate recovery liquid in the recovery tank into the main reactor, and discharging the liquid into the recovery tank after 1-2h of anaerobic treatment; during the anaerobic treatment, the concentration of carbon source in the main reactor is maintained at 100-200mg / L; the anaerobic water composition in the biofilm formation stage: 100-200mg / L sodium acetate and tap water in the first cycle, and 100-200mg / L of sodium acetate is supplemented in each subsequent cycle, and the anaerobic phosphate recovery liquid is recycled until the enrichment culture ends.

[0011] S13: repeating steps S11 and S12 until the thickness and adhesion of the biofilm increase by no less than 50% compared with 24 hours ago, entering the sludge discharge and post-sludge discharge stage; the biofilm is obtained by microorganisms in the activated sludge gathering on the suspended filler;

[0012] The sludge discharge and post-sludge discharge stage comprises the following steps:

[0013] S21: discharging the activated sludge in the main reactor, adding the aerobic sewage B, discharging the sewage in the main reactor after aerobic treatment for 3-4 hours; the concentration of the phosphate in the aerobic sewage B is 45-55% of the concentration in the aerobic sewage A; except that the concentration of the phosphate in the aerobic influent and the concentration of the carbon source in the anaerobic influent are halved and the AHLs are not added, the other components of the aerobic influent and the anaerobic influent are consistent with those in the biofilm formation stage.

[0014] S22: adding water, a carbon source and the anaerobic phosphate recovery liquid in the recovery tank into the main reactor, discharging the sewage into the recovery tank after anaerobic treatment for 1-2 hours; the concentration of the carbon source is 45-55% of the concentration of the carbon source in the biofilm formation stage;

[0015] S23: repeating steps S21 and S22 until the concentration of the phosphate in the recovery tank is constant.

[0016] The time required from the biofilm formation to the constant concentration of the phosphate in the recovery tank is recorded, that is, the time required for the enrichment culture of the glycogen-accumulating organisms. At the same time, the phosphorus absorption and release content, the chemical oxygen demand (COD) consumption of the biofilm are measured when the enrichment culture is completed, the phosphorus removal efficiency and the recovery liquid concentration are obtained, and the Candidatus Competibacter content, the biomass and the AHLs content of the glycogen-accumulating organisms are measured by taking a proper amount of the biofilm.

[0017] Preferably, the activated sludge is from the secondary sewage treatment (A2O) process secondary sedimentation tank of a sewage treatment plant, and the sludge concentration is no less than 8000 mg / L.

[0018] Preferably, in the activated sludge, the relative abundance of the polyphosphorus bacteria is no less than 2%, and the relative abundance of the glycogen-accumulating organisms Candidatus Competibacter is no less than 0.5%.

[0019] Preferably, in steps S11 and S21, the reactor influent flow is 750-850 mL / min, and the influent time is 5-10 min.

[0020] Preferably, in step S11, the filling ratio of the suspended filler is 30-40%.

[0021] Preferably, in steps S11 and S21, stirring and aeration are performed during aerobic treatment.

[0022] Further, in the step S11, the dissolved oxygen concentration during the aerobic treatment is 5-6 mg / L; and in the step S21, the dissolved oxygen concentration during the aerobic treatment is 7-8 mg / L.

[0023] Preferably, in the biofilm formation stage, sludge discharge stage and post-sludge discharge stage, the pH value in the main reactor during the aerobic stage and the anaerobic stage is 7-7.5.

[0024] Preferably, the aerobic wastewater A comprises 5-10 mg / L of KH2PO4, 280-320 mg / L of NaHCO3, 35-45 mg / L of NH4Cl, 6-10 mg / L of CaCl2·2H2O, 25-35 mg / L of MgSO4·7H2O, 1-3 mg / L of EDTA·2Na, and 0.1-1.0 μM of N-acyl homoserine lactone (AHLs).

[0025] Preferably, the main reactor in the biofilm formation stage is stirred at a speed of 40-50 rpm, and the main reactor in the sludge discharge stage and post-sludge discharge stage is stirred at a speed of 60-70 rpm.

[0026] Preferably, the N-acyl homoserine lactone (AHLs) is selected from one or more of N-butyryl-L-homoserine lactone (C4-HSL), N-hexanoyl-L-homoserine lactone (C6-HSL), N-octanoyl-L-homoserine lactone (C8-HSL), and N-3-oxo-decanoyl-L-homoserine lactone (3OC10-HSL).

[0027] Preferably, the carbon source is sodium acetate.

[0028] Specifically, the method for rapidly enriching and culturing Glycocyclus aequatorialis to strengthen biofilm phosphorus removal and phosphorus recovery comprises the following steps:

[0029] The biofilm process device based on phosphorus recovery is shown in Figure 1 The system comprises a 10 L main reactor (in which the suspended filler filling ratio is 30-40%, the material is Kaldnes K1 polyethylene, the diameter is 15 mm, the height is 5 mm, and the average specific surface area is 900 m 2 / m 3The system consists of a 150L aerobic synthetic wastewater tank, a 20L recovery tank and a 4L anaerobic carbon source tank. In the aerobic stage, the wastewater flows into the main reactor from the aerobic synthetic wastewater tank under the action of gravity, the aeration device provides an aerobic environment, the magnetic stirrer is turned on to make the water quality uniform, and the valve is closed after the actual inflow reaches 8L. After the aerobic stage is completed, the aeration device is turned off, and the wastewater is discharged by opening the pump. The system switches to the anaerobic stage, and the anaerobic influent and sodium acetate in the anaerobic carbon source tank are pumped into the main reactor at the same time, and the anaerobic effluent flows back to the anaerobic phosphate recovery liquid recovery tank through the pump.

[0030] In the biofilm formation stage, activated sludge (sludge concentration not less than 8000mg / L) from the A2O process secondary sedimentation tank of a wastewater treatment plant is added, which contains polyphosphorus bacteria and Candidatus Competibacter. Under the condition of low stirring speed (40-50rpm), aerobic (2-3h) / anaerobic (1-2h) HRT, the aerobic stage is aerated (5-6mg / L) without carbon source, and the biofilm absorbs the phosphate in the wastewater; In the anaerobic stage, only stirring and adding carbon source are carried out, and the anaerobic influent is mixed and introduced into the main reactor, and the biofilm releases the accumulated phosphate in the body into the phosphate recovery liquid; Next, the anaerobic phosphate recovery liquid is recycled every cycle. The biofilm thickness is measured every day using atomic force microscopy and fluorescence inverted microscope, and the sludge is discharged when the biofilm thickness and adhesion force increase by ≥50% compared with the previous day.

[0031] After sludge discharge, the stirring speed is increased to 60-70rpm, the phosphorus concentration of the aerobic influent and the carbon source concentration of the anaerobic carbon source are halved, the dissolved oxygen concentration is increased to 7-8mg / L, the aerobic HRT is extended to 3-4h, and the operation mode is consistent with that in the biofilm formation stage, until the phosphate concentration in the anaerobic enrichment tank no longer increases, that is, the enrichment culture of Candidatus Competibacter is completed.

[0032] Based on the phosphorus recovery of the biofilm process, the polysaccharide bacteria Candidatus Competibacter can secrete a large amount of EPS and N-acyl homoserine lactones (AHLs), and AHLs can promote the secretion of EPS by microorganisms. On the one hand, the secreted EPS helps the microorganisms to adhere to the filler to accelerate the acclimation and start-up of the biofilm process. On the other hand, the increase of the EPS content has more phosphorus storage and release sites, which improves the physical and chemical adsorption / desorption of the biofilm EPS. At the same time, AHLs can promote the phosphorus absorption / release of the polyphosphorus bacteria, which is beneficial to the biological absorption / release of the biofilm polyphosphorus bacteria. In general, the enrichment culture of a higher content of polysaccharide bacteria Candidatus Competibacter can strengthen the phosphorus removal and recovery of the biofilm. Therefore, the present application first adds a large amount of AHLs in the biofilm, promotes the secretion of EPS by polysaccharide bacteria Candidatus Competibacter under aerobic high-concentration phosphate and anaerobic high-concentration sodium acetate, and the sludge is discharged when the biofilm thickness and adhesion rate increase by more than 50% compared with the previous day. After the sludge is discharged, the phosphorus concentration of the aerobic influent and the carbon source concentration of the anaerobic influent are halved, the dissolved oxygen is increased, the aerobic aeration time is prolonged, the high-concentration phosphate recovery liquid is recycled in the anaerobic process, the secretion of AHLs and EPS by polysaccharide bacteria is promoted, and the growth of polysaccharide bacteria is accelerated, so as to realize the purpose of rapid enrichment culture of polysaccharide bacteria Candidatus Competibacter. Studies have shown that when the concentration of the phosphorus recovery liquid is greater than or equal to 50 mg / L, it has the economic feasibility of recovering phosphorus products by struvite method, and the higher the concentration of the phosphorus recovery liquid, the lower the cost of recovering phosphorus. The present application promotes the secretion of EPS and AHLs by polysaccharide bacteria Candidatus Competibacter to strengthen the absorption / release of PAOs cells and EPS, shortens the enrichment culture time, and increases the concentration of the phosphate recovery liquid, thereby reducing the cost of the process.

[0033] The technical solution of the present application has the following advantages compared with the prior art:

[0034] The present application provides a method for rapid enrichment culture of polysaccharide bacteria Candidatus Competibacter, which promotes the adhesion and growth of polysaccharide bacteria Candidatus Competibacter in the biofilm stage, and regulates the process operation mode after sludge discharge to stimulate the proliferation of polysaccharide bacteria Candidatus Competibacter and the secretion of EPS and AHLs, so as to promote the absorption / release of the biofilm polyphosphorus bacteria cells and polysaccharide bacteria EPS, and improve the phosphorus removal and recovery capacity of the biofilm. Since the EPS absorption / release belongs to the adsorption under the action of physical and chemical effects, the EPS absorption / release does not need to consume carbon source. Therefore, the present application shortens the time and saves the cost on the one hand, and ensures the low-carbon and high-efficiency of the biofilm process for wastewater phosphorus recovery on the other hand. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 This is a diagram of the reactor apparatus of the present invention.

[0036] Explanation of reference numerals in the attached drawings: 1-valve, 2-first pump, 3-second pump, 4-third pump, 5-fourth pump, 6-aerobic synthesis wastewater tank, 7-recovery tank, 8-magnetic stirrer, 9-data acquisition device, 10-data logger, 11-aeration device, 12-main reactor, 13-anaerobic carbon source tank. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0038] Example 1:

[0039] 1. Process operating equipment and operation process

[0040] Biofilm process devices based on phosphorus recovery, such as Figure 1 As shown, the system consists of a 10L main reactor 12 containing suspended packing material (suspended packing material filling ratio of 30%, material Kaldnes K1 polyethylene, diameter 15mm, height 5mm, average specific surface area 900m²). 2 / m 3 The system consists of a 150L aerobic synthesis wastewater tank 6, a 20L recovery tank 7, and a 4L anaerobic carbon source tank 13. During the aerobic stage, valve 1 is opened, and wastewater flows from the aerobic synthesis wastewater tank 6 into the main reactor 12 under gravity. Aeration device 11 provides the aerobic environment, and magnetic stirrer 8 is turned on to homogenize the water quality. After the actual influent reaches 8L, valve 1 is closed. After the aerobic stage ends, aeration device 11 is turned off, and the fourth pump 5 is turned on to discharge the wastewater. The system then switches to the anaerobic stage. The first pump 2 and the third pump 4 simultaneously pump the anaerobic influent and sodium acetate from the anaerobic carbon source tank 13 into the main reactor 12. The anaerobic effluent flows back to the recovery tank 7 via the second pump 3.

[0041] In the biofilm formation stage, activated sludge (sludge concentration 8000 mg / L) containing polyphosphorus bacteria and Candidatus Competibacter in the secondary sedimentation tank of an A2O process of a sewage treatment plant is added; the relative abundance of polyphosphorus bacteria is 2.05%, and the relative abundance of Candidatus Competibacter is 0.78%. The repeated alternating operation is repeated under the conditions of low stirring speed (40 rpm), 2 h of aerobic stage and 1 h of anaerobic stage, and the HRT is 3 h. In the aerobic stage, aeration (5 mg / L) is not added with carbon source, and the biofilm absorbs the phosphate in the sewage; in the anaerobic stage, only stirring is added and the carbon source is mixed with the anaerobic influent and then introduced into the main reactor 12, and the biofilm releases the accumulated phosphate in the body into the phosphate recovery liquid; the anaerobic phosphate recovery liquid is used in the next cycle. The biofilm thickness is measured every day using an atomic force microscope and a fluorescence inverted microscope, and the sludge is discharged when the biofilm thickness and adhesion force increase by ≥50% compared with the previous day.

[0042] The sludge is discharged when the biofilm thickness and adhesion force increase by ≥50% compared with the previous day. Candidatus Competibacter secretes a large amount of EPS and adheres to the filler, which has a significant change process. By detecting the changes of biofilm thickness and adhesion in situ, the adhesion of Candidatus Competibacter is determined without damage. Candidatus Competibacter is in a mixed bacterial flora, and there is a complex process of signal exchange and material exchange between microorganisms, mutual dependence and competition. Therefore, it is more beneficial to the growth and proliferation of Candidatus Competibacter after sludge discharge when the adhesion content of Candidatus Competibacter is relatively high, so the enrichment culture time is shorter.

[0043] After the sludge is discharged, the stirring speed is increased to 60 rpm, the phosphate concentration of the aerobic influent and the carbon source concentration of the anaerobic influent are halved to 2.5 mg / L and 50 mg / L respectively, the dissolved oxygen concentration is increased to 7 mg / L, the aerobic hydraulic retention time (HRT) is extended to 3 h, and the operation mode is consistent with that in the biofilm formation stage, until the phosphate concentration in the recovery tank 7 no longer increases, that is, the enrichment culture of Candidatus Competibacter is completed.

[0044] The first anaerobic influent is 100-200 mg / L sodium acetate and tap water, and the anaerobic influent is recycled and supplemented with 50-100 mg / L of carbon source until the anaerobic phosphorus recovery liquid reaches the highest completion of the enrichment culture of Candidatus Competibacter. The trace metal ions in tap water are beneficial to supplement the nutritional needs of biofilm microorganisms, and the carbon source in the anaerobic stage is properly matched with the phosphorus in the aerobic influent. The higher the phosphorus in the influent, the higher the carbon source concentration in the anaerobic stage. This ensures the growth of microorganisms and does not waste carbon source, which is more economical and effective. The recycling of anaerobic phosphorus recovery liquid creates a high-phosphorus environment, which stimulates the secretion of AHLs by biofilm on one hand, and realizes the enrichment and recovery of phosphate on the other hand, avoiding the sludge-water separation problem faced by activated sludge enrichment and recovery of phosphorus, and the operation is more simple.

[0045] After sludge discharge, Candidatus Competibacter does not rely on the decomposition of polyphosphorus for energy supply like polyphosphorus bacteria. It mainly relies on the decomposition of PHA (polyhydroxyalkanoate) for energy supply in the anaerobic stage. Compared with the synthesis of polyphosphorus, the synthesis of PHA requires more time, so extending the HRT of the aerobic stage after sludge discharge is beneficial to the synthesis of more sufficient PHA by Candidatus Competibacter for energy supply, and thus promotes the growth of Candidatus Competibacter.

[0046] The low stirring speed of 40-50 rpm is used in the biofilm formation stage, and the stirring speed is increased to 60-70 rpm after sludge discharge. The low stirring speed in the biofilm formation stage is beneficial to the adhesion and growth of Candidatus Competibacter, and the rapid growth of the adhesion and growth Candidatus Competibacter requires more and richer nutrients after sludge discharge. Increasing the stirring speed makes the nutrients more evenly mixed and more fully contacted with the biofilm, which is beneficial to the uptake of nutrients by Candidatus Competibacter and rapid growth.

[0047] 2. Process Influent Components

[0048] The aerobic and anaerobic influents are synthetic wastewater, and sodium acetate is used as the carbon source. The influent flow rate of the main reactor 12 is 800 mL / min, and the influent time is 5-10 min. The dissolved oxygen (DO) in the aerobic period of the biofilm formation stage is controlled at 5 mg / L, and the pH is 7.0-7.5. The pH in the anaerobic period of the biofilm formation stage is 7.0-7.5. The DO in the aerobic period after sludge discharge is controlled at 7 mg / L, and the pH is 7.0-7.5. The pH in the anaerobic period after sludge discharge is 7.0-7.5.

[0049] Before sludge discharge, because of the symbiotic state of activated sludge and biofilm, there is competition between sludge and membrane microorganisms, and more phosphorus and carbon sources are needed compared with after sludge discharge; after sludge discharge, activated sludge is removed, and only the microorganisms in the biofilm grow, and the demand for phosphorus and carbon is reduced. After sludge discharge, a proper amount of phosphorus is needed to maintain the abundance of phosphorus accumulating bacteria, and after regulating dissolved oxygen, HRT, carbon source, the secretion of polysaccharide bacteria AHLs and EPS increases, more AHLs are beneficial to promote the release and absorption of phosphorus by phosphorus accumulating bacteria, and the increase of EPS provides more places and active points for the release and absorption of phosphorus, which is beneficial to the improvement of the phosphorus removal and recovery capacity of the biofilm under the combined action of phosphorus accumulating bacteria cells and polysaccharide bacteria EPS, so that the phosphorus recovery is more economical and efficient.

[0050] The water component in the aerobic phase during the biofilm formation stage: 5 mg / L of KH2PO4, 300 mg / L of NaHCO3, 40 mg / L of NH4Cl, 8 mg / L of CaCl2·2H2O, 30 mg / L of MgSO4·7H2O, 2 mg / L of disodium ethylenediaminetetraacetate (EDTA·2Na), and 0.5 μM of C6-HSL. The water component in the anaerobic phase during the biofilm formation stage: 100 mg / L of sodium acetate in the first cycle and tap water, and then supplementing sodium acetate (100 mg / L) and recycling the anaerobic recovery liquid until the enrichment culture is completed.

[0051] 0.1-1.0 μM of AHLs is added during the biofilm formation stage, and no AHLs is added after sludge discharge; the effective types of AHLs added are one or more of C4-HSL, C6-HSL, C8-HSL, and 3OC10-HSL. The addition of AHLs in a short time during the biofilm formation stage is beneficial to promote the adhesion and growth of Candidatus Competibacter (a kind of polysaccharide bacteria) on the filler, and the enrichment and selection of Candidatus Competibacter is realized through the adhesion of Candidatus Competibacter. After sludge discharge, the content of Candidatus Competibacter has reached a certain amount, and the time from after sludge discharge to the completion of enrichment culture is relatively long, about 3 / 4 of the entire enrichment culture time, and it is more economical and feasible to stimulate the secretion of AHLs and EPS by Candidatus Competibacter to realize the strengthening effect of the biofilm process on the release and absorption of phosphorus.

[0052] After sludge discharge, the phosphate concentration of the aerobic influent and the carbon source concentration of the anaerobic influent are halved, and no AHLs is added, and the other components of the aerobic influent and the anaerobic influent are consistent with those in the biofilm formation stage.

[0053] 3. Enrichment culture

[0054] The biomass and the content of Candidatus Competibacter at the completion of the enrichment culture are determined to jointly indicate the change of the content of Candidatus Competibacter in the biofilm, which is more rigorous and reliable. At the same time, the low-carbon and high-efficiency phosphorus recovery capacity of the biofilm at the completion of the enrichment culture is evaluated in combination with the carbon source consumption, phosphorus removal and phosphorus recovery liquid concentration indicators, which is more comprehensive.

[0055] The time required for the phosphate concentration in the anaerobic enrichment tank b to stop rising from the start of the biofilm formation is recorded, that is, the time required for the enrichment culture of glycan bacteria. At the same time, the phosphorus content and COD consumption of the biofilm at the completion of the enrichment culture are determined to obtain the phosphorus removal efficiency and the recovery liquid concentration, and the content of Candidatus Competibacter, the biomass and the content of AHLs of the biofilm are determined. All the results at the completion of the enrichment culture are recorded in Table 1. As can be seen from Table 1, the enrichment culture time of 28 days is lower than the currently reported minimum time of 39 days, under the premise of high AHLs and EPS secretion, the content of Candidatus Competibacter at the completion of the enrichment culture is 25%, and a high phosphorus removal efficiency (99.65%) and a phosphate recovery liquid concentration (157 mg / L) are obtained, the enriched phosphate concentration is higher than 50 mg / L, which is economically feasible for the recovery of phosphorus products by the struvite method, indicating that the current method for enriching Candidatus Competibacter is economical, fast and effective.

[0056] Table 1 Enrichment culture conditions of Example 1

[0057] Example 2

[0058] 1. Process running device and running process

[0059] The same as Example 1. The difference is that the sludge is discharged when the biofilm thickness and adhesion force increase by 55% and 53% respectively compared with the previous day.

[0060] 2. Influent composition of the process

[0061] The same as Example 1, the difference is that no AHLs are added in the aerobic influent during the biofilm formation stage.

[0062] 3. Enrichment culture conditions

[0063] Consistent with example 1, the difference is that all the results recorded in table 2 when the enrichment culture is completed, and the relative abundance of phosphorus accumulating bacteria in activated sludge is 2.98%, and the relative abundance of glycan bacteria Candidatus Competibacter is 0.57%. As can be seen from table 2, the enrichment culture time is 50 days, which is higher than the minimum time of 39 days currently reported, and the AHLs and EPS content produced by the biofilm and the Candidatus Competibacter content at the end of the enrichment culture are lower than those in table 1. The phosphorus removal efficiency and phosphate recovery liquid concentration of the biofilm obtained are also lower than those in table 1. It is shown that under the process operation mode without adding C6-HLS in the biofilm formation stage, under the longer enrichment culture time, the Candidatus Competibacter content, biofilm phosphorus removal efficiency and phosphate recovery liquid concentration obtained are lower than those under the operation mode of adding C6-HLS in the biofilm formation stage of example 1. Therefore, adding C6-HLS in the biofilm formation stage is beneficial to the enrichment culture of Candidatus Competibacter, phosphorus removal and phosphorus recovery.

[0064] Table 2 enrichment culture of example 2

[0065] Example 3:

[0066] 1. Process running device and running process

[0067] Consistent with example 1. The difference is that the reactor filler filling ratio is 40%, the activated sludge (sludge concentration 10000 mg / L) of the secondary sedimentation tank of the A2O process of the sewage treatment plant is added in the biofilm formation stage, the aerobic and anaerobic stirring speed is 50 rpm in the biofilm formation stage, and the aerobic and anaerobic stirring speed is 70 rpm after sludge discharge. When the biofilm thickness and adhesion force increase by 69% and 58% respectively compared with the previous day, sludge discharge is carried out.

[0068] 2. Process influent composition

[0069] Consistent with example 1, the difference is that 1.0 μM of C4-HSL is added in the aerobic influent in the biofilm formation stage. The phosphate in the aerobic influent in the biofilm formation stage is 10 mg / L, the anaerobic carbon source is 200 mg / L, the dissolved oxygen is 6 mg / L, and the HRT is aerobic 3 h / anaerobic 2 h. After sludge discharge, the phosphate in the aerobic influent is 5 mg / L, the anaerobic carbon source is 100 mg / L, the dissolved oxygen is 8 mg / L, and the HRT is aerobic 4 h / anaerobic 2 h.

[0070] 3. Enrichment culture

[0071] Consistent with example 1, the difference is that all the results recorded in table 3 when the enrichment culture is completed, and the relative abundance of polyphosphorus bacteria in activated sludge is 3.21%, and the relative abundance of glycan bacteria Candidatus Competibacter is 1.32%. As can be seen from table 3, the enrichment culture time is 30 days, which is lower than the minimum time of 39 days currently reported, and the AHLs and EPS content produced by the biofilm and the content of Candidatus Competibacter when the enrichment culture is completed are higher than table 2, the phosphorus removal efficiency and phosphate recovery liquid concentration obtained by the biofilm are also higher than table 2, and have similar effects with table 1, but table 3 has higher water phosphorus concentration and anaerobic carbon source than table 1, so the phosphate recovery liquid concentration obtained by table 3 under more carbon source consumption, EPS content and AHLs content is 226mg / L, which is significantly higher than 157mg / L of table 1. It is shown that under the process operation mode of adding C4-HLS in the biofilm formation stage, the regulation of suitable aerobic influent phosphorus concentration, anaerobic carbon source concentration, stirring speed, aerobic HRT, dissolved oxygen and sludge discharge time (biofilm thickness and adhesion force compared with the growth rate of the previous day) will have a significant impact on the phosphate recovery liquid concentration, but has no obvious effect on the enrichment culture time and content of Candidatus Competibacter.

[0072] Table 3 enrichment culture of example 3

[0073] Effect evaluation 1:

[0074] From the above embodiments 1 to 3, it can be seen that, under the process operation conditions of activated sludge concentration not less than 8000 mg / L, phosphorus concentration of 5-10 mg / L in aerobic influent, stirring speed of 40-50 rpm, dissolved oxygen of 5-6 mg / L, HRT of 2-3 h in aerobic stage and 1-2 h in anaerobic stage, 0.1-1.0 μM of AHLs, and anaerobic carbon source concentration of 100-200 mg / L in the biofilm formation stage, and under the process operation conditions of phosphorus concentration of 2.5-5 mg / L in aerobic influent, stirring speed of 60-70 rpm, dissolved oxygen of 7-8 mg / L, HRT of 3-4 h in aerobic stage and 1-2 h in anaerobic stage, and anaerobic carbon source concentration of 50-100 mg / L after sludge discharge, it is feasible to rapidly enrich and culture Candidatus Competibacter. The sludge is discharged when the thickness and adhesion of the biofilm increase by more than 50% compared with the previous day, and under the enrichment and culture time of 28-30 days, the process effect of phosphorus removal efficiency of 99.18%-99.65% and phosphorus recovery liquid concentration of 157-226 mg / L is obtained, and the obtained phosphorus recovery liquid is suitable for recovering phosphorus products by the struvite method and has good economic value. Compared with the current research on enrichment and culture of Candidatus Competibacter, the present application adds AHLs with a suitable concentration in the biofilm formation stage and adjusts the process operation conditions after sludge discharge to promote the production of AHLs and EPS by Candidatus Competibacter, which not only achieves rapid enrichment and culture of Candidatus Competibacter but also helps low-carbon and efficient phosphorus recovery, and is a feasible and economical method for rapid enrichment and culture of Candidatus Competibacter, enhanced biofilm phosphorus removal and phosphorus recovery.

[0075] Effect evaluation 2:

[0076] Under the same process operation mode, compared with no addition of AHLs, the addition of AHLs reduces the carbon source consumption of 21 mg / L for enrichment and culture of Candidatus Competibacter, shortens the enrichment and culture time by 22 days, increases the content of enriched and cultured Candidatus Competibacter by 15%, and increases the biofilm phosphorus removal efficiency and the phosphorus recovery liquid concentration by 8.76% and 44 mg / L respectively after the enrichment and culture is completed. This way of promoting Candidatus Competibacter to secrete EPS and preferentially adhere to the filler by adding AHLs and then expanding the culture saves time and operation cost and improves the phosphorus recovery efficiency, and is a more economical and efficient method for enrichment and culture of Candidatus Competibacter which contributes to phosphorus removal and phosphorus recovery.

[0077] Effect evaluation 3:

[0078] In the case of adding AHLs in the biofilm formation stage, the process operation parameters such as sludge concentration, phosphorus concentration in the aerobic influent, carbon source dosage in the anaerobic stage, dissolved oxygen, HRT, sludge discharge timing, etc. have no significant influence on the enrichment culture time of Candidatus Competibacter and the content at the time of enrichment completion, and with the increase of influent phosphorus, appropriate increase of carbon source dosage can obtain higher phosphorus recovery liquid concentration, which shows that as long as AHLs are added in the biofilm formation stage, combined with appropriate process operation regulation strategy, Candidatus Competibacter can be rapidly, stably and efficiently enriched and cultured, and the biofilm has good phosphorus recovery capacity.

[0079] Obviously, the above embodiments are only examples for clearly illustrating, not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments cannot be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture, characterized in that, The method comprises a biofilm formation stage and a sludge discharge and post-sludge discharge stage. The biofilm formation stage comprises the following steps: S11: adding activated sludge and aerobic sewage A containing phosphates and N-acyl homoserine lactone into a main reactor containing suspended filler, and discharging liquid after 2-3 hours of aerobic treatment; the activated sludge contains phosphorus accumulating organisms and Candidatus Competibacter; S12: adding water, carbon source and anaerobic phosphorus recovery liquid in a recovery tank into the main reactor, and discharging liquid into the recovery tank after 1-2 hours of anaerobic treatment; the concentration of the carbon source in the main reactor is maintained at 100-200 mg / L during the anaerobic treatment; S13: repeating steps S11 and S12 until the thickness and adhesion of the biofilm increase by not less than 50% compared with 24 hours ago, and entering the sludge discharge and post-sludge discharge stage; the biofilm is formed by microorganisms in the activated sludge gathering on the suspended filler; The sludge discharge and post-sludge discharge stage comprises the following steps: S21: discharging activated sludge in the main reactor, adding aerobic sewage B, and discharging the sewage in the main reactor after 3-4 hours of aerobic treatment; the concentration of phosphates in the aerobic sewage B is 45-55% of that in the aerobic sewage A; S22: adding water, carbon source and anaerobic phosphorus recovery liquid in the recovery tank into the main reactor, and discharging the sewage into the recovery tank after 1-2 hours of anaerobic treatment; the concentration of the carbon source is 45-55% of that in the biofilm formation stage; S23: repeating steps S21 and S22 until the concentration of phosphates in the recovery tank remains unchanged.

2. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 1, wherein, In steps S11 and S21, the water inflow of the reactor is 750-850 mL / min, and the water inflow time is 5-10 min.

3. The method for phosphorus removal and recovery by enriching and culturing polysaccharide-rich bacteria to strengthen biofilms, as described in claim 1, is characterized in that... In step S11, the filling ratio of the suspended filler is 30-40%.

4. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide-accumulating bacteria through enrichment culture according to claim 1, wherein, In steps S11 and S21, stirring and aeration are performed during aerobic treatment.

5. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 4, wherein, In step S11, the concentration of dissolved oxygen during aerobic treatment is 5-6 mg / L; in step S21, the concentration of dissolved oxygen during aerobic treatment is 7-8 mg / L.

6. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 1, wherein, In the biofilm formation stage and the sludge discharge and post-sludge discharge stage, the pH value in the main reactor during aerobic stage and anaerobic stage is 7-7.

5.

7. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 1, wherein, The aerobic sewage A comprises 5-10 mg / L of KH2PO4, 280-320 mg / L of NaHCO3, 35-45 mg / L of NH4Cl, 6-10 mg / L of CaCl2·2H2O, 25-35 mg / L of MgSO4·7H2O, 1-3 mg / L of EDTA·2Na, and 0.1-1.0 μM of N-acyl homoserine lactone.

8. The method of removing phosphorus and recovering phosphorus by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 1, wherein, The main reactor in the biofilm formation stage is stirred at a speed of 40-50 rpm, and the main reactor in the sludge discharge and post-sludge discharge stage is stirred at a speed of 60-70 rpm.

9. The method for phosphorus removal and recovery by enhancing biofilm with polysaccharide bacteria enriched culture according to claim 1, wherein, The N-acylhomoserine lactones are selected from one or more of N-butyryl-L-homoserine lactone, N-hexanoyl-L-homoserine lactone, N-octanoyl-L-homoserine lactone, and N-3-oxo- hexanoyl-L-homoserine lactone.

10. The method for enhanced biological phosphorus removal and recovery of phosphorus by culturing Glycogen-accumulating Organisms (GAOs) in a phosphorus-limited fed-batch culture as claimed in claim 1, wherein, The carbon source is sodium acetate.

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