A method and process for enriching and culturing a polyphosphate biofilm utilizing multiple carbon sources

Abstract

The present invention provides a method and process for enriching and culturing a polyphosphate biofilm using multiple carbon sources. A biofilm with an appropriate amount of N-acyl-homoserine lactone content of ≥1500 μg / L and a biochemical oxygen demand of ≥49000 mg / L is taken and crushed to a biofilm particle size of ≤0.2 μm under low temperature conditions, and then added to sterilized ultrapure water to prepare a biofilm crushing liquid. The biofilm reactor is operated alternately aerobic / anaerobic, and the biofilm crushing liquid and a small molecule carbon source are added in each anaerobic stage until the phosphorus absorption and phosphorus release of the biofilm no longer increase, thereby obtaining an enriched and cultured polyphosphate biofilm. By adding the biofilm crushing liquid as one of the anaerobic carbon sources for enrichment and cultivation of the polyphosphate biofilm, on the one hand, anaerobic multiple carbon sources are provided for the polyphosphate bacteria of the biofilm, and on the other hand, a large amount of N-acyl-homoserine lactones secreted by the biofilm are used to promote the adhesion formation and carbon source uptake and utilization ability of the biofilm, thereby shortening the culture time and improving the abundance of polyphosphate bacteria and the phosphorus absorption and release performance.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method and process for enriching and culturing a polyphosphate biofilm utilizing multiple carbon sources. Background Art

[0002] The enrichment and cultivation of polyphosphate biofilm is the prerequisite for the use of biofilm method to remove and enrich phosphate. Among them, polyphosphate biofilm refers to a biofilm containing a large number of polyphosphate bacteria (PAOs). Based on the principle that polyphosphate bacteria aerobicly absorb phosphorus and anaerobically consume carbon sources to release phosphorus, it can achieve the simultaneous removal and enrichment of phosphate in sewage, which not only solves the pollution problem of excessive phosphorus content in water bodies but also realizes the recycling of phosphorus resources, and has good application potential. It needs to first undergo the biofilm formation of activated sludge, and then be domesticated and grown under different process operation modes and different types of anaerobic carbon sources, and finally complete the enrichment and cultivation of polyphosphate biofilm. The polyphosphate biofilm must consume carbon sources in the anaerobic stage to release phosphorus. Under the same conditions, the more phosphorus is released, the more carbon sources are consumed.

[0003] At present, the activated sludge used for biofilm cultivation to form polyphosphate biofilm comes from the enhanced biological phosphorus removal process (EBPR process for short) of actual sewage treatment plants. The EBPR process uses the carbon source in actual sewage to remove phosphate but does not perform high-multiple enrichment to recover phosphate.

[0004] Common methods for enriching and culturing polyphosphate biofilms include: 1) alternating aerobic and anaerobic operation, with aerobic operation without a carbon source and anaerobic operation supplemented with 200-2000 mg / L of chemical oxygen demand (hereinafter referred to as COD), such as adding a corresponding amount of sodium acetate to supplement COD; 2) alternating anaerobic and aerobic operation, with 1300 mg / L of COD supplemented in stages during the anaerobic period; 3) three operating modes are used during the anaerobic period, namely intermittent, continuous, and continuous cycle; 4) the carbon source is sodium acetate, sodium propionate, glucose, amino acids, etc., used alone or in combination. At present, these methods mainly have the following problems: 1) The carbon sources used for enrichment and culture of polyphosphate biofilms are mostly small molecule carbon sources (acetic acid, propionic acid, glucose, etc.). Therefore, the carbon source type used for enrichment and culture of polyphosphate biofilms is single. When facing actual sewage with multiple carbon sources, it is necessary to add additional small molecule carbon sources (dosage ≥ 200 mg / L) to ensure the efficiency of anaerobic phosphorus release, thereby increasing the operating cost of phosphorus recovery; 2) The biofilm process does not discharge sludge for a long time and the sludge age is long. The growth rate of polyphosphate biofilm is slow under long sludge age, and the time for enrichment and culture of polyphosphate biofilm is long.

[0005] In view of this, it is necessary to improve the method of enriching and culturing polyphosphate biofilm in the prior art to solve the above problems. Summary of the invention

[0006] The purpose of the present invention is to provide a method and process for enriching and culturing a polyphosphate biofilm using multiple carbon sources, so as to solve the problems in the prior art that the polyphosphate biofilm enriched and cultured uses a single carbon source and the biofilm domestication takes a long time.

[0007] To achieve the above-mentioned purpose, the present invention provides a method for enriching and culturing a polyphosphate biofilm using multiple carbon sources, wherein an appropriate amount of biofilm with a content of N-acyl-homoserine lactone ≥1500 μg / L and a biochemical oxygen demand ≥49000 mg / L is taken, crushed to a biofilm particle size of ≤0.2 μm under low temperature conditions, and then added to sterilized ultrapure water to prepare a biofilm crushing liquid, and a biofilm reactor is operated alternately aerobic / anaerobic, and the biofilm crushing liquid and a small molecule carbon source are added in each anaerobic stage until the amount of phosphorus absorbed and released by the biofilm no longer increases, thereby obtaining an enriched and cultured polyphosphate biofilm.

[0008] As a further improvement of the present invention, the 1st to 3rd day of each phosphate harvesting cycle in the stable operation stage is used as the rapid phosphorus release stage, and the biofilm in the rapid phosphorus release stage is broken under low temperature conditions to a biofilm particle size of ≤0.2 μm and then added into sterilized ultrapure water to prepare a biofilm breaking liquid.

[0009] As a further improvement of the present invention, the preparation method of the biofilm disruption liquid is: 40-50 mL of sterilized ultrapure water is added to every 10 g of biofilm as a mixing ratio, the biofilm in the rapid phosphorus release stage is mixed in the sterilized ultrapure water, and the biofilm is disrupted in an ultrasonic environment of 0°C and 350-400W for not less than 0.5h.

[0010] As a further improvement of the present invention, the small molecule carbon source is acetic acid, sodium acetate or propionic acid.

[0011] The present invention also provides a process for enriching and culturing a polyphosphate biofilm using multiple carbon sources, comprising the following steps:

[0012] 1) Biofilm culture: adding pretreated activated sludge into a biofilm reactor, operating the biofilm reactor alternately aerobically / anaerobically, and carrying out biofilm culture of polyphosphate-accumulating bacteria on the suspended filler in the biofilm reactor; wherein, in the anaerobic stage, adding a small molecule carbon source and the biofilm disruption liquid prepared as described in claim 1, and recycling the anaerobic effluent in the anaerobic stage, the sludge is discharged when the thickness of the biofilm on the suspended filler increases slowly and the amount of phosphorus absorbed and released by the biofilm is greater than that of the activated sludge;

[0013] 2) Enrichment culture stage: After sludge discharge, the biofilm reactor continues to operate alternately aerobic / anaerobic until the phosphorus absorption and release of the biofilm no longer increase, and an enriched and cultured polyphosphate biofilm is obtained.

[0014] As a further improvement of the present invention, in step 1), the preparation method of the biofilm disruption liquid is:

[0015] The 1st to 3rd day of each phosphate harvesting cycle in the stable operation stage of the process is used as the rapid phosphorus release stage. The biofilm in the rapid phosphorus release stage is broken under low temperature conditions to a biofilm particle size of ≤0.2 μm, and then added into sterilized ultrapure water to prepare a biofilm breaking liquid.

[0016] As a further improvement of the present invention, the preparation method of the biofilm disruption liquid is: 40-50 mL of sterilized ultrapure water is added to every 10 g of biofilm as a mixing ratio, the biofilm in the rapid phosphorus release stage is mixed in the sterilized ultrapure water, and the biofilm is disrupted in an ultrasonic environment of 0°C and 350-400W for not less than 0.5h.

[0017] As a further improvement of the present invention, the pretreatment of the activated sludge in step 1) includes: taking the activated sludge, adding sodium acetate, NH4Cl and KH2PO4 in a ratio of COD:N:P=100:5:1, stirring the sludge, and then subjecting the activated sludge to anaerobic exposure.

[0018] As a further improvement of the present invention, the small molecule carbon source is acetic acid, sodium acetate or propionic acid.

[0019] As a further improvement of the present invention, in step 1), the stirring speed in the biofilm reactor is 50-60 rpm; in step 2), the stirring speed in the biofilm reactor is 80-90 rpm.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention discloses a method and process for enriching and culturing a polyphosphate biofilm using multiple carbon sources. By adding biofilm disruption liquid in a rapid phosphorus-releasing stage as one of the anaerobic carbon sources for enriching and culturing the polyphosphate biofilm, on the one hand, a variety of carbon sources in the anaerobic stage are provided for the polyphosphate-accumulating bacteria in the biofilm. On the other hand, a large amount of N-acyl-homoserine lactones (AHLs) secreted by the biofilm in the rapid phosphorus-releasing stage are utilized to promote the adhesion formation and carbon source uptake and utilization ability of the biofilm, thereby shortening the culture time and improving the abundance of polyphosphate-accumulating bacteria and the phosphorus absorption and release performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic diagram of a process flow of an enrichment culture polyphosphate biofilm process utilizing multiple carbon sources provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The present invention is described in detail below in conjunction with the various embodiments shown in the accompanying drawings, but it should be noted that these embodiments are not limitations of the present invention, and any equivalent transformations or substitutions in functions, methods, or structures made by ordinary technicians in the field based on these embodiments are all within the scope of protection of the present invention.

[0024] Combination Figure 1 As shown, the present invention provides a process for enriching and culturing a polyphosphate biofilm utilizing multiple carbon sources. The devices involved in the process operation include: a biofilm reactor 1 equipped with a suspended filler 11, an aeration device 12, an agitator 13 and a data acquisition device 14 connected to the biofilm reactor 1, a wastewater storage device 2, a phosphorus recovery device 3 and a carbon source dosing device 4 connected to the biofilm reactor 1.

[0025] The process is as follows:

[0026] The activated sludge after anaerobic exposure is added into the biofilm reactor 1 , and the biofilm reactor 1 is operated alternately aerobically and anaerobically, and the biofilm of polyphosphate bacteria is cultured on the suspended filler 11 in the biofilm reactor 1 .

[0027] In the aerobic stage, phosphorus-containing wastewater flows into the biofilm reactor 1 from the wastewater storage device 2, the aeration device 12 provides an aerobic environment, and the stirrer 13 is turned on for stirring to make the water quality uniform. After the aerobic stage is over, the aeration device 12 is closed and the wastewater is discharged; switching to the anaerobic stage, the anaerobic inlet water in the phosphorus recovery device 3, the biofilm breaking liquid and sodium acetate in the carbon source addition device 4 are pumped into the biofilm reactor 1 at the same time, and the anaerobic effluent is recovered to the phosphorus recovery device 3.

[0028] Through aerobic / anaerobic alternating operation, no carbon source is added during aeration in the aerobic stage, and the polyphosphate bacteria on the biofilm absorb phosphates in the phosphorus-containing wastewater; in the anaerobic stage, only the biofilm breaking liquid and sodium acetate are stirred and added to mix with the anaerobic influent and passed into the biofilm reactor 1, and the polyphosphate bacteria use the carbon source in the biofilm breaking liquid and sodium acetate to release the accumulated phosphate in the body into the phosphorus recovery liquid; the anaerobic stage of each subsequent cycle uses the phosphorus recovery liquid as the anaerobic influent. The polyphosphate bacteria are enriched and cultured in the biofilm reactor 1, and the phosphate concentration of the phosphorus recovery liquid in the phosphorus recovery device 3 is also getting higher and higher; in the stable operation stage of the process, the time it takes for the phosphate concentration of the phosphorus recovery liquid in the phosphorus recovery device 3 to rise from 0 mg / L to the highest concentration and no longer rise is a phosphate harvesting cycle (in days).

[0029] In the following, experiments were conducted with the carbon sources added in the anaerobic stage being sodium acetate (COD 100 mg / L), 50 mL of biofilm disruption liquid, 50 mL of biofilm disruption liquid + sodium acetate (COD 100 mg / L), and 40 mL of biofilm disruption liquid + sodium acetate (COD 100 mg / L), respectively, to compare the effects of adding a mixture of biofilm disruption liquid and sodium acetate, adding only biofilm disruption liquid, and adding only sodium acetate in the anaerobic stage on the enrichment culture parameters of polyphosphate biofilm (including sludge discharge time, culture completion time, biofilm thickness at sludge discharge, biofilm thickness at culture completion, polyphosphate bacteria content at culture completion, phosphorus absorption at culture completion, and phosphorus release at culture completion).

[0030] The aerobic and anaerobic influent uses synthetic wastewater, the reactor influent flow rate is controlled at 900mL / min, and the influent time is about 10min. The DO in the aerobic stage is controlled at 4-6mg / L and pH7.0-7.5.

[0031] Aerobic water distribution components: 8-10mg / LKH2PO4, 300-400mg / LNaHCO3, 30-40mg / LNH4Cl, 7-10mg / LCaCl2·2H2O, 20-40mg / LMgSO4·7H2O, 1-2mg / LEDTA·2Na.

[0032] Anaerobic water distribution components: carbon source (40-50mL biofilm disruption solution and / or sodium acetate (COD100mg / L)), 1.4-1.5g / LNH4Cl, 0.09-0.11g / LCaCl2·2H2O, 0.5-0.7g / LMgSO4·7H2O, 0.03-0.05mg / LEDTA·2Na.

[0033] Biofilm disruption liquid: Take the 1st to 3rd day of each phosphate harvesting cycle in the stable operation stage as the rapid phosphorus release stage, take 10g of biofilm in the rapid phosphorus release stage and add 40-50mL of sterilized ultrapure water, ultrasonically disrupt it at 0℃ and 350-400W for 30min, and determine the contents of AHLs and COD before and after disruption.

[0034] Example 1

[0035] In the anaerobic stage, sodium acetate (COD 100 mg / L) was used as a carbon source to enrich and culture polyphosphate biofilm.

[0036] Experimental device combined Figure 1 As shown, it includes: a 10L biofilm reactor 1 (the filling ratio of the suspended filler 11 is 35-40%, the material is Kaldnes K1 polyethylene, the diameter is 15mm, the height is 5mm, and the average specific surface area is 900m 2 / m 3), a 180L wastewater storage device 2, a 50L phosphorus recovery device 3 and a 3L carbon source dosing device 4.

[0037] The specific steps of the process are as follows:

[0038] Step 1) Process component pretreatment

[0039] Aerobic water preparation components: 10mg / LKH2PO4, 300mg / LNaHCO3, 30mg / LNH4Cl, 7mg / LCaCl2·2H2O, 20mg / LMgSO4·7H2O, 1mg / LEDTA·2Na. The assembled aerobic water preparation is phosphorus-containing wastewater, which is pre-installed in the wastewater storage device 2.

[0040] Anaerobic water distribution components: sodium acetate (COD 100 mg / L), 1.5 g / L NH4Cl, 0.11 g / L CaCl2·2H2O, 0.5 g / LMgSO4·7H2O, 0.03 mg / LEDTA·2Na. Among them, 1.4 g / L NH4Cl, 0.09 g / L CaCl2·2H2O, 0.5 g / LMgSO4·7H2O, 0.03 mg / LEDTA·2Na water distribution components are pre-installed in the phosphorus recovery device 3 as the base liquid, and sodium acetate is pre-installed in the carbon source dosing device 4. Take 800-900 g of activated sludge in the aerobic zone of the oxidation ditch process, add 29.16 g sodium acetate, 4.35 g NH4Cl and 1 g KH2PO4 (COD: N: P = 100: 5: 1), add a small amount of water to dissolve, add to the activated sludge and stir evenly, and keep the dissolved oxygen at 8 mg / L for 2 days. The activated sludge is exposed to the atmosphere with a nutrient ratio of COD:N:P=100:5:1 for 1-2 days to allow the activated sludge to recover its activity before biofilm cultivation, which is conducive to the subsequent rapid biofilm formation success.

[0041] Step 2) Biofilm culture

[0042] The activated sludge after anaerobic exposure is added into the biofilm reactor 1 , and the biofilm reactor 1 is operated alternately for 4 hours aerobic / 2 hours anaerobic, and the biofilm of polyphosphate bacteria is cultured on the suspended filler 11 in the biofilm reactor 1 .

[0043] The water inlet flow rate of biofilm reactor 1 was set to 900 mL / min, and the water inlet time was about 10 min. The dissolved oxygen in the aerobic stage was controlled at 4 mg / L and pH 7.0.

[0044] In the aerobic stage, valve 51 is opened, and phosphorus-containing wastewater flows from wastewater storage device 2 into biofilm reactor 1 under gravity. Aeration device 12 provides an aerobic environment, and stirrer 13 (a magnetic stirrer is used in this embodiment) is turned on to stir at a low speed (60 rpm) to make the water uniform. After the actual water intake is 9L, valve 51 is closed. After the aerobic stage is carried out for 4 hours, aeration device 12 is closed and pump 55 is turned on to discharge wastewater.

[0045] In the anaerobic stage, the base liquid / phosphorus recovery liquid in the phosphorus recovery device 3 and the sodium acetate in the carbon source dosing device 4 are simultaneously pumped into the biofilm reactor 1 by pumps 52 and 54, and stirred at a low speed (60 rpm). After the anaerobic stage is carried out for 2 hours, the anaerobic effluent is returned to the phosphorus recovery device 3 by pump 53 as the anaerobic influent for the next cycle.

[0046] At the same time, the phosphorus absorption and release of the activated sludge and the biofilm on the suspended filler in the biofilm reactor 1 and the thickness of the biofilm on the suspended filler are measured every day. The phosphorus absorption and release of the activated sludge can be calculated according to formulas (a) and (b) by passing 10 mg / L of influent phosphate into the suspended filler after the suspended filler is taken out, and the phosphorus absorption and release of the biofilm can be calculated according to formulas (a) and (b) by passing 10 mg / L of influent phosphate into the taken out biofilm-containing filler.

[0047] Formula (a): Aerobic phosphorus absorption = (phosphate concentration of aerobic initial influent - phosphate concentration of aerobic final effluent) * influent volume

[0048] Formula (b): Anaerobic phosphorus release = (phosphate concentration of anaerobic final effluent - phosphate concentration of anaerobic initial influent) * influent volume

[0049] When the biofilm thickness on the suspended filler 11 increases slowly and the amount of phosphorus absorbed and released by the biofilm is greater than that of the activated sludge, the sludge can be discharged, and the sludge discharge time and biofilm thickness are recorded.

[0050] The condition for discharging activated sludge is that the thickness of the biofilm on the filler increases slowly and the amount of phosphorus absorbed and released by the biofilm is greater than that of the activated sludge. This is based on the fact that the coexistence of activated sludge and biofilm is not conducive to the growth of the biofilm and that the phosphorus absorption and release performance has been transferred from the mud to the membrane as the sludge discharge standard, which is more in line with the process goal of biofilm culture and provides a better theoretical basis for sludge discharge.

[0051] Step 3) Acclimation and cultivation of polyphosphate biofilm

[0052] After sludge discharge, the biofilm reactor 1 was continued to be operated alternately aerobically / anaerobicly, and other conditions remained unchanged. The stirring speed of the agitator 13 was adjusted to 90 rpm, and the phosphorus absorption and release of the biofilm were detected every day. When the phosphorus absorption and release of the biofilm no longer increased, it indicated that the enrichment culture of the polyphosphate biofilm was completed. The content of polyphosphate bacteria and the thickness of the biofilm were detected, and the enrichment culture time was recorded to obtain the following Table 1.

[0053] Table 1 Parameters of enrichment culture of polyphosphate biofilm

[0054]

[0055] Table 1 shows the enrichment culture parameters of polyphosphate biofilm using sodium acetate (COD 100 mg / L) as carbon source. The biofilm was cultured for 12 days before sludge discharge, and the biofilm culture was completed for 35 days. The thickness of the biofilm was 35±5 μm when the sludge was discharged, and the thickness of the biofilm was 183±5 μm when the culture was completed, indicating that the biofilm grew rapidly after sludge discharge, reaching a higher PAOs abundance (30.25%), and had good phosphorus absorption and release performance (phosphorus absorption 7.2 mg and phosphorus release 5.76 mg).

[0056] Example 2

[0057] The same process flow as in Example 1 was used, and 50 mL of biofilm disruption liquid was used as a carbon source to enrich and culture polyphosphate biofilm in the anaerobic stage for the experiment.

[0058] In step 1), the process parameters for pretreatment of the process components are adjusted as follows:

[0059] Aerobic water distribution components: 10mg / LKH2PO4, 400mg / LNaHCO3, 40mg / LNH4Cl, 10mg / LCaCl2·2H2O, 40mg / LMgSO4·7H2O, 2mg / LEDTA·2Na.

[0060] Preparation of biofilm disruption liquid: 10 g of biofilm in the rapid phosphorus release stage (the 1st to 3rd day of each phosphate harvesting cycle in the stable operation stage of the process is the rapid phosphorus release stage) was added with 50 mL of sterilized ultrapure water, and ultrasonically disrupted at 0°C and 350-400W for 30 minutes to prepare a biofilm disruption liquid. The contents of N-acyl-homoserine lactone (AHLs) and biochemical oxygen demand (COD) before and after disruption were determined, and the results are shown in Table 2 below.

[0061] Table 2 AHLs and COD contents before and after biofilm disruption during rapid phosphorus release

[0062]

[0063] The biofilm rupture liquid in the rapid phosphorus release stage contains a large amount of protein, lipids, sugars and corresponding hydrolases. As can be seen from Table 2, the AHLs and COD before and after the biofilm rupture basically did not change. The rupture process under low temperature conditions retained the enzyme activity. These enzymes can hydrolyze the macromolecular carbon source into a small molecular carbon source that is easy to use by PAOs, supplement a variety of available carbon sources, and provide environmental conditions for the domestication and screening of PAOs that can use a variety of carbon sources. The role of rupture is to break the bacteria, and the proteins, polysaccharides, lipids and corresponding hydrolases inside are released. Then the cell membrane is homogenized by ultrasound, and the macromolecular carbon source is partially hydrolyzed by the hydrolase into small molecules, and finally the carbon source in the biofilm is evenly dispersed in the anaerobic influent in the form of small particles or small molecules, which is conducive to the uptake and utilization of polyphosphate bacteria.

[0064] Anaerobic water preparation components: 50mL biofilm disruption liquid, 1.5g / LNH4Cl, 0.11g / LCaCl2·2H2O, 0.7g / LMgSO4·7H2O, 0.05mg / LEDTA·2Na.

[0065] Take 800-900g of activated sludge from the aerobic zone of the oxidation ditch process, add 29.16g of sodium acetate, 4.35g of NH4Cl and 1g of KH2PO4 (COD:N:P=100:5:1), dissolve in a small amount of water, add to the activated sludge and stir evenly, and keep the dissolved oxygen at 7mg / L for continuous exposure for 1 day.

[0066] In step 2), the process parameters of biofilm culture are adjusted as follows:

[0067] The dissolved oxygen in the aerobic stage of the biofilm reactor 1 was controlled at 6 mg / L and pH 7.5.

[0068] When the biofilm reactor 1 was operated alternately for 4 hours aerobic / 2 hours anaerobic, stirring was performed at a low speed (50 rpm). The carbon source added in the anaerobic stage was only the biofilm breaking liquid.

[0069] In the acclimatization and cultivation stage of the polyphosphate biofilm in step 3), the phosphorus uptake and release of the biofilm were detected every day. When the phosphorus uptake and release of the biofilm no longer increased, it indicated that the enrichment cultivation of the polyphosphate biofilm was completed. The content of polyphosphate bacteria and the thickness of the biofilm were detected, and the enrichment cultivation time was recorded to obtain the following Table 3.

[0070] Table 3 Parameters of polyphosphate biofilm enrichment culture

[0071]

[0072] Table 3 shows the parameters of enrichment culture of polyphosphate biofilm using 50mL biofilm disruption liquid in the rapid phosphorus release stage as carbon source; compared with Table 1, it is found that 50mL biofilm disruption liquid as carbon source shortens the sludge discharge time by 2 days compared with sodium acetate (COD 100mg / L) as carbon source, and the biofilm thickness during sludge discharge and the biofilm thickness after culture completion increase significantly (P value of significant difference analysis <0.05), while the culture completion time, polyphosphate bacteria content and phosphorus absorption and release performance do not change significantly (P value of significant difference analysis >0.05). This shows that 50mL biofilm disruption liquid in the rapid phosphorus release stage as carbon source promotes the adhesion growth of biofilm compared with pure sodium acetate (COD 100mg / L), but the carbon source uptake and utilization capacity evaluated based on anaerobic phosphorus release is not significantly improved (P value of significant difference analysis >0.05), which also shows that the effect of 50mL biofilm disruption liquid in the rapid phosphorus release stage and sodium acetate (COD 100mg / L) in enrichment culture of polyphosphate biofilm is equivalent.

[0073] Example 3

[0074] The same process flow as in Example 1 was used, and in the anaerobic stage, 50 mL of biofilm disruption liquid and sodium acetate (COD 100 mg / L) were used as carbon sources to enrich and culture polyphosphate biofilm for experiments.

[0075] In step 1), the process parameters for pretreatment of the process components are adjusted as follows:

[0076] Aerobic water distribution components: 8mg / LKH2PO4, 300mg / LNaHCO3, 30mg / LNH4Cl, 7mg / LCaCl2·2H2O, 20mg / LMgSO4·7H2O, 1mg / LEDTA·2Na.

[0077] Biofilm disruption liquid: Take 10g of biofilm in the rapid phosphorus release stage and add 50mL of sterilized ultrapure water. Ultrasonic disruption is performed at 0℃ and 400W for 30min. The contents of AHLs and COD before and after disruption are determined. The results are shown in Table 4 below.

[0078] Table 4 AHLs and COD contents before and after biofilm disruption during rapid phosphorus release

[0079]

[0080] As can be seen from Table 4, there is basically no change in AHLs and COD before and after biofilm disruption. The disruption process under low temperature conditions retains enzyme activity. These enzymes can hydrolyze macromolecular carbon sources into small molecular carbon sources that are easy for PAOs to utilize, supplementing a variety of available carbon sources and providing environmental conditions for the domestication and screening of PAOs that can utilize a variety of carbon sources. Anaerobic water distribution components: 50mL biofilm disruption liquid (COD 2537.5-2540mg / L) and 128.21mg of sodium acetate (COD 100mg / L), 1.4g / LNH4Cl, 0.09g / LCaCl2·2H2O, 0.5g / LMgSO4·7H2O, 0.03mg / LEDTA·2Na.

[0081] Sodium acetate is one of the best carbon sources for PAOs to form advantages and complete phosphorus absorption and release performance. Supplementing some sodium acetate while adding biofilm disruption liquid in the rapid phosphorus release stage can, on the one hand, provide PAOs with a directly available carbon source, which is beneficial to maintain the metabolic activity of PAOs and thus shorten the culture time of the biofilm; on the other hand, it is beneficial to retain those PAOs that can only use small molecular volatile fatty acids (such as acetic acid) as carbon sources.

[0082] Take 900g of activated sludge from the aerobic zone of the oxidation ditch process, add 29.16g of sodium acetate, 4.35g of NH4Cl and 1g of KH2PO4 (COD:N:P=100:5:1), dissolve in a small amount of water, add to the activated sludge and stir evenly, and keep the dissolved oxygen at 7mg / L for 2 days.

[0083] In step 2), the process parameters of biofilm culture are adjusted as follows:

[0084] The dissolved oxygen in the aerobic stage of the biofilm reactor 1 was controlled at 4 mg / L and pH 7.0.

[0085] When the biofilm reactor 1 was operated alternately for 4 hours aerobic / 2 hours anaerobic, stirring was performed at a low speed (60 rpm). In the anaerobic stage, 50 mL of biofilm disruption liquid + sodium acetate (COD 100 mg / L) was added.

[0086] During the acclimation and cultivation stage of the polyphosphate biofilm in step 3), the phosphorus uptake and release of the biofilm were detected every day. When the phosphorus uptake and release of the biofilm no longer increased, it indicated that the enrichment cultivation of the polyphosphate biofilm was completed. The content of polyphosphate bacteria and the thickness of the biofilm were detected, and the enrichment cultivation time was recorded to obtain the following Table 5.

[0087] Table 5 Parameters of polyphosphate biofilm enrichment culture

[0088]

[0089] Table 5 shows the parameters of polyphosphate biofilm enrichment culture using 50mL of biofilm disruption liquid in the rapid phosphorus release stage and sodium acetate (COD100mg / L) as carbon sources; compared with Tables 1 and 3, it was found that 50mL of biofilm disruption liquid and sodium acetate (COD100mg / L) were used as carbon sources together, and the sludge discharge time and culture completion time were significantly shortened (sludge discharge time was shortened by 3-5d, and culture completion time was shortened by 9-10d), and the biofilm thickness at sludge discharge, biofilm thickness after culture, polyphosphate bacteria content and The phosphorus absorption and release performance increased significantly (P value of significant difference analysis < 0.05), indicating that 50mL of rapid phosphorus release stage biofilm disruption liquid and sodium acetate (COD100mg / L) as carbon sources not only promoted the adhesion and growth of biofilm PAOs, but also improved the carbon source uptake and utilization capacity evaluated based on anaerobic phosphorus release, compared with using 50mL of biofilm disruption liquid or sodium acetate (COD100mg / L) alone; this also shows that the polyphosphate bacteria on the biofilm utilized part of the carbon source in the biofilm disruption liquid for anaerobic phosphorus release, and the polyphosphate bacteria enriched and cultured in this way have the ability to utilize multiple carbon sources.

[0090] Example 4

[0091] The same process flow as in Example 1 was used, and in the anaerobic stage, 40 mL of biofilm disruption liquid and sodium acetate (COD 100 mg / L) were used as carbon sources to enrich and culture polyphosphate biofilm for experiments.

[0092] In step 1), the process parameters for pretreatment of the process components are adjusted as follows:

[0093] Aerobic water distribution components: 10mg / LKH2PO4, 400mg / LNaHCO3, 40mg / LNH4Cl, 10mg / LCaCl2·2H2O, 40mg / LMgSO4·7H2O, 2mg / LEDTA·2Na.

[0094] Biofilm disruption liquid: Take 10g of biofilm in the rapid phosphorus release stage and add 50mL of sterilized ultrapure water. Ultrasonic disruption is performed at 0℃ and 400W for 30min. The contents of AHLs and COD before and after disruption are determined. The results are shown in Table 6 below.

[0095] Table 6 AHLs and COD contents before and after biofilm disruption during rapid phosphorus release

[0096]

[0097] It can be seen from Table 6 that there was basically no change in AHLs and COD before and after biofilm disruption.

[0098] Anaerobic water distribution components: 40mL biofilm disruption liquid and sodium acetate (COD100mg / L), 1.5g / LNH4Cl, 0.11g / LCaCl2·2H2O, 0.7g / LMgSO4·7H2O, 0.05mg / LEDTA·2Na.

[0099] Take 800-900g of activated sludge from the aerobic zone of the oxidation ditch process, add 29.16g of sodium acetate, 4.35g of NH4Cl and 1g of KH2PO4 (COD:N:P=100:5:1), dissolve in a small amount of water, add to the activated sludge and stir evenly, and keep the dissolved oxygen at 7mg / L for 2 days.

[0100] In step 2), the process parameters of biofilm culture are adjusted as follows:

[0101] The dissolved oxygen in the aerobic stage of the biofilm reactor 1 was controlled at 6 mg / L and pH 7.3.

[0102] When the biofilm reactor 1 was operated alternately for 4 h aerobic / 2 h anaerobic, stirring was performed at a low speed (50 rpm). In the anaerobic stage, 40 mL of biofilm disruption liquid + sodium acetate (COD 100 mg / L) was added.

[0103] In step 3), after sludge discharge, the reactor is continued to be operated alternately aerobic / anaerobic, other conditions remain unchanged, the stirring speed is adjusted to 80 rpm, the phosphorus absorption and release of the biofilm are detected every day, and when the phosphorus absorption and release of the biofilm no longer increase, it indicates that the enrichment culture of the polyphosphate biofilm is completed, the content of polyphosphate bacteria and the thickness of the biofilm are detected, and the enrichment culture time is recorded to obtain the following Table 7.

[0104] Table 7 Parameters of polyphosphate biofilm enrichment culture

[0105]

[0106] Table 7 shows the polyphosphate biofilm enrichment culture parameters using 40mL of biofilm disruption liquid in the rapid phosphorus release stage and sodium acetate (COD100mg / L) as carbon sources; compared with Tables 1 and 3, it was found that 40mL of biofilm disruption liquid and sodium acetate (COD100mg / L) were used as carbon sources, and the sludge discharge time and culture completion time were significantly shortened compared with using 50mL of biofilm disruption liquid or sodium acetate (COD100mg / L) alone. The biofilm thickness during sludge discharge, the biofilm thickness after culture, the polyphosphate bacteria content and the phosphorus absorption and release performance were significantly increased (the significant difference analysis P value was <0.05), indicating that 40mL of biofilm disruption liquid in the rapid phosphorus release stage and sodium acetate (COD100mg / L) were used as carbon sources. Compared with using 50mL of biofilm disruption liquid or sodium acetate (COD100mg / L) alone, 100 mg / L), it not only promoted the adhesion and growth of biofilm PAOs, but also improved the carbon source uptake and utilization capacity evaluated based on anaerobic phosphorus release; this also shows that biofilm PAOs utilized part of the carbon source in the biofilm disruption liquid for anaerobic phosphorus release, and the PAOs enriched and cultured in this way have the ability to utilize multiple carbon sources.

[0107] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of the present invention. They are not intended to limit the scope of protection of the present invention. Any equivalent implementation methods or changes that do not deviate from the technical spirit of the present invention should be included in the scope of protection of the present invention.

[0108] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0109] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for enriching and culturing a polyphosphate biofilm using multiple carbon sources, characterized in that: The first to third days of each phosphate harvesting cycle in the stable operation stage are taken as the rapid phosphorus release stage, and an appropriate amount of biofilm with an N-acyl-homoserine lactone content of ≥1500 μg / L and a biochemical oxygen demand of ≥49000 mg / L in the rapid phosphorus release stage is taken and crushed to a biofilm particle size of ≤0.2 μm under low temperature conditions, and then added into sterilized ultrapure water to prepare a biofilm crushing liquid, and the biofilm reactor is operated alternately aerobically / anaerobically, and the biofilm crushing liquid and a small molecule carbon source are added in each anaerobic stage until the phosphorus absorption and release of the biofilm no longer increase, so as to obtain an enriched and cultured polyphosphate biofilm.

2. The method for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 1, characterized in that: The preparation method of the biofilm disruption liquid is as follows: 40-50 mL of sterilized ultrapure water is added to every 10 g of biofilm as a mixing ratio, the biofilm in the rapid phosphorus release stage is mixed in the sterilized ultrapure water, and the biofilm is disrupted in an ultrasonic environment at 0° C. and 350-400 W for not less than 0.5 h.

3. The method for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 1, characterized in that: The small molecule carbon source is acetic acid, sodium acetate or propionic acid.

4. A process for enriching and culturing a polyphosphate biofilm using multiple carbon sources, characterized in that: The following steps are involved: 1) Biofilm culture: adding pretreated activated sludge into a biofilm reactor, operating the biofilm reactor alternately aerobically / anaerobically, and carrying out biofilm culture of polyphosphate-accumulating bacteria on the suspended filler in the biofilm reactor; wherein, in the anaerobic stage, adding a small molecule carbon source and the biofilm disruption liquid prepared as described in claim 1, and recycling the anaerobic effluent in the anaerobic stage, the sludge is discharged when the thickness of the biofilm on the suspended filler increases slowly and the amount of phosphorus absorbed and released by the biofilm is greater than that of the activated sludge; 2) Enrichment culture stage: After sludge discharge, the biofilm reactor continues to operate alternately aerobic / anaerobic until the phosphorus absorption and release of the biofilm no longer increase, and an enriched and cultured polyphosphate biofilm is obtained.

5. The process for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 4, characterized in that: In step 1), the preparation method of the biofilm disruption liquid is: The 1st to 3rd day of each phosphate harvesting cycle in the stable operation stage of the process is used as the rapid phosphorus release stage. The biofilm in the rapid phosphorus release stage is broken under low temperature conditions to a biofilm particle size of ≤0.2 μm, and then added into sterilized ultrapure water to prepare a biofilm breaking liquid.

6. The process for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 5, characterized in that: The preparation method of the biofilm disruption liquid is as follows: 40-50 mL of sterilized ultrapure water is added to every 10 g of biofilm as a mixing ratio, the biofilm in the rapid phosphorus release stage is mixed in the sterilized ultrapure water, and the biofilm is disrupted in an ultrasonic environment at 0° C. and 350-400 W for not less than 0.5 h.

7. The process for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 4, characterized in that: The pretreatment of the activated sludge in step 1) includes: taking the activated sludge, adding sodium acetate, NH4Cl and KH2PO4 in a ratio of COD:N:P=100:5:1, stirring the activated sludge, and then subjecting the activated sludge to anaerobic exposure.

8. The process for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 4, characterized in that: The small molecule carbon source is acetic acid, sodium acetate or propionic acid.

9. The process for enriching and culturing a polyphosphate biofilm using multiple carbon sources according to claim 4, characterized in that: In step 1), the stirring speed in the biofilm reactor is 50-60 rpm; in step 2), the stirring speed in the biofilm reactor is 80-90 rpm.

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