Combined pretreatment of sludge for enhanced acid production

Abstract

The application provides a combined pretreatment sludge acid production enhancement method, and relates to the technical field of resource recycling, which comprises the following steps: placing sludge generated in a secondary sedimentation tank of a sewage treatment plant at a first set temperature for a first set time to obtain a sedimentation liquid, removing supernatant from the sedimentation liquid, and preparing the remaining objects in the sedimentation liquid into a sludge sample with a set total solid concentration; adding steel slag and PMS to the sludge sample, and carrying out anaerobic fermentation at a second set temperature for a second set time to obtain a fermentation liquid; the addition amount of the steel slag is 0.3-0.5 g / g TS, the addition amount of the PMS is 0.02-0.14 g / g TS, and the fermentation liquid is centrifuged to obtain a centrifugal liquid; the centrifugal liquid is rich in volatile fatty acids. The application can significantly improve the sludge acid production amount and realize resource utilization of the residual sludge.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, in particular to a combined pretreatment sludge acid production method. BACKGROUND

[0002] Excess sludge is a byproduct of sewage treatment plants purifying sewage, usually containing a large amount of organic matter, heavy metals and pathogens, and its treatment cost can account for 20%-60% of the operating cost of sewage treatment plants. At present, landfill, combustion and farm composting are usually used to treat excess sludge.

[0003] Anaerobic fermentation can convert organic matter into volatile fatty acids (VFAs), methane and hydrogen, and the VFAs produced can be used as a carbon source for biological denitrification and phosphorus removal in sewage treatment plants, and also as a carbon source for the synthesis of polyhydroxyalkanoate (PHA) by biological method.

[0004] The acid production of excess sludge anaerobic fermentation is low, and pretreatment methods such as alkali, heat, potassium persulfate hydrogen peroxide composite salt (PMS), calcium peroxide, etc. are usually used to strengthen the acid production process of excess sludge anaerobic fermentation. Alkali pretreatment generally uses sodium hydroxide to control pH at 9-10, which is complicated to operate and needs to adjust pH frequently, and the acid production of sludge is low. The cost of heat pretreatment method is high. SUMMARY

[0005] The purpose of the present application is to provide a combined pretreatment sludge acid production method, which is simple to operate and can significantly improve the acid production of sludge, realizing the resource utilization of excess sludge.

[0006] A combined pretreatment sludge acid production method, comprising:

[0007] S1, the sludge produced in the secondary sedimentation tank of the sewage treatment plant is placed and settled at a first set temperature for a first set time to obtain a settling liquid;

[0008] S2, removing the supernatant in the settling liquid, and preparing the remaining objects in the settling liquid into a sludge sample with a set total solid concentration; the ratio of volatile solid concentration to total solid concentration of the sludge sample is greater than a set ratio; the set ratio is 0.5;

[0009] S3, adding steel slag and PMS to the sludge sample, and anaerobically fermenting at a second set temperature for a second set time to obtain a fermentation liquid; the addition amount of the steel slag is 0.3-0.5 g / gTS, and the addition amount of the PMS is 0.02-0.14 g / gTS;

[0010] S4, centrifuging the fermentation liquor to obtain a centrifugal liquid; the supernatant of the centrifugal liquid is rich in volatile fatty acids.

[0011] Optionally, the total solid concentration is set to 12-15 g / L.

[0012] Optionally, the second set time is 9-12 days.

[0013] Optionally, the first set temperature is 4℃.

[0014] Optionally, the first set time is greater than or equal to 24 h.

[0015] Optionally, the second set temperature is 29-31℃.

[0016] Optionally, the volatile fatty acids include acetic acid, propionic acid, isobutyric acid, butyric acid, isoamyl acid and valeric acid.

[0017] The proportion of acetic acid is 46.28-50.37%, the proportion of propionic acid is 11.89-14.52%, the proportion of isobutyric acid is 5.07-8.05%, the proportion of butyric acid is 3.43-15.95%, the proportion of isoamyl acid is 11.00-15.51%, and the proportion of valeric acid is 1.71-4.74%.

[0018] The effects of the present application are as follows:

[0019] The combined pretreatment sludge and acid production method of the present application does not need to add acid and base to adjust the pH value, thereby reducing the sludge treatment cost.

[0020] The combined pretreatment sludge and acid production method of the present application significantly improves the sludge acid production.

[0021] The combined pretreatment sludge and acid production method of the present application is simple to operate, can reduce the sludge treatment cost, and realizes the reduction and resource utilization of sludge.

[0022] The combined pretreatment sludge and acid production method of the present application has a phosphorus concentration close to zero in the fermentation liquor, does not need a phosphorus removal step, and can be directly used as a carbon source for biological denitrification and phosphorus removal or a carbon source for biological synthesis of polyhydroxyalkanoate. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the flow chart of the combined pretreatment sludge and acid production method of the present application. DETAILED DESCRIPTION

[0024] Hereinafter, the embodiments of the present application will be described with reference to the accompanying drawings.

[0025] Example 1

[0026] Figure 1is a flow chart of a combined pretreatment sludge enhanced acid production method according to an embodiment of the present application. As shown in Figure 1 The present application provides a combined pretreatment sludge enhanced acid production method, which comprises:

[0027] S1, the sludge generated in the secondary sedimentation tank of the wastewater treatment plant is allowed to stand and settle at a first set temperature for a first set time to obtain a settled liquid. The first set temperature is 4°C. The first set time is greater than or equal to 24h.

[0028] S2, the supernatant in the settled liquid is removed, and the remaining objects in the settled liquid are prepared into a sludge sample with a set total solid concentration. The ratio of the volatile solid concentration to the total solid concentration of the sludge sample is greater than a set ratio; the set ratio is 0.5. The set total solid concentration is 12-15g / L.

[0029] S3, steel slag and PMS are added to the sludge sample, and anaerobic fermentation is carried out at a second set temperature for a second set time to obtain a fermentation liquid. The addition amount of steel slag is 0.3-0.5g / gTS. The addition amount of PMS is 0.02-0.14g / gTS. The second set time is 9-12 days. After the steel slag and PMS are added to the sludge sample, it is purged with nitrogen for 5min, sealed with a rubber plug to maintain an anaerobic environment, and placed in a constant temperature air shaker at 30°C and 200rpm for anaerobic fermentation for 9-12 days to obtain a fermentation liquid, so as to maximize the accumulation of volatile fatty acids (VFAs). The second set temperature is 29-31°C.

[0030] S4, the fermentation liquid is centrifuged to obtain a centrifugal liquid. The supernatant of the centrifugal liquid is rich in volatile fatty acids. The centrifugal speed is 6000r / min, and the centrifugal time is 15min. The volatile fatty acids include acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid and valeric acid.

[0031] The proportion of acetic acid is 46.28-50.37%, the proportion of propionic acid is 11.89-14.52%, the proportion of isobutyric acid is 5.07-8.05%, the proportion of butyric acid is 3.43-15.95%, the proportion of isovaleric acid is 11.00-15.51%, and the proportion of valeric acid is 1.71-4.74%.

[0032] After the supernatant of the centrifugal liquid rich in volatile fatty acids is prepared, a PHA-producing bacteria mixed liquor is prepared based on an aerobic dynamic feeding (ADF) process.

[0033] Inoculation sludge is produced from the secondary sedimentation tank of a sewage treatment plant, and the inoculation sludge concentration is 3600-5000 mg / L; artificial water is used, and acetic acid, propionic acid, butyric acid, and valeric acid are used as carbon sources, ammonium chloride is used as a nitrogen source, and potassium dihydrogen phosphate is used as a phosphorus source. The concentrations of acetic acid, propionic acid, isobutyric acid, butyric acid, isovaleric acid, and valeric acid are all converted into chemical oxygen demand (COD) concentration (mgCOD / L) for expression. The conversion coefficient of acetic acid is 1.07 gCOD / g, the conversion coefficient of propionic acid is 1.51 gCOD / g, the conversion coefficient of butyric acid and isobutyric acid is 1.82 gCOD / g, and the conversion coefficient of valeric acid and isovaleric acid is 2.04 gCOD / g. The proportions of acetic acid, propionic acid, butyric acid, and valeric acid are determined according to the VFAs composition of the fermentation broth when S3 produces volatile fatty acids optimally, the proportion of acetic acid is 46.28%-50.37%, the proportion of propionic acid is 11.89-14.52%, the proportion of butyric acid is 8.50-23.46%, and the proportion of valeric acid is 15.74-18.01%. The mass ratio of C:N:P is controlled to be 100:6-5:1; the chemical oxygen demand of the influent is 1000-1200 mg / L, the influent pH is adjusted to 7-8 by using 2M sodium hydroxide, trace element nutrient solution is added at 0.5 mL / L, and thiourea is added at 40 mg / L to inhibit nitrification.

[0034] The operation cycle (12h) of the ADF process: the influent stage (15min), the aeration stage (9h), the sedimentation stage (1.5h), the effluent stage (15min), and the standby stage (1h). At the end of the aeration stage, sludge is discharged. The aeration stage adopts mechanical stirring and air stirring simultaneously, the air stirring air volume is 70-90 L / h, the dissolved oxygen data is monitored online by a paperless recorder, and the mechanical stirring speed is 100-120 r / min; after the supernatant is discharged in the effluent stage, an equal volume of artificial water is supplemented in the influent stage, and the influent and effluent are controlled by a timer and a peristaltic pump, and the operation is cyclic; the hydraulic retention time is 1d, and the sludge retention time is 10d.

[0035] The ADF process is used for bacterial community acclimation and enrichment at 20℃-22℃.

[0036] The initial sludge containing polyhydroxyalkanoate is prepared based on the supernatant of the centrifugal liquid of the PHA-producing bacterial mixture and the centrifugal liquid.

[0037] The polyhydroxyalkanoate crystal is obtained by extracting the polyhydroxyalkanoate in the initial sludge based on the chloroform-methanol precipitation method.

[0038] Specifically, the present application includes directly preparing the initial sludge with the supernatant of the centrifugal liquid and preparing the initial sludge after denitrification treatment of the supernatant of the centrifugal liquid.

[0039] The polyhydroxyalkanoate is directly prepared with the supernatant of the centrifugal liquid as follows:

[0040] The PHA-producing bacteria mixture is aerated for a third set time, and then the supernatant of the centrifugal liquid is added, and aerobic aeration and magnetic stirring are performed for a fourth set time to obtain the initial sludge containing polyhydroxyalkanoates. The volume ratio of the PHA-producing bacteria mixture to the supernatant of the centrifugal liquid is 1:2-2.5. The third set time is 50-70 min, and the fourth set time is 12 h. After adding the supernatant of the centrifugal liquid, aerobic aeration and magnetic stirring are performed simultaneously, the aeration amount is 1.4-1.6 L / min, and the magnetic stirring speed is 280-300 r / min.

[0041] The supernatant of the centrifugal liquid is subjected to denitrification treatment to prepare polyhydroxyalkanoates:

[0042] The supernatant of the centrifugal liquid is adjusted to a set pH value, and magnetic stirring is performed at a third set temperature for a fifth set time to remove ammonia nitrogen, thereby obtaining a denitrified liquid. The pH value of the denitrified liquid is adjusted to 8 for use as a carbon source.

[0043] The PHA-producing bacteria mixture is aerated for a sixth set time, and then the denitrified liquid with a pH value of 8 is added in batches, and aerobic aeration and magnetic stirring are performed simultaneously to obtain the initial sludge containing polyhydroxyalkanoates. The sixth set time is 50-70 min.

[0044] The aerobic aeration and magnetic stirring are performed simultaneously for 1.5 h, and then the aeration and magnetic stirring are stopped, and the supernatant is removed, and then the next batch is entered, and the cycle is repeated for 5 batches.

[0045] The set pH value is 10, the fifth set time is 2.5-4 h, and the third set temperature is 60-70°C. The volume ratio of the denitrified liquid added in each batch to the PHA-producing bacteria mixture is 1:1, and the suspended solid concentration of the bacterial liquid after mixing of the denitrified liquid and the PHA-producing bacteria mixture is 2-3 g / L.

[0046] Example Two

[0047] The sludge generated in the secondary sedimentation tank of the sewage treatment plant is allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant of the settled liquid is removed, and the remaining material in the settled liquid is prepared into a 15 g / L sludge sample. 450 ml of the sludge sample is added to a serum bottle for fermentation, 0.3 g / gTS of steel slag is added, and the mixture is shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 12 days to obtain a fermentation liquid. The fermentation liquid is centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0048] The acid production amount of the sludge treated by steel slag is 276.9 mgCOD / gVS, and the volatile solid (VS) removal rate is 36.7%.

[0049] The sludge from the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid, and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the influent pH was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0050] The operation cycle (12 h) of the ADF process was as follows: an influent stage (15 min), an aeration stage (9 h), a sedimentation stage (1.5 h), a drainage stage (15 min), and a standby stage (1 h). Sludge was discharged at the end of the aeration stage. Mechanical stirring and air stirring were simultaneously performed during the aeration stage, the air stirring air volume was 70-90 L / h, the dissolved oxygen data were monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min. After the supernatant was discharged during the drainage stage, an equal volume of artificial water was added during the influent stage, and the influent and drainage were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was measured every 15 days.

[0051] The ADF process was used to acclimate and enrich the bacterial community at 20°C.

[0052] The 125 mL PHA-producing bacterial mixture was used as the seed sludge, and the seed sludge was pre-aerated for 1 h, and 310 mL of supernatant of the centrifugate was added. The aeration time was 12 h, and the aeration was started after the addition of the supernatant of the centrifugate, the aeration volume was 1.6 L / min, and the magnetic stirring speed was 300 r / min.

[0053] The PHA content in the sludge reached a maximum at 1.16 h of the synthesis reaction, and the maximum amount was 36.6 wt%, of which PHB accounted for 72% of the PHA, and PHV accounted for 28% of the PHA.

[0054] Example Three

[0055] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant of the settled liquid was removed, and the remaining substance in the settled liquid was prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.11 g / gTS of PMS was added, and the serum bottle was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0056] The acid production of the sludge treated by PMS was 134.4 mgCOD / gVS, and the VS removal rate was 38.9%.

[0057] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1; the chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 by 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0058] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air quantity was 70-90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min; after the supernatant was discharged in the effluent stage, an equal volume of artificial water was supplemented in the influent stage, the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic; the hydraulic retention time was 1 d, and the sludge retention time was 10 d; the acclimation and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0059] The ADF process was used for bacterial community acclimation and enrichment at 20°C.

[0060] 125 mL of the PHA-producing bacterial mixture was used as the seed sludge, the seed sludge was pre-aerated for 1 h, and 310 mL of the supernatant of the centrifugal liquid was added. The aeration time was 12 h, the aeration stirring was started after the addition of the supernatant of the centrifugal liquid, the aeration amount was 1.4 L / min, and the magnetic stirring speed was 300 r / min.

[0061] Example Four

[0062] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant was removed from the settled liquid, and the remaining contents of the settled liquid were prepared into a sludge sample at 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.02 g / gTS of PMS were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0063] The acid production of the sludge treated by steel slag and PMS was 287.0 mgCOD / gVS, and the VS removal rate was 40.7%.

[0064] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid, and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled at 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0065] The operation cycle of the ADF process (12 h) was as follows: influent stage (15 min), aeration stage (9 h), settling stage (1.5 h), effluent stage (15 min), and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were performed simultaneously during the aeration stage, the air stirring air volume was 70-90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min. After the supernatant was discharged during the effluent stage, an equal volume of artificial water was added during the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was measured every 15 days.

[0066] The ADF process was used for bacterial community acclimation and enrichment at 20°C.

[0067] 125 mL of the PHA-producing bacterial mixture was used as the seed sludge, the seed sludge was pre-aerated for 1 h, and 310 mL of the supernatant of the centrifugal liquid was added. The aeration time was 12 h, the aeration stirring was started after the addition of the supernatant of the centrifugal liquid, the aeration volume was 1.6 L / min, and the stirring speed was 300 r / min.

[0068] Example Five

[0069] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was allowed to settle at 4°C for 24 h to obtain a sedimentation liquid, the supernatant of the sedimentation liquid was removed, and the remaining substance in the sedimentation liquid was prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.05 g / gTS of PMS were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0070] The acid production of the sludge treated by steel slag combined with PMS was 288.5 mgCOD / gVS, and the VS removal rate was 41.4%.

[0071] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used. Acetic acid, propionic acid, butyric acid and valeric acid were used as carbon sources, ammonium chloride was used as a nitrogen source, and potassium dihydrogen phosphate was used as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 mL / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0072] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air quantity was 70-90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min. After the supernatant was discharged in the effluent stage, an equal volume of artificial water was added in the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0073] The ADF process was used for bacterial community acclimation and enrichment at 20°C.

[0074] 125 mL of the PHA-producing bacterial mixture was used as the seed sludge, the seed sludge was pre-aerated for 1 h, and 310 mL of the supernatant of the centrifugal liquid was added. The aeration time was 12 h, the aeration stirring was started after the addition of the supernatant of the centrifugal liquid, the aeration amount was 1.6 L / min, and the magnetic stirring speed was 300 r / min.

[0075] Example 6

[0076] The sludge produced by the secondary sedimentation tank of a sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant was removed from the settled liquid, and the remaining material in the settled liquid was prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.08 g / gTS of PMS were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0077] The acid production of the sludge treated by steel slag combined with PMS was 321.8 mgCOD / gVS, and the VS removal rate was 44.3%.

[0078] The sludge produced by the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid and valeric acid as carbon sources, ammonium chloride as nitrogen source, and potassium dihydrogen phosphate as phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled at 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 with 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0079] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air volume was 70-90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min. After the supernatant was discharged during the effluent stage, an equal volume of artificial water was added during the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was measured every 15 days.

[0080] The ADF process was used for bacterial community acclimation and enrichment at 20°C.

[0081] The 125 mL PHA-producing bacteria mixture was used as inoculum, and the inoculum was pre-aerated for 1 h, and 310 mL supernatant of the centrifugal liquid was added. The aeration time was 12 h, and the aeration and stirring were started after the addition of the supernatant of the centrifugal liquid. The aeration amount was 1.4 L / min, and the magnetic stirring speed was 300 r / min.

[0082] Example Seven

[0083] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settling liquid. The supernatant in the settling liquid was removed, and the remaining substance in the settling liquid was prepared into a sludge sample with a concentration of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.11 g / gTS of PMS were added, and the mixture was shaken and stirred. After purging with nitrogen for 5 min, the serum bottle was sealed with a rubber plug and placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0084] The acid production amount of the sludge treated by steel slag combined with PMS was 336.0 mgCOD / gVS, and the VS removal rate was 45.4%.

[0085] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used. Acetic acid, propionic acid, butyric acid, and valeric acid were used as carbon sources, ammonium chloride was used as a nitrogen source, and potassium dihydrogen phosphate was used as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at a concentration of 0.5 mL / L, and thiourea was added at a concentration of 40 mg / L to inhibit nitrification.

[0086] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), settling stage (1.5 h), effluent stage (15 min), and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were simultaneously performed during the aeration stage, the air stirring air amount was 70-90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 100-120 r / min. After the supernatant was discharged during the effluent stage, an equal volume of artificial water was added during the influent stage. The influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacteria mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0087] The ADF process was used for bacterial community acclimation and enrichment at 20°C.

[0088] The PHA-producing bacteria mixture of 125 mL was used as inoculum, and the inoculum was pre-aerated for 1 h, and 310 mL of supernatant of the centrifugal liquid was added. The aeration time was 12 h, and the aeration was started after the addition of the supernatant of the centrifugal liquid. The aeration amount was 1.6 L / min, and the stirring speed was 300 r / min.

[0089] The PHA content in the sludge reached the maximum at 2 h of the synthesis reaction, and the maximum amount was 35.4 wt%, wherein the proportion of PHB in the PHA was 78%, and the proportion of PHV in the PHA was 22%.

[0090] The PHA crystals were obtained by using the chloroform-methanol precipitation method to extract the PHA in the initial sludge.

[0091] Example Eight

[0092] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settling liquid, the supernatant in the settling liquid was removed, and the remaining objects in the settling liquid were prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.14 g / gTS of PMS were added, and the serum bottle was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0093] The acid production amount of the sludge treated by the combination of steel slag and PMS was 306.2 mgCOD / gVS, and the VS removal rate was 42.8%.

[0094] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 3600 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid, and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 by using 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 mL / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0095] The operation cycle (12 h) of the ADF process: water feeding stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), water draining stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge discharge was performed. The aeration stage was performed by mechanical stirring and air stirring simultaneously, the air stirring air quantity was 70-90 L / h, the dissolved oxygen data was monitored on-line by a paperless recorder, the mechanical stirring speed was 100-120 r / min; after the supernatant was discharged in the water draining stage, an equal volume of artificial water was supplemented in the water feeding stage, the water feeding and water draining were controlled by a timer and a peristaltic pump, and the operation was cyclic; the hydraulic retention time was 1 d, and the sludge retention time was 10 d; the domestication and enrichment of the PHA-producing bacterial mixture generally required 45 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0096] The ADF process was used for bacterial community domestication and enrichment at 20℃.

[0097] 125 mL of the PHA-producing bacterial mixture was used as the seed sludge, the seed sludge was pre-aerated for 1 h, and 310 mL of the supernatant of the centrifugate was added. The aeration time was 12 h, the aeration stirring was started after the addition of the supernatant of the centrifugate, the aeration quantity was 1.6 L / min, and the magnetic stirring speed was 300 r / min.

[0098] Example Nine

[0099] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was allowed to stand and settle at 4℃ for 24 h to obtain a sedimentation liquid, the supernatant in the sedimentation liquid was removed, and the remaining substance in the sedimentation liquid was prepared into a sludge sample with a concentration of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag was added, and the mixture was shaken uniformly. After purging with nitrogen for 5 min, the serum bottle was sealed with a rubber plug and placed in a constant-temperature shaking incubator at 30℃ and 200 r / min for cultivation for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifugate.

[0100] The acid production amount of the sludge treated by the steel slag was 276.9 mgCOD / gVS, and the VS removal rate was 36.7%.

[0101] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 5000 mg / L, artificial water was used, acetic acid, propionic acid, butyric acid and valeric acid were used as carbon sources, ammonium chloride was used as a nitrogen source, and potassium dihydrogen phosphate was used as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1; the chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 by using 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 mL / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0102] The operation cycle (12h) of the ADF process: water feeding stage (15min), aeration stage (9h), sedimentation stage (1.5h), water draining stage (15min) and standby stage (1h). At the end of the aeration stage, sludge is discharged. The aeration stage is performed by mechanical stirring and air stirring simultaneously, the air stirring air volume is 90L / h, the dissolved oxygen data is monitored online by a paperless recorder, the mechanical stirring speed is 120r / min; after the supernatant is discharged in the water draining stage, an equal volume of artificial water is supplemented in the water feeding stage, the water feeding and water draining are controlled by a timer and a peristaltic pump, and the operation is cyclic; the hydraulic retention time is 1d, and the sludge retention time is 10d; the domestication and enrichment of the PHA-producing bacterial mixture generally needs 60 days, and the PHA content in the sludge in the enrichment reactor is measured every 15 days.

[0103] The ADF process is used for bacterial community domestication and enrichment at 22℃.

[0104] The supernatant of the centrifugal liquid is adjusted to pH 10 with 2mol / L sodium hydroxide, heated in a constant temperature water bath at 60-70℃, and simultaneously subjected to magnetic stirring for 3h to remove ammonia nitrogen, thereby obtaining a denitrified liquid. The denitrified liquid is adjusted to pH 8 and used as a carbon source.

[0105] 200mL of the PHA-producing bacterial mixture is used as the seed sludge, the seed sludge is pre-aerated for 1h, 200mL of the denitrified liquid with pH 8 is added per batch, 5 batches are used, the aerobic aeration and magnetic stirring are performed simultaneously for 1.5h, then the aeration and magnetic stirring are stopped, the sludge is allowed to settle, 200mL of the supernatant is removed, and the next batch is started. This cycle is repeated for 5 batches.

[0106] The batch cycle operation is realized by a four-magnetic-stirring device and an aeration device, and the dissolved oxygen at the start and end of each batch is monitored online. The reaction temperature is 22℃, the aeration volume is controlled to be 1.6L / min by an air flow meter, and the stirring speed is 300r / min. The PHA content in the sludge is measured by sampling at the start and end of each batch.

[0107] The PHA content in the sludge reaches the maximum at the 5th batch of the synthesis reaction, and the maximum amount is 41.2wt%, wherein the PHB accounts for 76% of the PHA, and the PHV accounts for 24% of the PHA.

[0108] The PHA in the sludge is extracted by a chloroform-methanol precipitation method to obtain PHA crystals.

[0109] Example Ten

[0110] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant of the settled liquid was removed, and the remaining substance in the settled liquid was prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.11 g / gTS of PMS was added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and then placed in a constant temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0111] The sludge produced by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used as the carbon source, with acetic acid, propionic acid, butyric acid and valeric acid as the carbon sources, ammonium chloride as the nitrogen source, and potassium dihydrogen phosphate as the phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled at 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 with 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0112] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), settling stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air volume was 90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 120 r / min. After the supernatant was discharged in the effluent stage, an equal volume of artificial water was added in the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 60 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0113] The ADF process was used for bacterial community acclimation and enrichment at 22°C.

[0114] The pH value of the supernatant of the centrifugal liquid was adjusted to 10 with 2 mol / L sodium hydroxide, and heated in a constant temperature water bath at 60°C while being stirred magnetically for 3 h to remove ammonia nitrogen, to obtain a denitrified liquid. The pH value of the denitrified liquid was adjusted to 8 for use as a carbon source.

[0115] The 200 mL PHA-producing bacterial mixture was used as inoculum, and the inoculum was pre-aerated for 1 h. 200 mL of denitrification liquid with pH 8 was added to each batch. The aerobic aeration and magnetic stirring were performed simultaneously for 1.5 h. After the process, the aeration and magnetic stirring were stopped, and the supernatant was removed by static settling. The process was repeated for 5 batches.

[0116] The batch cycle was achieved by using a four-magnetic stirrer and an aeration device, and the DO at the beginning and end of each batch was monitored online. The reaction temperature was 22°C, the aeration amount was controlled by an air flow meter at 1.6 L / min, and the stirring speed was 300 r / min. Samples were taken at the beginning and end of each batch, and the PHA content in the sludge was determined.

[0117] Example Eleven

[0118] The sludge produced in the secondary sedimentation tank of a wastewater treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a sedimentation liquid. The supernatant in the sedimentation liquid was removed, and the remaining material in the sedimentation liquid was prepared into a 15 g / L sludge sample. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / g TS of steel slag and 0.02 g / g TS of PM S were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a 30°C, 200 r / min constant temperature incubator for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifugate.

[0119] The sludge produced in the secondary sedimentation tank of a wastewater treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used. Acetic acid, propionic acid, butyric acid, and valeric acid were used as carbon sources, ammonium chloride was used as a nitrogen source, and potassium dihydrogen phosphate was used as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled at 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 ml / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0120] The operation cycle (12h) of the ADF process: water feeding stage (15min), aeration stage (9h), sedimentation stage (1.5h), water draining stage (15min) and standby stage (1h). At the end of the aeration stage, sludge discharge is performed. The aeration stage is performed by mechanical stirring and air stirring simultaneously, the air stirring air quantity is 90L / h, the dissolved oxygen data is monitored online by a paperless recorder, the mechanical stirring speed is 120r / min; after the supernatant is discharged in the water draining stage, an equal volume of artificial water is supplemented in the water feeding stage, the water feeding and water draining are controlled by a timer and a peristaltic pump, and the operation is cyclic; the hydraulic retention time is 1d, and the sludge retention time is 10d; the domestication and enrichment of the PHA-producing bacterial mixture generally need 60 days, and the PHA content in the sludge in the enrichment reactor is measured every 15 days.

[0121] The ADF process is used for bacterial community domestication and enrichment at 22℃.

[0122] The supernatant of the centrifugal liquid is adjusted to pH 10 by 2mol / L sodium hydroxide, heated in a constant temperature water bath at 60℃, and magnetically stirred at the same time, for 3h to remove ammonia nitrogen, to obtain a denitrification liquid, and the denitrification liquid is adjusted to pH 8 for carbon source use.

[0123] 200mL of the PHA-producing bacterial mixture is used as the seed sludge, the seed sludge is pre-aerated for 1h, 200mL of the denitrification liquid with pH 8 is added for each batch, 5 batches are used, the aerobic aeration and magnetic stirring are performed simultaneously for 1.5h, then the aeration and magnetic stirring are stopped, static sedimentation is performed, 200mL of supernatant is discharged, and then the next batch is entered. This cycle is repeated for 5 batches.

[0124] The batch cycle operation is realized by a four-magnetic-stirring device and an aeration device, and the DO at the beginning and end of each batch is monitored online. The reaction temperature is 22℃, the aeration quantity is controlled to be 1.6L / min by an air flow meter, and the stirring speed is 300r / min. Sampling is performed at the beginning and end of each batch, and the PHA content in the sludge is determined.

[0125] Example Twelve

[0126] The sludge generated in the secondary sedimentation tank of a sewage treatment plant is placed for static sedimentation at 4℃ for 24h to obtain a sedimentation liquid, the supernatant in the sedimentation liquid is removed, and the remaining substance in the sedimentation liquid is prepared into a 15g / L sludge sample. 450ml of the sludge sample is added into a serum bottle for fermentation, 0.3g / gTS of steel slag and 0.05g / gTS of PM S are added, stirred, purged with nitrogen for 5min, sealed with a rubber plug, and placed in a constant temperature shaking incubator at 30℃ and 200r / min for 9d to obtain a fermentation liquid. The fermentation liquid is centrifuged at 6000r / min for 15min to obtain a centrifugal liquid.

[0127] The sludge from the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid, and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the influent pH was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0128] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min), and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were performed simultaneously during the aeration stage, the air stirring air volume was 90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 120 r / min. After the supernatant was discharged during the effluent stage, an equal volume of artificial water was supplemented during the influent stage. The influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 60 days, and the PHA content in the sludge in the enrichment reactor was measured every 15 days.

[0129] The ADF process was used for bacterial community acclimation and enrichment at 22°C.

[0130] The pH of the supernatant of the centrifuged liquid was adjusted to 10 using 2 mol / L sodium hydroxide, and the liquid was heated in a constant temperature water bath at 60°C while being magnetically stirred for 3 h to remove ammonia nitrogen, thereby obtaining a denitrified liquid. The denitrified liquid was adjusted to a pH of 8 and used as a carbon source.

[0131] The 200 mL PHA-producing bacterial mixture was used as inoculum and pre-aerated for 1 h. 200 mL of denitrified liquid with a pH of 8 was added to each batch. The aerobic aeration and magnetic stirring were performed simultaneously for 1.5 h, after which the aeration and magnetic stirring were stopped, and the supernatant was removed. The process was repeated for 5 batches.

[0132] The batch cycle was achieved by a four-magnet stirrer and an aeration device, and the DO at the beginning and end of each batch was monitored online. The reaction temperature was 22°C, the aeration amount was controlled at 1.6 L / min using an air flow meter, and the stirring speed was 300 r / min. Samples were taken at the beginning and end of each batch, and the PHA content in the sludge was determined.

[0133] Example XIII

[0134] The sludge generated by the secondary sedimentation tank of the sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant in the settled liquid was removed, and the remaining objects in the settled liquid were prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / g TS of steel slag and 0.08 g / g TS of PM S were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and then placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0135] The sludge generated by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 with 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 mL / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0136] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air volume was 90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 120 r / min. After the supernatant was discharged in the effluent stage, an equal volume of artificial water was added in the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 60 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0137] The ADF process was used for bacterial community acclimation and enrichment at 22°C.

[0138] The pH value of the supernatant of the centrifugal liquid was adjusted to 10 with 2 mol / L sodium hydroxide, and the liquid was heated in a constant-temperature water bath at 60-70°C while being stirred magnetically for 3 h to remove ammonia nitrogen, thereby obtaining a denitrified liquid. The denitrified liquid was adjusted to a pH of 8 and used as a carbon source.

[0139] The 200 mL PHA-producing bacterial mixture was used as inoculum, and the inoculum was pre-aerated for 1 h. 200 mL of denitrification liquid with pH 8 was added to each batch. The aerobic aeration and magnetic stirring were performed simultaneously for 1.5 h. After the process, the aeration and magnetic stirring were stopped, and the supernatant was removed by static settling. The process was repeated for 5 batches.

[0140] The batch cycle was achieved by using a four-magnetic stirrer and an aeration device, and the DO at the beginning and end of each batch was monitored online. The reaction temperature was 22°C, the aeration amount was controlled by an air flow meter at 1.6 L / min, and the magnetic stirring speed was 300 r / min. Samples were taken at the beginning and end of each batch, and the PHA content was determined.

[0141] Example Fourteen

[0142] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a sedimentation liquid. The supernatant in the sedimentation liquid was removed, and the remaining material in the sedimentation liquid was prepared into a 15 g / L sludge sample. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / g TS of steel slag and 0.11 g / g TS of PMS were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and placed in a constant temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquid. The fermentation liquid was centrifuged at 6000 r / min for 15 min to obtain a centrifuged liquid.

[0143] The sludge generated in the secondary sedimentation tank of a sewage treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used. Acetic acid, propionic acid, butyric acid, and valeric acid were used as carbon sources, ammonium chloride was used as a nitrogen source, and potassium dihydrogen phosphate was used as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled at 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at 0.5 mL / L, and thiourea was added at 40 mg / L to inhibit nitrification.

[0144] The operation cycle (12h) of the ADF process: water feeding stage (15min), aeration stage (9h), sedimentation stage (1.5h), water draining stage (15min) and standby stage (1h). At the end of the aeration stage, sludge is discharged. The aeration stage is carried out by mechanical stirring and air stirring simultaneously, the air stirring air volume is 90L / h, the dissolved oxygen data is monitored online by a paperless recorder, the mechanical stirring speed is 120r / min; after the supernatant is discharged in the water draining stage, an equal volume of artificial water is supplemented in the water feeding stage, the water feeding and water draining are controlled by a timer and a peristaltic pump, and the operation is cyclic; the hydraulic retention time is 1d, and the sludge retention time is 10d; the domestication and enrichment of the PHA-producing bacterial mixture generally needs 60 days, and the PHA content in the sludge in the enrichment reactor is measured every 15 days.

[0145] The ADF process is used for bacterial community domestication and enrichment at 22℃.

[0146] The supernatant of the centrifugal liquid is adjusted to pH 10 with 2mol / L sodium hydroxide, heated in a constant temperature water bath at 60℃, and simultaneously subjected to magnetic stirring for 3h to remove ammonia nitrogen, to obtain a denitrified liquid. The denitrified liquid is adjusted to pH 8 and used as a carbon source.

[0147] 200mL of the PHA-producing bacterial mixture is used as the seed sludge, and the seed sludge is pre-aerated for 1h. 200mL of the denitrified liquid with pH 8 is added in each batch, 5 batches are used, the aerobic aeration and magnetic stirring are carried out simultaneously for 1.5h, then the aeration and magnetic stirring are stopped, and the supernatant is removed by static settling, and then the next batch is started. This cycle is repeated for 5 batches.

[0148] The batch cycle operation is realized by a four-magnetic stirrer and an aeration device, and the DO at the beginning and end of each batch is monitored online. The reaction temperature is 22℃, the aeration amount is controlled by an air flow meter to be 1.6L / min, and the magnetic stirring speed is 300r / min. Sampling is carried out at the beginning and end of each batch, and the PHA content in the sludge is determined.

[0149] The PHA content in the sludge reaches the maximum in the 5th batch of the synthesis reaction, and the maximum amount is 62.9wt%, wherein the PHB proportion in PHA is 85.7%, and the PHV proportion is 14.3%.

[0150] The PHA in the sludge is extracted by a chloroform-methanol precipitation method to obtain PHA crystals.

[0151] Example Fifteen

[0152] The sludge generated by the secondary sedimentation tank of the sewage treatment plant was allowed to stand and settle at 4°C for 24 h to obtain a settled liquid, the supernatant of the settled liquid was removed, and the remaining substance in the settled liquid was prepared into a sludge sample of 15 g / L. 450 ml of the sludge sample was added to a serum bottle for fermentation, 0.3 g / gTS of steel slag and 0.14 g / gTS of PM S were added, and the mixture was shaken, purged with nitrogen for 5 min, sealed with a rubber plug, and then placed in a constant-temperature shaking incubator at 30°C and 200 r / min for 9 days to obtain a fermentation liquor. The fermentation liquor was centrifuged at 6000 r / min for 15 min to obtain a centrifugal liquid.

[0153] The sludge generated by the secondary sedimentation tank of the sewage treatment plant was inoculated at a concentration of 5000 mg / L, and artificial water was used, with acetic acid, propionic acid, butyric acid and valeric acid as carbon sources, ammonium chloride as a nitrogen source, and potassium dihydrogen phosphate as a phosphorus source. The proportion of acetic acid was 50.37%, the proportion of propionic acid was 11.89%, the proportion of butyric acid was 21.95%, and the proportion of valeric acid was 15.79%. The mass ratio of C:N:P was controlled to be 100:6:1. The chemical oxygen demand of the influent was 1000-1200 mg / L, the pH of the influent was adjusted to 8 using 2M sodium hydroxide, trace element nutrient solution was added at a dosage of 0.5 mL / L, and thiourea was added at a dosage of 40 mg / L to inhibit nitrification.

[0154] The operation cycle (12 h) of the ADF process: influent stage (15 min), aeration stage (9 h), sedimentation stage (1.5 h), effluent stage (15 min) and standby stage (1 h). At the end of the aeration stage, sludge was discharged. Mechanical stirring and air stirring were carried out simultaneously during the aeration stage, the air stirring air quantity was 90 L / h, the dissolved oxygen data was monitored online by a paperless recorder, and the mechanical stirring speed was 120 r / min. After the supernatant was discharged in the effluent stage, an equal volume of artificial water was added in the influent stage, and the influent and effluent were controlled by a timer and a peristaltic pump, and the operation was cyclic. The hydraulic retention time was 1 d, and the sludge retention time was 10 d. The acclimation and enrichment of the PHA-producing bacterial mixture generally required 60 days, and the PHA content in the sludge in the enrichment reactor was determined every 15 days.

[0155] The ADF process was used for bacterial community acclimation and enrichment at 22°C.

[0156] The pH value of the supernatant of the centrifugal liquid was adjusted to 10 with 2 mol / L sodium hydroxide, and the liquid was heated in a constant-temperature water bath at 60°C while being stirred magnetically for 3 h to remove ammonia nitrogen, thereby obtaining a denitrified liquid. The denitrified liquid was adjusted to a pH of 8 and used as a carbon source.

[0157] The 200 mL PHA-producing bacteria mixed solution was used as seed sludge, the seed sludge was pre-aerated for 1 h, 200 mL denitrification liquid with pH value of 8 was added in each batch, 5 batches were adopted, aerobic aeration and magnetic stirring were simultaneously conducted for 1.5 h, after the end, the aeration and magnetic stirring were stopped, static sedimentation was conducted, 200 mL supernatant was discharged, and then the next batch was entered. The above cycle was repeated for 5 batches.

[0158] The batch cycle operation was realized through the quadruple magnetic stirrer and aeration device, and the DO at the beginning and end of each batch was monitored on line. The reaction temperature was 22°C, the aeration amount was controlled to be 1.6 L / min by using an air flow meter, and the magnetic stirring speed was 300 r / min. Sampling was conducted at the beginning and end of each batch, and the PHA content in the sludge was determined.

[0159] The above examples only describe the preferred embodiments of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A combined pretreatment of sludge and acidogenesis enhancement method, characterized by, It comprises: S1, the sludge generated by the secondary sedimentation tank of the sewage treatment plant is allowed to stand and settle at a first set temperature for a first set time to obtain a settling liquid; S2, removing the supernatant in the settling liquid, and preparing the remaining objects in the settling liquid into a sludge sample with a set total solid concentration; the ratio of the volatile solid concentration to the total solid concentration of the sludge sample is greater than a set ratio; the set ratio is 0.5; S3, adding steel slag and potassium peroxymonosulfate composite salt in the sludge sample, and anaerobic fermentation at a second set temperature for a second set time to obtain a fermentation liquid; the addition amount of the steel slag is 0.3-0.5g / gTS, and the addition amount of the potassium peroxymonosulfate composite salt is 0.02-0.14g / gTS; S4, centrifuging the fermentation liquid to obtain a centrifugal liquid; the supernatant of the centrifugal liquid is rich in volatile fatty acids.

2. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The set total solid concentration is 12-15g / L.

3. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The second set time is 9-12 days.

4. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The first set temperature is 4℃.

5. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The first set time is greater than or equal to 24h.

6. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The second set temperature is 29-31℃.

7. The combined pretreatment of sludge and acid production enhancement method according to claim 1, characterized by, The volatile fatty acids include acetic acid, propionic acid, isobutyric acid, butyric acid, isoamyl acid and valeric acid; The proportion of acetic acid is 46.28-50.37%, the proportion of propionic acid is 11.89-14.52%, the proportion of isobutyric acid is 5.07-8.05%, the proportion of butyric acid is 3.43-15.95%, the proportion of isoamyl acid is 11.00-15.51%, and the proportion of valeric acid is 1.71-4.74%.

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