Preparation method of phosphoric acid-calcium-based sludge carbon for in-situ culture of continuous flow aerobic granular sludge

Abstract

According to the preparation method of the phosphoric acid-calcium-based sludge carbon for in-situ culture of the continuous flow aerobic granular sludge, the sludge carbon is treated by using phosphoric acid and calcium hypochlorite, and the phosphoric acid-calcium-based sludge carbon has surface wrinkles, a large number of oxygen-containing functional groups and lower Zeta potential; in-situ rapid formation of the continuous-flow aerobic granular sludge is regulated and induced through combined regulation and control of phosphoric acid-calcium-based sludge carbon and regular sludge discharge measures, popularization and application of a continuous-flow aerobic granular sludge process are facilitated, the formation time of the continuous-flow aerobic granular sludge is shortened, a new way is provided for culture of the continuous-flow aerobic granular sludge, and the method is suitable for large-scale popularization and application of the continuous-flow aerobic granular sludge. And the theoretical technical bottleneck of aerobic granular sludge application is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of biological sewage treatment and relates to a method for preparing phosphate-calcium based sludge carbon for in-situ cultivation of continuous flow aerobic granular sludge. Background Art

[0002] Aerobic granular sludge (AGS) has high microbial biomass, tight structure, fast sedimentation rate and high solid concentration. It can save the large secondary sedimentation tank and energy-consuming return facilities. It can not only remove carbon, nitrogen, phosphorus and other pollutants at the same time, but also reduce the floor space by 75%, reduce the operating cost by about 35%, and save about 50% of energy consumption. It is considered to be one of the most promising water treatment technologies. However, the difficulty in rapid granulation and maintaining long-term stable operation is the core bottleneck that hinders its popularization and development.

[0003] So far, aerobic sludge granulation has mostly been successful only in sequencing batch reactors (SBR), and the cultivation time usually takes 50 to 70 days. At present, the continuous flow system is still the mainstream treatment process. Compared with transforming the existing continuous flow system into SBR, cultivating AGS in the existing continuous flow infrastructure can significantly reduce the transformation cost and has more research value and application potential. However, the in-situ cultivation of aerobic granular sludge under the continuous flow system is a key breakthrough point; the long granulation time and poor stability are the key technical bottlenecks.

[0004] At present, there are a lot of literature reports on the related research on promoting the rapid formation of aerobic granular sludge, but they all promote the rapid formation of aerobic granular sludge through inoculation of seed sludge, sedimentation selection pressure, hydraulic shear force, poor-rich nutrient alternation, addition of carriers, engineering strains and other control strategies. The sedimentation performance of sludge is poor in the initial operation, and it takes about 30 days to achieve complete granulation. Zou Jinte et al. applied for a method to promote the rapid formation of aerobic granular sludge through the preparation of sludge aggregates. The sludge aggregates were prepared by chitosan modification and pH adjustment. The preparation process is relatively cumbersome, and the successful cultivation of aerobic granular sludge was only achieved in the SBR system. Whether it can be achieved in the continuous flow system is still unknown. This may be related to the fact that there are many influencing factors in the cultivation of AGS in the continuous flow system, which is not easy to effectively control and the granulation time is long.

[0005] Therefore, it is necessary to find an economical, stable and efficient method to enable the rapid in-situ cultivation of aerobic granular sludge under a continuous flow system, so that the system has good sedimentation performance at the initial start-up and can operate stably for a long time. This has very important practical significance and economic value for the engineering application of aerobic granular sludge technology in the field of wastewater treatment. Summary of the invention

[0006] The purpose of the present invention is to provide a phosphate-calcium-based sludge carbon, which is suitable for strengthening the in-situ cultivation of continuous flow aerobic granular sludge, using phosphate-calcium-based sludge carbon as a crystal nucleus to induce microbial attachment and aggregation in situ, enhance the microbial sedimentation performance, and shorten the continuous flow aerobic granular sludge cultivation time, thereby solving the problem that continuous flow aerobic granular sludge is difficult to cultivate in situ.

[0007] The purpose of the present invention is achieved through the following technical solutions: A phosphate-calcium-based sludge carbon for continuous flow aerobic granular sludge in-situ cultivation, the preparation method of which comprises the following steps: The sludge cake obtained after concentration and dehydration in the secondary sedimentation tank of the sewage treatment plant is mixed with a phosphoric acid solution, and stirred uniformly at room temperature for 24 to 48 hours to obtain a mixed solution; the mixed solution is centrifuged and then dried to obtain phosphoric acid-modified sludge carbon; the mass volume ratio of the sludge cake to the phosphoric acid solution is 1:45 to 100; the phosphoric acid concentration is 1 to 3 mol / L; The phosphoric acid-modified sludge carbon and the calcium hypochlorite solution are stirred and mixed, subjected to hydrothermal reaction at 55-65° C. for 2 to 6 hours, washed to adjust the pH value to neutral, centrifuged and dried to obtain the phosphate-calcium-based sludge carbon; the mass volume ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution is 1:15-40; and the concentration of the calcium hypochlorite solution is 0.1%-1%.

[0008] As a more optimal technical solution of the present invention, the mass volume ratio of the sludge cake to the phosphoric acid solution is 1:50.

[0009] As a more optimal technical solution of the present invention, the mass volume ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution is 1:20.

[0010] As a more optimal technical solution of the present invention, the phosphoric acid concentration is 1 mol / L.

[0011] As a more optimal technical solution of the present invention, the concentration of the calcium hypochlorite solution is 0.4%.

[0012] As a more optimal technical solution of the present invention, the hydrothermal reaction is carried out at 55-65°C in the hydrothermal reactor.

[0013] Another object of the present invention is to provide a continuous flow aerobic granular sludge in situ culture method, comprising the following steps: Inoculate aeration tank sludge to make the initial sludge concentration in the continuous flow reactor reach 3000~4000mg / L; Add phosphate-calcium-based sludge carbon at a concentration of 1-5 g / L into the continuous flow reactor and mix it fully with the sludge in the system; The continuous flow reactor is operated at room temperature and mechanically stirred and aerated to achieve complete mixing of the flocculent activated sludge. Using actual domestic sewage as influent, the sewage enters the continuous flow reactor at room temperature; the residence time of the continuous flow reactor is 6-8 h, and the dissolved oxygen contents of the anaerobic tank, anoxic tank and aerobic tank are 0.2-0.5 mg / L, 0.5-0.7 mg / L and 2-4 mg / L respectively; The mixed liquor from the aerobic tank is returned to the anoxic tank for denitrification and nitrogen removal; the nitrification liquid return ratio is 200-300%; the sludge with good settling performance in the sedimentation tank is returned to the anaerobic tank, and the sludge with poor settling performance is discharged with the effluent; the sludge return ratio is 300-500%; no sludge discharge measures are taken for 20-30 days to allow microorganisms to gradually gather around the sludge carbon and gradually increase the sludge concentration of the reactor; a sludge discharge cycle of 5-7 days, 200-400 mL of sludge is discharged each time to maintain stable operation of the reactor; Every 90 days, powdered phosphate-calcium-based sludge carbon is added to the reaction system at a concentration of 0.1-0.5 g / L and regularly added to the aerobic tank; the particle size of the sludge carbon is 75-85 μm; After the continuous flow reactor was operated for 10 days, aerobic granular sludge growing around sludge carbon began to appear in the reactor.

[0014] The continuous flow reaction comprises A 2 / O, A / O or oxidation ditch continuous flow reaction.

[0015] Another object of the present invention is to provide a continuous flow aerobic granular sludge enhanced treatment system, comprising a liquid inlet barrel, a liquid inlet pipe, a peristaltic pump, A 2 / O reactor, sedimentation tank, liquid outlet pipe and liquid outlet barrel; The A 2 The / O reactor includes an anaerobic tank, an anoxic tank, an aerobic tank and an aeration unit; the microporous aeration head of the aeration unit is set at A 2 / O reactor; A 2 The initial sludge concentration in the A / O reactor is 3000~4000mg / L; the anaerobic tank and the anoxic tank are equipped with mechanical agitators and run at room temperature. 2 / O reactor, and mechanical stirring and aeration treatment are carried out to make the flocculent activated sludge reach a completely mixed state; a sampling port and a liquid discharge port are opened on the side; the liquid inlet tank is connected to A 2 / O reactor’s liquid inlet is connected, and a peristaltic pump is connected to the liquid inlet pipe to supply liquid to A 2 / O reactor inlet water, using actual domestic sewage as inlet water, the sewage enters A under room temperature 2 / O reactor; the water quality of the inlet water is: COD concentration is 100~300mg / L, ammonia nitrogen concentration is 20~40mg / L, total nitrogen concentration is 20~40mg / L, total phosphorus concentration is 20~30mg / L, pH is 7.0~8.5; A2 The residence time of the / O reactor is 5~8h, and the dissolved oxygen contents of the anaerobic tank, anoxic tank and aerobic tank are 0.2~0.5mg / L, 0.5~0.7mg / L and 2~4mg / L respectively; part of the mixed liquid in the aerobic tank is returned to the anoxic tank for denitrification; the sludge with good settling performance in the sedimentation tank is returned to the anaerobic tank, and the sludge with poor settling performance is discharged with the effluent; wait for A 2 After the A / O reactor runs stably, add phosphate-calcium-based sludge carbon solution into the aerobic tank; 2 / O reactor runs for 7~14 days; the outlet pipe is connected to A 2 / O The drain port of the reactor is connected to drain water into the liquid outlet bucket.

[0016] The beneficial effects are as follows: The preparation method provided by the present invention uses phosphoric acid and calcium hypochlorite to treat sludge carbon, and the addition of phosphate-calcium-based sludge carbon and regular sludge discharge measures are combined to regulate and induce the in-situ rapid formation of continuous flow aerobic granular sludge, which is conducive to the promotion and application of the continuous flow aerobic granular sludge process.

[0017] The phosphate-calcium-based sludge carbon prepared by the present invention has surface wrinkles, a large number of oxygen-containing functional groups and a lower Zeta potential, which makes it have great advantages in microbial aggregation. The time for the formation of continuous flow aerobic granular sludge is shortened, and the aerobic granular sludge can be cultivated in situ 10 days after the reactor is started, and good sludge settling performance is obtained, which is conducive to the stable operation of the aerobic granular sludge system, providing a new way for the cultivation of continuous flow aerobic granular sludge and solving the theoretical and technical bottleneck of the application of aerobic granular sludge.

[0018] The preparation method of the present invention is easy to operate, the materials involved are relatively convenient to prepare, the cost is low, and only a small amount of sludge carbon needs to be added to achieve a strong speed-enhancing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Scanning electron microscope (SEM) images of the unmodified dehydrated water cake and phosphate-calcium based sludge carbon prepared in Example 1 and Example 15.

[0020] Figure 2 Fourier transform infrared spectra (FT-IR) of the unmodified dehydrated water cake and phosphate-calcium based sludge carbon prepared in Example 1 and Example 15.

[0021] Figure 3 Zeta potential diagram of unmodified dehydrated water cake and phosphate-calcium based sludge carbon prepared in Example 1 and Example 15.

[0022] Figure 4 This is a graph showing the settling performance of flocculent sludge promoted by the unmodified dehydrated water cake prepared in Example 1 and Example 15 and the phosphate-calcium-based sludge carbon.

[0023] Figure 5 This is a schematic diagram of the system for in-situ cultivation of continuous flow aerobic granular sludge enhanced by adding sludge carbon powder. The continuous flow system mainly uses an A2 / O reactor.

[0024] Among them: 1. liquid inlet barrel, 2. liquid inlet pump, 3. anaerobic tank, 4. anoxic tank, 5. aerobic tank, 6. sedimentation tank, 7. microporous aeration head, 8. compressed air pump, 9. mechanical agitator, 10. sampling port, 11. liquid inlet, 12. sludge return inlet, 13. sludge return outlet, 14. mixed liquid return inlet, 15. mixed liquid return outlet, 16. liquid outlet, 17. liquid outlet barrel, 18. sludge carbon powder dosing device.

[0025] Figure 6 The microscopic images of aerobic granular sludge after culturing the sludge carbon prepared in Example 1 and Example 15 for 14 days.

[0026] Figure 7 This is a diagram showing the pollutant removal effect during the aerobic granular sludge cultivation process using the sludge carbon prepared in Example 1 and Example 15, including inlet and outlet water data diagrams of COD, phosphate and ammonia nitrogen. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention. Unless otherwise specified, the professional and scientific terms used in this article have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equal to the recorded content can also be applied to the present invention.

[0028] In addition, if no specific technical operation steps or conditions are specified in the examples, they are all carried out according to the general techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained through commercial purchase.

[0029] Example 1 A method for preparing phosphate-calcium based sludge carbon comprises the following steps: The dehydrated cake after dehydration and concentration of sewage plant sludge (water content to 61%) was mixed with a 1 mol / L phosphoric acid solution and stirred for 24 hours. The solid-liquid ratio of the cake to the phosphoric acid solution was 1 g: 50 mL. After centrifugation and drying at 50 ° C, it was ground and sieved to obtain phosphoric acid-modified sludge carbon. The phosphoric acid-modified sludge carbon was stirred with a 0.4% calcium hypochlorite solution for 30 minutes and then put into a reactor. The solid-liquid ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution was 1 g: 20 mL, and hydrothermally reacted at 60 ° C for 3 hours. After washing the mixed solution after the hydrothermal reaction and adjusting the pH value to neutral, it was centrifuged and dried at 50 ° C for 24 hours, and then ground and sieved to obtain powdered phosphate-calcium-based sludge carbon.

[0030] Example 2 The difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the mud cake to the phosphoric acid solution is 1 g:45 mL.

[0031] Example 3 The difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the mud cake to the phosphoric acid solution is 1 g:80 mL.

[0032] Example 4 The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of the mud cake to the phosphoric acid solution is 1 g:100 mL.

[0033] Example 5 The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of phosphoric acid-modified sludge carbon to calcium hypochlorite solution is 1 g:15 mL.

[0034] Example 6 The only difference between this embodiment and embodiment 1 is that the solid-liquid ratio of phosphoric acid-modified sludge carbon to calcium hypochlorite solution is 1 g:40 mL.

[0035] Example 7 The only difference between this embodiment and embodiment 1 is that the hydrothermal reaction is carried out for 2 hours.

[0036] Example 8 The only difference between this embodiment and embodiment 1 is that the hydrothermal reaction is carried out for 6 hours.

[0037] Example 9 The only difference between this embodiment and embodiment 1 is that the concentration of the phosphoric acid solution is 3 mol / L.

[0038] Example 10 The difference between this embodiment and embodiment 1 is only that the concentration of the calcium hypochlorite solution is 1%.

[0039] Embodiment 11 The difference between this embodiment and embodiment 1 is that the concentration of the calcium hypochlorite solution is 0.1%.

[0040] Example 12 The difference between this embodiment and embodiment 1 is that the phosphoric acid solution is replaced by water.

[0041] Example 13 The difference between this embodiment and embodiment 1 is that the sodium hypochlorite solution is replaced by water.

[0042] Application Examples A method for strengthening the use of phosphate-calcium-based sludge carbon 2 / O The method for in-situ formation of continuous flow aerobic granular sludge comprises the following steps: Powdered sulfate-calcium-based sludge carbon was added to the reactor, and the physical and chemical properties of the granular sludge in different reactors during the formation process were continuously observed. The physical properties included sludge morphology, sedimentation performance, sludge concentration and sludge particle size analysis, and the chemical properties included sludge secretion of EPS, sludge surface hydrophobicity, etc. By comparison, it can be intuitively explained that the addition of phosphate-calcium-based sludge carbon can accelerate the formation of aerobic granular sludge and realize the in-situ cultivation of continuous flow aerobic granular sludge, as follows: Build 15 identical sets of A 2 / O Continuous flow reactors run in parallel: R1-14 group is an experimental group, and the product prepared in Example 1-14 is added to the reactor in powder form after the reactor is in stable operation; R0 group is a blank group, without adding any materials.

[0043] The physical and chemical properties of the granular sludge in different reactors during the formation process were continuously observed. The physical properties included sludge morphology, sedimentation performance, sludge structure wet density and sludge particle size analysis, and the chemical properties included sludge secretion of EPS, sludge surface hydrophobicity, etc. The conventional indicators of sewage in the continuous flow system were measured every 3 days. The sampling time was after the mixed liquid of the aerobic tank was taken out and centrifuged for 5 minutes. The supernatant was used to measure the effluent water quality indicators. DO, pH and other indicators were measured using the national standard method.

[0044] The results of the control test are as follows: 1. Changes in morphology and structure Aerobic granular sludge appeared in the R1 group reactor on the 7th day, and the granules matured in 20-22 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0045] Aerobic granular sludge appeared in the R2 group reactor on the 8th day, and the granules matured in 21-24 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0046] Aerobic granular sludge appeared in the R3 group reactor on the 8th day, and the granules matured in 22-25 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0047] Aerobic granular sludge appeared in the R4 group reactor on the 8th day, and the granules matured in 27-30 days, with a particle size distribution of 0.7-1.8 mm. The particle structure was less compact than that of R1-3. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time.

[0048] Aerobic granular sludge appeared in the R5 group reactor on the 9th day, and the granules matured on the 25th to 29th day. The particle size distribution was 0.7 to 1.8 mm, and the particle structure was compact. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0049] Aerobic granular sludge appeared in the R6 group reactor on the 8th day, and the granules matured in 27-30 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0050] Aerobic granular sludge appeared in the R7 group reactor on the 7th day, and the granules matured in 22-25 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0051] Aerobic granular sludge appeared in the R8 group reactor on the 8th day, and the granules matured in 22-25 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0052] Aerobic granular sludge appeared in the R9 group reactor on the 9th day, and the granules matured in 27-30 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0053] Aerobic granular sludge appeared in the R10 group reactor on the 8th day, and the granules matured in 22-25 days, with a particle size distribution of 0.7-1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0054] Aerobic granular sludge appeared in the R11 group reactor on the 8th day, and the granules matured on the 23rd to 26th day, with a particle size distribution of 0.7 to 1.8 mm and a compact particle structure. 2 In the / O reactor, aerobic granular sludge can be formed in situ in a relatively short time and is well distributed.

[0055] Aerobic granular sludge with loose particle structure appeared in the R12 group reactor on the 40th day.

[0056] The R13 group reactor produced no granular sludge, but presented flocculent form.

[0057] Aerobic granular sludge with loose particle structure appeared in the R14 group reactor on the 45th day.

[0058] No granular sludge was produced in the R0 group reactor, and the sludge was in the form of flocs.

[0059] 2. Changes in Sedimentation Performance The settling velocity of mature aerobic granular sludge in the R1-14 group reactor is 30~80m / h, and the sludge index is 30~50mL / g; The sludge index in the R12 group reactor was 60~90mL / g; The sludge index of flocculent sludge in the R13 group reactor is 80~120mL / g; The sludge index of flocculent sludge in the R14 group reactor was 70~100mL / g; The sludge index of flocculent sludge in the R0 group reactor is 80~120mL / g.

[0060] The test results show that adding powdered sludge carbon into a continuous flow reactor has good aerobic granular sludge settling performance.

[0061] 3. Changes in chemical properties After the granular sludge matured, the COD removal rate, TN removal rate and TP removal rate were the best in the R1 group reactor. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R1 group reactor were 91%, 82% and 82%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R2 group reactor were 85%, 80% and 75%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R3 group reactor were 86%, 82% and 80%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R4 group reactor were 80%, 75% and 78%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R5 group reactor were 80%, 70% and 72%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R6 group reactor were 80%, 78% and 70%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R7 group reactor were 85%, 74% and 72%, respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R8 group reactor were 80%, 77% and 70% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R9 group reactor were 80%, 74% and 73% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R10 group reactor were 82%, 76% and 70% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R11 group reactor were 85%, 77% and 75% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R12 group reactor were 72%, 66% and 60% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R13 group reactor were 60%, 60% and 58% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R14 group reactor were 75%, 65% and 55% respectively. The COD removal rate, TN removal rate and TP removal rate at the highest point of the R15 group reactor were 65%, 60% and 55% respectively.

[0062] The continuous flow reactor involved in this embodiment is A 2 / O reactor, specific operating parameters: reactor dimensions length × width × height are 51 × 6 × 25 cm, the sedimentation tank height-to-diameter ratio is 4:1, and the total effective volume is 7.6 L.

[0063] Through the above control test results, the following conclusions can be drawn: The adsorption and conductivity of the phosphate-calcium-based sludge carbon powder prepared in Examples 1 to 11 accelerate the aggregation of sludge into large particles while promoting interspecies electron transfer, thereby forming aerobic granular sludge in 7 to 30 days, which is 40 to 70% shorter than the formation time of the traditional aerobic granular sludge process; the aerobic granular sludge based on the phosphate-calcium-based sludge carbon powder can reach a sludge concentration of more than 8000 mg / L after stabilization, has good sedimentation performance, and has a particle size distribution of 0.7 to 1.8 mm; the phosphate-calcium-based sludge carbon powder has more active sites, and the aerobic granular sludge system formed has an enhanced pollution removal effect compared with the conventional aerobic granular sludge process; the aerobic granular sludge culture time formed by the prepared phosphate-calcium-based sludge carbon powder is shortened, and the aerobic granular sludge system saves aeration volume and land compared with the conventional process, and can save 20 to 30% of energy consumption.

[0064] The physical and chemical properties of calcium-based sludge carbon were investigated. The microscopic morphology was observed using a scanning electron microscope, the surface functional groups were obtained using a Fourier transform infrared spectrometer, and the surface charge was investigated using a Zeta potential instrument. Figure 1 a It can be seen that the SEM image of the unmodified sludge carbon shows that the surface morphology is relatively flat and the pore structure is not obvious, while Figure 1 b shows that the surface of phosphate-calcium-based sludge carbon is damaged, and the surface of modified sludge carbon is wrinkled and has debris, which is conducive to the accumulation of microorganisms on the surface of biochar; Figure 2 The FT-TR graph in the middle shows that phosphate-calcium-based sludge carbon improves the response intensity of the corresponding functional groups, that is, it increases the number of oxygen-containing functional groups in the sludge; Figure 3 The Zeta potential showed that the surface charge of the sludge was neutralized after the phosphate-calcium salt pretreatment. The Zeta potential was neutralized from -22.14 mV to -12.13 mV, which was increased by 10.01 mV. The phosphate-calcium salt pretreatment neutralized part of the negative charge on the surface of the unmodified sludge carbon, which was beneficial to the aggregation of microorganisms. Figure 4 Medium SVI 10 It can be seen that the addition of phosphate-calcium-based sludge carbon can improve the settling performance of sludge, among which SVI 10 Increased by 13.09 mL / g.

[0065] The present invention constructs a continuous flow aerobic granular sludge rapid cultivation device based on phosphate-calcium-based sludge carbon powder. By adding phosphate-calcium-based sludge carbon powder, the formation speed of continuous flow aerobic granular sludge is significantly improved; the time of adding phosphate-calcium-based sludge carbon powder and not adding carbon powder involved in the present invention is shortened by 40-70%. The aerobic granular sludge obtained by the present invention has good stability after maturity, can withstand large impact loads, treats sewage water quality to reach Class A standard, improves the treatment capacity of conventional pollutants by 10%-30%, saves aeration volume and land compared with conventional aerobic granular sludge technology, and saves energy consumption by 20-30%.

[0066] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which will not affect the essence of the present invention.

Claims

1. A method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation, characterized in that: The steps include: The sludge cake obtained after concentration and dehydration in the secondary sedimentation tank of the sewage treatment plant is mixed with a phosphoric acid solution, and stirred uniformly at room temperature for 24 to 48 hours to obtain a mixed solution; the mixed solution is centrifuged and then dried to obtain phosphoric acid-modified sludge carbon; the mass volume ratio of the sludge cake to the phosphoric acid solution is 1:45 to 100; the phosphoric acid concentration is 1 to 3 mol / L; The phosphoric acid-modified sludge carbon and the calcium hypochlorite solution are stirred and mixed, subjected to hydrothermal reaction at 55-65° C. for 2 to 6 hours, washed to adjust the pH value to neutral, centrifuged and dried to obtain the phosphate-calcium-based sludge carbon; the mass volume ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution is 1:15-40; and the concentration of the calcium hypochlorite solution is 0.1%-1%.

2. The method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation according to claim 1, characterized in that: The mass volume ratio of the sludge cake to the phosphoric acid solution is 1:

50.

3. The method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation according to claim 1, characterized in that: The mass volume ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution is 1:

20.

4. The method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation according to claim 1, characterized in that: The phosphoric acid concentration is 1 mol / L.

5. The method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation according to claim 1, characterized in that: The concentration of the calcium hypochlorite solution is 0.1%.

6. The method for preparing phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation according to claim 1, characterized in that: Hydrothermal reaction was carried out at 55-65°C in a hydrothermal reactor.

7. A continuous flow aerobic granular sludge in situ culture method, characterized in that: The steps include: Inoculate aeration tank sludge to make the initial sludge concentration in the continuous flow reactor reach 3000~4000mg / L; Add phosphate-calcium-based sludge carbon at a concentration of 1-5 g / L into the continuous flow reactor and mix it fully with the sludge in the system; The continuous flow reactor is operated at room temperature and mechanically stirred and aerated to achieve complete mixing of the flocculent activated sludge. Using actual domestic sewage as influent, the sewage enters the continuous flow reactor at room temperature; the residence time of the continuous flow reactor is 6-8 h, and the dissolved oxygen contents of the anaerobic tank, anoxic tank and aerobic tank are 0.2-0.5 mg / L, 0.5-0.7 mg / L and 2-4 mg / L respectively; The mixed liquid from the aerobic tank flows back to the anoxic tank for denitrification and nitrogen removal; the nitrification liquid return ratio is 200-300%; the sludge with good settling performance in the sedimentation tank flows back to the anaerobic tank, and the sludge with poor settling performance is discharged with the effluent; The sludge return ratio is 300-500%. The reactor is operated for 20-30 days without sludge discharge, so that the microorganisms gradually gather around the sludge carbon and gradually increase the sludge concentration in the reactor. The sludge discharge cycle is 5-7 days, and 200-400 mL of sludge is discharged each time to maintain stable operation of the reactor. Every 90 days, powdered phosphate-calcium-based sludge carbon is added to the reaction system at a concentration of 0.1-0.5 g / L and regularly added to the aerobic tank; the particle size of the sludge carbon is 75-85 μm; After the continuous flow reactor was operated for 10 days, aerobic granular sludge growing around sludge carbon began to appear in the reactor.

8. The continuous flow aerobic granular sludge in situ culture method according to claim 7, characterized in that: Including A 2 / O, A / O or oxidation ditch continuous flow reaction.

9. A continuous flow aerobic granular sludge enhanced treatment system, characterized in that: Including liquid inlet barrel, liquid inlet pipe, peristaltic pump, A 2 / O reactor, sedimentation tank, liquid outlet pipe and liquid outlet barrel; The A 2 The / O reactor includes an anaerobic tank, an anoxic tank, an aerobic tank and an aeration unit; the microporous aeration head of the aeration unit is set at A 2 / O reactor; A 2 The initial sludge concentration in the A / O reactor is 3000~4000mg / L; the anaerobic tank and the anoxic tank are equipped with mechanical agitators and run at room temperature. 2 / O reactor, and mechanical stirring and aeration treatment are carried out to make the flocculent activated sludge reach a completely mixed state; a sampling port and a liquid discharge port are opened on the side; the liquid inlet tank is connected to A 2 / O reactor’s liquid inlet is connected, and a peristaltic pump is connected to the liquid inlet pipe to supply liquid to A 2 / O reactor inlet water, using actual domestic sewage as inlet water, the sewage enters A under room temperature 2 / O reactor; the water quality of the inlet water is: COD concentration is 100~300mg / L, ammonia nitrogen concentration is 20~40mg / L, total nitrogen concentration is 20~40mg / L, total phosphorus concentration is 20~30mg / L, pH is 7.0~8.5; A 2 The residence time of the / O reactor is 5~8h, and the dissolved oxygen contents of the anaerobic tank, anoxic tank and aerobic tank are 0.2~0.5mg / L, 0.5~0.7mg / L and 2~4mg / L respectively; part of the mixed liquid in the aerobic tank is returned to the anoxic tank for denitrification; the sludge with good settling performance in the sedimentation tank is returned to the anaerobic tank, and the sludge with poor settling performance is discharged with the effluent; wait for A 2 After the A / O reactor runs stably, add phosphate-calcium-based sludge carbon solution into the aerobic tank; 2 / O reactor runs for 7~14 days; the outlet pipe is connected to A 2 / O The drain port of the reactor is connected to drain water into the liquid outlet bucket.

10. A phosphate-calcium based sludge carbon for continuous flow aerobic granular sludge in situ cultivation, characterized in that: Prepared according to any preparation method described in claims 1 to 6.

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