A method for preparing phosphate-calcium-based sludge carbon for continuous flow aerobic granular sludge in situ cultivation

Abstract

The present invention provides a preparation method of calcium phosphate-based sludge carbon for in situ cultivation of continuous flow aerobic granular sludge. Phosphoric acid and calcium hypochlorite are used to treat the sludge carbon. The calcium phosphate-based sludge carbon has surface wrinkles, a large number of oxygen-containing functional groups and a lower Zeta potential. The addition of calcium phosphate-based sludge carbon and regular sludge discharge measures are combined to regulate and induce the rapid in situ formation of continuous flow aerobic granular sludge, which is conducive to the promotion and application of the continuous flow aerobic granular sludge process, shortens the formation time of the continuous flow aerobic granular sludge, provides a new way for the cultivation of continuous flow aerobic granular sludge, and solves the theoretical and technical bottlenecks of the application of aerobic granular sludge.

Description

Technical Field

[0001] The invention belongs to the technical field of sewage biological 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) boasts a high microbial biomass, a compact structure, rapid settling rates, and high solids concentrations. This eliminates the need for large secondary sedimentation tanks and energy-intensive recirculation facilities. It not only simultaneously removes pollutants such as carbon, nitrogen, and phosphorus, but also reduces footprint by 75%, lowers operating costs by approximately 35%, and saves approximately 50% of energy. It is considered one of the most promising water treatment technologies. However, difficulties in rapid granulation and maintaining long-term stable operation are key bottlenecks hindering its widespread adoption.

[0003] To date, aerobic sludge granulation has been largely successful only in sequencing batch reactors (SBRs), typically requiring 50-70 days of cultivation. However, continuous flow systems remain the dominant treatment process. Compared to converting existing continuous flow systems to SBRs, cultivating AGS within existing continuous flow infrastructure significantly reduces modification costs and offers greater research value and application potential. However, achieving in situ cultivation of aerobic granular sludge within continuous flow systems remains a key breakthrough; long granulation times and poor stability remain key technical bottlenecks.

[0004] Currently, there are numerous reports on research promoting the rapid formation of aerobic granular sludge. However, these studies all rely on regulatory strategies such as seed sludge inoculation, sedimentation selection pressure, hydraulic shear force, alternating between poor and rich nutrients, addition of carriers, and engineered bacterial strains to promote the rapid formation of aerobic granular sludge. Initially, the sludge has poor settling performance, and achieving complete granulation requires approximately 30 days. Zou Jinte et al. have applied for a method to promote the rapid formation of aerobic granular sludge by preparing sludge aggregates. These aggregates were prepared using chitosan modification and pH adjustment. The preparation process is relatively cumbersome, and successful cultivation of aerobic granular sludge was only achieved within an SBR system. Whether this can be achieved within a continuous flow system remains unknown. This may be due to the numerous factors affecting the cultivation of AGS in a continuous flow system, the difficulty in effectively controlling them, and the long granulation time.

[0005] Therefore, it is necessary to find an economical, stable and efficient method to enable aerobic granular sludge to be rapidly cultivated in situ under a continuous flow system, so that the system has good sedimentation performance at the initial startup 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. It uses phosphate-calcium-based sludge carbon as crystal nuclei 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:

[0008] A phosphate-calcium-based sludge carbon for continuous flow aerobic granular sludge in situ cultivation, the preparation method of which comprises the following steps:

[0009] 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 the mixture is uniformly stirred 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 concentration of the phosphoric acid is 1 to 3 mol / L;

[0010] 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%.

[0011] 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.

[0012] 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.

[0013] As a more optimal technical solution of the present invention, the phosphoric acid concentration is 1 mol / L.

[0014] As a more optimal technical solution of the present invention, the concentration of the calcium hypochlorite solution is 0.4%.

[0015] As a more optimal technical solution of the present invention, the hydrothermal reaction is carried out at 55-65°C in the hydrothermal reactor.

[0016] Another object of the present invention is to provide a continuous flow aerobic granular sludge in situ culture method comprising the following steps:

[0017] The aeration tank sludge was inoculated to make the initial sludge concentration in the continuous flow reactor reach 3000~4000mg / L;

[0018] Adding phosphate-calcium-based sludge carbon at a concentration of 1-5 g / L into the continuous flow reactor and fully mixing it with the sludge in the system;

[0019] The continuous flow reactor is operated at room temperature and mechanically stirred and aerated to achieve complete mixing of the flocculent activated sludge.

[0020] Using actual domestic sewage as influent, the sewage was fed into a continuous flow reactor at room temperature. The residence time of the continuous flow reactor was 6-8 hours, and the dissolved oxygen contents in the anaerobic tank, anoxic tank, and aerobic tank were 0.2-0.5 mg / L, 0.5-0.7 mg / L, and 2-4 mg / L, respectively.

[0021] 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 from 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 is adopted for operation for 20-30 days, allowing microorganisms to gradually accumulate around the sludge carbon and gradually increase the sludge concentration of the reactor; a sludge discharge cycle of 5-7 days is used, with 200-400 mL of sludge discharged each time to maintain stable operation of the reactor.

[0022] Powdered phosphate-calcium-based sludge carbon was added to the reaction system every 90 days at a concentration of 0.1-0.5 g / L and regularly added to the aerobic tank; the particle size of the sludge carbon was 75-85 μm;

[0023] After the continuous flow reactor was operated for 10 days, aerobic granular sludge began to appear in the reactor, growing around the sludge carbon.

[0024] The continuous flow reaction includes A 2 / O, A / O or oxidation ditch continuous flow reaction.

[0025] 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, and an A 2 / O reactor, sedimentation tank, liquid outlet pipe and liquid outlet barrel;

[0026] 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 3000~4000 mg / L; the anaerobic tank and the anoxic tank are equipped with mechanical stirrers 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 barrel is connected to the A 2 The liquid inlet of the A / O reactor is connected, and the liquid inlet pipe is connected to a peristaltic pump to supply A 2 / O reactor inlet, using actual domestic sewage as inlet, the sewage enters A under room temperature 2 / O reactor; the water quality of the inlet water is: COD concentration of 100~300mg / L, ammonia nitrogen concentration of 20~40mg / L, total nitrogen concentration of 20~40mg / L, total phosphorus concentration of 20~30mg / L, pH of 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 of 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 / O reactor runs stably, add phosphate-calcium-based sludge carbon solution into the aerobic tank; A 2 / O reactor runs for 7~14 days; the outlet pipe is connected to A 2 The drain port of the / O reactor is connected to the liquid outlet tank for drainage.

[0027] The beneficial effects are as follows:

[0028] 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 jointly regulated to 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.

[0029] The calcium-phosphate sludge carbon prepared by this method features surface wrinkles, a high number of oxygen-containing functional groups, and a lower zeta potential, giving it significant advantages in microbial aggregation. This shortens the time it takes to form continuous-flow aerobic granular sludge and enables in-situ cultivation of aerobic granular sludge as early as 10 days after reactor startup, achieving excellent sludge settling performance and facilitating the stable operation of the aerobic granular sludge system. This provides a new approach to cultivating continuous-flow aerobic granular sludge and addresses the theoretical and technical bottlenecks in its application.

[0030] The preparation method of the present invention is simple 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

[0031] Figure 1 These are scanning electron microscope (SEM) images of the unmodified dehydrated water cake and calcium phosphate-based sludge carbon prepared in Example 1 and Example 15.

[0032] Figure 2 Fourier transform infrared (FT-IR) spectra of the unmodified dehydrated cake and phosphate-calcium-based sludge carbon prepared in Example 1 and Example 15.

[0033] Figure 3 Zeta potential diagram of the unmodified dehydrated water cake and phosphate-calcium based sludge carbon prepared in Example 1 and Example 15.

[0034] Figure 4 This is a graph showing the settling performance of flocculent sludge promoted by the unmodified dehydrated water cake and phosphate-calcium-based sludge carbon prepared in Example 1 and Example 15.

[0035] 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.

[0036] 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.

[0037] Figure 6 The following are microscopic images of aerobic granular sludge after 14 days of cultivation using the sludge carbon prepared in Example 1 and Example 15.

[0038] Figure 7 This is a diagram showing the pollutant removal effect during the cultivation of aerobic granular sludge using the sludge carbon prepared in Example 1 and Example 15, including inlet and outlet water data of COD, phosphate and ammonia nitrogen. DETAILED DESCRIPTION

[0039] The technical solutions of the present invention will be described clearly and completely below in conjunction with the embodiments. Obviously, the embodiments described are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. Unless otherwise specified, the professional and scientific terms used herein have the same meanings as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to the described contents may also be applied to the present invention.

[0040] In addition, if no specific technical operation steps or conditions are specified in the examples, they were all carried out according to the general techniques or conditions described in the literature in this field or according to the product instructions. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0041] Example 1

[0042] A method for preparing calcium phosphate-based sludge carbon comprises the following steps:

[0043] The dehydrated cake from sewage 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, the mixture 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 placed in a reactor. The solid-liquid ratio of the phosphoric acid-modified sludge carbon to the calcium hypochlorite solution was 1 g:20 mL. The mixture was hydrothermally reacted at 60°C for 3 hours. The mixture was washed and the pH value was adjusted to neutral. The mixture was then centrifuged and dried at 50°C for 24 hours. The mixture was ground and sieved to obtain powdered phosphate-calcium sludge carbon.

[0044] Example 2

[0045] 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:45 mL.

[0046] Example 3

[0047] 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:80 mL.

[0048] Example 4

[0049] 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.

[0050] Example 5

[0051] 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.

[0052] Example 6

[0053] 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.

[0054] Example 7

[0055] The only difference between this embodiment and embodiment 1 is that the hydrothermal reaction is carried out for 2 hours.

[0056] Example 8

[0057] The only difference between this embodiment and embodiment 1 is that the hydrothermal reaction is carried out for 6 hours.

[0058] Example 9

[0059] The only difference between this embodiment and embodiment 1 is that the concentration of the phosphoric acid solution is 3 mol / L.

[0060] Example 10

[0061] The only difference between this embodiment and embodiment 1 is that the concentration of the calcium hypochlorite solution is 1%.

[0062] Example 11

[0063] The only difference between this embodiment and embodiment 1 is that the concentration of the calcium hypochlorite solution is 0.1%.

[0064] Example 12

[0065] The only difference between this embodiment and embodiment 1 is that water is used instead of the phosphoric acid solution.

[0066] Example 13

[0067] The only difference between this embodiment and embodiment 1 is that water is used instead of the sodium hypochlorite solution.

[0068] Application Examples

[0069] A phosphate-calcium-based sludge carbon-based enhanced A 2 / O continuous flow aerobic granular sludge in situ formation method, comprising the following steps:

[0070] Powdered sulfate-calcium-based sludge carbon was added to the reactor, and the physical and chemical properties of the granular sludge during formation in different reactors were continuously observed. The physical properties included sludge morphology, settling performance, sludge concentration, and sludge particle size analysis, while the chemical properties included sludge secretion of EPS and sludge surface hydrophobicity. Through comparison, it can be intuitively demonstrated that the addition of phosphate-calcium-based sludge carbon can accelerate the formation of aerobic granular sludge and achieve in-situ cultivation of continuous flow aerobic granular sludge, as follows:

[0071] Build 15 identical sets of A 2 / O Continuous flow reactors run in parallel:

[0072] R1-14 group is the experimental group, and after the reactor is running stably, the product prepared in Example 1-14 is added into the reactor in powder form;

[0073] R0 group is a blank group, and no materials are added.

[0074] The physical and chemical properties of the granular sludge in the various reactors were continuously observed during the formation process. Physical properties included sludge morphology, settling performance, wet density, and particle size analysis. Chemical properties included EPS secretion and surface hydrophobicity. Routine wastewater parameters in the continuous flow system were measured every three days. Sampling was performed after the mixed liquor from the aerobic tank was removed and centrifuged for 5 minutes. The supernatant was used to measure effluent quality indicators. Indicators such as DO and pH were determined using national standard methods.

[0075] The results of the control test are as follows:

[0076] 1. Changes in morphology and structure

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] Aerobic granular sludge appeared in the R5 group reactor on the 9th day, and the granules matured on the 25th to 29th 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] Aerobic granular sludge with loose particle structure appeared in the R12 group reactor on the 40th day.

[0089] No granular sludge was produced in the R13 group reactor, and the sludge was in the form of flocs.

[0090] Aerobic granular sludge with loose particle structure appeared in the R14 group reactor on the 45th day.

[0091] No granular sludge was produced in the R0 group reactor, and the sludge was in the form of flocs.

[0092] 2. Changes in Sedimentation Performance

[0093] 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;

[0094] The sludge index in the R12 group reactor was 60–90 mL / g;

[0095] The sludge index of flocculent sludge in the R13 group reactor was 80~120mL / g;

[0096] The sludge index of flocculent sludge in the R14 group reactor was 70~100mL / g;

[0097] The sludge index of flocculent sludge in the R0 group reactor is 80~120mL / g.

[0098] The test results show that the aerobic granular sludge settling performance is good when powdered sludge carbon is added to the continuous flow reactor.

[0099] 3. Changes in chemical properties

[0100] After granular sludge maturation, the COD, TN, and TP removal rates were all optimal in the R1 group reactor. The peak COD, TN, and TP removal rates in the R1 group reactor were 91%, 82%, and 82%, respectively. The peak COD, TN, and TP removal rates in the R2 group reactor were 85%, 80%, and 75%, respectively. The peak COD, TN, and TP removal rates in the R3 group reactor were 86%, 82%, and 80%, respectively. The peak COD, TN, and TP removal rates in the R4 group reactor were 80%, 75%, and 78%, respectively. The peak COD, TN, and TP removal rates in the R5 group reactor were 80%, 70%, and 72%, respectively. The peak COD, TN, and TP removal rates in the R6 group reactor were 80%, 78%, and 70%, respectively. The peak COD, TN, and TP removal rates in the R7 group reactor were 85%, 74%, and 72%, respectively. The COD, TN, and TP removal rates at the peak points of the R8 group reactor were 80%, 77%, and 70%, respectively. The COD, TN, and TP removal rates at the peak points of the R9 group reactor were 80%, 74%, and 73%, respectively. The COD, TN, and TP removal rates at the peak points of the R10 group reactor were 82%, 76%, and 70%, respectively. The COD, TN, and TP removal rates at the peak points of the R11 group reactor were 85%, 77%, and 75%, respectively. The COD, TN, and TP removal rates at the peak points of the R12 group reactor were 72%, 66%, and 60%, respectively. The COD, TN, and TP removal rates at the peak points of the R13 group reactor were 60%, 60%, and 58%, respectively. The COD, TN, and TP removal rates at the peak points of the R14 group reactor were 75%, 65%, and 55%, respectively. The COD, TN, and TP removal rates at the peak points of the R15 group reactor were 65%, 60%, and 55%, respectively.

[0101] The continuous flow reactor involved in this embodiment is A 2 / O reactor, specific operating parameters: reactor dimensions are 51×6×25 cm in length×width×height, the sedimentation tank height-to-diameter ratio is 4:1, and the total effective volume is 7.6 L.

[0102] Through the above control test results, the following conclusions can be drawn:

[0103] The adsorption and conductivity of the calcium-phosphate-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 calcium-phosphate-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 calcium-phosphate-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 formed by the prepared calcium-phosphate-based sludge carbon powder has a shortened cultivation time, and the aerobic granular sludge system saves aeration volume and floor space compared with the conventional process, and can save energy consumption by 20 to 30%.

[0104] 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 analyzer. 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 the 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 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 sedimentation performance of sludge, among which SVI 10 Increased by 13.09 mL / g.

[0105] 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 continuous-flow aerobic granular sludge formation speed is significantly increased. Compared with the two methods of adding phosphate-calcium-based sludge carbon powder and not adding carbon powder, the present invention shortens the formation time by 40-70%. The aerobic granular sludge obtained by the present invention has excellent stability after maturity and can withstand large shock loads. It can treat sewage water quality that meets Class A standards and improves the treatment capacity for conventional pollutants by 10-30%. Compared with conventional aerobic granular sludge technology, it saves aeration volume and space, and saves energy consumption by 20-30%.

[0106] 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 variations or modifications within the scope of the claims, which do 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 by: 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 the mixture is uniformly stirred 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 concentration of the phosphoric acid 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: The hydrothermal reaction was carried out at 55-65°C in a hydrothermal reactor.

7. A phosphate-calcium-based sludge carbon for continuous flow aerobic granular sludge in situ cultivation, characterized by: Prepared according to any one of claims 1 to 6.

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