Method for culturing sludge with environment-resistant characteristic and application thereof

Abstract

The invention belongs to the technical field of sewage treatment, and discloses a method for culturing sludge with environmental resistance and application of the method. The culture method comprises the following steps: a static culture process: adding dry sludge into a first aerobic tank, closing water inlet and reflux for primary stuffy aeration, and adding environment-resistant characteristic bacteria for secondary stuffy aeration after the dry sludge is converted into flocculent sludge; the dynamic culture process comprises the following steps: adding dry sludge into a second aerobic tank, controlling the water inflow, and adding environmental characteristic bacteria after the dry sludge is converted into flocculent sludge; and a mixed culture process, wherein the mixed culture process comprises the step of inoculating the sludge obtained in the static culture process into the sludge obtained in the dynamic culture process. The activated sludge obtained by the sludge culture method disclosed by the invention shows a better wastewater treatment effect in a two-stage A / O (Anoxic / Oxic) treatment process.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method for cultivating environmentally resistant sludge and its application. Background Technology

[0002] In recent years, livestock and poultry farming pollution has become the third largest source of pollution after industrial and domestic pollution, and one of the main causes of agricultural non-point source pollution in my country. High-concentration wastewater discharged into rivers and lakes causes continuous deterioration of surface water and groundwater quality, resulting in serious environmental pollution, directly endangering human health, and severely restricting the development of the livestock industry. The treatment of livestock and poultry farming wastewater has now attracted great attention from farm owners and relevant departments, and it is imperative to take a series of prevention and control measures and select economical and efficient treatment technologies.

[0003] The activated sludge process is currently the most widely used wastewater treatment method, with advantages such as simplicity and high efficiency. However, it also generally suffers from problems such as large land area requirements, excessive residual sludge, high costs, and a tendency for sludge bulking. Moreover, traditional activated sludge cultivation methods cannot achieve satisfactory treatment results for wastewater in special environments, such as high salinity and high temperature conditions. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for cultivating environmentally resistant activated sludge and its application. By using a staged cultivation method to cultivate environmentally resistant activated sludge, the problem of poor treatment effect of ordinary activated sludge on pig farm wastewater with high salinity and other conditions is solved.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] This invention provides a method for cultivating environmentally resistant sludge, comprising:

[0007] The static culture process is as follows: dry sludge is added to the first aerobic tank and the inlet and outlet are closed for initial aeration. After the dry sludge is converted into flocculent sludge, environmentally tolerant bacteria are added for secondary aeration.

[0008] The dynamic cultivation process is as follows: dry sludge is added to the second aerobic tank and the influent flow is controlled. After the dry sludge is converted into flocculent sludge, environmental characteristic bacteria are added.

[0009] The mixed culture process is as follows: the sludge obtained from the static culture process is inoculated into the sludge obtained from the dynamic culture process.

[0010] In some embodiments, during the static culture process, the amount of dry sludge added is 3%-6% of the influent volume, and during the initial aeration period, carbon source and alkalinity are supplemented based on SV30, pH, ammonia nitrogen and COD data.

[0011] In some embodiments, during the static culture process, the environmentally tolerant bacteria are salt-tolerant bacteria, and the amount of these bacteria added is 0.4%-0.8% of the influent volume; the pH during the re-aeration period is 7-7.5; and the re-aeration continues until the COD degradation rate is not less than 45% and NH4+ is reduced. + -N decreased by more than 60%.

[0012] In some embodiments, during the dynamic cultivation process, the amount of dry sludge added is 3%-6% of the influent volume, and the influent volume for dynamic cultivation is 30%-50% of the influent volume during normal system operation.

[0013] In some embodiments, during dynamic culture, the environmentally tolerant bacteria are salt-tolerant bacteria, the daily addition amount of the environmentally tolerant bacteria is 0.08%-0.15% of the influent water volume, and the addition time of the salt-tolerant bacteria is 6-8 days.

[0014] In some embodiments, during the mixed culture process, the inoculation process is as follows: after the static culture process is completed, water is introduced into its biological tank so that the sludge in the biological tank of the static culture process flows to the biological tank of the dynamic culture process, and finally flows to the shared sedimentation tank. The sludge in the shared sedimentation tank is then returned to the biological tank of the static culture process, gradually achieving mixing.

[0015] Furthermore, the influent volume in the biochemical tank during the static culture process is 10%-20% of the influent volume during normal system operation; the total influent volume of the system is controlled at 200m³. 3 Within / d; the water inflow rate of the biochemical tank in the static culture process is less than the water inflow rate of the biochemical tank in the dynamic culture process.

[0016] Furthermore, the culture is carried out continuously and stably for ≥72 hours, with an effluent COD removal rate ≥85% and NH4+ removal rate ≥95%. + -N removal rate ≥80%, and simultaneously meets SVI 60-120mL / g and SOUR ≥10mg O2·gMLSS -1 ·h -1 When the salt-tolerant sludge has been cultured, it can be determined that it is ready for use.

[0017] In some embodiments, carbon sources and / or trace elements and / or alkalinity are supplemented during the static culture process; and / or

[0018] Supplementing carbon sources and / or trace elements and / or alkalinity during the dynamic culture process; and / or

[0019] During the mixed culture process, carbon sources and / or trace elements and / or alkalinity are supplemented.

[0020] The present invention also provides an application of activated sludge cultured according to the above-described culture method in a two-stage A / O treatment process.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] This invention employs a phased cultivation method, which, compared to the traditional one-time cultivation method, allows for precise control of the sludge's gradual adaptation to a favorable environment and enhances its treatment capacity. Furthermore, during the dynamic cultivation phase, by controlling the influent flow, supplementing the carbon source, and gradually increasing the amount of environmentally tolerant bacteria, the biological activity of the sludge and the system load can be flexibly adjusted to cope with different load changes during wastewater treatment. In the mixed cultivation phase, sludge from the static cultivation group can be inoculated into the dynamic cultivation group to enhance its nitrification capacity. Through this synergistic effect, sludge from different cultivation methods can complement and enhance each other, resulting in stronger treatment capacity. In addition, the two systems share a single sedimentation tank, reducing facility complexity and operating costs, while improving the efficiency of the sedimentation tank through sludge mixing and cultivation.

[0023] The activated sludge obtained by the cultivation method of the present invention can achieve the effluent quality of high-salt wastewater such as pig farm wastewater reaching the standard of agricultural irrigation water in a two-stage A / O treatment process. Detailed Implementation

[0024] The present invention will be further described in detail with reference to specific embodiments. The following embodiments can enable those skilled in the art to have a more comprehensive understanding of the present invention, but do not limit the present invention in any way.

[0025] Those skilled in the art will understand that the order in which the steps are written in the various implementations or embodiments does not imply a strict execution order and does not constitute any limitation on the implementation process. The detailed execution order of each step should be determined by its function and possible internal logic. Unless otherwise specified, all steps in this application can be performed sequentially or randomly, preferably sequentially. For example, if the method includes steps 1 and 2, it means that the method may include steps 1 and 2 performed sequentially, or it may include steps 2 and 1 performed sequentially. For example, if the method may also include step 3, it means that step 3 can be added to the method in any order. For example, the method may include steps 1, 2, and 3, or it may include steps 1, 3, and 2, or it may include steps 3, 1, and 2, etc.

[0026] Example 1:

[0027] This embodiment provides a method for cultivating environmentally resistant sludge, specifically including the following process:

[0028] 1. Equipment and raw materials: Two sets of A / O systems in series, each system consisting of one anoxic tank and one aerobic tank, with a volume of 300m³ for each biological tank. 3 The wastewater originates from pig farming wastewater, and its quality is as follows: CODcr 5208 mg / L, NH4+ + -N524mg / L, TP 49.7mg / L, pH 7.1, SS 881mg / L.

[0029] 2. Static culture process (Day 0)

[0030] Sludge addition: 10t of dry sludge is added to the aerobic tank (first aerobic tank) of the A / O system in the static culture process to facilitate the formation of highly active nitrifying bacteria flocs locally. After sludge addition, the inlet and return valves of the static culture system are closed to isolate the fluid, and only stirring / aeration is maintained at a minimum to avoid strong shear.

[0031] Aeration / Closed Cultivation: After adding sludge, aerate for 24-48 hours (i.e., stop external wastewater intake and reflux, only maintain suspension with low-speed stirring), and measure SV30, pH, and NH4 daily during this period. + -N, COD.

[0032] Control parameters: Dissolved oxygen (aerobic zone) should be maintained at 2.0-3.0 mg / L (or intermittent aeration can be used to maintain the oxidation state depending on the equipment), and pH should be controlled at 7.0-7.5. If the pH drops or the alkalinity is insufficient, alkalinity regulators (NaHCO3 or Na2CO3) should be added in several batches to ensure nitrification activity; carbon supplementation (sodium acetate) should be used to adjust carboxyl energy to promote biofilm formation and adjust the COD in the tank to 150-250 mg / L.

[0033] Indicator determination: After 7-10 days of sludge aeration, if the COD degradation rate reaches 45%-55% and the SV30 / settling ratio shows sludge flocculation (flocs are visible and the settling speed is significantly improved), then the inoculum addition stage can begin.

[0034] Salt-tolerant bacteria addition: Add 150 kg of salt-tolerant bacteria to the first aerobic tank. After addition, continue aeration and monitor daily. Adjust alkalinity when pH < 6.8 or daily decrease > 0.2, and supplement carbon source when SVI > 120 mL / g.

[0035] Key criteria: SV30, pH, NH4 + Based on four parameters—NH4+, COD, and pH—the "static switching conditions" are met when the moving average fluctuation of the three parameters within 24 hours is no greater than ±5% and the pH is between 6.8 and 7.2. This indicates that the static culture system has been established. Specifically, the COD degradation rate must be ≥45% and the NH4+ level must be within a certain range. + -N decreases by more than 60%; if NH4 +If -N does not decrease or pH remains below 6.8, alkalinity should be increased and dissolved oxygen and temperature should be checked.

[0036] 3. Dynamic culture process (Day 0) (conducted simultaneously with the static culture process)

[0037] Sludge addition: 10t of dry sludge is added to the aerobic tank (second aerobic tank) of the A / O system in the dynamic cultivation process.

[0038] Start-up culture: Introduce conventional low-flow-rate water into the biochemical tank of the dynamic culture system (influent flow rate reduced to 30%-50% of the design flow rate, design flow rate is 400 m³). 3 / d) to promote a dynamic culture environment of "gradual increase in sludge and formation of bacterial flocs"; and a small amount of carbon source (sodium acetate) is added at the inlet of the anoxic zone to maintain COD at 150-250 mg / L.

[0039] Salt-tolerant bacteria addition: 25 kg of salt-tolerant bacteria were added to the aerobic tank daily for 7 consecutive days; at the same time, the COD and NH4 content of the effluent from this group were monitored daily. + -N, if pH or NH4 is present + -N rises sharply, so adjust the dosage and water intake in time.

[0040] Operational control: Maintain DO at 2-3 mg / L in the aerobic zone, 0.5-1 mg / L in the facultative anaerobic zone, and <0.2 mg / L in the anaerobic zone; maintain the C / N ratio and trace elements (Fe, Ni, Co, etc.) to meet the subsequent needs of nitration / methanogenesis.

[0041] 4. Mixed culture and system recovery water intake (Day 8-28)

[0042] Mixed culture process: When the static culture system is established (aerobic tank NH4) + -N decreased significantly, SVI / floc remained stable. Gradually turn on the influent to the static culture system (initially at 10%-20% of the daily influent volume), and allow the two systems to gradually mix through sludge return from the shared sedimentation tank, thereby "inoculating" the adaptive nitrifying sludge from the static culture system into the dynamic culture system.

[0043] Water inlet steps: Total water inflow controlled ≤200m³ 3 / d (for trial operation), initial allocation of 50m static group 3 / d、Dynamic Group 100m 3 / d, and then gradually scale up the scale (increasing by 20% each step) according to system stability and effluent indicators until it is consistent with the wastewater treatment process.

[0044] Nutritional replenishment: Due to the reduced influent volume, to prevent sludge deflocculation caused by insufficient nutrients, carbon source is supplemented according to the daily COD requirement of 150-250 mg / L, and trace elements and alkalinity are also supplemented.

[0045] Judgment: When the effluent from both systems A / O is stable and the sludge returned from the sedimentation tank contains good flocs (SV30 / sedimentation ratio meets process requirements), normal influent can be gradually restored and the system can enter normal operation / subsequent processes (sedimentation, disinfection, etc.); if SVI ≤ 150 mL / g or the sedimentation ratio is significantly improved, it indicates that the sludge flocs are qualified; if the flocs are loose, the organic load of the influent should be appropriately increased or the shearing should be reduced and a floc-forming agent (trace amount of organic colloid) should be added.

[0046] Example 2:

[0047] This embodiment provides an application of salt-tolerant sludge cultured according to the cultivation method described in Example 1 in a two-stage A / O treatment process. The treated wastewater quality is: CODcr 5208 mg / L, NH4+ + -N 524 mg / L, TP 49.7 mg / L, pH 7.1, SS 881 mg / L, treatment scale 400 m³ / L 3 / d.

[0048] The process is as follows: equalization tank homogenization → primary A / O → secondary A / O → secondary sedimentation tank reflux.

[0049] Operating pH 6.8-7.5; controlling DO 1.5-2.5 mg / L in the aerobic zone; stirring in the anoxic zone, with ORP approximately -50 to +50 mV; adding salt-tolerant sludge from Example 1, initial MLSS 4-6 g / L; sludge return ratio 50%-75%, nitrification liquor return ratio 150%-250%; SRT (aerobic meter) ≥ 25 days. If alkalinity is insufficient, supplement with NaHCO3 / Na2CO3 (mixed liquor alkalinity ≥ 150-300 mg / L); when denitrification is required, pulse supplement with a small amount of readily degradable carbon source.

[0050] Phase 1 (Start-up): Total water intake ≤ 200m 3 / d Continuous operation for 2-3 days. Criteria: Enter stage 2 after the three-day moving average meets the following conditions: COD removal rate ≥80% and SVI 60-120mL / g; if any indicator fluctuates >10%, revert and stabilize for 48 hours before reassessing.

[0051] Phase 2 (Transitional Release): Increase the total inflow to 300m³ 3 The system will operate continuously for 2-3 days to maintain the above-mentioned effluent and sludge indicators at compliance. Criterion: If the three-day moving average continues to meet the standards and the fluctuation is ≤±10%, proceed to stage 3; if not, revert to the previous step and stabilize for 48 hours.

[0052] Phase 3 (Full Load and Stabilization Period): Increase to design capacity of 400m 3 / d continuous operation. Criteria: If the COD removal rate is ≥80% (or the effluent COD reaches the target limit) for ≥72 hours, the SVI is 60-120mL / g and the pH is 6.8-7.5, it is considered to have entered the stable operation period; thereafter, it is maintained by conventional control (SRT, DO, alkalinity and necessary carbon source fine-tuning).

[0053] Comparative Example 1:

[0054] This comparative example provides a common activated sludge cultivation method, including:

[0055] 1. Equipment and raw materials: equalization tank, two-stage A / O system, secondary sedimentation tank; wastewater originates from pig farming wastewater, with wastewater quality as follows: CODcr 5208 mg / L, NH4+ + -N 524mg / L, TP 49.7mg / L, pH 7.1, SS 881mg / L.

[0056] 2. Activated sludge cultivation:

[0057] The dry sludge used and its quality were consistent with those in Example 1, and the sludge was added to the aerobic zone. Batch washing combined with continuous influent mixing was adopted for startup, with a startup period of 7-14 days. During operation, the following parameters were maintained: aerobic zone DO: 2.0-3.5 mg / L; temperature 20-30℃; pH 6.8-7.5; internal reflux, with a reflux ratio of 100%-200% (adjusted according to nitrification requirements). During operation, trace elements (Fe, Mn) needed to be supplemented, and COD and NH4 needed to be measured daily. + -N, DO, pH, SV30 / SVI data, after 7-14 days, COD removal rate is not less than 70%, NH4 + The culture ends when -N decreases significantly, SVI reaches 80-150 mL / g, and sludge flocs are in good condition.

[0058] This comparative example also provides the application of activated sludge cultured according to the method of this comparative example in a two-stage A / O treatment process. The treatment method is the same as in Example 2.

[0059] Comparative Example 2:

[0060] This comparative example provides a conventional method for cultivating salt-tolerant sludge, including:

[0061] 1. Equipment and raw materials: equalization tank, two-stage A / O system, secondary sedimentation tank; wastewater originates from pig farming wastewater, with wastewater quality as follows: CODcr 5208 mg / L, NH4+ + -N 524mg / L, TP 49.7mg / L, pH 7.1, SS 881mg / L.

[0062] 2. Activated sludge cultivation:

[0063] The dry sludge used and its quality were the same as in Example 1, and the sludge was added to the aerobic zone. Salt-tolerant bacterial communities were formed in the treatment of wastewater subjected to high salt or intermittent high salt shocks using a method of gradual salt stress and selective acclimatization.

[0064] Initial stage (Day 0-7): Stabilize the sludge under low-salt conditions (equivalent NaCl 2-3g / L), perform conventional aeration, and maintain COD at 150-300mg / L. The operating parameters are: DO in the aerobic zone: 2.0-3.0mg / L; pH 7.0-7.5; temperature 25-35℃.

[0065] Incremental salting phase (salt increase every 3-5 days): Increase salt concentration by 2-5 g / L per step until the target operating salinity (30-50 g / L or site requirements) or microbial community stability is achieved (if floc disintegration occurs during the gradual adaptation process, appropriately reduce the salting step or supplement with organic polymerizers / exogenous carbon sources to restore flocs; if necessary, revert to a low-salt buffer phase). Operating parameters are: aerobic zone DO: 2.0-3.0 mg / L; pH 7.0-7.5; temperature 25-35℃. Daily monitoring of salinity (conductivity), COD, and NH4 is required. + If, under target salinity, COD removal rate can be stably maintained at no less than 40%-55%, SVI does not increase significantly, and floc morphology remains stable, then salt tolerance is considered successful. This is achieved through microscopic observation of N, pH, SV30, and bacterial flora.

[0066] The entire acclimatization period for this method is 4-8 weeks.

[0067] This comparative example also provides the application of activated sludge cultured according to the method of this comparative example in a two-stage A / O treatment process. The treatment method is the same as in Example 2.

[0068] The sludge cultured in Example 1 and Comparative Examples 1 and 2 was used to treat aquaculture wastewater (CODcr 5208 mg / L, NH4+). + The treatment of activated sludge (N 524 mg / L, TP 49.7 mg / L, pH 7.1, SS 881 mg / L) yielded the following results, as shown in the table below. The table shows that the salt-tolerant sludge obtained using the activated sludge cultivation method of this invention not only has higher COD, ammonia nitrogen, and total phosphorus removal rates than ordinary activated sludge, but also exhibits better wastewater treatment performance than conventional salt-tolerant sludge. Furthermore, compared to the activated sludge cultivation method of this invention, the traditional stepwise stress method takes longer (weeks to months) and requires strict gradient control; it also has lower treatment efficiency under high-salt conditions; it easily leads to the accumulation of high nucleic acid / low degradable matter; and it results in a loss of downstream anaerobic or nitrification capacity.

[0069] Table of Aquaculture Wastewater Treatment Performance of Various Activated Sludge Formations

[0070]

[0071] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A method for cultivating environmentally tolerant sludge, characterized in that, include: The static culture process is as follows: dry sludge is added to the first aerobic tank and the inlet and outlet are closed for initial aeration. After the dry sludge is converted into flocculent sludge, environmentally tolerant bacteria are added for secondary aeration. The dynamic cultivation process is as follows: dry sludge is added to the second aerobic tank and the influent flow is controlled. After the dry sludge is converted into flocculent sludge, environmental characteristic bacteria are added. The mixed culture process is as follows: the sludge obtained from the static culture process is inoculated into the sludge obtained from the dynamic culture process.

2. The cultivation method according to claim 1, characterized in that, During the static culture process, the amount of dry sludge added is 3%-6% of the influent volume, and during the initial aeration period, carbon source and alkalinity are supplemented according to SV30, pH, ammonia nitrogen and COD data.

3. The cultivation method according to claim 1, characterized in that, During static culture, the environmentally tolerant bacteria are salt-tolerant bacteria, and the addition amount of the environmentally tolerant bacteria is 0.4%-0.8% of the influent volume; the pH during the re-aeration period is 7-7.5; the re-aeration continues until the COD degradation rate is not less than 45% and NH4+ is reduced. + -N decreased by more than 60%.

4. The cultivation method according to claim 1, characterized in that, During the dynamic cultivation process, the amount of dry sludge added is 3%-6% of the influent volume, and the influent volume for dynamic cultivation is 30%-50% of the influent volume during normal system operation.

5. The cultivation method according to claim 1, characterized in that, During the dynamic culture process, the environmentally tolerant bacteria are salt-tolerant bacteria, and the daily addition amount of the environmentally tolerant bacteria is 0.08%-0.15% of the influent water volume, and the addition time of the salt-tolerant bacteria is 6-8 days.

6. The cultivation method according to claim 1, characterized in that, During the mixed culture process, the inoculation process is as follows: after the static culture process is completed, water is introduced into its biological tank so that the sludge in the biological tank of the static culture process flows to the biological tank of the dynamic culture process, and finally flows to the shared sedimentation tank. The sludge in the shared sedimentation tank is then returned to the biological tank of the static culture process, gradually achieving mixing.

7. The cultivation method according to claim 6, characterized in that, The water inflow to the biochemical tank during the static culture process is 10%-20% of the water inflow during normal system operation; the total water inflow to the system is controlled at 200m³. 3 Within / d; the water inflow rate of the biochemical tank in the static culture process is less than the water inflow rate of the biochemical tank in the dynamic culture process.

8. The cultivation method according to claim 6, characterized in that, The culture is carried out continuously and stably for ≥72 hours, and the effluent COD removal rate is ≥85%, NH4+ removal rate is ≥90%. + -N removal rate ≥80%, and simultaneously meets SVI 60-120mL / g and SOUR ≥10mg O2·gMLSS -1 ·h -1 When the salt-tolerant sludge has been cultured, it can be determined that it is ready for use.

9. The cultivation method according to claim 1, characterized in that, Supplementing carbon sources and / or trace elements and / or alkalinity during the static culture process; and / or Supplementing carbon sources and / or trace elements and / or alkalinity during the dynamic culture process; and / or During the mixed culture process, carbon sources and / or trace elements and / or alkalinity are supplemented.

10. The application of activated sludge cultured by the cultivation method according to any one of claims 1-9 in a two-stage A / O treatment process.

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