A low-carbon source water under rich in internal carbon source denitrification functional bacteria sludge domestication device, method and application

Abstract

The application belongs to the technical field of environmental governance, and particularly relates to a low-carbon-source-influent under-enriched-internal-carbon-source denitrification functional bacteria sludge domestication device, method and application. The device comprises a main-stream anaerobic tank, a main-stream aerobic tank and a secondary sedimentation tank connected in sequence along the sewage flow direction, the aerobic tank is connected with a side-stream anaerobic reactor, the side-stream anaerobic reactor is connected with the water inlet end and the water outlet end of the aerobic tank, the side wall of the secondary sedimentation tank is provided with a water outlet, and the bottom of the secondary sedimentation tank is connected with the bottom of the anaerobic tank. The device has simple process layout, small reconstruction land area and energy saving. When the device is used for microbial enrichment and simultaneous sludge reduction under low-carbon-source-influent, by fully utilizing the reducing power required by the side-stream anaerobic reactor backflow sludge, competition of aerobic heterotrophic microorganisms for dissolved oxygen and carbon source can be avoided, DPAO or DGAO is enriched, and finally the enrichment of low-carbon-source microorganisms and sludge reduction are realized, and the simultaneous denitrification effect is better.

Description

Technical Field

[0001] This invention belongs to the field of environmental governance technology, specifically relating to a device, method, and application for acclimating denitrifying functional bacteria in mud with low carbon source influent and rich in internal carbon source. Background Technology

[0002] Urban sewage exhibits varying water quality characteristics across different cities and at different times. Furthermore, rising urbanization levels and improved living standards have led to increased daily water consumption. Coupled with lagging urban pipe network construction that cannot keep pace with the development of sewage treatment plants, carbon source scarcity has become a major challenge for sewage treatment plants, resulting in insufficient nitrogen and phosphorus removal. Currently, the cost of treating and disposing of excess sludge is high, accounting for approximately 20%-45% of the operating costs of sewage treatment plants. Therefore, it is necessary to develop lower-cost sludge treatment processes.

[0003] In-situ sludge reduction is a wastewater treatment technology that, while ensuring effluent quality, employs appropriate physical, chemical, and biological measures to allocate more energy to maintaining sludge metabolism rather than promoting its growth. This in-situ sludge reduction technology aligns with the goals of carbon reduction and neutralization. Denitrifying phosphorus-removing bacteria (DPAOs) and denitrifying polysaccharide bacteria (DGAOs) are important species for enhancing nitrogen and phosphorus removal in low-carbon influent. Their growth requires less organic matter and dissolved oxygen (DO), saving >50% of aeration and reducing sludge production. They also possess higher resistance to shock loads, and their enrichment helps reduce the carbon footprint of wastewater treatment processes adhering to energy conservation and emission reduction principles. In the anaerobic stage, DPAOs can absorb VFAs through active transport and ultimately store them in the cell as PHAs. This process is driven by intracellular polyphosphate hydrolysis and glycogenolysis. In the anoxic stage, DPAOs can further reduce nitrogen and phosphorus content by converting DPAOs into nitrogen dioxide (NO3). 3- -N / NO 2- -N acts as an electron acceptor, breaking down intracellular carbon source PHA. Part of the energy generated is used for microbial growth and glycogen synthesis, while the remainder is used to over-absorb phosphate ions from the environment, storing them within the cell as polyphosphates. After the anoxic phase, a portion of the phosphorus-rich sludge is discharged, ultimately achieving phosphorus removal. Similar to DPAOs, DGAOs can convert VFAs into endogenous storage substances under anaerobic conditions, storing them intracellularly, and under anoxic conditions, converting them into NO. 3- -N / NO 2- -N acts as an electron acceptor, consuming intracellular stored substances and undergoing internal carbon source denitrification.

[0004] Simultaneous nitrification-denitrification phosphorus removal (SNDPR) is a "multi-purpose carbon" process. Its sludge is rich in DPAOs and DGAOs, and it operates primarily in a batch mode, alternating between anaerobic and aerobic processes. However, it suffers from challenges in controlling treatment parameters, such as dissolved oxygen (DO) concentration. Higher DO concentrations promote aerobic heterotrophic reactions and stimulate complete nitrification, rather than promoting the growth of denitrifying DPAOs and DGAOs. Therefore, excessively high DO concentrations can lead to incomplete denitrification and elevated nitrogen (N) concentrations in the effluent. Conversely, excessively low DO concentrations result in incomplete nitrification, affecting denitrification efficiency. Although the lower electron transport rate of internal carbon source denitrifying bacteria is beneficial for reducing their growth, the contribution of DPAO and DGAO enrichment to in-situ sludge reduction has not been thoroughly investigated. Therefore, there is an urgent need to develop a sludge acclimation device and method for denitrifying functional bacteria rich in internal carbon sources under low carbon source influent, and its application in sludge reduction, so as to improve the abundance of denitrifying functional bacteria rich in internal carbon sources in sludge, thereby addressing the challenges of limited nitrogen and phosphorus removal capacity and insufficient sludge reduction potential under low carbon source influent. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention proposes a sludge acclimation device for denitrifying functional bacteria with low carbon source influent and rich in internal carbon source. This device is applied to the reduction of sludge in urban domestic sewage. By making full use of the reducing power required for the sludge returned from the side-flow anaerobic reactor, it can avoid the competition of aerobic heterotrophic microorganisms for dissolved oxygen and carbon source, thereby enriching DPAO or DGAO, and finally achieving the enrichment of low carbon source microorganisms and sludge reduction, with better simultaneous denitrification effect.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] The first aspect of this invention provides a sludge acclimation device for denitrifying functional bacteria with a low-carbon-source influent and rich in internal carbon sources. The device includes a main anaerobic tank, a main aerobic tank, and a secondary sedimentation tank connected sequentially along the wastewater flow direction. The aerobic tank is connected to a side-flow anaerobic reactor, which is connected to both the inlet and outlet of the aerobic tank. The secondary sedimentation tank has an outlet on its sidewall, and its bottom is connected to the bottom of the anaerobic tank. The sludge inlet of the side-flow anaerobic reactor is connected to the aerobic tank for facilitating sludge treatment, and the sludge outlet of the side-flow anaerobic reactor is also connected to the aerobic tank for facilitating sludge removal.

[0008] Preferably, the device further includes a mainstream anoxic tank, which is located between the anaerobic tank and the aerobic tank, and is also connected to the effluent end of the aerobic tank.

[0009] Preferably, the side-flow anaerobic reactor is a pulse-aeration anaerobic reactor, which includes a stirring mechanism and an aeration device. The stirring mechanism is located on the inner top wall of the side-flow anaerobic reactor, and the aeration device is located on the inner bottom wall. The stirring mechanism is used to stir the lower layer of sludge-water mixture and the supernatant in the side-flow anaerobic reactor to form a sludge-water mixture for sludge discharge, or to stir the lower layer of sludge-water mixture and the supernatant for homogenization.

[0010] Preferably, the lateral flow anaerobic reactor uses a first drive pump and a second drive pump to feed and discharge sludge.

[0011] The second aspect of this invention also provides the application of the denitrification functional bacteria sludge acclimation device with low carbon source influent and rich in internal carbon source described in the first aspect in the reduction of sludge in urban domestic sewage.

[0012] The third aspect of this invention also provides a method for simultaneous sludge reduction through microbial enrichment under low-carbon source influent. This method utilizes the sludge acclimation device for denitrifying bacteria rich in internal carbon sources under low-carbon source influent as described in the first aspect to treat low-carbon source wastewater: the wastewater enters an anaerobic tank and is further treated through an aerobic tank or an anoxic tank and an aerobic tank. The sludge-water mixture at the end of the aerobic tank enters a secondary sedimentation tank, or, at a ratio of 3:1, part of it is returned to the anoxic tank and part enters the secondary sedimentation tank. After sludge-water separation in the secondary sedimentation tank, the effluent is discharged. In this stage, only 95% of the sludge-water mixture enters the secondary sedimentation tank or is returned to the anoxic tank, while the remaining 5% is returned to the side-flow anaerobic reactor. The sludge after anaerobic treatment in the side-flow anaerobic reactor flows back into the aerobic tank for further aerobic treatment. The underflow from the secondary sedimentation tank can be fed back to the input end of the anaerobic tank, and the underflow can also be the output of the secondary sedimentation tank.

[0013] The specific operation of the above process includes the following steps:

[0014] S1: Preprocessing:

[0015] Selecting suitable influent water quality ensures its low carbon source characteristics, with influent COD at 150-180 mg / L, NH4+-N at 10-40 mg / L, and TP at 1-4 mg / L. Low organic matter content in the water source reduces carbon input during subsequent treatment. Regular monitoring of water quality indicators, such as chemical oxygen demand (COD), influent nitrogen (NH4+ and TN), influent phosphorus (TP), suspended solids (SS), nutrients, and heavy metals, helps determine water quality suitability, facilitates the selection of suitable sources for subsequent treatment, and allows for necessary physical and chemical pretreatment to remove larger particles, improve water quality, and prevent negative impacts on subsequent treatment processes.

[0016] S2: Mainstream regulation of the anaerobic / aerobic ratio and selection of appropriate microbial populations:

[0017] In a low-carbon-source environment, the anaerobic and aerobic tanks of the mainstream biological selector combine wastewater and recycled biomass to promote internal carbon source conversion and the formation of a high electron acceptor gradient, creating substrate conditions for internal carbon source denitrification bacteria. The hydraulic retention time ratio between the anaerobic and aerobic tanks is ≥1, allowing for the screening of highly adaptable internal carbon source microorganisms to promote material cycling and energy flow, maintain ecological balance, and effectively degrade environmental pollutants and treat waste, thereby facilitating sludge separation and enrichment.

[0018] S3: Optimized mainstream operation adjustments:

[0019] By adjusting temperature, pH, and dissolved oxygen (DO), microorganisms are cultured at different temperatures, pH values, and residence times. The optimal temperature, pH, and residence time for microbial growth and reproduction are then selected, promoting the growth and reproduction of carbon-source microorganisms within the storage tank and regulating carbon source distribution. Since dissolved oxygen (DO) levels in water are affected by factors such as atmospheric oxygen, temperature, and humidity, rapid DO detection tools are typically used for monitoring. The monitored DO levels can be adjusted to regulate the downstream dissolved oxygen environment based on the effluent quality, enabling the removal of COD, N, and P downstream of the aerobic tank.

[0020] S4: Implement synchronous extraction: During the treatment process, the activated sludge enriched in the secondary sedimentation tank is extracted periodically for resource reuse or treatment and disposal, so that the enriched sludge is quickly separated and discharged from the system, thereby reducing the sludge retention time.

[0021] S5: Adjusting the Circulating System of the Side-Flow Anaerobic Reactor: Adjust the sludge retention time of the side-flow anaerobic reactor to 10-15 days, and its hydraulic retention time to 3-10 days. The daily sludge exchange rate is 10-15%, and the sludge circulation frequency of the side-flow anaerobic reactor is 4-6 times / day to ensure the abundance of DPAO and DGAO and the stability of the system. By adopting a circulating system, the microbial return ratio can be effectively improved, thereby increasing the concentration of microorganisms within the system, promoting the interaction between similar microorganisms, and improving the treatment effect. Furthermore, a sludge return pipeline containing the side-flow anaerobic reactor with a long sludge retention time (SRT > 5 days) is added to the aerobic tank of the traditional mainstream process. The phosphate and ammonia nitrogen released by the high concentration of biomass anaerobic digestion in the side-flow anaerobic reactor ensures the P and N sources for DPAO and DGAO, and the longer anoxic effect brought to the mainstream ensures the higher ecological niche of the internal carbon source denitrification functional bacteria. Meanwhile, the side-flow anaerobic reactor eliminates microorganisms that are not suitable for growth in alternating environments, and the latent growth brought about by their death achieves a reduction effect of up to 50%, further solidifying the dominant position of DPAO and DGAO.

[0022] S6: Sideflow Anaerobic Reactor Monitoring and Adjustment: Regularly monitor the operating status of the sideflow anaerobic reactor and the main biological selector, including changes in the concentration of organic matter in the wastewater, microbial activity, ORP, pH, DO, and effluent quality. Adjust the operating parameters of the sideflow anaerobic reactor in a timely manner to ensure the abundance of DPAO and DGAO and the stability of the system; for example, increase the first and second preset exchange frequencies of the sideflow anaerobic reactor, as well as the aeration frequency and duration of the sideflow anaerobic reactor.

[0023] Preferably, in S2, the hydraulic retention time of the anaerobic tank is adjusted to 2.7 h and the hydraulic retention time of the aerobic tank is adjusted to 2.3 h; or the hydraulic retention time of the anaerobic tank is adjusted to 2 h, the hydraulic retention time of the anoxic tank is adjusted to 2 h, and the hydraulic retention time of the aerobic tank is adjusted to 2 h.

[0024] Preferably, in S3, pH = 7.5, DO = 2-3 mg / L, and T = 25℃.

[0025] Preferably, in S5, after the sludge enters the side-flow anaerobic reactor, aeration is added once every 2-3 hours, and the aeration duration is 2 minutes.

[0026] Preferably, in S6, adjusting the operating parameters of the side-flow anaerobic reactor includes adjusting the first preset exchange frequency and the second preset exchange frequency of the side-flow anaerobic reactor, wherein both the first preset exchange frequency and the second preset exchange frequency of the side-flow anaerobic reactor are 4-6 times / day; the basis for adjusting the operating parameters of the side-flow anaerobic reactor includes a sludge concentration of 2500-3500 mg / L, pH = 7-7.5, DO change of 2-3 mg / L, and effluent quality of Class A standard.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] This invention discloses a sludge acclimation device for denitrifying functional bacteria rich in internal carbon sources under low-carbon source influent. The device includes a main anaerobic tank, a main aerobic tank, and a secondary sedimentation tank connected sequentially along the wastewater flow direction. The aerobic tank is connected to a side-flow anaerobic reactor, which is connected to the inlet and outlet of the aerobic tank. The secondary sedimentation tank has an outlet on its side wall, and its bottom is connected to the bottom of the anaerobic tank. This device has a simple process layout, requires less land area for modification, and saves energy. When used for microbial enrichment and simultaneous sludge reduction under low-carbon source influent, by fully utilizing the reducing power required for sludge return from the side-flow anaerobic reactor, it can avoid competition for dissolved oxygen and carbon sources by aerobic heterotrophic microorganisms, thereby enriching DPAO or DGAO, ultimately achieving the enrichment of low-carbon source microorganisms and sludge reduction, with better simultaneous denitrification effect. Overall, this invention has the following advantages:

[0029] (1) The microbial enrichment and simultaneous sludge reduction method under low carbon source influent provided by the present invention introduces a side-flow anaerobic reactor with a long sludge retention time (SRT>5 days) into the aerobic tank of the traditional activated sludge process through a sludge return pipeline. The sludge exchange rate is 10%-15% per day. When the anaerobic sludge is extremely starved, it is returned to the aerobic tank and competes for oxygen twice as much to restore its activity. The oxygen is kept at a low level (0.5mg / L-1mg / L), which is beneficial to enhance the competitiveness of DGAO and DPAO against nitrate nitrogen. At the same time, controlling the low aeration rate of the mainstream can maximize the formation of the acquired anoxic zone.

[0030] (2) The method for simultaneous sludge reduction with microbial enrichment under low carbon source influent provided by the present invention is that the phosphate released in the returned sludge is conducive to the absorption of DPAO into polyphosphate in the anoxic environment. At the same time, the long residence time created by the side-flow anaerobic reactor allows DGAO and DPAO with internal carbon sources to survive and carry out endogenous denitrification or phosphorus removal in the mainstream aerobic system, further expanding the competitive advantage. Moreover, the death of returned sludge in the side-flow anaerobic reactor increases under aerobic conditions, further promoting the latent growth of the mainstream system and improving the enrichment of specific microorganisms and the sludge reduction effect.

[0031] (3) The microbial enrichment and simultaneous sludge reduction method under low-carbon source influent provided by this invention can enrich endogenous denitrifying functional bacteria by adjusting the mainstream anaerobic / aerobic ratio, thereby improving the simultaneous nitrogen and phosphorus removal effect. At the same time, it can make full use of the reducing power required by the sludge returned from the side-flow anaerobic reactor, avoiding competition for DO by aerobic heterotrophic microorganisms, and thus enriching DPAO or DGAO. This process has a simple layout, requires less land area for modification, saves energy, and can achieve the enrichment of low-carbon source microorganisms and sludge reduction. Attached Figure Description

[0032] Figure 1 This refers to the A / O activated sludge treatment system of Example 1;

[0033] Figure 1 In the diagram, 110-anaerobic tank, 120-aerobic tank, 160-side-flow anaerobic reactor, 130-secondary sedimentation tank, 170-stirring mechanism, 165-aeration device, 105-sewage outlet, 125-sludge-water mixture pipeline, 145-sludge inlet pipeline, 150-first drive pump, 180-sludge outlet pipeline, 175-second drive pump, 135-output pipeline, 140-third drive pump, 190-water outlet.

[0034] Figure 2 The carbon source consumption and internal carbon source storage in anaerobic tank 110 are shown in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor in Example 1.

[0035] Figure 3The robust simulation results are for the control group (CK) and the experimental group (AS) with a side-flow anaerobic reactor in Example 1.

[0036] Figure 4 The dissolved oxygen changes in aerobic tank 120 in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor of Example 1 are shown.

[0037] Figure 5 The diagram shows the microbial abundance in aerobic tank 120 of the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor.

[0038] Figure 6 This refers to the A / O activated sludge treatment system of Example 2;

[0039] 210-Anaerobic tank, 220-Anoxic tank, 230-Aerobic tank, 280-Side flow anaerobic reactor, 250-Secondary sedimentation tank, 205-Sewage outlet, 240-Sludge-water mixture pipeline, 265-Sludge inlet pipeline, 270-First drive pump, 290-Sludge outlet pipeline, 285-Second drive pump, 255-Output pipeline, 260-Third drive pump, 295-Outlet, 235-Output pipeline, 245-Fourth drive pump.

[0040] Figure 7 The carbon source consumption and internal carbon source storage in the anaerobic tank 210, as well as the relative proportions of polyphosphate-accumulating bacteria (PAO) and polysaccharide-accumulating bacteria (GAO), were measured in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor in Example 2.

[0041] Figure 8 The non-endogenous denitrifying functional bacteria (Phase) in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor in Example 2. OL ) and endogenous denitrifying functional bacteria (Phase) AL The sludge reduction effect of enriched mainstream aerobic pond seed sludge. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described below. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0043] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods, and the experimental materials used in the following embodiments are all available through conventional commercial channels.

[0044] Example 1

[0045] Figure 1An example of an A / O activated sludge treatment system 100 is provided, namely a sludge acclimation device for denitrifying functional bacteria with low carbon source influent and rich internal carbon source. The device includes an anaerobic tank 110, an aerobic tank 120, and a secondary sedimentation tank 130 connected sequentially along the wastewater flow direction. The aerobic tank 120 is connected to a side-flow anaerobic reactor (pulse-aeration anaerobic reactor) 160. The side-flow anaerobic reactor 160 includes a stirring mechanism 170 (such as a stirring paddle) and an aeration device 165. The stirring mechanism 170 is disposed on the inner top wall of the side-flow anaerobic reactor 160 and is used to stir the lower layer of sludge-water mixture and the supernatant in the side-flow anaerobic reactor 160 to form a sludge-water mixture for sludge discharge, or to stir the lower layer of sludge-water mixture and the supernatant to make them homogeneous. The aeration device 165 is disposed on the inner bottom wall of the side-flow anaerobic reactor 160.

[0046] The anaerobic tank 110 is equipped with a wastewater outlet 105. The anaerobic tank 110 is connected to the aerobic tank 120. The aerobic tank 120 is connected to the sludge inlet pipe 145 through a sludge-water mixture pipeline 125. The other end of the sludge inlet pipe 145 is connected to the side-flow anaerobic reactor 160. A first drive pump 150 is also installed on the sludge inlet pipe 145. The side-flow anaerobic reactor 160 is connected to the aerobic tank 120 through a sludge outlet pipe 180 and a second drive pump 175. The aerobic tank 120 is also connected to the secondary sedimentation tank 130 through the sludge-water mixture pipeline 125. The bottom of the secondary sedimentation tank 130 is connected to the bottom of the anaerobic tank 110 through an outlet pipe 135. A third drive pump 140 is installed on the outlet pipe 135. An outlet 190 is also provided on the side wall of the secondary sedimentation tank 130.

[0047] Figure 1 The working principle of the device is as follows: Wastewater enters the anaerobic tank 110 from the wastewater outlet 105 and is further treated in the aerobic tank 120. The sludge-water mixture at the end of the aerobic tank enters the secondary sedimentation tank 130 through pipeline 125. After sludge-water separation in the secondary sedimentation tank 130, the effluent is discharged through the outlet 190. In this stage, only 95% of the sludge-water mixture enters the secondary sedimentation tank 130 through pipeline 125, while the remaining 5% flows back to the side-flow anaerobic reactor 160 through pipeline 125 along the sludge inlet pipe 145. The sludge after anaerobic treatment in the side-flow anaerobic reactor 160 flows back into the aerobic tank 120 through the sludge outlet pipe 180 for further aerobic treatment. The underflow from the secondary sedimentation tank 130 can be fed back to the input end of the anaerobic tank 110 through the output pipe 135. The underflow can also be the output of the secondary sedimentation tank 130 for further solids treatment, such as thickening, stabilization, conditioning, dewatering, sludge treatment, etc., as is known to those skilled in the art.

[0048] Will Figure 1 The specific implementation steps of the device shown in the diagram for sludge reduction are as follows:

[0049] S1: Preprocessing:

[0050] To demonstrate the acclimatization and enhancement effect of the side-flow anaerobic reactor 160, a device consisting of a main anaerobic tank 110, an aerobic tank 120, a secondary sedimentation tank 130, and corresponding supporting pipelines, including the side-flow anaerobic reactor 160, is described. Figure 1 The experimental group (AS) consisted of a main anaerobic tank 110 (excluding the side-flow anaerobic reactor 160), an aerobic tank 120, a secondary sedimentation tank 130, and corresponding pipelines, serving as the control group (CK). Both groups were equipped with identical wastewater to simulate the influent quality of urban domestic sewage, ensuring low carbon source characteristics (COD < 200 mg / L). The influent COD was 150-180 mg / L, and NH4+ was... + -N: 30-40mg / L, TP: 2-4mg / L.

[0051] S2: Adjusting the mainstream anaerobic / aerobic ratio and selecting suitable microbial populations:

[0052] The hydraulic retention time of the anaerobic tank 120 is adjusted to 2.7h, and the hydraulic retention time of the aerobic tank 120 is 2.3h. The extended retention time of the anaerobic tank is used to screen microorganisms with strong adaptability to store internal carbon sources, so as to promote material cycling and energy flow, maintain ecological balance, and enable them to effectively degrade environmental pollutants and promote the full treatment of waste, thereby facilitating the separation and enrichment of sludge.

[0053] S3: Optimized mainstream operation adjustments:

[0054] By adjusting the operating conditions such as temperature, pH, and DO in anaerobic tank 110 or aerobic tank 120, microorganisms were cultured at different temperatures, pH values, and residence times to select the optimal temperature for their growth and reproduction. The final screening results were: pH = 7.5, DO = 2-3 mg / L, T = 25℃.

[0055] S4: Implement synchronous extraction: During the treatment process, the activated sludge enriched in the secondary sedimentation tank 130 is periodically extracted for resource reuse or treatment and disposal, so that the enriched sludge is quickly separated and discharged from the system, thereby reducing the sludge retention time.

[0056] S5: Adjustment of the sludge circulation system in the side-flow anaerobic reactor 160: A side-flow anaerobic reactor 160 with a long sludge retention time (SRT = 10 days) is introduced into the aerobic tank 120. The hydraulic retention time is 3 days, the daily sludge exchange rate is 10%, and the sludge exchange frequency of the side-flow anaerobic reactor 160 is 4 times / day. That is, both the first and second preset exchange frequencies of the side-flow anaerobic reactor 160 are 4 times / day. This ensures the abundance of DPAO and DGAO and the stability of the system. By adopting the sludge circulation system of the side-flow anaerobic reactor 160, the dynamic balance of the sludge population can be effectively maintained. The long-term anaerobic starvation environment of the side-flow anaerobic reactor 160 can further screen out denitrifying phosphorus-removing bacteria (DPAO) and denitrifying polysaccharide bacteria (DGAO) with internal carbon source storage functions, and make them the dominant species. Furthermore, the high concentration of phosphates and ammonia nitrogen released from the biomass in the side-flow anaerobic reactor 160 ensures the P and N sources for DPAO and DGAO, and maintains a high ecological niche for the internal carbon source denitrifying bacteria through a prolonged anoxic effect. In addition, the side-flow anaerobic reactor 160 eliminates microorganisms unsuitable for growth in alternating environments, accelerating the death of mainstream microorganisms and their resulting latent growth.

[0057] S6: Monitoring and adjustment of the side-flow anaerobic reactor 160: Regularly monitor the operating status of the side-flow anaerobic reactor 160 and the main biological selector, and adjust the operating parameters of the side-flow anaerobic reactor 160 in a timely manner to ensure the stability of indicators such as sludge concentration (2500-3500mg / L), microbial activity, pH (7-7.5), DO change (2-3mg / L), and effluent quality (Grade A).

[0058] S7: Research and In-depth Study of Enriched Microorganisms: The carbon source consumption (difference in wastewater COD before and after entering the main anaerobic reactor) and the internal carbon source storage (difference between the COD value consumed by microorganisms and the COD value used for exogenous denitrification in the main anaerobic reactor) of the control group (CK) and the experimental group (AS) containing a 160-cell side-flow anaerobic reactor) were measured and calculated to verify the enrichment effect of DPAO and DGAO. Simultaneously, sludge was collected from the end of the aerobic tanks of CK and AS and stored at -80℃ for full-length 16S rRNA sequencing analysis to monitor changes in microbial abundance in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor, further investigating the specific species enriched with DPAO and DGAO. The 16S amplicon sequencing experimental procedure was performed according to the standard protocol provided by Illumina, including sample quality testing, library construction, library quality testing, and library sequencing.

[0059] Figure 2The carbon source consumption and internal carbon source storage in the anaerobic tank 110 were compared between the control group (CK) and the experimental group (AS) containing the side-flow anaerobic reactor 160. The internal carbon source conversion rate in AS (87%) was higher than that in CK (75%), indicating that after adding the side-flow anaerobic reactor 160, more of the carbon source consumed in the anaerobic tank was stored by microorganisms as internal carbon sources, indirectly reflecting the increased enrichment of internal carbon source bacteria.

[0060] Figure 3 The robustness simulation results for the control group (CK) and the experimental group (AS) with a side-flow anaerobic reactor demonstrate that AS exhibits higher stability and resistance to shock loads. Robustness represents the stability of the microbial network, and the simulation method uses the ASV table obtained from 16S sequencing to calculate the proportion of nodes remaining in the microbial network after a certain percentage of nodes are randomly removed. The higher the proportion of remaining nodes, the more stable the microbial community.

[0061] Figure 4 The dissolved oxygen levels in the aerobic tank 120 were compared between the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor. After aeration began, due to the return sludge from the side-flow anaerobic reactor 160 flowing back into the aerobic tank 120, unlike the gradual increase in dissolved oxygen in CK, the dissolved oxygen in AS remained below 1 mg / L for one hour, indicating an anoxic state. This state is conducive to the enrichment of denitrifying bacteria.

[0062] Figure 5 The top ten most abundant microbial species in the aerobic tank 120 of the control group (CK) and the experimental group (AS) containing the side-flow anaerobic reactor are shown. This indicates that after adding the side-flow anaerobic reactor 160, the low dissolved oxygen effect required by DPAO and DGAO can be brought about by the return sludge of the side-flow anaerobic reactor 160. Furthermore, the long-term anaerobic-aerobic alternating environment of the side-flow anaerobic reactor 160 can further screen out DPAO and DGAO with internal carbon sources, making them the dominant species and thus increasing the abundance of DGAO and DPAO.

[0063] Example 2

[0064] Based on the device in Example 1, an anoxic tank was added to construct a denitrifying functional microbial acclimatization device with low carbon source influent and rich internal carbon source, such as... Figure 6The A / O activated sludge treatment system 200 is shown. This device includes an anaerobic tank 210, an anoxic tank 220, an aerobic tank 230, and a secondary sedimentation tank 250 connected sequentially along the wastewater flow direction. The aerobic tank 230 is connected to a side-flow anaerobic reactor (pulse-aeration anaerobic reactor) 280. The side-flow anaerobic reactor 280 is also equipped with a stirring mechanism (such as a stirring paddle) and an aeration device. The stirring mechanism is located on the inner top wall of the side-flow anaerobic reactor 280 and is used to stir the lower layer of sludge-water mixture and the supernatant in the side-flow anaerobic reactor 280 to form a sludge-water mixture for sludge discharge, or to stir the lower layer of sludge-water mixture and the supernatant to make them uniform. The aeration device is located on the inner bottom wall of the side-flow anaerobic reactor 280.

[0065] The anaerobic tank 210 is equipped with a wastewater outlet 205. The anaerobic tank 210 is connected to the anoxic tank 220, and the anoxic tank 220 is connected to the aerobic tank 230. The aerobic tank 230 is connected to the sludge inlet pipe 265 through a sludge-water mixture pipeline 240. The other end of the sludge inlet pipe 265 is connected to the side-flow anaerobic reactor 280. A first drive pump 270 is also installed on the sludge inlet pipe 265. The side-flow anaerobic reactor 280 is connected to the aerobic tank 230 through a sludge outlet pipe 290 and a second drive pump 285. The aerobic tank 230 is also connected to the secondary sedimentation tank 250 through the sludge-water mixture pipeline 240. The bottom of the secondary sedimentation tank 250 is connected to the bottom of the anaerobic tank 210 through an outlet pipe 255. A third drive pump 260 is installed on the outlet pipe 255. An outlet 295 is also provided on the side wall of the secondary sedimentation tank 250. The aerobic tank 230 is also connected to the output pipeline 235 via the mud-water mixture pipeline 240. The output pipeline 235 is equipped with a fourth drive pump 245, and the other end of the output pipeline 235 is connected to the anoxic tank 220.

[0066] Figure 6The working principle of the device is as follows: Wastewater enters the anaerobic tank 210 from the wastewater outlet 205, and is further treated in the anoxic tank 220 and the aerobic tank 230. The sludge-water mixture at the end of the aerobic tank is returned to the anoxic tank 220 and then enters the secondary sedimentation tank 250 through pipeline 240 at a ratio of 3:1. After sludge-water separation in the secondary sedimentation tank 250, the effluent is discharged through the outlet 295. In this stage, only 95% of the sludge-water mixture enters the secondary sedimentation tank 250 through pipeline 240 or is returned to the anoxic tank 220. The remaining 5% of the sludge-water mixture is returned to the side-flow anaerobic reactor 280 through pipeline 240 along the sludge inlet pipe 265. The sludge after anaerobic treatment in the side-flow anaerobic reactor 280 flows into the aerobic tank 230 through the sludge outlet pipe 290 for further aerobic treatment. The underflow from the secondary sedimentation tank 250 can be fed back to the input end of the anaerobic tank 210 through the output pipe 255. The underflow can also be the output of the secondary sedimentation tank 250 for further solids treatment, such as thickening, stabilization, conditioning, dewatering, sludge treatment, etc., as is known to those skilled in the art.

[0067] Will Figure 6 The specific implementation steps of the device shown in the diagram for sludge reduction are as follows:

[0068] S1: Preprocessing:

[0069] To demonstrate the acclimatization and enhancement effect of the side-flow anaerobic reactor 280, a device consisting of a main anaerobic tank 210, an aerobic tank 230, a secondary sedimentation tank 250, and corresponding supporting pipelines, including the side-flow anaerobic reactor 280, is described. Figure 6 The experimental group (AS) consisted of a main anaerobic tank 210 (excluding the side-flow anaerobic reactor 280), an aerobic tank 230, a secondary sedimentation tank 250, and corresponding pipelines, serving as the control group (CK). Both groups were equipped with identical wastewater to simulate the influent quality of urban domestic sewage, ensuring its low carbon source characteristics. The influent COD was 170 mg / L, and NH4+ was... + -N: 10-25mg / L, TP: 1-2mg / L.

[0070] S2: Adjusting the mainstream anaerobic / aerobic ratio and selecting suitable microbial populations:

[0071] The hydraulic retention time of anaerobic tank 210 is adjusted to 2 hours, the hydraulic retention time of anoxic tank 220 is 2 hours, and the hydraulic retention time of aerobic tank 230 is 2 hours. The extended retention time of anaerobic tank is used to screen microorganisms with strong adaptability to store internal carbon sources, so as to promote material cycling and energy flow, maintain ecological balance, and enable them to effectively degrade environmental pollutants and promote the full treatment of waste, thereby facilitating the separation and enrichment of sludge.

[0072] S3: Optimized mainstream operation adjustments:

[0073] By adjusting operating conditions such as temperature, pH, and dissolved oxygen (DO), microorganisms were cultured at different temperatures, pH values, and residence times to select the optimal temperature for their growth and reproduction. The final screening results were: pH = 7.5, DO = 2-3 mg / L, T = 25℃.

[0074] S4: Implement synchronous extraction: During the treatment process, the activated sludge enriched in the secondary sedimentation tank 250 is periodically extracted for resource reuse or treatment and disposal, so that the enriched sludge is quickly separated and discharged from the system, thereby reducing the sludge retention time.

[0075] S5: Adjustment of the sludge circulation system in the side-flow anaerobic reactor 280: A side-flow anaerobic reactor 280 with a long sludge retention time (12 days) is introduced into the aerobic tank 230. The hydraulic retention time is 5 days, and the daily sludge exchange rate is 15%. The long-term anaerobic starvation environment of the side-flow anaerobic reactor 280 can further screen out denitrifying phosphorus-removing bacteria (DPAO) and denitrifying polysaccharide bacteria (DGAO) with internal carbon source storage functions, making them the dominant species. The sludge exchange frequency of the side-flow anaerobic reactor 280 is 6 times / day, which is the same as the first and second preset exchange frequencies of the side-flow anaerobic reactor 160. After the sludge enters the side-flow anaerobic reactor 280, aeration is increased once every 3 hours, with each aeration lasting for 2 minutes. Under intermittent aeration conditions, the decay rate of DGAO is greater than that of DPAO, thereby increasing the proportion of enriched PAO.

[0076] S6: Monitoring and Adjustment of Side-Flow Anaerobic Reactor 280: Regularly monitor the operating status of the side-flow anaerobic reactor 280 and the main biological selector, and adjust the operating parameters of the side-flow anaerobic reactor 280 in a timely manner to ensure the stability of indicators such as sludge concentration (2500-3500mg / L), microbial activity, pH (7-7.5), DO change (2-3mg / L), and effluent quality (Grade A).

[0077] S7: Research and Optimization: As the practice deepens, keeping other conditions unchanged, the retention time of anaerobic tank 210 is shortened from 2h to 1.7h, and the retention time of aerobic tank 23 is extended from 2h to 2.3h. The performance of seed sludge enriched by non-endogenous denitrifying bacteria (PhaseOL) and endogenous denitrifying bacteria (PhaseAL) in sludge reduction is compared.

[0078] Figure 7This figure shows the carbon source consumption and internal carbon source storage in the anaerobic tank 210, as well as the relative proportions of polyphosphate-accumulating bacteria (PAO) and polysaccharide-accumulating bacteria (GAO), in the control group (CK) and the experimental group (AS) containing a side-flow anaerobic reactor in this embodiment. It can be seen that the proportion of internal carbon sources in AS (outer ring) (91%) is higher than that in CK (inner ring) (80%), indicating that after adding the side-flow anaerobic reactor 280, more of the carbon source consumed in anaerobic tank 210 is stored as an internal carbon source by microorganisms, indirectly reflecting the increased enrichment of internal carbon source bacteria. The PAO proportion in AS (outer ring) is 11% higher than that in CK (inner ring), indicating that the intermittently aerated side-flow anaerobic reactor 280 increases the DPAO proportion.

[0079] Figure 8 The study investigated the sludge reduction effect of mainstream aerobic tank seed sludge enriched with non-endogenous denitrifying bacteria (PhaseOL) and endogenous denitrifying bacteria (PhaseAL). Results showed that shortening the retention time in anaerobic tank 210 to 1.7 h and extending the retention time in aerobic tank 230 to 2.3 h, resulting in enrichment of endogenous denitrifying bacteria (PhaseAL), led to a sludge reduction of 51.92%. However, enrichment of non-endogenous denitrifying bacteria (PhaseOL) resulted in a sludge reduction of only 36.79%. Furthermore, the increased microbial mortality in the return sludge of the side-flow anaerobic reactor 280 under aerobic conditions further enhanced the sludge reduction effect.

[0080] In summary, the denitrifying functional bacteria acclimation device with low carbon source influent and rich internal carbon source provided by this invention can utilize the mainstream in-situ low dissolved oxygen zone brought about by the sludge return from the side-flow anaerobic reactor. Combined with the prolonged anaerobic starvation environment of the side-flow anaerobic reactor, it can further screen out denitrifying phosphorus-removing bacteria (DPAO) and denitrifying polysaccharide bacteria (DGAO) with internal carbon source storage functions, making them the dominant species. Furthermore, the lower energy transfer efficiency of the side-flow anaerobic reactor results in a slower sludge growth rate, enabling rapid establishment of simultaneous nitrification, denitrification, and phosphorus removal, and stable operation with sludge reduction. Simultaneously, the high concentration of phosphate and ammonia nitrogen released from the anaerobic biomass in the side-flow anaerobic reactor ensures the P and N sources for DPAO and DGAO. The prolonged anoxic effect in the mainstream anaerobic and aerobic tanks ensures a higher ecological niche for the internal carbon source denitrifying functional bacteria. The side-flow anaerobic reactor eliminates microorganisms unsuitable for alternating environments; its accelerated death of mainstream microorganisms and their resulting latent growth achieve an in-situ sludge reduction effect of up to 50%. Furthermore, by changing the sludge return frequency or adding stirring and aeration equipment to the side-flow anaerobic reactor, the frequency and range of oxidation-reduction potential changes can be increased, thereby effectively achieving the differentiation of N and P microorganisms in the process to meet the denitrification and phosphorus removal requirements under different influent conditions. Therefore, the device and method for simultaneous sludge reduction through microbial enrichment under low-carbon-source influent provided by this invention have a simple process layout, require less land area for modification, and save energy. By fully utilizing the reducing power required for sludge return from the side-flow anaerobic reactor, the competition of aerobic heterotrophic microorganisms for dissolved oxygen and carbon sources can be avoided, thereby enriching DPAO or DGAO, ultimately achieving the enrichment of low-carbon-source microorganisms and sludge reduction, with better simultaneous denitrification effect.

[0081] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for simultaneous sludge reduction through microbial enrichment under low-carbon source influent, characterized in that, Includes the following steps: Wastewater enters the anaerobic tank and is further treated through the aerobic tank or the anoxic tank and the aerobic tank. The sludge-water mixture at the end of the aerobic tank enters the secondary sedimentation tank, or in a 3:1 ratio, part of it is returned to the anoxic tank and part of it enters the secondary sedimentation tank. After sludge-water separation in the secondary sedimentation tank, the effluent is discharged. In this stage, only 95% of the sludge-water mixture enters the secondary sedimentation tank or is returned to the anoxic tank. The remaining 5% of the sludge-water mixture is returned to the side-flow anaerobic reactor. The sludge after anaerobic treatment in the side-flow anaerobic reactor flows back into the aerobic tank for further aerobic treatment. The underflow from the secondary sedimentation tank is fed back to the input end of the anaerobic tank, and the underflow is the output of the secondary sedimentation tank. The specific operation of the above process includes the following steps: S1: Preprocessing: Choose suitable influent water quality, ensuring its low carbon source characteristics, with influent COD at 150-180 mg / L and NH4+ at 100 mg / L. + -N: 10-40mg / L, TP: 1-4mg / L; S2: Mainstream regulation of the anaerobic / aerobic ratio and selection of appropriate microbial populations: The ratio of hydraulic retention time between anaerobic and aerobic tanks is ≥1. Microorganisms with strong adaptability are screened to promote material cycling and energy flow, maintain ecological balance, and effectively degrade environmental pollutants and treat waste, thereby facilitating the separation and enrichment of sludge. S3: Optimized mainstream operation adjustments: By adjusting the temperature, pH, and dissolved oxygen (DO), microorganisms can be cultured at different temperatures, pH values, and residence times. The most suitable temperature, pH value, and residence time for microbial growth and reproduction can be selected, thereby promoting the growth and reproduction of carbon source microorganisms in the storage and adjusting the distribution of carbon sources. S4: Implement synchronous extraction: During the treatment process, the activated sludge enriched in the secondary sedimentation tank is extracted periodically for resource reuse or treatment and disposal, so that the enriched sludge is quickly separated and discharged from the system, thereby reducing the sludge retention time. S5: Adjust the sludge retention time of the side-flow anaerobic reactor to 10-15 days, and its hydraulic retention time to 3-10 days. The daily sludge exchange rate is 10-15%, and the sludge circulation frequency of the side-flow anaerobic reactor is 4-6 times / day to ensure the abundance of DPAO and DGAO and the stability of the system. S6: Sideflow Anaerobic Reactor Monitoring and Adjustment: Regularly monitor the operating status of the sideflow anaerobic reactor and the main biological selector, including changes in the concentration of organic matter in the wastewater, microbial activity, ORP, pH, DO, and effluent quality, and adjust the operating parameters of the sideflow anaerobic reactor in a timely manner to ensure the abundance of DPAO and DGAO and the stability of the system.

2. The method for simultaneous microbial enrichment and sludge reduction under low-carbon source influent as described in claim 1, characterized in that, In S2, the hydraulic retention time of the anaerobic tank is adjusted to 2.7 h, and the hydraulic retention time of the aerobic tank is adjusted to 2.3 h; or the hydraulic retention time of the anaerobic tank is adjusted to 2 h, the hydraulic retention time of the anoxic tank is adjusted to 2 h, and the hydraulic retention time of the aerobic tank is adjusted to 2 h.

3. The method for simultaneous microbial enrichment and sludge reduction under low-carbon source influent as described in claim 1, characterized in that, In S3, pH=7.5, DO=2-3mg / L, T=25℃.

4. The method for simultaneous microbial enrichment and sludge reduction under low-carbon source influent as described in claim 1, characterized in that, In S5, after the sludge enters the side-flow anaerobic reactor, aeration is added once every 2-3 hours, and the aeration duration is 2 minutes.

5. The method for simultaneous microbial enrichment and sludge reduction under low-carbon source influent as described in claim 1, characterized in that, In S6, adjusting the operating parameters of the side-flow anaerobic reactor includes adjusting the first preset exchange frequency and the second preset exchange frequency of the side-flow anaerobic reactor, both of which are 4-6 times / day. The basis for adjusting the operating parameters of the side-flow anaerobic reactor includes a sludge concentration of 2500-3500 mg / L, pH=7-7.5, DO change of 2-3 mg / L, and effluent quality of Class A standard.

6. The application of the microbial enrichment and simultaneous sludge reduction method under low carbon source influent as described in claim 1 in the reduction of sludge in urban domestic sewage.

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