Sewage treatment method capable of reducing sludge production

Abstract

The invention discloses a sewage treatment method capable of reducing sludge production, which comprises the following steps: S1, sewage firstly enters an anaerobic hydrolysis reactor for hydrolytic acidification, and then the sewage enters an anaerobic sludge interception reactor; s2, carrying out nitrogen and phosphorus removal and organic matter degradation on the water treated in the step S1; s3, the water body subjected to biochemical treatment in the step S2 enters a secondary sedimentation tank, and solid-liquid separation is completed; s4, residual sludge discharged from the secondary sedimentation tank and the anaerobic sludge interception reactor is collected in a sludge tank and then enters a sludge concentration tank, and the water content of the sludge is reduced; s5, the concentrated sludge enters a special aerobic starvation reactor; s6, dehydrating equipment is used, and the treated mud cakes are made into dry and hard mud cakes. According to the method, the sludge yield is reduced from the source, and the potential pressure on the environment is fundamentally relieved; no harmful chemical agent is added in the process, so that secondary pollution is avoided; the reduced sludge is more stable, and favorable conditions are created for subsequent safe resource utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sewage treatment, and particularly relates to a sewage treatment method capable of reducing sludge production. BACKGROUND

[0002] The residual sludge has complex components, contains pathogenic bacteria, heavy metals and organic pollutants, and if not properly treated, can easily cause secondary pollution.

[0003] At present, the traditional activated sludge method and its improved process (such as A2 / O, oxidation ditch, SBR, etc.) widely used at home and abroad have the core goal of removing pollutants (COD, BOD, nitrogen and phosphorus) in water, but the control of sludge production is insufficient.

[0004] These processes usually have the following problems: high sludge yield: during the degradation of pollutants by microorganisms, 30%-60% of organic matter is usually converted into new cell material (residual sludge), resulting in a large amount of sludge production. The sludge yield coefficient (Yobs) of conventional processes is usually 0.8-1.2 kgDS / kg Removal. Environmental risk is prominent: landfilling of sludge occupies a large amount of land resources, and there is a risk of leachate and biogas pollution; incineration is easy to produce dioxin and other toxic substances; if the heavy metal content of the compost product exceeds the standard, it is difficult to be used for agriculture To deal with the sludge problem, the industry has developed various sludge reduction technologies, but there are certain defects: Physical / chemical methods (such as ozone, ultrasonic, pyrolysis, etc.): usually need to add reagents or consume a large amount of energy, with high equipment investment and operation cost, and may produce harmful intermediate products, which is difficult to be applied on a large scale.

[0005] Pure membrane method (such as MBR): although the sludge discharge amount is reduced by long sludge age, high-concentration sludge stays in the system, resulting in increased aeration energy consumption, serious membrane pollution and complex operation and management, which is essentially a delay rather than a reduction in the final sludge production.

[0006] Single aerobic / anaerobic digestion: this is the most commonly used sludge stabilization technology at present, but its main purpose is to stabilize the sludge rather than to reduce the amount, and the reduction effect is limited (usually only 20%-30%), and the residence time is long (15-30 days), and the tank capacity requirement is large.

[0007] In summary, the existing technology either focuses on "end treatment" and fails to control sludge production from the source, or although it can reduce the amount, but has problems such as high cost, low efficiency, unstable operation or possible secondary pollution. SUMMARY

[0008] To this end, the present application provides a sewage treatment method capable of realizing sludge source reduction in the sewage biochemical treatment process, efficiently coupling with end treatment, and reducing sludge production, so as to solve the problems in the prior art.

[0009] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: A sewage treatment method capable of reducing sludge production, comprising the following steps: S1: The sewage first enters an anaerobic hydrolysis reactor for hydrolysis acidification, and then enters an anaerobic sludge interception reactor for preliminary separation of sludge and water; the high-concentration anaerobic sludge with a concentration of more than 60% after separation is returned to the front end of the anaerobic hydrolysis reactor; S2: The water treated in step S1 enters a primary anoxic reactor, a primary aerobic reactor, an oxygen-consuming reactor, a secondary anoxic reactor and a secondary aerobic reactor in sequence to complete denitrification and phosphorus removal and organic matter degradation; S3: The water body treated by the multi-stage anoxic-aerobic biochemical treatment in step S2 enters a secondary sedimentation tank for complete solid-liquid separation; S4: The residual sludge discharged from the secondary sedimentation tank and the anaerobic sludge interception reactor is collected in a sludge tank and then enters a sludge thickening tank to reduce the water content of the sludge; S5: The thickened sludge enters a dedicated aerobic starvation reactor; S6: The sludge treated by the aerobic starvation treatment; using a dewatering device, the sludge is dewatered to a water content of less than 60% to form a dry hard mud cake.

[0010] Further: the residence time of the sewage in the anaerobic hydrolysis reactor needs to be controlled to be 4-8 hours; at the same time, a complete anaerobic environment is maintained.

[0011] Further: the specific implementation of S2 is: The primary anoxic zone utilizes the carbon source in the influent and the nitrate returned from the aerobic zone for denitrification; the mixed liquid return ratio is controlled to be 100%-200%; The primary aerobic zone performs oxidative degradation of organic matter and nitrification of ammonia nitrogen; suspended biological fillers are added in this zone to form a biofilm-activated sludge composite system; the dissolved oxygen is controlled to be 2.0-3.0 mg / L; The oxygen-consuming zone reduces the dissolved oxygen in the water; The secondary anoxic / aerobic zone further removes residual organic matter to ensure the water quality of the effluent.

[0012] Further: in S3, more than 50% of the sludge is returned to the front end of the primary anoxic reactor by a return pump to maintain the required amount of microorganisms in the biochemical system; the remaining part is discharged as residual sludge to the sludge tank.

[0013] Further: in the S3, the surface load of the secondary sedimentation tank needs to be controlled; at the same time, the sludge layer thickness and concentration are monitored online through a sludge concentration meter.

[0014] Further: in the S4, the specific implementation of reducing the water content of the sludge is: through gravity concentration or mechanical concentration, the water content of the sludge is reduced from 99.2%-99.5% to 95%-97%.

[0015] Further: in the S5, the specific implementation cycle of the aerobic starvation reactor includes: The sludge is received in the sludge inlet period; In the starvation reaction period, the intermittent aeration mode is adopted; during the aeration period, the DO is controlled at 2.0-3.0 mg / L, and a small amount of oxygen is supplied to maintain the basic activity of microorganisms; during the non-aeration period, the microorganisms are in a "starvation state" and are forced to start endogenous respiration, consuming their own stored substances and even cell components; In the sedimentation period, stirring and aeration are stopped to allow the sludge to settle; In the drainage / sludge discharge period, the supernatant is discharged and returned to the front end of the biochemical system as a nutrient source, and the reduced and stabilized sludge at the bottom is discharged for final disposal.

[0016] Further: in the S5, the indicators of the sludge in the reactor need to be detected regularly to evaluate the starvation degree, and the aeration / non-aeration time ratio and the total starvation period are optimized accordingly.

[0017] Further: the dry and hard mud cake can be used for aerobic composting, building material utilization, and sanitary landfill.

[0018] In order to achieve the above purpose, the present application also provides a sewage treatment system capable of reducing the production of sludge, which comprises an intelligent control and decision center and a core treatment and resource recovery unit.

[0019] The intelligent control and decision center can realize intelligent decision and optimization based on data and models, and constitutes the nerve center of the whole system.

[0020] The intelligent control and decision center comprises real-time data acquisition and monitoring, digital twin models, and AI intelligent decision platforms.

[0021] The real-time data acquisition and monitoring continuously collects all key process parameters through a sensor network distributed throughout the plant; the sensor network includes flow meters, pH meters, dissolved oxygen DO meters, oxidation-reduction potential ORP meters, sludge concentration meters MLSS, ammonia nitrogen / nitrate online analyzers, etc.

[0022] Digital twin model, based on real data collected by SCADA system, builds a dynamic virtual model corresponding to the physical plant in the server; this dynamic virtual model can simulate and predict the operation effect of the entire biochemical reaction system and sludge treatment system under different conditions such as influent load, temperature, and reflux ratio.

[0023] AI intelligent decision-making platform, integrating process knowledge base, machine learning algorithm and optimization model, receives real-time data from SCADA and prediction data from digital twin, and automatically generates optimal operation instructions through deep analysis by AI algorithms such as fuzzy control, neural network, and expert rules.

[0024] Core processing and resource recovery unit, through multi-stage biochemical reaction zone, sludge treatment and starvation control zone, to achieve sludge reduction.

[0025] The specific implementation process of the multi-stage biochemical reaction zone includes: Anaerobic hydrolysis and sludge interception, wastewater first enters the anaerobic hydrolysis reactor. Here, by strictly controlling the hydraulic retention time (HRT for 4-6 hours) and oxidation reduction potential (ORP <-250 mV), a highly efficient completely anaerobic environment is created. Facultative and anaerobic microorganisms decompose and convert the refractory macromolecular organic matter (such as carbohydrates, proteins, fats) in wastewater into easily degradable substances (i.e. hydrolytic acidification) such as small molecular organic acids and alcohols. This step not only improves the biodegradability of wastewater, but also provides high-quality carbon source for subsequent denitrification and phosphorus removal. Subsequently, the wastewater enters the anaerobic sludge interception reactor with built-in membrane separation or sedimentation device, achieving preliminary separation of sludge and water. High-concentration anaerobic sludge is returned to the front-end anaerobic hydrolysis reactor in large quantities, maintaining the mixed liquor suspended solids concentration (MLSS) at an extremely high level of 15-30 g / L.

[0026] Multi-stage anoxic-aerobic biochemical treatment, pretreated water flows through the first anoxic zone, the first aerobic zone, the oxygen depletion zone, the second anoxic zone and the second aerobic zone in turn. The multi-stage environmental changes make the microorganisms under various environmental pressures, and their energy is more consumed in stress and survival maintenance rather than proliferation, further reducing the sludge yield.

[0027] The specific implementation process of the sludge treatment and starvation control zone includes: Sludge and water separation and sludge return: the mixed liquor after biochemical treatment enters the secondary sedimentation tank for final solid-liquid separation. By controlling the surface load, ensure good sedimentation of sludge. Most of the settled sludge is returned to the front end of the biochemical system to maintain sufficient microbial amount; only a small part is discharged as excess sludge. Due to the effect of "process reduction" in the previous stage, the production of this part of excess sludge is much lower than that of traditional processes.

[0028] Concentration of excess sludge: After the excess sludge discharged from the secondary sedimentation tank and the anaerobic interception system is collected in the sludge tank, it enters the concentration tank (by gravity or mechanically) to reduce the water content from more than 99.2% to 95%-97%. This step reduces the volume of the subsequent treatment unit, improves the treatment efficiency, and concentrates the substrate, enhancing the effect of the starvation treatment.

[0029] Oxygen starvation reaction: The concentrated sludge enters the oxygen starvation reactor designed in the sequencing batch (SBR) mode.

[0030] Energy and resource recovery unit: The "waste" generated during the sewage sludge treatment process is recovered and utilized; including biogas utilization, potential chemical recovery, and nutrient-rich dewatered sludge recovery.

[0031] Biogas utilization: During the anaerobic hydrolysis stage, part of the organic matter will ferment to produce biogas mainly composed of methane. This part of the biogas can be collected for power generation or heat production, providing part of the energy for the plant area and reducing operating costs.

[0032] Nutrient-rich dewatered sludge recovery: After the oxygen starvation treatment, the sludge is highly stable in nature, the organic matter content is greatly reduced, and the pathogenic bacteria are killed. After being treated by high-efficiency equipment such as a plate-frame dewatering machine, the water content can be easily reduced to below 60%, forming a dry and hard mud cake. This mud cake is rich in nitrogen, phosphorus, potassium, and organic matter, and is a high-quality soil conditioner that can be directly used for landscaping composting.

[0033] Potential chemicals (such as PHA): During the starvation regulation process, microorganisms accumulate PHA (polyhydroxyalkanoate, a precursor of biodegradable plastic) in their bodies under certain conditions. In the future, PHA can be recovered by process optimization, realizing the high-value resource utilization of sludge.

[0034] The present application has the following advantages: The present application reduces the sludge production from the source, fundamentally reducing the potential pressure on the environment; no harmful chemicals are added during the process, and no secondary pollution is generated; the reduced sludge is more stable, creating favorable conditions for subsequent safe resource utilization (such as composting).

[0035] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0036] To more intuitively illustrate the prior art and this application, exemplary drawings are provided below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing this application; for example, based on the technical concept disclosed in this application and the exemplary drawings, those skilled in the art are able to easily make conventional adjustments or further optimizations to the addition / reduction / classification, specific shapes, positional relationships, connection methods, size ratios, etc. of certain units (components).

[0037] Figure 1 This is a flowchart illustrating a wastewater treatment method that can reduce sludge production, as provided in one embodiment of this application.

[0038] Figure 2 This is a block diagram of the architecture of a wastewater treatment system that can reduce sludge production according to the present invention. Detailed Implementation

[0039] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. It should be understood that these embodiments are merely for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Technical engineers in the field can make some non-essential improvements and adjustments to the present invention based on the above-described content. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Please see Figure 1 A wastewater treatment method that can reduce sludge production includes the following steps: S1: Anaerobic hydrolysis and sludge retention. Wastewater first enters the anaerobic hydrolysis reactor. In this stage, large organic molecules are decomposed into small organic acids, alcohols and other easily degradable substances by facultative and anaerobic microorganisms. This process is called "hydrolysis acidification".

[0041] Specifically: the wastewater retention time (HRT) in the anaerobic hydrolysis reactor needs to be controlled to be 4-6 hours; at the same time, a completely anaerobic environment should be maintained, i.e., the oxidation-reduction potential (ORP) < -250mV.

[0042] Wastewater then enters an anaerobic sludge retention reactor (such as one with a built-in membrane separator or sedimentation device) to achieve initial separation of sludge and water. Most of the high-concentration anaerobic sludge after separation is returned to the upstream anaerobic hydrolysis reactor to maintain extremely high biomass concentrations (MLSS can reach 15-30 g / L).

[0043] In this step, recalcitrant organic matter can be converted into readily biodegradable organic matter, providing a high-quality carbon source for subsequent biochemical treatment. At the same time, by maintaining high biomass through sludge recirculation, microorganisms can grow in an environment of alternating "fullness" and "starvation," reducing sludge yield from the metabolic source.

[0044] S2: Multi-stage anoxic-aerobic biochemical treatment. The water treated in step S1 enters the first-stage anoxic reactor, the first-stage aerobic reactor, the deoxygenation reactor, the second-stage anoxic reactor, and the second-stage aerobic reactor in sequence to complete nitrogen and phosphorus removal and organic matter degradation.

[0045] The specific implementation steps are as follows: In the primary anoxic zone, denitrification is carried out using the influent carbon source and nitrates returned from the aerobic zone; the mixed liquor recirculation ratio (recirculated from the deoxygenated zone or the end of the aerobic zone to the anoxic zone) is usually controlled at 100%-200%.

[0046] The primary aerobic zone is used for the oxidative degradation of organic matter and the nitrification of ammonia nitrogen. Suspended biological packing material is added to this zone to form a biofilm-activated sludge composite system. Dissolved oxygen (DO) is controlled at 2.0-3.0 mg / L.

[0047] The deoxygenation zone reduces dissolved oxygen in the water, creating favorable conditions for subsequent secondary anoxic denitrification.

[0048] The secondary anoxic / aerobic zone further denitrifies and removes residual organic matter to ensure the quality of the effluent.

[0049] In this process, the carbon source is first used for denitrification in the anoxic zone, and then oxidized in the aerobic zone, maximizing efficiency.

[0050] In the aerobic zone, protozoa and metazoa enriched on the biofilm prey on free bacteria, significantly reducing the total amount of sludge. In addition, the multi-level environment puts microorganisms under various stresses, and they use more energy to maintain life rather than to proliferate, resulting in a significant reduction in the sludge yield coefficient.

[0051] S3: Sludge-water separation and sludge return. After multi-stage anoxic-aerobic biochemical treatment, the water enters the secondary sedimentation tank for thorough solid-liquid separation.

[0052] Control the surface load of the secondary sedimentation tank to ensure good settling effect; monitor the sludge layer thickness and concentration online using a sludge concentration meter.

[0053] Most of the sludge is returned to the front end of the primary anoxic reactor via a return pump to maintain the microbial biomass required by the biochemical system. The sludge return ratio is generally 50%-100%. A small portion is discharged from the system as excess sludge and sent to the sludge tank. Due to the process reduction effect, the sludge production of this portion is significantly lower than that of traditional processes.

[0054] S4: Thickening of excess sludge. The excess sludge discharged from the secondary sedimentation tank and anaerobic sludge interception reactor is collected in the sludge tank and then enters the sludge thickening tank.

[0055] By using gravity or mechanical thickening, the moisture content of sludge is reduced from 99.2%-99.5% to 95%-97% (i.e., the solids content is increased from 0.5%-0.8% to 3%-5%). The purpose is to increase the sludge concentration, reduce the volume of the subsequent starvation reactor, and enhance the effect of starvation treatment.

[0056] S5: The concentrated sludge enters a dedicated aerobic starvation reactor, which is generally designed as a sequencing batch reactor (SBR).

[0057] Taking a 24-hour period as an example: During the sludge infeeding period (0.5 hours), a batch of concentrated sludge is received.

[0058] During the starvation response period (22-23 hours), an intermittent aeration mode is adopted, for example: aerate for 2 hours and stop for 2 hours. During the aeration period, DO is controlled at 2.0-3.0 mg / L, and trace amounts of oxygen are supplied to maintain the basic activity of microorganisms. During the aeration stop period, microorganisms fall into a "starvation state" and are forced to start endogenous respiration, consuming their own stored substances (such as glycogen, PHA) and even cell components.

[0059] During the settling period (0.5-1 hour), stop stirring and aeration to allow the sludge to settle.

[0060] During the drainage / sludge removal period (0.5 hours), the supernatant, which is rich in nitrogen and phosphorus, is discharged and can be returned to the front end of the biological system as a nutrient source. The reduced and stabilized sludge at the bottom is discharged for final disposal.

[0061] In addition, it is necessary to regularly test indicators such as lactate dehydrogenase (LDH) activity and ATP content in the sludge in the reactor to assess the degree of starvation and optimize the aeration / stop time ratio and total starvation cycle accordingly, which usually lasts for 7-10 days.

[0062] S6: Final disposal and resource utilization. The sludge after aerobic starvation treatment is stable and the organic matter content is significantly reduced. Using efficient dewatering equipment such as plate and frame dewatering machines, the sludge can be easily dewatered to a moisture content of less than 60% to form a dry and hard sludge cake.

[0063] Because the sludge is highly mineralized and stabilized, it can be safely used for: aerobic composting to produce soil for landscaping; building materials utilization as raw material for co-processing in cement kilns or as an additive for brick making; and sanitary landfill, which significantly reduces landfill volume and lowers environmental risks.

[0064] See Figure 2A wastewater treatment system that implements the aforementioned wastewater treatment method that can reduce sludge production includes an intelligent control and decision-making center and a core treatment and resource recovery unit.

[0065] The intelligent control and decision-making center enables intelligent decision-making and optimization based on data and models; it constitutes the nerve center of the entire system.

[0066] The intelligent control and decision-making center includes real-time data acquisition and monitoring, digital twin models, and an AI intelligent decision-making platform.

[0067] The real-time data acquisition and monitoring (SCADA system) continuously collects all key process parameters through a sensor network distributed throughout the plant. The sensor network includes flow meters, pH meters, dissolved oxygen (DO) meters, oxidation-reduction potential (ORP) meters, sludge concentration meters (MLSS), and online ammonia nitrogen / nitrate analyzers.

[0068] The SCADA system aggregates, displays, stores, and generates initial alarms for this massive amount of real-time data, providing operators and advanced decision-making platforms with a panoramic view of the instantaneous operational status of the entire process, ensuring the visualization and transparency of the process.

[0069] The digital twin model is a dynamic virtual model built on a server based on real data collected by the SCADA system, which is completely corresponding to the physical plant. This dynamic virtual model can simulate and predict the operating effects of the entire biochemical reaction system and sludge treatment system under different influent loads, temperatures, reflux ratios and other conditions.

[0070] For example, it can predict the impact of adjusting the aeration rate in the aerobic zone on effluent quality and energy consumption, or simulate the sludge reduction effect of a starved reactor under different operating cycles. Through "what-if analysis," digital twin models become a powerful tool for process optimization and decision support, allowing for virtual commissioning and optimization without affecting actual production.

[0071] AI Intelligent Decision Platform (Expert System): Integrating process knowledge base, machine learning algorithms and optimization models, the AI ​​Intelligent Decision Platform receives real-time data from SCADA and predictive data from digital twins, performs in-depth analysis through AI algorithms (such as fuzzy control, neural networks, and expert rules), and automatically generates optimal operating instructions.

[0072] For example, when the system predicts insufficient carbon source in the influent, the AI ​​platform may instruct a portion of the carbon-rich supernatant to be returned from the sludge-starved reactor to the front-end anoxic zone; or it may dynamically adjust the frequency of the aerators based on the real-time ammonia nitrogen load in the aerobic zone to achieve precise aeration, maximizing energy savings while ensuring treatment effectiveness. It models and codes the experience of senior engineers, enabling uninterrupted intelligent optimization 24 / 7.

[0073] The intelligent control and decision-making center uses full-process data-driven model simulation and optimization. The optimization results are analyzed and judged by the AI ​​intelligent decision-making platform, and finally the executable decision instructions are issued to the pumps, valves, fans and other execution equipment on site. The effect after execution is fed back as new data through sensors. This cycle continues, so that the system always keeps running under the optimal operating conditions.

[0074] The core processing and resource recovery unit reduces sludge volume through multi-stage biochemical reaction zones, sludge treatment zones, and starvation control zones.

[0075] The specific implementation process of a multi-stage biochemical reaction zone includes: Anaerobic hydrolysis and sludge retention: Wastewater first enters the anaerobic hydrolysis reactor. Here, a highly efficient, completely anaerobic environment is created by strictly controlling the hydraulic retention time (HRT of 4-6 hours) and oxidation-reduction potential (ORP < -250mV). Facultative and anaerobic microorganisms decompose recalcitrant macromolecular organic matter (such as carbohydrates, proteins, and fats) in the wastewater into easily degradable substances such as small-molecule organic acids and alcohols (i.e., hydrolysis and acidification). This step not only improves the biodegradability of the wastewater but also provides a high-quality carbon source for subsequent nitrogen and phosphorus removal. Subsequently, the wastewater enters the anaerobic sludge retention reactor with an integrated membrane separation or sedimentation device to achieve preliminary separation of sludge and water. High-concentration anaerobic sludge is largely recycled back to the upstream anaerobic hydrolysis reactor, maintaining the mixed liquor suspended solids (MLSS) concentration (MLSS) at an extremely high level of 15-30 g / L. This high concentration of sludge and the alternating environment of "fullness (hydrolysis and acidification) - starvation (entering subsequent aerobic conditions)" prompts microorganisms to use more energy to maintain life rather than synthesize new cells, significantly reducing the sludge yield coefficient from the metabolic source.

[0076] Multi-stage anoxic-aerobic biological treatment: Pretreated water flows sequentially through a primary anoxic zone, a primary aerobic zone, a deoxygenation zone, a secondary anoxic zone, and a secondary aerobic zone. In the primary anoxic zone, the carbon source in the influent undergoes denitrification with the nitrate-containing mixed liquor returned from the aerobic zone, converting nitrate nitrogen into nitrogen gas for removal. In the primary aerobic zone, further oxidation of organic matter and nitrification of ammonia nitrogen occur. Suspended biological packing is added to this zone, forming a composite system of activated sludge and biofilm. The biofilm is enriched with a large number of micro-predators such as protozoa and metazoa, which prey on free bacteria in the water, forming a "food chain" effect that transforms bacterial biomass into higher-level organisms, thereby significantly reducing the total sludge volume in the system. The deoxygenation zone consumes excess dissolved oxygen in the water, creating favorable conditions for denitrification in the secondary anoxic zone. Multi-level environmental changes put microorganisms under various environmental pressures, causing them to consume more energy for stress and survival rather than for proliferation, which further reduces sludge production.

[0077] The specific implementation process of sludge treatment and starvation control zone includes: Sludge-water separation and sludge return: The mixed liquor after biological treatment enters the secondary settling tank for final solid-liquid separation. Surface loading is controlled to ensure good sludge settling. Most of the settled sludge is returned to the front end of the biological system to maintain sufficient microbial biomass; only a small portion is discharged as excess sludge. Due to the "process reduction" effect in the upstream stage, the yield of this excess sludge is far lower than in traditional processes.

[0078] Sludge thickening: After being collected in the sludge tank, the excess sludge discharged from the secondary sedimentation tank and anaerobic interception system enters the thickening tank (by gravity or mechanical means) to reduce the moisture content from over 99.2% to 95%-97%. This step reduces the volume of subsequent treatment units, improves treatment efficiency, and concentrates the substrate, thus enhancing the effect of starvation treatment.

[0079] Aerobic starvation reaction: This is the core step in sludge reduction at the end of the process. The concentrated sludge enters an aerobic starvation reactor designed as a sequencing batch reactor (SBR). A typical 24-hour cycle includes four stages: sludge inlet, starvation reaction, sedimentation, and sludge discharge / removal. During the 22-23 hour starvation reaction period, intermittent aeration is used, such as "2 hours of aeration, 2 hours of aeration stoppage." During aeration, trace amounts of oxygen (DO 2.0-3.0 mg / L) are provided to maintain basic microbial activity; during aeration stoppage, external carbon sources are extremely scarce, forcing microorganisms into an "endogenous respiration" state, decomposing and consuming their own intracellular glycogen, polyhydroxyalkanoates (PHAs), and even decomposing cellular components to obtain energy, thus leading to a substantial reduction in sludge volume (volatile solids vs. volatile organic compounds). The entire starvation process typically lasts 7-10 days and is precisely controlled by monitoring physiological indicators such as lactate dehydrogenase (LDH) activity and ATP content. The discharged supernatant, rich in nitrogen and phosphorus, can be returned to the main biological system as a nutrient supplement.

[0080] Energy and resource recovery unit: Recovers and utilizes "waste" generated during wastewater and sludge treatment; including biogas utilization, potential chemical recovery, and nutrient-rich dewatered sludge recovery.

[0081] In the anaerobic hydrolysis stage of biogas utilization, some organic matter ferments to produce biogas, mainly methane. This biogas can be collected and used for power generation or heat production, providing some energy to the plant and reducing operating costs.

[0082] Nutrient-rich dewatered sludge recycling involves sludge that has undergone aerobic starvation treatment, resulting in highly stable properties, significantly reduced organic matter content, and the elimination of pathogens. Further processing with efficient equipment such as plate and frame dewatering machines easily reduces the moisture content to below 60%, forming dry, hardened sludge cakes. These cakes are rich in nitrogen, phosphorus, potassium, and organic matter, making them excellent soil conditioners that can be directly used for landscaping composting.

[0083] Potential chemicals (such as PHA): During starvation regulation, microorganisms accumulate PHA (polyhydroxyalkanoate, a precursor to biodegradable plastics) in their bodies under specific conditions. In the future, PHA can be selectively recycled through process optimization, achieving high-value resource utilization of sludge.

[0084] Water that has undergone the above-mentioned strict treatment is clear and stable, meeting or even exceeding national discharge standards. It can be reused as reclaimed water for urban greening, industrial cooling, or ground washing, or it can be safely discharged into natural water bodies. Example

[0085] A wastewater treatment plant in a high-concentration food industrial park; with a daily treatment capacity of 10,000 tons.

[0086] Water quality characteristics: High COD concentration in influent (2000-5000 mg / L). A high COD / S ratio (>0.5) indicates good biodegradability, but water quality and quantity fluctuate greatly, and traditional processes produce huge amounts of sludge.

[0087] Core process route: Enhanced hydrolysis acidification + multi-stage A / O + aerobic starvation.

[0088] Detailed design: Hydrolysis acidification tank: A submersible agitator is added, and the HRT is extended to 12 hours to fully convert macromolecular organic matter (starch, protein, fat) into volatile fatty acids (VFAs), providing a high-quality carbon source for subsequent denitrification.

[0089] Biochemical system: A two-stage A / O design is adopted, prioritizing the use of carbon sources for denitrification. The aerobic zone is also enriched with packing material to produce a biofilm.

[0090] Sludge treatment: All remaining sludge is introduced into a continuous flow aerobic starvation tank (HRT=15 days) for stabilization and volume reduction. The tank is equipped with aeration and underwater propulsion devices to prevent sludge settling.

[0091] Strategy to mitigate fluctuations: The hydrolysis acidification tank is used as a conditioning tank to smooth out water quality fluctuations. The intelligent system automatically adjusts the aeration intensity of the starvation tank based on online COD meter data. Implementation effect

[0092] The sludge yield coefficient was reduced; the organic matter (COD) in the wastewater was successfully converted mainly through biogas (generated by hydrolysis acidification and anaerobic digestion units) and endogenous respiration (starvation reduction), rather than being converted into excess sludge. In addition, the entire wastewater treatment system has strong resistance to shock loads, and the effluent consistently meets standards. Example

[0093] A small-scale sewage treatment plant in a scenic tourist area; with a daily treatment capacity of 500 tons.

[0094] Requirements: Small footprint, environmentally friendly (underground), aesthetically pleasing, highly automated, and sludge can be treated on-site to avoid long-distance transportation.

[0095] Implementation of technical solution: It adopts highly integrated, modular equipment.

[0096] System composition: The core process is "pretreatment + A / O biofilm (MBBR) + membrane bioreactor (MBR) + integrated aerobic sludge digestion chamber".

[0097] Workflow: After passing through the screen, the wastewater enters the A / O-MBBR zone within the integrated equipment for the removal of carbon, nitrogen, and phosphorus. MBR membrane tanks replace secondary sedimentation tanks, achieving efficient separation of mud and water, and the effluent can be reused after disinfection (such as for landscaping). The small amount of residual sludge produced by the MBR tank is automatically pumped into the "integrated aerobic sludge digestion chamber" at the top of the equipment. This chamber is small in size, but it continuously "aerobic starvation" the sludge through efficient aeration and long SRT (up to 30 days or more).

[0098] The entire system is automatically controlled by PLC and remotely monitored through a cloud platform, achieving "unattended operation". Implementation effect

[0099] Sludge reduction and disposal: The sludge production rate is extremely low, and the sludge in the integrated digestion chamber needs to be cleaned less often each year. The cleaned sludge is highly mineralized and stable, and can be used as safe nutrient soil for nearby green spaces for on-site disposal, completely solving the pain point of difficult sludge disposal in small-scale facilities.

[0100] The underground design allows for landscaping above ground, resulting in good environmental harmony. Water reuse conserves water resources and significantly reduces the difficulty and cost of operation and maintenance in remote areas.

[0101] The technology of this invention is a creative integration and optimization of existing mature process units (A / O, biofilm, sludge thickening), rather than a disruptive change, so it has high engineering feasibility and stable operation.

[0102] By introducing online water quality / sludge level instruments, PLCs, and intelligent algorithms (such as predictive control based on digital twins), precise automatic control of key parameters (DO, reflux ratio, sludge discharge, starvation cycle) has been achieved, reducing reliance on operator experience and realizing "intelligent" operation.

[0103] This reduces sludge production at the source, fundamentally alleviating potential environmental pressure; no harmful chemicals are added during the process, and no secondary pollution is generated; the reduced sludge is more stable, creating favorable conditions for subsequent safe resource utilization (such as composting), and promoting the transformation of sewage treatment plants from "pollution control" to "resource recycling".

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A sewage treatment method capable of reducing sludge production, characterized by, The method comprises the following steps: S1: sewage first enters an anaerobic hydrolysis reactor for hydrolysis acidification, and then enters an anaerobic sludge interception reactor for preliminary separation of sludge and water; the high-concentration anaerobic sludge with a concentration of more than 60% is returned to the front end of the anaerobic hydrolysis reactor; S2: the water treated in step S1 enters a first-stage anoxic reactor, a first-stage aerobic reactor, an oxygen-consuming reactor, a second-stage anoxic reactor and a second-stage aerobic reactor in sequence to complete denitrification and phosphorus removal and degradation of organic matter; S3: the water body treated in step S2 enters a secondary sedimentation tank for complete solid-liquid separation; S4: the residual sludge discharged from the secondary sedimentation tank and the anaerobic sludge interception reactor is collected in a sludge tank, enters a sludge thickening tank to reduce the water content of the sludge; S5: the thickened sludge enters a special aerobic starvation reactor; S6: the sludge treated in the aerobic starvation reactor; The sludge is dewatered to a water content of less than 60% by using a dewatering device to form a dry hard mud cake.

2. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, The residence time of the sewage in the anaerobic hydrolysis reactor needs to be controlled to be 4-8 hours; at the same time, a complete anaerobic environment is maintained.

3. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, The specific embodiment of S2 is as follows: In the first-stage anoxic zone, denitrification is performed by using the carbon source in the influent and nitrate returned from the aerobic zone; the return sludge ratio is controlled to be 100%-200%; In the first-stage aerobic zone, oxidative degradation of organic matter and nitrification of ammonia nitrogen are performed; The suspended biological filler is added in this zone to form a biofilm-activated sludge composite system; the dissolved oxygen is controlled to be 2.0-3.0 mg / L; In the oxygen-consuming zone, the dissolved oxygen in the water is reduced; In the second-stage anoxic / aerobic zone, further deep denitrification and removal of residual organic matter are performed to ensure the water quality of the effluent.

4. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, In S3, more than 50% of the sludge is returned to the front end of the first-stage anoxic reactor by a return pump to maintain the required amount of microorganisms in the biochemical system; the remaining part is discharged as residual sludge to the sludge tank.

5. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, In S3, the surface load of the secondary sedimentation tank needs to be controlled; at the same time, the thickness and concentration of the sludge layer are monitored on line by using a sludge concentration meter.

6. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, In S4, the specific embodiment for reducing the water content of the sludge is as follows: the water content of the sludge is reduced from 99.2%-99.5% to 95%-97% by gravity thickening or mechanical thickening.

7. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, In S5, the specific implementation cycle of the aerobic starvation reactor includes the following steps: In the sludge feeding stage, a batch of thickened sludge is received; In the starvation reaction stage, intermittent aeration is adopted; during the aeration period, the DO is controlled to be 2.0-3.0 mg / L to supply a small amount of oxygen to maintain the basic activity of the microorganisms; during the non-aeration period, the microorganisms are forced to start endogenous respiration to consume the stored substances and even the cell components; In the sedimentation stage, stirring and aeration are stopped to allow the sludge to settle; In the water drainage / sludge discharge stage, the supernatant is discharged and returned to the front end of the biochemical system as a nutrient source; the reduced and stabilized sludge at the bottom is discharged for final disposal.

8. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, In S5, the indicators of the sludge in the reactor need to be detected regularly to evaluate the starvation degree and optimize the aeration / non-aeration time ratio and the total starvation cycle.

9. The sewage treatment method capable of reducing sludge production amount according to claim 1, characterized by, The dry hard mud cake can be used for aerobic composting, building material utilization and sanitary landfill.

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