Lateral flow sewage treatment system with self-adaptive carbon-nitrogen ratio and sludge reduction method

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses a lateral flow sewage treatment system and method with a self-adaptive carbon-nitrogen ratio. The system comprises a mainstream reactor, a sidestream reactor, a monitoring unit, an intelligent control unit, a reflux path switching device and a microbial agent targeted adding system. The method comprises the following steps: monitoring inlet water C / N in real time, and intelligently switching an operation mode, parameters, a microbial agent adding strategy and an outlet water backflow path of ASSR: when the C / N is low, starting a recessive growth mode, returning the outlet water to an anaerobic zone, and preferentially supplementing carbon and synergistically reducing through a'cracking-recessive growth 'mechanism; when C / N is high, a metabolism remodeling mode is started, effluent returns to the aerobic front end, and fundamental reduction and enhanced nitrogen and phosphorus removal are achieved through an energy decoupling mechanism. By means of mode-parameter-fungicide-path linkage control, the problem of mismatching of ASSR process mechanism and water quality is solved, and optimal distribution of carbon flow / electron flow and efficient sludge reduction are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sewage treatment, in particular to an intelligent control system and method for activated sludge process, and specifically to a carbon-to-nitrogen ratio adaptive side-stream sewage treatment system and sludge reduction method. BACKGROUND

[0002] Anaerobic side-stream reactor (ASSR) technology is an effective means to achieve in-situ sludge reduction in wastewater treatment plants. However, the existing technology has significant defects: using a single, fixed operation mode and reflux path, unable to respond to changes in influent water quality. Leading to insufficient carbon source under low C / N ratio, low efficiency of nitrogen and phosphorus removal; high sludge yield under high C / N ratio, and easy to cause sludge bulking. The core lies in the failure to precisely match the different reduction mechanisms of ASSR (hydrolysis acidification and metabolic remodeling) with the influent water quality (C / N ratio), and optimize its reflux path to achieve optimal allocation of carbon flow.

[0003] The treatment process for wastewater with different carbon-to-nitrogen ratios generally includes AAO process and A / O process. These traditional processes have significant defects when treating wastewater with large fluctuations in carbon-to-nitrogen ratio (C / N), mainly reflected in the following points:

[0004] First, poor adaptability of carbon-to-nitrogen ratio: low C / N (C / N < 5) wastewater requires external carbon addition, increasing operating costs; high C / N (C / N > 5) easily causes sludge bulking, poor system stability;

[0005] Second, low sludge reduction efficiency: traditional processes relying on endogenous respiration have a reduction rate of less than 30%, and functional bacteria are prone to inactivation;

[0006] Third, single function of side-stream unit: existing side-stream reactors are mostly used for sludge concentration or methanation, and do not form a synergistic control network with the main stream process;

[0007] Fourth, temperature sensitivity: low temperature environment inhibits microbial activity, high temperature may cause non-specific lysis, and seasonal fluctuations exacerbate control difficulty. SUMMARY

[0008] In order to solve the above technical problems, the application provides a dynamic synergistic regulation system, which solves the coupling problem of C / N fluctuation and temperature influence through the hydrolysis acidification-bacterial population screening double-function switching of a side stream reactor, targeted addition of bacterial agents, optimization of a reflux path and a low-temperature heating device. Under low-temperature conditions, the side stream reactor starts the heating device, strengthens the hydrolysis efficiency for low C / N and maintains the stability of bacterial population enrichment for high C / N, and realizes stable operation throughout the year. Through dynamic parameter regulation of the side stream reactor, targeted domestication and addition of functional bacterial population and optimization of the reflux path, the wide-spectrum adaptability treatment of C / N<4.5, 4.5≤C / N≤6 and C / N>6 is realized, and the pollutant removal efficiency and sludge reduction rate are simultaneously improved, which is suitable for municipal sewage, food wastewater, chemical wastewater and other high / low carbon-nitrogen ratio scenes.

[0009] The object of the application can be achieved by the following technical solutions:

[0010] In a first aspect, the application provides a carbon-nitrogen ratio adaptive side stream sewage treatment system, comprising:

[0011] a main stream reactor, a side stream anaerobic reactor (ASSR), an online monitoring unit, an intelligent control unit, a reflux path switching device and a bacterial agent targeted addition system;

[0012] The main stream reactor comprises an anaerobic zone, an anoxic zone and an aerobic zone, or adopts a main stream A / O reactor comprising a series-connected anaerobic section and aerobic section, and integrates a DO controller;

[0013] The side stream anaerobic reactor is equipped with HRT (hydraulic retention time) or SRT (sludge retention time), temperature, pH dynamic adjustment devices and a stirring unit, and is connected with the main stream reactor through a sludge reflux pump;

[0014] The online monitoring unit is used for real-time detection of influent COD and TN concentration and calculation of C / N, or integrates an online C / N detector;

[0015] The reflux path switching device contains controllable valves and corresponding conveying pipelines, and selectively returns the effluent of the side stream anaerobic reactor to the front end of the anaerobic zone or the aerobic zone of the main stream reactor;

[0016] The bacterial agent targeted addition system comprises a freeze-dried bacterial agent library, enzymes and a composite protective agent;

[0017] The intelligent control unit is configured to: according to the influent C / N detected by the online monitoring unit, control the side stream anaerobic reactor to switch between at least two operating modes, control the operating parameters of the side stream anaerobic reactor, control the bacterial agent targeted addition system to selectively add bacterial agents and / or enzymes, and control the reflux path switching device to selectively return the effluent of the side stream anaerobic reactor to the anaerobic zone or the aerobic zone of the main stream reactor.

[0018] Further, the bacterial agent is protected by a composite protective agent, and the active period of normal temperature preservation is ≥12 months; the freeze-dried bacterial agent bank comprises an internal carbon source metabolizing bacteria; the internal carbon source metabolizing bacteria is Candidatus Accumulibacter; the composite protective agent is composed of trehalose and nano kaolin at a mass ratio of 1:2; and the enzyme comprises protease and glycosidase.

[0019] Further, the operation mode comprises:

[0020] The latent growth mode is started when the influent C / N is less than 4.5, the side-stream anaerobic reactor is controlled to operate at the first set of parameters, the bacterial agent targeted dosing system is controlled to add the enzyme to the side-stream anaerobic reactor, and the effluent of the side-stream anaerobic reactor (ASSR) is controlled to be backflowed to the anaerobic zone of the main-stream reactor.

[0021] The metabolic remodeling mode is started when the influent C / N is greater than 6, the side-stream anaerobic reactor is controlled to operate at the second set of parameters, the bacterial agent targeted dosing system is controlled to add the internal carbon source metabolizing bacteria to the side-stream anaerobic reactor, and the effluent of the side-stream anaerobic reactor (ASSR) is controlled to be backflowed to the aerobic zone of the main-stream reactor.

[0022] The energy-saving mode is started when the influent C / N is between 4.5 and 6. For the energy-saving conservative mode, in this interval, the system defaults to the mild version of the latent growth mode. A shorter HRT (such as 6-8h) is adopted, but no high-temperature heating (maintaining normal temperature or a small increase in temperature to 30-35℃) is performed, and the pH is allowed to develop naturally (usually between 6.5 and 7.0). Under this C / N, the carbon source is not sufficient, but it is usually the main problem of most municipal wastewater in China. The mild short-time ASSR can produce appropriate VFA to assist in denitrification and phosphorus removal, and its latent growth effect can also bring certain reduction effect. Avoiding high-temperature heating can greatly reduce energy consumption, making the economy optimal in this interval. This is a robust and energy-saving strategy.

[0023] For trend prediction switching, the intelligent control unit not only monitors the instantaneous C / N value, but also analyzes its trend (such as the rising or falling rate in the past 2 hours). If the C / N value is rapidly increasing and approaching the second threshold, the parameters gradually approach those of the metabolic remodeling mode in advance; if the C / N value is rapidly decreasing and approaching the first threshold, the parameters approach those of the latent growth mode in advance. This can make the system switching more smooth, reduce mode oscillation caused by water quality fluctuations, and improve system stability.

[0024] Further, the first group of parameters comprises: hydraulic retention time (HRT) 4-12 hours, temperature 50-60 DEG C, pH 5.0-6.0; and the second group of parameters comprises: sludge retention time (SRT) 5-15 days, temperature 25-35 DEG C, pH 7.0-7.8.

[0025] Further, the intelligent control unit is further configured to: when the ambient temperature is less than 15 DEG C, start the warming device of the side-stream anaerobic reactor, and raise the temperature to 50-60 DEG C in the cryptic growth mode and maintain 25-35 DEG C in the metabolic remodeling mode.

[0026] Further, the intelligent control unit is further configured to: in the cryptic growth mode, adjust the DO of the aerobic section in the main-stream reactor to 0.1-0.5 mg / L, inhibit the proliferation of heterotrophic bacteria, and promote the dominance of amino acid metabolizing bacteria; and in the metabolic remodeling mode, adjust the DO of the anaerobic section in the main-stream reactor to 0.1-0.3 mg / L, and adjust the DO of the aerobic section to 1.5-3.0 mg / L, to strengthen the oxidation of internal carbon source and the coupling of denitrification.

[0027] In a second aspect, the present application provides a method for sludge reduction by using the above system, comprising the following steps:

[0028] (1) Real-time monitoring of influent water quality by the online monitoring unit, and calculating the carbon C / N;

[0029] (2) If the C / N is lower than the first threshold value, the side-stream anaerobic reactor is controlled to operate in the cryptic growth mode, the enzyme and / or amino acid metabolizing bacteria are added to the side-stream anaerobic reactor by the bacteria agent targeted addition system, and the effluent of the side-stream anaerobic reactor is backflowed to the anaerobic zone of the main-stream reactor;

[0030] The short-time ASSR (cryptic growth mode) reduction mechanism is as follows:

[0031] The core of this mode is "cell lysis (Lysis) + cryptic growth (Cryptic Growth)", and its essence is "carbon source recycling".

[0032] Side-stream lysis (Lysis): In the side-stream reactor, short HRT (4-12 h) and high temperature (50-60 DEG C) and acidic (pH 5.0-6.0) environment create excellent hydrolysis and acidification conditions. High temperature can effectively destroy the sludge floc structure, and crack the microbial cell wall and cell membrane. The acidic environment strongly inhibits the activity of methanogens consuming VFA, and activates the activity of hydrolytic enzymes and acidifying bacteria. As a result, a large number of microbial cells are lysed, and cell contents (proteins, polysaccharides, lipids, nucleic acids, etc.) and extracellular polymeric substances (EPS) are released into the water.

[0033] Side-stream hydrolysis & acidogenesis: macromolecular organic matters released are degraded into small molecules (such as amino acids, monosaccharides, long-chain fatty acids) by hydrolytic enzymes (proteases, glycosidases can be added in the present application to strengthen this process). These small molecules are further utilized by fermentative and acidogenic bacteria, and the end products of metabolism are mainly volatile fatty acids (VFA, such as acetic acid, propionic acid) and a small amount of alcohol, ketone, H2 and CO2.

[0034] Main-stream cryptic growth: the side-stream mixed liquor rich in VFA returns to the anaerobic zone of the main-stream reactor. VFA, as a high-quality carbon source, is preferentially utilized by PAOs and denitrifying bacteria, significantly strengthening the efficiency of biological phosphorus removal and denitrification (solving the core contradiction of low C / N water). A part of the unutilized lysed products and VFA are used as substrates by other heterotrophic bacteria in the aerobic zone for the synthesis of new cell material, and this process is called "cryptic growth". In addition, the addition of ASSR strengthens the hydrolysis and lysis of the main-stream sludge, further strengthening the sludge reduction effect brought by cryptic growth. The essence of reduction is that cryptic growth is a secondary synthesis process with extremely low energy efficiency. Cell lysis has caused energy loss, and secondary synthesis also has energy loss. Ultimately, more total COD (energy) in the influent is consumed to produce heat and CO2 rather than to synthesize new biomass, thereby achieving sludge reduction. Reduction is a "byproduct" of the carbon source recovery process.

[0035] (3) If the C / N is higher than the second threshold value, the side-stream anaerobic reactor is controlled to operate in the metabolic remodeling mode, the bacteria agent targeted dosing system adds internal carbon source metabolizing bacteria to the side-stream anaerobic reactor, and the effluent of the side-stream anaerobic reactor is backflowed to the aerobic zone of the main-stream reactor.

[0036] The reduction mechanism of the metabolic remodeling mode is as follows:

[0037] This environment imposes strong ecological selection pressure, enriches PHA storage bacteria (such as PAOs / GAOs), and promotes the secretion of laccase, peroxidase, etc. by triggering oxidative stress (up-regulation of oxyR / soxR genes), catalyzing the synthesis of fulvic acid and other electron shuttles. The core of this mode of reduction is "metabolic selection pressure + energy uncoupling (Energy Uncoupling)". The energy allocation strategy of microbial community is fundamentally remodeled: PHA is synthesized in anaerobic period; the energy generated by PHA oxidation in aerobic period is mostly used to maintain metabolism and phosphorus removal / denitrification, and part of the electrons are transferred extracellularly through fulvic acid, bypassing the coupled phosphorylation of ATP production, causing energy to be lost in the form of heat. The total amount of ATP generated per unit of influent COD is reduced, and the proportion used for biosynthesis is greatly reduced, reducing sludge production from the source. Reduction is the direct purpose, and its essence is the "energy economy" mode revolution of microbial society. To provide an instant environment for the aerobic oxidation of intracellular PHA in the functional bacterial population, energy is used for excess phosphorus uptake; the fulvic acid in EPS works efficiently at the aerobic-anoxic interface, directly transferring electrons from the PHA oxidation process to nitrate (denitrification), significantly enhancing the efficiency of simultaneous nitrification and denitrification (SND) and denitrifying phosphorus removal.

[0038] Returning ASSR sludge to the aerobic tank is the key to activating the entire process synergy: it significantly enriches the electrically active components such as fulvic acid in EPS (fluorescence intensity increases by ~275%) by triggering a severe oxidative stress response, creating a highly efficient extracellular electron shuttle network; this allows the intracellular stored PHA electrons to be efficiently and directionally transferred to the functional bacterial population, thereby achieving a significant reduction (>50%) in sludge production while driving a significant increase in denitrification and phosphorus removal rates (about 15% and 10% higher than traditional processes in TN and TP removal rates, respectively), ultimately achieving the dual goals of sludge reduction and deep pollutant removal.

[0039] The core of this mode is "metabolic selection pressure + energy uncoupling (Energy Uncoupling)", and its essence is "metabolic revolution".

[0040] Ecological Selection Pressure: Placing sludge in a long SRT_SS (5-15 days) and strictly anaerobic environment is a strong ecological selection pressure. Ordinary heterotrophic bacteria with short generation time and rapid growth cannot compete in this "starvation" environment and are gradually eliminated. A group of bacteria with special metabolic strategies, PHA storage bacteria (such as polyphosphorus bacteria PAOs and polysaccharide bacteria GAOs), are enriched as the dominant bacterial population. Their metabolic mode is the "champion" of "feast-famine alternation".

[0041] Metabolic remodeling: anaerobic phase ("feast" phase): these populations can quickly absorb simple carbon sources such as VFAs in the influent, but do not directly use them for proliferation. Instead, they synthesize PHAs (such as PHB, PHV) from ATP at the cost of energy storage in the body. This is an "investment" process that consumes energy storage carbon sources. Aerobic / anoxic phase ("starvation" phase): they oxidize and decompose the PHA stored in the body, producing energy (ATP) and reducing power (NADH). Used for maintenance metabolism. Used for absorbing phosphorus (for PAOs) or reducing nitrate (for denitrifying PAOs). Only a small part of the energy is used to synthesize new cell material.

[0042] Energy decoupling and reduction essence: in traditional metabolism, the flow of electrons (e - ) is transmitted from the substrate through the respiratory chain, coupled to produce ATP, which is mainly used for biosynthesis (proliferation). In the metabolism of PHA storage bacteria, the flow of energy (ATP and electrons) is reprogrammed and decoupled: a part of ATP is "wasted" in the synthesis of PHA in the anaerobic phase (energy investment). A part of the electrons is transmitted through the decoupled respiratory chain (such as being bypassed by some coupling sites by fumarate and other electron shuttles) in the aerobic phase, and the energy is dissipated in the form of heat. Finally, the total amount of ATP produced per unit mass of influent COD is reduced, and the proportion of ATP used for biosynthesis is greatly reduced. Reduction essence: the overall metabolic phenotype of the microbial community changes from "maximizing proliferation" to "prioritizing storage and maintenance", cutting off the root cause of sludge production from the source, and achieving fundamental and high-efficiency sludge reduction.

[0043] (4) If the first threshold ≤ C / N ≤ second threshold, then start the energy-saving mode, use gentle parameters (HRT = 6-8 hours, 30-35℃), and return to the anaerobic zone.

[0044] The water quality in this interval is in a critical state of "carbon source not sufficient but not excessive". Simple "maintain the current mode" may lead to mode oscillation, and "mixed mode" lacks definition. The most intelligent strategy is to introduce a third mode - energy-saving conservative mode, or use fuzzy control based on trend prediction for switching.

[0045] For the energy-saving conservative mode, the system defaults to a mild version of the implicit growth mode in this interval. A shorter HRT (such as 6-8h) is adopted, but high-temperature heating is not performed (maintain normal temperature or slightly increase to 30-35℃), and the pH is allowed to develop naturally (usually at 6.5-7.0). Under this C / N, the carbon source is not sufficient, but it is still the main problem of most municipal wastewater in China. Using a mild short-time ASSR, appropriate VFA can be produced to assist in denitrification and phosphorus removal, and the implicit growth effect of the ASSR itself can also bring a certain amount of reduction effect. Avoiding the opening of high-temperature heating can greatly reduce energy consumption, making the economy optimal in this interval. This is a robust and energy-saving strategy.

[0046] For trend prediction switching, the intelligent control unit not only monitors the instantaneous C / N value, but also analyzes its trend (such as the rising or falling rate in the past 2 hours). If the C / N value is rapidly increasing and approaching the second threshold, the parameters of the metabolic remodeling mode are gradually approached in advance; if the C / N value is rapidly decreasing and approaching the first threshold, the parameters of the carbon source supplement mode are approached. This can make the system switching more smooth, reduce mode oscillation caused by water quality fluctuations, and improve system stability. However, this requires more complex algorithms and more reliable water quality prediction models.

[0047] Therefore, if the first threshold ≤ C / N ≤ second threshold, the intelligent control unit starts the energy-saving conservative mode. Control the ASSR to run at a medium hydraulic retention time (HRT = 6-8 hours), stop heating (maintain ambient temperature or slightly increase to 30-35℃, and do not actively control the pH. In this mode, the ASSR maintains moderate hydrolysis and acidification function at lower energy consumption, and cooperatively realizes implicit growth and sludge reduction.

[0048] Further, the first threshold has a value range of less than 4.5, and the second threshold has a value range of greater than 6.

[0049] Further, the method further comprises the steps of: when the ambient temperature is less than 15℃, starting the warming device of the side-stream anaerobic reactor, and increasing the temperature to 50-60℃ in the implicit growth mode and maintaining 25-35℃ in the metabolic remodeling mode.

[0050] Further, the method further comprises the steps of: in the implicit growth mode, controlling the DO of the aerobic section of the main-stream reactor to be 0.1-0.5 mg / L to inhibit the proliferation of heterotrophic bacteria and promote the dominance of amino acid metabolizing bacteria; and in the metabolic remodeling mode, adjusting the DO of the anaerobic section of the main-stream reactor to be 0.1-0.3 mg / L and the DO of the aerobic section to be 1.5-3.0 mg / L to strengthen the oxidation of internal carbon sources and denitrification coupling.

[0051] The sludge reduction principle of the present application is as follows:

[0052] The two mechanisms of ASSR are essentially different, and need to match different reflux paths and bacterial agents to maximize efficiency.

[0053] The recessive growth mode (short time, high temperature, acidification, and addition of enzyme / amino acid metabolizing bacteria): The reduction is derived from energy loss and recessive growth. The reflux to the anaerobic zone is to ensure that the product VFA is used most efficiently by PAOs, thereby achieving efficient phosphorus removal and reduction simultaneously. The addition of hydrolytic enzymes strengthens the lysis and hydrolysis process. In addition, it also speeds up the hydrolysis process of the main stream POM, further strengthening the hydrolysis of sludge, etc., achieving sludge lysis-recessive growth of the main stream process.

[0054] The metabolic remodeling mode (long time, medium temperature, slightly alkaline, and addition of internal carbon source metabolizing bacteria): The reduction is derived from energy diversion and decoupling. The reflux to the aerobic front end is to perfectly link the metabolic links of "PHA anaerobic synthesis" and "PHA aerobic oxidation". The addition of internal carbon source metabolizing bacteria (such as Candidatus Accumulibacter) strengthens the synthesis and storage capacity of PHA. The reflux of ASSR sludge to the aerobic tank is the key to activate the entire process synergistic effect: it triggers a severe oxidative stress response, significantly enriches the electrically active components such as fulvic acid in EPS (fluorescence intensity increases by about 275%), and constructs an efficient extracellular electron shuttle network; this enables the intracellular stored PHA electrons to be efficiently and directionally transmitted to the functional bacterial flora, thereby achieving a significant reduction (>50%) in sludge production while driving the denitrification and phosphorus removal rates to increase significantly (about 15% and 10% higher than traditional processes, respectively), and finally achieving the dual goals of sludge reduction and deep pollutant removal.

[0055] The present application realizes the optimal path allocation of "carbon flow" and "electron flow" through the intelligent linkage of "mode-parameter-bacterial agent-path", which is the key to synergistic effect.

[0056] The core of the present application is to realize the three-dimensional synergistic intelligent control of "mode-parameter-path", and accurately match the demands of two different reduction mechanisms for carbon flow path.

[0057] The recessive growth mode: The shortest carbon flow path of "lateral stream high-speed acid production-anaerobic zone direct utilization" is constructed to serve the "lysis-recessive growth" reduction mechanism. The addition of hydrolytic bacteria strengthens the lysis and hydrolysis process.

[0058] The metabolic remodeling mode: The efficient electron flow path of "lateral stream domesticated bacterial flora-aerobic zone oxidation / shuttle" is constructed to serve the "energy decoupling" reduction mechanism. The addition of internal carbon source metabolizing bacteria (such as Candidatus Accumulibacter) strengthens the synthesis and storage capacity of PHA.

[0059] The precise control of the reflux path is the key to opening up the "last mile" of the above strategy, ensuring that the intermediate product (VFA or PHA / humic acid) is consumed at the most suitable location with the highest efficiency, and globally optimizing the carbon, nitrogen, phosphorus, and energy metabolic network of the system.

[0060] The application can produce the following beneficial effects:

[0061] The application adopts multi-stage C / N regulation, adopts differentiated strategies according to the C / N range, realizes broad-spectrum adaptation, strengthens the core biological reaction in each mode through the bacteria agent adding system, realizes optimal distribution of carbon flow through reflux path switching, and strengthens hydrolysis or maintains bacterial population enrichment under low temperature conditions through the warming device for different C / N requirements. In the low C / N mode, the sludge reduction rate can be >30%, and the total nitrogen removal rate can be increased by more than 10%; in the high C / N mode, the sludge reduction rate can be >50%, and the total nitrogen and total phosphorus removal rates can be increased by more than 10%; the application adopts single-sided flow reactor multifunctional design to reduce construction and operation cost.

[0062] Specifically, the advantages of the application are as follows:

[0063] (1) Intelligent and precise control: for the first time, the influent C / N is used as the core control parameter to realize the intelligent switching of the ASSR "operation mode-process parameter-reflux path".

[0064] (2) Synergistic effect: through precise reflux path control, the effect is maximized, realizing sludge reduction and simultaneous nitrogen and phosphorus removal.

[0065] (3) Energy consumption optimization: through path optimization, the invalid consumption of carbon source and energy is avoided, and the system operation cost is further reduced through energy-saving mode.

[0066] (4) Broad-spectrum adaptability: through three modes, the influent range from extremely low to extremely high C / N is covered, and strong impact load resistance is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0067] Figure 1 It is a structural schematic diagram of the sewage treatment system of the application, wherein 1 is an anaerobic tank, 2 is an anoxic tank, 3 is an aerobic tank, 4 is a secondary sedimentation tank, and 5 is a side-stream anaerobic reactor (ASSR).

[0068] Figure 2 It is an intelligent control logic flow chart of the sewage treatment system of the application. DETAILED DESCRIPTION

[0069] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work are within the protection scope of the present application. In the following embodiments, the main stream reactor is taken as an example of A 2 O, but it is also applicable to A / O and other processes.

[0070] A carbon-nitrogen ratio adaptive side-stream sewage treatment system, as shown in Figure 1 , comprises:

[0071] A main stream A 2 O reactor, a side-stream anaerobic reactor (ASSR), an online water quality monitor, an intelligent control unit, a reflux path switching device and a bacterial agent targeted dosing system.

[0072] The ASSR is equipped with a stirrer, a heating rod, a pH probe and a control valve, and a sludge inlet and outlet valve, for adjusting HRT / SRT, temperature and pH.

[0073] The online monitoring unit detects the concentrations of influent COD and TN in real time and calculates C / N.

[0074] The reflux path switching device comprises two controllable electric valves and two pipelines, which can deliver the effluent of the ASSR to the front end of the main stream anaerobic zone or the front end of the aerobic zone.

[0075] The bacterial agent targeted dosing system comprises a storage tank, a metering pump and a dosing port, Candidatus Accumulibacter bacterial liquid concentrate, protease powder, glycosidase powder and trehalose-kaolin composite protective agent.

[0076] The intelligent control unit receives the C / N data of the online monitoring unit, and outputs instructions to control the parameters of the ASSR, the start-stop and dosage of the bacterial agent dosing system, the opening and closing of the reflux path valve and the DO set value of the main stream reactor, through the built-in fuzzy PID control algorithm. The intelligent control logic flow chart of the sewage treatment system of the present application is shown in Figure 2 .

[0077] Example 1: Treatment of low C / N municipal sewage in recessive growth mode

[0078] Influent C / N < 4.5, COD = 180 mg / L, TN = 60 mg / L. Ambient temperature 20℃.

[0079] The intelligent system starts the implicit growth mode: control the ASSR parameters as HRT = 6h, T = 55℃, pH = 5.5; control the inoculant system to add 0.2g / L protease and 0.5g / L Thauera freeze-dried powder into the ASSR; control the reflux path valve to reflux the ASSR effluent to the front end of the main stream anaerobic zone; control the main stream aerobic section DO = 0.2mg / L.

[0080] Results: The sludge yield is reduced to 0.10gVSS / gCOD (reduction rate 55%), the TN removal rate reaches 60%, and the TP removal rate reaches 80%.

[0081] Example 2: Metabolic remodeling mode for treating high C / N wastewater

[0082] The influent C / N is >6, COD = 500mg / L, and TN = 30mg / L. The environmental temperature is 25℃.

[0083] The intelligent system starts the metabolic remodeling mode: control the ASSR parameters as SRT = 8d, T = 30℃, pH = 7.5; control the inoculant system to add 10 7 CFU / mL Candidatus Accumulibacter concentrate; control the reflux path valve to reflux the ASSR effluent to the front end of the main stream aerobic zone; control the main stream anaerobic section DO = 0.1mg / L, and the aerobic section DO = 2.5mg / L.

[0084] Results: The sludge yield is reduced to 0.06gVSS / gCOD (reduction rate 70%), the TN removal rate reaches 95%, the TP removal rate reaches 90%, and there is no filamentous bacteria explosion.

[0085] Example 3: Treatment of low C / N sewage in low temperature environment

[0086] The influent C / N is <4.5, COD = 200mg / L, and TN = 65mg / L. The environmental temperature is 10℃.

[0087] The intelligent system detects the low temperature and starts the ASSR heat preservation device. The implicit growth mode is started: control the ASSR parameters as HRT = 8h, T = 58℃, pH = 5.8; control the inoculant system to add 0.3g / L protease into the ASSR; control the reflux path to the anaerobic zone; control the main stream aerobic section DO = 0.3mg / L.

[0088] Results: The sludge yield is reduced to 0.07gVSS / gCOD (reduction rate 68%), the TN removal rate reaches 65%, and the system runs stably.

[0089] Example 4: Metabolic of low C / N municipal wastewater

[0090] A 2 / O-ASSR and A2 A / O-ASSR and A / O sewage treatment process comparison, influent C / N < 4.5, COD = 120 mg / L, TN = 30 mg / L, TP = 3 mg / L; start metabolic remodeling mode, control ASSR parameters SRT = 6d, sludge exchange law is 15%, the effluent of side stream anaerobic reactor returns to the front end of the aerobic tank, sludge reduction rate is about 10%, total nitrogen removal rate is 75%; intelligent system starts the latent growth mode, control ASSR parameters HRT = 6-8h, sludge exchange law is 50%, replace the control reflux path valve to return the effluent of ASSR to the front end of the main stream anaerobic zone, sludge reduction rate is about 30%, total nitrogen removal rate is 85%, total nitrogen removal rate can be increased by more than 10%.

[0091] Example 5: Metabolic mode for treating high C / N sewage

[0092] A / O-ASSR and A / O sewage treatment process comparison, influent C / N < 4.5, COD = 120 mg / L, TN = 30 mg / L, TP = 3 mg / L; start metabolic remodeling mode, control ASSR parameters SRT = 6d, sludge exchange law is 15%, the effluent of side stream anaerobic reactor returns to the front end of the aerobic tank, sludge reduction rate is about 10%, total nitrogen removal rate is 75%; intelligent system starts the latent growth mode, control ASSR parameters HRT = 6-8h, sludge exchange law is 50%, replace the control reflux path valve to return the effluent of ASSR to the front end of the main stream anaerobic zone, sludge reduction rate is about 30%, total nitrogen removal rate is 85%, total nitrogen removal rate can be increased by more than 10%.

[0093] The above is a specific description of the preferred embodiment of the application, but the application is not limited to the described embodiments, and those skilled in the art can make various equivalent modifications or replacements without departing from the spirit of the application, and these equivalent modifications or replacements are all included in the scope defined by the claims of the present application.

Claims

1. A carbon to nitrogen ratio adaptive side stream sewage treatment system, characterized by, The application relates to a main stream reactor, a side stream anaerobic reactor, an online monitoring unit, an intelligent control unit, a reflux path switching device and a bacterial agent targeted adding system. The main stream reactor comprises an anaerobic zone, an anoxic zone and an aerobic zone, or adopts a main stream A / O reactor comprising an anaerobic section and an aerobic section connected in series, and is integrated with a DO controller. The side stream anaerobic reactor is equipped with HRT or SRT, temperature, pH dynamic adjusting devices and a stirring unit, and is connected with the main stream reactor through a sludge reflux pump. The online monitoring unit is used for detecting the concentrations of influent COD and TN and calculating C / N in real time, or is integrated with an online C / N detector. The reflux path switching device comprises controllable valves and corresponding conveying pipelines, and selectively returns effluent of the side stream anaerobic reactor to the front end of the anaerobic zone or the aerobic zone of the main stream reactor. The bacterial agent targeted adding system comprises a freeze-dried bacterial agent library, enzymes and a composite protective agent. The intelligent control unit is configured to control the side stream anaerobic reactor to switch between at least two operation modes according to the influent C / N detected by the online monitoring unit, control operation parameters of the side stream anaerobic reactor, control the bacterial agent targeted adding system to selectively add bacterial agents and / or enzymes, and control the reflux path switching device to selectively return effluent of the side stream anaerobic reactor to the front end of the anaerobic zone or the front end of the aerobic zone of the main stream reactor. The bacterial agent is protected by the composite protective agent, and the activity period of the bacterial agent is greater than or equal to 12 months at room temperature; the freeze-dried bacterial agent library comprises internal carbon source metabolizing bacteria, and the internal carbon source metabolizing bacteria are mainly Candidatus Accumulibacter; the composite protective agent is composed of trehalose and nano-scale kaolin at a mass ratio of 1:2; and the enzymes include protease and glycosidase.

2. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 1, wherein, The at least two operation modes comprise:

3. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 2, wherein, a latent growth mode, which is started when the influent C / N is less than a first threshold value, controls the side stream anaerobic reactor to operate at a first set of parameters, controls the bacterial agent targeted adding system to add enzymes to the side stream anaerobic reactor, and controls effluent of the side stream anaerobic reactor to return to the anaerobic zone of the main stream reactor; a metabolic remodeling mode, which is started when the influent C / N is greater than a second threshold value, controls the side stream anaerobic reactor to operate at a second set of parameters, controls the bacterial agent targeted adding system to add internal carbon source metabolizing bacteria to the side stream anaerobic reactor, and controls effluent of the side stream anaerobic reactor to return to the aerobic zone of the main stream reactor; an energy-saving conservative mode, which is started when the influent C / N is between the first threshold value and the second threshold value, defaults to a mild version of the latent growth mode, controls the HRT to be 6-8 hours, maintains room temperature or warms up to 30-35 DEG C, controls the pH to be naturally developed to 6.5-7.0, and controls effluent of the side stream anaerobic reactor to return to the anaerobic zone of the main stream reactor. The first set of parameters of the side stream anaerobic reactor comprises a hydraulic retention time of 4-12 hours, a temperature of 50-60 DEG C, a pH of 5.0-6.0 and a sludge exchange rate of 50-100%; and the second set of parameters comprises a sludge retention time of 5-15 days, a temperature of 25-35 DEG C, a pH of 7.0-7.8 and a sludge exchange rate of 10-50%.

4. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 3, wherein, ​ 5. A carbon to nitrogen ratio self-adapting lateral flow sewage treatment system according to claim 3, wherein, The intelligent control unit is further configured to start the warming device of the side-stream anaerobic reactor when the ambient temperature is less than 15 DEG C, and to raise the temperature to 50-60 DEG C in the cryptic growth mode and to maintain 25-35 DEG C in the metabolic remodeling mode.

6. The carbon-to-nitrogen ratio adaptive lateral flow sewage treatment system according to claim 3, wherein, The intelligent control unit is further configured to adjust the DO of the aerobic section of the main-stream reactor to 0.1-0.5 mg / L in the cryptic growth mode, and to adjust the DO of the anaerobic section of the main-stream reactor to 0.1-0.3 mg / L and the DO of the aerobic section to 1.5-3.0 mg / L in the metabolic remodeling mode.

7. A method for sludge reduction using the system according to any one of claims 3 to 6, characterized in that, The method comprises the following steps: (1) monitoring the influent water quality in real time through the online monitoring unit and calculating the carbon C / N; (2) if the C / N is lower than a first threshold value, controlling the side-stream anaerobic reactor to operate in the cryptic growth mode, controlling the bacteria agent targeted dosing system to add enzyme and / or amino acid metabolizing bacteria to the side-stream anaerobic reactor, and returning the effluent of the side-stream anaerobic reactor to the anaerobic zone of the main-stream reactor; (3) if the C / N is higher than a second threshold value, controlling the side-stream anaerobic reactor to operate in the metabolic remodeling mode, controlling the bacteria agent targeted dosing system to add internal carbon source metabolizing bacteria to the side-stream anaerobic reactor, and returning the effluent of the side-stream anaerobic reactor to the aerobic zone of the main-stream reactor; (4) when the influent C / N is between the first threshold value and the second threshold value, starting the system, and the system defaults to the mild version of the cryptic growth mode, controls the HRT to be 6-8 hours, maintains the normal temperature or raises the temperature to 30-35 DEG C, and controls the pH to be naturally developed to 6.5-7.0, and controls the effluent of the side-stream anaerobic reactor to be returned to the anaerobic zone of the main-stream reactor.

8. A method of sludge reduction according to claim 7, characterised in that, The first threshold value is less than 4.5, and the second threshold value is greater than 6.

9. A method of sludge reduction according to claim 7, characterised in that, The method further comprises the steps of starting the warming device of the side-stream anaerobic reactor when the ambient temperature is less than 15 DEG C, and raising the temperature to 50-60 DEG C in the cryptic growth mode and maintaining 25-35 DEG C in the metabolic remodeling mode.

10. A method of sludge reduction according to claim 7, characterised in that, The method further comprises the steps of controlling the DO of the aerobic section of the main-stream reactor to be 0.1-0.5 mg / L in the cryptic growth mode, and controlling the DO of the anaerobic section of the main-stream reactor to be 0.1-0.3 mg / L and the DO of the aerobic section to be 1.5-3.0 mg / L in the metabolic remodeling mode.

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