Filler layout optimization method of biological predation sewage treatment reaction device

Abstract

The invention discloses a filler layout optimization method of a biological predation sewage treatment reaction device. By establishing an optimization model of the energy dissipation efficiency E, the biocenosis diversity D and the pollutant removal rate R of the microbial food web in the biological predation sludge reduction reactor, the biomass of each nutritional level of the microbial food web under the optimal condition of the three is determined, and the distribution amount of the filler in the biological sewage treatment reactor is calculated. The filler dosage set according to the calculation result improves the pollutant removal efficiency and the sludge reduction effect, improves the impact load resistance of the multi-stage microbial food web, enables the impacted microbial food web to recover to the optimized stable state, and finally improves the stability and efficiency of the whole biological predation sewage treatment system. According to the method disclosed by the invention, the problems of waste caused by excessive arrangement of the filler and low efficiency, instability and the like of the system caused by insufficient arrangement are avoided, and the pollutant removal efficiency, the sludge reduction effect and the operation stability of the biological predation sewage treatment system are remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental engineering, and relates to a filler layout optimization method for a biological predation sewage treatment reaction device, and in particular to an innovation of a scientific layout method of high-performance fillers in a sewage biological treatment process. Background Art

[0002] Biological treatment is the most commonly used technology in sewage treatment plants around the world. However, traditional sewage biological treatment often produces a large amount of residual sludge. Therefore, it is urgent to develop green and low-carbon sludge in-situ reduction technology.

[0003] Among various technologies that enhance the efficiency of sludge reduction based on enhanced microbial metabolism, biological predation sludge reduction technology has attracted widespread attention due to its high sludge reduction rate and low operating cost. Based on the principle of biological predation, researchers have proposed several types of biological treatment reactors, including worm reactors, food chain reactors, integrated fixed biofilms, and biological contact oxidation processes. The main purpose is to construct a microbial food chain (web) in the sewage biological treatment system, and to extend the food chain in the sewage treatment system by regulating process parameters such as hydraulic retention time and aeration volume, thereby improving biological predation and energy dissipation efficiency and enhancing sludge reduction effects.

[0004] However, to date, existing literature reports have failed to fully describe the structure and function of the microbial food web in sewage treatment systems. There is still a gap in the research on the energy transfer efficiency of microbial food webs in sewage. The transfer efficiency of different microbial food chains in sewage treatment systems has not been quantified. There is also a lack of technical methods to regulate the microbial food chain (web) in sewage systems and improve the energy transfer efficiency of sewage microbial food webs.

[0005] As a carrier for the attachment of biological communities and biofilms in sewage treatment reactors, fillers play an important role in improving the metabolic efficiency of microorganisms and adjusting the structure and function of microbial communities. By modifying the fillers, the specific surface area of ​​the fillers can be increased, and the microbial load can be increased; increasing the amount of fillers, the number of reactor steps, or extending the hydraulic retention time can extend the food chain, thereby improving the sludge reduction effect. Existing literature has reported on the effects of filler layout forms (curtain-shaped, vortex-shaped, suspended, etc.) and types (nylon fiber, graphene fiber, activated carbon, polyurethane sponge, etc.) on sewage treatment, sludge reduction effect, and microbial activity. The document "Study on the Pollutant Removal Efficiency and Microbial Characteristics of MPR Composite Fillers" reports the pollutant removal effect and sludge reduction performance of a micro-pressure internal circulation multi-biological phase reactor (MPR) with different filler carriers (spherical polypropylene hollow spheres, cylindrical high-density polyethylene K-type, and square polyurethane porous foam filler carriers) added in the same proportion (10%). By detecting the characteristics of activated sludge and biofilm and the structure of microbial flora, the pollutant removal and sludge reduction effects were verified, and the optimal filler type of the MPR composite filler system was obtained, but the effect of the filler on protozoa and sludge reduction was not considered. The document "Study on the Enhancement of Fillers on Sludge In-situ Sidestream Reduction Process" analyzes the effects of fillers and filler filling rate levels of ultrasonically coupled cylindrical polyethylene carrier elements on pollutant removal, sludge reduction effect and membrane fouling, and explores its microbial population structure and sludge reduction functional flora, but does not consider the effect of fillers on protozoa and their stability. The document "Study on Sludge Reduction Method Based on Earthworm Biological Predation in A / O Process" reported the effects of combined fillers and three-dimensional fiber fillers on earthworm attachment and growth and their sludge reduction effects, but did not consider the stability of earthworm populations. The document "Pilot Study on Filler Filling Rate in Moving Bed Biofilm Reactor (MBBR) Process" used experimental methods to test the effects of different carrier filling rates on the removal rates of organic matter and ammonia nitrogen in sewage, and concluded that 35% of suspended fillers were the optimal dosage. In summary, the existing reports have mostly judged the amount of fillers based on experience, or only used a small number of experiments for comparative studies, which can easily cause problems of overfilling or insufficient filling rate, and mainly considered the role of microbial attachment on pollutant purification and sludge reduction, and failed to provide a scientific optimization filler layout design calculation method, which is not suitable for biological predation sewage treatment systems, and it is difficult to truly achieve the efficient performance of fillers, the stability of sewage treatment systems, and the improvement of sludge reduction effects.

[0006] In order to achieve the optimal configuration of packing in biological predation wastewater treatment reactors, it is urgent to develop a packing layout calculation method that comprehensively considers pollutant degradation efficiency, sludge reduction mechanism, biological community stability, and microbial food web (chain) energy dissipation and transfer efficiency. Summary of the invention

[0007] The present invention proposes a method for optimizing the layout of fillers in a biological predation sewage treatment reactor. By establishing an optimization model of the energy dissipation efficiency E of the microbial food web, the diversity D of the biological community and the pollutant removal rate R in the biological predation sludge reduction reactor, the biomass of each trophic level of the microbial food web under the optimal conditions of the three is determined, and the layout amount of fillers in the sewage biological treatment reactor is calculated. The amount of fillers arranged according to the calculation results can improve the impact load resistance of the multi-level microbial food web while improving the pollutant removal efficiency and the sludge reduction effect, so that the impacted microbial food web can be restored to the optimized stable state, and finally the stability and efficiency of the entire biological predation sewage treatment system can be improved.

[0008] The technical solution of the present invention:

[0009] A method for optimizing the layout of fillers in a biological predator sewage treatment reaction device, comprising the following steps:

[0010] Step 1: Establish a basic model for optimizing the layout of fillers in biological predation wastewater treatment reactors;

[0011] f(R,E,D)=R×E×D (1)

[0012] Among them, R is the removal rate of pollutants in the biological predator sewage treatment reactor, E is the energy dissipation efficiency of the microbial food web, and D is the diversity of the biological community in the system; the maximum value of each factor in the basic model of the optimization of the filler layout of the biological predator sewage treatment reactor is taken to obtain the optimization target;

[0013] Step 2: Calculate the pollutant removal rate R;

[0014] The pollutant removal rate R is completed by various organisms (including bacteria, protozoa, metazoa and other major groups) in the biological predation sewage treatment reactor, and is characterized by the carbon removal rate. For a stable sewage treatment system, the pollutant removal rate of various organisms is closely related to their carbon source utilization rate r. The removal rate of carbon in the water body can be estimated by the biomass B of each trophic level and the carbon source utilization rate r, that is:

[0015]

[0016] TOC is the total organic carbon content of the influent in the biological predation wastewater treatment reactor. The carbon source utilization rate of bacteria is related to the type of filler. Fillers with conductivity and enhanced electron transfer ability can improve the carbon source utilization rate of bacteria. 细菌 ,pass 18 OH 2 O culture experiments were performed to determine the carbon source utilization of protozoa and metazoa. 14 C isotope labeling method;

[0017] The biomass of bacteria can be measured by plate counting or DNA content determination (each bacterial cell contains an average of about 8.4×10 -5 ng) to obtain the species number S, which is multiplied by the weight of a single bacterium (approximately 0.001 ng).

[0018] The biomass of protozoa and metazoa can be obtained by multiplying the number of species S, the individual density ρ and the individual volume V, that is:

[0019] B=S×ρ×V (3)

[0020] For protozoa and metazoa, due to their high water content, the density of individual organisms can be approximately considered to be equal to the density of the water body (that is, the density is assumed to be ρ = 1 g / mL). The species number S and individual volume V are obtained by ultra-high power microscopy after standard sampling.

[0021] Step 3: Calculate the energy dissipation efficiency E of the microbial food web;

[0022] The energy dissipation efficiency E of the microbial food web is composed of the sum of the dissipation efficiencies of food chains of different lengths:

[0023] E=E 2 +E 3 +E 4 +E 5 (4)

[0024] Among them, E 2 、E 3 、E 4 、E 5 Respectively represent the energy dissipation efficiency of the food chain composed of the second, third, fourth and fifth trophic levels; limited by the nutrient and environmental conditions of the sewage treatment system, the trophic level of the microbial food web in the sewage treatment system generally does not exceed level 5, such as bacteria → rotifers → cladocerans → copepods → insects. The energy dissipation efficiency E of two adjacent trophic levels can be calculated by the ratio of the biomass difference of the two trophic levels to the biomass of the lower trophic level. For a food chain containing n trophic levels, its energy dissipation efficiency is expressed as:

[0025]

[0026] Among them, B 1 is the biomass of the first trophic level (bacteria), that is, B 细菌 . B n is the biomass of the nth trophic level (n = 2, 3, 4, 5); limited by the energy transfer efficiency of the food chain (e, generally between 5% and 63%, B n =B n-1×e), the longer the food chain is, the lower the energy transfer efficiency is and the higher the dissipation efficiency E is. Therefore, extending the food chain can increase energy dissipation and improve the effect of biological predation on sludge reduction.

[0027] Step 4: Calculate the diversity D of the microbial food web community;

[0028] The diversity of biological communities in biological predators wastewater treatment systems was calculated using the Shannon index (H):

[0029]

[0030] Among them, S is the total number of species in the community, P i is the proportion of the i-th species to all species.

[0031] The Shannon index H of the biological community was standardized, and the calculated results were standardized in the range of (0,1], which was used as the biological community diversity D in the basic model for the optimization of the layout of the filler in the biological predator sewage treatment reactor.

[0032] Step 5: Perform multi-objective calculations on the basic model for optimizing the layout of the filler in the biological predator wastewater treatment reactor to obtain the optimized biomass of each trophic level; in the biological predator wastewater treatment reactor, as the pollutant concentration decreases, the pollutant removal rate increases, the microbial food web capacity dissipation efficiency increases, and the sludge reduction increases; within a certain range of pollutant concentrations, the diversity of the biological community is the highest, at this time the food chain is long, and the microbial food web energy dissipation efficiency is high; based on the above relationship, the above formulas are combined to calculate a set or a certain range of B 细菌,优化 , B 原生动物,优化 , B 后生动物,优化 Make R, E, and D in the biological predation sewage treatment reactor within the optimal range.

[0033] Step 6: Biomass B obtained based on the optimization results 细菌,优化 Calculate the packing layout parameters; for a given packing, if its specific surface area M is known, the packing addition rate T can be calculated by the following formula:

[0034] Bacteria, optimization = α × M × T (6)

[0035] Where α is the density of bacteria in the biofilm on the filler, g / m 2 ; M is the specific surface area of ​​the filler, m 2 / m 3 ; T is the filler addition rate = filler volume / filler area volume;

[0036] Based on the calculated specific surface area and addition rate of the filler, combined with the type and inherent properties of the filler, the weight or volume of the filler is inferred to obtain the filler layout amount.

[0037] Further combined with the energy transfer efficiency e of the food chain, the relationship between the biomass of protozoa and the specific surface area and addition rate of the filler is established. For a given filler, if its specific surface area is known, its addition rate can be determined by reverse calculation.

[0038] The beneficial effects of the present invention are as follows: the present invention establishes an optimization model of microbial food web energy dissipation efficiency E, biological community diversity D and pollutant removal rate R according to the characteristics of the biological predation sewage treatment system, and uses biomass B as a medium to establish the relationship between the filler specific surface area and addition rate and E, H, and R. The optimal filler layout conditions are obtained through precise calculation, thereby improving the utilization rate of the filler, giving full play to the role of the filler in biofilm attachment, strengthening microbial electron transfer, and maintaining a stable microhabitat of the biological community, promoting the biological community in the sewage treatment system to recover to the optimal state as soon as possible after being subjected to load shock, avoiding waste caused by excessive filler layout and system inefficiency and instability caused by insufficient layout, and significantly improving the pollutant removal efficiency, sludge reduction effect and operation stability of the biological predation sewage treatment system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a conceptual diagram of the optimization model of the microbial food web energy dissipation efficiency E, biological community diversity D and pollutant removal rate R in the biological predation sewage treatment system.

[0040] Figure 2 It is the energy transfer efficiency of the second trophic level food chain in the biological predation sewage treatment system with bacteria as prey. Figure 3 It is the energy transfer efficiency of the three-trophic-level food chain with rotifers as the intermediate trophic level in the biological predation sewage treatment system. DETAILED DESCRIPTION

[0041] The specific implementation of the present invention is described in detail below in conjunction with the technical scheme and the accompanying drawings.

[0042] The present invention is a method for optimizing the layout of fillers in a biological predator sewage treatment reactor, wherein the concept diagram of the optimization model of the microbial food web energy dissipation efficiency E, the biocommunity diversity D and the pollutant removal rate R is as shown in the figure. Figure 1 shown.

[0043] Taking a pilot plant for domestic sewage treatment as an example, the sewage treatment plant consists of 2 anaerobic tanks, 2 anoxic tanks, 10 aerobic tanks, 1 sedimentation tank and 1 clear water tank. Each anaerobic tank is 0.4m×0.5m×1.5m=0.3m 3 , the anoxic pool and the aerobic pool are each 0.5m×0.5m×1.5m=0.375m 3 The optimization method of the present invention is used to calculate the optimal filler dosage of the equipment, and the specific steps are as follows:

[0044] Step 1: Obtain basic data. First, select the filler to be laid for biofilm formation and preliminary experiments. Add suspended square polyurethane sponge fillers to the anaerobic and anoxic tanks. The size is 1.5cm×1.5cm×1.5cm, and the density is about 0.02g / cm 3 , the specific surface area is about 20000m 2 / m 3 (1000m 2 / kg); the modified nylon fiber filler is arranged in a curtain shape in the aerobic pool, with a specific surface area of ​​about 20000m 2 After biofilm formation, the water inflow, hydraulic retention time and water concentration (i.e. different loads) were adjusted to monitor TOC under different water inflow conditions; the fillers in different biochemical pools were sampled, and the biofilm weight per unit volume of filler was calculated by the difference in dry weight before and after biofilm formation; the proportion of live bacteria per unit volume of filler was determined by laser confocal microscopy, and the bacterial biomass B was obtained based on the biofilm weight and the proportion of live bacteria. 细菌 and density α, the bacterial species number S is obtained according to the ratio of bacterial biomass to the weight of a single bacterium 细菌 ; Sampling and microscopic examination of the protozoa on the filler to determine the species and number of protozoa per unit area of ​​filler S 原生动物 and S 后生动物 , using the volume method to calculate the biomass of protozoa B 原生动物 and B 后生动物 ; Through literature review, the carbon source utilization rates of major bacteria and protometazoans were obtained.

[0045] Step 2: Calculate R, D, and E. The carbon removal rate R is obtained by multiplying the product of the biomass B at each trophic level and the carbon source utilization rate r by TOC; 细菌 , S 原生动物 and S 后生动物 The Shannon diversity index H of the community was calculated and standardized as the diversity parameter D. A multi-level microbial food web was constructed based on the predation relationship between bacteria and protozoa, and different food chains with trophic levels of 2, 3, 4, and 5 were sorted out. The energy transfer efficiency e and dissipation efficiency E of food chains at different trophic levels were calculated. The energy transfer efficiency of some two-trophic level food chains with bacteria as prey (rotifers, nematodes, and copepods as predators) was shown in Figure 2 The energy transfer efficiency of the three-trophic-level food chain of bacteria → rotifer → nematode and bacteria → rotifer → copepod is shown in Figure 3 .

[0046] Step 3: Draw a three-dimensional graph of R, D, and E under different influent loads, calculate R×D×E and take the maximum value. The corresponding biomass B 细菌 , B 原生动物 and B 后生动物 is the optimal solution (range).

[0047] Step 4: According to the specific surface area and density of polyurethane sponge filler and modified nylon fiber filler, combined with biomass B, calculate the optimal layout of the two fillers. Among them, the optimized addition rate of polyurethane sponge filler in anaerobic tank is 2%, the optimized addition rate of polyurethane sponge filler in anoxic tank is 1.8%, and the optimized addition rate of modified nylon fiber filler in aerobic tank is 7.2%. If the volume ratio of anaerobic tank, anoxic tank and aerobic tank is changed, the filler layout needs to be recalculated and optimized.

[0048] The biological predation sewage treatment reactor with optimized filler arrangement according to the present invention can achieve continuous and stable operation for more than 80 days, with an influent TOC removal rate of 85-95%, an ammonia nitrogen removal rate of 97-100%, a total nitrogen removal rate of 81-84%, a suspended solids removal rate of 90-100%, and no residual sludge is generated.

[0049] Before optimizing the layout of the fillers, 0.3% square polyurethane sponge filler was added to the anaerobic tank, 0.24% square polyurethane sponge filler was added to the anoxic tank, and 6.7% modified nylon fiber filler was added to the aerobic tank. The TOC removal rate of the influent of the biological predation sewage treatment reactor was about 71-90%, the ammonia nitrogen removal rate reached 92-96%, the total nitrogen removal rate reached 40-71%, and the suspended solids removal rate reached 80-90%.

[0050] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, so that those skilled in the art can understand and apply the present invention, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, without having to go through creative work. Therefore, simple improvements made to the present invention by those skilled in the art based on the disclosure of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for optimizing the layout of fillers in a biological predator sewage treatment reactor, characterized in that: Here are the steps: Step 1: Establish a basic model for optimizing the layout of fillers in biological predation wastewater treatment reactors; f(R,E,D)=R×E×D (1) Among them, R is the removal rate of pollutants in the biological predator sewage treatment reactor, E is the energy dissipation efficiency of the microbial food web, and D is the diversity of the biological community in the system; the maximum value of each factor in the basic model of the optimization of the filler layout of the biological predator sewage treatment reactor is taken to obtain the optimization target; Step 2: Calculate the pollutant removal rate R; The pollutant removal rate R is completed by various organisms in the biological predation sewage treatment reactor and is characterized by the carbon removal rate. For a stable sewage treatment system, the pollutant removal rate of various organisms is closely related to their carbon source utilization rate r. The removal rate of carbon in the water body is estimated by the biomass B of each trophic level and the carbon source utilization rate r, that is: Among them, TOC is the total organic carbon content of the influent in the biological predation wastewater treatment reactor; Carbon source utilization by bacteria 18 O-H2O culture experiment was used to determine the carbon source utilization of protozoa and metazoa. 14 C isotope labeling method; Step 3: Calculate the energy dissipation efficiency E of the microbial food web; The energy dissipation efficiency E of the microbial food web is composed of the sum of the dissipation efficiencies of food chains of different lengths: E=E2+E3+E4+E5 (3) Among them, E2, E3, E4, and E5 represent the energy dissipation efficiency of the food chain composed of two, three, four, and five trophic levels respectively; the energy dissipation efficiency E of two adjacent trophic levels is calculated by the ratio of the biomass difference of the two trophic levels to the biomass of the lower trophic level. For a food chain containing n trophic levels, its energy dissipation efficiency is expressed as: Among them, B1 is the biomass of the first trophic level, that is, B 细菌 ; B n is the biomass of the nth trophic level, n = 2, 3, 4, 5; B n =B n-1 ×e, e is the energy transfer efficiency of the food chain, ranging from 5% to 63%; Step 4: Calculate the diversity D of the microbial food web community; The diversity of biological communities in biological predators in wastewater treatment reactors was calculated using the Shannon index H: Where S is the number of species in the community, P i is the proportion of the i-th species to all species; The Shannon index H of the biological community was standardized, and the calculated results were standardized within the range of (0,1], which was used as the biological community diversity D in the basic model for optimizing the layout of the filler in the biological predator sewage treatment reactor; Step 5: Perform multi-objective calculations on the basic model for optimizing the layout of the filler in the biological predator wastewater treatment reactor to obtain the optimized biomass of each trophic level; in the biological predator wastewater treatment reactor, as the pollutant concentration decreases, the pollutant removal rate increases, the microbial food web capacity dissipation efficiency increases, and the sludge reduction increases; within a certain range of pollutant concentrations, the diversity of the biological community is the highest, at this time the food chain is long, and the microbial food web energy dissipation efficiency is high; based on the above relationship, the above formulas are combined to calculate a set or a certain range of B 细菌,优化 , B 原生动物,优化 , B 后生动物,优化 Make R, E, and D in the biological predator sewage treatment reactor within the optimal range; Step 6: Biomass B obtained based on the optimization results 细菌,优化 Calculate the packing layout parameters; for a given packing, if its specific surface area M is known, the packing addition rate T can be calculated by the following formula: Bacteria, optimization = α × M × T (6) Where α is the density of bacteria in the biofilm on the filler, g / m 2 ; M is the specific surface area of ​​the filler, m 2 / m 3 ; T is the filler addition rate = filler volume / filler area volume; Based on the calculated specific surface area and addition rate of the filler, combined with the type and inherent properties of the filler, the weight or volume of the filler is inferred to obtain the filler layout amount.

2. The method for optimizing the layout of fillers in a biological predator sewage treatment reactor according to claim 1, characterized in that: Various types of organisms include bacteria, protozoa, and metazoa.

3. The method for optimizing the layout of fillers in a biological predator sewage treatment reactor according to claim 1, characterized in that: Bacterial biomass 细菌 The species number S is obtained by plate counting or DNA content determination, and then multiplied by the weight of a single bacterium.

4. The method for optimizing the layout of fillers in a biological predator wastewater treatment reactor according to claim 1, characterized in that: The biomass of protozoa and metazoa is obtained by multiplying the number of species S, the individual density ρ and the individual volume V, that is: B=S×ρ×V (7) Among them, the individual density is considered to be equal to the water body density, and the species number S and individual volume V are obtained by ultra-high power microscopy.

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