An Optimization Method for Packing Layout of a Biological Predation Sewage Treatment Reaction Device

Abstract

The present invention discloses an optimized method for arranging fillers in a biological predation sewage treatment reaction device. By establishing an optimization model of the energy dissipation efficiency E of the microbial food web, the biodiversity 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 arrangement amount of fillers in the sewage biological treatment reactor is calculated. The filler dosage arranged according to the calculation results can improve the pollutant removal efficiency and sludge reduction effect, enhance the shock load resistance ability of the multi-level microbial food web, restore the shocked microbial food web to the optimized stable state, and ultimately improve the stability and efficiency of the entire biological predation sewage treatment system. The method of the present invention avoids the waste caused by excessive arrangement of fillers and the problems such as low efficiency and instability of the system caused by insufficient arrangement, and significantly improves the pollutant removal efficiency, sludge reduction effect and operation stability of the biological predation sewage treatment system.

Description

Technical Field

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

[0002] The biological method is the most commonly used technical method in sewage treatment plants worldwide at present. However, traditional sewage biological treatment often produces a large amount of excess sludge. Therefore, it is extremely urgent to develop a green and low-carbon in-situ sludge reduction technology.

[0003] Among various technologies for improving sludge reduction efficiency based on enhancing microbial metabolism, the biological predation sludge reduction technology has received 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 such as worm reactors, food chain reactors, integrated fixed biofilms, and biological contact oxidation processes. The main purpose is to construct a microbial food chain (network) in the sewage biological treatment system, and by regulating process parameters such as hydraulic retention time and aeration volume, extend the food chain in the sewage treatment system, thereby improving the biological predation effect and energy dissipation efficiency, and strengthening the sludge reduction effect.

[0004] However, up to now, the microbial food web structure and function in the sewage treatment system have not been fully described in the existing literature reports. The research on the energy transfer efficiency of the microbial food web in sewage is still blank. It is not possible to quantify the transfer efficiency of different microbial food chains in the sewage treatment system, and there is a lack of technical methods for regulating the microbial food chain (network) in the sewage system and improving the energy transfer efficiency of the microbial food web in sewage.

[0005] As a carrier for the attachment of biological communities and biofilms in sewage treatment reactors, packing plays an important role in improving the metabolic efficiency of microorganisms and adjusting the structure and function of microbial communities. By modifying the packing, the specific surface area of the packing can be increased, and the microbial load can be improved; increasing the amount of packing, the number of reactor stages, or prolonging the hydraulic retention time can extend the food chain, thereby improving the sludge reduction effect. Existing literature has reported on the effects of the layout form (curtain-like, vortex-like, suspended, etc.), type (nylon fiber, graphene fiber, activated carbon, polyurethane sponge, etc.) of the packing on sewage treatment, sludge reduction effect, and microbial activity. The literature "Study on the Pollutant Removal Efficiency and Microbial Characteristics of MPR Composite with Different Packings" reported the pollutant removal effect and sludge reduction performance of a micro-pressure internal circulation multi-biological phase reactor (MPR) with the same proportion (10%) of different packing carriers (spherical polypropylene hollow balls, cylindrical high-density polyethylene K-type, square polyurethane porous foam packing carriers). By detecting the characteristics of activated sludge and biofilms and the structure of microbial flora, the pollutant removal and sludge reduction effects were verified, and the most suitable packing type for the MPR composite packing system was obtained, but the impact of the packing on protozoa and metazoa and sludge reduction was not considered. The literature "Study on the Strengthening Effect of Packing on the In-situ Side-Flow Sludge Reduction Process" analyzed the effects of ultrasonic coupling with cylindrical polyethylene carrier element packing and packing filling rate on pollutant removal, sludge reduction effect, and membrane fouling, and explored its microbial population structure and sludge reduction functional flora, but did not consider the impact of the packing on protozoa and metazoa and their stability. The literature "Study on the Sludge Reduction Method Based on the Biological Predation of Tubifex in the A / O Process" reported the effects of combined packing and three-dimensional fiber packing on the attachment growth of Tubifex and its sludge reduction effect, but did not consider the stability of the Tubifex population. The literature "Pilot Study on the Packing Filling Rate of the 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 obtained that 35% of the suspended packing was the optimal dosage. To sum up, existing reports mostly judge the amount of packing based on experience or only conduct a small number of experimental comparative studies, which is likely to cause problems such as overfilling or insufficient filling rate, and mainly consider the role of microbial attachment amount in pollutant purification and sludge reduction, without providing a scientific calculation method for optimizing packing layout, not being applicable to biological predation sewage treatment systems, and being difficult to truly achieve the efficient performance of packing, the stability of sewage treatment systems, and the improvement of sludge reduction effect.

[0006] To achieve the optimal configuration of the packing in a biological predation sewage treatment reactor, there is an urgent need to develop a calculation method for packing layout that comprehensively considers the pollutant degradation efficiency, sludge reduction mechanism, biological community stability, energy dissipation and transfer efficiency of the microbial food web (chain). Summary of the Invention

[0007] The present invention provides an optimization method for the packing layout of a biological predation sewage treatment reaction device. By establishing an optimization model of the energy dissipation efficiency E, biological community diversity D, and pollutant removal rate R of the microbial food web in a 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 the packing in the sewage biological treatment reactor is calculated. The packing dosage arranged according to the calculation results can improve the pollutant removal efficiency and sludge reduction effect, while enhancing the shock load resistance ability of the multi-level microbial food web, enabling the impacted microbial food web to recover to the optimized stable state, and ultimately improving the stability and efficiency of the entire biological predation sewage treatment system.

[0008] The technical solution of the present invention:

[0009] An optimization method for the packing layout of a biological predation sewage treatment reaction device is as follows:

[0010] Step 1: Establish an optimization basic model for the packing layout of a biological predation sewage treatment reactor;

[0011] f(R,E,D)=R×E×D (1)

[0012] Wherein, R is the pollutant removal rate in the biological predation 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 values are taken for each factor in the optimization basic model of the packing layout of the biological predation sewage treatment reactor to obtain the optimization objective;

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

[0014] The pollutant removal rate R is jointly completed by various organisms (including main groups such as bacteria, protozoa, and metazoans) 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, and the carbon removal rate of the water body can be estimated through 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 sewage treatment reactor. The carbon source utilization rate of bacteria is related to the type of packing, and the packing with conductivity and enhanced electron transfer ability can improve the carbon source utilization rate r of bacteria 细菌 , through 18 the O-H2O culture experiment determination, and the carbon source utilization rates of protozoa and metazoans are determined by 14 the 14C isotope labeling method;

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

[0018] The biomass of protozoa and metazoan 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 metazoan, due to their high water content, the individual density of organisms can be approximately considered equal to the density of water body (that is, assume the density is ρ = 1 g / mL), and the number of species S and the individual volume V are obtained by ultra-high magnification microscopy inspection 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 energy dissipation efficiencies of food chains of different lengths:

[0023] E = E2 + E3 + E4 + E5 (4)

[0024] Among them, E2, E3, E4, and E5 respectively represent the energy dissipation efficiencies of food chains composed of the second, third, fourth, and fifth trophic levels; limited by the nutrients and environmental conditions of the sewage treatment system, the trophic levels of the microbial food web in the sewage treatment system generally do not exceed 5 levels, such as bacteria → rotifers → cladocerans → copepods → insecta. For the energy dissipation efficiency E of two adjacent trophic levels, it can be calculated by the ratio of the biomass difference between 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, B1 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, the lower the energy transfer efficiency, and the higher the dissipation efficiency E. Therefore, extending the food chain can increase energy dissipation and improve the effect of biological predation sludge reduction.

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

[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] B 细菌,优化 =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] Advantages of the present invention: According to the characteristics of the biological predation sewage treatment system, the present invention establishes an optimization model for the energy dissipation efficiency E of the microbial food web, the biodiversity D of the biological community, and the pollutant removal rate R. Taking the biomass B as a medium, the relationships between the specific surface area and dosing rate of the packing and E, H, and R are established. Through precise calculation, the optimal packing layout conditions are obtained, improving the utilization rate of the packing and giving full play to the functions of the packing in attaching biofilms, enhancing microbial electron transfer, and maintaining a stable microhabitat for the biological community. This promotes the biological community in the sewage treatment system to quickly recover to the optimal state after being impacted by the load, avoiding problems such as waste caused by excessive packing layout and inefficiency and instability of the system caused by insufficient layout, and significantly improving the pollutant removal efficiency, sludge reduction effect, and operation stability of the biological predation sewage treatment system. Description of the Drawings

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

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

[0041] The following describes in detail the specific embodiments of the present invention in combination with the technical solutions and the drawings.

[0042] The present invention is an optimization method for the packing layout of a biological predation sewage treatment reaction device, and the conceptual diagram of the optimization model for the energy dissipation efficiency E of the microbial food web, the biodiversity D of the biological community, and the pollutant removal rate R is as Figure 1 shown.

[0043] Taking a certain actual domestic sewage treatment pilot equipment as an example, the sewage treatment equipment 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 , and each anoxic tank and aerobic tank is 0.5m×0.5m×1.5m = 0.375m 3 . Using the optimization method in the present invention to calculate the optimal packing dosage of the equipment, the specific steps are as follows:

[0044] Step 1: Obtain basic data. First, select the packing to be laid out for film hanging and pre-experiments. Suspended square polyurethane sponge packing is added to the anaerobic tank and the anoxic tank, with a size of 1.5cm×1.5cm×1.5cm and a density of about 0.02g / cm 3, with a specific surface area of approximately 20000 m 2 / m 3 (1000 m 2 / kg); Modified nylon fiber fillers are arranged in a curtain shape in the aerobic tank, with a specific surface area of approximately 20000 m 2 / kg. After the biofilm is formed, adjust the influent flow rate, hydraulic retention time, and influent concentration (i.e., different loads), and monitor the TOC under different influent conditions; sample the fillers in different biochemical tanks, and calculate the biofilm weight per unit volume of the filler through the dry weight difference before and after the biofilm formation on the filler; use laser confocal microscopy to measure the proportion of live bacteria per unit volume of the filler, and obtain the bacterial biomass B 细菌 and density α, and obtain the number of bacterial species S according to the weight ratio of the bacterial biomass to that of a single bacterium 细菌 ; Sample and microscopically examine the protozoa and metazoa on the filler to determine the types and numbers S 原生动物 and S 后生动物 of the protozoa and metazoa per unit area of the filler, and use the volume method to calculate the biomass B 原生动物 and B 后生动物 of the protozoa and metazoa; Through literature review, obtain the carbon source utilization rates of the main bacteria, protozoa, and metazoa

[0045] Step 2: Calculate R, D, and E. Obtain the carbon removal rate R by dividing the product of the biomass B of each trophic level and the carbon source utilization rate r by the TOC; Calculate the Shannon diversity index H of the community according to S 细菌 、S 原生动物 and S 后生动物 , and standardize it to the diversity parameter D; Construct a multi-level microbial food web based on the predation relationships between bacteria, protozoa, and metazoa, sort out different food chains with trophic levels of 2, 3, 4, and 5, and calculate the energy transfer efficiency e and dissipation efficiency E of different trophic level food chains. Among them, the energy transfer efficiency of the partial second trophic level food chain with bacteria as prey (rotifers, nematodes, and copepods as predators) is shown in Figure 2 , and the energy transfer efficiency of the three trophic level food chains of bacteria → rotifers → nematodes and bacteria → rotifers → copepods is shown in Figure 3 .

[0046] Step 3: Draw a three-dimensional diagram of R, D, and E under different influent loads, calculate R×D×E and take the maximum value. At this time, the corresponding biomass B 细菌 、B 原生动物 and B 后生动物 are the optimal solutions (range).

[0047] Step 4: Calculate the optimized deployment amounts of the two types of fillers based on the specific surface areas and densities of the polyurethane sponge filler and the modified nylon fiber filler, in combination with the biomass B. Among them, the optimized dosing rate of the polyurethane sponge filler in the anaerobic tank is 2%, the optimized dosing rate of the polyurethane sponge filler in the anoxic tank is 1.8%, and the optimized dosing rate of the modified nylon fiber filler in the aerobic tank is 7.2%. If the volume ratios of the anaerobic tank, anoxic tank, and aerobic tank are changed, it is necessary to recalculate and optimize the filler deployment.

[0048] The biological predation sewage treatment reactor with optimized filler deployment according to the present invention achieves continuous and stable operation for more than 80 days, with the influent TOC removal rate reaching 85 - 95%, the ammonia nitrogen removal rate reaching 97 - 100%, the total nitrogen removal rate reaching 81 - 84%, the suspended solid removal rate reaching 90 - 100%, and no excess sludge is generated.

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

[0050] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, facilitating those skilled in the art of this technology to understand and apply the present invention. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, several simple deductions or substitutions can be made without departing from the inventive concept of the present invention, without the need for creative labor. Therefore, simple improvements made by those skilled in the art based on the disclosure of the present invention should fall within the protection scope 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: B 细菌,优化 =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.

Images