CN105868457B - The modeling method of nitrous oxide kinetic model during a kind of bio-denitrifying sewage - Google Patents

Abstract

The invention discloses N during a kind of bio-denitrifying sewage₂The modeling method of O kinetic model, comprising the following steps: (1) analyze N comprehensively₂O mechanism of production simultaneously accurately expresses N using half-reaction equation₂O mechanism of production；(2) comprehensive analyzing influence N₂The working condition that O is generated, determines key environmental factors；(3) based on No. 3 models (ASM3) of activated sludge and according to fixed half-reaction equation and key factor, the N based on ASM3 is constructed₂O kinetic model；(4) MATLAB optimization algorithm is utilized, parameter Estimation is carried out to the unknown parameter in modeling process and parameter identifies, and determines the confidence interval of unknown parameter；(5) using MATLAB mathematical software to N₂O kinetic model carries out dynamic analog, and carries out sensitivity analysis to all kinds of parameters, find out the key parameter being affected to model and modify；(6) N is established using MATLAB₂O kinetic model dynamic simulation software；The present invention has to N₂The advantages that expression of O mechanism of production is clearer, and predictive ability is more accurate.

Description

A Modeling Method for Nitrous Oxide Kinetic Model in the Process of Biological Denitrification of Sewage

technical field

The invention belongs to the technical field of sewage biological treatment and resource utilization, and particularly relates to a modeling method for a nitrous oxide kinetic model in the biological denitrification process of sewage.

Background technique

As a strong greenhouse gas, nitrous oxide (N ₂ O) can cause the destruction of the ozone layer and promote the formation of acid rain. It is also easily converted into secondary particulate pollutants under certain meteorological conditions, thereby aggravating haze. Therefore, N ₂ O has a compound pollution effect on the atmospheric environment. The biological treatment of sewage is considered to be one of the important anthropogenic sources of N ₂ O production. Therefore, the construction of the N ₂ O kinetic model based on the N ₂ O generation mechanism has important theoretical research significance and engineering application value.

At present, there is no research on the N ₂ O kinetic model in China. In contrast, foreign research on the N ₂ O kinetic model is relatively in-depth, but there are still many problems to be solved, such as insufficient description of the N ₂ O generation pathway and insufficient analysis of the key factors affecting N ₂ O production. In-depth and so on. At the same time, there are relatively few studies on computer simulation of N ₂ O production.

Since the ASM3 model is the latest version of the activated sludge model proposed by the International Water Association, it has a certain forward-looking and educational value, and is also a more reasonable basic structure of the activated sludge model. And the ASM3 model fully affirmed the metabolic pattern of "hydrolysis→storage→growth→endogenous respiration", which is in line with the current research on the metabolic process of heterotrophic and autotrophic bacteria in activated sludge. Therefore, the N ₂ O kinetic model established based on ASM3 will have the advantages of clearer mechanism expression, more detailed description of the half-reaction process, and more accurate model prediction ability. Based on the above analysis, the present invention proposes a modeling method for the N ₂ O kinetic model of the biological denitrification process of sewage to solve the above problems.

SUMMARY OF THE INVENTION

The present invention aims to solve the above-mentioned problems.

Therefore, the purpose of the present invention is to propose a modeling method for the kinetic model of nitrous oxide in the biological denitrification process of sewage, which is characterized by comprising the following steps: (1) comprehensively analyze the production mechanism and production path of N ₂ O, Use the half-reaction equation to accurately express the mechanism and way of N ₂ O production; (2) Comprehensively analyze various working conditions that affect the production of N ₂ O, and clarify the key factors affecting various biochemical reactions; (3) Based on activated sludge3 No. model (ASM3) and according to the determined half-reaction equations and key factors, using the relationship between stoichiometry and energy conversion, the matrix expression form of the model is established, and then the N ₂ O kinetic model based on ASM3 is established; (4) Using MATLAB to optimize The optimization algorithm is used to estimate and identify the unknown parameters in the modeling process, and determine the confidence interval of the unknown parameters; (5) After the parameters are determined, use MATLAB mathematical software to write a program to dynamically simulate the N ₂ O kinetic model , and conduct sensitivity analysis on kinetic and chemometric parameters to find out the key parameters that have the greatest impact on the model simulation effect and modify them; (6) Based on the MATLAB graphical user interface design, the dynamic simulation software of N ₂ O kinetic model is established;

According to the model establishment method proposed in the present invention, a more comprehensive and accurate N ₂ O kinetic model can be established. In addition, the modeling method proposed by the present invention may also have the following additional technical features:

Further, the N ₂ O production pathways described in step (1) include AOB denitrification, heterotrophic denitrification, NOH chemical analysis, and microbial decay processes.

Further, the working conditions and key factors described in step (2) include dissolved oxygen, pH value, temperature, COD/N ratio, and NO ₂ ^{-concentration} .

Further, the MATLAB optimization algorithm described in step (4) is a nonlinear least squares method, and a 95% confidence interval can be obtained.

Further, the dynamic simulation program algorithm described in step (5) is the fourth and fifth order Runge-Kutta algorithm and the variable order algorithm (BDFs, Gear) based on numerical difference; the sensitivity analysis is the most commonly used relative sensitivity function. S _j ⁱ .

The invention is a modeling method of N ₂ O dynamic model based on ASM No. 3 model and using MATLAB software. The present invention not only comprehensively considers the N ₂ O production pathway, but also pays attention to the influence of microorganism growth attenuation and main environmental factors on the N ₂ O production; not only uses MATLAB software to fit and correct the parameters of the model, but also develops N ₂ O dynamic simulation software. In addition, the technical solution of the present invention has a clear and simple idea, and the modeling time and cost can be greatly saved by rationally using the MATLAB software.

Description of drawings

FIG. 1 is a schematic flowchart of a modeling method for a nitrous oxide kinetic model in a biological denitrification process of sewage proposed by the present invention.

Detailed ways

Fig. 1 is the schematic flow chart of the modeling method of the nitrous oxide kinetic model of a kind of sewage biological denitrification process proposed by the present invention, and each step in the modeling method of the N ₂ O kinetic model is described in detail below with reference to the accompanying drawings:

Step (1): Comprehensively analyze the production mechanism and production pathway of N ₂ O, and use the half-reaction equation to accurately express the production mechanism and pathway of N ₂ O.

Specifically, by analyzing and summarizing experimental and literature data, it can be seen that when environmental conditions affect the activity of NOR biological enzymes, N ₂ O will be produced, and the main pathways of N ₂ O production are AOB denitrification, heterotrophic denitrification, NOH Chemical analysis and microbial decay processes. After the production mechanism and production route of N ₂ O are clarified, the half reaction equation can be used to accurately express the production mechanism and production route of N ₂ O.

Step (2): Comprehensively analyze various working conditions that affect the production of N ₂ O, and clarify the key environmental factors affecting various biochemical reactions.

Specifically, by analyzing and summarizing experimental and literature data, it can be known that the most essential reason for the production of N ₂ O is the inactivation or activity reduction of NOR biological enzymes. The main working conditions and key factors that lead to the inactivation or activity reduction of NOR biological enzymes are dissolved oxygen, pH value, temperature, COD/N ratio, and NO ₂ ^{-concentration} .

Step (3): Based on the activated sludge model No. 3 (ASM3) and according to the determined half-reaction equations and key factors, using the relationship between stoichiometry and energy conversion between components, the matrix expression form of the model is established, and then the ASM3-based model is established. _N2O kinetic model.

Specifically, after completing steps (1) and (2), using the relationship between stoichiometry and energy conversion between components, the material components and reaction rate equations related to the production of N ₂ O are added to the framework of the ASM3 model. . The N ₂ O kinetic model was then expressed, and the ASM3 model was extended accordingly.

Step (4): Use the MATLAB optimization algorithm to estimate and identify the unknown parameters in the modeling process, and determine the confidence interval of the unknown parameters.

Specifically, after building the N ₂ O kinetic model based on the ASM3 model, the MATLAB optimization algorithm was used to fit and solve the unknown parameters in the new model, and the 95% confidence interval of the unknown parameters was obtained. The main algorithm of its application is the nonlinear least squares method.

Step (5): After the parameters are determined, use MATLAB mathematical software to write a program to dynamically simulate the N ₂ O kinetic model, and perform sensitivity analysis on the kinetic and chemometric parameters to find out the key that has the greatest impact on the model simulation effect. parameters and modify them.

Specifically, when using MATLAB for dynamic simulation of the N ₂ O dynamic model, the main programs invoked are the fourth- and fifth-order Runge-Kutta algorithm and the variable-order algorithm based on numerical difference (BDFs, Gear). When performing sensitivity analysis on parameters, the relative sensitivity function S _ji is mainly used ^.

Step (6): Based on the MATLAB graphical user interface design, the dynamic simulation software of the N ₂ O kinetic model is established.

Specifically, after completing the basic work of establishing the N ₂ O dynamic model, the various programs written before were integrated, and then MATLAB was used to design the graphical user interface, which made the interaction between the model and the user more simple and convenient.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims (1)

1. a kind of modeling method of bio-denitrifying sewage process nitrous oxide kinetic model, which is characterized in that including following step It is rapid:

Step (1): N is analyzed comprehensively₂The mechanism of production and the way of production of O, accurately expresses N using half-reaction equation₂The generation of O Mechanism and approach；

Specifically, will lead to N when the activity of environmental influence NOR biological enzyme₂The generation of O, and N₂The way of production master of O There are AOB denitrification, heterotroph denitrification, NOH chemical analysis and microorganism attenuation process；Specifying N₂The mechanism of production of O After the way of production, i.e., N is accurately given expression to using half-reaction equation₂The mechanism of production and the way of production of O；

Step (2): comprehensive analyzing influence N₂All kinds of working conditions that O is generated, clearly influence the critical environments of all kinds of biochemical reactions because Son；

Specifically, leading to N₂O generates most essential reason, that is, NOR biological enzyme inactivation or activity and reduces, and NOR biological enzyme is caused to lose The working condition and key factor that living or activity reduces mainly have dissolved oxygen, pH value, temperature, COD/N ratio, NO₂ ^-Concentration；

Step (3): based on No. 3 models (ASM3) of activated sludge and according to fixed half-reaction equation and key factor, benefit With energy transforming relationship between Chemical Measurement and component, establishes the expression matrix form of model and then establish the N based on ASM3₂O Kinetic model；

Specifically, after completing step (1) and step (2), using energy conversion relation between Chemical Measurement and component, Increase and N in the framework of ASM3 model₂O generates related material composition and reaction rate equation, and then expresses N₂O dynamics Model, while ASM3 model is extended accordingly；

Step (4): utilizing MATLAB optimization algorithm, carries out parameter Estimation to the unknown parameter in modeling process and parameter is known Not, and determine unknown parameter confidence interval；

Specifically, having constructed the N based on ASM3 model₂After O kinetic model, using MATLAB optimization algorithm, to new modeling Unknown parameter in type is fitted solution, and obtains the confidence interval of unknown parameter 95%；The MATLAB optimization algorithm is Nonlinear least square method；

Step (5): after parameter determines, program is write to N using MATLAB mathematical software₂O kinetic model carries out dynamic analog It is quasi-, and sensitivity analysis is carried out to dynamics and Chemical Measurement parameter, it finds out to the maximum key of modeling influential effect Parameter is simultaneously modified；

Specifically, using MATLAB to N₂When O kinetic model carries out dynamic analog, the program mainly called is four or five ranks Runge-Kutta algorithm and variable order algorithm (BDFs, Gear) based on diff；When to parameter progress sensitivity analysis When, that mainly use is relative sensitivity function S_j ⁱ；

Step (6): it is based on MATLAB GUI Design, establishes N₂O kinetic model dynamic simulation software.