CN104238586A - Method and system for ammonia nitrogen control in biological sewage treatment process - Google Patents

Abstract

The invention discloses a method and a system for ammonia nitrogen control in a biological sewage treatment process. The method and the system are used for precisely controlling effluent ammonia nitrogen in the biological sewage treatment process. Two control loops including an outer loop and an inner loop are cascaded in the system for ammonia nitrogen control, the outer loop is an ammonia nitrogen-dissolved oxygen set value control loop, and the inner loop is a dissolved oxygen set value-aeration quantity control loop. The method includes: using a mathematical model for solution so as to stabilize an actual ammonia nitrogen value of a reaction tank to a dissolved oxygen value required by a target value, and setting the dissolved oxygen value as a dissolved oxygen set value; adjusting aeration quantity by a dissolved oxygen controller to enable dissolved oxygen in the reaction tank to be stabilized around the set value. The method and the system for ammonia nitrogen control in the biological sewage treatment process has the advantages that directly influencing or controlling effluent ammonia nitrogen of a biochemical pool is realized; optimization of a denitrification process is facilitated, the defect of excessiveness or deficiency in aeration in current denitrification processes can be overcome, and effluent ammonia nitrogen removal effects and energy saving and consumption reduction capabilities of sewage plants are improved.

Description

Ammonia control system and method in a kind of sewage biological treatment technique

Technical field

The present invention relates to ammonia nitrogen amount technical field of automatic control in wastewater treatment, especially relate to the ammonia control system and method based on accurate aeration system in a kind of sewage biological treatment technique.

Background technology

Along with social development, urbanization and industrialized process, be discharged into natural water without the life fully processed, industrial waste water in a large number, make water pollutions phenomenon become the serious problems jeopardizing water environment and water safety.In water pollution problems, the eutrophication of water body is particularly outstanding, and these two kinds of nutrients of nitrogen, phosphorus serve main effect wherein.Therefore, to the removal of nitrogen, P elements in sewage, become the basic function of municipal sewage plant's indispensability, the standard of the control polluted articles discharge that country puts into effect also proposes strict requirement to the reduction of discharging of nitrogen, phosphorus.

Current, the main way of sewage treatment plant's denitrogenation, still depends on nitrification and denitrification process, namely based on the activated sludge process of A2O and modification thereof.Conventional nitrification-denitrification denitrification process, often also exists the defects such as efficiency is not high, energy consumption is larger.Because nitrifying process is an aerobic process, certain aeration rate is therefore needed to carry out to facilitate nitration reaction, to impel water outlet ammonia nitrogen up to standard.But too much aeration rate can bring the waste in energy consumption, although be conducive to the removal of ammonia nitrogen, but due to the effect of interior backflow, bring impact may to the denitrification process of oxygen-starved area, suppress the carrying out of denitrification process, cause the removal effect of total nitrogen not ideal enough.Therefore in denitrification process, aeration rate is not the bigger the better, but needs just right, can meet nitrated demand, not need again too high in order to avoid cause the waste of energy consumption and affect denitrification.This just proposes the control overflow of accurate aeration to denitrification process, to realize " energy control for need ".

Accurate aeration system (being called for short AVS) is a kind of technological means jointly controlled based on activated sludge model and fan blower-valve, for the Precise control of Sewage Plant, by arranging the dissolved oxygen DO desired value that can make water outlet water quality reaching standard, impel fan blower to export and distributed by valve to make the dissolved oxygen DO of aerobic zone reach the tolerance of desired value.This technological means, under the prerequisite of basic guarantee standard water discharge, saves aeration rate, namely energy consumption, namely realizes expection standard water discharge with less cost or energy consumption.

As shown in Figure 1, the control principle schematic diagram of accurate aeration system, accurate aeration system can automatically adjust to the tolerance distribution of fan blower and controlled aeration unit, the air demand of each dissolved oxygen DO control zone is distributed according to actual water quality and quantity data intelligence, automatic adjustment gas flow setting value, aeration as required.Total air demand is calculated by model according to the signal such as the water yield, water quality by on-the-spot each controlled aeration unit, and sends instruction by system control cabinet to fan blower master control cabinet MCP, carries out tolerance adjustment by fan blower stator or frequency converter; Regulate the aperture of multiple electric air flow control valve simultaneously, make the actual tolerance in controlled aeration unit arm reach institute's air demand, serve the effect that tolerance is distributed.

Arbitrary setting value that accurate aeration system can control between 0.5 ~ 5.0mg/L dissolved oxygen DO in aeration tank, control accuracy setting value ± 0.5mg/L within the scope of, to meet in aerobic section to the different requirements of dissolved oxygen concentration in zones of different, as shown in Figure 2.

But the control mode of existing accurate aeration system and control objectives are remote effect or the means controlling this effluent quality of dissolved oxygen DO.And effluent quality standard does not relate to dissolved oxygen DO, and for be chemical oxygen demand (COD) (COD), ammonia nitrogen etc., therefore existing accurate aeration system still can not reach the object directly controlling biochemistry pool water outlet ammonia nitrogen.

Summary of the invention

The object of the present invention is to provide the ammonia control system and method in a kind of sewage biological treatment technique, overcome the defect of prior art, the basis of existing accurate aeration system makes improvements, adopt the control mode of cascade between ammonia nitrogen-dissolved oxygen DO-tolerance three, by the ammonia nitrogen desired value arranged, accurate control makes the ammonia nitrogen value in sewage reach aeration rate needed for desired value, ensureing on the basis that effluent quality is up to standard, save aeration rate, namely realize the standard water discharge of expection with minimum cost or energy consumption.

For achieving the above object, technical scheme of the present invention is:

Ammonia control system in a kind of sewage biological treatment technique, described ammonia control system comprises mathematical model, dissolved oxygen controller, controlled aerator and sewage reaction tank, dissolved oxygen sensing instrument and ammonia nitrogen measuring instrument is provided with in described sewage reaction tank, the ammonia nitrogen actual value in reaction tank measured by described ammonia nitrogen tester, and described mathematical model is according to the ammonia nitrogen desired value of described ammonia nitrogen actual value and setting, and the ammonia nitrogen in setting reaction tank reaches the dissolved oxygen DO setting value of desired value; Described dissolved oxygen sensing instrument records the dissolved oxygen DO actual value in reaction tank, and described dissolved oxygen controller exports according to described dissolved oxygen DO setting value and the described controlled aerator of dissolved oxygen DO actual value control and ammonia nitrogen can be made to reach the tolerance of desired value in reaction tank.

Preferably, described ammonia nitrogen measuring instrument comprises the first online ammonia nitrogen instrument described in the first online ammonia nitrogen instrument and the second online ammonia nitrogen instrument and is arranged on the front end of sewage reaction tank aerobic section, for measuring the ammonia nitrogen actual value of aerobic section front end; Described second online ammonia nitrogen instrument is arranged on sewage reaction tank aerobic section 1/2 ~ 3/4 place from front to back, for measuring the ammonia nitrogen actual value at aerobic section 1/2 ~ 3/4 place.

Preferably, described ammonia control system dynamically sets described dissolved oxygen DO setting value.

Preferably, described ammonia control system dynamically sets described dissolved oxygen DO setting value by artificial dynamic time sequence or full-automatic mode.

Preferably, described artificial dynamic time sequence mode is by manually providing the dissolved oxygen DO setting sequence in the water inlet cycle, and described ammonia control system, according to described dissolved oxygen DO setting sequence, realizes the dynamic setting of dissolved oxygen DO setting value.

Preferably, described full-automatic mode be described ammonia control system according to the water inlet in reaction tank, go out water condition, set out dissolved oxygen DO setting value in real time.

Preferably, the aeration rate needed for desired value is reached according to described dissolved oxygen DO setting value and the dissolved oxygen DO actual value ammonia nitrogen controlled in sewage reaction tank.

Present invention also offers another one technical scheme: a kind of ammonia control method in sewage biological treatment technique, reaches the aeration rate needed for desired value for the ammonia nitrogen accurately controlled in sewage reaction tank, comprising:

Measure the ammonia nitrogen actual value in sewage reaction tank;

Dissolved oxygen DO setting value is dynamically set according to described ammonia nitrogen actual value and the ammonia nitrogen desired value that arranged;

Measure the dissolved oxygen DO actual value in sewage reaction tank;

The aeration rate needed for desired value is reached according to described dissolved oxygen DO setting value and the dissolved oxygen DO actual value ammonia nitrogen controlled in sewage reaction tank.

Further, the mode of described dynamic setting dissolved oxygen DO setting value is artificial dynamic time sequence mode or full-automatic mode.

Again, described artificial dynamic time sequence mode is the dissolved oxygen DO setting sequence by manually providing in the water inlet cycle, according to described dissolved oxygen DO setting sequence, realizes the dynamic setting of dissolved oxygen DO setting value.

Further, described full-automatic mode is according to the water inlet in reaction tank, goes out water condition, set out dissolved oxygen DO setting value in real time.

The present invention is the expansion of existing accurate aeration system, takes cascade Mach-Zehnder interferometer mode, first solves the dissolved oxygen DO of actual ammonia nitrogen value stabilization required for its desired value of reaction tank by means of mathematical model, this dissolved oxygen value is set as the dissolved oxygen DO setting value of reaction tank; Then, regulate aeration rate by dissolved oxygen controller, make the dissolved oxygen stable of reaction tank near setting value.The present invention can automatically carry out the setting of resolving in dynamic state oxygen according to the change of water inlet factor, environmental factor and technology controlling and process target, also manually can set sequence chronologically and dynamically set dissolved oxygen DO, and calculate air demand on this basis, then reach the target of energy control for need, distribution by accurate aeration system, realize effluent quality optimization and save energy and reduce the cost.

Compared with prior art, the invention has the beneficial effects as follows:

1, flow of inlet water, influent COD and the influent ammonia nitrogens etc. that change according to the moment of the present invention, calculate the aeration rate of degraded needed for these ammonia nitrogens in real time, reach directly impact or control the object of biochemistry pool water outlet ammonia nitrogen.

2, the present invention contributes to the optimization of denitrification process, alleviates the drawback of ubiquitous excess aeration or deficiency in current denitrification process, the removal effect of lifting sewage plant effluent ammonia nitrogen and energy-saving and cost-reducing level.

3, the present invention carries out the setting of resolving in dynamic state oxygen, provide the dissolved oxygen DO setting value of each dissolved oxygen DO control zone in real time, and according to the dynamic auto adjustment dissolved oxygen DO of dissolved oxygen DO actual value near its setting value, avoid dissolved oxygen DO to set response and bring impact to sewage treatment process and water outlet not in time.

4, ammonia control system of the present invention can the arbitrary setting value of ammonia control in aeration tank between 0.5 ~ 20.0mg/L, control accuracy setting value ± 0.5mg/L within the scope of, to meet in aerobic section in zones of different the different requirements of ammonia nitrogen concentration.

Accompanying drawing explanation

Fig. 1 is the control principle schematic diagram of the existing accurate aeration system of the present invention;

Fig. 2 is the scope schematic diagram of the present invention's existing accurate aeration Systematical control dissolved oxygen DO setting value;

Fig. 3 is the control principle schematic diagram of ammonia control system of the present invention;

Fig. 4 is the schematic diagram that ammonia control system of the present invention installs online ammonia nitrogen instrument;

Fig. 5 is the form schematic diagram of the dissolved oxygen value that the artificial dynamic time sequence mode of the present invention sets;

Fig. 6 is the principle schematic of the full automatic dissolved oxygen DO setup control of the present invention;

The schematic flow sheet of Tu7Shi embodiment of the present invention sewage treatment plant technique;

Fig. 8 is that in embodiment of the present invention reaction tank, ammonia nitrogen instrument specifically arranges schematic diagram;

Fig. 9 is the Control platform schematic diagram under the artificial resolving in dynamic state oxygen setting of the embodiment of the present invention;

Figure 10 is the water outlet ammonia nitrogen curve synoptic diagram that in the embodiment of the present invention, each ammonia nitrogen instrument records;

Figure 11 is the schematic flow sheet of ammonia control method of the present invention.

Embodiment

Below in conjunction with embodiment and accompanying drawing, technical scheme of the present invention is described further.

Ammonia control system in disclosed a kind of sewage biological treatment technique, for the direct ammonia nitrogen desired value according to effluent quality, accurate control makes the aeration rate reached in reaction tank needed for the desired value of ammonia nitrogen, is applicable to the active sludge treatment process of various main flow.

The factor affecting ammonia nitrogen degradation in biochemical wastewater treatment system mainly contains temperature, dissolved oxygen DO, the residence time, sludge age or sludge concentration etc., in these factors, for the system of opening, only has dissolved oxygen DO to be controlled.Therefore, the principle of ammonia control system of the present invention is flow of inlet water, influent COD and influent ammonia nitrogen etc. according to moment change, and the moment calculates the aeration rate of degraded needed for these ammonia nitrogens, to enable water outlet COD and ammonia nitrogen stably reaching standard.

As shown in Figure 3, ammonia control system of the present invention comprises sewage reaction tank 1, mathematical model 2, dissolved oxygen controller 3 and controlled aerator 4; Comprise the anaerobism section, anoxic section and the aerobic section that are connected successively in sewage reaction tank, dissolved oxygen sensing instrument 5 and ammonia nitrogen measuring instrument 6 are set at the aerobic section of reaction tank, be respectively used to dissolved oxygen DO actual value and the ammonia nitrogen actual value of measuring aerobic section.

The present invention solves dissolved oxygen DO ammonia nitrogen actual value be stabilized in required for its desired value by means of mathematical model, this dissolved oxygen value is set as the dissolved oxygen DO setting value of dissolved oxygen controller; Dissolved oxygen controller regulates the aeration rate of controlled aerator according to dissolved oxygen DO setting value and dissolved oxygen DO actual value, makes the dissolved oxygen stable of the control zone in reaction tank near setting value.

Export by controlling fan blower-valve system the tolerance making the dissolved oxygen DO in sewage reaction tank reach desired value with existing accurate aeration system, thus the technology of remote effect or control reaction tank effluent quality is different, the present invention is on the basis of existing accurate aeration system, adopt cascade Mach-Zehnder interferometer mode, making the ammonia nitrogen in sewage reaction tank reach the tolerance of desired value by controlling fan blower-valve system output, realizing the object of water outlet ammonia nitrogen in directly impact or control reaction tank.

Particularly, control system middle rank of the present invention is associated with two control loops, is respectively external loop and inner looping, wherein, external loop is ammonia nitrogen-dissolved oxygen DO set value calculation loop, is a control loop of the present invention's cascade on the control loop of existing accurate aeration system; Inner looping is dissolved oxygen DO setting value-aeration control loop, is the control loop of existing accurate aeration system, and two loops are associated together by dissolved oxygen DO setting value.

According to the control principle of ammonia control system of the present invention, at the diverse location of reaction tank aerobic section, the online ammonia nitrogen instrument of multiple stage is set, to arrange two online ammonia nitrogen instrument, as shown in Figure 4, an online ammonia nitrogen instrument 7 is installed in the front end of aerobic section, as measuring instrument, for detecting the initial ammonia nitrogen actual value of aerobic section; Another online ammonia nitrogen instrument 8 is installed as prosecution instrument at 1/2 ~ 3/4 place (preferably 2/3 place) of aerobic section, for measuring the ammonia nitrogen actual value at aerobic section 1/2 ~ 3/4 place, thus arranges and control ammonia nitrogen desired value.

Easy in order to describe below, the front end of aerobic section is defined as aerobic section 1 to the region at its 2/3 place, and 2/3 place of aerobic section is defined as aerobic section 2 to the region of its end.

The corresponding online ammonia nitrogen instrument of dissolved oxygen sensing instrument also arranges two, is respectively used to the dissolved oxygen DO actual value measuring aerobic section 1 and aerobic section 2.

Because the installation site of online ammonia nitrogen instrument is different, mathematical model then need to calculate ammonia nitrogen concentration from the front end of aerobic section be reduced to its 2/3 aeration rate needed and from aerobic section 2/3 to aerobic section end needed for aeration rate, and through conversion, final respectively with the dissolved oxygen DO setting value needed for aerobic section 1, and the dissolved oxygen DO setting value needed for aerobic section 2 exports.

With existing accurate aeration system general rule of thumb by manual type set dissolved oxygen DO setting value unlike, ammonia control system of the present invention carries out the setting of resolving in dynamic state oxygen according to the change of water inlet factor, environmental factor and technology controlling and process target, to meet the requirement up to standard of water outlet ammonia nitrogen.

Particularly, the resolving in dynamic state oxygen setting of ammonia control system of the present invention, can be realized by artificial dynamic time sequence and these two kinds of modes full-automatic.

Wherein, artificial dynamic time sequence setting is the dissolved oxygen DO setting sequence by manually providing in the water inlet cycle, mathematical model is according to this dissolved oxygen DO setting sequence, utilize the functional relation set up, realize the dynamic setting of each dissolved oxygen DO, a general water inlet cycle is 24 hours, and a water inlet cycle can be divided into multiple period; As shown in Figure 5, the format sample figure of the dissolved oxygen value set for artificial dynamic time sequence mode.

As shown in Figure 6, it is full automatic dissolved oxygen DO setup control, is based on water inlet, goes out water condition, as operating modes such as amount of inlet water, influent COD, influent ammonium concentration, water outlet COD, water outlet ammonia nitrogen concentrations, provide the dissolved oxygen DO setting value of each dissolved oxygen DO control zone in real time.

Operation due to whole sewage treatment plant is constantly change and refreshes, thus in the dynamic setting controller of dissolved oxygen DO, a dynamic strategy is set, the dynamic setting controller of dissolved oxygen DO is according to this dynamic strategy dynamic conditioning dissolved oxygen DO setting value, otherwise there will be owing to responding not in time, bring impact can to technique and water outlet.

As for the dissolved oxygen value of aerobic section in the above-mentioned Fig. 2 of full-automatic setup control, if the reading of the second online ammonia nitrogen instrument is higher than the ammonia nitrogen setting value at line place up to standard, as shown in the curve 3 in figure, then improve the dissolved oxygen DO setting value of aerobic section 2 according to dynamic strategy; If the second online ammonia nitrogen instrument reading is lower than the ammonia nitrogen setting value at line place up to standard, as shown by curve 1, then the dissolved oxygen DO setting value of aerobic section 2 is reduced.

Core algorithm of the present invention is the same with existing accurate aeration system, all the activated sludge model ASM series proposed based on international water association (IWA), for processes such as the organic matter degradation in quantitative description biochemical wastewater treatment, nitrated, denitrification and dephosphorization.

Ammonia control system of the present invention can gather the relevant mass data of sewage treatment process, and carries out pre-service computing to all these data, comprises filtering, noise reduction etc. and rationalizes process, make the data of collection corresponding with actual condition; Analyze according to the front end ammonia nitrogen instrument measured data of aerobic section again, founding mathematical models, real setting dissolved oxygen DO setting value time dynamic, dissolved oxygen controller is according to dissolved oxygen DO setting value and actual measurement dissolved oxygen value, control to export and make ammonia nitrogen in reaction tank reach aerate flux needed for desired value, as the air demand of the corresponding control module of system.

For the algorithm of the target set point of the dissolved oxygen DO of aerobic section 1, sketch its Computing Principle:

The material balance equation of ammonia nitrogen is set up by ASM model:

$\frac{{\mathrm{dS}}_{\mathrm{NH}4}}{\mathrm{dt}}=Q_{\mathrm{in}}\frac{S_{\mathrm{NH}4,\mathrm{in}}}{V}-Q_{\mathrm{Out}}\frac{S_{\mathrm{NH}4}}{V}+Q_R\frac{S_{\mathrm{NH}4,R}}{V}-$

$\left[(1-f_{S_I})\right]\·i_{N,S_F}+f_{S_I}\·i_{N,S_I}-i_{N,X_S}](K_h\frac{S_{O2}}{K_{O2}+S_{O2}}$

$\·\frac{X_S/X_H}{K_X+X_S/X_H}\·X_H+K_h\·{\mathrm{\η}}_{\mathrm{NO}3}\·\frac{K_{O2}}{K_{O2}+S_{O2}}\·\frac{S_{\mathrm{NO}3}}{K_{\mathrm{NO}3}+S_{\mathrm{NO}3}}$

$\·\frac{X_S/X_H}{K_X+X_S/X_H}\·X_H+K_h\·{\mathrm{\η}}_{\mathrm{fe}}\·\frac{K_{O2}}{K_{O2}+S_{O2}}\·\frac{K_{\mathrm{NO}3}}{K_{\mathrm{NO}3}+S_{\mathrm{NO}3}}$

$\·\frac{X_S/X_H}{K_X+X_S/X_H}\·X_H)+(\frac{i_{N,S_F}}{Y_H}-i_{N,\mathrm{BM}})({\mathrm{\μ}}_H\frac{S_{O_2}}{K_{O_2}+S_{O_2}}$

$\·\frac{S_F}{K_F{+S}_F}\·\frac{S_F}{S_F+S_A}\·\frac{S_{\mathrm{NH}4}}{K_{{\mathrm{NH}}_4}+S_{{\mathrm{NH}}_4}}\·\frac{S_{\mathrm{PO}4}}{K_P+S_{\mathrm{PO}4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}$

$\·X_H+{\mathrm{\μ}}_H\·{\mathrm{\η}}_{\mathrm{NO}3}\·\frac{K_{O_2}}{K_{O_2}+S_{O_2}}\frac{S_F}{K_F{+S}_F}\·\frac{S_F}{S_F+S_A}\·\frac{S_{\mathrm{NH}4}}{K_{\mathrm{NH}4}+S_{\mathrm{NH}4}}$

$\·\frac{S_{\mathrm{NO}3}}{K_{\mathrm{NO}3}+S_{\mathrm{NO}3}}\·\frac{S_{\mathrm{PO}4}}{K_P+S_{\mathrm{PO}4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H)+(-i_{N,\mathrm{BM}})$

${(\mathrm{\μ}}_H\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_A}{K_A{+S}_A}\·\frac{S_A}{S_F+S_A}\·\frac{S_{\mathrm{NH}4}}{K_{\mathrm{NH}4}+S_{\mathrm{NH}4}}\·\frac{S_{\mathrm{PO}4}}{K_P+S_{\mathrm{PO}4}}$

$\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H+{\mathrm{\μ}}_H\·{\mathrm{\η}}_{\mathrm{NO}3}\·\frac{K_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_A}{K_A{+S}_A}\·\frac{S_A}{S_F+S_A}$

$\·\frac{S_{\mathrm{NH}4}}{K_{\mathrm{NH}4}+S_{\mathrm{NH}4}}\·\frac{S_{\mathrm{NO}3}}{K_{\mathrm{NO}3}+S_{\mathrm{NO}3}}\·\frac{S_{\mathrm{PO}4}}{K_P+S_{\mathrm{PO}4}}\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H)$

$i+i_{N,\mathrm{SF}}\·q_{\mathrm{fe}}\·\frac{K_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{K_{\mathrm{NO}3}}{K_{\mathrm{NO}3}+S_{\mathrm{NO}3}}\·\frac{S_F}{K_{\mathrm{fe}}+S_F}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H$

$+[i_{N,\mathrm{BM}}-i_{N,X_I}\·f_{X_I}-i_{N,X_S}\·(1-f_{X_I})]\·b_H{X}_H+(-i_{N,\mathrm{BM}}){\mathrm{\μ}}_{\mathrm{PAO}}$

$\·\frac{S_{\mathrm{NH}4}}{K_{\mathrm{NH}4}+S_{\mathrm{NH}4}}\·\frac{S_{\mathrm{PO}4}}{K_P+S_{\mathrm{PO}4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·\frac{X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}{K_{\mathrm{PHA}}+X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}$

$\·X_{\mathrm{PAO}}(\frac{S_{O_2}}{K_{O_2}+S_{O_2}}+{\mathrm{\η}}_{{\mathrm{NO}}_3}\frac{K_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_{{\mathrm{NO}}_3}}{K_{{\mathrm{NO}}_3}+S_{{\mathrm{NO}}_3}})$

In this equation, all variablees and parameter are all derived from the ASM model that international water association (IWA) proposes, wherein Q _in, Q _outbe flow of inlet water, water flow, V is the useful volume of reactor, S _nH4, _inrepresent influent ammonium concentration, namely the first ammonia nitrogen instrument monitor the ammonia nitrogen concentration of the aerobic section starting point obtained, S _nH4represent the ammonia nitrogen target set point of installation second ammonia nitrogen instrument position (i.e. aerobic section 1/2 ~ 3/4 region), S _o2represent dissolved oxygen concentration, i.e. the dissolved oxygen DO target set point of aerobic section 1.

Due to S _nH4representative ammonia nitrogen target set point is a constant, and therefore corresponding differential term is zero, and the differential equation above-mentioned is thus reduced to a nonlinear algebraic equation, thus solves and obtain S _o2, i.e. dissolved oxygen DO target setting value.

After solving the target set point obtaining dissolved oxygen DO, the aeration rate maintained under current flow condition needed for this dissolved oxygen concentration desired value can be calculated on this basis by Henry mass transfer law and ASM model:

$\mathrm{Qair}=\frac{\mathrm{Vol}\×S_{\mathrm{Sat}}\×\mathrm{delta}[-\frac{Q({\mathrm{DO}}_{\mathrm{in}}-{\mathrm{DO}}_{\mathrm{set}})}{\mathrm{Vol}}-{\left(\frac{\mathrm{dDO}}{\mathrm{dt}}\right)}_r]}{\mathrm{\α}\×{\mathrm{\θ}}^{T-20}\×\mathrm{sote}\×\mathrm{CF}\×({\mathrm{DO}}_{\mathrm{sat}}-\mathrm{DO})}$

Wherein, Qair: aeration rate, DOset: dissolved oxygen DO target set point, α: the characteristic coefficient of sewage, the oxygen transfer effect in sewage is made to be different from clear water, sote: the oxygen transfer rate under mark state, CF: conversion coefficient, for calculating the oxygen content under mark state in air, DOsat: the saturated dissolved oxygen concentration of calibrating through water quality, the depth of water, Vol: reactor volume, under Ssat:20 degree, dissolved oxygen DO is in the saturation concentration on clear water surface, delta: the coefficient after the aerator degree of depth corrects, Θ: temperature correction coefficient, T: the water temperature under field condition, wherein:

${\left(\frac{\mathrm{dDO}}{\mathrm{dt}}\right)}_r=-(1-\frac{1}{Y})({\mathrm{\μ}}_H\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_F}{K_F+S_F}\·\frac{S_F}{S_F+S_A}\·\frac{S_{{\mathrm{NH}}_4}}{K_{{\mathrm{NH}}_4}+S_{{\mathrm{NH}}_4}}\·\frac{S_{{\mathrm{PO}}_4}}{K_P+S_{{\mathrm{PO}}_4}}\·$

$\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H+{\mathrm{\μ}}_H\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_A}{K_A{+S}_A}\·\frac{S_A}{S_F+S_A}\·\frac{S_{{\mathrm{NH}}_4}}{K_{{\mathrm{NH}}_4}+S_{{\mathrm{NH}}_4}}\·\frac{S_{{\mathrm{PO}}_4}}{K_P+S_{{\mathrm{PO}}_4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_H)-$

$Y_{\mathrm{PHA}}(q_{\mathrm{PP}}\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\frac{S_{{\mathrm{PO}}_4}}{K_{\mathrm{PS}}+S_{{\mathrm{PO}}_4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·\frac{X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}{K_{\mathrm{PHA}}+X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}\frac{K_{\max }-X_{\mathrm{PP}}/X_{\mathrm{PAO}}}{K_{\mathrm{IPP}}+K_{\max }-X_{\mathrm{PP}}/X_{\mathrm{PAO}}}{X}_{\mathrm{PAO}})+$

$(1-\frac{1}{Y_H})({\mathrm{\μ}}_{\mathrm{PAO}}\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_{{\mathrm{NH}}_4}}{K_{{\mathrm{NH}}_4}+S_{{\mathrm{NH}}_4}}\frac{S_{{\mathrm{PO}}_4}}{K_P+S_{{\mathrm{PO}}_4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·\frac{X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}{K_{\mathrm{PHA}}+X_{\mathrm{PHA}}/X_{\mathrm{PAO}}}{X}_{\mathrm{PAO}})-$

$\frac{4.57-Y_A}{Y_A}{\mathrm{\μ}}_{\mathrm{AUT}}\frac{S_{O_2}}{K_{O_2}+S_{O_2}}\·\frac{S_{{\mathrm{NH}}_4}}{K_{{\mathrm{NH}}_4}+S_{{\mathrm{NH}}_4}}\·\frac{S_{{\mathrm{PO}}_4}}{K_P+S_{{\mathrm{PO}}_4}}\·\frac{S_{\mathrm{ALK}}}{K_{\mathrm{ALK}}+S_{\mathrm{ALK}}}\·X_{\mathrm{AUT}}$

represent the biochemical kinetics reaction rate of dissolved oxygen DO.S in formula _o2be numerically equal to dissolved oxygen DO desired value, other parameter and variable are all derived from ASM model.

Present invention further teaches a kind of ammonia control method in sewage biological treatment technique, as shown in figure 11, comprise the following steps:

The first step, measures the ammonia nitrogen actual value in sewage reaction tank by ammonia nitrogen instrument;

Second step, by means of mathematical model, dynamically sets dissolved oxygen DO setting value according to ammonia nitrogen actual value and the ammonia nitrogen desired value that arranged;

3rd step, measures the dissolved oxygen DO actual value in sewage reaction tank by dissolved oxygen sensing instrument;

4th step, dissolved oxygen controller reaches the aeration rate needed for desired value according to dissolved oxygen DO setting value and the dissolved oxygen DO actual value ammonia nitrogen controlled in sewage reaction tank.

Below for the Sewage Plant of certain application ammonia control system of the present invention, the specific embodiment of the present invention is described.

The technological process of this sewage treatment plant as shown in Figure 7, the sewage in sewer line by grid coarse filtration, the suspension of bulk and floating foreign material in filtered water; The sand that segregation ratio anharmonic ratio is larger in sand basin afterwards and other impurity particles; Then enter the anaerobism section in reaction tank, anoxic section and aerobic section successively, air blast machine room carries out aeration to sand basin and aerobic section, removes the organism in sewage by biochemical reaction; Be separated water outlet and mud through settling basin again, after eventually passing the techniques such as sterilization, make the water after processing meet effluent index, finally discharge the water processed.

The biochemistry pool of this Sewage Plant has four groups of parallel reactor ponds, be respectively E, F, G and H reaction tank, the design residence time of the anaerobism section in every group reaction pond, anoxic section and aerobic section is respectively 1.55h, 3.1h, 10.85h, and inside and outside reflux ratio is respectively 300%, 100%.This factory is before application ammonia control system of the present invention, and the existing accurate aeration system of steady implementation, effluent quality, pollutant fluxes and energy-saving and cost-reducing effect be all comparatively remarkable.With the G group reaction pond of this factory for pilot, carry out the transformation of ammonia control system.

Compared with the ammonia control scheme on basis, except installing except ammonia nitrogen instrument at oxygen-starved area end and rear portion, aerobic zone, the present embodiment is newly-increased 1 online ammonia nitrogen instrument AN2 at the middle part of G group reaction pond aerobic section, concrete layout is as shown in 8 figure, online ammonia nitrogen instrument AN1, AN2, AN3 represent three ammonia nitrogen instrument that reaction tank is installed along journey, aerobic section is divided into 2 different dissolved oxygen DO control zones by three ammonia nitrogen instrument, in each dissolved oxygen DO control zone, a dissolved oxygen sensing instrument is installed, dissolved oxygen sensing instrument DO305 and DO306 as shown in Figure 8.

Manually to dynamically arrange dissolved oxygen DO setting value, the control of dissolved oxygen DO and water outlet ammonia nitrogen quality achieves Expected Results:

As shown in Figure 9, be respectively the contrast waveform schematic diagram of the dissolved oxygen DO setting value of dissolved oxygen sensing instrument DO305 and DO306 and the dissolved oxygen DO actual value of actual measurement, as seen from the figure, the present invention controls dissolved oxygen value in water near target set point.

As shown in Figure 10, be the ammonia nitrogen actual value that 3 ammonia nitrogen instrument record respectively, as seen from the figure, ammonia nitrogen instrument aerobic section setting position more backward, the ammonia nitrogen actual value recorded is less.Ammonia control system of the present invention can the arbitrary setting value of ammonia control in aeration tank between 0.5 ~ 20.0mg/L, control accuracy setting value ± 0.5mg/L within the scope of, to meet in aerobic section in zones of different the different requirements of ammonia nitrogen concentration.

Technology contents of the present invention and technical characteristic have disclosed as above; but those of ordinary skill in the art still may do all replacement and the modification that do not deviate from spirit of the present invention based on teaching of the present invention and announcement; therefore; scope should be not limited to the content that embodiment discloses; and various do not deviate from replacement of the present invention and modification should be comprised, and contained by present patent application claim.

Claims (10)

1. the ammonia control system in a sewage biological treatment technique, it is characterized in that, described ammonia control system comprises mathematical model, dissolved oxygen controller, controlled aerator and sewage reaction tank, be provided with dissolved oxygen sensing instrument and ammonia nitrogen measuring instrument in described sewage reaction tank, the ammonia nitrogen actual value in reaction tank measured by described ammonia nitrogen tester, described mathematical model is according to the ammonia nitrogen desired value of described ammonia nitrogen actual value and setting, and the ammonia nitrogen in setting reaction tank reaches the dissolved oxygen DO setting value of desired value; Described dissolved oxygen sensing instrument records the dissolved oxygen DO actual value in reaction tank, and described dissolved oxygen controller exports according to described dissolved oxygen DO setting value and the described controlled aerator of dissolved oxygen DO actual value control and ammonia nitrogen can be made to reach the tolerance of desired value in reaction tank.

2. the ammonia control system in sewage biological treatment technique according to claim 1, it is characterized in that, described ammonia nitrogen measuring instrument comprises the first online ammonia nitrogen instrument and the second online ammonia nitrogen instrument, described first online ammonia nitrogen instrument is arranged on the front end of sewage reaction tank aerobic section, for measuring the ammonia nitrogen actual value of aerobic section front end; Described second online ammonia nitrogen instrument is arranged on sewage reaction tank aerobic section 1/2 ~ 3/4 place from front to back, for measuring the ammonia nitrogen actual value at aerobic section 1/2 ~ 3/4 place.

3. the ammonia control system in sewage biological treatment technique according to claim 1, is characterized in that, described ammonia control system dynamically sets described dissolved oxygen DO setting value.

4. the ammonia control system in sewage biological treatment technique according to claim 3, is characterized in that, described ammonia control system dynamically sets described dissolved oxygen DO setting value by artificial dynamic time sequence or full-automatic mode.

5. the ammonia control system in sewage biological treatment technique according to claim 4, it is characterized in that, described artificial dynamic time sequence mode is by manually providing the dissolved oxygen DO setting sequence in the water inlet cycle, described ammonia control system, according to described dissolved oxygen DO setting sequence, realizes the dynamic setting of dissolved oxygen DO setting value.

6. the ammonia control system in sewage biological treatment technique according to claim 4, is characterized in that, described full-automatic mode be described ammonia control system according to the water inlet in reaction tank, go out water condition, set out dissolved oxygen DO setting value in real time.

7. the ammonia control method in sewage biological treatment technique, reaches the aeration rate needed for desired value for the ammonia nitrogen accurately controlled in sewage reaction tank, it is characterized in that, comprising:

Measure the ammonia nitrogen actual value in sewage reaction tank;

Dissolved oxygen DO setting value is dynamically set according to described ammonia nitrogen actual value and the ammonia nitrogen desired value that arranged;

Measure the dissolved oxygen DO actual value in sewage reaction tank;

The aeration rate needed for desired value is reached according to described dissolved oxygen DO setting value and the dissolved oxygen DO actual value ammonia nitrogen controlled in sewage reaction tank.

8. the ammonia control method in sewage biological treatment technique according to claim 7, is characterized in that, the mode of described dynamic setting dissolved oxygen DO setting value is artificial dynamic time sequence mode or full-automatic mode.

9. the ammonia control method in sewage biological treatment technique according to claim 8, it is characterized in that, described artificial dynamic time sequence mode is the dissolved oxygen DO setting sequence by manually providing in the water inlet cycle, according to described dissolved oxygen DO setting sequence, realize the dynamic setting of dissolved oxygen DO setting value.

10. the ammonia control method in sewage biological treatment technique according to claim 8, is characterized in that, described full-automatic mode is according to the water inlet in reaction tank, goes out water condition, sets out dissolved oxygen DO setting value in real time.