CN113415887A - Biological enhanced denitrification device and application - Google Patents
Biological enhanced denitrification device and application Download PDFInfo
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- CN113415887A CN113415887A CN202110978025.9A CN202110978025A CN113415887A CN 113415887 A CN113415887 A CN 113415887A CN 202110978025 A CN202110978025 A CN 202110978025A CN 113415887 A CN113415887 A CN 113415887A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/006—Regulation methods for biological treatment
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/30—Aerobic and anaerobic processes
- C02F3/302—Nitrification and denitrification treatment
- C02F3/303—Nitrification and denitrification treatment characterised by the nitrification
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F3/00—Biological treatment of water, waste water, or sewage
- C02F3/30—Aerobic and anaerobic processes
- C02F3/302—Nitrification and denitrification treatment
- C02F3/305—Nitrification and denitrification treatment characterised by the denitrification
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F7/00—Aeration of stretches of water
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/04—Oxidation reduction potential [ORP]
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/22—O2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W10/00—Technologies for wastewater treatment
- Y02W10/10—Biological treatment of water, waste water, or sewage
Abstract
The invention belongs to the field of wastewater treatment, and particularly relates to a biological enhanced denitrification device and application thereof. The device comprises a wastewater pool, a biochemical pool and a sedimentation pool which are communicated in sequence; the biochemical tank comprises an anoxic aeration tank, a fluctuation tank and an aerobic aeration tank which are sequentially communicated; ORP sensors are arranged in the anoxic aeration tank and the fluctuation tank; a DO sensor is arranged in the aerobic aeration tank; the anoxic aeration tank, the fluctuation tank and the aerobic aeration tank are all provided with aeration heads; each aeration head is respectively communicated with an aeration main pipeline through an aeration branch; the invention researches that the sewage treatment system realizes the automatic adjustment of ORP/DO control parameters at different reaction stages of anoxic aeration through the automatic control of the system; ensuring the effluent quality of the biochemical system.
Description
Technical Field
The invention belongs to the field of wastewater treatment, and particularly relates to a biological enhanced denitrification device and application thereof.
Background
The biological treatment of sewage and waste water is a most economical and practical process for treating sewage and waste water, which takes the pollutants contained in the sewage and waste water as nutrient sources and utilizes the metabolism of microorganisms to degrade the pollutants, so that the sewage and waste water can be purified. The removing objects of the biological treatment of the sewage and the wastewater are mainly BOD, COD and NH3N, TN and TP, wherein the denitrification efficiency is an important index for judging the operation effect of the biological treatment process at present.
A variety of sewage biological treatment processes are available, such as A2O, an oxidation ditch, SBR, MBBR and the like, and how to reduce the tank capacity requirement and save energy consumption is an important consideration for selecting sewage and wastewater treatment processes on the premise of ensuring the treatment effect. The BNR biological enhanced denitrification process is an efficient sewage biochemical treatment process which can be selected by sewage and wastewater treatment plants, and has the advantages of saving tank capacity and energy. However, at present, there is no device and method for controlling the OPR value and the OD value in different tanks to enable the wastewater to reasonably carry out biochemical reaction denitrification so as to achieve the purpose of wastewater treatment.
Disclosure of Invention
The invention aims to provide a biological enhanced denitrification device and application thereof.
In order to achieve the purpose, the invention adopts the following technical scheme:
a biological enhanced denitrification device comprises a wastewater tank, a biochemical tank and a sedimentation tank which are communicated in sequence; the biochemical tank comprises an anoxic aeration tank, a fluctuation tank and an aerobic aeration tank which are sequentially communicated; ORP sensors are arranged in the anoxic aeration tank and the fluctuation tank; a DO sensor is arranged in the aerobic aeration tank; the anoxic aeration tank, the fluctuation tank and the aerobic aeration tank are all provided with aeration heads; each aeration head is respectively communicated with an aeration main pipeline through an aeration branch; each aeration branch is provided with an air flow meter and an aeration valve.
Under the condition that an anoxic ORP (hereinafter abbreviated as ORP 1) probe in an anoxic aeration tank detects limited aeration, the utilization condition of microorganisms in the tank on dissolved oxygen is controlled by the anoxic aeration valve on an anoxic aeration branch connected with the anoxic aeration tank, so that the ORP control range is from-200 mV to-50 mV;
the fluctuation ORP (hereinafter referred to as ORP 2) probe in the fluctuation pool detects the utilization condition of dissolved oxygen by microorganisms in the fluctuation pool under the condition of water quality fluctuation, and the aeration rate is controlled by the fluctuation aeration valve on the fluctuation aeration branch connected with the fluctuation pool, so that the ORP control range is from-50 mV to 50 mV;
an aerobic DO (DO 3) probe in the aerobic aeration tank detects the utilization condition of microorganisms in the aerobic aeration tank to dissolved oxygen, and the aeration rate is controlled through an aerobic aeration valve on an aerobic aeration branch connected with the aerobic aeration tank, so that the DO control range is 1.5mg/L to 2 mg/L.
The anoxic aeration tank is connected with the wastewater tank through a water inlet pipeline; the water inlet pipeline is provided with a water inlet pump and a flow meter.
The invention also comprises an application of the biological enhanced denitrification device, which is applied to biological enhanced denitrification and specifically comprises the following steps:
(1) starting a water inlet pump to feed water, measuring the water inflow through a flowmeter, and pumping the wastewater in the wastewater tank into a biochemical tank after the system is started;
(2) the aeration branch roads are provided with air flow meters and aeration valve control aeration rates;
under the condition that an anoxic ORP probe in the anoxic aeration tank detects restrictive aeration, the utilization condition of microorganisms in the tank on dissolved oxygen is controlled by the anoxic aeration valve on an anoxic aeration branch connected with the anoxic aeration tank, so that the ORP control range is from-200 mV to-50 mV; the fluctuation ORP probe in the fluctuation pool detects the utilization condition of dissolved oxygen by microorganisms in the fluctuation pool under the condition of water quality fluctuation, and the aeration quantity is controlled by the fluctuation aeration valve on the fluctuation aeration branch connected with the fluctuation pool, so that the ORP control range is from-50 mV to 50 mV;
detecting the utilization condition of microorganisms in the aerobic aeration tank to dissolved oxygen by an aerobic DO probe in the aerobic aeration tank, and controlling the aeration rate by an aerobic aeration valve on an aerobic aeration branch connected with the aerobic aeration tank to enable the DO control range to be 1.5mg/L to 2 mg/L;
because the quality of the inlet water is continuously fluctuated, the processes of correcting the set value and adjusting the aeration quantity are carried out in a linkage way through the detection of the anoxic ORP probe, the fluctuation ORP probe and the aerobic DO probe, the process is continuously circulated and repeated along with the fluctuation of the ORP value of the inlet water, and the ORP and DO set values and the aeration quantity of each pool are adjusted to be optimal;
(3) the effluent of the biochemical tank enters a sedimentation tank for sludge-water separation; sludge is returned or partially used as a residual sludge valve to be discharged intermittently by a sludge pump; the sludge concentration of the system is ensured to be 3000mg/L-4000mg/L, and all indexes of the effluent of the sedimentation tank are detected to meet the discharge requirement.
Specifically, the process of correcting the set value and adjusting the aeration rate is carried out in a linkage manner through the detection of an anoxic ORP probe, a fluctuation ORP probe and an aerobic DO probe in the step (2), and the method specifically comprises the following steps:
firstly, establishing an initial anoxic ORP set value, a fluctuation ORP set value and an aerobic DO set value, and providing the initial anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value as input conditions to a PID control module, wherein the PID control module compares the anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value with an actual anoxic ORP measurement value, a fluctuation ORP measurement value and an aerobic DO measurement value respectively;
the control range of an initial anoxic ORP set value is-200 mV to-50 mV, the control range of a fluctuation ORP set value is-50 mV to 50mV, and the control range of an aerobic DO set value is 1.5mg/L to 2 mg/L;
respectively measuring by an anoxic ORP probe, a fluctuation ORP probe and an aerobic DO probe, wherein the PID control module generates output which corresponds to the change or deviation of the measured value of the oxygen ORP probe and the fluctuation ORP probe relative to the set value of the oxygen ORP probe and the fluctuation ORP probe on one hand and the change or deviation of the measured value of the aerobic DO relative to the set value of the aerobic DO on the other hand;
the PID control module outputs and generates a control signal, and the control signal is used for controlling the opening of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve; the relation between the control signal and the output signal of the PID control module is a linear relation or a nonlinear relation;
feedback output values of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve are used as input of the sliding average function module; the output of the sliding average function module is compared with feedback signals of an anoxic aeration valve, a fluctuation aeration valve and an aerobic aeration valve;
the comparator receives an input signal A representing valve feedback and an input signal B representing the processing of a moving average function; the comparator generates and outputs a value representing the difference between the input value a and the input value B; the output value generated by the comparator is taken as the input value of the absolute value function; the absolute value function generates the absolute value of the change, i.e., the absolute value of the difference between input value a and input value B; the output value of the absolute value function is provided to the C branch and the E branch simultaneously.
The subsequent comparator in the branch C receives an absolute value representing the change, namely, the input value of the comparator is the output value processed by the absolute value function, and the input value C and the input value D representing the threshold value are input; when the input value C is larger than the input value D, the comparator is triggered to generate an output value;
triggering output as a condition for increasing the value of the first counter, wherein the action is carried out when the accumulated value of the first counter reaches a first counter threshold value within the set time of the first counter, and the reset is carried out when the accumulated value of the first counter does not reach the first counter threshold value; specifically, when the threshold is reached before the first counter resets the first counter value, the first counter outputs a condition for triggering adjustment of the ORP or DO set value; when the first counter reaches a preset time and does not reach a threshold value, resetting an output signal of the first counter and an accumulated value of the first counter so as to avoid oscillation of BNR control system parameters; the output value of the first counter is also used for resetting itself, and when the output value exists, resetting is carried out; adjusting the ORP set point by 10 millivolts as a new set point or adjusting the DO set point by 0.1mg/L as a new set point;
the input value E of the comparator in the branch E represents the absolute value of the change, namely, the input value of the comparator is the output value processed by an absolute value function, and the input value E and the input value F representing the threshold value are input from the branch E; when the input value E is larger than the input value F, the comparator triggers and generates an output value;
triggering the output as a signal for accumulating the value of the second counter, wherein the second counter is continuously accumulated until reaching the threshold value of the second counter, the input end provided for the AND gate is changed from logic high to logic low, the AND gate outputs logic low under the combined action (0 ^1=0) of the timing output logic high of the second timer and the output logic low of the second output counter, the ORP set point adjusting value is not acted, and the second counter and the second timer are reset and reset simultaneously. If the accumulated value of the second counter does not reach the set threshold value when the second timer outputs logic high at the fixed time, the input end provided by the second counter to the AND gate is still logic high, and when the second timer and the second counter act together (1 ^1=1), the AND gate outputs logic high, the ORP set point adjusting value is adjusted, and meanwhile, the second counter and the second timer are reset. The ORP set point is adjusted by increasing the ORP set point by 5 millivolts as a new set point or the DO set point is adjusted by increasing the DO set point by 0.05mg/L as a new set point. Compared with the prior art, the invention has the beneficial effects that:
in the application, the core control parameter of the BNR biological enhanced denitrification sewage treatment process is set as the oxygen supply. In normal conditions, neither the anoxic nor anaerobic zones contain dissolved oxygen, but oxygen-containing gas can still be supplied to the mixed liquor as long as the oxygen supply in the mixed liquor is equal to or less than the biological oxygen demand. The negative difference between the amount of oxygen supplied to the mixed liquor and the biological oxygen demand in the mixed liquor is generally referred to as an oxygen deficient state. The anoxic state caused by the unbalanced oxygen supply and demand of the mixed liquid in the pool can create an anoxic aeration condition, and simultaneously carry out nitrification and denitrification. The process of sewage treatment under such an oxygen deficient state is an anoxic aeration sewage treatment process.
The invention researches the automatic control of a sewage treatment system through the systemAnd realizes the automatic adjustment of ORP/DO control parameters at different reaction stages of anoxic aeration. Different process requirements correspond to different ORP ranges, wherein the wastewater sequentially passes through an anoxic aeration tank, a fluctuation tank and an aerobic aeration tank; the ORP control range of the anoxic aeration tank is-200 mV to-50 mV, and in the range, the degradation of organic matters, the nitrification, the denitrification and the synchronous denitrification occur, and partial short-range denitrification, NH are also accompanied4 +→NO2 -→NO3 -→NO2 -→N2The synchronous nitrification and denitrification of the 5-step denitrification can also occur: NH (NH)4 +→NO2 -→N23, short-range denitrification of denitrification; through the reaction, organic matters and ammonia nitrogen in water are removed in a large quantity;
the ORP control range of the fluctuation pool is-50 mV to 50mV, organic matters are further removed, nitrification and partial denitrification reaction are carried out, the operation condition is adjusted according to the water quality condition, the degraded organic matters and ammonia nitrogen which are not available in the anoxic aeration tank are degraded, and the integral aeration tank still belongs to the micro anoxic environment and partially carries out denitrification reaction;
the DO control range of the aerobic aeration tank is 1.5mg/L to 2mg/L, and the DO is used as a fine treatment area of aerobic reaction to ensure the effluent quality of a biochemical system.
The present application adjusts BNR control parameters by programming the oxidation-reduction potential (ORP) and Dissolved Oxygen (DO) setpoints. An ORP electrode is one that can take up or release electrons at the surface of its sensitive layer. The sensing layer itself is made of an inert metal, typically platinum or gold, and its reference electrode is a silver/silver chloride electrode identical to the pH electrode, and the ORP value can be obtained by measuring the potential difference between the inert indicator electrode and the reference electrode. Thus, the present invention adjusts the ORP set point in response to the adjustment of at least one BNR control parameter, which in this example is selected as the core control parameter oxygen supply. The control considers the change of the ORP measurement value of the mixed liquid caused by the change of the conditions in the BNR wastewater treatment process and the characteristics of time-varying property, nonlinearity, multivariable and the like in the biological wastewater treatment process, and optimizes the reliability and the efficiency of the BNR wastewater treatment process by predicting and adjusting the operating parameters through an algorithm.
Compared with the traditional control system, the BNR control system adds a moving average function for simple prediction, and the basic idea is as follows: and sequentially calculating a time-sequence average value containing a certain number of terms according to the time sequence and item-by-item transition so as to reflect the long-term trend. Therefore, the moving average method can eliminate the problems that the fluctuation is large due to the influence of periodic variation and random fluctuation, and the development trend of the data is not easy to display, so that the development direction and the trend (namely, the trend line) of the data can be displayed, and then the long-term trend of the data can be analyzed and predicted according to the trend line.
The follow-up timer and the counter are linked to form a delay control program. And the comparison result of the actual value and the predicted value is input into a time delay control program for outputting after being compared and judged with the empirical value. The added time delay control program can further effectively inhibit the oscillation in the system.
The control unit added in the system can respond to future change prediction in advance and make the system robust, so that the control system can operate stably and efficiently.
Drawings
FIG. 1 is a schematic view of the overall structure of the enhanced biological denitrification apparatus of the present invention;
FIGS. 2-3 are schematic diagrams of ORP and DO control systems, respectively;
FIGS. 4 to 6 show the water inlet and outlet indexes of COD, BOD, ammonia nitrogen, total nitrogen, nitrate nitrogen and nitrite nitrogen in the examples.
Detailed Description
In order to make the technical solutions of the present invention better understood by those skilled in the art, the present invention will be further described in detail with reference to the accompanying drawings and preferred embodiments.
A biological enhanced denitrification device comprises a wastewater tank, a biochemical tank and a sedimentation tank 13 which are communicated in sequence; the biochemical tank comprises an anoxic aeration tank 10, a fluctuation tank 11 and an aerobic aeration tank 12 which are communicated in sequence; ORP sensors are arranged in the anoxic aeration tank and the fluctuation tank; a DO sensor is arranged in the aerobic aeration tank; the anoxic aeration tank, the fluctuation tank and the aerobic aeration tank are all provided with aeration heads; each aeration head is respectively communicated with an aeration main pipeline through an aeration branch; each aeration branch is provided with an air flow meter and an aeration valve.
The anoxic aeration tank is connected with the wastewater tank through a water inlet pipeline; the water inlet pipeline is provided with a water inlet pump and a flow meter.
The invention also comprises an application of the biological enhanced denitrification device, which is applied to biological enhanced denitrification and specifically comprises the following steps:
(1) starting a water inlet pump to feed water, measuring the water inflow through a flowmeter, and pumping the wastewater in the wastewater tank into a biochemical tank after the system is started;
(2) the aeration branch roads are provided with air flow meters and aeration valve control aeration rates;
an anoxic ORP probe 1 in the anoxic aeration tank detects the utilization condition of dissolved oxygen by microorganisms in the tank under the condition of restrictive aeration, and controls the aeration quantity through an anoxic aeration valve 4 on an anoxic aeration branch connected with the anoxic aeration tank, so that the control range of ORP is from-200 mV to-50 mV; an anoxic flow meter 5 is arranged on the anoxic aeration branch;
the fluctuation ORP probe 2 in the fluctuation pool is used for detecting the utilization condition of microorganisms in the fluctuation pool to dissolved oxygen under the condition of water quality fluctuation, and the aeration quantity is controlled through a fluctuation aeration valve 6 on a fluctuation aeration branch connected with the fluctuation pool, so that the ORP control range is from-50 mV to 50 mV; a wave flow meter 7 is arranged on the wave aeration branch;
an aerobic DO probe 3 in the aerobic aeration tank detects the utilization condition of microorganisms in the aerobic aeration tank to dissolved oxygen, and an aerobic aeration valve 8 on an aerobic aeration branch connected with the aerobic aeration tank controls the aeration quantity to ensure that the DO control range is 1.5mg/L to 2 mg/L; an aerobic flowmeter 9 is arranged on the aerobic aeration branch;
the anoxic aeration tank is connected with the wastewater tank through a water inlet pipeline; the water inlet pipeline is provided with a water inlet pump 14.
Because the quality of the inlet water is continuously fluctuated, the process of correcting the set value and adjusting the aeration quantity through the control system 17 is carried out in a linkage way through the detection of the anoxic ORP probe, the fluctuation ORP probe and the aerobic DO probe, the process is continuously circulated and repeated along with the fluctuation of the ORP value of the inlet water, and the ORP and DO set values and the aeration quantity of each pool are adjusted to be optimal; a programmable controller 18 is provided on the control system.
(3) The effluent of the biochemical tank enters a sedimentation tank for sludge-water separation; the sludge is returned or partially discharged as residual sludge intermittently by a sludge pump; a stop valve 16 is arranged on the return pipeline, and a drain valve 15 is arranged on the discharge pipeline; the sludge concentration of the system is ensured to be 3000mg/L-4000mg/L, and all indexes of the effluent of the sedimentation tank are detected to meet the discharge requirement.
Specifically, the processes of correcting the set value and adjusting the aeration amount are carried out in a linkage manner through the detection of an anoxic ORP probe, a fluctuation ORP probe and an aerobic DO probe in the step (2), and the figures 2-3 are respectively schematic diagrams of an ORP control system and an DO control system;
the method specifically comprises the following steps:
firstly, establishing an initial anoxic ORP set value, a fluctuation ORP set value and an aerobic DO set value, and providing the initial anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value as input conditions to a PID control module, wherein the PID control module compares the anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value with an actual anoxic ORP measurement value, a fluctuation ORP measurement value and an aerobic DO measurement value respectively;
the control range of an initial anoxic ORP set value is-200 mV to-50 mV, the control range of a fluctuation ORP set value is-50 mV to 50mV, and the control range of an aerobic DO set value is 1.5mg/L to 2 mg/L;
respectively measuring by an anoxic ORP probe, a fluctuation ORP probe and an aerobic DO probe, wherein the PID control module generates output, and the output of the PID control module corresponds to the change or deviation of the measured value of the anoxic ORP probe and the fluctuation ORP probe relative to the set value of the anoxic ORP probe and the fluctuation ORP probe on one hand and the change or deviation of the measured value of the aerobic DO relative to the set value of the aerobic DO on the other hand;
the PID control module outputs and generates a control signal, and the control signal is used for controlling the opening of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve; the relation between the control signal and the output signal of the PID control module is a linear relation or a nonlinear relation;
feedback output values of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve are used as input of the sliding average function module; the output of the sliding average function module is compared with feedback signals of an anoxic aeration valve, a fluctuation aeration valve and an aerobic aeration valve;
the comparator receives an input signal A representing valve feedback and an input signal B representing the processing of a moving average function; the comparator generates and outputs a value representing the difference between the input value a and the input value B; the output value generated by the comparator is taken as the input value of the absolute value function; the absolute value function generates the absolute value of the change, i.e., the absolute value of the difference between input value a and input value B;
the subsequent comparator receives an absolute value representing the change, namely, the input value of the comparator is an output value processed by an absolute value function, and the input value C and the input value D represent a threshold value; when the input value C is larger than the input value D, the comparator is triggered to generate an output value;
triggering output as a condition for increasing the value of a first counter (timer 1 in the figure, the same applies below), wherein the action is carried out when the accumulated value of the first counter reaches a first counter threshold value within the set time of the first counter, and the reset is carried out when the accumulated value of the first counter does not reach the first counter threshold value; specifically, when the threshold is reached before the first counter resets the first counter value, the first counter outputs a condition for triggering adjustment of the ORP or DO set value; when the first counter reaches a preset time and does not reach a threshold value, resetting an output signal of the first counter and an accumulated value of the first counter so as to avoid oscillation of BNR control system parameters; the output value of the first counter is also used for resetting itself, and when the output value exists, resetting is carried out; adjusting the ORP set point by 10 millivolts as a new set point or adjusting the DO set point by 0.1mg/L as a new set point;
the input value E of the comparator represents the absolute value of the change, namely, the input value of the comparator is the output value processed by an absolute value function, and the input value E and the input value F represent the threshold value are input from the E; when the input value E is larger than the input value F, the comparator triggers and generates an output value;
triggering and outputting a signal used for accumulating the value of a second counter (a timer 2 in the figure, the same below), continuously accumulating the second counter until the threshold value of the second counter is reached, and negating the signal and providing the signal for an AND gate output value; if the value accumulated by the second counter reaches its set threshold before the second counter resets the counter, the AND gate output value will be provided and reset. If the accumulated value of the second counter does not reach the set threshold value before the second counter resets the counter, the counter does not generate output, and the second counter are reset; the ORP set point is adjusted by increasing the ORP set point by 5 millivolts as a new set point or the DO set point is adjusted by increasing the DO set point by 0.05mg/L as a new set point.
Specific test examples: a sewage treatment plant No. 1 adopts a BNR biological enhanced denitrification sewage treatment process, and the denitrification requirement is higher by 90 percent, so that 100 percent of mixed liquor backflow is increased in the example. The water inlet and outlet indexes of COD, BOD, ammonia nitrogen, total nitrogen, nitrate nitrogen and nitrite nitrogen are shown in figures 4-6. The original sewage plant executes the second-level discharge standard of pollutant discharge standard (GB 18918-2002) of urban sewage treatment plant, COD is less than or equal to 80mg/L, ammonia nitrogen is less than or equal to 15mg/L (water temperature is more than 12 ℃) and less than or equal to 20mg/L (water temperature is less than or equal to 12 ℃), and total nitrogen is less than or equal to 25mg/L, and the COD, the ammonia nitrogen and the total nitrogen are improved to be less than or equal to 60mg/L, less than or equal to 5mg/L (water temperature is more than 12 ℃) and less than or equal to 8mg/L (water temperature is less than or equal to 12 ℃) and less than or equal to 15mg/L after the BNR biologically enhanced denitrification sewage treatment process is adopted.
In the embodiment, the ORP1 range controlled by the anoxic aeration tank is less than or equal to-50 mv, the ORP1 set value is-70 mv, the ORP probe measurement value of the anoxic aeration tank generates output through a PID control module, the output of the PID control module corresponds to the change or deviation of the ORP probe measurement value of the anoxic tank relative to the ORP probe set value of the anoxic tank, and the PID control module outputs and generates a control signal which is used for controlling the opening degree of an aeration valve of the anoxic tank; the comparator receives a valve feedback signal A1 and a sliding average value function input signal B1, generates an input value (A1-B1) and outputs the input value (A1-B1), the input value is processed by an absolute value function and then output as a C1 value, the set value of D1 is 30, when the input value (C1> D1) is input, the accumulated value of a first counter is operated when the accumulated value of the first counter reaches a first counter threshold value within the set time of the first counter, when the first counter reaches the preset time, the threshold value is not reached, the output signal of the first counter and the accumulated value of the first counter are reset, when the output value is output, the reset is also carried out, if the ORP1 is triggered to be reduced by 10mv when the output is generated, the set value of ORP1 is adjusted to be-80 mv as a new set value; the set value of F1 is 5, the input value E1 of the comparator is the output value processed by the absolute value function, when the input value (E1> F1), the comparator triggers and generates the output value, the trigger output is continuously accumulated as the signal of the accumulated second counter value within the set time until the threshold value of the second counter is reached, the trigger is inverted and provided for the output value of the AND gate and reset, the accumulated value of the second counter does not reach the set threshold value, no output is generated, the second counter and the second counter are reset, if the trigger adjustment ORP1 is increased by 5mv when the output is generated, ORP1 is readjusted to-75 mv as a new set value.
The ORP2 range for the fluctuating pool control is: 50 mv-50 mv, wherein the ORP2 set value is 0mv, the fluctuation pool ORP probe measurement value generates output through a PID control module, the output of the PID control module corresponds to the change or deviation of the fluctuation pool ORP probe measurement value relative to the fluctuation pool ORP probe set value, and the PID control module outputs and generates a control signal which is used for controlling the opening degree of the fluctuation pool aeration valve; the comparator receives a valve feedback signal A2 and a sliding average function input signal B2, generates an input value (A2-B2) output, outputs the value as a C2 value after absolute value function processing, the set value of D2 is 30, when the input value (C2 > D2), the accumulated value of the first counter reaches the threshold value of the first counter in the set time of the first counter, the operation is carried out, when the first counter reaches the preset time, the threshold value is not reached, the output signal of the first counter and the accumulated value of the first counter are reset, when the output value is present, the reset is also carried out, when the output is generated, the ORP2 is triggered to be reduced by 10mv, the ORP2 set value is regulated to-10 mv as a new set value, the set value of F2 is 5, the input value E2 of the comparator is the output value after absolute value function processing, when the input value (E2 > F2), the comparator is triggered to generate the output value, triggering output as a signal for accumulating the value of the second counter to accumulate continuously within a set time until the signal reaches the threshold value of the second counter, negating the signal and providing the signal for the output value of the AND gate to reset, wherein the accumulated value of the second counter does not reach the set threshold value, no output is generated, the second counter and the second counter are reset, and if the ORP2 is triggered to be increased by 5mv when output is generated, the ORP2 is readjusted to be-5 mv as a new set value;
the DO3 range controlled by the aerobic aeration tank is as follows: 1.5 mg/L-2.0 mg/L, wherein the DO3 set value is 1.8mg/L, the measured value of the ORP probe of the aerobic pool generates output through a PID control module, the output of the PID control module corresponds to the change or deviation of the measured value of the ORP probe of the aerobic pool relative to the set value of the ORP probe of the aerobic pool, and the output of the PID control module generates a control signal which is used for controlling the opening degree of an aeration valve of the aerobic pool; the comparator receives the feedback signal A3 representing the valve and the input signal B3 of the sliding average function, generates an input value (A3-B3) and outputs the input value (A3-B3), and outputs the input value as a C3 value after absolute value function processing; the setting value of D3 is 0.3, when the input value (C3 > D3), the accumulated value of the first counter reaches the first counter threshold value in the first counter setting time, when the first counter reaches the preset time, the threshold value is not reached, the output signal of the first counter and the accumulated value of the first counter are reset, and when the output value exists, the reset is also carried out. If the trigger adjustment DO3 is reduced by 0.1mg/L when the output is generated, the setting value of the adjustment DO3 is 1.7mg/L as a new setting value, the setting value of the F3 is 0.05, the input value E3 of the comparator is an output value processed by an absolute value function, when the input value (E3 > F3) is input, the comparator triggers and generates an output value, the trigger output is continuously accumulated as a signal for accumulating the value of a second counter within the set time until the threshold value of the second counter (timer 2 in the figure) is reached, the trigger output is inverted and provided for the output value of the AND gate and reset, the accumulated value of the second counter does not reach the set threshold value, the output cannot be generated, the second counter and the second counter are reset, and if the trigger adjustment DO3 is increased by 0.05 when the output is generated, the adjustment DO3 is newly adjusted to 1.75mg/L as a new setting value;
the ORP/DO control system corrects a set value according to a measured value A1/A2/A3, calculates the aeration quantity of the air supply quantity adjusting system through the set value, the process is continuously circulated and repeated along with the fluctuation of the ORP/DO value of the inlet water, and the ORP/DO set value and the aeration quantity in the adjusting tank tend to be optimal;
as shown in FIG. 4, BOD of the influent water5The highest water amount can be 219.42mg/L and the lowest 147.56mg/L, and the highest water COD amount can be 483mg/L and the lowest water COD amount can be 303 mg/L. BOD of influent water5And COD both fluctuate obviously and the concentration is higher. The effluent BOD after the treatment of the system5The stability is 10.80mg/L, and the COD of the effluent is 57 mg/L. Obviously, the concentration of the treated effluent is obviously reduced and stably meets the emission requirement. As can be seen from FIG. 5, the highest total nitrogen of the inlet water is 78.15mg/L and the lowest 40.87mg/L, and the highest ammonia nitrogen of the inlet water is 50.8mg/L and the lowest 33.93 mg/L. The ammonia nitrogen and the total nitrogen of the inlet water are both at a higher level and fluctuate greatly. The total nitrogen stability of the effluent is less than or equal to 15mg/L, and the ammonia nitrogen stability of the effluent is less than or equal to 5 mg/L. Obviously, the total nitrogen and ammonia nitrogen are both obviously reduced to meet the emission requirement and the concentration is stable and hardly fluctuates. As can be seen from FIG. 6, the average value of the nitrate nitrogen of the influent water is 1.4mg/L, the average value of the nitrite nitrogen is 0.5mg/L, the nitrate nitrogen is at a lower level, and the nitrate nitrogen of the effluent water is increased to reach 6.7 mg/L. The ammonia nitrogen is converted into nitrate nitrogen and nitrite nitrogen, and the amount of the nitrite nitrogen is increased. All indexes of the total inlet water fluctuate obviously, and the outlet water keeps stable and reaches the discharge standard, so that the parameter control of the system is proved to be reasonable.
The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.
Claims (4)
1. A biological enhanced denitrification device is characterized by comprising a wastewater tank, a biochemical tank and a sedimentation tank which are communicated in sequence; the biochemical tank comprises an anoxic aeration tank, a fluctuation tank and an aerobic aeration tank which are sequentially communicated; ORP sensors are arranged in the anoxic aeration tank and the fluctuation tank; a DO sensor is arranged in the aerobic aeration tank; the anoxic aeration tank, the fluctuation tank and the aerobic aeration tank are all provided with aeration heads; each aeration head is respectively communicated with an aeration main pipeline through an aeration branch; each aeration branch is provided with an air flow meter and an aeration valve;
wherein, under the condition that an anoxic ORP probe in the anoxic aeration tank detects restrictive aeration, the utilization condition of microorganisms in the tank on dissolved oxygen is controlled by the anoxic aeration valve on an anoxic aeration branch connected with the anoxic aeration tank, so that the ORP control range is from-200 mV to-50 mV;
the fluctuation ORP probe in the fluctuation pool detects the utilization condition of dissolved oxygen by microorganisms in the fluctuation pool under the condition of fluctuation of the water quality of inlet water, and the aeration rate is controlled by the fluctuation aeration valve on the fluctuation aeration branch connected with the fluctuation pool, so that the ORP control range is from-50 mV to 50 mV;
an aerobic DO probe in the aerobic aeration tank detects the utilization condition of microorganisms in the aerobic aeration tank to dissolved oxygen, and the aeration quantity is controlled through an aerobic aeration valve on an aerobic aeration branch connected with the aerobic aeration tank, so that the DO control range is 1.5mg/L to 2 mg/L.
2. The enhanced biological nitrogen removal device as claimed in claim 1, wherein the biochemical tank is connected to the wastewater tank through a water inlet pipeline; the water inlet pipeline is provided with a water inlet pump and a flow meter.
3. The application of the biological enhanced nitrogen removal device of any one of claims 1-2, which is applied to biological enhanced nitrogen removal, specifically comprising the following steps:
(1) starting a water inlet pump to feed water, measuring the water inflow through a flowmeter, and pumping the wastewater in the wastewater tank into a biochemical tank after the system is started;
(2) the aeration branch roads are provided with air flow meters and aeration valve control aeration rates;
under the condition that an anoxic ORP probe in the anoxic aeration tank detects restrictive aeration, the utilization condition of microorganisms in the tank on dissolved oxygen is controlled by the anoxic aeration valve on an anoxic aeration branch connected with the anoxic aeration tank, so that the ORP control range is from-200 mV to-50 mV;
the fluctuation ORP probe in the fluctuation pool detects the utilization condition of dissolved oxygen by microorganisms in the fluctuation pool under the condition of water quality fluctuation, and the aeration quantity is controlled by the fluctuation aeration valve on the fluctuation aeration branch connected with the fluctuation pool, so that the ORP control range is from-50 mV to 50 mV;
detecting the utilization condition of microorganisms in the aerobic aeration tank to dissolved oxygen by an aerobic DO probe in the aerobic aeration tank, and controlling the aeration rate by an aerobic aeration valve on an aerobic aeration branch connected with the aerobic aeration tank to enable the DO control range to be 1.5mg/L to 2 mg/L;
because the quality of the inlet water is continuously fluctuated, the processes of correcting the set value and adjusting the aeration quantity are carried out in a linkage way through the detection of the anoxic ORP probe, the fluctuation ORP probe and the aerobic DO probe, the process is continuously circulated and repeated along with the fluctuation of the ORP value of the inlet water, and the ORP and DO set values and the aeration quantity of each pool are adjusted to be optimal;
(3) the effluent of the biochemical tank enters a sedimentation tank for sludge-water separation; sludge is returned or partially used as a residual sludge valve to be discharged intermittently by a sludge pump; the sludge concentration of the system is ensured to be 3000mg/L-4000mg/L, and all indexes of the effluent of the sedimentation tank are detected to meet the discharge requirement.
4. The use of the enhanced biological nitrogen removal device according to claim 3, wherein the steps (2) of correcting the set value and adjusting the aeration amount through the detection of the anoxic ORP probe, the fluctuation ORP probe and the aerobic DO probe are performed in a linkage manner, and specifically comprises the following steps:
firstly, establishing an initial anoxic ORP set value, a fluctuation ORP set value and an aerobic DO set value, and providing the initial anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value as input conditions to a PID control module, wherein the PID control module compares the anoxic ORP set value, the fluctuation ORP set value and the aerobic DO set value with an actual anoxic ORP measurement value, a fluctuation ORP measurement value and an aerobic DO measurement value respectively;
the control range of an initial anoxic ORP set value is-200 mV to-50 mV, the control range of a fluctuation ORP set value is-50 mV to 50mV, and the control range of an aerobic DO set value is 1.5mg/L to 2 mg/L;
the method comprises the steps that an anoxic ORP probe, a fluctuation ORP probe and an aerobic DO probe are used for measurement respectively, a PID control module generates output, and the output of the PID control module corresponds to the change or deviation of the measured value of the anoxic ORP probe and the fluctuation ORP probe relative to the set value of the anoxic ORP probe and the fluctuation ORP probe on one hand and the change or deviation of the measured value of the aerobic DO relative to the set value of the aerobic DO on the other hand;
the PID control module outputs and generates a control signal, and the control signal is used for controlling the opening of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve; the relation between the control signal and the output signal of the PID control module is a linear relation or a nonlinear relation;
feedback output values of the anoxic aeration valve, the fluctuation aeration valve and the aerobic aeration valve are used as input of the sliding average function module; the output of the sliding average function module is compared with feedback signals of an anoxic aeration valve, a fluctuation aeration valve and an aerobic aeration valve;
the comparator receives an input signal A representing valve feedback and an input signal B representing the processing of a moving average function; the comparator generates and outputs a value representing the difference between the input value a and the input value B; the output value generated by the comparator is taken as the input value of the absolute value function; the absolute value function generates the absolute value of the change, i.e., the absolute value of the difference between input value a and input value B;
the subsequent comparator receives an absolute value representing the change, namely, the input value of the comparator is an output value processed by an absolute value function, and the input value C and the input value D represent a threshold value; when the input value C is larger than the input value D, the comparator is triggered to generate an output value;
triggering output as a condition for increasing the value of the first counter, wherein the action is carried out when the accumulated value of the first counter reaches a first counter threshold value within the set time of the first counter, and the reset is carried out when the accumulated value of the first counter does not reach the first counter threshold value; specifically, when the threshold is reached before the first counter resets the first counter value, the first counter outputs a condition for triggering adjustment of the ORP or DO set value; when the first counter reaches a preset time and does not reach a threshold value, resetting an output signal of the first counter and an accumulated value of the first counter so as to avoid oscillation of BNR control system parameters; the output value of the first counter is also used for resetting itself, and when the output value exists, resetting is carried out; adjusting the ORP set point by 10 millivolts as a new set point or adjusting the DO set point by 0.1mg/L as a new set point;
the input value E of the comparator represents the absolute value of the change, namely, the input value of the comparator is the output value processed by an absolute value function, and the input value E and the input value F represent the threshold value are input from the E; when the input value E is larger than the input value F, the comparator triggers and generates an output value;
triggering and outputting a signal used for accumulating the value of a second counter, continuously accumulating the second counter until the threshold value of the second counter is reached, and negating the signal and providing the output value for an AND gate; if the accumulated value of the second counter reaches the set threshold value before the second counter resets the counter, the accumulated value is provided for the AND gate to output a value, and the reset is carried out; if the accumulated value of the second counter does not reach the set threshold value before the second counter resets the counter, the counter can not generate output, and the second counter are reset; the ORP set point is adjusted by increasing the ORP set point by 5 millivolts as a new set point or the DO set point is adjusted by increasing the DO set point by 0.05mg/L as a new set point.
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