An accurate aeration control system and method for MBR process

Abstract

The present invention discloses a precise aeration control system and method for MBR process, including an on-line detection system, an ammonia nitrogen-dissolved oxygen PLC control system, a dissolved oxygen-biochemical air volume PLC control system and a biochemical air volume control system; through the synergistic effect of the on-line detection system, the ammonia nitrogen-dissolved oxygen PLC control system, the dissolved oxygen-biochemical air volume PLC control system and the biochemical air volume control system, a cascade control system is constructed with the effluent ammonia nitrogen control as the target parameter and the biochemical blower air volume as the control output, replacing the traditional cascade control system with the biochemical dissolved oxygen as the target parameter and the biochemical blower air volume as the control output, so as to fully consider the further degradation effect of the MBR membrane tank on pollutants and reduce the energy consumption of biochemical aeration.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and particularly to a precise aeration control system and method for an MBR process. Background Art

[0002] The A2 / O+MBR process has become a technology that has attracted much attention and been applied on a large scale due to its high efficiency in nitrogen and phosphorus removal and good effluent quality. However, the energy consumption per ton of water in the A2 / O+MBR process is relatively high, usually in the range of 0.4 - 1.12 kW·h, and the energy consumption of biochemical aeration and membrane scrubbing aeration accounts for more than 50%.

[0003] Current research and applications mostly focus on optimizing aeration energy conservation for the A2 / O unit or the MBR unit alone, and have formed energy conservation optimization control methods such as biochemical precise aeration and membrane scrubbing intermittent aeration. The existing biochemical precise aeration control system mainly has the following two technical defects: (1) The MBR unit is both a separation unit for activated sludge mixed liquor and a pollutant degradation unit. The existing biochemical precise aeration system controls the end of the aerobic tank, that is, controls the dissolved oxygen content in front of the MBR membrane tank, and controls the degradation of organic matter and the removal of ammonia nitrogen to be completed at the end of the aerobic tank, while ignoring the further degradation effect of the MBR unit on pollutants. Therefore, the energy consumption of the biochemical aeration system is still relatively high; (2) The dissolved oxygen carried in the reflux mixed liquor from the MBR membrane tank to the aerobic tank is an important supplement to biochemical aeration. The existing biochemical precise aeration system ignores the role of this part of dissolved oxygen, resulting in a still relatively high energy consumption of the biochemical aeration system. Summary of the Invention

[0004] To solve the above two technical defects existing in the existing biochemical precise aeration system, the present invention provides a precise aeration control system and method for an MBR process.

[0005] The technical solution adopted by the present invention is as follows:

[0006] A precise aeration control system for an MBR process includes an on-line detection system, an ammonia nitrogen-dissolved oxygen PLC control system, a dissolved oxygen-biochemical air volume PLC control system, and a biochemical air volume control system;

[0007] The on-line monitoring system includes an influent flowmeter, an influent COD on-line monitor, an influent ammonia nitrogen on-line monitor arranged at the influent end of the aerobic tank, a biochemical on-line dissolved oxygen monitor arranged in the aerobic tank, an effluent ammonia nitrogen on-line monitor arranged at the water production end of the MBR membrane tank, a sludge reflux flowmeter arranged at the influent of the aerobic tank return liquid, a membrane scrubbing gas flowmeter arranged at the outlet of the membrane scrubbing fan, and a biochemical gas flowmeter arranged at the outlet of the biochemical fan;

[0008] The ammonia nitrogen-dissolved oxygen PLC control system includes an influent water quality and quantity / ammonia nitrogen feed-forward compensator and an ammonia nitrogen-dissolved oxygen controller; an influent flowmeter, an on-line influent COD monitor, and an on-line influent ammonia nitrogen monitor are respectively connected to the inlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator, and the outlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator and the on-line effluent ammonia nitrogen monitor are respectively connected to the inlet of the ammonia nitrogen-dissolved oxygen controller;

[0009] The dissolved oxygen-biochemical air volume PLC control system includes a membrane tank reflux / dissolved oxygen feed-forward compensator and a dissolved oxygen-biochemical aeration air volume controller. The on-line effluent ammonia nitrogen monitor and the on-line biochemical dissolved oxygen monitor are respectively connected to the inlet of the membrane tank reflux / dissolved oxygen feed-forward compensator. The outlet of the ammonia nitrogen-dissolved oxygen controller, the on-line biochemical dissolved oxygen monitor, and the outlet of the membrane tank reflux / dissolved oxygen feed-forward compensator are respectively connected to the inlet of the dissolved oxygen-biochemical aeration air volume controller;

[0010] The biochemical air volume control system includes a biochemical air volume controller. A biochemical gas flowmeter and the outlet of the dissolved oxygen-biochemical aeration air volume controller are respectively connected to the inlet of the biochemical air volume controller. The biochemical air volume controller is used to control the operation of the biochemical blower.

[0011] The control method of the above MBR process precise aeration control system includes the following steps:

[0012] (1) The influent flowmeter, the on-line influent COD monitor, and the on-line influent ammonia nitrogen monitor respectively collect the influent flow value, the influent chemical oxygen demand value, and the influent ammonia nitrogen value of the aerobic tank inlet water, and transmit the data to the influent water quality and quantity / ammonia nitrogen feed-forward compensator; the influent water quality and quantity / ammonia nitrogen feed-forward compensator calculates the effluent ammonia nitrogen control compensation value through the first control algorithm, and transmits the effluent ammonia nitrogen control compensation value to the ammonia nitrogen-dissolved oxygen controller;

[0013] (2) The on-line effluent ammonia nitrogen monitor collects the ammonia nitrogen value of the MBR membrane tank effluent and transmits the data to the ammonia nitrogen-dissolved oxygen controller. The ammonia nitrogen-dissolved oxygen controller combines the preset effluent ammonia nitrogen control value and the effluent ammonia nitrogen control compensation value output by the influent water quality and quantity / ammonia nitrogen feed-forward compensator, calculates the ammonia nitrogen control deviation through addition and subtraction operations, and calculates the biochemical dissolved oxygen control set value through the second control algorithm for the ammonia nitrogen control deviation;

[0014] (3) The sludge reflux flowmeter and the membrane scrubbing gas flowmeter respectively collect the sludge reflux volume of the aerobic tank and the membrane scrubbing air volume of the membrane tank, and transmit the data to the membrane tank reflux / dissolved oxygen feed-forward compensator. The membrane tank reflux / dissolved oxygen feed-forward compensator calculates the biochemical dissolved oxygen control compensation value caused by the membrane tank reflux fluctuation through the third control algorithm, and transmits the biochemical dissolved oxygen control compensation value to the dissolved oxygen-biochemical aeration air volume controller;

[0015] (4) The on-line biochemical dissolved oxygen monitor collects the dissolved oxygen value of the biochemical effluent and transmits the effluent dissolved oxygen value to the dissolved oxygen-biochemical aeration air volume controller. The dissolved oxygen-biochemical aeration air volume controller combines the biochemical dissolved oxygen control set value output by the ammonia nitrogen-dissolved oxygen controller and the biochemical dissolved oxygen control compensation value output by the membrane tank reflux / dissolved oxygen feedforward compensator, calculates the biochemical dissolved oxygen control deviation through addition and subtraction operations, and calculates the biochemical air volume control set value through the fourth control algorithm for the biochemical dissolved oxygen control deviation;

[0016] (5) The biochemical gas flowmeter collects the biochemical air volume and transmits the biochemical air volume to the biochemical air volume controller. The biochemical air volume controller combines the biochemical air volume control set value output by the dissolved oxygen-biochemical air volume controller, calculates the biochemical air volume control deviation through addition and subtraction operations, and adjusts the output air volume of the biochemical blower according to the biochemical air volume control deviation.

[0017] Further, the first control algorithm is:

[0018]

[0019] Where:

[0020] L N is the effluent ammonia nitrogen control compensation value, mg / L;

[0021] Q i is the actual influent flow value transmitted by the influent flowmeter, m 3 / h;

[0022] Q d is the designed influent flow value, m 3 / h;

[0023] COD i is the actual influent chemical oxygen demand value transmitted by the influent COD on-line monitor, mg / L;

[0024] COD d is the designed influent chemical oxygen demand value, mg / L;

[0025] (NH3-N) i is the actual influent ammonia nitrogen value transmitted by the influent ammonia nitrogen on-line monitor, mg / L;

[0026] (NH3-N) d is the designed influent ammonia nitrogen value, mg / L;

[0027] (NH3-N)0 is the effluent ammonia nitrogen control set value, mg / L;

[0028] K2 is the influent water quality and quantity / ammonia nitrogen dynamic compensation coefficient, and the value-taking method is as follows:

[0029] If If there is a term equal to 1 in it, this term is excluded from the value calculation formula, and the remaining terms are used for value calculation;

[0030]

[0031] K3 is the deviation coefficient of influent water quality / ammonia nitrogen, and its value is 2.

[0032] Furthermore, the ammonia nitrogen control deviation is:

[0033] δ N =(NH3-N)0-(NH3-N) e +L N

[0034] Where:

[0035] δ N is the ammonia nitrogen control deviation, mg / L;

[0036] (NH3-N)0 is the set value of effluent ammonia nitrogen control, mg / L;

[0037] (NH3-N) e is the actual effluent ammonia nitrogen value transmitted by the effluent ammonia nitrogen on-line monitor, mg / L;

[0038] L N is the compensation value of effluent ammonia nitrogen control, mg / L.

[0039] Furthermore, the second control algorithm is:

[0040]

[0041] Where:

[0042] DO t is the set value of biochemical dissolved oxygen control at time t, mg / L;

[0043] DO0 is the set value of biochemical dissolved oxygen control at time 0, mg / L;

[0044] Kp1 is the ammonia nitrogen proportional coefficient, and its value is 0-5;

[0045] K i1 is the ammonia nitrogen integral coefficient, and its value is 0-0.1min -1 ;

[0046] δ N is the ammonia nitrogen control deviation, mg / L;

[0047] t is the integral period, and its value is 15min.

[0048] Furthermore, the set value of effluent ammonia nitrogen control is:

[0049] (NH3-N)0 = K1(NH3-N)s

[0050] Where:

[0051] (NH3-N)0 is the set value of the effluent ammonia nitrogen control, mg / L;

[0052] (NH3-N)s is the limit value of the effluent ammonia nitrogen set by the industry emission standard, mg / L;

[0053] K1 is the safety factor, and K1 ∈ (0, 1).

[0054] Furthermore, the third control algorithm is as follows:

[0055]

[0056] Where:

[0057] L D is the biochemical dissolved oxygen control compensation value, mg / L;

[0058] Q R is the actual membrane tank sludge return flow rate, m 3 / h;

[0059] Q Rd is the designed membrane tank sludge return flow rate, m 3 / h;

[0060] Q M is the actual membrane scrubbing air volume, m 3 / min;

[0061] Q Md is the designed membrane scrubbing air volume, m 3 / min;

[0062] DO0 is the set value of the biochemical dissolved oxygen control at time 0, mg / L;

[0063] K4 is the dynamic compensation coefficient of the membrane tank return flow, and its value-taking method is as follows:

[0064] If there is a term equal to 1 in

[0065]

[0066] K5 is the deviation coefficient of the membrane tank return flow, and its value is 2.

[0067] Furthermore, the biochemical dissolved oxygen control deviation is:

[0068] The biochemical dissolved oxygen control deviation δ D is:

[0069] δ D =DO t -DO e +L D :

[0070] DO t is the biochemical dissolved oxygen control set value at time t, mg / L;

[0071] DO e is the actual biochemical effluent dissolved oxygen value transmitted by the on-line biochemical dissolved oxygen monitor at time 0, mg / L;

[0072] L D is the biochemical dissolved oxygen control compensation value caused by the reflux fluctuation in the MBR membrane tank, mg / L.

[0073] Furthermore, the fourth control algorithm is:

[0074]

[0075] Where:

[0076] Qa t is the biochemical air volume control set value at time t, m 3 / min

[0077] Qa0 is the biochemical air volume control set value at time 0, m 3 / min;

[0078] Kp2 is the dissolved oxygen proportionality coefficient, and its value is 0 to 30;

[0079] K i2 is the dissolved oxygen integral coefficient, and its value is 0 to 1 min -1 ;

[0080] δ D is the biochemical dissolved oxygen control deviation, mg / L;

[0081] t is the integration period, and its value is 15 min.

[0082] Furthermore, the biochemical air volume control deviation δ q is:

[0083] δ q =Q at -Q ae

[0084] Where:

[0085] δ q is the biochemical air volume control deviation, m 3 / min;

[0086] Q atThe set value of the biochemical air volume control at time t, m 3 / min;

[0087] Q ae The actual biochemical air volume transmitted by the biochemical gas flowmeter at time 0, m 3 / min.

[0088] Advantages of the present invention:

[0089] 1. Through the synergistic effect of the on-line detection system, ammonia nitrogen-dissolved oxygen PLC control system, dissolved oxygen-biochemical air volume PLC control system and biochemical air volume control system, the present invention constructs a cascade control system with the effluent ammonia nitrogen control as the target parameter and the biochemical blower air volume as the control output, replacing the traditional cascade control system with the biochemical dissolved oxygen as the target parameter and the biochemical blower air volume as the control output, so as to fully consider the further degradation effect of the MBR membrane tank on pollutants and reduce the energy consumption of biochemical aeration;

[0090] 2. The present invention sets up a dissolved oxygen-biochemical air volume PLC control system. Through the compensation effect of the membrane tank reflux / dissolved oxygen feed-forward compensator, it fully considers the supplementary effect of the dissolved oxygen carried by the reflux mixed liquid on biochemical aeration and reduces the consumption of biochemical aeration.

[0091] 3. The present invention sets up an ammonia nitrogen-dissolved oxygen PLC control system. Through the compensation effect of the influent water quality and quantity / ammonia nitrogen feed-forward compensator, it considers the influence of the influent water quality and quantity on the effluent ammonia nitrogen, improves the control accuracy and reduces the energy consumption of biochemical aeration. Description of the drawings

[0092] Figure 1 is a schematic structural diagram of the MBR process precise aeration system of the present invention.

[0093] Figure 2 is a control principle diagram of the MBR process precise aeration control system of the present invention.

[0094] Reference numerals: 1 aerobic tank; 2 MBR membrane tank; 3 reflux tank; 4 biochemical blower; 5 membrane scrubbing blower; 6 generating pump; 7 reflux pump; 11 influent water flowmeter; 12 influent COD on-line monitor; 13 influent ammonia nitrogen on-line monitor; 14 effluent ammonia nitrogen on-line monitor; 15 biochemical on-line dissolved oxygen monitor; 16 sludge reflux flowmeter; 17 membrane scrubbing gas flowmeter; 18 biochemical gas flowmeter. Detailed implementation manners

[0095] To better understand the present invention, the content of the present invention will be further clarified below in conjunction with embodiments, but the content of the present invention is not limited to the following embodiments only.

[0096] Embodiment 1

[0097] Refer toFigure 1 and Figure 2 , this embodiment provides an MBR process precise aeration control system, including an on-line detection system, an ammonia nitrogen-dissolved oxygen PLC control system, a dissolved oxygen-biochemical air volume PLC control system, and a biochemical air volume control system;

[0098] The on-line monitoring system includes an influent flowmeter 11, an influent COD on-line monitor 12, and an influent ammonia nitrogen on-line monitor 13 provided at the water inlet end of the aerobic tank 1, an effluent ammonia nitrogen on-line monitor 14 provided at the water production end of the MBR membrane tank 2, a biochemical on-line dissolved oxygen monitor 15 provided in the aerobic tank 1, a sludge return flowmeter 16 provided at the return liquid inlet of the aerobic tank, a membrane scrubbing gas flowmeter 17 provided at the outlet of the membrane scrubbing fan 5, and a biochemical gas flowmeter 18 provided at the outlet of the biochemical fan 4;

[0099] The ammonia nitrogen-dissolved oxygen PLC control system includes an influent water quality and quantity / ammonia nitrogen feed-forward compensator and an ammonia nitrogen-dissolved oxygen controller; the influent flowmeter 11, the influent COD on-line monitor 12, and the influent ammonia nitrogen on-line monitor 13 are respectively connected to the inlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator, and the outlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator and the effluent ammonia nitrogen on-line monitor are respectively connected to the inlet of the ammonia nitrogen-dissolved oxygen controller;

[0100] The dissolved oxygen-biochemical air volume PLC control system includes a membrane tank return / dissolved oxygen feed-forward compensator and a dissolved oxygen-biochemical aeration air volume controller. The sludge return flowmeter 16 and the membrane scrubbing gas flowmeter 17 are respectively connected to the inlet of the membrane tank return / dissolved oxygen feed-forward compensator. The outlet of the ammonia nitrogen-dissolved oxygen controller, the biochemical on-line dissolved oxygen monitor 15, and the outlet of the membrane tank return / dissolved oxygen feed-forward compensator are respectively connected to the inlet of the dissolved oxygen-biochemical aeration air volume controller;

[0101] The biochemical air volume control system includes a biochemical air volume controller. The biochemical gas flowmeter 18 and the outlet of the dissolved oxygen-biochemical aeration air volume controller are respectively connected to the inlet of the biochemical air volume controller. The biochemical air volume controller is used to control the operation of the biochemical fan 4.

[0102] Embodiment 2

[0103] A control method for the MBR process precise aeration control system obtained in Embodiment 1 includes the following steps:

[0104] (1) The influent flowmeter 11, the influent COD on-line monitor 12, and the influent ammonia nitrogen on-line monitor 13 respectively collect the influent flow value Q of the water inlet of the aerobic tank 1 i , the influent chemical oxygen demand value COD i and the influent ammonia nitrogen value (NH3-N) i, and transmit the data to the influent water quality / quantity - ammonia nitrogen feed - forward compensator; the influent water quality / quantity - ammonia nitrogen feed - forward compensator calculates the effluent ammonia nitrogen control compensation value L through the first control algorithm N , and transmit the effluent ammonia nitrogen control compensation value L N to the ammonia nitrogen - dissolved oxygen controller.

[0105]

[0106] Where:

[0107] L N is the effluent ammonia nitrogen control compensation value, mg / L;

[0108] Q i is the actual influent water flow value transmitted by the influent water flowmeter 11, m 3 / h;

[0109] Q d is the designed influent water flow value, m 3 / h;

[0110] COD i is the actual influent chemical oxygen demand value transmitted by the influent COD on - line monitor 12, mg / L;

[0111] COD d is the designed influent chemical oxygen demand value, mg / L;

[0112] (NH3 - N) i is the actual influent ammonia nitrogen value transmitted by the influent ammonia nitrogen on - line monitor 13, mg / L;

[0113] (NH3 - N) d is the designed influent ammonia nitrogen value, mg / L;

[0114] (NH3 - N)0 is the effluent ammonia nitrogen control set value, mg / L;

[0115] K2 is the influent water quality / quantity - ammonia nitrogen dynamic compensation coefficient, and its value - taking method is as follows:

[0116] If there is a term equal to 1 in, the term is excluded from the value - taking calculation formula, and the remaining terms are used for value - taking calculation.

[0117]

[0118] K3 is the influent water quality / quantity - ammonia nitrogen deviation coefficient, and its value is 2.

[0119] Effectively associate the influent water quality / quantity with the effluent ammonia nitrogen control value in a feed - forward manner. When the deviation of the actual influent water quality / quantity from the designed influent water quality / quantity is relatively large The response of the influent water quality and quantity / ammonia nitrogen feed-forward compensator deviates, and the variable is compensated into the control of the effluent ammonia nitrogen, effectively improving the control accuracy of the system for the effluent ammonia nitrogen value, and avoiding the low-load or over-load operation of the aeration system caused by the fluctuations of the influent water quality and quantity, thus resulting in an increase in the energy consumption of the biochemical aeration system or the risk of exceeding the effluent ammonia nitrogen index. When the deviation of the actual influent water quality and quantity from the designed influent water quality and quantity is small The non-response deviation of the influent water quality and quantity / ammonia nitrogen feed-forward compensator makes full use of the adaptability and adjustment ability of the sewage biological treatment system itself to the fluctuations of the influent water quality and quantity, and avoids the frequent adjustment of the biochemical aeration control system caused by the minor fluctuations of the influent water quality and quantity.

[0120] (2) The on-line monitor 14 of the effluent ammonia nitrogen collects the effluent ammonia nitrogen value (NH3-N) e and transmits the effluent ammonia nitrogen value (NH3-N) e to the ammonia nitrogen-dissolved oxygen controller. The ammonia nitrogen-dissolved oxygen controller combines the preset effluent ammonia nitrogen control value (NH3-N)0 and the effluent ammonia nitrogen control compensation value L output by the influent water quality and quantity / ammonia nitrogen feed-forward compensator N , and calculates the ammonia nitrogen control deviation δ through addition and subtraction operations N , and transmits the ammonia nitrogen control deviation δ N to calculate the biochemical dissolved oxygen control set value DO0 through the second control algorithm.

[0121] The ammonia nitrogen control deviation δ N is:

[0122] δ N =(NH3-N)0-(NH3-N) e +L N

[0123] Where:

[0124] δ N is the ammonia nitrogen control deviation, mg / L;

[0125] (NH3-N)0 is the effluent ammonia nitrogen control set value, mg / L;

[0126] (NH3-N) e is the actual effluent ammonia nitrogen value transmitted by the on-line monitor 14 of the effluent ammonia nitrogen, mg / L;

[0127] L N is the effluent ammonia nitrogen control compensation value caused by the fluctuations of the influent water quality and quantity, mg / L.

[0128] The second control algorithm is:

[0129]

[0130] Wherein:

[0131] DO t is the set value of biochemical dissolved oxygen control at time t, mg / L;

[0132] DO0 is the set value of biochemical dissolved oxygen control at time o, mg / L;

[0133] Kp1 is the ammonia nitrogen proportionality coefficient, and its value is 0 to 5;

[0134] K i1 is the ammonia nitrogen integral coefficient, and its value is 0 to 0.1 min -1 ;

[0135] δ N is the ammonia nitrogen control deviation, mg / L;

[0136] t is the integral period, and its value is 15 min.

[0137] PI control is adopted, there is no need to eliminate the residual error, the transient process is short, and the disturbance from the dissolved oxygen measurement can be quickly overcome.

[0138] (3) The sludge return flowmeter 16 and the membrane scrubbing gas flowmeter 17 respectively collect the sludge return flow Q of the aerobic tank 1 R and the membrane scrubbing air volume Q of the MBR membrane tank 2 M , and transmit the data to the membrane tank return / dissolved oxygen feedforward compensator. The membrane tank return / dissolved oxygen feedforward compensator calculates the biochemical dissolved oxygen control compensation value L caused by the membrane tank return fluctuation through the third control algorithm D , and transmits the biochemical dissolved oxygen control compensation value L D to the dissolved oxygen-biochemical aeration air volume controller.

[0139]

[0140] Wherein:

[0141] L D is the biochemical dissolved oxygen control compensation value, mg / L;

[0142] Q R is the actual membrane tank sludge return flow, m 3 / h;

[0143] Q Rd is the designed membrane tank sludge return flow, m 3 / h;

[0144] Q M is the actual membrane scrubbing air volume, m 3 / min;

[0145] QMd For the designed membrane scrubbing air volume, m 3 / min;

[0146] DO0 is the set value of biochemical dissolved oxygen control at time 0, mg / L;

[0147] K4 is the dynamic compensation coefficient of membrane tank return flow, and the value-taking method is as follows:

[0148] If there is a term equal to 1 in it, the term is removed from the value-taking calculation formula, and the remaining terms are used for value-taking calculation.

[0149]

[0150] K5 is the deviation coefficient of membrane tank return flow, and its value is 2.

[0151] Adopt the feedforward method to effectively associate the membrane tank sludge return flow and membrane scrubbing air volume with biochemical dissolved oxygen. When the actual membrane tank sludge return flow and membrane scrubbing air volume deviate greatly from the designed membrane tank sludge return flow and membrane scrubbing air volume The membrane tank return / dissolved oxygen feedforward compensator responds to the deviation and compensates the variable into the control of biochemical dissolved oxygen, effectively improving the control accuracy of the system for biochemical dissolved oxygen, and avoiding the low-load or over-load operation of the biochemical aeration system caused by the change of MBR operation parameters, thus leading to the increase of energy consumption of the aeration system or the risk of exceeding the ammonia nitrogen index of the effluent. When the actual influent water quality and quantity deviate slightly from the designed influent water quality and quantity The influent water quality and quantity / ammonia nitrogen feedforward compensator does not respond to the deviation, making full use of the adaptability and adjustment ability of the sewage biological treatment system itself to the fluctuation of influent water quality and quantity, and avoiding the frequent adjustment of the biochemical aeration control system caused by the small fluctuation of MBR operation parameters.

[0152] (4) The on-line monitor 15 of biochemical effluent dissolved oxygen collects the dissolved oxygen value DO of the biochemical effluent e , and transmits the effluent dissolved oxygen value DO e to the dissolved oxygen-biochemical aeration air volume controller. The dissolved oxygen-biochemical aeration air volume controller combines the set value DO0 of biochemical dissolved oxygen control output by the ammonia nitrogen-dissolved oxygen controller and the biochemical dissolved oxygen control compensation value L output by the membrane tank return / dissolved oxygen feedforward compensator D , calculates the biochemical dissolved oxygen control deviation δ D through addition and subtraction operations, and calculates the set value Qa0 of biochemical air volume control from the biochemical dissolved oxygen control deviation δ D through the fourth control algorithm.

[0153] The biochemical dissolved oxygen control deviation δ D is:

[0154] δ D = DO t - DO e + L D

[0155] DO0 is the set value of biochemical dissolved oxygen control at time t, mg / L;

[0156] DO e is the actual biochemical effluent dissolved oxygen value transmitted by the on-line biochemical dissolved oxygen monitor 15 at time 0, mg / L;

[0157] L D is the compensation value of biochemical dissolved oxygen control caused by the reflux fluctuation of the MBR membrane tank, mg / L.

[0158] The fourth control algorithm is as follows:

[0159]

[0160] Where:

[0161] Qa t is the set value of biochemical air volume control at time t, m 3 / min

[0162] Qa0 is the set value of biochemical air volume control at time 0, m 3 / min;

[0163] Kp2 is the dissolved oxygen proportionality coefficient, and its value is 0 to 30;

[0164] K i2 is the dissolved oxygen integral coefficient, and its value is 0 to 1 min -1 ;

[0165] δ D is the deviation of biochemical dissolved oxygen control, mg / L;

[0166] t is the integral period, and its value is 15 min.

[0167] PI control is adopted, there is no need to eliminate the residual error, the transition process is short, and the disturbance from the measurement of biochemical air volume can be quickly overcome.

[0168] (5) The biochemical gas flowmeter 18 collects the biochemical air volume Qa e and transmits the biochemical air volume Qa e to the biochemical air volume controller. The biochemical air volume controller combines the set value Qa of the biochemical air volume output by the dissolved oxygen-biochemical air volume controller t , calculates the deviation δ of the biochemical air volume control through addition and subtraction operations q , and adjusts the output air volume of the biochemical blower 6 according to the deviation δ of the biochemical air volume control q .

[0169] δ q = Q at - Q ae

[0170] Wherein:

[0171] δ q is the deviation of biochemical air volume control, m 3 / min;

[0172] Q at is the set value of biochemical air volume control at time t, m 3 / min;

[0173] Q ae is the actual biochemical air volume transmitted by the biochemical gas flowmeter at time 0, m 3 / min.

[0174] The control values of the operating process parameters of this embodiment are shown in Table 1 below.

[0175] Table 1

[0176]

[0177]

[0178] It can be seen from the operation process control in Table 1 that when the influent water quality and quantity are both lower than the designed influent water quality, different from the traditional A2 / O precise control system which only shows a decrease in biochemical air volume, the precise aeration control system of the MBR process not only shows a decrease in biochemical air volume of 9.1 m 3 / h, but also shows a decrease in membrane scrubbing air volume of 41.7 m 3 / h, saving more than 18.9% of energy consumption compared with the existing A2 / O + MBR system.

[0179] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A precise aeration control method for MBR process, characterized in that It includes an on-line detection system, an ammonia nitrogen-dissolved oxygen PLC control system, a dissolved oxygen-biochemical air volume PLC control system and a biochemical air volume control system; The on-line monitoring system includes an influent flowmeter, an on-line influent COD monitor, an on-line influent ammonia nitrogen monitor set at the influent end of the aerobic tank, a biochemical on-line dissolved oxygen monitor set inside the aerobic tank, an on-line effluent ammonia nitrogen monitor set at the effluent end of the MBR membrane tank, a sludge return flowmeter set at the influent of the aerobic tank return liquid, a membrane scrubbing gas flowmeter set at the outlet of the membrane scrubbing fan, and a biochemical gas flowmeter set at the outlet of the biochemical fan; The ammonia nitrogen-dissolved oxygen PLC control system includes an influent water quality and quantity / ammonia nitrogen feed-forward compensator and an ammonia nitrogen-dissolved oxygen controller; the influent flowmeter, the on-line influent COD monitor and the on-line influent ammonia nitrogen monitor are respectively connected to the inlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator, and the outlet of the influent water quality and quantity / ammonia nitrogen feed-forward compensator and the on-line effluent ammonia nitrogen monitor are respectively connected to the inlet of the ammonia nitrogen-dissolved oxygen controller; The dissolved oxygen-biochemical air volume PLC control system includes a membrane tank return / dissolved oxygen feed-forward compensator and a dissolved oxygen-biochemical aeration air volume controller. The on-line effluent ammonia nitrogen monitor and the biochemical on-line dissolved oxygen monitor are respectively connected to the inlet of the membrane tank return / dissolved oxygen feed-forward compensator. The outlet of the ammonia nitrogen-dissolved oxygen controller, the biochemical on-line dissolved oxygen monitor and the outlet of the membrane tank return / dissolved oxygen feed-forward compensator are respectively connected to the inlet of the dissolved oxygen-biochemical aeration air volume controller; The biochemical air volume control system includes a biochemical air volume controller. The biochemical gas flowmeter and the outlet of the dissolved oxygen-biochemical aeration air volume controller are respectively connected to the inlet of the biochemical air volume controller. The biochemical air volume controller is used to control the operation of the biochemical fan; Specifically, it includes the following steps: (1) The influent flowmeter, the on-line influent COD monitor and the on-line influent ammonia nitrogen monitor respectively collect the influent flow value, the influent chemical oxygen demand value and the influent ammonia nitrogen value of the aerobic tank inlet, and transmit the data to the influent water quality and quantity / ammonia nitrogen feed-forward compensator; the influent water quality and quantity / ammonia nitrogen feed-forward compensator calculates the effluent ammonia nitrogen control compensation value through the first control algorithm, and transmits the effluent ammonia nitrogen control compensation value to the ammonia nitrogen-dissolved oxygen controller; (2) The on-line effluent ammonia nitrogen monitor collects the ammonia nitrogen value of the MBR membrane tank effluent and transmits the data to the ammonia nitrogen-dissolved oxygen controller. The ammonia nitrogen-dissolved oxygen controller combines the preset effluent ammonia nitrogen control value and the effluent ammonia nitrogen control compensation value output by the influent water quality and quantity / ammonia nitrogen feed-forward compensator, calculates the ammonia nitrogen control deviation through addition and subtraction operations, and calculates the biochemical dissolved oxygen control set value through the second control algorithm for the ammonia nitrogen control deviation; (3) The sludge return flowmeter and the membrane scrubbing gas flowmeter respectively collect the sludge return flow of the aerobic tank and the membrane scrubbing air volume of the membrane tank, and transmit the data to the membrane tank return / dissolved oxygen feed-forward compensator. The membrane tank return / dissolved oxygen feed-forward compensator calculates the biochemical dissolved oxygen control compensation value caused by the membrane tank return fluctuation through the third control algorithm, and transmits the biochemical dissolved oxygen control compensation value to the dissolved oxygen-biochemical aeration air volume controller; (4) The on-line biochemical dissolved oxygen monitor collects the dissolved oxygen value of the biochemical effluent and transmits the effluent dissolved oxygen value to the dissolved oxygen-biochemical aeration air volume controller. The dissolved oxygen-biochemical aeration air volume controller combines the biochemical dissolved oxygen control set value output by the ammonia nitrogen-dissolved oxygen controller and the biochemical dissolved oxygen control compensation value output by the membrane tank reflux / dissolved oxygen feed-forward compensator, calculates the biochemical dissolved oxygen control deviation through addition and subtraction operations, and calculates the biochemical air volume control set value through the fourth control algorithm for the biochemical dissolved oxygen control deviation; (5) The biochemical gas flowmeter collects the biochemical air volume and transmits the biochemical air volume to the biochemical air volume controller. The biochemical air volume controller combines the biochemical air volume control set value output by the dissolved oxygen-biochemical air volume controller, calculates the biochemical air volume control deviation through addition and subtraction operations, and adjusts the output air volume of the biochemical blower according to the biochemical air volume control deviation.

2. A precise aeration control method for an MBR process according to claim 1, wherein the first control algorithm is: Where: L N is the compensation value for controlling ammonia nitrogen in the effluent, mg / L; Q i The actual influent flow rate value transmitted by the influent flowmeter, m 3 / h; Q d is the designed influent flow rate value, m 3 / h; COD i It is the actual influent chemical oxygen demand value transmitted by the influent COD on-line monitor, mg / L; COD d is the designed influent chemical oxygen demand value, mg / L; (NH3-N) i It is the actual influent ammonia nitrogen value transmitted by the on-line monitor for influent ammonia nitrogen, mg / L; (NH3-N) d Design influent ammonia nitrogen value, mg / L; (NH3-N)0 is the effluent ammonia nitrogen control set value, mg / L; K2 is the influent water quality and quantity / ammonia nitrogen dynamic compensation coefficient, and the value-taking method is as follows: K3 is the influent water quality and quantity / ammonia nitrogen deviation coefficient, and its value is 2.

3. The precise aeration control method for an MBR process according to claim 1, wherein The ammonia nitrogen control deviation is: δ N =(NH3-N)0 - (NH3-N) e +L N Where: δ N is the ammonia nitrogen control deviation, mg / L; (NH3-N)0 is the effluent ammonia nitrogen control set value, mg / L; (NH3-N) e It is the actual ammonia nitrogen value of the effluent transmitted by the on-line ammonia nitrogen monitor for effluent, mg / L; L N is the control compensation value of ammonia nitrogen in the effluent, mg / L.

4. A precise aeration control method for the MBR process according to claim 2 or 3, characterized in that, The effluent ammonia nitrogen control set value is: (NH3-N)0 = K1(NH3-N)s Where: (NH3-N)0 is the effluent ammonia nitrogen control set value, mg / L; (NH3-N)s is the effluent ammonia nitrogen limit value set by the industry emission standard, mg / L; K1 is the safety factor, and K1 ∈ (0, 1).

5. A precise aeration control method for the MBR process according to claim 1, characterized in that, The second control algorithm is: Where: DO t is the set value of biochemical dissolved oxygen control at time t, mg / L; DO0 is the biochemical dissolved oxygen control set value at time 0, mg / L; Kp1 is the ammonia nitrogen proportionality coefficient, and its value is 0 to 5; K i1 is the ammonia nitrogen integration coefficient, and its value is 0 to 0.1 min -1 ; δ N is the ammonia nitrogen control deviation, mg / L; t is the integration period, and its value is 15 min.

6. The precise aeration control method for the MBR process according to claim 1, characterized in that, The third control algorithm is: Where: L D Biochemical dissolved oxygen control compensation value, mg / L; Q R is the actual sludge reflux flow rate of the membrane tank, m 3 / h; Q Rd For the designed return sludge flow rate of the membrane tank, m 3 / h; Q M is the actual membrane scrubbing air volume, m 3 / min; Q Md For the designed membrane scrubbing air volume, m 3 / min; DO0 is the biochemical dissolved oxygen control set value at time 0, mg / L; K4 is the membrane tank reflux dynamic compensation coefficient, and the value-taking method is as follows: If there is an item equal to 1 in it, this item is excluded from the value calculation formula, and the remaining items are used for value calculation; K5 is the membrane tank reflux deviation coefficient, and its value is 2.

7. A precise aeration control method for the MBR process according to claim 1, characterized in that The biochemical dissolved oxygen control deviation is: The biochemical dissolved oxygen control deviation δ D is as follows: δ D = DO t - DO e + L D ; DO t Biochemical dissolved oxygen control setpoint at time t, mg / L; DO e The actual dissolved oxygen value of the biochemical effluent transmitted by the on-line biochemical dissolved oxygen monitor at time 0, mg / L; L D It is the biochemical dissolved oxygen control compensation value caused by the reflux fluctuation of the MBR membrane tank, mg / L.

8. A precise aeration control method for MBR process according to claim 1, characterized in that, The fourth control algorithm is: Where: Qa t Setpoint for biochemical air volume control at time t, m 3 / min Qa0 is the set value of biochemical air volume control at time 0, m 3 / min; Kp2 is the dissolved oxygen proportionality coefficient, and its value is 0 to 30; K i2 is the dissolved oxygen integral coefficient, and its value is 0 to 1 min -1 ; δ D is the biochemical dissolved oxygen control deviation, mg / L; t is the integration period, and its value is 15 min.

9. A precise aeration control method for the MBR process according to claim 1, characterized in that, Biochemical air volume control deviation δ q is as follows: δ q = Q at -Q ae Where: δ q is the deviation of biochemical air volume control, m 3 / min; Q at is the set value of biochemical air volume control at time t, m 3 / min; Q ae The actual biochemical air volume transmitted by the biochemical gas flowmeter at time 0, m 3 / min.

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