JP2011183353A - Wastewater treatment apparatus and oxygen feed rate control method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wastewater treatment apparatus which attains reduction in the electric power consumption thereof necessary for oxygen feed when an organic matter load of a bioreactor is increased, and to procide an oxygen feed rate control method therefore. <P>SOLUTION: The wastewater treatment apparatus includes an air diffuser pipe 13 introducing gas containing oxygen into the bioreactor 11 to dissolve oxygen into wastewater, an air blowing means 20 blowing gas taken in from the exterior into the air diffuser pipe 13, a control means 17 controlling air volume sent by the air blowing means 20, an oxygen-enriched gas generation device 31 increasing the oxygen concentration in the gas, and an oxygen feed rate control means 1 controlling the oxygen amount in the gas. The oxygen feed rate control means 1 controls the operation of the air blowing means 20 and oxygen-enriched gas generation device 31 to feed oxygen with further less power, based on the relationship between the total used electric energy of the air blowing means 20 and oxygen-enriched gas generation device 31 and the oxygen amount corresponding to the air amount to be blown. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a wastewater treatment apparatus and a method for controlling the amount of oxygen supplied to a biological reaction tank that treats wastewater containing organic pollutants with aerobic microorganisms with relatively low power.

  Waste water containing organic pollutants is introduced into a biological reaction tank and biologically treated with aerobic microorganisms. In order to promote the treatment with aerobic microorganisms, it is necessary to supply oxygen by blowing a gas such as air into the biological reaction tank with a blower.

  In sewage treatment plants that perform biological treatment on a large scale, the power cost of the blower accounts for a large proportion of the facility maintenance cost, and it is desired to reduce the power consumption of the blower from the viewpoint of energy saving. It is known that the power consumed by the blower is proportional to the cube of the air volume blown by the blower. When the amount of air to be blown is increased by increasing the amount of organic matter loaded into the biological reaction tank, the blower consumption The amount of power will increase dramatically.

  Waste water containing organic pollutants is introduced into the biological reaction tank through the introduction pipe. Air is introduced into the biological reaction tank through an air diffuser, and oxygen in the air is dissolved in waste water in the biological reaction tank. As one method for controlling biological treatment in such a biological reaction tank, a control method is known in which dissolved oxygen in wastewater in the biological reaction tank is measured and made constant.

  The dissolved oxygen concentration measured by the dissolved oxygen concentration meter provided in the wastewater is input to the control means, and the control means inputs the dissolved oxygen concentration and the dissolved oxygen preset in the control means by the set value input means. Compare density settings. When the input dissolved oxygen concentration is lower than the set value, a control command is output to the blowing means to increase the blowing amount, and when the dissolved oxygen concentration is higher than the set value, the blowing amount is reduced to the blowing means. Therefore, this is a control method for outputting a control command. For example, there is one described in [Patent Document 1].

  Further, as described in [Patent Document 2], the difference between the measured value of the BOD amount and the target treated water BOD value is calculated as an index value of dirt of sewage, and the aeration air volume depending on the product of the index value and the flow rate There is one that calculates a target value of the fan and controls the blower amount of the blower according to the target value.

  In the conventional techniques described in [Patent Document 1] and [Patent Document 2], when the amount of organic matter in the wastewater introduced into the biological reaction tank increases, aerobic microorganisms consume dissolved oxygen to remove the organic matter. Since the concentration of dissolved oxygen in the wastewater decreases, the amount of air to be blown by the blowing means increases, and the power consumed by the blower increases in proportion to the cube of the amount of blown air.

  On the other hand, devices such as PSA (pressure fluctuation adsorption type) oxygen generators, chilled air separators, and oxygen-enriched membranes (hereinafter referred to as oxygen-enriched gas generators) separate oxygen in the air to produce oxygen-enriched gases. If the gas having a higher oxygen concentration than air is diffused by this device, the oxygen solubility in the wastewater is increased. Therefore, if the oxygen-enriched gas generated by this device is blown, the blowing means Since the same function can be obtained even if the amount of air to be blown is reduced, it can be expected to reduce the power consumption by the blowing means.

  In [Patent Document 3], oxygen-enriched air, which is a by-product gas of a nitrogen production apparatus provided in a semiconductor production facility, is supplied to a treated water stored in an aerobic treatment tank, aerated, and treated water is obtained. It describes that a purification process is performed.

JP 2007-144277 A JP 2000-325980 A JP 2008-229436 A

  Although the conventional technology described in [Patent Document 3] uses oxygen-enriched air, a nitrogen production apparatus provided in a semiconductor production facility is indispensable, and a biological treatment in which no nitrogen production apparatus is installed However, there is a problem that oxygen-enriched air cannot be obtained at sewage treatment plants that perform large-scale operations. In addition, the power consumption of the oxygen-enriched gas generator is relatively large, and simply using it may cause an increase in the power consumption of the entire wastewater treatment device. The reduction was not considered.

  The object of the present invention is to grasp the power consumed by the blowing means and the oxygen-enriched gas generator and the amount of oxygen to be supplied to the biological reaction tank, and take an appropriate operation method according to the amount of oxygen to be supplied. An object of the present invention is to provide a wastewater treatment apparatus and an oxygen supply amount control method thereof that can reduce power consumption used for supplying oxygen when an organic substance load in a biological reaction tank increases.

  In order to achieve the above object, the present invention provides a biological reaction tank that biologically treats wastewater containing organic pollutants with an aerobic microorganism, and introduces a gas containing oxygen into the biological reaction tank. A diffuser tube for dissolving oxygen, a blowing means for blowing gas to the diffuser tube, an oxygen-enriched gas generator for increasing the oxygen concentration in the gas, and oxygen for controlling the amount of oxygen in the gas A supply amount control device, the oxygen supply amount control device is a condition for oxygen supply set with a smaller amount of electric power from the relationship between the total power consumption of the blowing means and the oxygen-enriched gas generator and the amount of blown oxygen Thus, the operation of the blowing means and the oxygen-enriched gas generator is controlled.

  In addition, in a biological reaction tank having an air diffuser for introducing oxygen-containing gas to dissolve oxygen in the wastewater, the wastewater containing organic pollutants is biologically treated with aerobic microorganisms, From the relationship between the total amount of power used and the amount of blown oxygen, the blowing means for blowing gas to the diffuser and the oxygen-enriched gas generator for increasing the oxygen concentration in the gas by the supply amount control device The operation of the blowing means and the oxygen-enriched gas generator is controlled under the conditions for the oxygen supply set in (1).

  According to the present invention, the power used for supplying oxygen to the bioreactor can be reduced by controlling the operation of the blowing means and the oxygen-enriched gas generator when the organic load of the bioreactor is increased. Can do.

1 is a configuration diagram of a wastewater treatment apparatus including an oxygen supply amount control mechanism according to an embodiment of the present invention.

  An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a configuration diagram of a wastewater treatment apparatus equipped with an oxygen supply amount control mechanism of the present embodiment.

  As shown in FIG. 1, the wastewater treatment apparatus of this embodiment includes a biological reaction tank 11, a wastewater introduction pipe 12 for introducing wastewater containing organic pollutants into the biological reaction tank 11, and the bottom of the biological reaction tank 11. A diffuser tube 13 installed in the gas generator, a dissolved oxygen concentration meter 16 for measuring the dissolved oxygen concentration in the biological reaction tank 11, a vent tube 23 connected to the diffuser tube 13, and an oxygen amount detecting means 24 installed in the vent tube 23 And the blower 21, the inverter 22 for driving the blower 21, the control valve 32 provided in the oxygen vent pipe 33 branched from the vent pipe 23 between the oxygen amount detection means 24 and the diffuser pipe 13, upstream from the control valve 32. The oxygen amount detecting means 34 and the oxygen-enriched gas generator 31 connected to the oxygen vent pipe 33, the blowing amount control means 17 connected to the dissolved oxygen concentration meter 16, and the oxygen supply amount connected to the blowing amount control means 17. Control equipment Composed of one.

  The blower 21 and the inverter 22 constitute a blowing means 20, the blowing means 20 is provided with a power consumption detecting means 25 of the blowing means, and the oxygen-enriched gas generator 31 is consumed with the oxygen-enriched gas generator. A power detection means 35 is provided. The power consumption detection means 25 and 35, the air blowing means 20, the oxygen amount detection means 24 and 34, the control valve 32, and the oxygen-enriched gas generator 31 are connected to the oxygen supply amount control means 1 through signal lines.

  Waste water containing organic pollutants is introduced into the biological reaction tank 11 through the waste water introduction pipe 12. In the biological reaction tank 11, the gas 15 containing oxygen is introduced through the air diffuser 13, and the oxygen in the gas 15 is dissolved in the waste water 14 in the biological reaction tank.

  The necessary oxygen amount of the oxygen dissolved in the gas 15 is determined by the blowing amount control means 17 and is controlled by the blowing amount control means 17 and the oxygen supply amount control means 1 so as to be a necessary oxygen amount. The air flow control means 17 performs an operation method in which the dissolved oxygen concentration in the wastewater becomes a set value by the dissolved oxygen concentration measured and fed back by the oxygen amount detection means 24 installed in the biological reaction tank 11.

  That is, the blast amount control means 17 receives the dissolved oxygen concentration measured by the dissolved oxygen concentration meter 16 from the dissolved oxygen concentration meter 16, and the blast amount control means 17 by the received dissolved oxygen concentration and the set value input means (not shown). When the received dissolved oxygen concentration is lower than the set value, a control command is output to the oxygen supply amount control means 1 to increase the oxygen supply amount and received. When the dissolved oxygen concentration is higher than the set value, a control command is output to the oxygen supply amount control means 1 to reduce the oxygen supply amount.

  The oxygen supply amount control means 1 determines the operating states of the blower means 20 constituted by, for example, the blower 21 and the inverter 22 and the oxygen-enriched gas generator 31 based on the control command transmitted from the blower quantity control means 17. Control.

  In this control, first, when both the blowing means 20 and the oxygen-enriched gas generator 31 are used to blow air, and when the oxygen-enriched gas generator 31 is stopped and the blower means 20 is used to blow air, For each of the above, the air supply amount when the oxygen supply amount is matched with the oxygen supply amount preset by the air supply amount control means 17 is calculated.

  The former oxygen supply amount is represented by the blower air flow rate × oxygen concentration in the air + oxygen-enriched gas generator blower air amount × oxygen-enriched gas oxygen concentration, and the latter oxygen supply amount is the blower air flow rate × air. It is represented by the oxygen concentration in it.

  Next, the power consumption per unit oxygen amount when both the blower 20 and the oxygen-enriched gas generator 31 are used is calculated by Equation 1, the oxygen-enriched gas generator 31 is stopped, and the blower 20 The amount of power consumption per unit oxygen amount when the air is blown using is calculated by Equation 2. Comparing the power consumption amounts of the two, when it is determined that the former has less power consumption per unit oxygen amount, the control valve 32 is opened and the oxygen-enriched gas generator 31 is operated. To control.

  The gas supplied from both the blowing means 20 and the oxygen-enriched gas generator 31 controlled by the oxygen supply amount control means 1 is introduced into the vent pipe 23 and diffused into the biological reaction tank 11 from the aeration pipe 13. .

  When it is determined that the latter has less power consumption per unit oxygen amount, the control valve 32 is closed and the oxygen-enriched gas generator 31 is controlled to stop. In this case, the gas supplied from the blowing means 20 controlled by the oxygen supply amount control means 1 is introduced into the vent pipe 23 and is diffused into the biological reaction tank 11 from the aeration pipe 13.

  Here, when the various quantities necessary for the calculation of Equation 1 or Equation 2 are not known, they can be measured by the following measurement method.

  The amount of oxygen supplied by the blower 20 is the blower blower amount × the oxygen concentration in the air, and this is measured by the oxygen amount detector 24.

  The oxygen amount detection means 24 is not particularly limited, but is provided in an oxygen vent pipe 33 for ventilating the oxygen-enriched gas generated by the oxygen-enriched gas generator 31, and includes an oxygen concentration meter, a pressure gauge, a flow meter, and a temperature. It is sufficient that the standard state volume of oxygen can be grasped by a combination of meters and the like. Further, the oxygen concentration (about 21%) in the atmosphere may be known and the concentration detection may be omitted.

  The amount of oxygen supplied by the oxygen-enriched gas generating device 31 is the oxygen-enriched gas generating device blowing amount × oxygen-enriched gas oxygen concentration, and is measured by the oxygen amount detecting means 34.

  The oxygen amount detection means 34 is not particularly limited, but is provided in the vent pipe 23 for ventilating the air blown by the blower means 20. It is sufficient if the standard state volume can be grasped. Further, if the oxygen standard state in the oxygen-enriched gas generated by the oxygen-enriched gas generator 31 is known by the oxygen-enriched gas generator, this may be omitted.

  The power consumed by the blower 20 is measured by the power consumption detector 25 of the blower. When the power used by the blower 20 is indicated by the blower 20, this value may be used and the blower power consumption detector 25 may be omitted.

  The power consumed by the oxygen-enriched gas generator 31 is measured by the power consumption detector 35 of the oxygen-enriched gas generator. When the power used by the oxygen-enriched gas generator 31 is indicated by the oxygen-enriched gas generator 31, this value may be used and the oxygen-enriched gas generator power consumption detection means 35 may be omitted.

DESCRIPTION OF SYMBOLS 1 Oxygen supply control means 11 Biological reaction tank 12 Waste water introduction pipe 13 Aeration pipe 16 Dissolved oxygen concentration meter 17 Blowing volume control means 20 Blower means 21 Blower 22 Inverter 23 Ventilation pipes 24, 34 Oxygen amount detection means 25, 35 Power consumption detection Means 31 Oxygen-enriched gas generator 32 Control valve 33 Oxygen vent pipe

Claims (4)

  A biological reaction tank that biologically treats wastewater containing organic pollutants with aerobic microorganisms, and a diffuser tube for introducing oxygen-containing gas into the biological reaction tank to dissolve oxygen in the wastewater, Blower means for blowing gas to the air diffuser, an oxygen-enriched gas generator for increasing the oxygen concentration in the gas, and an oxygen supply amount controller for controlling the oxygen amount of the gas The oxygen supply amount control device has the condition that the oxygen supply is set with a smaller amount of power, based on the relationship between the total power consumption and the amount of blown oxygen in the blowing unit and the oxygen-enriched gas generator, and the blowing unit and A wastewater treatment apparatus characterized by controlling operation of an oxygen-enriched gas generator.   The measured value of the dissolved oxygen concentration meter provided in the biological reaction tank is fed back, and when the fed back dissolved oxygen concentration is lower than the preset value of the dissolved oxygen concentration, the blowing means and oxygen-enriched gas generation The oxygen supply amount is set to a preset oxygen supply amount for each of the case where the air is blown using both of the devices and the case where the oxygen-enriched gas generator is stopped and the air is blown using the blowing means. Calculate the amount of blast when combined, calculate the amount of power consumption per unit oxygen amount in each case, compare the amount of power consumption of both, and use both the blowing means and oxygen-enriched gas generator The wastewater treatment apparatus according to claim 1, wherein when it is determined that the amount of power consumption per unit oxygen amount is smaller in the case of blowing air, the oxygen-enriched gas generator is controlled to operate.   A biological reaction tank equipped with an air diffuser for introducing oxygen-containing gas to dissolve oxygen in the wastewater, biologically treating the wastewater containing organic pollutants with aerobic microorganisms, and supplying the oxygen From the relationship between the total amount of power used and the amount of blown oxygen from the blowing means for blowing gas to the air diffuser and the oxygen-enriched gas generator for increasing the oxygen concentration in the gas by the quantity control device, less power An oxygen supply amount control method for a wastewater treatment apparatus, characterized in that the operation of the blowing means and the oxygen-enriched gas generator is controlled under the condition of oxygen supply set by the amount.   The measured value of the dissolved oxygen concentration meter provided in the biological reaction tank is fed back, and when the fed back dissolved oxygen concentration is lower than the preset value of the dissolved oxygen concentration, the blowing means and oxygen-enriched gas generation The oxygen supply amount is set to a preset oxygen supply amount for each of the case where the air is blown using both of the devices and the case where the oxygen-enriched gas generator is stopped and the air is blown using the blowing means. Calculate the amount of blast when combined, calculate the amount of power consumption per unit oxygen amount in each case, compare the amount of power consumption of both, and use both the blowing means and oxygen-enriched gas generator The oxygen of the wastewater treatment apparatus according to claim 3, wherein the oxygen-enriched gas generator is controlled to operate when it is determined that the amount of power consumption per unit oxygen amount is smaller in the case of blowing air. Supply Control method.

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