JP2010115621A - Water supply system and wastewater treatment equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an activated sludge treatment technology which can efficiently remove nitrogen and phosphorus in wastewater using conventional wastewater treatment equipment. <P>SOLUTION: In a water supply system, three tanks of the wastewater treatment equipment are operated as a first treatment tank 30, a second treatment tank 10, and a separation tank 20 to perform activated sludge treatment. The water supply system has a pump 40, supply lines L31, L11, L21, L50 capable of transferring from a pump discharge port to the first treatment tank, the second treatment tank, the separation tank, and the outside, feed control valves V31, V11, V21, V50 for controlling the transfer of the supply lines, take-in lines L32, L12, L22, L23, L1 capable of transferring from the first treatment tank, the second treatment tank, the separation tank, and a wastewater source to a pump intake port and capable of individually transferring wastewater and activated sludge from the separation tank, take-in control valves V32, V12, V22, V23, V1 for controlling the transfer of the take-in lines, and a control portion for controlling the operation of the feed control valves and the take-in control valves so that the wastewater supplied from the wastewater source is sequentially transferred by driving the pump to the first treatment tank, the second treatment tank, and the separation tank together with the activated sludge before being discharged to the outside. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a water distribution system for operating wastewater treatment equipment to perform activated sludge treatment of wastewater and wastewater treatment equipment using the same, and in particular, using conventional wastewater treatment equipment, nitrogen and phosphorus are removed from wastewater. The present invention relates to a water distribution system having a simple configuration capable of performing activated sludge treatment that can be efficiently removed, and a wastewater treatment facility using the water distribution system.

  Many of the existing wastewater treatment facilities are designed based on the standard activated sludge method that rapidly spread during the post-war high growth period. The standard activated sludge method is a method devised mainly for removing organic substances in wastewater, and therefore does not have much removal capability for nitrogen and phosphorus. It is known that the main cause of eutrophication in closed water areas, which has become a major problem in recent years, is nitrogen and phosphorus discharged from wastewater treatment facilities. Action is required to replace it with a removable advanced treatment facility.

The countermeasure is to either install a new advanced treatment facility or to remodel an old-style facility to have a nitrogen and phosphorus removal capability. For example, according to the treatment described in Patent Document 1 below, Phosphorus can be removed efficiently.
JP 2008-23498 A

  However, since wastewater treatment facilities are generally provided in urban areas near the wastewater generation source, it is difficult to secure sufficient land when installing new facilities in another location. In addition, when rebuilding old equipment to new equipment at the same place, it is necessary to temporarily interrupt the acceptance of the current wastewater, but a large amount of wastewater that is always generated cannot be discharged untreated. In practice, it is difficult to implement. On the other hand, when retrofitting an old-fashioned facility, there is a limit to remodeling it to have sufficient processing capacity if an attempt is made to incorporate the design of an advanced processing facility under the constraints of the existing facility. In addition, since a large amount of money is required for the construction and remodeling of equipment, small and medium-sized enterprises and local governments with insufficient financial power may have to give up the introduction of advanced treatment equipment.

  The present invention is a water distribution system with a simple structure that makes it possible to implement waste water treatment capable of efficiently removing nitrogen and phosphorus by activated sludge by utilizing conventional waste water treatment equipment, and using the same It is an object of the present invention to provide a wastewater treatment facility capable of suitably removing nitrogen and phosphorus from wastewater by proceeding with activated sludge treatment.

  In addition, the present invention provides a water distribution system that can implement efficient activated sludge treatment by controlling water distribution using simple components that are not economically burdened, and by installing and operating the water distribution system. An object of the present invention is to provide a wastewater treatment facility capable of suitably removing nitrogen and phosphorus from wastewater.

  In order to solve the above-mentioned problems, the present inventors have conducted extensive research, and by devising the configuration of the water distribution line installed in the wastewater treatment facility having three tanks, the wastewater can be efficiently discharged using a pump. The present inventors have found that it is possible to construct a batch activated sludge treatment capable of suitably removing nitrogen and phosphorus by distributing water to each tank, and the present invention has been completed.

  According to one aspect of the present invention, the water distribution system operates as an activated sludge treatment system in which three tanks of a wastewater treatment facility are operated as a first treatment tank, a second treatment tank, and a separation tank that separates activated sludge from wastewater. A pump system for transferring waste water and / or activated sludge; and a first treatment tank, a second treatment tank, and a separation tank from an outlet of the pump apparatus. A supply line capable of being transferred to the outside, and a supply control valve for controlling the transfer to the first treatment tank, the second treatment tank, the separation tank and the outside by the supply line; The first treatment tank, the second treatment tank, the separation tank, and the wastewater source can be transferred to the intake of the pump device, and the wastewater and activated sludge can be individually transferred from the separation tank. A line; and by the intake line An intake control valve for controlling the transfer from each of the treatment tank, the second treatment tank, the separation tank, and the wastewater source; the wastewater supplied from the wastewater source is discharged to the outside by driving the pump device; A control unit that controls the operation of the supply control valve and the intake control valve so that the first control tank, the second processing tank, and the separation tank are transferred together with the activated sludge in this order. This is the gist.

  In addition, according to the above aspect, the wastewater treatment facility according to the present invention has at least three tanks, the water distribution system is provided, and the three tanks are a first treatment tank for activated sludge treatment, The gist is to operate as a second treatment tank and a separation tank for separating activated sludge from wastewater.

  According to another aspect of the present invention, the water distribution system operates as three activated water sludge treatment tanks as a treatment tank and a first separation tank and a second separation tank for separating activated sludge from the waste water. A water distribution system for carrying out treatment, one pump device for transferring waste water and / or activated sludge; and the treatment tank, the first separation tank, and the second separation from an outlet of the pump device A supply line capable of transferring to each of the tank and the outside; a supply control valve for controlling the transfer to the processing tank, the first separation tank, the second separation tank, and the outside by the supply line; An intake line capable of being transferred from each of the treatment tank, the first separation tank, the second separation tank, and a wastewater source to an intake port of the pump device; the treatment tank by the intake line; 1 separation tank, the second separation tank and wastewater source An intake control valve for controlling the transfer from each of them; by driving the pump device, waste water supplied alternately from the waste water source to one of the first separation tank and the second separation tank is discharged to the outside. A control unit for controlling the operation of the supply control valve and the intake control valve so as to be alternately transferred to one of the first separation tank and the second separation tank through the treatment tank together with activated sludge. It is summarized as having.

  Further, according to the above aspect, the wastewater treatment facility according to the present invention has at least three tanks, the water distribution system is provided, and the three tanks are treatment tanks for activated sludge treatment, and The gist is to operate as a first separation tank and a second separation tank for separating activated sludge from wastewater.

  According to the present invention, a batch type activated sludge treatment capable of suitably removing nitrogen and phosphorus can be carried out using a treatment facility including at least three treatment tanks, and wastewater can be efficiently discharged without special equipment modification. Processing can be performed. Moreover, the improvement in the activated sludge treatment apparatus for performing wastewater treatment is a simple one constituted by a water supply / drainage line including a pump, and does not require complicated operation and process management, and can be easily installed and improved in a short time. Can proceed. Therefore, while maintaining the operating state of the conventional standard activated sludge method, upgrade to an advanced treatment facility that can remove nitrogen and phosphorus while minimizing the number of additional parts and purchasing costs while using existing facilities. can do. In addition, when the quality of the wastewater changes, it can be flexibly dealt with by changing the time spent in each process such as denitrification, nitrification, and sedimentation, so that no large-scale equipment modification is required.

  In general, the standard activated sludge process is performed continuously, and the raw wastewater that has flowed into the raw water tank flows down to the aeration tank and is aerated together with the activated sludge to be oxidized and purified (decomposition of organic substances). Sufficiently purified wastewater flows down to the sedimentation tank together with the activated sludge. After the activated sludge settles, the supernatant wastewater is discharged, and the sedimented sludge is returned to the aeration tank to maintain the activated sludge concentration in the aeration tank.

  The above equipment requires at least one pump and one aeration blower as power, but the water supply from the raw water tank to the aeration tank and the water supply from the aeration tank to the settling tank are flowing down due to gravity, and sedimentation. Use power pumping to return sludge.

  In the present invention, the above-described components are utilized to improve the advanced processing type equipment capable of removing phosphorus and nitrogen simultaneously. Specific examples thereof will be described below.

  FIG. 1 shows an embodiment of a wastewater treatment facility equipped with a water distribution system according to the present invention. This treatment equipment 1 is equipped with a water distribution system in equipment having three tanks. The three tanks are a treatment tank 10 for containing waste water W and activated sludge S, and activated sludge S contained in waste water W. Is used as a separation tank 20 for settling and separating the activated sludge S, and as a pretreatment tank 30 for supplying a new wastewater Wa to a part or all of the separated activated sludge S to perform an anaerobic condition. . The water distribution system includes a pump device 40, a water distribution line, a switching valve system that switches communication / blocking of the water distribution line, and a control unit (not shown) that systematically manages and controls the switching valve system. The water distribution line is composed of a supply line for supplying waste water and / or sludge from the discharge port of the pump device 40 to each part, and an intake line for taking waste water and / or sludge from each part to the inlet of the pump device. Consists of a supply control valve for switching communication / blocking with each part of the supply line and an intake control valve for switching communication / blocking with each part of the intake line. In FIG. 1, the supply control valve is configured by a plurality of on-off valves provided for each branch line where the supply line branches to each part, and the intake control valve is provided for each branch line of the intake line. It consists of an on-off valve. Specifically, the supply line includes a line L11 to the treatment tank 10, a line L21 to the separation tank 20, a line L31 to the lower treatment tank 30, and a line L50 to the outside that is a discharge destination of the treated wastewater. On-off valves V11, V21, V31, and V50 that individually switch communication / blocking of these lines are provided as supply control valves. The intake line has a line L12 from the treatment tank 10, lines L22 and L23 from the separation tank 20, a line L32 from the lower treatment tank 30, and a line L1 for taking waste water from the waste water source. As control valves, on-off valves V12, V22, V23, V32, and V1 for individually switching communication / blocking of these lines are attached. The line L22 and the on-off valve V22 are a line for discharging the water distribution of the supernatant sedimented and separated in the separation tank 20 and a valve for opening and closing the line, while the line L23 and the on-off valve V23 are settled and separated in the separation tank 20 2 is a line for discharging activated sludge at the bottom of the separation tank 20 and a valve for opening and closing the line. Aeration devices 11 and 31 for supplying oxygen (air) to the water distribution, and stirring devices 12 and 32 for uniformly mixing waste water are attached to the bottoms of the treatment tank 10 and the lower treatment tank 30, respectively. . The on-off valves V1, V11, V12, V21, V22, V23, V31, V32, and V50 are valves that can control the opening / closing operation by electromagnetic control, hydraulic control, mechanical control, etc. By connecting to a control unit via a connecting means (not shown), the individual opening / closing operations of each on-off valve can be systematically managed and controlled in the control unit. By controlling one of the supply control valves and one of the intake control valves to open, one of the supply lines and one of the intake lines communicate with each other via the pump device, and three pumps are driven by driving the pump device. Wastewater and / or sludge is transferred from one of the tanks and the wastewater source to one of the three tanks and the outside. Further, the operation control of the pump device 40, the stirring devices 12, 32 and the aeration devices 12, 32 can be systematically managed and controlled together with the control of the on-off valve in the control unit.

  The treatment tank 10 includes an aeration apparatus 11 which is an oxygen supply means capable of switching operation for adjusting waste water and activated sludge in the tank to an aerobic condition, and a stirring apparatus 12 for mixing the waste water and activated sludge. It acts as a treatment mechanism for performing activated sludge treatment of wastewater. The activated sludge treatment performed in the treatment tank 10 includes an anaerobic process for adjusting wastewater to an anaerobic condition and an aerobic process for adjusting subsequent wastewater to an aerobic condition. In the anaerobic process, the waste water W and the activated sludge S are mixed in the treatment tank 10 by the stirring device 12, and at this time, the inside of the tank is shut off from outside air as necessary in order to obtain an anaerobic state. If the dissolved oxygen is negligible, it is not necessary to shut off the outside air. In this step, nitrate nitrogen in the wastewater W is reduced by the activity of the denitrifying bacteria and is released as nitrogen from the wastewater W (denitrification). Agitation prevents local water quality changes in the wastewater. If denitrification is completed and nitrate nitrogen disappears, the phosphorus accumulating bacteria are activated and the phosphorus accumulating bacteria become dominant in reproduction. In the next aerobic process, the stirrer 12 is stopped and air is blown into the waste water W and the activated sludge S from the aerator 11 so as to be in an aerobic state, and the ammonia nitrogen in the waste water W is oxidized by nitrifying bacteria and nitric acid. Produce. At this time, the phosphorus-accumulating bacteria propagate using the organic matter that has been taken in and also take up phosphorous phosphorus. At this stage, the phosphorus-accumulating bacteria must be contained in the sludge so that the removal of phosphate phosphorus in the wastewater can proceed satisfactorily. In the treatment tank 10, the opportunity for the phosphorus-accumulating bacteria to have an advantage in reproduction is extremely limited. For this reason, the process for enabling the propagation of phosphorus accumulating bacteria in the sludge and the enhancement of the phosphorus uptake capacity is performed in the aftertreatment tank 30 described later. In addition, if the bacteria that have incorporated phosphorus are separated and discarded from the wastewater, they will be released again into the wastewater under anaerobic conditions, so that it is necessary to dispose of sludge for phosphorus removal as the wastewater treatment is repeated. This is done in the separation tank 20.

  Part of the waste water W and activated sludge S after denitrification, nitrification and phosphorus uptake in the treatment tank 10 are discharged from the treatment tank 10 by the line L12, the on-off valve V12 and the pump device 40, and the line L21. , And is accommodated in the separation tank 20 through the on-off valve V21 (that is, the on-off valves V12, V21 are opened for a predetermined time).

  In the separation tank 20, waste water containing sludge separated from the treatment tank 10 is separated into activated sludge S and waste water W. In this embodiment, the activated sludge S is collected at the bottom of the separation tank by sedimentation separation. However, mechanical separation means for collecting sludge such as lake may be used as the separation means. The waste water W separated from the activated sludge S is discarded from the separation tank 20 through the line L50 and the on-off valve V50 using the line L22, the on-off valve V22 and the pump device 40 (that is, the on-off valves V22 and V50 are opened for a certain period of time). ). The activated sludge S remains in the separation tank 20 in the state of the concentrated sludge containing the waste water W. From the viewpoint of the efficiency of the subsequent pretreatment, the separation efficiency is increased as much as possible so that the waste water W remaining in the activated sludge S is small. It is desirable.

  A part of the concentrated sludge S in the separation tank 20 is discharged by the line L23, the on-off valve V23 and the pump device 40 and supplied to the lower treatment tank 30 through the line L31 and the on-off valve V31 (that is, the on-off valve V23, V31 is opened for a certain period of time). The remaining sludge is discharged from the separation tank 20 in order to remove phosphorus taken up by the phosphorus accumulating bacteria from the treatment system (using the bottom discharge line of the separation tank 20 or opening the on-off valves V23 and V50 for a certain period of time. Discharged from the lines L23 and L50), incinerated, etc. and discarded. However, if the activated sludge S has a sufficient phosphorus uptake capacity for the phosphorus accumulating bacteria and can further take up phosphorus, the concentrated sludge in the separation tank 20 may be supplied to the pretreatment tank 30. This determination can be made based on the measured value of the phosphoric acid concentration of the wastewater in the separation tank 20.

  In the lower treatment tank 30, new waste water Wa taken into the sludge supplied from the separation tank 20 using the line L 1, the on-off valve V 1 and the pump device 40 is supplied through the line L 31 and the on-off valve V 31 (that is, the on-off valve V1 and V31 are opened for a certain period of time), and if necessary, the inside of the tank is shut off from the outside air, so that the new waste water Wa and the activated sludge S are taken under anaerobic conditions. The pretreatment tank 30 is equipped with a stirring device 32 for mixing the waste water Wa and the activated sludge S. By stirring the waste water Wa, the activated sludge S is dispersed and local quality change is prevented. Sludge activation becomes uniform. In this state, the residual nitrate nitrogen from the waste water W contained in the activated sludge S is converted to nitrogen by the denitrifying bacteria, and the denitrification is completed and the nitrate nitrogen disappears (anaerobic state without nitrate nitrogen) When described as absolute anaerobic), the phosphorus-accumulating bacteria are activated and take in abundant organic matter in the wastewater, leading to better reproduction than other bacteria. Therefore, it grows in an aerobic state in the subsequent treatment tank 10 and the phosphorus accumulation capacity of the activated sludge S increases. The phosphorus storage capacity of the sludge discarded from the separation tank 20 to the outside of the system is replenished by the phosphorus storage capacity that is increased by this multiplication. In order for the pretreatment to function effectively, the amount of the new waste water Wa supplied to the concentrated sludge makes the absolute nitrogen anaerobic by substantially completing the denitrification of nitrate nitrogen remaining in the activated sludge S. It is important to be able to supply a sufficient amount of organic matter (ie more than the complete equivalent). Since wastewater after sludge treatment has a small organic mass, there is a possibility that filamentous bacteria will grow in the sludge depending on the handling. However, when it comes into contact with new wastewater with a high organic concentration in the sludge treatment tank 30, Bacterial growth is prevented. The pretreatment tank 30 also functions as a means for avoiding inadvertent growth of filamentous bacteria in the treatment tank 10. Specifically, the organic concentration of wastewater after sludge treatment in the treatment tank 10 is close to zero, and when new wastewater is added directly to the treatment tank 10, there is a possibility that the growth of filamentous bacteria may be accelerated depending on the mixing situation. In particular, the possibility is high when the organic concentration of wastewater before treatment is about 100 mg-COD / L or less, but when passing through the pretreatment tank 30, nitrifying bacteria activated in the pretreatment tank 30 and Since the floc-forming bacteria are introduced together with the waste water, the nitrifying bacteria and the floc-forming bacteria ingest the organic matter before the filamentous bacteria are activated in the treatment tank 10, which is effective for suppressing the propagation of the filamentous bacteria. Accordingly, the pretreatment tank 30 is a useful means even when the anaerobic bacteria are not anaerobic in the pretreatment tank and the phosphorus accumulating bacteria are not activated due to fluctuations in waste water quality, separation efficiency of the separation tank, and the like. In addition, if the present invention is applied to wastewater treatment that does not require phosphorus removal, the lower treatment tank 30 can be used as a means for ensuring the prevention of the growth of filamentous bacteria. It is not necessary to complete.

  If oxygen is supplied to the concentrated sludge S prior to the above-mentioned pretreatment, the organic matter in the residual wastewater and the stored organic matter accumulated in the sludge are oxidatively decomposed and the bacteria in the sludge are starved, so the new wastewater Wa When the organic substance is supplied, the rate at which the bacteria take up the organic substance increases, and the effectiveness of the pretreatment is improved. This oxygen supply is possible by an aeration process, and can be efficiently carried out by providing an aeration apparatus 31 for supplying a gas such as oxygen or air containing this in the lower treatment tank 30 and blowing air or the like. In addition, it can replace with the aeration apparatus 31, and can also obtain the same effect using a stirring apparatus. In this case, the combined oxygen of nitric acid is consumed (denitrified) instead of oxygen.

  The new waste water Wa and activated sludge S after the pretreatment are recirculated by the pump device 40 via the line L32 and the on-off valve V32 and supplied to the treatment tank 10 from the line L11 and the on-off valve V11 (that is, the on-off valve V32). , V11 is opened for a certain period of time). The amount of water in the treatment tank 10 returns to the full water level (indicated by a broken line F in the figure), and the residual waste water W added with the new waste water Wa is activated by the activated sludge S containing activated phosphorus-accumulating bacteria after the pretreatment. Sludge treatment is performed again. The empty pretreatment tank 30 after reflux may contain new wastewater and be used as a reservoir for raw wastewater.

  Therefore, when the supply control valve and the intake control valve are switched as described above in accordance with the operation control of the control unit, the wastewater supplied from the wastewater source by driving the pump device 40 is treated as a pretreatment through the water distribution line. After moving together with activated sludge in the order of the treatment tank 10 (second treatment tank) and the separation tank 20 from the tank (first treatment tank) 30, it is separated from the sludge and discharged to the outside. The opening and closing operation of the supply control valve and the intake control valve is repeated intermittently in units of waste water or activated sludge capacity accommodated in the sewage treatment tank 30 (transfer and supply) of waste water or sludge through the distribution line. Controlled to be done.

  As described above, the ammonia state in the wastewater is obtained by repeating the above-described sludge treatment, fractionation operation, separation operation, pretreatment and reflux operation while intermittently supplying new wastewater Wa to the pretreatment tank 30. Nitrogen and phosphate phosphorus are removed, and the wastewater to be treated whose nitrate nitrogen concentration is reduced to an acceptable low concentration is discharged from the separation tank 20 of the activated sludge treatment apparatus. The phosphorus in the wastewater is taken up by the phosphorus accumulating bacteria of the activated sludge and discarded together with a part of the activated sludge S collected in the separation tank 20. At this time, by equalizing the volume of the waste water discharged from the separation tank 20 and the volume of the new waste water Wa supplied to the activated sludge S in the lower treatment tank 30, the waste water subjected to the sludge treatment in the treatment tank 10. The volume (total amount) becomes constant.

  In general, sedimentation and separation of activated sludge requires a long time. Therefore, proceeding with sludge treatment of wastewater in the treatment tank 10 in parallel with the separation operation in the separation tank 20 is advantageous in terms of efficiency of treatment and operation, and wastewater The three tanks 10, 20, and 30 of the processing facility 1 can be utilized without waste. For this purpose, for example, as an initial treatment, a pretreatment is performed in advance in the pretreatment tank 30 with new wastewater and activated sludge, and a part of the wastewater and sludge after the sludge treatment is separated into the separation tank 20. After replenishing (the state shown in FIG. 1) the treatment tank 10 with the treated waste water Wa and activated sludge S, the separation operation and the sludge treatment can proceed in parallel. The amount of wastewater that can be treated can be increased, which is substantially equivalent to a reduction in time required for treatment. In this case, when the sludge treatment is completed while the activated sludge after separation is subjected to the pretreatment, the fractionation operation from the treatment tank 10 may be performed in parallel, (a: sludge treatment / separation, b: wastewater disposal, c: Pretreatment / waste water removal, d: reflux) is taken as one cycle, and the treatment and operation are repeated. The sign of the on-off valve opened in the operation of the water distribution system during this period is b: V22, V50 (external from the separation tank 20), bc: 1) V23, V31 (separation tank 20 to the pretreatment tank 30), 2) V1, V31 (waste water source to lower treatment tank 30), c: V12, V21 (treatment tank 10 to separation tank 20), d: V32, V11 (lower treatment tank 30 to treatment tank 10), and each waste water Opened for the time required for transfer. When the activated sludge that has reached phosphorus uptake saturation is discharged from the line L50, the sign of the on-off valve opened between bc is 1) V23, V31 (from the separation tank 20 to the pretreatment tank 30), 2) V23, V50 (from the separation tank 20 to the outside), 3) V1, V31 (from the wastewater source to the sewage treatment tank 30), or 1) and 2) may be in reverse order, and the sludge separation in the above a may be performed. When the waste water b is discarded in an insufficient state, some sludge can be discarded together.

  In the sludge treatment in the treatment tank 10, ammonia nitrogen contained in the new wastewater to be added remains as nitrate nitrogen in the wastewater after the sludge treatment. The concentration of nitrate nitrogen in the wastewater is about the same as the ammonia nitrogen concentration in the wastewater at the start of the treatment, that is, after the first sludge treatment. The waste water to be treated is discarded from the separation tank 20.

  In a state where the wastewater treatment is in a steady state, the concentration ratio between the ammonia nitrogen concentration A of the wastewater before treatment and the nitrate nitrogen concentration N of the wastewater after sludge treatment is the volume V of the wastewater (total amount) subjected to sludge treatment. Is substantially equivalent to the ratio (water volume ratio) of the volume of waste water to be added in the pretreatment, and the nitrate nitrogen concentration N of the discharged waste water is N = A × (v / V). Depends on the proportion of wastewater. Assuming that the maximum nitrate nitrogen concentration allowed for the water to be discarded is Nmax, in order to satisfy N ≦ Nmax, v / V ≦ Nmax / A, so the water volume ratio v / V is changed to the concentration ratio Nmax / A. Set roughly based on. At this time, the minimum value of the volume v of the new wastewater is an amount necessary for the pretreatment to be effective, and the maximum value is an amount at which the nitrate nitrogen concentration of the wastewater to be discarded becomes Nmax. A method in which the initial water amount ratio v / V is set smaller than the value set in accordance with the concentration ratio described above and is increased stepwise, or the amount of waste water in the initial sludge treatment is set to be less than the total amount V (for example, V− v) Then, there is a method of adding new wastewater after the pretreatment without separating and separating the wastewater after the sludge treatment. However, it is necessary to consider the amount of residual wastewater in the separated sludge, which is determined in consideration of the separation efficiency of wastewater and sludge in the separation tank 30.

  In the regularization by the above repetition, the phosphorus accumulating bacteria in the activated sludge S are activated in the pretreatment tank 30 and propagated in the aerobic process, thereby increasing the phosphorus accumulating ability of the activated sludge, but new waste water is By being repeatedly added, the amount of phosphorus in the treatment system reaches the saturation amount of bacterial uptake. Therefore, when the uptake saturation amount is reached, only a part of the activated sludge S in the separation tank 20 is subjected to the pretreatment as described above. However, until the uptake saturation amount is reached, all of the activated sludge in the separation tank is subjected to the pretreatment. be able to. Whether or not the intake saturation has been reached can be determined based on the monitoring result of the phosphate phosphorus concentration of the wastewater after the sludge treatment, and can be detected by the increase of the phosphorus concentration of the wastewater. The amount of activated sludge to be discarded depends on the amount of phosphorus added by the new wastewater, and is set in consideration of the amount of phosphorus uptake that can be increased by the pretreatment. The amount of activated sludge used in the sludge treatment is generally about 0.2 to 0.6 kg COD / (kg activated sludge / day) per kg of organic matter treated per day, but the total amount of activated sludge S. It is preferable to discard about 3-7 dry mass% (or volume%) per day.

  In the above description, it is assumed that the quality of the wastewater supplied to the wastewater treatment facility 1 is constant and does not contain nitrate nitrogen. Optimize the nitrate nitrogen concentration of the wastewater to be treated by appropriately adjusting the water ratio and anaerobic / aerobic time distribution according to the fluctuation of the concentration ratio while constantly monitoring the ammonia nitrogen concentration of the wastewater Can be controlled.

  The capacities required for the separation tank 20 and the pretreatment tank 30 described above can be regarded as the same (however, the change in the amount of additional wastewater due to fluctuations in the quality of the wastewater is actually taken into account). The above-described embodiment can be modified so that two tanks (first and second separation tanks) are used alternately. Specifically, waste water discharged from the treatment tank 10 is accommodated in a first separation tank, and new waste water is added to the sludge after the sludge is settled and the waste water is removed to perform the pretreatment. The wastewater to be treated that is separated next from the treatment tank 10 is accommodated in the second separation tank, and similarly, sedimentation and discharge of the wastewater are performed, and the pretreatment is performed in the second separation tank. The wastewater that has been subjected to the pretreatment in the first separation tank may be returned to the treatment tank after being separated into the second separation tank. Therefore, the waste water supplied alternately from the waste water source to one of the first separation tank and the second separation tank by driving the pump device passes through the treatment tank together with the activated sludge to one of the first separation tank and the second separation tank. Thereafter, the operation of the on-off valve is controlled so as to be separated from the sludge and discharged to the outside. The transfer unit of waste water and sludge is the capacity of waste water and sludge stored in each of the first and second separation tanks. In this embodiment, the agitating device 32 used in the lower treatment tank 30 of FIG. 1 and the aeration means 31 for aeration treatment of sludge are used for both the first and second separation tanks (the separation tank 20 and the lower treatment tank 30). ) To control switching operation. In order to discharge the sludge saturated with phosphorus uptake, an excess sludge discharge port at the bottom of the separation tank 20 in FIG. 1 can also be provided in the pretreatment tank 30. In this case, the sludge discharge line L23 and the open / close The valve V23 becomes unnecessary. Alternatively, the sludge discharge line L23 and the open / close valve V23 may be installed in the lower treatment tank 30 (second separation tank) as the line L33 and the open / close valve V33, and the sludge may be discharged to the outside through the line 50. . For example, (a: sludge treatment / separation 1, b: waste water disposal 1, c: pretreatment 1 / waste water removal 2, d: reflux 1, e: sludge treatment) / Separation 2, f: waste water disposal 2, g: pretreatment 2 / waste water removal 1, h: reflux 2), and treatment and operation are repeated. The sign of the on-off valve opened in the operation of the water distribution system during this period is as follows: b: V22, V50, bc: V1, V21, c: V12, V31, d: V22, V11, f: V32, V50, f Between -g: V1, 31, g: V12, V21, h: V32, V11. When the activated sludge that has reached saturation of phosphorus uptake is discharged from the line L50, the open / close valve that opens between b-c and f-g is, for example, between b-c: 1) V23, V50, 2) V1, V21, f-g: 1) V33, V50, 2) V1, V31. Alternatively, part of sludge may be discarded together with the wastewater disposal of b and f in a state where the separation in the above operations a and e is insufficient.

  When the time required for the separation operation in the separation tank 30 is extremely long compared to the time required for the sludge treatment (anaerobic treatment + aerobic treatment) in the treatment tank 10, in order to efficiently use the wastewater treatment facility, for example, Applications such as a) repeating the sludge treatment in the treatment tank 10 and b) separating the sludge in two stages and performing the initial separation in the treatment tank 10 are possible.

  In the a), since the wastewater after the aerobic treatment is insufficient in organic matter, it is necessary to replenish the organic matter by adding wastewater so that denitrification in the anaerobic treatment can proceed before the sludge treatment is repeated. Therefore, when the sludge treatment in the treatment tank 10 is repeated, the amount of wastewater in the first sludge treatment is set in consideration of the amount of wastewater added when the sludge treatment is repeated.

  In b), the activated sludge S is collected in the lower part of the treatment tank 10 and concentrated to some extent by performing a separation operation such as sedimentation on the wastewater that has been subjected to the sludge treatment in the treatment tank 10. When the separation tank 20 (or one of the first and second separation tanks) is empty, the semi-concentrated sludge in the treatment tank 10 is discharged to the separation tank 20. In this case, since the ratio of the sludge to the wastewater in the discharge is increased, the amount of sludge to be subjected to the pretreatment through the separation operation can be increased, which is advantageous in enhancing the phosphorus storage capacity. The amount of concentrated sludge discharged and collected at this time is adjusted in consideration of the separation efficiency as including the residual waste water v ′ of the separated sludge in the separation tank 20 (v + v ′), so that this approaches the new waste water amount v. The operation in the separation tank 30 is optimized. Such adjustment can be realized, for example, by installing a sludge interface meter in the separation tank 20 and reflecting the separation state in the separation tank 20 in the discharge amount in the sorting operation. Specifically, the amount of supernatant wastewater that can be discharged from the separation tank 20 and the ratio of the supernatant wastewater to the concentrated sludge are determined by detecting the interface position with a sludge interface meter when sludge is settled and separated in the separation tank 20. Is done. By calculating the difference between the amount of supernatant wastewater and the amount of new wastewater v and reducing the concentrated sludge discharged from the treatment tank 10 by a ratio corresponding to this difference, the residual wastewater amount v ′ during the separation operation is separated. It is possible to reduce the amount of the sludge and the phosphorus accumulating bacteria, and to activate them with high efficiency.

  If the supply of wastewater from the wastewater source to the wastewater treatment facility cannot be interrupted and it is necessary to always accept the wastewater, two measures can be taken. The first countermeasure is to store the waste water from the waste water source in another tank (fourth tank) or the tank if it can be used. From the above-mentioned a: sludge treatment / separation, from the line L1 Supply. As a second countermeasure, when an additional tank or the like cannot be used, a line L1 for supplying wastewater from a wastewater source is arranged so as to supply wastewater directly to the lowertreatment tank 30, and the lower treatment tank 30 is stored in water. It can also be used as a tank, and the line L31 and the open / close valves V1, V31 are omitted. In this case, since the activated sludge aeration process is omitted in the lower treatment tank 30, the activation effect of the phosphorus accumulating bacteria is reduced accordingly.

  FIG. 2 shows an embodiment in which the supply control valve and the intake control valve constituted by a plurality of on-off valves in FIG. 1 are each constituted by a single switching device Vs, Vr. This switching device uses, for example, a configuration in which a plurality of on-off valves in FIG. 1 are integrated into a valve unit having a single inlet (or outlet) and a plurality of outlets (or inlets). A structure in which the communication path is switched and shifted at a branch point of a multi-branch path having an inlet (or outlet) and a plurality of outlets (or inlets) can be used, but is not limited thereto. In such a configuration, the structure of the water distribution line is simplified, so that handling of line load and the like becomes easy.

  2 can be applied and modified in the same manner as in FIG. 1, and the line L1 is directly connected to the line L31 so that the lower treatment tank 30 is also used for water storage, or the separation tank 20 and the lower treatment. It is possible to exchange and use the tank 30 alternately.

  Volume which performs separation of activated sludge by constituting a water distribution line as mentioned above, fractionating only a part of waste water processed in processing tank 10, and performing activated sludge separation and pretreatment Is easy to improve separation efficiency. In addition, the energy required for aeration in the pretreatment can be saved, and the organic matter of the wastewater can be used in a high concentration state, so that the activation efficiency of bacteria is also high. Moreover, since sludge treatment and sludge separation of wastewater can be performed in parallel, the treatment efficiency is high, and it is possible to cope with a smaller device than a batch-type device that performs all in a single tank.

  Hereinafter, the activated sludge treatment method and apparatus for wastewater according to the present invention will be specifically described with reference to examples.

  The following operations were performed using a wastewater treatment facility having three tanks.

  1 is installed in a wastewater treatment facility, a treatment tank 10 having a capacity of 5 L, a separation tank 30 having a capacity of 830 ml, and a pretreatment tank 40 having a capacity of 830 ml. Configured. Using this wastewater treatment facility, raw wastewater having an ammonia concentration of 650 mg-N / L, nitric acid / nitrous acid concentration of 0 mg-N / L, and phosphoric acid concentration of 25 mg-P / L was treated as follows.

  First, as an initial treatment, activated sludge was charged into the treatment tank 10, the pump device 40 was operated, the on-off valves V1 and V11 were opened, filled with raw waste water (5L) and closed. Nitrogen gas was used to block the outside air to make the anaerobic state, the stirrer 12 was operated for 52 minutes to perform anaerobic treatment, and denitrification by denitrifying bacteria was advanced. Thereafter, the aeration apparatus 11 was operated to make an aerobic condition, and the nitrification by the lower nitrifying bacteria was advanced by performing the aerobic treatment for 197 minutes, and the sludge treatment was completed. In parallel with the sludge treatment in the treatment tank 10, activated sludge is introduced into the lower treatment tank 30 and air is blown in the aeration apparatus 31 for 59 minutes, and then an anaerobic state is established by shutting off from the outside air using nitrogen gas. The on-off valves V1 and V31 were opened and filled with raw waste water (830 ml), closed, and stirred for 21 minutes with the stirring device 32 to advance denitrification to make it absolutely anaerobic. Open / close valves V12, V21 are opened and 830 ml of waste water containing activated sludge in the treatment tank 10 is discharged to the separation tank 30 and then closed, and the open / close valves V32, V11 are opened to remove the activated sludge in the lower treatment tank 30. The contained waste water was supplied to the treatment tank 10.

  Next, the sludge process (52 minutes + 197 minutes) which consists of the anaerobic process and aerobic process same as the above-mentioned was performed for regularization. During the sludge treatment, the waste water in the separation tank 20 is allowed to settle and separate to concentrate the sludge to the bottom, and then the on-off valves V22 and V50 are opened to discard 415 ml of the supernatant waste water from the separation tank 20. Closed, the on-off valves V23 and V31 were opened, and the concentrated sludge (including 415 ml of wastewater) remaining at the bottom of the separation tank 20 was transferred to the pretreatment tank 30. After air was blown into the concentrated sludge in the sewage treatment tank 30 for 59 minutes with an aeration device 31, the air was shut off from the outside air using nitrogen gas to make it anaerobic, and the on-off valves V 1 and V 31 were opened and 415 ml of raw waste water was supplied. The mixture was closed and stirred for 21 minutes with the stirring device 44 to advance denitrification to make it absolutely anaerobic. Thereafter, separation of the wastewater after the sludge treatment (830 ml) and return of the wastewater after the pretreatment to the treatment tank 10 (830 ml) were performed in the same manner as described above. This steadying operation was repeated for a total of 70 times.

  In the above repetition, the concentration of nitric acid and nitrous acid in the wastewater after the sludge treatment in the treatment tank 10 gradually decreases, and after the 60th sludge treatment, the ammonia concentration is 6 mg-N / L and the nitric acid / nitrite concentration is 73 mg-N. / L. Further, the phosphoric acid concentration rapidly decreased and was about 5 mg-P / L after the 60th time, but slightly increased to 8 mg-P / L at the 70th time. For this reason, in the subsequent separation operation, about 4% / day of the residual sludge was discarded along with the disposal of the supernatant wastewater. The wastewater after the pretreatment generally had an ammonia concentration of 325 mg-N / L, nitric acid / nitrite concentration of 0 mg-N / L, and phosphoric acid concentration of 40 mg-P / L.

  After the repetition, sludge treatment in the treatment tank 10 and sedimentation separation in the separation tank 20 were further performed under the same conditions as described above. The wastewater in the treatment tank 10 has an ammonia concentration of 70 mg-N / L before starting sludge treatment, nitric acid / nitrite concentration of 58 mg-N / L, phosphoric acid concentration of 15 mg-P / L, and after anaerobic treatment, an ammonia concentration of 70 mg. -N / L, nitric acid / nitrite concentration 0 mg-N / L, phosphoric acid concentration 20 mg-P / L, after aerobic treatment, ammonia concentration 6 mg-N / L, nitric acid / nitrite concentration 73 mg-N / L, The phosphoric acid concentration was 5 mg-P / L. On the other hand, the waste water in the separation tank 20 is settled and discarded, and 415 ml of waste water supernatant (ammonia concentration 6 mg-N / L, nitric acid / nitrite concentration 73 mg-N / L, phosphoric acid concentration 5 mg-N / P) is discarded. At the same time, about 1% of the residual activated sludge was discarded. The rest is transferred to the pretreatment tank 30 and subjected to aeration treatment in the same manner as described above, followed by raw wastewater (ammonia concentration 650 mg-N / L, nitric acid / nitrite concentration 0 mg-N / L, phosphoric acid concentration 25 mg-P / L ) 415 ml was added. At this time, the wastewater in the pretreatment tank 30 had an ammonia concentration of 325 mg-N / L, a nitric acid / nitrite concentration of 37 mg-N / L, and a phosphoric acid concentration of 15 mg-P / L. After the pretreatment, the wastewater had an ammonia concentration of 325 mg-N / L, nitric acid / nitrite concentration of 0 mg-N / L, and phosphoric acid concentration of 40 mg-P / L.

It is a schematic block diagram which shows one Embodiment of the waste water treatment facility which installed the water distribution system which concerns on this invention. It is a schematic block diagram which shows other embodiment of the waste water treatment facility which installed the water distribution system which concerns on this invention.

Explanation of symbols

10: Treatment tank, 20: Separation tank, 30: Pretreatment tank, 40: Pump device 12, 32: Stirrer, 11, 31: Aeration device W, Wa: Waste water, S: Activated sludge, V1 to V50: Open / close valve

Claims (14)

A water distribution system for operating three sludge wastewater treatment facilities as a first treatment tank, a second treatment tank, and a separation tank for separating activated sludge from wastewater,
A pumping device for transferring wastewater and / or activated sludge;
A supply line capable of being transferred from the discharge port of the pump device to the first processing tank, the second processing tank, the separation tank, and the outside;
A supply control valve for controlling transfer to the first processing tank, the second processing tank, the separation tank and the outside by the supply line;
The first treatment tank, the second treatment tank, the separation tank, and the wastewater source can be transferred to the intake of the pump device, and the wastewater and activated sludge can be individually transferred from the separation tank. Line;
An intake control valve for controlling transfer from each of the first treatment tank, the second treatment tank, the separation tank, and the wastewater source by the intake line;
By driving the pump device, the waste water supplied from the waste water source is transferred together with the activated sludge in the order of the first treatment tank, the second treatment tank, and the separation tank before being discharged to the outside. A water distribution system comprising: a supply control valve; and a control unit that controls operations of the intake control valve.   2. The water distribution system according to claim 1, wherein each of the first treatment tank and the second treatment tank has a switchable oxygen supply means for adjusting wastewater to an aerobic condition.   The capacity of the second treatment tank is larger than the capacity of the first treatment tank, and the control unit is configured to supply or take in the waste water as a transfer unit with the capacity of the waste water stored in the first treatment tank. The water distribution system according to claim 1 or 2, which controls operations of the supply control valve and the intake control valve.   The supply line has four lines connected to each of the first processing tank, the second processing tank, the separation tank, and the outside, and the intake line includes the first processing tank and the second processing tank. Three lines connected to each of the tank and the waste water source, and two lines connected to the separation tank for transferring each of the waste water and activated sludge, and the control unit is one of the supply lines The wastewater and / or activated sludge is transferred by controlling the supply control valve and the intake control valve so that a line and one of the intake lines communicate with each other. Water distribution system.   Transfer of the waste water and / or activated sludge is (1) from the second treatment tank to the separation tank, (2) from the first treatment tank to the second treatment tank, and (3) from the separation tank to the outside. (4) The control unit repeats the supply control valve and the intake control valve so as to be repeated in the order of the separation tank to the first treatment tank and (5) the wastewater source to the first treatment tank. The water distribution system of Claim 4 which controls operation | movement of.   6. Waste water and activated sludge are transferred by the transfer of (1) and (2), waste water is transferred by the transfer of (3) and (5), and activated sludge is transferred by the transfer of (4). The described water distribution system.   The water distribution system according to claim 6, wherein activated sludge is also transferred in the transfer of (3).   The supply control valve is four open / close valves provided in each of the four lines, and the intake control valve is five open / close valves provided in each of the three lines and the two lines. Item 8. A water distribution system according to any one of Items 4 to 7. A water distribution system for carrying out activated sludge treatment by operating three tanks of a wastewater treatment facility as a treatment tank and a first separation tank and a second separation tank for separating activated sludge from waste water,
One pumping device for transferring wastewater and / or activated sludge;
A supply line capable of being transferred from the discharge port of the pump device to the treatment tank, the first separation tank, the second separation tank, and the outside;
A supply control valve for controlling the transfer to the processing tank, the first separation tank, the second separation tank and the outside by the supply line;
An intake line capable of being transferred from each of the treatment tank, the first separation tank, the second separation tank, and a wastewater source to an intake port of the pump device;
An intake control valve for controlling transfer from each of the treatment tank, the first separation tank, the second separation tank, and a wastewater source by the intake line;
By driving the pump device, waste water supplied alternately from the waste water source to one of the first separation tank and the second separation tank is discharged through the treatment tank together with activated sludge before being discharged to the outside. A water distribution system comprising: a control unit that controls operations of the supply control valve and the intake control valve so as to be alternately transferred to one of the separation tank and the second separation tank.   The water distribution system according to claim 9, wherein the treatment tank, the first separation tank, and the second separation tank each have an oxygen supply means capable of switching operation to adjust wastewater to an aerobic condition.   The capacity of the treatment tank is greater than the capacity of the first separation tank and the second separation tank, and the control unit determines the capacity of waste water stored in each of the first separation tank and the second separation tank. The water distribution system according to claim 9 or 10, wherein operations of the supply control valve and the intake control valve are controlled so as to be supplied or taken in as a transfer unit.   The water distribution system according to any one of claims 9 to 11, wherein the intake line has a line capable of taking activated sludge separated from waste water from each of the first separation tank and the second separation tank.   It has at least three tanks, the water distribution system according to claim 1 is provided, and the three tanks are a first treatment tank, a second treatment tank, and wastewater for activated sludge treatment. Wastewater treatment facility that operates as a separation tank that separates activated sludge from wastewater.   A water distribution system according to any one of claims 9 to 12, which has at least three tanks, wherein the three tanks are a treatment tank for activated sludge treatment, and a first tank for separating activated sludge from wastewater. Wastewater treatment facility that operates as 1 separation tank and 2nd separation tank.

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