JP4124902B2 - Wastewater treatment equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wastewater treatment apparatus, and more particularly, to a wastewater treatment apparatus for efficiently reducing excess sludge generated from wastewater treatment equipment and removing phosphorus.
[0002]
[Prior art and problems to be solved by the invention]
The standard activated sludge method is popular as the most common sewage treatment method. However, since it has become difficult to secure a disposal site for surplus sludge every year, the treatment and disposal of surplus sludge generated in large quantities from wastewater treatment facilities has become an urgent issue. Furthermore, in recent years, it is expected that small-scale sewage treatment will be the center, and in order to reduce construction costs and maintenance costs, a treatment method that generates less sludge is eagerly desired. For this reason, sludge is reduced by anaerobic digestion of sludge, but there is a problem that maintenance management is complicated, for example, methane gas is generated or desulfurization operation is required in the generated gas. It was.
[0003]
On the other hand, the conventional standard activated sludge method is mainly intended to remove BOD in sewage, and is insufficient for removing phosphorus. As a method for removing phosphorus, a coagulation sedimentation treatment is known, but this method has a big problem that excess sludge increases. In recent years, a biodephosphorization method using polyphosphate-accumulating bacteria that accumulates polyphosphate in the body under anaerobic and aerobic conditions has been modified by providing an oxygen-free part in the aeration tank of the standard activated sludge method. It has been adopted. However, in this method, phosphate is released from the sludge during the sludge concentration process and sludge storage, so that high-concentration phosphorus is eluted in the return water from the sludge treatment process and returned to the water treatment system. Therefore, it can be said that the phosphorus removal rate seen in the whole treatment plant is not always good.
[0004]
Then, this invention aims at providing the waste water treatment apparatus which can reduce the generation amount of the excess sludge in a waste water treatment facility, and can also perform the removal of phosphorus efficiently.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the wastewater treatment apparatus of the present invention comprises a sludge concentration digester for storing excess sludge generated in a wastewater treatment facility and reducing the amount of solids by the self-oxidation action of microorganisms, and the sludge concentration digestion A membrane separation device for concentrating sludge in the tank; and a path for returning the membrane separation water separated by the membrane separation device to the wastewater treatment facility, and further comprising phosphorus in the membrane separation water. It is characterized by having a dephosphorization device for removing water.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a schematic system diagram showing an embodiment of the waste water treatment apparatus of the present invention, and shows a basic configuration of the present invention. That is, the sludge concentration digestion tank 11 for storing and reducing excess sludge generated in the wastewater treatment equipment 10 in the wastewater treatment equipment 10, and the membrane separation device for concentrating the sludge in the sludge concentration digestion tank 11 12 and a dephosphorization device 13 for removing phosphorus in the membrane separation water separated by the membrane separation device 12.
[0007]
The sludge concentration digester 11 concentrates the excess sludge A generated by the wastewater treatment such as the activated sludge method to a high concentration, for example, about 3% by the membrane separator 12, and the concentrated sludge is converted to DO, ORP, water temperature. The main purpose is to reduce the amount of solids by the oxidative action of microorganisms and to obtain concentrated sludge B by maintaining the environment such as stirring intensity in a substantially constant state for a long time.
[0008]
That is, although it is in a stable living environment at a high concentration, it is in an environment where the nutrient source is scarce, so microorganisms in the activated sludge undergo autooxidation, thereby reducing the amount of sludge. At this time, the organic matter in the sludge is consumed by auto-oxidation of microorganisms to become water, carbon dioxide, etc., and phosphorus is released into the liquid. Therefore, methane or the like is not generated, and it is not necessary to perform a special process on the generated gas from the sludge concentration digester 11, so that maintenance management is facilitated.
[0009]
The sludge concentration and digestion tank 11 is provided with an aeration apparatus and a stirring apparatus similar to those in a normal aeration tank, and the DO, ORP, etc. are kept substantially constant by controlling these. . In a cold district or the like, a heating device can be provided as necessary.
[0010]
The membrane separator 12 takes in the activated sludge C in the sludge concentration digester 11 and performs solid-liquid separation so that the sludge concentration becomes about 2 to 5%, and returns the concentrated sludge D into the sludge concentrate digester 11. At the same time, the separated water (membrane separation water E) is returned to the wastewater treatment facility 10. Thus, by concentrating the sludge with the membrane separation device 12, the sludge concentration in the sludge concentration digester 11 can be reliably maintained at a high concentration, and the sludge concentration digester 11 with a small volume can retain solids. The time can be increased and sludge can be reduced effectively. The system of the membrane separator 12 is arbitrary, and various types can be used as long as the sludge can be concentrated.
[0011]
Moreover, although the dephosphorization apparatus 13 is provided as needed in the middle of the path | route which returns the membrane separation water E to the waste water treatment facility 10, the membrane separation water E isolate | separated with the membrane separation apparatus 12 comprises sludge. Since the organic matter, TN, and TP that have been used are contained at a high concentration, an effective dephosphorization treatment can be performed by performing a dephosphorization operation on the membrane separation water E. Since the membrane separation water E contains high-concentration phosphorus and there is almost no suspended solids, various methods such as a coagulation-precipitation method, an adsorption method, and a MAP method can be employed as the dephosphorization method. In addition, the coagulation sedimentation method requires a small amount of chemical solution, the adsorption method does not easily block the adsorption tower, and the MAP method has advantages such as the advantage of reusing the fixed phosphorus compound.
[0012]
The membrane separation water (dephosphorization water F) dephosphorized by the dephosphorization apparatus 13 is returned to a predetermined position of the wastewater treatment facility 10 in a state containing almost no phosphorus and solid matter.
[0013]
Thus, by providing the waste sludge treatment facility 10 with the surplus sludge treatment facility including the sludge concentration digester 11 and the membrane separation device 12, the amount of solid matter of the surplus sludge A generated in the waste water treatment facility 10 is, for example, 30. It can be set as the concentrated sludge B reduced to about%, and the disposal can be performed easily. In addition, by providing the dephosphorization device 13 that is a phosphorus removal facility in the path for returning the membrane separation water E to the wastewater treatment facility 10, an effective dephosphorization process utilizing the characteristics of the membrane separation water E can be performed. .
[0014]
FIG. 2 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility of a standard activated sludge method. A wastewater treatment facility to which the standard activated sludge method is applied is formed by a sand basin 21, a dust remover 22, a first sedimentation basin 23, an aeration tank 24, a final sedimentation basin 25 and a chlorine mixing basin 26, and flows into the sand basin 21. The sewage G is treated by a predetermined procedure and discharged as treated water H from the chlorine mixing pond 26.
[0015]
At this time, the sedimentation basin 21 generates the sedimentation sand J, the dust remover 22 the shearing sand K, the first sedimentation tank 23 the primary sedimentation sludge L, and the final sedimentation tank 25 the surplus sludge A. A predetermined amount of the sludge extracted from the final sedimentation basin 25 is returned to the upper end of the aeration tank 24 as return sludge M.
[0016]
Such a wastewater treatment facility is provided with the above-described sludge concentration digester 11, membrane separator 12 and dephosphorizer 13, and surplus sludge A from the final sedimentation basin 25 and initial sedimentation sludge from the first sedimentation basin 23. By storing and treating L in the sludge concentration digester 11, the excess sludge generated in the wastewater treatment facility can be extracted as, for example, concentrated sludge B reduced to about 30%.
[0017]
Moreover, phosphorus can be effectively removed by performing a dephosphorization process with the dephosphorization apparatus 13 with respect to the membrane separation water E generated when the sludge is concentrated by the membrane separation apparatus 12. Furthermore, conventionally, the sludge concentrating tank detachment liquid separated in the sludge concentrating tank has been returned to the sedimentation basin 21, but the membrane separation water E (dephosphorized water F) contains almost no solids. Since it can return to 24, the burden from the sedimentation basin 21 to the first sedimentation basin 23 can be reduced.
[0018]
FIG. 3 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility for biological dephosphorization. In the following description, the same reference numerals are given to the same components as those of the embodiment, and the detailed description thereof is omitted.
[0019]
In the biological dephosphorization method, the above-mentioned standard activated sludge method cannot sufficiently remove phosphorus, and the treated water H is discharged while containing a considerable amount of phosphorus. The inflow portion of the aeration tank 24 is an anoxic tank 24a, and the latter half is an aerobic tank 24b, thereby removing phosphorus. That is, when microorganisms go through an anaerobic-aerobic state, phosphorus is removed by utilizing a phenomenon in which phosphorus is consumed in an aerobic state in excess of the amount of phosphorus released in the anaerobic state.
[0020]
The above-described sludge concentration digester 11, membrane separation device 12 and dephosphorization device 13 are attached to such a wastewater treatment facility, and the removal of phosphorus is further effectively performed by reducing sludge and removing phosphorus. It can be carried out. For example, in the conventional biological dephosphorization method, sludge excessively ingested phosphorus releases phosphorus again during operations such as concentration and dehydration, and the released phosphorus is returned to the water treatment system along with the sludge return water. As a result, phosphorus eventually flows out into the secondary treated water.
[0021]
On the other hand, as shown in the present embodiment, since the sludge that has excessively ingested phosphorus is concentrated by the membrane separation device 12, phosphorus released from the sludge can be taken into the membrane separation water E. It contains phosphorus at a higher concentration than the membrane separation water in the standard activated sludge method. Therefore, by introducing the membrane separation water E into the dephosphorization apparatus 13 and performing the dephosphorization process, the amount of phosphorus returned to the anoxic tank 24a is greatly reduced. The outflow can be suppressed.
[0022]
In FIG. 4, anaerobic tank 31, anaerobic tank 32 and aerobic tank 33 are connected as treatment tanks, and nitrification denitrification is performed by returning a part N of activated sludge from aerobic tank 33 to anaerobic tank 32. FIG. 2 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility of a circulation type nitrification / denitrification method that also removes nitrogen components contained in sewage.
[0023]
Even in such a waste water treatment facility of the circulation type nitrification / denitrification method, by adding the sludge concentration digester 11, the membrane separator 12 and the dephosphorizer 13, the surplus can be achieved without making a large-scale modification of the existing facilities. The amount of sludge generated can be greatly reduced, and phosphorus can be efficiently removed in addition to nitrogen.
[0024]
Furthermore, treatment methods other than the standard activated sludge method as shown in the above embodiments, for example, step aeration method, oxidation ditch method, long-time aeration method, batch activated sludge method, rotary disk method, contact aeration method, By combining the above-described sludge concentration digester 11 and membrane separation device 12 with an air filter method or the like, the amount of excess sludge can be greatly reduced, and furthermore, the removal of phosphorus is also effective by adding a dephosphorization device 13. Can be done.
[0025]
FIG. 5 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility using a membrane separation activated sludge method that has attracted attention in recent years. In the membrane separation activated sludge method, the sewage G pretreated by the sand basin 21 and the dust remover 22 is flowed into the aeration tank 42 through the adjustment tank 41, and the sludge in the aeration tank 42 is removed by the membrane separation device 43. Solid-liquid separation is performed, and membrane separation water is discharged as treated water H. In this embodiment, an example in which the membrane separation device 43 is installed in the aeration tank 42 is shown. Moreover, the adjustment tank 41 is provided as needed when the flow volume fluctuation | variation of a sewage is large.
[0026]
In such a wastewater treatment facility of the membrane separation activated sludge method, by attaching the sludge concentration digestion tank 11, the membrane separation device 12 and the dephosphorization device 13, the amount of sludge discharged from the facility can be greatly reduced, Phosphorus removal can also be performed effectively.
[0027]
Further, when the aeration tank 42 performs intermittent aeration, the excess sludge A is extracted from the aeration tank 42 to the sludge concentration digestion tank 11 during the aerobic operation, thereby extracting the sludge excessively ingested with phosphorus. Therefore, phosphorus can be removed more effectively.
[0028]
FIG. 6 shows the biological dephosphorization in the membrane-separated activated sludge method, so that the inflow part of the aeration tank 42 is an anoxic tank 42a and the latter half part is an aerobic tank 42b, as in the embodiment shown in FIG. The example which applied this invention to what was shown is shown. Further, in this embodiment, the membrane separation device 43 is installed separately from the aeration tank 42, the sludge P is extracted from the aeration tank 42 through the piping, and the returned sludge Q after solid-liquid separation is returned to the inflow portion 42a through the piping. ing.
[0029]
Also in this embodiment, the excess sludge A is drawn from the aerobic tank 42b to the sludge concentration digester 11, concentrated with the membrane separator 12, and sludge is reduced by the self-oxidation of microorganisms in the sludge concentrate digester 11. By doing this, the amount of sludge solids can be greatly reduced. Similarly to the above, phosphorus can be efficiently removed by the dephosphorization apparatus 13 by combination with biological dephosphorization.
[0030]
【The invention's effect】
As described above, according to the wastewater treatment apparatus of the present invention, it is possible to efficiently reduce the excess sludge generated in the wastewater treatment facility, and to efficiently remove phosphorus. It can also be easily applied to existing wastewater treatment facilities.
[Brief description of the drawings]
FIG. 1 is a schematic system diagram showing an example of a wastewater treatment apparatus according to the present invention.
FIG. 2 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility of a standard activated sludge method.
FIG. 3 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility for biological dephosphorization.
FIG. 4 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility for a circulating nitrification denitrification method.
FIG. 5 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility using a membrane separation activated sludge method.
FIG. 6 is a system diagram showing an embodiment in which the present invention is applied to a wastewater treatment facility that performs biological dephosphorization in a membrane separation activated sludge method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Waste water treatment equipment, 11 ... Sludge concentration digester, 12 ... Membrane separation device, 13 ... Dephosphorization device, 21 ... Sand basin, 22 ... Dust remover, 23 ... First sedimentation basin, 24 ... Aeration tank, 24a ... Oxygen-free Tank, 24b ... Aerobic tank, 25 ... Final sedimentation tank, 26 ... Chlorine-mixing pond, 31 ... Anoxic tank, 32 ... Anaerobic tank, 33 ... Aerobic tank, 41 ... Adjustment tank, 42 ... Aeration tank, 42a ... None Oxygen tank, 42b ... Aerobic tank, 43 ... Membrane separation device

Claims (2)

A sludge concentration digester for storing excess sludge generated in a wastewater treatment facility and reducing the amount of solids by auto-oxidation of microorganisms, a membrane separation device for concentrating sludge in the sludge concentrate digester, and A wastewater treatment apparatus comprising a path for returning the membrane separation water separated by the membrane separation apparatus to the wastewater treatment facility. The waste water treatment apparatus according to claim 1, further comprising a dephosphorization device for removing phosphorus in the membrane separation water.

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