JPH07155784A - Organic wastewater treatment method - Google Patents

Abstract

(57) [Summary] [Structure] The treated water 4 is supplied to the biological reaction tank 2 to be biologically treated, and the biologically treated water 7 is UF-treated by the membrane device 3.
In the organic wastewater treatment method in which solid-liquid separation is performed using a membrane or an MF membrane, a coagulant 5 is added to the pretreatment facility or the biological reaction tank 2 to aggregate soluble organic substances and phosphorus contained in the water 4 to be treated. [Effect] Since the concentration of the soluble organic substances and phosphorus compounds supplied to the membrane device is reduced, clogging of the membrane is prevented,
It is possible to obtain a stable membrane permeation flow rate for a long period of time without performing regular chemical cleaning.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating organic wastewater such as human waste and septic tank sludge.

[0002]

2. Description of the Related Art Generally, human waste and septic tank sludge are treated in human waste treatment facilities. The properties of what is input to the night soil treatment facility vary depending on the mixing ratio of septic tank sludge, but it is still high-concentration organic wastewater,
In the human waste treatment facility, treatment is performed by a treatment method including a biological treatment process for purifying with activated sludge and a solid-liquid separation process for separating activated sludge and treated water. In the solid-liquid separation process, separation membranes such as microfiltration membranes and ultrafiltration membranes have come to be used in place of conventional methods that rely on the difference in gravity such as sedimentation and centrifugation, and good treated water quality can be obtained. It has become possible to be.

[0003]

However, in the case of the solid-liquid separation method using a separation membrane such as a microfiltration membrane or an ultrafiltration membrane as described above, the concentration of soluble organic matter contained in the organic wastewater is When it is high, there is a problem that the soluble organic substances tend to cause clogging of the pores of the membrane. Further, human waste and the like contain phosphate ions, ammonium ions, calcium ions, magnesium ions and the like, and the calcium phosphate generated from these may cause clogging of the pores of the membrane. Therefore, there is a problem that the membrane must be regularly cleaned with the chemical solution.

The present invention is intended to solve the above problems, and it is an object of the present invention to obtain a stable membrane permeation flow rate for a long period of time without regularly cleaning the membrane with a chemical solution.

[0005]

In order to solve the above problems, the present invention introduces water to be treated into a pretreatment facility to perform a pretreatment for removing fibers and foreign matters, and the pretreated The treated water is supplied to the biological reaction tank to biologically treat the biodegradable substance with the activated sludge in the tank, and the biological treated water is supplied to the membrane device to supply the UF membrane or MF to the membrane device. In the organic wastewater treatment method in which solid-liquid separation is performed using a membrane, a coagulant is added to the pretreatment facility or the biological reaction tank to aggregate soluble organic substances and phosphorus contained in the water to be treated.

Further, in the present invention, the chromaticity of the membrane-permeated water that has permeated the UF membrane or the MF membrane is used as an index of the concentration of the soluble organic matter,
A coagulant is added so that the chromaticity is 500 degrees or less.

[0007]

With the above structure, by adding the coagulant to the pretreatment facility or the biological reaction tank, the soluble organic substances and phosphorus in the water to be treated are aggregated and supplied to the membrane device, that is, to the liquid that permeates the membrane. Since the concentration of the soluble organic substances and phosphorus compounds contained in the membrane device is reduced, clogging of the membrane in the membrane device is prevented. This prevents the membrane permeation flow rate from decreasing.

[0008]

EXAMPLES Examples of the organic wastewater treatment method of the present invention will be described below with reference to the drawings. FIG. 1 is a flow chart for explaining an embodiment of the present invention, in which a dehydrator 1 as one of pretreatment facilities, a biological reaction tank 2 for maintaining a high concentration of activated sludge, a separation membrane such as a UF membrane or an MF membrane. The membrane devices 3 provided with are arranged in this order, and the membrane device 3 can return the water to be treated in the device 3 to the biological reaction tank 2.

In this structure, when treating organic wastewater such as human waste and septic tank sludge, the water to be treated 4 is introduced into a receiving tank (not shown) as a pretreatment facility, and an inorganic coagulant or polymer coagulant is introduced. Water to be treated 4 by adding a coagulant 5
The soluble organic substances and phosphorus contained therein are aggregated. Then, the treated water 4 containing the aggregate is sent to the dehydrator 1,
In the dehydrator 1, after the aggregates are removed together with the fiber components and foreign matters contained in the treated water 4, the treated water 6 from which the fiber components and aggregates are removed is supplied to the biological reaction tank 2.

In the biological reaction tank 2, the water to be treated 6 supplied from the dehydrator 1 is mixed with the activated sludge in the tank, and the biodegradable BOD component, COD, which is a biodegradable substance in the water to be treated 6 is mixed.
Biologically treat components, nitrogen compounds, etc. Since the BOD component is also partially removed by adding the flocculant in the pretreatment step, when performing denitrification, methanol as a BOD source is added to the biological reaction tank 2 as necessary for biological treatment. I do. This biologically treated biologically treated water 7 is sent to the membrane device 3.

Then, in the membrane device 3, the biological reaction tank 2
The treated water 7 sent from the above is loaded on a separation membrane, which is a UF membrane or an MF membrane, and solid-liquid separated into a suspension 8 such as activated sludge and the membrane permeated water 9. The suspension 8 remaining in the membrane device 2 is returned to the biological reaction tank 2, and the membrane-permeated water 9 from which the suspension 8 is removed is taken out as treated water.

FIG. 2 is a flow chart for explaining another embodiment of the present invention, in which a biological reaction tank 10 for maintaining a high concentration of activated sludge and a membrane device 11 provided with a separation membrane such as a UF membrane or an MF membrane are used. The membrane devices 11 are arranged in order, and the water to be treated in the device 11 can be returned to the biological reaction tank 10.

In this configuration, when treating organic wastewater such as human waste or septic tank sludge, the water to be treated 12 is introduced into a receiving tank (not shown), and the fiber components and foreign matters in the water to be treated 12 are introduced. Etc. are removed and then supplied to the biological reaction tank 10.

In the biological reaction tank 10, when the treated water 12 is mixed with the activated sludge in the tank and denitrification is performed, the treated water 12 may be added while adding methanol as a BOD source as needed. Biodegradable BOD components, COD components, nitrogen compounds, etc., which are biodegradable substances, are biologically treated. Then, to the biologically treated water 13 that has been biologically treated, an aggregating agent 14 that is an inorganic coagulant or a polymer aggregating agent is added to the biologically treated water 13 in the same manner as in the above-described example, Aggregate soluble organic substances and phosphorus.

Then, the biologically treated water 13 containing aggregates
To the membrane device 11, and the UF membrane or the MF membrane solid-liquid separates into the suspension 15 such as activated sludge and the membrane permeated water 16, and the suspension 15 remaining in the membrane device 11 is separated into the biological reaction tank 10
And the membrane permeated water 16 is taken out as treated water. At this time, since most of the soluble organic substances represented by COD components are colored, the chromaticity of the membrane permeated water 16 is measured, and the chromaticity is used as an index of the soluble organic substance concentration in the aggregation step. By feeding back, the addition amount of the coagulant 14 is adjusted so that the chromaticity becomes 500 degrees or less. This ensures aggregation and removal of soluble organics and phosphorus.

As described above, the soluble organic substances and phosphorus in the water to be treated are aggregated by the aggregating agent, and the concentration of the soluble organic substances and phosphorus compounds supplied to the membrane device is lowered, whereby the membrane device It is possible to prevent the membrane from being clogged and prevent the membrane permeation flow rate from decreasing.

[0017]

As described above, according to the present invention, a coagulant is added to the pretreatment facility or the biological reaction tank to coagulate the soluble organic substances and phosphorus in the water to be treated, and the dissolution is supplied to the membrane device. By reducing the concentration of the organic compound and the phosphorus compound, it is possible to prevent the membrane from clogging in the membrane device, so that it is possible to obtain a stable membrane permeation flow rate for a long period of time without performing regular chemical solution cleaning. In addition, the maintenance of the membrane device is facilitated, and the deterioration of the membrane due to the chemical solution can be prevented.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of an organic wastewater treatment method of the present invention.

FIG. 2 is a flowchart showing another embodiment of the organic wastewater treatment method of the present invention.

[Explanation of symbols]

 2 Biological reaction tank 3 Membrane device 4 Treated water 5 Flocculant 7 Biologically treated water 9 Membrane permeate 10 Bioreactor 11 Membrane device 12 Treated water 13 Biologically treated water 14 Flocculant 16 Membrane permeate

Claims (2)

[Claims] 1. Activated sludge in a tank is introduced by introducing the water to be treated into a pretreatment facility for pretreatment to remove fibers and foreign matters and supplying the pretreated water to a biological reaction tank. In the organic wastewater treatment method, the biologically degradable substance is biologically treated by the method, and the biologically treated water is supplied to the membrane device to perform solid-liquid separation by the UF membrane or the MF membrane provided in the membrane device. A method for treating organic wastewater, which comprises adding a flocculant to a pretreatment facility or a biological reaction tank to flocculate soluble organic substances and phosphorus contained in water to be treated. 2. The chromaticity of the membrane-permeated water that has permeated through the UF membrane or the MF membrane is used as an index of the concentration of the soluble organic substance, and the chromaticity is 5
The method for treating organic wastewater according to claim 1, wherein a coagulant is added so that the temperature is not more than 00 degrees.