JPH06304571A - Treatment of waste water - Google Patents

Abstract

PURPOSE:To eliminate a mixing device for mixing a mechanical separation residue with a membrane separation concentrate in a waste water treating method wherein solid matter in a waste water is removed by a mechanical separation device and a flocculant is injected into the separated liquid to treat it by membrane separation. CONSTITUTION:In a waste water treating device in which after solid matter in waste water 1 is removed by a mechanical separator 2, a flocculant 3 is injected into the separated liquid to flocculate the residual solid matter and colloid and a part of soluble materials and the formed flocs are separated by a membrane separation device, a membrane separation concentrate 7 contg. the flocs is circulated through the mechanical separator 2 to separate and concentrate them together with the solid matter in the waste water 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to various wastewater (industrial wastewater,
Domestic wastewater such as human waste, sewage, septic tank sludge separation liquid, etc.)
Regarding the processing method of.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional wastewater treatment method. After removing most of the solids in the wastewater 1 with a mechanical separator 2 such as a centrifuge, the separated liquid is a flocculant (organic or inorganic condensing agent such as a sulfuric acid band (aluminum sulfate) or a polymer flocculant). By injecting 3 in the flocculation reactor 4,
The solid matter, colloid, and a part of the soluble substance remaining in the separated liquid are taken into the floc, and the floc is separated by the ultrafiltration or microfiltration membrane separation device 5. Separation residue 8 and membrane separation device 5 from the mechanical separation device 2.
The concentrated liquid 7 containing agglomerated flocs is discharged from the device, and these are mixed by the mixing device 9 and treated by the sludge treatment device 10.

[0003]

The above-mentioned conventional wastewater treatment method has two discharge systems of a mechanical separation residue and a membrane separation concentrate, as shown in FIG.
A mixing device is required for the mixing process, which complicates the device configuration and complicates operation management.

The present invention is intended to provide a wastewater treatment method capable of solving the above problems.

[0005]

According to the method for treating wastewater of the present invention, a solid matter in a wastewater is removed by a mechanical separator, and then a coagulant is injected into the separated liquid to leave a residual solid matter, colloid and solubility. A wastewater treatment method in which a part of a substance is flocculated and separated by membrane separation is characterized in that a membrane separation concentrate containing agglomerated flocs is circulated through a mechanical separation device.

[0006]

In the present invention, as described above, the membrane separation concentrated liquid is circulated through the mechanical separation device, and the solid matter in the waste water and the floc floc are mixed, so that the mixing device which has been conventionally required is omitted. And the operation management is simplified. Further, the flocs in the membrane separation concentrate are also concentrated by the mechanical separator, so that the volume of sludge (mechanical separation residue and flocs) generated is reduced.

According to the present invention, as described above, the solid composition and coagulation flocs in the undiluted solution of waste water are mixed and processed by the mechanical separation apparatus, so that the apparatus configuration and operation management are simplified. The factor that determines the success or failure of the treatment method is whether or not the original purpose of the mechanical separation device, that is, the function of separating and concentrating the solid matter in the stock solution, can be maintained at the same level as the conventional method. Aggregated flocs are extremely difficult to dehydrate due to their strong water retention, and there is a possibility that they may be adversely affected by mixing them with wastewater. Therefore, this point was examined by the following experiment.

(1) Experimental sample (target liquid): septic tank sludge (Sampling the one that is carried into A human waste treatment plant), SS
Concentration 12300ppm, (2) Experimental equipment, conditions ... Mechanical separation (batch centrifuge, centrifugal rotation speed 3000 rpm, 10 minutes), coagulant (sulfuric acid band, injection rate 300ppm, pH 6.5 adjusted with NaOH, chemical mixture is jar) Conducted with a tester, stirring blade rotation speed 150 rpm,
Mixing time 5 minutes) Membrane separation (uses a membrane separation tester that circulates the circulating liquid by a circulation pump between the stock solution storage tank to which N ₂ is supplied and the membrane permeation section shown in FIG. 2), ultrafiltration membrane ,
Fractional molecular weight 40,000, material polyacrylonitrile, permeation pressure 2 kg / cm ² , liquid temperature 20-22 ° C), (3) Experimental method …… After separating and concentrating septic tank sludge with a batch centrifuge to remove solids, A coagulant is injected into the separated liquid with a jar tester, and then the mixed liquid is subjected to membrane separation. 1 for membrane separation
Concentrate to / 10, mix the concentrate with the septic tank sludge at a volume ratio of 1:10, and then separate and concentrate again with a batch centrifuge. The concentration of the concentrated solution SS in the batch centrifuge was compared when the flocculation flocs (membrane separation concentrated solution) were not mixed. (4) Experimental results: Concentrated solution SS concentration of 42100 ppm without mixing floc, 42700 with mixing
At ppm, there is almost no difference between the two. Therefore, it was confirmed that even if the flocculation flocs were mixed, the original separation and concentration function of the mechanical separation device was not hindered.

As described above, according to the present invention, the mechanical separation residue and the membrane separation concentrate, which have been conventionally required, can be mixed without causing any trouble in the separation and concentration function of the mechanical separation device. The device is omitted, the operation and management is simplified, and the volume of sludge (mechanical separation residue and coagulated flocs) generated is reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIG. Most of the solid matter in the wastewater 1 is removed by a mechanical separator 2 such as a centrifuge, and a coagulant (organic or inorganic condensing agent such as a sulfuric acid band (aluminum sulfate) or a polymer condensing agent) is added to the separated liquid. By injecting 3 in the flocculation reactor 4, a part of the solid matter, colloid, and soluble substance remaining in the separated liquid is taken into floc floc. Then, flocculated flocs are separated by the ultrafiltration or microfiltration membrane separation device 5, and the treated water 6 is discharged to the outside of the system. On the other hand, the concentrated liquid 7 containing agglomerated flocs separated by the membrane separator 5 is circulated to the mechanical separator 2 where the agglomerated flocs are separated and mixed with the solid matter in the wastewater. The mechanical separation residue (sludge) 8 in which the solid matter and the flocculated flocs are concentrated is treated by a sludge treatment device 10.

As described in the section "Operation", the solid flocs in the waste water and the floc aggregates separated by the membrane separator 5 are sufficiently separated and concentrated in the mechanical separator 2.

Therefore, in the present embodiment, the mixing device for mixing the mechanical separation residue and the membrane separation concentrate can be omitted, and the operation management can be simplified, and the generation can be prevented. The volume of sludge to be used can be reduced.

[0013]

As described above, according to the present invention, after the solid matter in the wastewater is removed by the mechanical separation device, a coagulant is injected into the separated liquid to remove the residual solid matter, colloid and soluble substances. In a wastewater treatment method in which a portion is flocculated and separated by membrane separation, by circulating a membrane separation concentrate containing floc through a mechanical separation device, a mixing device that was conventionally required can be omitted. ,
In addition, the operation can be simplified. Further, since the floc of flocs is separated and concentrated by the mechanical separation device together with the solid matter in the wastewater, the volume of the generated sludge can be reduced.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a system diagram of a membrane separation test device used for confirming the effect of the present invention.

FIG. 3 is a system diagram of a conventional wastewater treatment method.

[Explanation of symbols]

 1 Wastewater 2 Mechanical Separation Device 3 Coagulant 4 Coagulation Reaction Device 5 Membrane Separation Device 6 Treated Water 7 Membrane Separation Concentrated Liquid 8 Mechanical Separation Residue 10 Sludge Treatment Device

Claims (1)

[Claims] 1. After removing the solid matter in the wastewater by a mechanical separation device, a coagulant is injected into the separated liquid to coagulate and flocculate a part of the remaining solid matter, colloid and soluble substances, and to form a membrane. In the wastewater treatment method of separating by separation, a membrane separation concentrate containing coagulated flocs is circulated through a mechanical separation device.