JPS58159894A - Treatment of sewage by fluidized bed type apparatus - Google Patents

Abstract

PURPOSE:To improve the treating performance for sewage in a biological treatment method for sewage by a fluidized bed type apparatus, by using the moldings produced by fixing sludge with a polymer resins a fluid media. CONSTITUTION:Thermosetting resin is added to the cake obtd. by dehydrating the excess sludge produced in treatments of sewage, night soil, etc. and after granulation, the mixture is heated and cured, whereby moldings are obtd. The resins used are phenolic, melamine and urea resins, and are added to the sludge in the form of a precondensate. The resulted spherical sludge moldings have strength and low apparent specific density and float in water usually; therefore, if a prescribed amt. of such moldings are added in an aeration tank, the moldings form a fluidized and suspended state easily. If sewage is supplied continuously into such aeration tank, all the surfaces of the moldings have tachiness on account of aerobic microorganisms, and the treating performance is thus increased.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluidized bed biological treatment method for wastewater.

Conventionally, the activated sludge method has been the mainstream method for biologically treating wastewater, but recently, fixed bed treatment methods such as the single rotating disk method and the contact warming method have also become quite popular. The fixed bed system has advantages such as easy maintenance, low sludge generation, high nitrification efficiency of element II, and easy denitrification, but on the other hand, the treatment efficiency per unit volume is low. There are drawbacks.

Recently, as a method to increase the treatment efficiency of fixed bed treatment, research has been conducted on a method of treating sludge by using fine particles such as sand or anthracite and attaching sludge to the particles while fluidizing them. However, it is difficult to uniformly disperse and fluidize fine particles such as sand and anthracite, and even if the particles are fluidized well, the adhesion of sludge to each particle is poor, and 3% of the added particles The reality is that it only adheres to about 1 of these.

The present inventor has completed the present invention as a result of intensive research into a fluidized bed biological treatment method that eliminates the above-mentioned drawbacks.

That is, the present invention is a fluidized bed sewage treatment method characterized in that a molded product of sludge solidified with a polymer resin is used as the fN moving medium in the fluidized bed sewage treatment method.

In the method of the present invention, the molded product used as the fluidizing medium is prepared by adding cake IC thermosetting V1 fat obtained by dewatering surplus sludge generated in the treatment of sewage, night soil, etc., and heating and hardening it after granulation. It is something. l to use! 1Iil fats include phenolic resins, melamine AT fats, urea resins, etc., and all of them are used as sludge 1cIla in the form of initial condensates.
As for the amount of lie added.

The amount is approximately 50 to 500%, preferably 100 to 300%, relative to dry sludge. For granulation, a transfer type granulator is generally used. Adding resin to the cake and homogenizing Cfi,
After preliminary drying, it is granulated.

In addition, Active Hiro is used as a moisture content regulator during granulation.

Add hydrogen, incineration ash, etc. as necessary. The granulated molded product is heat-cured at 100 to 200°C for about 30 minutes to 5 hours. The granulated molded product is usually spherical and has a diameter of about 5 to 30 mm, preferably about 5 to 10 mm.

The spherical sludge molded product obtained by molding as described above has a strength of 1, has a low apparent specific gravity, and usually floats on water.

When a spherical sludge molded product, for example, 5 ma+- is used and a predetermined amount is added to the aeration tank, the molded product is light and easily forms a fluidized floating state. In such an aeration tank, the BOD is approximately 1
When 20 ppm sewage was continuously passed through, the BOD of the treated water started to decrease from about 2 days, and after 3 days, the BOD of the treated water started to decrease.
The OD decreased to approximately 20 pP''.The spherical sludge molded product was taken out and the surface was observed, and the surface of the molded product was all sticky, and the sticky material was observed under a microscope.

It was confirmed that it was an aerobic microorganism. Or microorganisms were attached to most of the particles. It is surprising that a microbial film layer was formed so quickly and the treatment performance improved without the addition of seed sludge. Although the reason for this is not fully clear,9 the particles used as the fluid medium in the method of the present invention are formed from sludge, and although this sludge is dead, its chemical structure is the same as that of microorganisms. The present invention will be specifically explained below with reference to Examples.

Example Excess sludge dewatered cake generated from human waste treatment (water content 185
%) IC) Limeterol melamine to dried sludge, -
Add C150 and mix uniformly, pre-dry to lower the moisture content, apply to a granulator to granulate particles with an average particle size of 6゛°φ0, and then heat harden at T150''; the particle size is approx. A spherical sludge molded product with a diameter of 5 mm and a diameter of 4 L was obtained.

This spherical sludge molding (apparent specific gravity 0.55) 50
The sample was placed in an aeration tank with a volume of 11, and air was circulated at 4 j/h. Sewage with a BOD of 120 pPDl was continuously passed through this aeration tank at a flow rate of 0.3 J/h. From the second day after water flow started, the BOD of treated water decreased to 55Pp! 11, and after 5 days the treated water BOD was 21 Pp! I Ic decreased. Furthermore, as a result of observing the surface of the spherical sludge molding, sticky aerobic microorganisms were found to be growing. Thereafter, as a result of continuously passing wastewater for about two hours, the BOD of the treated water was maintained at approximately 20 ppm, and a good treatment condition could be continued.

On the other hand, for comparison, using this aeration tank, #-shaped sludge molded product 50
The same volume of anthofsite was added in place of the chlorine, and air was swirled in the same manner, and sewage with a BOD of 120 ppm was treated under the same conditions as above. As a result, the BOD of the treated water did not decrease even after two weeks had passed after the wastewater was passed through. So I added 1kg of seed sludge for about 2 weeks, and as a result, the BOD of the treated water was about 7.
It decreased to 0 ppm+. Although the treatment was continued thereafter, the BOD of the treated water did not fall below 70 ppm.

Patent applicant: Unitika Co., Ltd.

Claims (1)

[Claims] (1) A fluidized bed biological treatment method for sewage, characterized in that a molded product of sludge solidified with a polymer resin is used as the fluid medium.