JPS6023875B2 - Biofilm-attached filler for wastewater treatment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filler used for biological treatment of wastewater, in which microorganisms are attached to the filler in the form of a film, and wastewater is treated by contacting the biofilm.

There are two types of biofilm treatment methods for wastewater: a fixed bed type and a fluidized bed type. The filling material for the fixed bed type is plate-shaped, corrugated plate-shaped, or mesh-shaped plastics such as vinyl chloride and polyethylene. In addition, granular materials such as sand and anthracite are used as fluidized bed fillers.

These fillers do not allow biofilm to adhere for a long period of time from the start of wastewater treatment operations, and even if biofilm does adhere, once it peels off, it takes a long time for it to attach again, and no biofilm is attached. The disadvantage was that the quality of the treated water deteriorated significantly during this period. The purpose of the present invention is to eliminate the drawbacks of the prior art as described above, to enable biofilm to adhere quickly at the start of operation, to quickly regenerate even if the biofilm detaches, and to always provide stable and good quality treated water. The objective is to provide a filler material that can be formed by immobilizing a microbial inoculum on the surface of a carrier.

That is, the filler according to the present invention is characterized in that a paint containing microorganisms is applied to the surface of a carrier such as plastic, sand, or anthracite.

The microorganism may be a pure culture or a mixed culture of bacteria, mold, yeast, actinomycetes, algae, and the like.

Paints that can be used in the present invention include acrylic resin paints, epoxy resin paints, acrylimide resin paints, acrylamide resin paints, styrene resin paints, bran derivative paints, polyurethane resin paints, and vinyl resin paints. Any paint can be used as long as it solidifies when left at room temperature or heated to an extent that does not kill microorganisms, and does not release microorganisms into the liquid after solidification.

When microorganisms are mixed in such a paint, applied to the surface of a carrier, and the paint film is solidified, a filler in which microorganisms are immobilized can be obtained.

The microorganisms fixed in this way act as seed bacteria, and a biofilm quickly attaches to the surface of the filler at the start of wastewater treatment.
Furthermore, even if peeling occurs during operation, the biofilm is quickly regenerated because of the presence of seed bacteria. Next, the present invention will be described in detail based on Examples, but the present invention is not limited thereto.

Example 1: Acrylamide-based resin paint containing acrylamide and N,N'-methylenebisacrylamide as main components 2: Add sludge that has been acclimatized with N company food wastewater so that the M ratio SS is 500 females/day This paint was then applied to a vinyl chloride corrugated board.

The thickness of the paint applied may be on the order of 10 mm to 1 mm. Filling material obtained in this way was placed in the third warming tank at a filling rate of 60%.
Two pieces of filling material were filled in each interval. Using this ant cage, wastewater from 80D300 females was continuously treated for 30 days with a residence time of 6 hours, and the BOD of the treated water was measured. The results are shown in FIG. During the period, O/Sleeve treatment was performed at pH 7 and dissolved oxygen 3 to 5. Until the third day, the water quality was poor, but from the fourth day, the biofilm had grown to the point that it was clearly visible to the naked eye, and good treated water was obtained.

As a conventional method, the same wastewater was treated under the same conditions except that a paint containing microorganisms was not applied to the filler and sludge was added to the blast tank as seed sludge at a rate of 2000 mc/〆.
As shown in the figure.

At first, the treated water became cloudy and the water quality fluctuated and was not stable.Biofilm began to form on the 8th day, but the water quality improved thereafter. Example 2 Pure culture of Bacillus subtilis
The cells were centrifuged, concentrated, and mixed with acrylamide resin paint at a concentration of 1 cell/secretion.

Apply this paint to sand with a diameter of 0.5 and apply it to 30 qo at 35 qo.
It solidified in minutes. The thickness of the paint to be applied may be about 10 to 1 thick, and the temperature at which it solidifies is not limited thereto. This sand was filled into the aeration tank of No. 1 with a filling rate of 30%, and was fluidized by aeration, with an expansion rate of 50% and a BOD of 200.
Misaki/The wastewater from the production process of Company K was continuously treated with a residence time of 5 hours. Figure 3 shows the results after 30 days of operation.

The treated water became stable on the second day, and the growth of biofilm was also good.

Conventional methods do not apply paint containing microorganisms to the sand.
Figure 4 shows the results of treating the same wastewater under the same conditions except that sludge was added to the tank at a rate of 2000 o/l.

Biofilm started to adhere on the 5th day, after which the water quality improved. As can be seen from Examples 1 and 2, in the present invention, biofilm adheres to the filler material quickly, and even if the biofilm peels off during long-term operation, the inoculum is fixed by the paint, so the biofilm can be regenerated. was carried out quickly and consistently good treated water was obtained.

On the other hand, in the conventional method, not only was the biofilm attached slowly, but also the biofilm became too thick during long-term operation and was likely to peel off due to the tethering force, resulting in unstable treated water quality. In the above example, an acrylamide resin paint was used, but
Equally good results can be obtained using other paints.

[Brief explanation of drawings]

Figure 1 is a diagram of the daily change in BOD of treated water when wastewater is subjected to fixed-bed contact aeration treatment using the filler of the present invention.
The figure shows the diurnal variation of BOD of treated water in the case of fixed bed type catalytic explosion treatment using the conventional method, and Figure 3 shows the treated water in the case of fluidized bed type warm air treatment of wastewater using the filler of the present invention. 800 of
FIG. 4 is a diagram showing the daily change in BOO of treated water in the case of fluidized bed warm air treatment according to the conventional method. Figure l Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A biofilm-adhering filler for wastewater treatment, characterized in that a paint containing microorganisms is applied to the surface of a carrier such as plastic, sand, anthracite, etc. 2. The filler according to claim 1, which uses a paint containing pure cultured microorganisms or mixed cultured microorganisms.