JPS596983A - Treatment of water formed by treating waste water with biomembrane - Google Patents

Abstract

PURPOSE:To easily and sufficiently remove turbidity, etc. from treated water, by returning separated sludge from a precipitation tank to a tank for treatment with biomemebranes at the final stage of the group of tanks for treatment with biomembranes in a manner such that MLSS in said tank is held above 800mg/l. CONSTITUTION:Waste water 2 is treated by successively sending it from a tank 1a for treatment with biomembranes at the first stage to the next ones 1b, 1c, 1d at the following stages and then sent from the tank 1d for treatment with biomembranes at the final stage to a precipitation tank 3. The tanks 1a, 1b, 1c, 1d for treatment with biomembranes are packed with reticulated catalytic substrates and entirely aerated by a sparger 9 to perform the treatment with biomembranes. During the treatment of the waste water 2, separated sludge is returned from the precipitation tank 3 through a pipe line 4 to the tank 1d for treatment with biomembrane at the final stage in a manner such that MLSS in the tank 1d for treatment with biomembranes at the final stage is held above 800mg/l.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating wastewater treated with a biofilm.

Wastewater treatment using the biological method has been widely practiced in the past, but this method has the disadvantage that the turbidity of the treated water is greater than that in the activated sludge method.

Therefore, in order to improve this problem, increasing the contact time between the biofilm and wastewater, that is, the residence time, is being considered, but this would require very large equipment and would be economically disadvantageous. be.

The present invention was invented in view of the shortcomings of the conventional methods, and its purpose is to provide a method that can extremely simply and sufficiently remove the turbidity, etc. of treated water that has undergone whole biofilm treatment of wastewater. It's about trying to get it.

A method for treating treated water obtained by biofilm treatment of wastewater according to the first invention that achieves this object is based on ML in the final biofilm treatment tank of a group of biofilm treatment tanks arranged in multiple stages.
The method is characterized in that the separated sludge is returned from the settling tank to the final stage of the biofilm treatment tank so that the SS is maintained at 8 o on 1 g/Q or more, and the wastewater according to the second invention is The treatment method for biofilm-treated treated water is to remove all of the separated sludge from the sedimentation tank so that the MLSS in the air aeration tank placed between the biofilm treatment tank and the settling tank is maintained at soo no. 9 or higher. It is characterized by being returned to the air aeration tank.

Hereinafter, the first invention will be described in detail based on the flow sheet of FIG. 1.The first stage biofilm treatment tank (]a)
From the second stage biofilm treatment tank (lb).

Wastewater (2) is sequentially sent to (lc) and (ld) for treatment.

And from the final stage biofilm treatment tank (1d) to the sedimentation tank (3)
Water is sent to

In addition, biofilm treatment tanks (la), (lb), (1,
c) and (ld) are filled with a reticulated contact base material and subjected to biological treatment while being aerated over the entire surface by an aeration device (9).

In the present invention, when completely treating wastewater (2) in this way, MLS in the final stage biofilm treatment tank (ld)
The conduit (4
) The separated sludge is returned from the settling tank (3) to the final stage biofilm treatment tank (1d).

With this returned sludge, the sludge sedimentation in the settling tank (3) can be converted into interfacial sedimentation, and the turbidity of the treated water (5) can be reduced.
- Can be removed satisfactorily.

In other words, in conventional biofilm treatment methods, the inflow MLSS to the sedimentation tank is 100 μ/flood culm degree, and although free sedimentation is possible, interfacial sedimentation cannot be achieved, and therefore the treated water is However, according to the present invention, it is possible to perform interfacial sedimentation, promoting the co-precipitation effect of turbidity components, and increasing the frequency of contact between turbidity components and living organisms. This amplification promotes the bioadsorption effect and can sufficiently remove turbidity.

The turbidity components in the treated water (5) include minute aerobic bacteria and anaerobic bacteria that have detached from the contact substrate, and turbidity components in the wastewater that have not been captured by the biofilm. According to the present invention, any of these can be removed without being limited to a specific one.

In the present invention, the biofilm treatment tank may be provided in either a watering ρ bed type treatment tank, an immersed ρ bed type treatment tank, or a single rotating disk type treatment tank, and not only treatment tanks of the same type may be arranged in multiple stages, but also treatment tanks of different types may be installed. The processing t'i may be arranged in multiple stages.

It goes without saying that the separated sludge from the settling tank must be returned to the final stage biofilm treatment tank, but if it is returned to the previous stage biofilm treatment tank without being returned in this way, this Not only does the returned sludge become finer due to the contact substrate and the like, and the sludge settling rate is significantly reduced, but also a new turbidity component is added, making it impossible to obtain the effects of the present invention described above.

In the figure, (6) indicates the excess sludge transfer pipe, and (7) indicates the discharge water.

Next, the second invention will be described in detail based on the flow sheet of FIG. 2.7 The apparatus shown here has an air aeration treatment tank ( 8)
The basic difference is that the air aeration treatment tank (8) has a MLSS of 800 mm.
/I! , from the sedimentation tank (3) to the pipe (
The separated sludge is returned via 4).

Note that the air aeration treatment tank herein means one in which the treated water from the biofilm treatment tank is simply aerated using a total aeration device.

In this way, in the present invention, as in the first invention described above, the sedimentation tank (3) is connected to the final stage biofilm treatment tank (ld).
Rather than returning the separated sludge from the sludge, it is returned to a separately provided air aeration treatment tank (8), thereby achieving a more sufficient turbidity removal than that achieved by the first invention.

If this happens, it will be returned to the final stage biofilm treatment tank (ld).

In this tank (Id), the returned sludge is atomized by the contact base material, etc., and the sludge settling rate is completely reduced, whereas the air aeration process is 4'1! (8) This is based on the fact that such atomization of the returned sludge does not occur in the return to the sludge.

In the present invention, the biofilm treatment tank may not be provided in multiple stages but may be provided in one tank, and the biofilm treatment tank is a watering ρ bed type treatment tank as in the first invention.

Immersion vertical treatment tank 9-rotating disk type treatment (can be installed in any of the tanks)

Next, examples related to the first invention and the second invention described above and comparative examples thereof will be described.

BOD is 120/R, COD is 65■/Q, SS is 1
When wastewater with a transparency of 20 cm/n and a transparency of 5 cm was treated using the flow sheet shown in Figure 1, the effluent water (BOD of
, COD, SS.

The visibility and sludge settling rate in the settling tank (3) were as shown in row A of Table 1.

At this time, M in the final stage biofilm treatment tank (ld)
Sedimentation tank (
The separated sludge from 3) was returned.

The same wastewater as the wastewater in the embodiment of the first invention was treated according to the flow sheet shown in row 2, and the BOD, COD, SS, transparency of the effluent (7), and sludge settling in the settling tank (3) were evaluated. The speeds are now shown in row B of Table 1.

At this time, the MLSS in the air aeration treatment tank (8) is 8.
Separated sludge was returned from the settling tank (3) so that the amount of sludge was 0.00 to 1000.

Comparative Example 1 Separated sludge from the settling tank (3) was transferred to the biofilm treatment tank group (la-1
The BOD, COD, SS, and transparency of the effluent water (7) were treated under the same conditions as in the embodiment according to the first invention except that the water was not returned to d).
The result is as shown in line A of .

Comparative Example 2 Separated sludge from the settling tank (3) is transferred to the final stage biofilm treatment tank (l
B of the effluent water (7) was treated under the same conditions as in the embodiment according to the first invention except that it was returned to the first stage biofilm treatment tank (1a) without being returned with d.
OD, COD, SS, visibility and sedimentation tank (3
) The sludge settling rate was as shown in row B of Table 2.

Table 1 Table 2 As is clear from this, in the examples according to the first invention and the second invention, the transparency of the discharged water (7) is greater than that in Comparative Example 1.2, and therefore It can be seen that the turbidity of the treated water (5) can be more effectively removed.

Furthermore, the transparency in the embodiment of the second invention is greater than that in the embodiment of the first invention. It can be seen that the turbidity of the treated water (5) can be more effectively removed by using the method. Naori OD, COD
, 55 as well.

As described above, according to the first and second inventions, the turbidity of treated water obtained by biofilm treatment of wastewater can be removed very easily and sufficiently, and the BOD, COD, and 55
There is also a treatment method that can remove it more fully.

[Brief explanation of drawings]

FIG. 1 is a wastewater treatment flow sheet diagram for an embodiment according to the first invention, and FIG. 1 and FIG. 2 are wastewater treatment flow sheet diagrams for an embodiment according to the second invention. (la-1d) Biofilm treatment tank (2): Waste water (3) Sedimentation tank (4): Pipe for returning separated sludge (5) Treated water (7) Discharge water (8): Air aeration Processing tank

Claims (2)

[Claims] (1) Among the biofilm treatment tank groups arranged in multiple stages, the MLSS in the final stage biofilm treatment tank is 80 Cyng.
A method for treating wastewater subjected to biofilm treatment, characterized in that the separated sludge is returned from the settling tank to the biofilm treatment tank at the final stage so that the temperature is maintained at /f1 or higher. (2) Return the separated sludge from the settling tank to the air aeration tank so that the MLSS in the air aeration tank placed between the biofilm treatment tank and the settling tank is maintained at 8007q/R or higher. A method for treating wastewater treated with a biofilm, characterized by the following.