JPH08103780A - Biological treatment device - Google Patents

Abstract

PURPOSE: To treat the waste water of medium concentration with high degree of performance under heavy loads by effecting, in one treatment tank, contact aeration and filtration by means of floating filter medium. CONSTITUTION: The interior of a treatment tank 10, in which raw water is supplied to the bottom thereof and the raw water flows upward, is divided into an upper section 14 and a lower section 12, and packing materials 13 or which biomembranes are deposited are provided in the lower section 12 and a filter layer 16 comprising floating filter medium is provided in the upper section 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a biological treatment apparatus for subjecting industrial wastewater (raw water) to contact aeration treatment with a biofilm and then filtering or biofiltering the treated water.

[0002]

2. Description of the Related Art Processed products obtained by processing chemical fibers such as vinylidene chloride, vinyl chloride, nylon, etc. into a string or ring,
It has been generally practiced in the past to reduce the BOD by attaching and growing a biofilm on a plastic plate or the like, using this as a filler, and subjecting raw water to contact aeration treatment to remove soluble organic components in the raw water. There is. In addition, a biological membrane is attached to an extremely small floating filter medium having a specific gravity of 1 or less, which is formed by foaming polystyrene, polypropylene, urethane resin or the like into a spherical or irregular shape having a diameter of about 3 to 10 mm to form a filter layer. Biofilm filtration is also known, in which raw water is passed in an upward flow, and similarly, soluble organic components in the raw water are removed to reduce BOD.

[0003]

The problem of the above contact aeration process is the blockage of the gap between the fillers by the biofilm excessively attached to the filler. If the film thickness of the biofilm adhering to the packing material can be adjusted to a constant value, the BOD concentration of the wastewater to which contact aeration is applied will expand to the middle concentration range, and high load operation will be possible. Since there is no adjustment means, contact aeration mainly targets low-concentration wastewater with a BOD of 100 mg / cubic or less, and the applicable range is the low-load region with a BOD load of 1 kg / m ³ · day or less. When applied to medium-concentration drainage of 100 mg / stand or more, or when operated in a high load area, the film thickness of the biofilm adhering to the packing material increases, the gap between the packing materials is blocked, and There is a risk that the supply of oxygen will be insufficient, and as a result, the quality of the treated water will deteriorate significantly.

Further, the problem of biofilm filtration is to wash the filter layer. If an efficient cleaning method with a short cleaning time and a small amount of cleaning wastewater is developed, the BOD concentration of the wastewater to be subjected to the biofilm filtration will be a medium concentration. It is possible to expand to the range, but since there is no effective cleaning method, the BOD load amount is 2 to 5 kg / m ³ ·
We are operating on a daily load, and the target wastewater is low-concentration wastewater as well as contact aeration, and if we target medium-concentration wastewater with a BOD of 100 mg / stand or more, the cleaning frequency will increase and efficient operation will not be possible, Similar to contact aeration, the gap between the floatable filter media will be blocked and the quality of treated water will deteriorate.

[0005]

The present invention was developed for the purpose of simultaneously solving the conventional problems of contact aeration and filtration or biological filtration, and the raw water is supplied to the bottom of the tank to obtain the raw water. Is divided into an upper part and a lower part, a filler having a biofilm attached thereto is provided at the lower part, and a filter layer made of a floating filter material is provided at the upper part.

[0006]

In the illustrated embodiment, 10 is a treatment tank, and raw water is supplied to the bottom of the tank by a water supply pipe 11 and flows upward in the tank.
The inside of the tank was divided into a lower part 12 and an upper part 14, and a large number of cord-like fillers 13 for contact aeration were suspended in the lower part in a rope-like shape. The installation amount of the string-shaped filler depends on the shape of the filler,
If the diameter of the string is 10 to 30 mm, 50 to 2 per 1 m ^{3 of the} tank
00m is suitable and has a biofilm attached to the surface.

A strainer 15 such as a wire mesh is provided above the tank.
Is installed, and a filter layer 16 made of a floatable filter material is provided below the filter. The buoyant filter media is buoyantly concentrated under the strainer to form a filter layer 16 on the upper portion 14 in the processing tank. The height of the filter layer is
It is made higher than the filler 13 for contact aeration. An air diffuser 17 is laid on the bottom of the tank.

In order to carry out the treatment, raw water is supplied to the bottom of the treatment tank by a water supply pipe to cause an upward flow in the treatment tank, and at the same time, air is supplied from the diffuser pipe 17 to remove biofilms adhering to the packing material 13. Stay active. When the raw water flows upward in the lower part of the treatment tank, it comes into contact with the biofilm attached to the packing material 13, and the soluble organic substances in the raw water are decomposed by the biofilm.

When the raw water flows upward in the filter layer formed by the floating filter material in the upper part of the treatment tank, SS in the raw water and the biofilm adhering to the packing material 13 excessively grow and are separated from the biofilm. Sludge is captured in the filter bed.

A biofilm may be adhered to the buoyant filter medium constituting the filter layer, in which case undecomposed organic matter in the raw water which has not been treated by contact aeration with the filler is adhered to the buoyant filter medium. The biofilm can be decomposed.

The treated water treated by the contact aeration unit and the filter layer of the floatable filter medium is taken out from the take-out pipe 18 at the upper end of the treatment tank.

Filler 13 in the lower contact aeration section in the processing tank
When excessive biofilm adheres to the filter or SS or sludge is excessively trapped in the filter layer formed by the floating filter material on the upper side and pressure loss of the filter layer increases, cleaning is performed. For cleaning, after stopping the passage of raw water, a part of the liquid in the tank is pulled out from the drain pipe 19 at the bottom of the tank, and the height of the filter layer is lowered to the position of the contact aeration section (see FIG. 2). In this state, supply air from the air diffuser at the bottom of the tank,
The floatable filter medium in the filter layer is agitated with air to flow. During the flow of the buoyant filter medium, the buoyant filter medium collides with or comes into contact with the surface of the filler 13, whereby the sludge and SS excessively trapped in the filter layer are peeled off, and also from the surface of the filler 13. Excess biofilm is stripped.

When the buoyant filter medium is caused to flow by the air from the air diffuser, the air supply is stopped, the valve of the drain pipe 19 is opened, and the liquid remaining in the tank is discharged. The sludge and SS that have peeled off are discharged outside the tank together with the liquid.

When the discharge of the liquid in the tank is completed, the valve of the drain pipe is closed, industrial water or treated water is supplied into the tank from above by the supply pipe 20, and the original water is filled. Supply to the bottom and restart operation.

If the sludge and SS cannot be sufficiently peeled and discharged in one washing, the washing is performed again after water filling.

A water flow test and a backwash test were conducted by the apparatus shown in FIG. A commercially available string-like bioloop (made by Kureha Chemical Co., Ltd., the material is vinylidene chloride) is used as the contact aeration filler, and the floatable filter material for biological filtration is made of expanded polypropylene and has a particle size of 3 to 5 mm and a specific gravity of dry. Fine particles of 0.3 to 0.5 were used in the state. The processing tank has a diameter of 400 mm and a height of 3000
A transparent column of mm is used, aeration air and raw water are supplied from the bottom of the device, a net with an opening of 2 mm or less is installed at the top of the column, and the floating filter material made of expanded polypropylene is placed under the net. 1000 mm was thrown in. 50 from the bottom of the device
0 mm above, over a height of 1000 mm, length 100
Ten 0 mm bioloops were installed vertically.
Each bioloop had a structure in which it did not touch or entangle with each other. BOD 300 to 1000 using glucose as a main substrate
mg / vertical synthetic substrate was passed through with a load of ^{3 to} 8 kg-BOD / m ³ · day per total treatment tank capacity (370 L) to attach a biofilm to the surface of the string-like bioloop of the contact aeration unit, Sludge was adhered to the floatable filter medium on the upper part. The amount of biofilm attached to the bioloop is 8 to 12 g-VSS / m, and the amount of sludge captured on the floating filter medium is 5.5 to 7 g-VSS / m.
It was m ³ . The washing was stopped once a day, the raw water supply was stopped, the liquid in the tank was drawn to the position of 1500 mm from the bottom, air was supplied from the aeration pipe for aeration, and the expanded polypropylene was made to flow to remove excess sludge. After draining the residual water in the tank, industrial water was injected from the upper part of the tank. By this washing, excess sludge and biofilm were discharged well. By these operations, the BOD concentration of the synthetic substrate was 1000 mg /
BOD10-15mg / stand, SS15mg in the high concentration range of BOD load 8kg / m ³ · day at medium concentration
/ Highly treated water below the vertical was stably obtained. The reason why highly treated water was obtained was that the biofilm adhering to the string-like packing material in the contact aeration section at the bottom of the tank could be adjusted to a constant film thickness with high activity. It is possible to remove it, and the biofilm filtration at the top of the tank captures almost completely the floating sludge generated from the contact aeration section, and captures a small amount of BOD remaining in the contact aeration section. It depends on what could be processed.

[0017]

As is apparent from the above, according to the present invention, in the contact aeration section at the lower part of the processing tank, the BO in the high load region is increased.
D decomposition, decomposition of residual BOD in the upper biofilm filtration section,
Sludge and SS are captured by filtration, and due to the combined effect of treatments with different functions, medium-concentration wastewater can be treated highly under high load. By cleaning the contact aeration filler in the lower part of the tank, the filler does not clog even when the medium-concentration wastewater is treated under high load, so that the applicable wastewater concentration and the load amount can be expanded. Furthermore, since biofilm filtration using a floatable filter medium is combined, BOD remaining due to contact aeration at the bottom of the tank, SS that could not be discharged by washing, and biofilm sludge are decomposed and captured by biofilm filtration. Therefore, highly treated water can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention during operation.

FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 in a cleaned state.

[Explanation of symbols]

 10 Treatment tank 11 Raw water supply pipe 12 Lower part of tank 13 Contact aeration filler 14 Upper part of treatment tank 15 Strainer 16 Filter layer with floating filter material 17 Air diffuser pipe 18 Treated water extraction pipe 19 Wash water drain pipe 20 For water filling Supply pipe

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C02F 3/10 ZAB A B01D 29/08 540 A

Claims (1)

[Claims] 1. A raw water is supplied to the bottom of the tank, and the inside of the treatment tank in which the raw water flows upward is divided into an upper part and a lower part, a filler having a biofilm attached to the lower part, and a filter with a floating filter material on the upper part. A biological treatment device having a layer.