KR880002150B1 - Treatment method for wast water - Google Patents

Abstract

A biological method for treating high BOD waste water is characteryzed in that an original waste water having high concentration of BOD is diluted with filtered waste water treated in the fixed-bed contact-oxidizing tank filled with aerobic microorganisms.

Description

Treatment method of wastewater containing high concentration of BOD

Explanatory drawing of the flow which shows one example of embodiment of this invention.

* Explanation of symbols for the main parts of the drawings

1: contact oxidation tank 2: suspension separation device

5: filler 20: raw wastewater

21: clarification treatment 22: dilution waste water

23: treated water of the contact oxidation tank

The present invention relates to a method for effectively treating wastewater containing a high concentration of BOD components by biological treatment.

Conventionally, an anaerobic fermentation method or a dilute activated sludge method has been used as a method for biologically treating wastewater containing a high concentration of BOD components. In the anaerobic fermentation method, wastewater is stored in a fermentation tank, and the BOD component in the wastewater is decomposed into methane and carbon dioxide by the action of anaerobic microorganisms, but has the following drawbacks. First, it is necessary to lengthen the residence time, so the size of the device becomes larger. Second, odors such as hydrogen sulfide and corrosive gas generated simultaneously with methane cause problems in the environment and materials.

In addition, the dilution activated sludge method oxidizes and decomposes the BOD component by the action of anaerobic microorganisms by diluting the raw waste water with industrial water or groundwater.However, when the industrial water is used as the dilution water, the water ratio becomes high. Problems such as ground subsidence occur, and a large installation area is required.

On the other hand, as a part of biological treatment, a fixed phase contact oxidation method in which wastewater is brought into contact with and treated with a filler layer in which an aerobic microorganism is grafted on the surface has been attracting attention. The fixed-phase catalytic oxidation method has various advantages such as easy maintenance, low generation of sludge, and low operating cost. Therefore, wastewater containing high concentrations of BOD components can be used instead of the above-described anaerobic fermentation method or dilute activated sludge method. Its use is also desired for processing.

However, treatment of high concentrations of BOD such as 1,000 mg as 0/1 or more wastewater by this fixed-phase catalytic oxidation method greatly reduces the treatment effect. The reason for this is that biological inhibition due to high concentration of the raw waste water, sludge generated in the voids in the filler layer increases, short pass of the water to be treated, a decrease in the rate of oxygen movement, and the like.

The present invention solves the above problems and provides a method for efficiently treating wastewater containing high concentrations of BOD components by a catalytic oxidation method. In treating raw raw water containing BOD components, part of the clarified water obtained by installing a turbidity separation device at the rear end of the fixed-phase contact oxidation tank and treating the treated water of the fixed-phase contact oxidation tank with the turbidity separation device. The present invention relates to a method for treating wastewater containing a high concentration of BOD components, which is mixed with the raw wastewater and dilutes the BOD concentration of the raw wastewater, and supplies the diluted wastewater to the fixed-phase contact oxidizing tank.

Next, the present invention will be described in detail with reference to the drawings.

The drawing is an explanatory view of a flow showing an example of the embodiment of the present invention, and the top of the contact oxidation tank 1 and the suspension separation device 2 are provided by installing the turbidity separation device 2 at the rear end of the contact oxidation tank 1. The lower part of is connected to the connection pipe 3.

This contact oxidation tank 1 arrange | positions the support phase 4 in the lower part, and fills the filler 5, such as gravel, crushed stone, an inorganic, organic molding, on the upper part, Similarly, the air outlet pipe 6 having a large number of small holes and the treated water pipe 7 having a large number of small holes are laid so that the air in the form of bubbles is evenly discharged from the air outlet pipe 6. By flowing the treated water from the water pipe 7 to be treated in an upward flow while flowing out, the BOD component in the water to be treated is biooxidized and removed by the action of aerobic microorganisms grafted to the surface of the total material 5. It is taken out from the top. In some cases, the water to be treated may be introduced into the down stream from the upper portion of the filler 5, and the treated water may be taken out from the lower portion.

In addition, the suspended solids separating device 2 shown in the drawing has a scraping machine 9 at the lower part of the settling tank 8, and the sludge collecting machine 9 is slowly rotated by the motor 10 to be stabilized. Is taken out by the slurry pump 11 from the lower part of the sedimentation tank 8, and the clarification water is discharged from the upper part of the sedimentation tank 8, but the flotation separation unit 2 separates the pressure flotation. As long as the purified water is obtained by separating the turbidity such as an apparatus, a filtration apparatus, and a centrifuge, any one can be used. In addition, a dispensing tank 12 is provided at the rear end of the suspension separation apparatus 2, and a first-class bank 13 is installed inside the dispensing tank 12 to clarify the flow from the connection pipe 3 '. A part of the treated water is collected from the first-class bank 13 and configured to be circulated to the raw water adjustment tank 15 using a recycle pipe 14.

In addition, the blower 16 and the air outlet pipe 6 communicate with the air inlet pipe 17, and the raw water adjustment tank 15 and the treated water pipe 7 are pumped by the pump 18. Communicate with). In addition, an air outlet pipe 6 'having a plurality of small holes is provided in the lower part of the raw water adjustment tank 15 to communicate the air outlet pipe 6' and the blower 16 with the air inlet pipe 17 '.

Next, the processing method of the present invention will be described.

First, the raw waste water 20 containing the high concentration of BOD component is introduced into the raw water adjustment tank 15, and the clarified treated water 21 flowing from the first bank 13 of the distribution tank 12 is recirculated. It is made to flow into the raw water adjustment tank 15, and the blower 16 is driven to introduce air from the air inlet pipe 6 ', and the raw waste water 20 and the clarification treatment water 21 are mixed.

In addition, stirring the wastewater in the raw water adjustment tank 15 with air is due to the following reasons other than the purpose of mixing the raw wastewater 20 and the clarification treatment water 21.

In other words, if the wastewater in the raw water adjustment tank 15 remains without supplying oxygen, the wastewater may become anaerobic and generate odors. Therefore, the waste water is introduced into the air so as not to be anaerobic. It is not preferable to use an agitator or the like for mixing the raw waste water 20 and the clarified treated water 21 because air is introduced into the raw water adjustment tank 15 for the above reason.

In addition, in the present embodiment, when the raw waste water 20 and the clarified treated water 21 are mixed, the raw water adjusting tank 15 is used, for example, by directly mixing the clarified treated water 21 in the inlet pipe of the raw waste water 20. This raw water adjustment tank 15 can also be omitted.

The lower portion of the oxidizing tank 1 is brought into contact with the treated water inlet pipe 19 and the treated water distribution pipe 7 by driving the pump 18 for the dilution waste water 22 in which the concentration of BOD is reduced by this mixing. The air flows from the air outlet pipe 6 evenly in the form of fine bubbles in the air from the blower 16 at the same time. Since the aerobic microorganisms grow on the surface of the filler 5, the BOD component in the dilute wastewater 22 can be biooxidized by the action of this aerobic microorganism, and the treated water 23 which lowered the BOD by this oxidation contacts. It is obtained from the upper part of the oxidation tank 1.

Since this treated water 23 contains a large amount of surplus microorganisms, etc. peeled from the filler 5, this treated water 23 is sent to the turbidity separating apparatus 2 through the connection pipe 3, where It is settled and the clarification process water 21 is obtained. In addition, the sediment settled in the lower part of the turbidity separating device 2 sometimes drives the slurry pump 11 to dewater with a dehydrator (not shown). In addition, the clarified treated water 21 flowing from the upper part of the suspended matter separating device 12 is introduced into the bonsai tank 12 using the connection pipe 3 ', and a part of the clarified treated water is added to the raw water adjusting tank 15 as described above. ) And the remainder is taken out of the system as treated water.

Next, the mixing of the raw wastewater 20 and the clarified treated water 21 according to the present invention will be described. The greater the amount of the clarified treated water 21 and the greater the dilution rate, the more the treatment effect of the contact oxidation tank 1. Rises. However, as the dilution rate is increased, the capacity of the pump 18 and the suspended matter separation device 2 needs to be increased, thereby increasing the equipment cost. Therefore, the most economical dilution ratio may be used according to the BOD amount of the raw wastewater and the BOD target value of the treated water, and the BOD concentration of the dilution wastewater may be set to an appropriate concentration of 1,000 mg as O / 1 or less.

In the present invention, since diluting the raw waste water 20 with the clarified treated water 21 can reduce the concentration of the raw waste water without increasing the turbidity of the raw waste water, the BOD can avoid biological inhibition by the high concentration. In addition, since the amount of liquid increases, the ascending flow rate in the contact oxidation tank 1 increases, and as a result, it is possible to effectively prevent clogging of the eye holes of the filler 5. In addition, by treating dilution wastewater which has reduced the BOD concentration of the raw wastewater, the amount of sludge generated with respect to the flow rate of the contact oxidation tank 1 can be reduced, and these effects are mutually strengthened, thereby greatly reducing the treatment effect of the contact oxidation tank 1. I can raise it. Furthermore, since the present invention uses clean treated water in the system as dilution water of the raw waste water, the cost for securing dilution water from outside the system, such as industrial water or groundwater, does not increase.

Next, examples will be described to clarify the effects of the present invention.

BOD 6,000 mg O / 1, COD 5,600 mg as O / 1 in which glucose, urea, and the like were dissolved in water was treated using the experimental apparatus under the following conditions.

(1) Experiment apparatus

① Raw water adjusting tank diameter 0.8m, height 1.2m (capacity 0.5㎥)

② Contact oxidation tank diameter 0.5m, height 4.0m Filler inorganic filler Particle diameter 20-30㎜ Filler advice 3m

③ Sedimentation tank diameter 0.5m, height 2.5m

④ Distribution tank diameter 0.15m, height 1m

(Capacity 0.015㎥)

(2) Processing conditions

① The present invention

12.5 l / H of raw waste water and 75 l / H of clarified treated water obtained from the distribution tank are mixed and diluted in a raw water adjusting tank to pass 87.5 L / H of this distilled waste water from the bottom of the contact oxidizing tank to the upstream, and at the same time, 3N㎥ from the bottom of the contact oxidizing tank. Air of / H was introduced. The obtained turbidity in the treated water was removed from the settling tank, 12.5 l / H of the clarified treated water was taken out of the system as treated water through a distribution tank, and the remaining 75 l / H was circulated through the raw water adjustment tank. Furthermore, the wastewater of the raw water adjustment tank was mixed and stirred with 1 Nm 3 / H air.

The above treatment was carried out for one month and the results of treatment when stable were shown in the first table.

② Conventional method

12.5l / H of raw water was once received in the raw water adjustment tank, and 12.5l / H of raw water was passed through the ascending flow from the bottom of the contact oxidation tank at the same time, and 3Nm 3 / H of air was introduced from the bottom of the contact oxidation tank. The turbidity in the treated water obtained was removed from the settling tank, and 12.5 l / H of the clarified treated water was taken out of the system through a distribution tank.

In addition, as in the present invention, the wastewater of the raw water adjustment tank was mixed with 1 Nm 3 / H of air.

The result of the treatment when the above treatment was performed for one month and stabilized is shown in the first table.

[Table 1]

As can be seen from the first table, even the same amount of raw waste water supply is superior to the conventional method, and the present invention has excellent treatment effect and the present invention does not block the eye hole so much that the contact oxidizer is not cleaned of the filler layer once a week. However, in the conventional method, since the eye hole of the contact oxidation tank is severely clogged, the filler layer has to be washed once a day.

Claims (1)

In the treatment of raw wastewater containing high concentrations of BOD components in a fixed bed contact oxidation tank filled with aerobic microorganisms on the surface, a suspension separation device is installed at the rear end of the fixed bed contact oxidation tank to fix the fixed phase contact. A portion of the clarified water obtained by treating the tank's treated water with the turbidity separation device is mixed with the raw waste water to dilute the BOD concentration of the raw waste water and supply the dilute waste water to the fixed-phase contact oxidizing tank. How to treat a waste water.

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