JPS6233594A - Biological wastewater treatment method - Google Patents

Abstract

PURPOSE:To eliminate a dead water zone in the reaction vessel by sending a part of treated water into the lower end of a descending flow along with waste water in the same direction as the descending flow in the title biological treatment of waste water wherein water to be treated is circulated in the reaction vessel by the descending flow and the ascending flow. CONSTITUTION:A riser pipe 2 is vertically provided in a reaction vessel 1, water to be treated 5 at the bottom part in the reaction vessel is sent up in the riser pipe 2 by the ascending flow, the water to be treated 5 sent up to the upper part in the reaction vessel 1 is sent down between the outer wall of the riser pipe 2 and the inner wall of the reaction vessel 1 and the water to be treated 5 is brought into contact with a biocatalyst. In this biological treatment of waste water, a part of treated water 3 is sent into the lower end of the descending flow along with untreated water 6 in the same direction as the descending flow. Consequently, since formation of a dead water zone in the reaction vessel 1 is prevented, the immobilized biocatalyst packed in the reaction vessel 1 functions effectively and the concn. of the biocatalyst is substantially improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a biological wastewater treatment method for purifying wastewater using microorganisms, that is, biocatalysts.

[Conventional technology and its problems]

In biological wastewater treatment methods, by maintaining a high biocatalyst concentration per reactor capacity, it is possible to make the reactor more compact, improve solid-liquid separation, and reduce the amount of surplus sludge generated. It is possible. For this reason, it is possible to immobilize the biocatalyst by adsorbing the biocatalyst onto an inorganic carrier, encapsulating the biocatalyst with an organic carrier, or adsorbing the biocatalyst onto an inorganic carrier and then encapsulating it with an organic carrier. The biocatalyst concentration is maintained at a high concentration. Furthermore, in order to increase the biocatalyst concentration per volume of the reaction tank, it is also known to increase the amount of biocatalyst immobilized on the carrier or to increase the carrier filling rate in the reaction tank.

By the way, conventionally, a riser pipe is installed in the reaction tank, and the water to be treated at the bottom of the reaction tank is caused to rise in the riser pipe by an upward flow, and the water to be treated that has risen to the top of the reaction tank is caused to flow downward. A biological wastewater treatment method is provided in which the water to be treated is circulated in the reaction tank by descending between the outer wall of the riser pipe and the inner wall of the reaction tank, thereby increasing the contact efficiency between the biocatalyst and the water to be treated. be.

However, this method has conventionally had the following problems. In other words, when the water to be treated is circulated in the reaction tank by upward flow and downward flow, a dead area is created around the bottom inner wall of the reaction tank at the bottom of the reaction tank where the flow direction changes from downward flow to upward flow. It is formed. For this reason, even if the reaction tank is filled with immobilized biocatalyst to increase the biocatalyst concentration in the reaction tank, the immobilized biocatalyst in the dead area will not be sufficiently active, and the There has been a problem in that the filling rate of the immobilized biocatalyst, which is effective in purifying wastewater, is not sufficiently improved.

Therefore, it is an object of the present invention to provide a circulating biological wastewater treatment method in which a dead zone is unlikely to be formed in a reaction tank.

[Means for solving problems]

In order to solve the above problems, the present invention provides a biological wastewater treatment method in which water to be treated is circulated by a downward flow and an upward flow in a reaction tank as described above. A portion of the treated water along with the wastewater flows into the lower end of the counterflow in the same direction as the downward flow.

[Effect]

As a result, the immobilized biocatalyst and the water to be treated around the bottom of the reaction tank where a dead zone is likely to be formed are forcibly fluidized, so that a dead zone is not formed in the reaction tank.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of an apparatus for performing anaerobic treatment. This is a closed reaction tank 1 with a rising pipe 2, and the treated water is drawn out by overflow.

3 was caused to flow into the bottom of the reaction tank 1 by the circulation pump 4 to form an upward flow in the reaction tank 1, whereby the water to be treated 5 rose in the rising pipe 2 and rose to the upper part of the reaction tank 1. The water to be treated 5 is circulated by descending between the outer wall of the riser pipe 2 and the inner wall of the reaction tank 1 by a downward flow. and,
A part of the treated water 3 circulated by the circulation pump 4 is caused to flow into the lower end of the downward flow together with the raw water 6 in the same direction as the downward flow, and the immobilized biocatalyst around the bottom of the reaction tank 1 and the water to be treated are 5 is fluidized. At this time, it is preferable that a part of the treated water and the raw water 6 are allowed to flow evenly around the riser pipe 2 .

Figure 2 also shows a device that performs anaerobic treatment, similar to Figure 1, and this device is designed to reduce the amount of CH, Co, generated by anaerobic treatment.
A gas 8 such as No. 2 is blown into the bottom of the reaction tank 1 by a compressor 7 to form an upward flow. Then, the treated water 3 and part of the water drawn out by the overflow and the raw water 6 are made to flow into the lower end portion of the downward flow in the same direction as the downward flow.

Next, the one in FIG. 3 is an apparatus for performing aerobic treatment, in which air is blown into the bottom of the reaction tank 1 by an aeration compressor 9, thereby forming an upward flow in the reaction tank 1. It has become. Then, a part of the treated water drawn out by the overflow and the raw water 6 are made to flow into the lower end portion of the downward flow in the same direction as the downward flow.

〔effect〕

The present invention is as described above, however, the water to be treated flows around the bottom of the reaction tank where a dead area is likely to occur.

Therefore, according to the present invention, since the formation of dead zones in the reaction tank is prevented, all the immobilized biocatalysts filled in the reaction tank are effectively activated, and the biocatalyst concentration is substantially increased. effective.

Furthermore, by causing the raw water to flow into the lower end of the downward flow together with the treated water, the raw water is sufficiently mixed and agitated, which has the effect of improving the treatment efficiency especially when the concentration of the raw water is high.

[Brief explanation of drawings]

FIGS. 1 to 3 are schematic diagrams each showing an example of an apparatus for implementing the present invention. 1.1...Reaction tank, 2...Rising pipe, 3...Treated water, 5...Water to be treated, 6...Raw water Patent applicant Kubota Iron Works Co., Ltd. Same agent Kama 1) Sentence two

Claims (1)

[Claims] A riser pipe is installed in the reaction tank, and the water to be treated at the bottom of the reaction tank is made to rise in the riser pipe by an upward flow, and the water to be treated that has risen to the top of the reaction tank is caused to rise by a downward flow. In a biological wastewater treatment method in which the biocatalyst and the water to be treated are brought into contact by descending between the outer wall of a pipe and the inner wall of a reaction tank, a portion of the treated water along with the raw water is made to flow downward to the lower end of the downward flow. A biological wastewater treatment method characterized by flowing in the same direction.