JPS59139995A - Water disposal - Google Patents

Abstract

PURPOSE:To increase the amount of O2 dissolved in raw water to be treated for enhancing the power of treating BOD, in a method for bringing a liquid into countercurrent contact with gas in a fluidized bed process, by hermetically sealing a tank and holding the inner pressure of said tank at a high level. CONSTITUTION:Raw water to be treated is supplied through a water supply pipe 11 to the interior of a hermetically sealed tank 10 and circulated therein as a downward stream through a fluidized bed 13 formed from a carrier 14 having specific gravity smaller than that of water. At the same time, air is injected through a sparger pipe 15 into the raw water to be treated and brought into countercurrent contact with the raw water to be treated. Hereon, the inner pressure of the tank 10 is raised above ordinary pressure in a range below about 5kg/cm<2> by a booster. Hence, the dissolution of O2 into the raw water to be treated is acceleratd, and the dissolution ratio of O2 is held at a high level corresponding to the inner pressure and temp. of the tank 10.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a water treatment method for treating sewage, industrial wastewater, etc. containing organic substances.

Conventionally known water treatment methods of this type include an activated sludge method, a sprinkler hearth method, and a fluidized bed method. Among them, the fluidized bed method is superior to the activated sludge method and the sprinkled hearth method in that it can increase the BOD load, that is, it has a large processing capacity. This means that the amount of microorganisms growing on the surface of the carrier constituting the fluidized bed can be reduced by 10%.
This is because it is possible to more than double the amount of microorganisms, but in order to increase the amount of microorganisms in this way, the amount of BOD must be 0% by weight.
．． It is necessary to provide 5 to 1.0 times more dissolved oxygen, and for this purpose, various types of oxygen have been conventionally used. In other words, the one shown in Figure 1 is a granular carrier 2 with a large specific gravity.
The raw water to be treated is made to flow in countercurrent from the lower part into the tank 1 filled with The acid mA is dissolved in the treated raw water W in advance (see Japanese Patent Application Laid-Open No. 81660/1983). This is because it is difficult to directly supply air into tank 1 because it would impair the flow state of carrier 2, but it is not possible to simply supply air and treated raw water into tank 1 in this way. Since the direction of travel of the gas and liquid is circular, the contact time between them is short, and sufficient dissolution of oxygen cannot be expected. Moreover, since the air mixing device 4 is required, the overall structure becomes complicated.

In addition, in FIG. 2, a granular carrier 6 with an apparent specific gravity smaller than that of water is filled in the tank 5, and the treated raw water W is passed in a downward flow from the upper part of the tank 5 into the fluidized bed thus formed. At the same time, +, l=air A is directly supplied from the lower part of the tank 5 (see Japanese Patent Laid-Open No. 54-108464). This method not only eliminates the need for a gas-liquid mixing device as described above, but also has the advantage that the contact time between the gas and liquid is long because they contact each other countercurrently. Since oxygen is dissolved by pressure, the length is 40 to 50 m.
Oxygen solubility in gl statement (oxygen solubility in air alone is 10 m
Therefore, even though the surface area of the granular carrier on which microorganisms can grow is large, the amount of microorganisms that can grow is suppressed, and there is a limit to the BOD treatment capacity.

The purpose of the present invention is to increase the amount of oxygen dissolved in treated raw ice in the latter method of bringing gas and liquid into countercurrent contact, thereby increasing the BOD treatment capacity.

Accordingly, the present invention forms a fluidized bed by attaching microorganisms to a granular carrier whose apparent specific gravity is smaller than that of water and filling this carrier in a sealed tank, and in which the upper part of the tank is placed inside the fluidized bed. The treated raw water is circulated as a countercurrent, and air is blown into the treated raw water from the lower part of the tank while keeping the pressure inside the tank high to increase the amount of oxygen dissolved in the treated raw water and carry out water treatment. What is done is 4'[.

Hereinafter, the water treatment method of the Wood invention will be explained in detail with reference to the drawings.

FIG. 3 shows an example of an apparatus suitable for carrying out the method of the present invention, in which 10 is a closed type tank, and the tank 10 is
A water supply pipe 11 for supplying treated raw water is provided inside and above the tank 1o, and a wood pipe 12 for treated water is provided at the lower end of the tank 1o. In addition, the inside of the -1 tank 1o is filled with a large number of granular carriers 14 having an apparent specific gravity smaller than that of water, and these carriers 14 with microorganisms attached to their surfaces create a fluid flow for treating the treated logs. A floor 13 is formed. A waste air pipe l5 for supplying oxygen-enriched air into the raw water to be treated is arranged in the lower part of the inside of the tank 1o, and this air diffuser pipe l5 is connected to an air source l7 such as fire through an oxygen enrichment device l6.
-C is connected to -C. This oxygen enrichment device 16 is equipped with an oxygen enrichment membrane in which an oxygen selective membrane made of a silicon-based polymer membrane with a high oxygen permeability coefficient is attached to a porous support membrane. The reflux tube 1 is designed to increase the oxygen concentration by removing carbon dioxide, carbon dioxide, etc.
It is connected to the upper part of the tank 10 via the tank 8, and is configured so that the gas recovered within the tank 10 can also be recycled.

Note that 18 in the figure is an exhaust pipe for discharging nitrogen, carbon dioxide, etc. removed from the air.

When water treatment is performed using the above treatment equipment, water supply bamboo 1
The treated raw water is supplied into the tank 10 through the fluidized bed 13 formed of a carrier 14 having a small apparent specific gravity.
At the same time, the oxygen enrichment device l6
Oxygen-rich air with an increased oxygen concentration is blown into the treated raw water through the aeration pipe 15, and the treated raw water and the oxygen-rich air are brought into contact with each other in a self-flowing manner. At this time, the pressure inside the tank 10 is approximately 5 kg/c due to the pressure equipment (not shown).
The pressure is raised to above normal pressure within the range of m' or less. This promotes the dissolution of oxygen into the raw water to be treated, and the oxygen solubility becomes high depending on the tank internal pressure and tank internal temperature.

According to experiments, the temperature inside the tank was set at 20°C. The pressure inside the tank is 2Kg.
/cm', it was possible to dissolve oxygen at about three times the pressure.

Since microorganisms grow sufficiently on the surface of the rod 14 in the treated raw water with an increased degree of dissolved M, the decomposition of organic matter is promoted by contact between these microorganisms and the treated raw water, and the treatment of the treated raw water is carried out. The treated water is then discharged through the drain pipe 12.

The gas recovered in the second part of tank 10 is sent through reflux 18 to oxygen enrichment device 16, where it is mixed with outside air.
After the nitrogen and charcoal liquor scum contained therein are removed and the oxygen concentration is increased, it is again blown into the tank through the diffuser 15.

As described in detail above, according to the present invention, the treated raw wood and air are brought into contact with each other in a countercurrent manner, and the air is supplied with the pressure inside the tank increased, so that By increasing the amount of oxygen dissolved into the liquid, processing capacity can be significantly increased.

[Brief explanation of the drawing]

1 and 2 are block diagrams of an apparatus used to implement the conventional processing method, and FIG. 3 is a block diagram of an apparatus used to implement the processing method of the present invention. 10... Tank, l3... Fluidized bed, 14... Carrier.

Claims (1)

[Claims] l. Microorganisms are attached to a granular carrier with an apparent specific gravity smaller than that of water, and this carrier is filled in a sealed tank to form a fluidized bed. The treated raw water is poured downward into this fluidized bed from the second part of the tank. Water treatment is carried out by circulating the water as a stream and blowing air into the raw water to be treated from the F part of the tank while keeping the pressure inside the tank high to increase the amount of oxygen dissolved in the raw water to be treated. Water treatment methods. 2. After enriching the oxygen in the air by removing nitrogen, carbon dioxide, etc. with a chuan enrichment device, the chuan enriched air is blown into the treated raw water. The water treatment method according to item 1. 3. The gas recovered from the tank is refluxed to the oxygen enrichment device,
3. The water treatment method according to claim 2, wherein the oxygen concentration is increased in the oxygen enrichment device 1 together with external air and 4) is resupplied into the tank.