JPH0729105B2 - Water treatment method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a water treatment method for biologically treating an aqueous solution, and particularly to a water treatment method suitable for wastewater treatment.

"Prior art and its problems" As one of biological wastewater treatment methods, microorganisms are supported on particles, and the particles (hereinafter referred to as microorganism-supported particles) are fluidized in a treatment tank to perform wastewater treatment. There is a fluid suspension type processing method.

FIG. 2 shows an example of an apparatus for carrying out a fluid suspension type processing method, in which reference numeral 11 is an outer cylinder. The outer cylinder 11 has a bottomed cylindrical shape, and an inner cylinder 12 is coaxially provided inside the outer cylinder 11. The inner cylinder 12 has a cylindrical shape with an open upper end and a lower end. An aeration member 13 located below the inner cylinder 12 is provided below the outer cylinder 11 so that the gas pressurized by the blower 14 is aerated. The water to be treated in this device is flowing as shown by the arrow in the figure.

Conventionally, in the fluidized suspension type wastewater treatment method, only either the microorganism-supporting particles that are heavy to be treated or the microorganism-bearing particles that are lighter than the water to be treated have been used.

When the wastewater is treated using particles having a large specific gravity, the particles are mainly floated by the ascending flow in the inner cylinder 12 and are lowered by the liquid flow in the outer cylinder part.

When using particles having a small specific gravity, the particles are charged between the outer cylinder 11 and the inner cylinder 12 to prevent the particles from floating due to the downward flow, and the particles are suspended in the water to be treated between the inner and outer cylinders. I was trying to do it.

However, in the above-mentioned conventional wastewater treatment method, in order to suspend the microorganism-supported particles in the water to be treated, the water to be treated must be made to flow at a high speed, and there is a problem that the cost of operating the apparatus increases. In addition, in such a conventional wastewater treatment method, when a large amount of particles are added, a part of the particles settles and does not flow and suspend, or does not flow at all, or completely floats and comes into contact with wastewater. However, the amount of particles that can be effectively suspended is limited, and as a result, the efficiency of wastewater treatment cannot be improved. In particular, many particles having a specific gravity of more than 1 that can be conventionally used are those having a specific gravity of 2 or more such as sand, activated carbon and anthracite.
Since the specific gravity of water is considerably heavier than 1, there is a drawback that the circulating fluid energy becomes large.

In order to deal with such a problem, the present inventors have prepared a floating granule that can be adjusted to an apparent specific gravity (apparent specific gravity in a state of being impregnated with water) that is quite close to that of water, and that has an excellent ability to support microorganisms. developed. This floating granule is composed of a core material having an apparent specific gravity smaller than that of the solution to be treated and a lyophilic porous powder having a specific gravity larger than that of the solution to be treated, and the core material is coated with the porous powder. And a mixture of a core material and a porous powder. This floating granule can be adjusted to have a specific gravity almost equal to that of water and can be easily suspended in the water to be treated, so that the above problem can be addressed.

However, when such a floating granule is actually manufactured, if the specific gravity is strictly controlled, there is a problem that the production yield is deteriorated. Therefore, if the control of the specific gravity of the granules is loosened, the dispersion of the weight of the granules will increase, and in order to sufficiently suspend all the microorganism-supporting particles in the water to be treated and provide them for wastewater treatment, a wastewater treatment device Had to be controlled delicately, which made it difficult to operate the device.

"Means for solving the problem" Therefore, in the water treatment method of the present invention, as a treatment tank, a treatment tank in which microbial-supported particles having an apparent specific gravity of about 1 to 1.3 in the state of being impregnated with water are added. , Provided with treatment tanks into which microorganism-supporting particles having an apparent specific gravity of about 0.7 to 1 are placed, and performing water treatment, and microorganism-supporting particles used in these treatment tanks in a state in which they cannot be fluidized and suspended due to the reason described below. From each tank, or a fixed amount is regularly extracted from each tank, the extracted microorganism-carrying particles are subjected to shearing force to remove the enlarged biofilm to regenerate the particles,
The regenerated microorganism-supporting particles are separated by specific gravity to obtain the above-mentioned 2
The above problem was solved by returning to one of the processing tanks of the type.

"Example" Hereinafter, the water treatment method of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a schematic configuration of a treatment apparatus suitable for carrying out the water treatment method of the present invention. In the figure, reference numerals 1 and 2 are treatment tanks, reference numeral 3 is a regenerator, and reference numeral 4 is a separator. is there. One of the processing tanks 1 and 2 is a tank into which the microorganism-supporting particles having an apparent specific gravity of about 1 to 1.3 are added while being impregnated with water. The other treatment tank 2 is a tank into which microorganism-supporting particles having an apparent specific gravity of about 1 to 0.7 are added while being impregnated with water. The treatment tanks 1 and 2 can have the same structure, but generally have different structures.

The above-mentioned regeneration device 3 is for peeling the biofilm grown on the particle surface by colliding the microbial-supported particles with the plate or by agitating with a water ejector or mechanical stirring.
The separating device 4 is a device that separates particles by specific gravity. The reproducing device 3 and the separating device 4 may be provided independently or integrally.

Next, the water treatment method of the present invention carried out by the above treatment apparatus will be described.

First, the water treatment method of the present invention is about
Microorganism-supporting particles having an apparent specific gravity of 1.3 to 0.7 are used. The microorganism-supporting particles are first put into the separation device 4. The separator 4 contains water having a specific gravity of about 1, and the particles having a specific gravity of more than 1 are settled and the particles having a smaller specific gravity float and are separated from each other. Then, the settled particles are extracted from the lower part of the separating device 4 and sent to the processing tank 1, and the floating particles are extracted from the upper part and sent to the processing tank 2. The particles sent to the tanks 1 and 2 are each subjected to the intended treatment (water treatment step). Here, the apparent specific gravity 1 does not need to be strictly controlled, and particles having a specific gravity within a certain range may be put into any of the processing tanks 1 and 2.

Particles treated in each treatment tank 1 and 2 have a specific gravity due to the biofilm that has grown on the surface (specific gravity of about 1.05) and the generated gases such as CO ₂ and N ₂ that are taken into the biofilm. Gradually becomes different from the initial one. Particles whose specific gravity has changed and are difficult to flow and suspend in the tanks 1 and 2 float to the upper part of the tanks 1 and 2 or settle to the lower part. The microorganism-supporting particles thus floated / settled are withdrawn intermittently or continuously from the tanks 1 and 2 and sent to the regenerator 3.

In the regenerator 3, the microorganism-supporting particles are collided with the plate or agitated by a water ejector or mechanical stirring to apply a shearing force to peel off the enlarged biofilm and regenerate the particles (regeneration step).

The microorganism-supported particles thus regenerated are separated again by the separation device 4
The specific gravity is then separated and returned to either of the above two types of processing tanks 1 and 2 (separation returning step). In addition, the biofilm that has been peeled off during regeneration is extracted as excess sludge from the regeneration device 3 or the like and appropriately treated.

[Operation] According to such a water treatment method, even if water treatment is performed using a microorganism-supporting particle in which particles having a slightly larger specific gravity than particles having a slightly smaller specific gravity than water are mixed, each particle is always It is introduced into the treatment tanks 1 and 2 under operating conditions where it is easily fluidized and suspended, and is used for treatment.

Therefore, according to the water treatment method of the present invention, since particles having a uniform tendency are supplied to the respective treatment tanks 1 and 2, the particles supplied to the respective tanks 1 and 2 and the water to be treated are sufficiently suspended. The operating conditions to be obtained can be easily determined.

The water treatment method of the present invention can be carried out by either an aerobic treatment method or an anaerobic treatment method. In that case,
It is also possible to perform anaerobic treatment in one treatment tank and aerobic treatment in the other treatment tank.

Further, according to the water treatment method of the present invention, it is needless to say that aerobic or anaerobic removal of organic components of waste water, nitrification, denitrification, etc. can be performed.

Furthermore, the water treatment method of the present invention is not limited to the above-mentioned embodiment, and for example, the withdrawal of the microorganism-supporting particles from each tank may be performed at a fixed amount on a regular basis.

"Effects of the Invention" As described above, the water treatment method of the present invention uses a microorganism-supporting particle having a weight substantially similar to that of water, and a treatment tank for introducing a microorganism-supporting particle having a specific gravity larger than water,
A treatment tank for introducing microbe-supported particles having a specific gravity smaller than that of water is provided for water treatment, and the particles used in these treatment tanks whose specific gravity has changed and cannot flow are drawn out from each tank, and the extracted microbe-supported The biofilm grown by applying shearing force to the particles is peeled off and regenerated, and the regenerated microorganism-supporting particles are separated by specific gravity and returned to either of the above two types of treatment tanks, so the microorganisms can be consumed with less energy. Can be fluidly suspended. Therefore, according to this water treatment method, it is possible to economically perform the water treatment, and it is possible to fluidize and suspend a large amount of the microorganism-supporting particles, so that the wastewater treatment rate can be increased per unit volume of the wastewater treatment apparatus. It can be miniaturized.

Further, in the water treatment method of the present invention, since particles having a well-balanced tendency are supplied to each treatment tank, it is possible to easily determine the operating conditions for sufficiently suspending the water to be treated and the microorganism-supporting particles, and thus the treatment apparatus. Driving becomes easier.

Further, according to the water treatment method of the present invention, it is possible to use the microorganism-supporting particles in which apparent specific gravity (apparent specific gravity in a state of being impregnated with water) of about 1 is mixed in the water treatment. When manufacturing the supported particles, it is not necessary to strictly control the specific gravity thereof, and the yield of production of the microorganism-supported particles can be improved.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a treatment apparatus suitable for carrying out an example of the water treatment method of the present invention, and FIG. 2 is a sectional view showing an example of a treatment apparatus used in a conventional water treatment method. is there. 1, 2 ... Treatment tank, 3 ... Regeneration device, 4 ... Separation device.

Claims (1)

[Claims] 1. A water treatment method in which microorganism-supporting particles supporting microorganisms are put into a treatment tank, and the suspension is flow-suspended together with water to be treated to treat an aqueous solution. Two kinds of treatment tanks are provided, and one of the treatment tanks is provided. Microorganism-supporting particles having an apparent specific gravity of about 1 to 1.3 are charged in a treatment tank impregnated with water, and about 0.7 to about 0.7 in a state where the other treatment tank is impregnated with water.
A water treatment process in which microbial-supported particles having an apparent specific gravity of 1 are introduced to treat the water to be treated, and the microbial-supported particles are extracted from these treatment tanks, and the extracted microbial-supported particles are subjected to a shearing force to be enlarged. A water treatment method comprising a regeneration step of regenerating particles by peeling off a biofilm and a separation step of separating the regenerated microorganism-supported particles by specific gravity and returning them to the treatment tank.