JPS5820680B2 - Fluidized bed sewage treatment equipment - Google Patents

Description

Detailed Description of the Invention This invention injects oxygen-containing gas into an upward flow path, a downward flow path, and an upward flow path in an aeration tank, and allows the liquid in the tank to rise without aeration. It has an air supply device that causes the air to flow upward into the counterflow path, warms it to the downward flow path, and circulates it from the lower end of the downward flow path to the upward flow path,
The present invention relates to a fluidized bed sewage treatment device that treats organic wastewater under aerobic conditions using microorganisms attached to carrier particles present in the liquid.

The above type of device was filed in Japanese Patent Application No. 51-1198 by the applicant of this patent.
No. 83 (see Japanese Unexamined Patent Publication No. 53-46156), No. 51
This has already been proposed in No. 154222 (see Japanese Patent Laid-Open No. 53-87567).

In this type of device, the raw water to be treated and the carrier particles to which microbial membranes are attached flow upward in the upward flow path by the airlift effect of the gas, and at this time the gas is subdivided by the carrier particles to form raw water, carrier particles, and The three phases of gas repeatedly make rapid contact, maintaining extremely high contact efficiency, and controlling the amount of liquid circulation.
Consequently, it is necessary to keep the contact treatment time optimal.

Generally, when designing equipment, the capacity of the aeration tank is determined based on the amount of wastewater to be treated, and the cross-sectional area of the upward flow path is Determine the cross-sectional area of the draft that will create the flow path.

However, in this case, if the aeration tank capacity is large, the cross-sectional area of the draft will also increase accordingly.

Even if an air supply source whose gas injection amount is commensurate with the large cross-sectional area of the draft is used, it becomes difficult to uniformly blow gas into the upward flow path. Effective contact of phases and control of circulation volume cannot be achieved.

Therefore, in the present invention, the cross-sectional area of the draft is determined according to the amount of gas blown into the air supply device, and when the capacity of the aeration tank is large and one draft with this cross-sectional area is insufficient, the total cross-sectional area Use the required number of drafts so that they are at a predetermined ratio to the capacity of the aeration tank, and install them in a roughly uniform arrangement within the tank, so that even if the aeration tank is large, the total cross-sectional area of the drafts is By maintaining the required ratio to the capacity, the three-phase contact efficiency is maintained high, and the circulation amount is appropriately controlled to enable effective treatment.

In addition, in this Kajimei, a part of the liquid that overflows into the downward flow path from the upper end of each draft and flows downward is taken out upward to the treated water outlet, thereby producing high-quality water that does not contain carrier particles. The purpose is also to obtain treated water.

The present invention will be described below with reference to the illustrated embodiments. 1 is a large-capacity aeration tank, 2 is an upward flow path installed in the tank with a draft 3, and 4 is oxygen in the upward flow path 2. Similarly, reference numeral 5 indicates a liquid supply device that supplies raw water into the upward flow path 2.

Specific gravity 1.1~2.6, particle size 0.3~LOmrn in the tank
degree sand, activated carbon, anthracite, plastic grains,
There are carrier particles made of a material on which the microorganisms can adhere, and these are mixed with activated sludge to form a microbial coating on the surface.

The apparatus is operated by supplying oxygen-containing gas and raw water to the upward flow path 2 using an air supply device 4 and a liquid supply device 5.

The amount of carrier particles is 50% or less of the capacity of the aeration tank, preferably about 15 to 30%, and the BOD area load per total surface area of carrier particles is 10? B OD/m, day or less.

In addition, the relationship between the cross-sectional area of the draft 2 and the air supply device 4 is that the blowing speed of the gas blown into the upward flow path is the terminal velocity of the carrier particles (
falling velocity), the particles are fluidized in the upward flow path, and the liquid that has flowed upward in the upward flow path flows downward in the downward flow path 6 surrounding the upward flow path. It is designed to circulate once in approximately 1 to 5 minutes from the lower end of the flow path into the upward flow path.

In the device shown in Fig. 12, the aeration tank has a rectangular planar shape;
Four drafts 3 are arranged at regular intervals in the long side direction in the center of the tank, and the total cross-sectional area of the upward flow path 2 due to these four drafts 3 is approximately a predetermined ratio to the capacity of the tank 1. do something.

Therefore, when the apparatus is operated as described above, raw water and carrier particles rapidly flow upward in the upward flow path 2 provided by each draft 3 due to the air lift action of the gas, resulting in a three-phase flow of raw water, particles, and gas. conducts a suitable treatment process with high contact efficiency.

The raw water and carrier particles overflowing from each upward flow path to the downward flow path 6 also come into contact in a parallel flow state when flowing downward through the flow path 6,
The raw water is purified by adsorption and oxidation, and thus enters the nearby upward flow path from the lower end of the downward flow path and circulates.

Then, the sufficiently purified liquid flowing downward in the downward flow path rushes into the downward flow path from above and passes through the upper part of the inside of the downward flow path to the overflow part 7 and the take-out part 8. The water is turned back under the split wall 9, and the take-out portion 8 is directed upward to exit the treated water take-out port 10.

Therefore, the problems that arise when processing is carried out by providing a draft with a commensurately large cross-sectional area in a large-capacity aeration tank are completely eliminated.

As shown in Fig. 3, the aeration tank 1 consists of two partial end tanks 1a and 1a, each with an end wall 1' having a capacity matched to one draft 3, and one without an end wall if necessary. Alternatively, it may be assembled by arranging and connecting a plurality of partial intermediate tanks 1b, and may be constructed in a prefabricated manner by arranging one draft in each partial tank 1a1b.

The embodiment shown in FIG. 45 shows a case where the present invention is applied to a large capacity cylindrical aeration tank 1.

In this case, a plurality (four in this case) of cylindrical drafts 3 are provided inside a cylindrical split tube 11 that protrudes concentrically into the tank from above to form an upward flow path 2.

Of course, the draft may be a rectangular tube similar to the previous embodiment.

The total cross-sectional area of these four drafts is the required proportion to the capacity of the large cylindrical aeration tank.

In this example, as in the previous example, the three phases of raw water, carrier particles, and gas are effectively in contact with each other in each upward flow path, and the liquid overflowing from the upper flow path to the downward flow path and the carrier The particles come into contact with each other in parallel flow as they flow downward through the downward flow path, and while the liquid is treated and circulated through the upward flow path, a portion of the purified liquid flows outside the split tube 11. The treated water outlet 1
It comes out as 0.

In addition, the same components as in the above-mentioned embodiment are designated by the same reference numerals.
The explanation will be omitted.

As is clear from the above, according to the present invention, even a large-sized apparatus with extremely high processing efficiency and excellent performance can be easily provided.

□ Also, the liquid and carrier particles overflowing from the upper end of each draft into the downward flow path are blocked by the split wall or split tube and cannot reach the treated water outlet.

Therefore, only the liquid that flows downward through the downward channel, passes through the split wall or the bottom end of the split tube, and turns toward the ground is obtained at the outlet as treated water, so there is no carrier particles mixed into the treated water. , the water quality is extremely good.

[Brief explanation of drawings]

Fig. 1 is a plan view of an embodiment of the apparatus according to the present invention, Fig. 2 is a longitudinal side view of the same, and Fig. 3 is a pre-configured aeration tank of the apparatus shown in Figs. 1 and 2. FIG. 4 is a plan view showing still another embodiment of the present invention; FIG. 5 is a longitudinal side view of the same; in the figure, 1 is an aeration tank; 2 is an upward flow 3 is a draft that forms an upward flow path in the tank, 4 is an air supply device, and 6 is a downward flow path.

Claims (1)

[Claims] 1. In a fluidized bed sewage treatment device in which biological carrier particles are present in the aeration tank and organic wastewater is treated under aerobic conditions by microorganisms attached to the particles, the upper end of the aeration tank is almost near the water surface, and a plurality of upward passages formed inside each draft by a plurality of drafts whose lower ends are spaced apart from the tank bottom, and a downward passage formed between each outside of the draft and the inside of the aeration tank; An air supply device that blows gas containing oxygen into each of the upward flow paths, a treated water outlet provided at the upper part of the aeration tank wall, and an upper end above the water surface and a lower end below the treated water outlet. The liquid and carrier particles flowing upward through each upward flow path inside the downward flow path and the carrier particles are located at the bottom and enter the downward flow path, and are provided opposite to the treated water outlet. It has an overflow part that is heated to flow downward through the counterflow path, and a partition wall that partitions the liquid flowing downward through the overflow part into a take-out part where the liquid flows upward toward the treated water take-out port. , gas is blown into the upward flow path from the air supply device for aeration, and then the liquid in the tank is made to flow upward during the upward flow to heat the downward flow path. A fluidized bed type sewage treatment device characterized in that the liquid is circulated in a counter-flow path and a part of the liquid in the downward flow path is taken out from a treated water outlet.