JPS5918119B2 - organic wastewater treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention was first filed in Japanese Patent Application No. 51-1198 by the applicant of this patent.
83 (see Japanese Patent Application Laid-Open No. 53-46156), organic wastewater is treated under aerobic conditions in a fluidized bed of biological carrier particles and the (primary) treated water is floated under pressure. The present invention relates to an organic wastewater treatment device that passes through a separation device to separate suspended solids (SS) such as surplus sludge suspended in the treated water by pressure flotation to obtain clear secondary treated water.

In the fluidized bed of the previous fluidized bed sewage treatment equipment described above, microorganisms adhere to the biological carrier particles and a certain amount of biological mass is stably retained without returning sludge (MLSS concentration 3000 to 6000 p). ), stable BOD removal is possible even if the BOD tank load is 4 to 6 times higher than in the conventional activated sludge method, and the resulting treated water can be directly discharged into a sewer system or the like.

However, the organic matter in the sewage that undergoes biodegradation within the equipment proliferates and grows as excess sludge on the surface of the carrier particles, and some of it separates from the particles and is mixed with the treated water and discharged, so the discharge regulation value is In cases where strict regulations apply, it is recommended to separate the water and release it.

Therefore, the present invention introduces this (primary) treated water to a pressurized flotation separation tank, and floats and separates the suspended matter in the treated water that has been flocculated with water treatment chemicals such as flocculants in the tank, resulting in clear (secondary) )
This was developed with a focus on the ability to obtain treated water, and as a result, it retains the features of the fluidized bed sewage treatment equipment of the prior art, while also making it possible to obtain even clearer treated water, as well as to eliminate excess sludge. The suspended solids such as these can be obtained in a concentrated state, so dehydration can be easily performed, and the area required for the entire equipment is significantly reduced compared to when a coagulation chamber is installed around the outer periphery of a fluidized bed sewage treatment equipment. It has characteristics.

The present invention will be explained below with reference to an illustrated embodiment. 4 A fluidized bed type sewage treatment apparatus which is a part of the organic wastewater treatment apparatus of the present invention has a vertically elongated upward flow channel provided in an aeration tank 10. 11 and
The liquid flowing upward in the upward flow path overflows and flows downward, and at the same time, the lower end of the upward flow path is connected to the lower end of the upward flow path, and the liquid flowing downward is circulated to the upward flow path. 12.

According to the illustrated embodiment, both flow channels 11, 12 have double inner and outer cylinder walls 11' arranged concentrically, or a rectangular cylinder wall 11';
12' forms an upward flow passage 11 at the center and a downward flow passage 12 outside thereof, and the lower end of the outer cylinder wall 12' is extended below the inner cylinder wall 11', and preferably the extension part is tapered. The liquid flowing downward through the downward flow path enters the lower end of the upward flow path, flows upward, and is circulated.

Then, a printing plate 13 is inserted into the downward flow path 12 from above, and the upper part of the inside thereof is passed into the introduction part 14 from the upward flow path and the treated water takeout part 15. A liquid supply device 16 that introduces wastewater to be treated, and an air supply device 17 that blows oxygen gas or air into an aeration tank at the bottom of the flow path, and the device contains sand, activated carbon, anthracite, Carrier particles made of plastic particles or other materials to which organic organisms can adhere are introduced and mixed with activated sludge to form a film of microorganisms.

Although the liquid supply device 16 is shown as supplying waste water to the upward flow path from above, it may be provided at the bottom of the upward flow path like the air supply device 17.

In the operation, gas containing waste water and oxygen is supplied to the lower part of the upward flow path 11 by devices 16 and 17, and the blown gas maintains the carrier particles to which microorganisms are attached in a fluid state, and thereby both flow paths This induces liquid circulation at 11 and 12.

The carrier particles have a specific gravity of 1.1 to 2.6 and a particle size of 0.3 to 1.0.
mm is appropriate, the amount of packed particles is 50% or less of the volume of the aeration tank, preferably about 15 to 30%, and the operation is performed under conditions where the BOD area load per total surface area of carrier particles is 109BOD/',a or less. .

In addition, the gas blowing speed is set to be higher than the terminal velocity (falling speed) of the carrier particles based on the cross-sectional area of the upward flow path, in order to fluidize the carrier particles and induce liquid circulation. The ratio of amounts is preferably in the range of 1:3 to 1:10, and the liquid is set so that it circulates once in 1 to 5 minutes.

As a result, in the upward flow path 11, the sewage and the carrier particles to which the microbial film is attached rapidly flow upward due to the air lift effect of the gas.
At this time, the gas is subdivided by carrier particles, and the three layers of sewage, carrier particles, and air repeatedly come into rapid contact with each other to carry out a suitable treatment process with extremely high contact efficiency.

In addition, when the carrier particles enter the downward flow path riding on the wastewater introduced from the upper end of the upward flow path into the downward flow path 12, they descend in a fluid state, and the sewage flows downward in the downward flow path. The wastewater is purified by adsorption and oxidation even in the downward flow path, and enters the upward flow path from the bottom end of the downward flow path and circulates, while some water is circulated. Take it out as treated water from the stream 15
flows out from.

The water flow linear velocity in each flow path is relatively high due to the air lift in the upward flow path and due to the downward flow in the downward flow path, both of which are high-speed flows of 30 to 50 m.

Therefore, in addition to appropriately determining the cross-sectional area of the upward flow path, the cross-sectional area of the downward flow path is determined appropriately relative to the upward flow path, and the liquid circulation time is determined as described above. Allow a long contact treatment time to ensure sufficient purification.

As mentioned above, organic matter in sewage that comes into contact with carrier particles in the upward flow path and downward flow path and undergoes biodegradation by microorganisms attached to the surface is deposited as excess sludge on the surface of the carrier particles. They multiply and grow as particles, and some of them are peeled off from the particles and removed from the extraction section 15.
It is mixed with the (primary) treated water flowing out from the water and discharged.

In other words, the take-out unit 15 removes the plate 1 that has entered the water from above the water surface.
3, it is cut off from the introduction section 14.

Therefore, the microbial carrier particles are not mixed with the water flow to the extraction section 15, and only the excess biofilm flocs separated from the particles are mixed with the water flow and discharged from the extraction section.

゛ Therefore, in the present invention, the treated water flowing out from the take-out part 15 is guided through a conduit shown as a system 18 through a stirring tank to a flotation separation tank equipped with a built-in inclined plate, and air bubbles generated from pressurized water are introduced into the flocs. By attaching the particles, they were floated and separated under pressure.

The primary treated water is first led to a stirring tank 19 equipped with stirring means.

This stirring tank is used to cause the suspended matter in the primary treatment water to grow into flocs by acting on the flocculant, and the water treatment agent is injected into the thread 18 by the concentrating means 19' and rapidly in the conduit of the system 1B. It is stirred to evenly disperse and mix in the liquid.

Therefore, in the stirring tank 19, the stirring means is rotated at a stirring speed that allows the flocs to grow gradually without being destroyed.

Alternatively, the drug injection means may be one that injects the drug into the stirring tank.

The treated water containing flocs and discharged from the stirring tank is then led to a pressurized flotation separation tank 20 having a built-in inclined plate.

The pressurized flotation separation tank 20 is a typical one having inclined chambers 21a and 21b which are vertically separated below the liquid surface by an inclined plate 21, and a treated water spouting nozzle 22 provided in the lower inclined chamber. Indicated.

A system 20' for injecting pressurized water is connected to the system 1B for introducing the treated water from the stirring tank to the above-mentioned jet nozzle 22, so that the pressurized water is injected.

Therefore, when the treated water is ejected together with pressurized water into the lower inclined chamber 21b of the pressurized flotation separation tank, the gas dissolved in the pressurized water is generated as bubbles and adheres to the flocs contained in the treated water, causing the inclined Both chambers 21a may or may not be transmitted along the lower surface of the plate 21.

The flocs are floated on the common liquid level of 21b.

Of course, the treated water also enters the upper inclined chamber 21a beyond the upper end of the inclined plate 21.

For this reason, both chambers 21a. Clear secondary treated water can be taken out from the bottom of the tank 21b, and the flocs that have floated to the surface of the tank can be discharged into a sludge pool using a skimmer or the like, and then extracted from there using a sludge pipe.

25 is a storage tank for secondary treated water, 23 is a sludge reservoir, 23' is a skimmer, and 24 is a sludge pipe.

Alternatively, pressurized water can also be supplied into a pressurized flotation tank.

In this way, in the present invention, the primary treated water obtained from the fluidized bed sewage treatment equipment is treated at high speed in a pressurized flotation separation tank, and suspended matter in the primary treated water is floated and separated as flocs, resulting in clear secondary treatment. For this reason, separation in a flocculation separation tank requires constant monitoring to control the flocculation state and the top surface level of flocs, but this method does not require such trouble and Mixing and stirring in a stirring tank can also be carried out roughly, and the operation is simple.

Moreover, the sludge to be discharged is also in a concentrated state, and subsequent dewatering can be easily performed.

[Brief explanation of drawings]

The drawing is a flow sheet of one embodiment of the present invention, and in the drawing, 10
1 is an aeration tank of a fluidized bed sewage treatment equipment, 11 is an upward flow path, 1
2 is a downward flow path, 15 is a treated water extraction section, 16 is a liquid supply device, 1T is an air supply device, 18 is a system for delivering primary treated water, 2
0 indicates a pressurized flotation separation tank.

Claims (1)

[Scope of Claims] 1. A fluidized bed sewage treatment device that treats organic wastewater under aerobic conditions by treating organic wastewater under aerobic conditions by making biological carrier particles exist in an aeration tank and mixing them with activated sludge. An upward flow path formed by a cylindrical wall whose upper end is almost near the water surface and whose lower end maintains a distance from the bottom, and a downward flow path formed by a cylindrical wall whose upper end is above the water surface and has a bottom at its lower end. An air supply device for blowing oxygen gas or air is provided at the bottom of the upward flow path, and the side plate plunges from above the water surface to below the water surface and faces the submerged part of the side plate in the downward flow path. A discharge port for treated water is provided at the location, and the wastewater flows upward through the upward flow path, then flows downward through the downward flow path, and part of it is entrained in the upward flow path again, while some of it is A fluidized bed type sewage treatment equipment in which treated water is taken out from an outlet and carrier particles with a microbial film attached to the surface are circulated in an upward flow path and a downward flow path. , a processed flotation tank with a built-in inclined plate, a system for guiding the (primary) treated water obtained from the fluidized bed sewage treatment equipment to the pressurized flotation tank, and an agitation system with a stirring means connected in the middle of this system. A tank, a bend that enters the stirring tank or a chemical injection means for injecting water treatment chemicals into the treated water in the tank, and a pressure flotation separation tank that mixes air bubbles into the treated water to float the flanks in the treated water. What is claimed is: 1. An organic wastewater treatment device comprising means for flocculating and pressurizing suspended matter in primary treated water from a fluidized bed sewage treatment device.