The buried sewage treatment system is a modular, high-efficiency biological sewage treatment system. It utilizes biofilms as the primary purification process. It leverages the high biomass density, strong pollution tolerance, low power consumption, stable operation, and easy maintenance of biofilm reactors such as anaerobic biofilters and contact oxidation beds. This makes the system promising broad application prospects and widespread adoption.

Working principle of underground sewage treatment equipment

Introduction to anaerobic biological filter

1. Working principle of anaerobic biological filter

(1) Filtration: The filler intercepts and filters large particles and suspended solids in the incoming water;

(2) Hydrolysis: Anaerobic microorganisms can hydrolyze large molecular insoluble substances into small molecular soluble substances;

(3) Absorption: Anaerobic microorganisms adsorb and absorb organic pollutants in the water, part of which is used for their own growth and reproduction, and part of which is discharged through the U-shaped water seal in the form of biogas;

(4) Denitrification: The effluent from the contact oxidation bed is returned to the anaerobic filter. The denitrifying bacteria in the anaerobic microorganisms can utilize the nitrate nitrogen in the return water and convert it into nitrogen gas to remove nitrogen substances in the sewage.

After the rural sewage is treated in the anaerobic filter, the concentration of suspended solids, organic pollutants and nitrogen is reduced, and the load of the subsequent contact oxidation bed is also reduced.

2. Working principle of contact oxidation bed

(1) Adsorption: During the growth and reproduction process on the filler, aerobic microorganisms form a biofilm with a large surface area and high concentration, which can absorb most of the organic pollutants in the water in large quantities, thereby reducing the concentration of pollutants;

(2) Uptake and decomposition: When air is continuously supplied to the reactor, aerobic microorganisms can take the adsorbed organic pollutants as nutrients and metabolize them. A part of them is used for their own growth and reproduction, and a part of them is converted into carbon dioxide and water.

The contact oxidation bed further reduces the concentration of organic pollutants in rural sewage, and the removal rate of CODcr and BOD5 in the effluent reaches more than 80%, which can meet the national secondary sewage discharge standard.

3. Working principle of sedimentation tank

(1) The suspended sludge with a higher specific gravity than water in the effluent of the contact oxidation bed is caused to sink to the bottom of the tank by gravity, thereby removing it from the water and ensuring good effluent water quality;

(2) The sludge that settles to the bottom automatically returns to the contact oxidation bed to maintain the sludge concentration in the contact oxidation bed. (4. Disinfection Tank: Using solid chlorine to disinfect the effluent effectively kills pathogenic microorganisms such as bacteria, E. coli, and viruses. The treated water is clear, odorless, and has both bacterial and E. coli counts that meet national wastewater discharge standards.

Advantages of Underground Sewage Treatment Equipment:

There are various underground sewage treatment processes. Assuming the effluent meets standards, the most prominent advantages are:

1. The equipment is buried below the surface, allowing for greenery above, creating a beautiful environment.

2. The entire system generally requires no dedicated personnel for management.

3. It reduces floor space, allowing for parking above the equipment, eliminating the need for a factory building or other facilities.

4. It has no impact on the surrounding environment, generates minimal sludge, and produces noise levels below the standards for Class II areas.

5. It is easy to operate, utilizes innovative technology, delivers excellent results, and has a long service life.

6. The equipment can be arranged according to standard requirements or customized to suit the terrain.

Disadvantages:

1. It is difficult to maintain. Equipment failures are difficult to inspect and replace, which is often a major concern for owners. 2. Strong environmental adaptability, providing winter frost protection and summer flood control. Deeper burial depth and insulation are required in northern China.

Under what conditions are suitable for underground sewage treatment equipment?

Underground sewage treatment systems are generally recommended for small water volumes, low pollutant concentrations, simple composition, limited space, and considerations for environmental aesthetics.