1. The principle of action of anaerobic biological filter
1) Filtration: the filler intercepts and filters large particles and suspended solids in the inlet water;
2) Hydrolysis: anaerobic microorganisms can hydrolyze insoluble substances of macromolecules into soluble substances of small molecules;
3) Absorption: anaerobic microorganisms adsorb and absorb organic pollutants in water, part of which is used for their own growth and reproduction, and part of which is sealed out through U-shaped water in the form of biogas;
4) Denitrification: The effluent from the contact oxidation bed is returned to the anaerobic filter, and the denitrifying bacteria in the anaerobic microorganisms can use the nitrate nitrogen in the reflux water and convert it into nitrogen to remove the nitrogen in the sewage. After the treatment of rural sewage by anaerobic filter, the concentration of suspended solids, organic pollutants and nitrogen is reduced, and the subsequent load of contact oxidation bed is also reduced.
2. The principle of action of the contact oxidation bed
1) Adsorption: aerobic microorganisms form biofilms with large surface area and high concentration during the growth and reproduction process of the filler, which can adsorb most of the organic pollutants in the water in large quantities and reduce the pollutant concentration;
2) Ingestion and decomposition: In the case of continuous air flow to the reactor, aerobic microorganisms can take the adsorbed organic pollutants into the body as nutrients and metabolize them, part of which is used for their own growth and reproduction, and part of which is converted into carbon dioxide and water. The exposure to hydrogenated bed further reduces the concentration of organic pollutants in rural sewage, and the removal rate of CODcr and BOD5 in effluent reaches more than 80%, which can meet the national secondary standard for sewage discharge.