The role of anaerobic tank is to improve the phosphorus release efficiency of phosphorus accumulating bacteria in strict anaerobic environment, and cooperate with aerobic tank to remove phosphorus. The main function of anoxic tank is denitrification of nitrogen by denitrifying bacteria at low dissolved oxygen concentration, and denitrification provides partial alkalinity, which provides favorable conditions for subsequent nitrification in aerobic tank.
In the aerobic tank, microorganisms decompose and metabolize organic matter under aerobic conditions, and nitrifying bacteria attached to the fluidized packing carry out efficient nitrification reaction, which gradually converts organic nitrogen and ammonia nitrogen in sewage into nitrite and nitrate, and at the same time, phosphorus-accumulating bacteria absorb excessive phosphorus to form high-concentration phosphorus-containing sludge; After the mud and water in the sedimentation tank are separated, the supernatant is subjected to biochemical filtration through the soft fixed filler filtration zone to further remove nitrogen, phosphorus and other pollutants in the water.
So denitrification is to convert harmful pollutants into harmless gases, which can be safely discharged into the environment. This is the process of removing nitrogen from wastewater. Excessive concentration of nitrogen (and carbon) will lead to serious environmental problems, such as ecological imbalance, excessive growth of toxic algae in waterways, depletion of oxygen levels to destroy marine life, unpleasant smell and pollution of drinking water supply. Excessive nitrogen in drinking water will cause health risks to people and animals, especially infants, pregnant women and high-risk adults.