Why do sewage and wastewater need nitrogen and phosphorus removal? The principle of nitrogen and phosphorus removal from sewage and wastewater is expounded.

Nitrogen and phosphorus are nutrient elements. After a large amount of nitrogen and phosphorus in industrial wastewater and domestic sewage enter the water body, aquatic organisms, especially algae, will multiply in large numbers, and a large number of dead aquatic organisms will be decomposed by microorganisms, consuming a lot of dissolved oxygen in the decomposition process, and the dissolved oxygen concentration in the water will drop sharply, thus affecting the survival of aquatic organisms such as fish. The principle of nitrogen and phosphorus removal by activated sludge process in municipal sewage plant is as follows: organic nitrogen is decomposed by microorganisms, then converted into nitrate, and then denitrified into nitrogen to be removed; Phosphorus removal is to use phosphorus accumulating bacteria to absorb more phosphorus after releasing phosphorus, so that phosphorus can be enriched in sludge, and phosphorus can be removed by discharging excess sludge.