What are the methods to remove ammonia nitrogen from sewage?

Biological method mechanism-biological nitrification and denitrification mechanism: in the process of biological denitrification of sewage, firstly, under aerobic conditions, through the role of aerobic nitrifying bacteria.

Ammonia nitrogen in sewage is oxidized to nitrite or nitrate.

; Then under anoxic conditions, nitrite and nitrate are reduced to nitrogen by denitrifying bacteria (denitrifying bacteria) and escape from sewage. Therefore, biological denitrification of sewage includes two stages: nitrification and denitrification. See figure 1 for the process flow of biological denitrification.

Nitrification is the process of transforming ammonia nitrogen into nitrate.

Comprises two basic reaction steps.

：

The reaction of nitrite bacteria to transform ammonia nitrogen into nitrite; The reaction of nitrifying bacteria to convert nitrite into nitrate.

Under anoxic conditions, facultative denitrifying bacteria (denitrifying bacteria)

The process of reducing nitrate or nitrite produced during nitrification to N2 is called denitrification. The electron donors in denitrification process are various organic substrates (carbon sources).

Biological nitrogen removal method can remove a variety of nitrogen-containing compounds, the total nitrogen removal rate can reach 70%-95%, and the secondary pollution is small and economical, so it is widely used at home and abroad. But the disadvantage is that it occupies a large area and has low efficiency at low temperature.