Nitrogenous Constituents:

The principal nitrogenous compounds in domestic sewage are proteins, amines, amino acids and urea. Nitrogen may be present in different forms such as (i) organic nitrogen, (ii) albiminoid nitrogen, (iii) ammonia nitrogen, (iv) nitrite nitrogen, (v) nitrate nitrogen, depending on the condition of sewage. The determination of various forms of nitrogen helps in the selection of proper biological treatment units.