Nitrogen balance and transformation in the nitrification process of coking wastewater and the influence on nitrification kinetics

This paper describes the total nitrogen balance, and the direction and degree of nitrogen transformation during the nitrification process of coking wastewater. According to the actual nitrification process, the conventional nitrification kinetic equation was amended. After 48 h of nitrification, the total nitrogen content remained almost the same with error less than 0.6%. The total removal efficiency of NH₄⁺-N was 91.1%, in which blow-off, producing cells and transforming to nitrate nitrogen accounted for 1.1, 17.8 and 72.2% respectively. Considering the influences of NH₄⁺-N blow-off and conversion from cyanide, thiocyanide and organic nitrogen, the nitrification kinetic equation was amended as μ′=0.82·S/(0.48+S).