Nitrogen compounds behavior in biological activated sludge process SNH can be used directly as a nutrient for bacteria growth, or nitrified into SNo by autotrophic bacteria; P SND must be firstly decomposed into SNH (Ammonification), then participates in the SNH material flow XND must be firstly hydrolyzed into SND, then participates in the snd material flow 05/10/2002Nitrogen compounds behavior in biological activated sludge process SNH can be used directly as a nutrient for bacteria growth, or nitrified into SNO by autotrophic bacteria; SND must be firstly decomposed into SNH (Ammonification), then participates in the SNH material flow; XND must be firstly hydrolyzed into SND, then participates in the SND material flow. 05/10/2002