Characteristics of nitrogenous substrate conversion by anammox enrichment

The characteristics of nitrogenous substrates conversion by anammox enrichment were investigated using batch experiments. The anammox enrichment was proved able to convert hydroxylamine to hydrazine, as well as convert hydrazine to ammonia anaerobically, with the average conversion rates of 0.207 and 0.031 mmol gVSS−1 h−1. It could convert hydroxylamine and nitrite simultaneously, with ammonia as an intermediate product. The maximum conversion rates of hydroxylamine and nitrite were 0.535 and 0.145 mmol gVSS−1 h−1, respectively. Their conversion rates were enhanced by 26.7% and 120.7%, respectively, by raising the ratio of hydroxylamine to nitrite from 1:1 to 2:1. The characteristics of nitrogenous substrate conversion by anammox enrichment could be explained using the speculative anammox pathway based on van de Graaf model.