MINERALIZATION OF ORGANIC NITROGEN IN ANAEROBICALLY DIGESTED SLUDGE
城市污泥有机氮矿化动态及其影响因素的研究

Mineralization of organic N is one of the principle factors affecting the annual amount of sewage sludge applied to crop land.The mineralization of organic nitrogen in anaerobically digested sludge from secondary sewage traetment plant was studied using a procedure of periodic leaching of soil sludge sand mixtures.31 to 65% of organic nitrogen in the sludge was mine ralized in the calcareous heavy loam soil amended with sludge at application rate from 3% to 24% during a incubation period of 14 weeks.Sludge exhibited a rapid, initial release of inorganic N, followed by a relatively constant rate of mineralization from weeks 6 to 14.The mineralization dynamics of organic N could be described by a classical first order kinetics: Nm= N0(1-e-Kt).Net mineralization rates of organic N increased as temperature increased or sludge addition decreased when sludge were added to soil at rates ranging from 0 to 6%, but the amount of N mineralization were similar (31%-38%) at application rates more than 6%.