Characteristics of nitrite and nitrate in situ denitrification in landfill bioreactors

The objective of this research was to investigate the macroscopical effect of high concentration nitrite and nitrate denitrification on waste decomposition and to evaluate the kinetics of NO 3 - –N and NO 2 - –N removal. Two reactors loaded fresh refuse were fed 4000 mg NO 3 - –N/L or 4000 NO 2 - –N/L every 48 h, respectively. Results showed that NO 3 - –N addition was more effective on promotion of the waste degradation process as compared to NO 2 - –N addition. In the initial stage, NO x - –N removal was mainly contributed by adsorption rather than denitrification. NO x - –N reduction rate data obtained from microcosm experiment were fit to Monod kinetics, with specific removal rates of 1.625 mg NO 3 - –N/(g dry waste d) and 1.125 mg NO 2 - –N/(g dry waste d) and nitrogen removal half-saturation constants of 1250.5 NO 3 - –N/L and 125.5 NO 2 - –N/L, respectively.