Research on partial nitritation for domestic sewage by biological aerated filter

Abstract:

To study the feasibility of partial nitritation of domestic sewage with low ammonia nitrogen, actual domestic sewage was treated by high rate bio-filter and up-flow biological aerated filter(UBAF). The effect of flow direction on the performance of high rate bio-filter removing COD and NH₄+-N and the effect of temperature and DO on the efficiency of UBAF for partial nitritation were researched. Results showed that at the hydraulic loading of 0.58 m³／(m²·h), COD volume loading of 2.30 kg／(m³·d), air-water ratio of 3.6∶1 and room temperature, up-flow filtration achieved high COD and low ammonia-nitrogen removals. Ammonia nitrogen removal rate reached 84.58％ and nitrite content in the effluent of UBAF achieved 23.01 mg／L on the conditions of temperature 30-33 ℃, DO 2.5-3.0 mg／L and pH value 7.8-8.1. Further study on the change of nitrogenous compounds in different depth combining with FISH demonstrates that a certain degree CANON process could exist at the end of UBAF. The two-stage reactor could domesticate decarbonizing and denitrifying bacterias independently, the partial nitritation of domestic sewage with low ammonia nitrogen can be achieved.