Influence of Organic Loading on the Performance and Microbial Structure of the Airlift Combined Biofilm Reactor (ACBR)

A novel airlift combined biofilm reactor (ACBR) was developed and the influence of influent organic loading rate on the removal performance and microbial structure was studied. The experimental results indicated 80% nitrogen removal was achieved in the ACBR reactor under the influent organic loading of 0.28-0.53 kgCOD/(m³.d), when the organic loading was further increased, nitrification turned to the limiting step of nitrogen removal. Batch experiments and substrates distribution in the reactor indicated that the reactor was successfully stratified and nitrification and denitrification were mainly accomplished in the aerobic zone and anoxic zone. FISH experiments revealed that beta-subclass was one of the predominant group of bacteria within the biofilm community, Nitrosospira and Nitrospira were the main ammonia oxidizer and nitrite oxidizer respectively. The decreased nitrifier with the enhanced influent organic loading resulted in the deterioration of nitrification effect of the reactor.