Correlation of reactor performance and bacterial community composition during the removal of trimethylamine in three-stage biofilters

Two three-stage biofilters packed with compost (BFC) or sludge (BFS), respectively, were prepared for removing trimethylamine (TMA) from waste gases. The correlation between reactor performance and bacterial community composition was investigated. Although TMA could be successfully removed by both biofilters, TMA removal efficiency in the bottom stage of the BFC was considerably higher than that of the BFS. Moreover, NH3 generated by the degradation of TMA could be removed in the BFC, while it accumulated in the BFS. Spatial and temporal shifts of bacterial community composition in both biofilters developed differently as assessed by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) followed by clone library analysis. Results showed that the lack of ammonia-oxidizing bacteria (AOB) may have contributed to the accumulation of NH3 in the BFS. Therefore, AOB may play a decisive role in a complete degradation of TMA. It is necessary for the sludge packing material to be inoculated with AOB in order to initiate ammonia oxidation in the bioreactor. Understanding of microbial community compositions in biofilters plays an important role in seeking biological limiting factors related to the removal efficiencies of TMA and other compounds from waste gas and further enhancing the performance of biofilters.