Performance and microbial community of aerobic dynamic membrane bioreactor enhanced by Cd(II)-accumulating bacterium in Cd(II)-containing wastewater treatment

Abstract

In this study, a strain of Cd(II)-accumulating bacterium, Pseudoalteromonas sp. SCSE709-6, was inoculated into aerobic dynamic membrane bioreactor (ADMBR) as bioaugmentation to treat Cd(II)-containing wastewater, whilst the microbial community in the activated sludge and biofilm were compared integrated with performance under the cadmium stress and bioaugmentation. Results indicated that the performance of ADMBR was greatly inhibited by cadmium stress gradient but was substantially improved by bioaugmentation which corresponds to the obvious changes of microbial community. In genus level, Thiothrix and Meganema were predominant bacteria under cadmium stress, while Flavobacterium and Lactococcus were enriched after bioaugmentation. In phylum level, Bacteroidetes demonstrated a higher resistance against Cd(II) than Proteobacteria with bioaugmentation. Moreover, Stenotrophomonas and Dechloromonas relating to total nitrogen (TN) removal were mainly detected in biofilm, indicating the significant role of dynamic membrane. The promising results presented in this feasibility study demonstrated the great potential of using Cd(II)-accumulating bacterium to enhance the performance of activated sludge in treating Cd(II)-containing wastewater.