Effects of hydraulic retention time on the performance and microbial community of an anaerobic baffled reactor-bioelectricity Fenton coupling reactor for treatment of traditional Chinese medicine wastewater

The aim of the present paper was to investigate the effects of hydraulic retention time (HRT) on the performance and microbial community dynamics of an anaerobic baffled reactor-bioelectricity Fenton (ABR-BEF) coupling reactor for treating traditional Chinese medicine (TCM) wastewater. The results show that the average removal of chemical oxygen demand (COD) and NH3-N at HRTs of 24 h and 18 h were high ( > 90% and > 70%, respectively), but decreased to about 40% and 30% when operating at 12 h HRT. For the electrical production performance, the maximum power density was 196.86 mW/m(3) at a HRT of 18 h. Methanomicrobia was the dominant archaea in the coupling reactor and the relative abundance of Methanothrix and Methanolinea increased with decreasing HRT. For the bacteria, the relative abundance of Planctomycetia significantly decreased with a short HRT; however, Anaerolineaceae was always the dominant bacterial taxa, which could guarantee efficient treatment of TCM wastewater.