Effect of COD level and HRT on microbial community in a yeast-predominant activated sludge system

Abstract

This study was conducted to compare the effect of influent chemical oxygen demand (COD in) level and hydraulic retention time (HRT), two primary components of influent COD loading rate (COD LR), on the structure and function of sludge microbial community in a yeast-predominant activated sludge system (1 m H × 0.2 m D) for synthetic industrial wastewater. A combination of polymerase chain reaction-denaturing gradient gel electrophoresis with BIOLOG community-level physiological profiles was used. At higher COD LR and higher COD in and identical HRTs, more microbial species were supported and could metabolise a greater variety of carbon sources in the aerated column. Conversely, a shorter HRT at identical COD in supported fewer microbial species, which resulted in the metabolism of fewer carbon sources.