A comparative study of an anaerobic-oxic (AO) system and a sequencing batch biofilm reactor (SBBR) in coating wastewater treatment and their microbial communities

Abstract

Abstract Coating wastewater from paper mills has been characterized by a high chemical oxygen demand (COD), high total suspended solids (TSS) and a high degree of color. In this paper, a sequencing batch biofilm reactor (SBBR) and an anaerobic-oxic (AO) system that consisted of a hydrolytic acidification reactor and an activated sludge reactor (HAASR) were implemented to treat coagulated coating wastewater from a paper mill. The COD, color and TSS removal efficiencies of the SBBR were 87.7 %, 33.5 %, and 41.4 %, and those of the HAASR were 85.3 %, 22.5 % and 19.4 %, respectively. It is proposed that more recalcitrant compounds were removed by the SBBR than by the HAASR. The microbial communities of the SBBR sludge and the HAASR sludge were evaluated and indicated that the SBBR sludge had lower microbial richness and diversity than the HAASR sludge. Moreover, Proteobacteria and Bacteroidetes were the dominant bacteria in both the HAASR and SBBR sludges.