Effects of organic carbon source on the performance and bacterial structure in biofilm processes for source water pretreatment

Abstract

The operation performance of biofilm system is limited by the oligotrophic quality of source water, especially the bioavailable organics. In this study, two lab-scale biofilm reactors (R1 and R2) feeding different organic carbon sources (OCS) were built up using sediment in drinking water source as bacterial source. Experimental results showed that sediment in biofilm systems enhanced the NH4 +-N removal performance. Using ethanol as OCS was more beneficial to the removal of NH4 +-N with ammonia removal efficiency (ARE) of 87.0 ± 5.4%, which was higher and more stable than that of glucose with ARE of 83.9 ± 13.3%. Organic carbon source changed the bacterial structure in biofilm systems. The dominant phyla in biofilm under ethanol condition were Proteobacteria, Bacteroidetes and Firmicutes with relative abundances (RA) of 29.1%, 32.7% and 22.0%, respectively. The dominant phyla in biofilm exposure to glucose was Proteobacteria with an RA of 63.4%. At genus level, Nitrospira, Lachnospiraceae, Arcobacter and Hyphomicrobium were dominant under ethanol condition (R1) with the total relative abundance of 20.5%. Sphaerotilus was the dominant genus under glucose condition (R2) with RA of 33.72%. These dominant bacteria were basically having the ability for the removal of nitrogen and organic matter.