Denitrification performance and microbial diversity in a packed-bed bioreactor using biodegradable polymer as carbon source and biofilm support

摘要

A novel kind of biodegradable polymer, i.e., starch/polycaprolactone (SPCL) was prepared and used as carbon source and biofilm support for biological denitrification in a packed-bed bioreactor. The denitrification performances and microbial diversity of biofilm under different operating conditions were investigated. The results showed that the average denitrification rate was 0.64±0.06kgN/(m~3 d), and NH_3-N formation (below 1 mg/L) was observed during denitrification. The nitrate removal efficiency at 15℃was only 55.06% of that at 25℃An initial excess release of DOC could be caused by rapid biodegra-dation of starch in the surfaces of SPCL granules, then it decreased to 10.08 mg/L The vast majority of species on SPCL biofilm sample (99.71%) belonged to six major phyla: Proteobacteria, Bacteroidetes, Chloroflexi, Firmicutes, Spirochaetes and Actinobacteria. Proteobacteria were the most abundant phylum (85.50%) and mainly consisted of P-proteobacteria (82.39%). Diaphorobacter and Acidovorax constituted 52.75% of the identified genera which were denitrifying bacteria.