Performance of a haloalkaliphilic bioreactor under different NO3-/SO42- ratios

Abstract Effects of NO 3 - / SO 4 2 - ratio on denitrification and sulfate removal efficiency were investigated in model experiments applying haloalkaliphilic bioreactor. The reduction of both substrates performed well at different NO 3 - / SO 4 2 - ratios ranging from 17.6 to l.5. The removal rates of nitrate and sulfate were 6 and 1.39 kg m −3  d −1 , respectively, at NO 3 - / SO 4 2 - ratio 3.0, while sulfide concentration reached up to 703 g m −3 . The major sulfate-reducing and denitrifying bacteria were Desulfonatronovibrio sp. and Halomonas campisalis , respectively. Decrease in NO 3 - / SO 4 2 - ratio led to obvious changes in bacterial community. Although the sulfate reducers became dominant, the population of denitrifying ones also increased as it was demonstrated by analysis of PCR-amplified 16S rDNA fragments, which suggested that SRB and DB coexisted well in bioreactor.