Effect of S/N ratio on operation characteristics and microbial community of double short-cut sulfur autotrophic denitrification system

Exploring the effects of different S/N ratios on the simultaneous accumulation of S0 and NO2−-N in the autotrophic denitrification process is of great significance for the enhanced Anammox denitrification and S0 resource recovery. The results showed that the low S/N ratio avoided the S2− accumulated toxicity, and the reactor could be quickly started within 9 days. When S/N ratio was 1, the highest S0 accumulation efficiency (S0AE) and NO2−-N accumulation efficiency (NiAE) could be obtained synchronously, which were 77.41 % and 87.83 %, respectively. The production of S0 and NO2−-N was up to 0.57 kg/(m3·d) and 0.18 kg/(m3·d), respectively. Too high or low S/N ratio would affect the S0AE and NiAE, respectively. With the increasing S/N ratio, sqr and narG genes expressions were enhanced and soxB and nirK genes expressions were weakened. Thiobacillus, Azoarcus and Pseudaminobacter were the dominant genera performing denitrification and desulphurization in double short-cut sulfur autotrophic denitrification.