Study on Sulfur-Based Autotrophic Denitrification by Immobilized Pellets
包埋固定化微生物的硫自养反硝化实验研究

Autotrophic denitrification by immobilized microorganisms was investigated in this study. Using thiosulfate as the electron donor, the lab scale up-flow sludge blanket reactor ran continuously for 220 days under the room temperature to investigate the effects of cultivate conditions, influence factors and optimal operating parameters. It took 23 days to finish the initial domestication stage. A nearly complete removal of nitrate (100 mg/L) was attained at nitrate loading rates (NLR) of 0.22 kg/(m3·d). The results revealed that the denitrification efficiency was dependent on temperature, influent nitrate concentration and hydraulic retention time (HRT), and temperature was the most important factor. In spring and autumn, nitrate and total nitrogen removal efficiency remained 90%-100% at the NLR of 0.96 kg/(m3·d). The shortest HRT and the highest denitrification rate could achieved 1h and 39.8 mg/(L·h) separately. While in winter the shortest HRT was 2 h and no nitrite or sulfide accumulation was detected. Molecular biological analysis indicated that denitrifying bacteria were re-enriched successfully in the immobilized pellets.