Abstract
Thiobacillus denitrificans is widely used in the autotrophic denitrification process to remove nitrate. The results from batch experiments indicated that the optimum cultivation for the growth and bioactivity of T. denitrificans could be obtained under anaerobic condition at 30℃. Besides the addition of ordinary basal mineral salts, the optimal culture medium should be composed of 40 ml of trace element solution, 15 g/l Na2S2O3·5H2O and 5.0 g/l KNO3. Under the optimum conditions, the average ratios of ΔS2O32–－S/ΔNO3–－N and ΔSO42–/ΔNO3–－N were 3.8 g/g and 10.9 g/g, respectively, which were comparable with the theoretical values of the autotrophic denitrification using thiosulfate as electron donor, and the SO42– generation, S2O32–－S consumption and NO3–－N denitrification rates were 306.0, 104.9 and 47.3 mg/l·d, respectively. After 12－day cultivation, about 80% of NO3–－N could be removed from the culture with 700 mg/l of initial NO3–－N contained.
