不同电子供体的硫自养反硝化脱氮实验研究

Study on Sulfur-based Autotrophic Denitrification with Different Electron Donors

采用硫自养反硝化处理模拟低浓度硝酸盐污染水.分别以单质硫、Na2S和Na2S2O3作为电子供体在3个反应器中连续运行进行脱氮实验,以考察不同电子供体条件下的脱氮效果.结果表明,在进水NO3--N浓度为13 mg.L-1的条件下,以Na2S2O3为电子供体脱氮效果最好,Na2S系统最差;Na2S2O3系统对低温的适应能力最强.20℃以上时,单质硫系统脱氮效率受传质效率和HRT的影响较大,HRT≥2 h时,系统对NO3--N和TN的平均去除率较高,分别为81%和79%,而HRT<2 h时,NO3--N和TN去除率分别降为47%和51%,出水NO2--N无明显积累,平均为0.53 mg.L-1;Na2S系统HRT保持在4 h时,NO3--N和TN的平均去除率分别为47%和41%,出水NO2--N平均质量浓度为0.29 mg.L-1;而Na2S2O3系统的NO3--N和TN平均去除率分别为99%和90%,出水NO2--N平均质量浓度为0.080 mg.L-1,且最短HRT可缩短至0.5 h.分子生物学分析表明,3个系统中存在不同的优势硫自养反硝化菌,单质硫系统中存在脱氮硫杆菌,而Na2S和Na2S2O3系统中得到的反硝化菌基因片段在基因库中尚未找到相似性高的菌种,可能是尚未登记的硫自养反硝化菌新菌种.

Sulphur-based autotrophic denitrification was applied to treat the low concentration nitrate-contaminated water.Different electron donors,namely,elemental sulfur,sulfide and thiosulfate,were used in three continuous reactors to compare the denitrification performance.When treating the low concentration nitrate-contaminated water（13 mg·L^-1）,the thiosulfate system showed the best performance and the sulfide system was the worst.The thiosulfate system was less sensitive to low temperature than the other two.At temperatures higher than 20℃,the sulfur system was greatly influenced by mass transfer efficiency and HRT.It removed 81% of nitrate and 79% of TN when HRT was no less than 2 h,but could only achieve a low nitrate and TN removal rate of 47% and 51% when HRT was shorter than 2 h.No obvious nitrite accumulation was observed and the average effluent nitrite was 0.53 mg·L^-1.The sulfide system could only remove 47% of nitrate and 41% of TN with 0.29 mg·L^-1 nitrite in the effluent at the HRT of 4 h.Meanwhile,the thiosulfate system had a high removal rate of 99% for nitrate and 90% for TN,with a low content of effluent nitrite of 0.080 mg·L^-1,and the HRT could be shortened to 0.5 h.The molecular biological analysis showed that different bacteria predominated in the three reactors,and that Thiobacillus denitrificans existed abundantly in the sulfur system,while the functional bacteria in the sulfide and thiosulfate systems could not be identified yet.A new species of sulfur-based autotrophic denitrification bacterium may have been found.