焦化废水活性污泥中降解硫氰化物细菌种群多样性分析

Biodiversity of Thiocyanate-degrading Bacteria in Activated Sludge from Coking Wastewater

硫氰化物(SCN-)是焦化废水中COD的主要来源之一,其在生物处理工艺好氧段的去除效果直接影响出水的达标排放,活性污泥中的微生物种群在SCN-生物处理中发挥重要作用.以SCN-为唯一碳源和能源驯化活性污泥,研究其对100、300和600 mg·L-1SCN-浓度的去除降解效果,并利用454测序技术解析污泥中降解SCN-的细菌多样性.结果表明,驯化污泥能有效去除100~600 mg·L-1SCN-,SCN-浓度越高,去除速率越高,然而细菌群落多样指数越低;原始污泥和驯化污泥的细菌门类群主要为Proteobacteria、Bacteroidetes、Chlorobi、Planctomycetes、Acidobacteria、Nitrospira、Firmicutes和Unclassified,其中Proteobacteria和Bacteroidetes门占主导地位;Thiobacillus是主要的SCN-降解菌,在3个污泥样品中的丰度分别为3.07%、8.63%和0.27%.Thiobacillus是浓度小于300 mg·L-1SCN-时焦化废水中主要的SCN-降解菌,而在600 mg·L^(-1) SCN-高浓度时低丰度的SCN-降解菌群可能发挥协同降解作用.这些结果为揭示焦化废水处理SCN-污染物的去除机制提供了基础.

Thiocyanate（ SCN-） is one of the main sources of COD in coking wastewater,and SCN-removal efficiency of the aerobic unit impacts the requirement of discharging standard. Microbial population in the activated sludge plays an important role in SCNremoval of coking wastewater treatment. However,the community structure has rarely been reported. Using SCN-as the sole carbon and energy source,the removal of 100 mg·L^（-1）,300 mg·L^（-1） and 600 mg·L^（-1） SCN-by activated sludge was studied and 454 sequencing technology was applied to investigate the biodiversity of SCN--degrading bacteria. The results showed that 100-600 mg·L^（-1） SCN-could be effectively removed by acclimated activated sludge,the higher SCN-concentration,the higher removal efficiency,but the lower bacterial community diversity indices. The bacterial communities in initial and acclimated sludge samples were mainly composed of Proteobacteria, Bacteroidetes, Chlorobi, Planctomycetes, Acidobacteria, Nitrospira, Firmicutes and Unclassified bacteria. Bacteroidetes and Proteobacteria were dominant phyla in the sludge. Thiobacillus was responsible for SCN-biodegradation in coking wastewater,and its abundance in three sludge samples was 3. 07%,8. 63% and 0. 27%,respectively. When the concentration of SCN-was less than 300 mg·L^（-1）,Thiobacillus was the main degrading bacteria. While at 600 mg·L^（-1） SCN-,low-abundance degrading bacteria might have synergistic degradation effect. These results have important significance for revealing SCN-removal mechanism in the coking wastewater treatment.