硫酸盐还原菌的脱硫性能和铁还原性能

陈明翔，周集体，路达,2，张玉

(1.大连理工大学 环境学院,工业生态与环境工程教育部重点实验室，辽宁 大连 116024； 2.河北大学 化学与环境科学学院,河北 保定 071002)

随着工业的发展，化石燃料的大量燃烧所产生的二氧化硫(SO2)和一氧化氮(NO)，造成了酸雨、臭氧层破坏、光化学烟雾等环境污染，并严重威胁人类的健康[1].SO2和NO一体化脱除技术，作为大气污染治理的发展趋势之一，已经得到广泛研究[2-3].目前，比较常见的烟气同时脱硫脱硝技术主要包括等离子体法、液相氧化法、光催化氧化法、络合吸收法、吸附法等[4-8].尽管这些方法有着诸多的优点，但仍有许多方面需要改进，如高能耗、高成本、存在二次污染等问题.生物法工业废气净化技术因其设备简单、投资及运行费用低、且无二次污染等优点日益受到人们的关注[1].目前，多数研究采用生物法单独脱除SO2或NO，而生物法同步脱硫脱硝尚处于实验探索阶段[3].

1 材料和方法

1.1 菌种

实验采用的SRB是由大连市春柳河污水处理厂的厌氧污泥经富集、驯化、反复稀释涂布而得.经16S rDNA测序和Blast分析表明，菌株与脱硫弧菌属(Desulfovibriosp.)的同源性最高，故命名为Desulfovibriosp.CMX.在GenBank上登录，其序列号为GU584224.在广东省微生物菌种保藏中心的保藏号为GIM1.765.

1.2 培养基

富集培养基：K2HPO4,0.50 g；NH4Cl,1.00 g；MgSO4·7H2O,2.00 g；Na2SO4,0.86 g；CaCl2,0.10 g；酵母浸粉，1.00 g；乳酸钠(质量分数为70%～80%)，5 mL；蒸馏水，1 000 mL，pH值调至7.00±0.20.在0.1 MPa，121 ℃下灭菌20 min.在培养基使用前用滤膜过滤灭菌加入0.10 g的维生素C.

基础培养基：Na2HPO4·12H2O，5.00 g；NaH2PO4·2H2O，2.20 g；酵母浸粉，1.00 g；乳酸钠(质量分数为70%～80%)，5 mL；蒸馏水，1 000 mL.在0.1 MPa，121 ℃下灭菌20 min.在培养基使用前用滤膜过滤灭菌加入0.10 g的维生素C.

1.3 菌株脱硫性能的优化

1.3.1 pH值对D.sp.CMX的脱硫性能的影响

1.3.2 不同碳源对D.sp.CMX脱硫性能的影响

1.4 菌株Fe(Ⅲ)EDTA还原能力的考察

分别将0，5，15，25 mmol/L的Fe(Ⅲ)EDTA加入100 mL基础培养基中，并将D.sp.CMX(细胞蛋白质量浓度为20.00 mg/L)分别厌氧接种于初始Fe(Ⅲ)EDTA浓度不同的培养基中，在pH=7、温度为30 ℃的条件下厌氧培养，并定期取样测定其蛋白生长量、亚铁(Fe2+)和总铁含量.

1.5 分析方法

2 结果和讨论

2.1 pH对D.sp.CMX的脱硫性能的影响

图1 pH值不同时D.sp.CMX的脱硫性能Fig.1 Sulfate reducing performances of D.sp.CMX at different pH values

图2 不同碳源时D.sp.CMX的脱硫性能Fig.2 Sulfate reducing performances of D.sp.CMX at different carbon sources

2.2 碳源对D.sp.CMX的脱硫性能的影响

2.3 初始质量浓度对D.sp.CMX的脱硫性能的影响

ρ/(g·L-1)图3 初始的质量浓度不同时D.sp.CMX的脱硫性能Fig.3 Sulfate reducing performances of D.sp.CMX at different sulfate concentrations

2.4 D.sp.CMX的铁还原能力的考察

图4 D.sp.CMX的铁还原能力Fig.4 Ferric reducing capacity of D.sp.CMX

图5 D.sp.CMX在Fe(Ⅲ)EDTA中的生长情况Fig.5 Growth of D.sp.CMX in Fe(Ⅲ)EDTA solution

SRB可以直接将Fe(Ⅲ)、尤其是水溶态的Fe(Ⅲ)生物还原，但是，又有研究表明，25 mmol/L的Fe(Ⅲ)EDTA不是一个合适的电子受体，大部分的异养铁还原微生物无法还原25 mmol/L的Fe(Ⅲ)EDTA[23-25].而在本实验中，菌株D.sp.CMX在25 mmol/L的Fe(Ⅲ)EDTA溶液中，也可以发生异养的铁还原.随着Fe(Ⅲ)EDTA浓度的升高，D.sp.CMX在22 h时的蛋白浓度反而降低，这可能是由络合剂对SRB的毒性导致的，已有研究证明，EDTA、柠檬酸都对SRB的活性有一定的抑制作用[26].

3 结论

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