硫酸鹽還原菌的脫硫性能和鐵還原性能

陳明翔，周集體，路達,2，張玉

(1.大連理工大學 環(huán)境學院,工業(yè)生態(tài)與環(huán)境工程教育部重點實驗室，遼寧 大連 116024； 2.河北大學 化學與環(huán)境科學學院,河北 保定 071002)

隨著工業(yè)的發(fā)展，化石燃料的大量燃燒所產生的二氧化硫(SO2)和一氧化氮(NO)，造成了酸雨、臭氧層破壞、光化學煙霧等環(huán)境污染，并嚴重威脅人類的健康[1].SO2和NO一體化脫除技術，作為大氣污染治理的發(fā)展趨勢之一，已經得到廣泛研究[2-3].目前，比較常見的煙氣同時脫硫脫硝技術主要包括等離子體法、液相氧化法、光催化氧化法、絡合吸收法、吸附法等[4-8].盡管這些方法有著諸多的優(yōu)點，但仍有許多方面需要改進，如高能耗、高成本、存在二次污染等問題.生物法工業(yè)廢氣凈化技術因其設備簡單、投資及運行費用低、且無二次污染等優(yōu)點日益受到人們的關注[1].目前，多數研究采用生物法單獨脫除SO2或NO，而生物法同步脫硫脫硝尚處于實驗探索階段[3].

1 材料和方法

1.1 菌種

實驗采用的SRB是由大連市春柳河污水處理廠的厭氧污泥經富集、馴化、反復稀釋涂布而得.經16S rDNA測序和Blast分析表明，菌株與脫硫弧菌屬(Desulfovibriosp.)的同源性最高，故命名為Desulfovibriosp.CMX.在GenBank上登錄，其序列號為GU584224.在廣東省微生物菌種保藏中心的保藏號為GIM1.765.

1.2 培養(yǎng)基

富集培養(yǎng)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；乳酸鈉(質量分數為70%～80%)，5 mL；蒸餾水，1 000 mL，pH值調至7.00±0.20.在0.1 MPa，121 ℃下滅菌20 min.在培養(yǎng)基使用前用濾膜過濾滅菌加入0.10 g的維生素C.

基礎培養(yǎng)基：Na2HPO4·12H2O，5.00 g；NaH2PO4·2H2O，2.20 g；酵母浸粉，1.00 g；乳酸鈉(質量分數為70%～80%)，5 mL；蒸餾水，1 000 mL.在0.1 MPa，121 ℃下滅菌20 min.在培養(yǎng)基使用前用濾膜過濾滅菌加入0.10 g的維生素C.

1.3 菌株脫硫性能的優(yōu)化

1.3.1 pH值對D.sp.CMX的脫硫性能的影響

1.3.2 不同碳源對D.sp.CMX脫硫性能的影響

1.4 菌株Fe(Ⅲ)EDTA還原能力的考察

分別將0，5，15，25 mmol/L的Fe(Ⅲ)EDTA加入100 mL基礎培養(yǎng)基中，并將D.sp.CMX(細胞蛋白質量濃度為20.00 mg/L)分別厭氧接種于初始Fe(Ⅲ)EDTA濃度不同的培養(yǎng)基中，在pH=7、溫度為30 ℃的條件下厭氧培養(yǎng)，并定期取樣測定其蛋白生長量、亞鐵(Fe2+)和總鐵含量.

1.5 分析方法

2 結果和討論

2.1 pH對D.sp.CMX的脫硫性能的影響

圖1 pH值不同時D.sp.CMX的脫硫性能Fig.1 Sulfate reducing performances of D.sp.CMX at different pH values

圖2 不同碳源時D.sp.CMX的脫硫性能Fig.2 Sulfate reducing performances of D.sp.CMX at different carbon sources

2.2 碳源對D.sp.CMX的脫硫性能的影響

2.3 初始質量濃度對D.sp.CMX的脫硫性能的影響

ρ/(g·L-1)圖3 初始的質量濃度不同時D.sp.CMX的脫硫性能Fig.3 Sulfate reducing performances of D.sp.CMX at different sulfate concentrations

2.4 D.sp.CMX的鐵還原能力的考察

圖4 D.sp.CMX的鐵還原能力Fig.4 Ferric reducing capacity of D.sp.CMX

圖5 D.sp.CMX在Fe(Ⅲ)EDTA中的生長情況Fig.5 Growth of D.sp.CMX in Fe(Ⅲ)EDTA solution

SRB可以直接將Fe(Ⅲ)、尤其是水溶態(tài)的Fe(Ⅲ)生物還原，但是，又有研究表明，25 mmol/L的Fe(Ⅲ)EDTA不是一個合適的電子受體，大部分的異養(yǎng)鐵還原微生物無法還原25 mmol/L的Fe(Ⅲ)EDTA[23-25].而在本實驗中，菌株D.sp.CMX在25 mmol/L的Fe(Ⅲ)EDTA溶液中，也可以發(fā)生異養(yǎng)的鐵還原.隨著Fe(Ⅲ)EDTA濃度的升高，D.sp.CMX在22 h時的蛋白濃度反而降低，這可能是由絡合劑對SRB的毒性導致的，已有研究證明，EDTA、檸檬酸都對SRB的活性有一定的抑制作用[26].

3 結論

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