Zn(Ⅱ)对生物质碳源处理酸性矿山排水中厌氧微生物活性影响

Effect of Zn(Ⅱ) on Microbial Activity in Anaerobic Acid Mine Drainage Treatment System with Biomass as Carbon Source

通过厌氧批实验的方法,探讨了在硫酸盐还原菌(SRB)法处理模拟酸性矿山排水(AMD)的过程中,以油菜秸秆为碳源时,Zn2+浓度对SRB活性的影响.结果表明,在60 d实验中,以油菜秸秆为碳源时,当Zn2+初始浓度在73.7～196.8 mg.L-1范围时,SRB具有良好活性,实验结束时,pH从初始的5.0上升至中性范围,硫酸根还原率达到96%以上,同时Zn2+浓度降至0.05 mg.L-1以下.Tessier固体形态分类、场发射扫描电镜(FE-SEM)和X射线衍射仪(XRD)分析发现,Zn以有机物及硫化物的形态被固定,其中硫化物主要为闪锌矿(ZnS).当Zn2+初始浓度为262.97 mg.L-1时,SRB的活性受到强烈的抑制,实验结束时,pH从初始的5.0降至4.0左右,硫酸根还原率只有27%,Zn2+维持在较高浓度范围(25 mg.L-1).油菜秸秆可以作为SRB法长期处理AMD的缓释碳源,能为微生物生长繁殖提供物质和能量;秸秆的吸附性可降低Zn2+的生物毒性,使得SRB可以适应高浓度的Zn2+;SRB可以通过形成硫化物矿物的形式固定元素Zn.

In this study, with rape straw as carbon source, anaerobic batch experiments were executed to investigate the effect of Zn（Ⅱ） on the activity of sulphate reducing bacteria （SRB） in the microbial treatment of simulative acid mine drainage （AMD）. The results showed that during the 60 experimental days, when initial Zn2＋ concentrations were in the range of 73.7 to 196.8 mg·L-1, SRB had high culturalbility. At the end of these experiments, pH values rose from initial 5.0 to neutral, about 96% of sulphate was reduced and the concentrations of Zn2＋ reduced to 0.05 mg·L-1. The results of Tessier sequential extraction, field emission scanning electron microscope（FE-SEM） and X-ray diffraction（XRD） showed that Zn was found to be fixed through forming organic and sulphide （mainly sphalerite） compounds. For the experiment with high Zn2＋ concentration （262.97 mg·L-1）, at the end of experiments, pH values dropped from initial 5.0 to 4.0, only 27% of sulphate was only reduced and the concentrations of Zn2＋ kept in high range （25 mg·L-1）, the activity of SRB significantly inhibited. This study indicated that： 1 Rape straw can be used as slow-release carbon source for long term anaerobic AMD treatment; 2 Rape straw can decrease the toxicity of Zn2＋ to SRB through adsorption; 3 In anaerobic AMD treatment system, Zn can be fixed by sulphide minerals with mediation of SRB.