一价阳离子和水溶性有机质对生物沥浸中次生铁矿物形成的影响

Effects of Monovalent Cation and Dissolved Organic Matter on the Formation of Biogenic Secondary Iron Minerals in Bioleaching System

在嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)作用下,污泥生物沥浸体系中常会有次生铁矿物形成,这些矿物对污泥脱水和重金属溶出有重要影响。本研究模拟生物沥浸体系,考察了一价阳离子(K+、NH4+、Na+)和污泥DOM(dissolved organic matter)对次生铁矿物形成的影响。结果表明,一价阳离子生成次生黄铁矾类矿物的能力迥异,其中K+的成矾能力最强,120 mmol/L NH4+和80 mmol/L Na+会抑制体系中黄钾铁矾形成。在1.6 mmol/L K+-120 mmol/L NH4+-40 mmol/L Na+和1.6 mmol/L K+-80 mmol/L NH4+-80 mmol/L Na+两个处理所得矿物的结晶度均低于1.6 mmol/L K+-80 mmol/L NH4+-40 mmol/L Na+处理所得矿物的结晶度。另外,在50 mg/L DOM(以DOC计)存在的生物氧化体系,Fe2+最大氧化速率为4.96 h-1,比没有DOM存在时降低48.1%,矿物结晶度也明显低于后者。可见,过高的一价阳离子和DOM含量会影响A.ferrooxidans菌生理生化活性,降低Fe2+氧化速率,继而影响Fe3+供应,使微环境中的黄铁矾形成动力发生改变,最终在一定程度上影响了次生铁矿物的形成。

Secondary iron minerals were formed under the effect of Acidithiobacillus ferrooxidans,which having major impacts on the sludge dewatering and heavy metals leaching in bioleaching system.Two simulative experiments were carried out to study the effect of monovalent cation（K^＋,NH4^＋,and Na^＋） and sludge dissolved organic matter（DOM） on the secondary iron minerals formation.The results indicated that monovalent cation ability varied widely on the formation of biogenic secondary iron minerals facilitated by A.ferrooxidans,and K^＋ was the strongest.However,high concentrations of NH4^＋ and Na^＋ could inhibit the formation of potassium-jarosite.The crystallinity of the mineral formed as 1.6 mmol/L of K^＋,120 mmol/L of NH4^＋,and 40 mmol/L of Na^＋ or 1.6 mmol/L of K^＋,80 mmol/L of NH4^＋,and 80 mmol/L of Na＋ was lower than that of the mineral formed as 1.6 mmol/L of K^＋,80 mmol/L of NH4^＋,and 40 mmol/L of Na^＋.The largest Fe^2＋ oxidation rate was 4.96 h-1 in the presence of 50 mg/L of DOM（presented as DOC）,which reduced 48.1% of that by the treatment without DOM,and the mineral crystallinity was also poorer than latter.Therefore,effects of high concentrations of monovalent cation and DOM on physiological and biochemical activity of A.ferrooxidans were significant,and could reduce the maximum oxidation rate of Fe^2＋.Furthermore,with the decrease of Fe^2＋,the total amount of Fe^3＋ formed by bacteria and the driving force of jarosite-forming on microenvironment could decreased,To a certain extent,the secondary iron minerals formed in the biological oxidation system depended on the monovalent cation and DOM.