Key Laboratory of Marine Environment and Ecology, Ocean University of China, Ministry of Education, Qingdao, P.R. China.
Environ Technol. 2009 Nov;30(12):1241-8. doi: 10.1080/09593330903045115.
The sulphur-based bioleaching process using sulphur-oxidizing bacteria (SOB) has been demonstrated to be a feasible technology for removing heavy metals from contaminated sediments, but the excess sulphur application will lead to the re-acidification of bioleached sediments. The objective of the present study was to examine the effect of sulphur concentration on the bioleaching of heavy metals from contaminated sediments, with the ultimate purpose of minimizing the sulphur addition. The results showed that the inoculation of 7% of indigenous SOB, containing 3.6 x 10(8) colony forming units (CFU) mL(-1), and addition of elemental sulphur as a substrate (0.5 to 7.0 g L(-1)) resulted in a sharp decrease in sediment pH from an initial pH 8.0 to pH 1.4-2.4 and an increase in ORP (oxidation-reduction potential) from -10 mV to 500 mV within 10 days of bioleaching. Although the increase in sulphur concentration enhanced the rates of pH reduction and ORP elevation, the bioleaching process with the addition of 3.0 g L(-1) of sulphur was already sufficient to reach conditions of acidity (pH < 2.0) and ORP (500 mV) necessary for a satisfactory removal of metals, and, at day 10, 71.8% of Cu, 58.2% of Zn, and 25.3% of Cr were removed from the sediments. During the bioleaching process, Zn removal increased with a reduction in pH, whereas the removal of Cu and Cr increased not only with a reduction in pH but also with an increase in ORP. Results of sequential selective extraction indicated that the final levels of metal removals were dependent on their speciation distribution in the original sediments, and after bioleaching those unremoved metals in the bioleached sediments mainly existed in the residual fraction.
采用硫磺氧化菌（SOB）的硫磺基生物淋滤工艺已被证明是一种从污染沉积物中去除重金属的可行技术，但过量的硫磺应用会导致生物淋滤沉积物再次酸化。本研究的目的是研究硫磺浓度对污染沉积物中重金属生物淋滤的影响，最终目的是尽量减少硫磺的添加量。结果表明，接种 7%的土著 SOB，含 3.6×10(8)个菌落形成单位（CFU）mL(-1)，并添加元素硫作为基质（0.5 至 7.0 g L(-1)），可使沉积物 pH 值从初始 pH 值 8.0 急剧下降至 pH 值 1.4-2.4，氧化还原电位（ORP）从-10 mV 增加至 500 mV，生物淋滤 10 天内即可达到所需的酸度（pH 值 < 2.0）和 ORP（500 mV）条件。虽然增加硫磺浓度可以提高 pH 值降低和 ORP 值升高的速度，但添加 3.0 g L(-1)的硫磺已足以达到足以去除金属的条件，在第 10 天，从沉积物中去除了 71.8%的 Cu、58.2%的 Zn 和 25.3%的 Cr。在生物淋滤过程中，随着 pH 值的降低，Zn 的去除率增加，而 Cu 和 Cr 的去除率不仅随着 pH 值的降低而增加，而且随着 ORP 值的升高而增加。顺序选择性提取的结果表明，金属去除的最终水平取决于它们在原始沉积物中的形态分布，生物淋滤后，生物淋滤沉积物中未去除的金属主要存在于残余物中。
