Gu Xiangyang, Wong Jonathan W C
Department of Biology, Hong Kong Baptist University, Kowloon Tong, Hong Kong SAR, People's Republic of China.
Environ Sci Technol. 2004 May 15;38(10):2934-9. doi: 10.1021/es0347134.
Significant inhibitory effects of the filtrate medium of anaerobically digested sewage sludge on iron oxidation by Acidithiobacillus ferrooxidans ANYL-1 were observed in our preliminary experiments, indicating the presence of inhibitory substances in anaerobically digested sewage sludge. The objectives of the present study were to identify the possible inhibitory substances and to evaluate their impacts on metal solubilization during bioleaching of sewage sludge. The results showed that the concentrations of total reducing sugars, all tested metal ions, and anions were too low to suppress iron oxidation, and only organic acids, especially acetic and propionic acids, were found at concentrations higher than their inhibitory levels. The presence of 10.8 mM acetic acid and 9.88 mM propionic acid in sewage sludge (sludge N) led to long lag periods of 6 and 7 days for solubilization of Cu and Cr, respectively, as compared to a lag period of only 1 day in the control and another sludge (sludge S) with a low level of organic acids. Meanwhile the leaching time for maximum solubilization of Zn also extended to 6 days in the presence of organic acids as compared to 3 days in the control. Acetic and propionic acids posed an unfavorable bioleaching condition for anaerobically digested sewage sludge; therefore, further studies are required to explore the means to remove the inhibitory effects to improve the heavy metal bioleaching efficiency.
在我们的初步实验中，观察到厌氧消化污水污泥的滤液培养基对嗜酸氧化亚铁硫杆菌ANYL-1的铁氧化具有显著抑制作用，这表明厌氧消化污水污泥中存在抑制性物质。本研究的目的是确定可能的抑制性物质，并评估它们对污水污泥生物沥滤过程中金属溶解的影响。结果表明，总还原糖、所有测试金属离子和阴离子的浓度过低，无法抑制铁氧化，仅发现有机酸，尤其是乙酸和丙酸的浓度高于其抑制水平。与对照和另一种低有机酸水平的污泥（污泥S）仅1天的滞后期相比，污水污泥（污泥N）中10.8 mM乙酸和9.88 mM丙酸的存在分别导致铜和铬溶解的滞后期长达6天和7天。同时，与对照中3天相比，在有机酸存在下锌最大溶解的浸出时间也延长至6天。乙酸和丙酸对厌氧消化污水污泥构成了不利的生物沥滤条件；因此，需要进一步研究探索消除抑制作用的方法，以提高重金属生物沥滤效率。
