生物淋滤结合类芬顿反应去除底泥中重金属

Removal of heavy metal from sediment by bioleaching combined with fenton-like reaction

  • 摘要: 结合Acidithiobacillus ferrooxidans生物淋滤与类芬顿反应以高效除去污染底泥中重金属.研究了15天生物淋滤周期中pH和ORP的变化,以及重金属Cu, Zn, Pb和Cd的去除情况.经过2天生物淋滤处理后,反应体系pH下降到2.5左右,此时向体系中加入五种不同剂量的H2O2(1 g/L, 3 g/L, 5 g/L, 7 g/L, 9 g/L),反应3 h完成类芬顿反应.结果表明,生物淋滤过程中pH值呈现下降趋势,从5.0降低到2.0左右,并维持在2.0附近波动.ORP从250 mV上升到700 mV附近,然后保持在700 mV左右.污染底泥经过15 d生物淋滤后,重金属去除率分别为:Cu-52.1%,Zn-65.8%,Pb-42.5%,Cd-83.25%.然而2天生物淋滤加3 h类芬顿反应的最大金属去除率达到:Cu-59.8%,Zn-70.0%,Pb-52.7%和Cd-85.3%.实验表明该方法可以提高重金属的去除率,并大大缩短反应时间,从而提供了一种相对高效的去除底泥中重金属的方法.

     

    Abstract: Feasibility of bioleaching by Acidithiobacillus ferrooxidans combined with Fenton-like reaction to efficiently remove heavy metals from contaminated sediment was investigated. The variation of pH and ORP during the 15-day bioleaching and the removal of heavy metal Cu, Zn, Pb and Cd were studied. After 2-day bioleaching, the reaction system pH decreased to approximately 2.5, then added five different dosages of H2O2(1 g/L, 3 g/L, 5 g/L, 7 g/L, 9 g/L)into the system to complete the Fenton-like reaction for 3 h. The results show that the pH presented a downtrend during the 15-day bioleaching, and decreased from 5.0 to 2.0, kept stable approximately at 2.0. However, ORP increased from 250 mV to around 700 mV, then maintained at around 700 mV. Through the 15-day bioleaching, the removal efficiencies of Cu, Zn, Pb and Cd were 52.1%, 65.8%, 42.5%, 83.25%, respectively. Nevertheless, the maximal removal efficiencies of thses metals with the combination of 2-day bioleaching and 3-hour Fenton-like reaction reached: Cu-59.8%, Zn-70.0%, Pb-52.7% and Cd-85.3%. The experience demonstrates that this method can dramaticlly enhance the removal efficiency of heavy metal, and greatly reduce the reaction time, which providing a relatively effective way to remove heavy metal from sediment.

     

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