Department of Engineering Science, University of Oxford, Parks Road, Oxford OX1 3PJ, UK.
Water Res. 2012 May 1;46(7):2395-404. doi: 10.1016/j.watres.2012.02.006. Epub 2012 Feb 13.
Disposal of operationally exhausted metal working fluids (MWF) through a biological route is an attractive option, since it is effective with relatively low energy demands. However, it is enormously challenging since these fluids are chemically complex, including the addition of toxic biocides which are added specifically to retard bio-deterioration whilst the fluids are operational. Nano-sized elemental iron represents a new generation of environmental remediation technologies. Laboratory scale batch studies were performed to test the degradation ability of a semi-synthetic metalworking fluid (MWF) wastewater (which was found to be resistant to initial bacterial treatment in specifically established bioreactors) by employing a novel hybrid approach. The approach was to combine the synergistic effects of nano zerovalent iron (nZVI) induced oxidation, followed by biodegradation, specifically for the remediation of recalcitrant components of MWF effluent. Addition of nZVI particles to oxygenated wastewater resulted in oxidation of organic contaminants present. Our studies confirmed 78% reduction in chemical oxygen demand (COD) by nZVI oxidation at pH 3.0 and 67% reduction in neutral pH (7.5), and 85% concurrent reduction in toxicity. Importantly, this low toxicity made the nZVI treated effluent more amenable for a second stage biological oxidation step. An overall COD reduction of 95.5% was achieved by the novel combined treatment described, demonstrating that nZVI oxidation can be exploited for enhancing the biodegradability of a recalcitrant wastewater in treatment processes.
通过生物途径处理运行耗尽的金属加工液（MWF）是一种很有吸引力的选择，因为它的效果好，所需能量相对较低。然而，这是一个巨大的挑战，因为这些流体化学性质复杂，包括添加有毒的杀生剂，这些杀生剂专门添加到运行中的流体中以延缓生物降解。纳米尺寸的元素铁代表了新一代的环境修复技术。进行了实验室规模的分批研究，以测试一种半合成金属加工液（MWF）废水的降解能力（该废水在专门建立的生物反应器中初始细菌处理时被发现具有抗性），采用了一种新的混合方法。该方法是将纳米零价铁（nZVI）诱导的氧化与生物降解相结合，专门用于修复 MWF 废水的难生物降解成分。将 nZVI 颗粒添加到含氧废水中会导致存在的有机污染物氧化。我们的研究证实，在 pH 3.0 时，nZVI 氧化可将化学需氧量（COD）降低 78%，在中性 pH（7.5）时降低 67%，同时毒性降低 85%。重要的是，这种低毒性使得 nZVI 处理后的废水更适合进行第二阶段的生物氧化步骤。通过所描述的新型组合处理，COD 总去除率达到 95.5%，表明 nZVI 氧化可用于增强难生物降解废水在处理过程中的生物降解性。
