Purpose of Review

Hexavalent chromium, Cr(VI), and trivalent chromium, Cr(III), are two chromium compounds with practical importance due to their high occurrence and solubility in the environment. Current Cr(VI) treatment techniques involve chemical reduction of Cr(VI) to Cr(III), which posed serious threat to workers and environment notably from long exposure and toxic fumes.

Recent Findings

Numerous reports have demonstrated the feasibility of using biological processes for the treatment of Cr(VI) industrial effluents by either pure culture or a consortium of Cr(VI)-reducing bacteria, with various degrees of success. Among issues to be considered include high cost of nutrient for the bacteria, low Cr resistant-reducing ability of environmental isolates, difficulty in scaling up finding in the laboratory to pilot scale and on-site application as well as the understanding on the dynamic underlying mechanisms for bacterial Cr(VI) reduction.

Summary

This review highlights cytotoxicity and genotoxicity properties of Cr(VI), which form the biggest motivation for continuous development in the field of Cr(VI) treatment technologies, latest finding in aerobic and anaerobic bacterial reduction of Cr(VI), operational challenges for bacterial Cr(VI) reduction, and some examples for laboratory-scale and pilot-scale evaluation of free and immobilized (biofilm) cells of Cr(VI) resistant-reducing bacteria.

中文翻译：

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Cr（VI）的细菌还原：操作挑战和可行性

审查目的

六价铬Cr（VI）和三价铬Cr（III）是两种铬化合物，由于它们的高发生率和在环境中的溶解度，因此具有实际意义。当前的六价铬处理技术涉及将六价铬化学还原为三价铬，特别是长时间接触和有毒烟雾对工人和环境构成严重威胁。

最近的发现

大量报告证明了通过纯培养物或减少Cr（VI）的细菌财团使用生物工艺处理Cr（VI）工业废水的可行性，并获得了不同程度的成功。需要考虑的问题包括细菌的营养成本高，环境分离株的抗Cr还原能力低，难以扩大实验室规模以进行中试规模和现场应用以及对动态潜在机制的理解用于减少细菌中的六价铬。

概要

这篇综述重点介绍了六价铬的细胞毒性和遗传毒性特性，这是六价铬处理技术领域不断发展的最大动力，有氧和厌氧细菌还原六价铬的最新发现，细菌的操作挑战Cr（VI）还原，以及一些实验室规模和中试规模的抗Cr（VI）还原细菌的游离和固定化（生物膜）细胞评估的示例。