生物除铬(VI)效果及机理探讨

Cr^(6+) REMOVAL FROM WASTEWATER BY A BIOSYSTEM AND ITS MECHANISM

以特定污泥挂膜的自制厌氧生物滤床系统具有良好的去铬(VI)能力。恒流泵最佳流量为47mL/min,外加碳源使废水COD约140mg/L,铬(VI)的浓度由60mg/L左右降到0.5mg/L以下(一级排放标准),需要4h,而对照组(未加碳源)需要14h。铬(VI)浓度由64.66mg/L提高到75.53mg/L时,对系统负面影响甚微,提高到95.47mg/L时,系统出水达标所需时间延长到7.5h。添加微量金属离子与未添加微量金属离子的情况相比,处理效率提高21.26%。分析试验表明:铬(VI)的去除途径可能是由生物还原作用将六价铬还原为三价铬,形成氢氧化铬沉积于微生物表面。

A self-made anaerobic bio-filter bed, which was inoculated with special sludge, showed a high efficiency in removing hexavalent chrome. When the optimal flux of the pump was 47mL/min and the COD in the wastewater was about 140 mg/L, it took 4 h to decrease the concentration of Cr6+ from above 60mg/L to under 0.5mg/L, while the time of the control group(without carbon source added) was 14 h. When the concentration of Cr6+ was increased from 64.66mg/L to 75.53mg/L, the negative effect, was less, and when the concentration of Cr6+ reached 95.47mg/L, the time was prolonged to 7.5 h. As compare with the contol system, the added trace metal system showed clear superiority that the removal rates of Cr6+ was increased by 21.26%. Some analysis also showed that hexavalent chrome was likely to be bio-deoxidized to trivalent chrome and form sediment of chrome hydroxide on the surface of microorganisms.