聚乙烯醇-海藻酸钠-活性炭固定化菌球处理二氯甲烷的研究

本研究以聚乙烯醇-海藻酸钠-活性炭为复合载体、自行筛选的高效降解菌Methylobacterium rhodesianum H13为目标菌制备固定化小球，用于去除二氯甲烷，同时优化了固定化小球的制备条件.结果表明，当聚乙烯醇浓度为8%，海藻酸钠浓度为5%，CaCl₂浓度为2%，活性炭浓度为1%，包菌量为0.6 g，钙化时间为8 h时，复合固定化细胞对DCM的降解速率达到最高为18.2 mg·L^-1·h^-1，同时活性炭的添加对小球的机械强度也有显著提升.与游离细胞相比，固定化细胞具有更好的热稳定性与pH稳定性，并且固定化细胞的重复利用性较好，连续处理9批底物后，DCM降解速率仍保持在13.4 mg·L^-1·h^-1以上.吸附动力学与等温线拟合结果显示，在固定化载体中加入1%活性炭后，小球对DCM的吸附量明显提高，而且吸附能在更短的时间内达到平衡.吸附动力学符合准二级反应动力学方程，复合载体对DCM的吸附遵循Langmuir吸附模型（R²>0.99）.

Removel of DCM by microorganism cells immobilized into polyvinyl alcohol-alginate-activated carbon beads

In this study, Methylobacterium rhodesianum H13 for dichloromethane (DCM) removal was immobilized into synthetic polyvinyl alcohol-alginate-activated carbon (PVA-SA-AC) beads. The optimal conditions for preparation were 8% PVA, 5% SA, 2% CaCl₂, 1% AC, 0.6 g bacterial biomass and 8 h crosslinking time. The average removal rate of DCM maximized at 18.2 mg·L^-1·h^-1. The mechanical strength of immobilized beads was improved by the addition of 1% AC. Compared with the free suspended cells, the immobilized cells showed a higher tolerance to temperature and pH. In the repeated batch experiment, the removal rate of DCM was still higher than 13.4 mg·L^-1·h^-1 after 9 cycles. Furthermore, the addition of 1% AC into PVA-SA immobilized beads improved adsorptive capacity and shorten adsorption time achieving the equilibrium. The adsorption process of DCM by PVA-SA-AC beads could be well fitted by the pseudo-second-order kinetic and Langmuir isotherm models (R²>0.99).