Maiti Soumen K, Bera Debabrata, Chattopadhyay Parimal, Ray Lalitagauri
Department of Food Technology and Biochemical Engineering, Jadavpur University, Kolkata 700032, India.
Appl Biochem Biotechnol. 2009 Nov;159(2):488-504. doi: 10.1007/s12010-008-8519-2. Epub 2009 Mar 31.
Due to technological advancement, environment suffers from untreated toxic heavy metal bearing effluent coming from different industries. Chromium (VI) is one of those heavy metals having adverse impact on ecological balance, human, and plant health because of its carcinogenic properties. Biosorption is presented as an alternative to traditional technologies which are costly and inefficient for treatment of industrial wastes containing low amount of heavy metals. In this study, bioremediation of Cr (VI) ions by immobilized Bacillus cereus M(1) (16) was investigated in a laboratory scale packed bed up-flow column reactor. The effect of important parameters, such as the inlet flow rate, influent concentration, and effective bed height, has been studied. External mass transfer, surface adsorption, and intrabead mass transfer were also studied to conclude the rate limiting step for removal of Cr (VI) and to determine the process parameters which are important for biosorption optimization. The external mass transfer coefficient was calculated at different flow rates (6.51 x 10(-2) to 7.58 x 10(-2) cm/min). Using the model, the surface adsorption rate constant (k(ad)) and the intrabead mass transfer coefficient (k (i)) were predicted as 0.0267 x 10(-3) and 0.7465 x 10(-3) l/g/min, respectively. Both are much lower than the external mass transfer coefficient (k(e)). The surface adsorption phenomenon is acting as the rate-limiting step due to its high resistance for removal of Cr (VI).
由于技术进步，环境正遭受来自不同行业未经处理的含有毒重金属废水的影响。铬（VI）是那些因其致癌特性而对生态平衡、人类和植物健康产生不利影响的重金属之一。生物吸附作为一种替代传统技术的方法被提出，传统技术处理含少量重金属的工业废物成本高且效率低。在本研究中，在实验室规模的填充床上流式柱反应器中研究了固定化蜡样芽孢杆菌M(1) (16)对Cr（VI）离子的生物修复作用。研究了重要参数如入口流速、进水浓度和有效床层高度的影响。还研究了外部传质、表面吸附和颗粒内传质，以确定去除Cr（VI）的速率限制步骤，并确定对生物吸附优化很重要的工艺参数。在不同流速（6.51×10(-2)至7.58×10(-2) cm/min）下计算了外部传质系数。使用该模型，预测表面吸附速率常数（k(ad)）和颗粒内传质系数（k (i)）分别为0.0267×10(-3)和0.7465×10(-3) l/g/min。两者均远低于外部传质系数（k(e)）。由于其对Cr（VI）去除的高阻力，表面吸附现象成为速率限制步骤。
