Quintelas C, Fernandes B, Castro J, Figueiredo H, Tavares T
IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, Braga, Portugal.
J Hazard Mater. 2008 May 1;153(1-2):799-809. doi: 10.1016/j.jhazmat.2007.09.027. Epub 2007 Sep 12.
The ability of three different bacterial species supported on granular activated carbon (GAC) to remove hexavalent chromium from low concentration liquid solutions was investigated, in batch and column studies. The microorganisms tested were Cr(VI) reducing types: Streptococcus equisimilis (CECT 926), Bacillus coagulans (CECT 12) and Escherichia coli (CECT 515). The results showed metal uptake values of 5.82, 5.35 and 4.12 mg/g(bios.), respectively, for S. equisimilis, B. coagulans and E. coli, for an initial metal concentration of 100 mg/l. In the same order and for the initial concentration of 50 mg/l, metal uptake values were 2.33, 1.98 and 3.60 mg/g(bios.). Finally, for the initial metal concentration of 10 mg/l, those values were, respectively, 0.66, 1.51 and 1.12 mg/g(bios.). Studies made with an industrial effluent, with the aim of testing these biofilms in a real situation, showed values of Cr uptake of 0.083, 0.090 and 0.110 mg/g(bios.), respectively, for S. equisimilis, B. coagulans and E. coli, for an initial concentration of 4.2 mg/l of total Cr. The quantification of polysaccharides, playing a key role in the whole process, was made and it was concluded that the production of polysaccharides is higher for B. coagulans followed by S. equisimilis and E. coli (9.19, 7.24 and 4.77 mg/g(bios.)). The batch studies data were described using the Freundlich, Langmuir, Redlich-Peterson, Dubinin-Radushkevich, Sips and Toth model isotherms. The best fit was obtained with Sips and Toth model isotherms, respectively, for the S. equisimilis and for the B. coagulans biofilms. For the E. coli biofilm the Freundlich, Redlich-Peterson, Sips and Toth models fitted very well to the experimental data. The Adams-Bohart, Wolborska and Yoon and Nelson models were applied to column studies data. Those models were found suitable for describing the dynamic behaviour of the columns with respect to the inlet chromium concentration. Obtained results showed that the biofilms tested are very promising for the removal of Cr(VI) in diluted industrial wastewater. Despite differences in the cell wall structure and composition, the three bacteria exhibit comparable sorption affinities towards chromium, in the open systems studies. The Gram-positive bacteria tested (B. coagulans and S. equisimilis) presented best metal removal percentages in batch studies.
在分批和柱式研究中，研究了负载在颗粒活性炭（GAC）上的三种不同细菌物种从低浓度液体溶液中去除六价铬的能力。所测试的微生物是六价铬还原类型：马疫链球菌（CECT 926）、凝结芽孢杆菌（CECT 12）和大肠杆菌（CECT 515）。结果表明，对于初始金属浓度为100mg/L的情况，马疫链球菌、凝结芽孢杆菌和大肠杆菌的金属吸收值分别为5.82、5.35和4.12mg/g（生物量）。以相同顺序，对于初始浓度为50mg/L的情况，金属吸收值分别为2.33、1.98和3.60mg/g（生物量）。最后，对于初始金属浓度为10mg/L的情况，这些值分别为0.66、1.51和1.12mg/g（生物量）。为了在实际情况下测试这些生物膜，对工业废水进行的研究表明，对于初始总铬浓度为4.2mg/L的情况，马疫链球菌、凝结芽孢杆菌和大肠杆菌的铬吸收值分别为0.083、0.090和0.110mg/g（生物量）。对在整个过程中起关键作用的多糖进行了定量，得出结论，凝结芽孢杆菌的多糖产量最高，其次是马疫链球菌和大肠杆菌（分别为9.19、7.24和4.77mg/g（生物量））。使用Freundlich、Langmuir、Redlich-Peterson、Dubinin-Radushkevich、Sips和Toth模型等温线描述了分批研究数据。分别对马疫链球菌和凝结芽孢杆菌生物膜，Sips和Toth模型等温线拟合效果最佳。对于大肠杆菌生物膜，Freundlich、Redlich-Peterson、Sips和Toth模型与实验数据拟合得非常好。将Adams-Bohart、Wolborska以及Yoon和Nelson模型应用于柱式研究数据。发现这些模型适用于描述柱相对于进水铬浓度的动态行为。所得结果表明，所测试的生物膜对于去除稀释工业废水中的六价铬非常有前景。在开放系统研究中，尽管细胞壁结构和组成存在差异，但这三种细菌对铬表现出相当的吸附亲和力。在分批研究中，所测试的革兰氏阳性细菌（凝结芽孢杆菌和马疫链球菌）的金属去除率最高。
