Soda Satoshi, Kanzaki Masaya, Yamamuara Shigeki, Kashiwa Masami, Fujita Masanori, Ike Michihiko
Division of Sustainable Energy and Environmental Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
J Biosci Bioeng. 2009 Feb;107(2):130-7. doi: 10.1016/j.jbiosc.2008.09.015.
A slurry bioreactor using a dissimilatory arsenate (As(V))-reducing bacterium is proposed for remediation of arsenic-contaminated soils. Bacterial As(V) reduction can cause arsenic extraction from the solid to the liquid phase because arsenite, As(III), is much less adsorptive than As(V). A mathematical model was developed incorporating the reversible sorption process of arsenic as well as bacterial growth and decay via As(V) reduction. A linear isotherm equation expressed the sorption process. The model included Haldane kinetics with high As(V) concentrations and cell inactivation by toxicity due to As(III). Extraction experiments used synthetic contaminated soils (forest soil, Soil SF, 1100 mg kg(-1); paddy soil, Soil SP, 1100 mg kg(-1)) and actual contaminated soils (Soil AH 2200 mg kg(-1) and Soil AL, 220 mg kg(-1)) at 5% w/v slurry concentration. Simulation results matched the observed changes of arsenic concentrations in the liquid phase. The respective extraction efficiencies of arsenic were 63%, 41%, 20%, and 55% for SF, SP, AH, and AL soils. Sensitivity analyses showed that the rate-limiting step was the desorption rate of As(V) from the solid to the liquid phase, rather than the As(V)-reducing rate. The proposed model provides a useful framework for understanding and predicting the extraction of arsenic from soil.
提出了一种使用异化砷酸盐（As(V)）还原菌的泥浆生物反应器来修复砷污染土壤。细菌还原As(V)会导致砷从固相萃取到液相，因为亚砷酸盐（As(III)）的吸附性远低于As(V)。开发了一个数学模型，该模型纳入了砷的可逆吸附过程以及通过As(V)还原实现的细菌生长和衰减。用线性等温线方程表示吸附过程。该模型包括高As(V)浓度下的霍尔丹动力学以及As(III)毒性导致的细胞失活。萃取实验使用了合成污染土壤（森林土壤，土壤SF，1100 mg kg(-1)；水稻土，土壤SP，1100 mg kg(-1)）和实际污染土壤（土壤AH 2200 mg kg(-1)和土壤AL，220 mg kg(-1)），泥浆浓度为5% w/v。模拟结果与液相中砷浓度的观测变化相匹配。SF、SP、AH和AL土壤中砷的各自萃取效率分别为63%、41%、20%和55%。敏感性分析表明，限速步骤是As(V)从固相到液相的解吸速率，而不是As(V)还原速率。所提出的模型为理解和预测土壤中砷的萃取提供了一个有用的框架。
