Water Research Institute, National Research Council of Italy (IRSA - CNR), Via Salaria, km 29.300, Monterotondo, Rome 00015, Italy.
Department for Innovation in Agroforestry and Biological systems (DIBAF), University of Tuscia, Viterbo, Italy.
Sci Total Environ. 2019 Feb 15;651(Pt 1):93-102. doi: 10.1016/j.scitotenv.2018.09.176. Epub 2018 Sep 14.
Arsenic (As) contamination in drinking water represents a worldwide threat to human health. During last decades, the exploitation of microbial As-transformations has been proposed for bioremediation applications. Among biological methods for As-contaminated water treatment, microbial As(III)-oxidation is one of the most promising approaches since it can be coupled to commonly used adsorption removal technologies, without requiring the addition of chemicals and producing toxic by-products. Despite the As(III) oxidation capability has been described in several bacterial pure or enrichment cultures, very little is known about the real potentialities of this process when mixed microbial communities, naturally occurring in As contaminated waters, are used. This study highlighted the contribution of native groundwater bacteria to As(III)-oxidation in biofilters, under conditions suitable for a household-scale treatment system. This work elucidated the influence of a variety of experimental conditions (i.e., various filling materials, flow rates, As(III) inflow concentration, As(III):As(V) ratio, filter volumes) on the microbially-mediated As(III)-oxidation process in terms of oxidation efficiency and rate. The highest oxidation efficiencies (up to 90% in 3 h) were found on coarse sand biofilters treating total initial As concentration of 100 μg L. The detailed microbial characterization of the As(III) oxidizing biofilms revealed the occurrence of several OTUs affiliated with families known to oxidize As(III) (e.g., Burkholderiaceae, Comamonadaceae, Rhodobacteraceae, Xanthomonadaceae). Furthermore, As-related functional genes increased in biofilter systems in line with the observed oxidative performances.
饮用水中的砷（As）污染对全球人类健康构成了威胁。在过去的几十年中，人们已经提出利用微生物的砷转化作用来进行生物修复应用。在处理受砷污染的水的生物方法中，微生物砷（III）氧化是最有前途的方法之一，因为它可以与常用的吸附去除技术结合使用，而无需添加化学物质和产生有毒副产物。尽管已经在几种细菌纯培养或富集培养物中描述了 As(III)氧化能力，但当使用自然存在于受砷污染水中的混合微生物群落时，对该过程的实际潜力知之甚少。本研究强调了在适合家庭规模处理系统的条件下，天然地下水中的细菌对生物滤器中 As(III)氧化的贡献。这项工作阐明了各种实验条件（即各种填充材料、流速、As(III)入口浓度、As(III):As(V) 比、滤器体积）对微生物介导的 As(III)氧化过程的影响，包括氧化效率和速率。在处理初始总砷浓度为 100μg/L 的情况下，粗砂生物滤器的氧化效率最高（3 小时内高达 90%）。对氧化 As(III)的生物膜的详细微生物特征分析揭示了一些与已知氧化 As(III)的科（如 Burkholderiaceae、Comamonadaceae、Rhodobacteraceae、Xanthomonadaceae）有关的 OTUs 的发生。此外，与观察到的氧化性能一致，生物滤器系统中的 As 相关功能基因增加。
