Water Management Department, Faculty of Civil engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628CN Delft, The Netherlands.
Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen DK-1350, Denmark.
Water Res. 2021 Jan 1;188:116531. doi: 10.1016/j.watres.2020.116531. Epub 2020 Oct 17.
Arsenic (As) is a toxic element present in many (ground)water sources in the world. Most conventional As removal techniques require pre-oxidation of the neutral arsenite (As(III)) species to the negatively charged arsenate (As(V)) oxyanion to optimize As removal and minimize chemical use. In this work, a novel, continuous-flow As removal system was developed that combines biological As(III) oxidation by bacteria with Fe electrocoagulation (EC), an Fe(0)-based electrochemical technology that generates reactive Fe(III) precipitates to bind As. The bio-integrated FeEC system (bio-FeEC) showed effective oxidation and removal of 150 µg/L As(III), without the need of chemicals. To remove As to below the WHO guideline of 10 µg/L, 10 times lower charge dosage was required for the bio-FeEC system compared to conventional FeEC. This lower Fe dosage requirement reduced sludge production and energy consumption. The As(III) oxidizing biomass was found to consist of bacteria belonging to Comamonadaceae, Rhodobacteraceae and Acidovorax, which are capable of oxidizing As(III) and are common in drinking water biofilms. Characterization of the As-laden Fe solids by X-ray absorption spectroscopy indicated that both bio-FeEC and conventional FeEC produced solids consistent with a mixture of lepidocrocite and 2-line ferrihydrite. Arsenic bound to the solids was dominantly As(V), but a slightly higher fraction of As(V) was detected in the bio-FeEC solids compared to the conventional FeEC.
砷（As）是世界上许多（地下水）水源中存在的一种有毒元素。大多数常规的除砷技术都需要将中性亚砷酸盐（As(III)）物种预先氧化为带负电荷的砷酸盐（As(V)）氧阴离子，以优化除砷效果并最小化化学物质的使用。在这项工作中，开发了一种新颖的、连续流动的除砷系统，该系统将细菌的生物 As(III)氧化与铁电凝聚（EC）相结合，铁电凝聚是一种基于 Fe(0)的电化学技术，可生成活性 Fe(III)沉淀物以结合 As。生物整合铁电凝聚系统（bio-FeEC）在无需使用化学物质的情况下，有效地氧化和去除了 150μg/L 的 As(III)。为了将 As 去除到世界卫生组织规定的 10μg/L 以下，bio-FeEC 系统所需的铁剂量比传统的 FeEC 低 10 倍。这种较低的铁剂量要求减少了污泥产量和能源消耗。发现用于 As(III)氧化的生物量由属于 Comamonadaceae、Rhodobacteraceae 和 Acidovorax 的细菌组成，这些细菌能够氧化 As(III)，并且在饮用水生物膜中很常见。通过 X 射线吸收光谱对含砷铁固体的表征表明，bio-FeEC 和传统 FeEC 都产生了与针铁矿和 2 线水铁矿混合物一致的固体。与固体结合的砷主要为 As(V)，但在 bio-FeEC 固体中检测到的 As(V)比例略高于传统 FeEC。
