ABSTRACT

The effect of pH regulation on schwertmannite bio-synthesis and its As removal ability were investigated in this study. The total Fe precipitation efficiency in a conventional schwertmannite bio-synthesis system (CK) reached 26.5%, with a mineral weight of 5.21 g/L and a mineral specific surface area of 3.18 m²/g. The total Fe precipitation efficiency increased to 88.4–95.8%, the mineral weight increased to 17.10–18.62 g/L, and the specific surface area increased to 3.61–90.67 m²/g of five different treatments in which the system pH was continually adjusted to 2.50, 2.70, 2.90, 3.10, and 3.30 every 3 h, respectively. The very small amounts of schwertmannite were transformed to goethite when the system pH was periodically adjusted to 2.90, 3.10 and 3.30. The increased specific surface area of bio-schwertmannite was due to the contribution of mesopores, with most pores having a diameter of 2–20 nm. For actual As-containing groundwater (27.4 μg/L), the As removal rate was 52.9% for bio-schwertmannite collected from the CK system. However, the removal rate of As increased to 92.7–97.8% for minerals which were collected after five adjusted pH treatments. The outcomes of this study provide a fresh insight into the bio-synthesis regulation of schwertmannite, and have great significance for the treatment of As-containing groundwater.

摘要

本研究考察了 pH 调节对施韦特曼石生物合成及其除砷能力的影响。常规施韦特曼石生物合成系统（CK）的总Fe沉淀效率达到26.5%，矿物重量为5.21 g/L，矿物比表面积为3.18 m ² /g。铁总沉淀效率提高到88.4~95.8%，矿物重量提高到17.10~18.62 g/L，比表面积提高到3.61~90.67 m ²/g 的五种不同处理，其中系统 pH 值连续每 3 小时分别调整为 2.50、2.70、2.90、3.10 和 3.30。当系统的 pH 值定期调整为 2.90、3.10 和 3.30 时，极少量的施韦特曼石转化为针铁矿。生物施韦特曼石比表面积的增加是由于中孔的贡献，大多数孔的直径为2-20 nm，对于实际含As地下水（27.4 μg/L），As去除率为52.9 % 为从 CK 系统收集的生物施韦特曼石。然而，经过 5 次调节 pH 处理后收集的矿物，As 的去除率增加到 92.7-97.8%。这项研究的结果为施韦特曼石的生物合成调控提供了新的见解，