Effect of pH regulation on the formation of biogenic schwertmannite driven by Acidithiobacillus ferrooxidans and its arsenic removal ability
2022
Zhou, Jia-Xing | Zhou, Yu-Jun | Zhang, Jian | Dong, Yan | Liu, Fen-Wu | Wu, Zhi-Hui | Bi, Wen-Long | Qin, Jun-Mei
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.
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