Effect of pH regulation on the formation of biogenic schwertmannite driven by Acidithiobacillus ferrooxidans and its arsenic removal ability

• Published in: Environmental technology Vol. 43; no. 24; pp. 3706 - 3718
• Main Authors: Zhou, Jia-Xing, Zhou, Yu-Jun, Zhang, Jian, Dong, Yan, Liu, Fen-Wu, Wu, Zhi-Hui, Bi, Wen-Long, Qin, Jun-Mei
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 28.10.2022; Taylor & Francis Ltd
• Subjects: Arsenic; Arsenic removal; Biogenic schwertmannite; Chemical precipitation; Goethite; Groundwater; Groundwater treatment; Minerals; pH effects; Pollutant removal; Specific surface; specific surface area; Surface area; Synthesis; total Fe precipitation; pH; specific surface area; As; total Fe precipitation; biogenic schwertmannite
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2021.1933200

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 m 2 /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 m 2 /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.