Long-term bioremediation of cadmium contaminated sediment using sulfate reducing bacteria: Perspective on different depths of the sediment profile

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2023-01, Vol.451, p.138697, Article 138697
• Main Authors: Zhao, Qing, Li, Xiaomin, Wang, Ying, Cheng, Yinghao, Fan, Wenhong
• Format: Article
• Language: English
• Subjects: Column reactor; Heavy metal; In-situ remediation; Sediment profile; Sulfate reducing bacteria
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.138697

•The Cd remediation performance of SRB varied across the sediment profile.•Surface sediment (0–6 cm) was the main remediation range with SRB bioremediation.•SRB bioremediation can inhibit Cd release and bioavailability within the sediment.•The relationship between labile S2- and Cd indicates the remediation performance.•Cd speciation in the sediment was the main factor affecting Cd bioavailability. Sulfate reducing bacteria (SRB) can be utilized for the in-situ remediation of heavy metal contaminated sediment, and the remediation processes occurring at different depths of the sediment profile are critical to the practical application of SRB. In this study, column reactors with sediment profile sampling devices were designed to investigate the variations in Cd speciation, labile S2− and microbial community at different depths of the sediment profile during the bioremediation of Cd contaminated sediment by SRB, over a 270 day monitoring period. In order to evaluate the remediation effect, in vitro extraction of sediment was performed with Sipunculus nudus intestinal juice to determine Cd bioavailability. Results showed that bioremediation caused acid soluble Cd to decrease in the surface sediment (0–6 cm), while reducible and residual fractions of Cd increased. The bioavailability of Cd in the surface sediment reduced by 25.1 % compared to before bioremediation, while no significant changes were observed in other sediment layers. These results indicate that the surface sediment was the main remediation range when SRB were initially added at the water–sediment interface. Furthermore, labile Cd and S2− in the surface sediment of the bioremediation column reactor exhibited a negative correlation (P