Arsenite removal without thioarsenite formation in a sulfidogenic system driven by sulfur reducing bacteria under acidic conditions. (15th March 2019)

• Record Type: Journal Article
• Authors: Sun, Jianliang; Hong, Yaowu; Guo, Jiahua; Yang, Jierui; Huang, Duanyi; Lin, Zichao; Jiang, Feng
• Is Part Of: Water research. Volume 151(2019)
• Page Start: 362
• Page End: 370
• Publication Date: 2019-03-15
• Subjects: Sulfidogenic process -- Wastewater treatment -- Sulfur reducing bacteria -- Acid mine drainage -- Arsenic removal -- Thioarsenite; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.12.027
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Sulfidogenic process using sulfate-reducing bacteria (SRB) has been used to remove arsenite from the arsenic-contaminated waters through the precipitation of arsenite with sulfide. However, excessive sulfide production and significant pH increase induced by sulfate reduction result in the formation of the mobile thioarsenite by-products and the inefficiency and instability of arsenite removal, especially when the arsenite level fluctuates. In this study, we proposed a novel sulfidogenic process driven by sulfur reducing bacteria (S 0 RB) for the arsenite removal under acidic conditions. In a long term experiment, efficient sulfide production (0.42 ± 0.2 kg S/m 3 -d) was achieved without changing the acidic condition (pH around 4.3) in a sulfur reduction bio-reactor. With the acidic sulfide-containing effluents from the bio-reactor, over 99% of arsenite (10 mg As/L) in the arsenic-contaminated water was precipitated without the formation of soluble thioarsenite by-products, even in the presence of excessive sulfide. Maintaining the acidic condition (pH around 4.3) of the sulfide-containing effluent was essential to ensure the efficient arsenite precipitation and minimize the formation of thioarsenite by-products when the arsenite to sulfide molar ratios ranged from 0.1 to 0.46. An acid-tolerant S 0 RB, Desulfurella, was found to be responsible for the efficient dissimilatory sulfur reduction under acidic conditions without changing the solution pH significantly. The microbial sulfur reduction may proceed through the direct electron transfer between the S 0 RB and sulfur particles, and also through the indirect electron transport mediated by electron carriers. The findings of this study demonstrate that the proposed sulfidogenic process driven by S 0 RB working under acidic conditions can be a promising alternative to the SRB-based process for arsenite removal from the arsenic-contaminated waters. Graphical abstract: Image 1 Highlights: Efficient sulfide production by sulfur reducing bacteria (S 0 RB) was achieved at pH ∼4.3. The pH increase during the microbial sulfur reduction was insignificant. Arsenite was efficiently precipitated by sulfide at varied As/S molar ratios. Maintaining acidic conditions is essential to minimize the thioarsenite formation.