Effect of sulfate on anaerobic reduction of nitrobenzene with acetate or propionate as an electron donor

• Published in: Water research (Oxford) 2012-09, Vol.46 (14), p.4361-4370
• Main Authors: Huang, Jingang, Wen, Yue, Ding, Ning, Xu, Yue, Zhou, Qi
• Format: Article
• Language: English
• Subjects: Acetates; Acetates - chemistry; Anaerobiosis - drug effects; aniline; Applied sciences; Batch Cell Culture Techniques; Biodegradation, Environmental; Biotransformation - drug effects; Electron donor; Electron Transport - drug effects; Equivalence; Exact sciences and technology; hydrogen; Inhibition; Nitrobenzene (NB); Nitrobenzenes; Nitrobenzenes - chemistry; Nitrobenzenes - isolation & purification; Noncompetitive inhibition; Nonlinear Dynamics; Oxygen - metabolism; Pollution; Propionates - chemistry; propionic acid; Reduction; Reductive transformation; Sulfate; Sulfates; Sulfates - chemistry; Sulfates - pharmacology; Thermodynamics; Transformations; Two-stage zero-order kinetics; Waste water; wastewater; Water treatment and pollution
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2012.05.037

Sulfate is frequently found in wastewaters that contain nitrobenzene. To reveal the effect of sulfate on the reductive transformation of nitrobenzene to aniline – with acetate or propionate as potential electron donors in anaerobic systems – an acetate series (R1–R5) and a propionate series (R6–R10) were set up. Each of these was comprised of five laboratory-scale sequence batch reactors. The two series were amended with the same amount of nitrobenzene and electron donor electron equivalents, whereas with increasing sulfate concentrations. Results indicated that the presence of sulfate could depress nitrobenzene reduction. Such depression is linked to the inhibition of nitroreductase activity and/or the shift of electron flow. In the acetate series, although sulfate did not strongly compete with nitrobenzene for electron donors, noncompetitive inhibition of specific nitrobenzene reduction rates by sulfate was observed, with an inhibition constant of 0.40 mM. Propionate, which can produce intermediate H2 as preferred reducing equivalent, is a more effective primary electron donor for nitrobenzene reduction as compared to acetate. In the propionate series, sulfate was found to be a preferential electron acceptor as compared to nitrobenzene, resulting in a quick depletion of propionate and then a likely termination of H2-releasing under higher sulfate concentrations (R9 and R10). In such a situation, nitrobenzene reduction slowed down, occurring two-stage zero-order kinetics. [Display omitted] ► Effects of sulfate on nitrobenzene (NB) reduction were examined. ► Sulfate weakly competed for acetate with NB, but strongly competed for propionate. ► Sulfate noncompetitively inhibited NB reduction in acetate-fed systems. ► Sulfate reduction caused two-stage NB reduction kinetics in propionate-fed systems. ► Depletion of propionate and then a termination of H2-releasing slowed NB reduction.