Effect of pH Shock and H2S Inhibition on the Competition between Methane Production and Sulfate Reduction in a UASB Reactor

• Published in: Journal of Japan Society on Water Environment Vol. 38; no. 1; pp. 1 - 8
• Main Authors: HU, Yong, SUDO, Yuta, NIU, Qigui, HOJO, Toshimasa, LI, Yu-You
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo Japan Society on Water Environment 2015; Japan Science and Technology Agency
• Subjects: Aeration; Archaea; Bacteria; Biological competition; Cloning; Competition; Ethanol; H2S inhibition; Hydrogen sulfide; Load distribution; Loading rate; Methane; Methane production; Organic loading; Oxidation; pH; pH effects; pH shock; Reactors; Reduction; rRNA 16S; Sludge; Sulfate reduction; Sulfate-reducing bacteria; Sulfates; Sulphate reduction; Sulphides; UASB; Upflow anaerobic sludge blanket reactors; Wastewater; Wastewater treatment
• ISSN: 0916-8958; 1881-3690
• DOI: 10.2965/jswe.38.1

To investigate the effect of oxygen, pH shock, and H2S inhibition on the competition between methane-producing archaea (MPA) and sulfate-reducing bacteria (SRB), a UASB reactor treating sulfate-rich wastewater was operated for 360 days. With micro-aeration in the upper part of the upflow anaerobic sludge blanket (UASB) reactor, sulfate removal increased from 45.0% to 68.6%. However, methane production was still the main reaction in the reactor. In addition, following the influence of pH shock and the organic loading rate, the free sulfide concentration increased to more than 200 mg·L-1 owing to the enhanced sulfate reduction. As a result, the methane production was completely inhibited, which indicated that the free sulfide concentration seriously affected the MPA. The UASB performance and 16S rRNA cloning and sequencing results proved that in the complete sulfate-reducing stage, ethanol was mainly utilized by incomplete-oxidizing SRB for sulfate reduction.