Enhanced volatile fatty acid production and microbial population analysis in anaerobic treatment of high strength wastewater

Volatile fatty acid (VFA) is the intermediate product of the anaerobic digestion. Generally, the amount of acidogenic and methanogenic microorganisms will affect the output VFA concentration in a wastewater treatment process. In this study, sequencing batch reactor (SBR) was used to enhance VFA production during the anaerobic treatment of palm oil mill effluent. The system managed to suppress the growth of methanogens and increased VFA output by elevating the growth of acidogens. The SBR managed to achieve stable accumulation of VFA throughout the operation. It was found that the VFA produced increased from 7300 mg/L to 10,500 mg/L; however, the VFA composition remains unchanged. The balanced composition of short-chain VFA could be used as the feed for the production of biodegradable polymer. Microbial analysis revealed that methanogens (Methanosaeta, Pseudomonas, and Bacteroides) were eliminated from the system. In addition, VFA-producing bacteria (Lactobacillus, Olsenella, Aeriscardovia, Pseudoramibacter, and Atopobium) were found to be the dominant bacteria in the reactor.