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Selective production of volatile fatty acids at different pH in an anaerobic membrane bioreactor

Khan, Mohd Atiqueuzzaman, Ngo, Huu Hao, Guo, Wenshan, Chang, Soon Woong, Nguyen, Dinh Duc, Varjani, Sunita, Liu, Yi, Deng, Lijuan, Cheng, Chen
Bioresource technology 2019 v.283 pp. 120-128
chemical oxygen demand, fouling, isobutyric acid, membrane bioreactors, methane production, pH, propionic acid, volatile fatty acids, wastewater
This study investigated the production of major volatile fatty acid (VFA) components in an anaerobic membrane bioreactor (AnMBR) to treat low-strength synthetic wastewater. No selective inhibition was applied for methane production and solvent-extraction method was used for VFA extraction. The results showed acetic and propionic acid were the predominant VFA components at pH 7.0 and 6.0 with concentrations of 1.444 ± 0.051 and 0.516 ± 0.032 mili-mol/l respectively. At pH 12.0 isobutyric acid was the major VFA component with a highest concentration of 0.712 ± 0.008 mili-mol/l. The highest VFA yield was 48.74 ± 1.5 mg VFA/100 mg CODfeed at pH 7.0. At different pH, AnMBR performance was evaluated in terms of COD, nutrient removal and membrane fouling rate. It was observed that the membrane fouled at a faster rate in both acidic and alkaline pH conditions, the slowest rate in membrane fouling was observed at pH 7.0.