Volatile fatty acids production from kitchen waste slurry using anaerobic membrane bioreactor via alkaline fermentation with high salinity: Evaluation on process performance and microbial succession

In this study, a pilot-scale anaerobic membrane bioreactor (AnMBR) was developed to continuously produce volatile fatty acids (VFAs) from kitchen waste slurry at pH 9.0. The alkaline fermentation effectively suppressed methanogenesis, thus achieving a high VFAs production up to 60.34 g/L. Acetic acid, propionic acid and butyric acid accounted for over 95.0% of the total VFAs. The VFAs yield, productivity, and chemical oxygen demand (COD) recovery efficiency respectively reached 0.47 g/g-CODinfluent, 6.03 kg/m3/d and 62.79%. Moreover, the CODVFA/CODeffluent ratio was beyond 96.0%, and the CODVFA/NH3-N ratio through ammonia distillation reached up to 192.49. The microbial community was reshaped during the alkaline fermentation with increasing salinity. The membrane fouling of AnMBR was alleviated by chemical cleaning and sludge discharge, and membrane modules could acquire a sustained filtration performance. In conclusion, this study demonstrated that high-quality VFAs could be efficiently produced from kitchen waste slurry using AnMBR process via alkaline fermentation.