Abstract: An experiment was carried out to explore effects of pretreatment of food waste with alkali at 80℃ for 30 minutes on production, concentration and composition of volatile fatty(VFA) in the food waste under single phase anaerobic fermentation at 35℃as affected by pH in the pretreatment. The experiment was designed to have five pH treatments, i.e. 8.0, 9.0, 10.0, 11.0 and 12.0. Results show that pH in the pretreatment significantly affected concentration and composition of the VFA produced in food waste under anaerobic fermentation. The content of total VFA, propionic acid and butyric acid in Treatments 10.0, 11.0 and 12.0, was higher than their respective ones in Treatments 8.0 and 9.0. During the 120 hours of anaerobic fermentation, contents of acetic acid and butyric acid are evidetly higher than contents of pentanoic acid in terms of proportion in composition for all treatments; and the sum of acetic acid and butyric acid accounted for 62.02%-82.08% of the total VFA, indicating a typical butyric acid-type fermentation. VFA concentration was the highest in Treatment 11.0, reaching up to 60.14 g?L^-1 at the end of the 120-hour anaerobic fermentation and being 6.14%-48.45% higher than that in the other 4 treatments. Obviously pH 11.0 is the optimal one for thermo alkaline pretreatment of food waste for VFA production via anaerobic fermentation.

Key words: thermal alkaline pretreatment, food waste, anaerobic fermentation, volatile fatty acid (VFA)