Effects of alkalinity sources on the stability of anaerobic digestion from food waste

Abstract

This study investigated the effects of some alkalinity sources on the stability of anaerobic digestion (AD) from food waste (FW). Four alkalinity sources, namely lime mud from papermaking (LMP), waste eggshell (WES), CaCO3 and NaHCO3, were applied as buffer materials and their stability effects were evaluated in batch AD. The results showed that LMP and CaCO3 had more remarkable effects than NaHCO3 and WES on FW stabilization. The methane yields were 120.2, 197.0, 156.2, 251.0 and 194.8 ml g−1 VS for the control and synergistic digestions of CaCO3, NaHCO3, LMP and WES added into FW, respectively. The corresponding final alkalinity reached 5906, 7307, 9504, 7820 and 6782 mg l−1, while the final acidities were determined to be 501, 200, 50, 350 and 250 mg l−1, respectively. This indicated that the synergism between alkalinity and inorganic micronutrients from different alkalinity sources played an important role in the process stability of AD from FW.