Combined effect of crude fat content and initial substrate concentration on batch anaerobic digestion characteristics of food waste

The mesophilic anaerobic digestion (AD) characteristics of food waste (FW) with different crude fat (CF) contents and four initial substrate concentrations (4, 6, 8, and 10 gVS/L) were investigated. The maximum methane yields of FW with CF contents of 15%, 20%, 25%, 30%, and 35% were 565.0, 580.2, 606.0, 630.2 and 573.0 mL CH4/gVS(added), respectively. An acidification trend with a drop in pH (<6.80) and increase in the volatile fatty acids/total inorganic carbon (VFAs/TIC) ratio (>0.4) were found for CF contents of 30% (10 gVS/L) and 35% (8 and 10 gVS/L). A 35% CF content in FW led to decrease in the first-order degradation constant of approximately by 40%. The modified Gompertz model showed that the lag phase (lambda) was prolonged from 0.4 to 7.1 days when the CF content in FW and initial substrate concentration were increased to 35% and 10 gVS/L. (C) 2017 Elsevier Ltd. All rights reserved.