Continuous fermentation of food waste leachate for the production of volatile fatty acids and potential as a denitrification carbon source

Abstract

This study investigated the simultaneous effects of hydraulic retention time (HRT) and pH on the continuous production of VFAs from food waste leachate using response surface analysis. The response surface approximations (R2 = 0.895, p < 0.05) revealed that pH has a dominant effect on the specific VFA production (PTVFA) within the explored space (1–4-day HRT, pH 4.5–6.5). The estimated maximum PTVFA was 0.26 g total VFAs/g CODf at 2.14-day HRT and pH 6.44, and the approximation was experimentally validated by running triplicate reactors under the estimated optimum conditions. The mixture of the filtrates recovered from these reactors was tested as a denitrification carbon source and demonstrated superior performance in terms of reaction rate and lag length relative to other chemicals, including acetate and methanol. The overall results provide helpful information for better design and control of continuous fermentation for producing waste-derived VFAs, an alternative carbon source for denitrification.