Reconstitution of dewatered food processing residuals with manure to increase energy production from anaerobic digestion

A potentially effective wastewater treatment strategy for a food processor is to concentrate high carbon solid wastes by segregation and dewatering of bulk flow. This solid-liquid separation process results in a weaker wastewater fraction that can be economically disposed to sewer or potentially land applied with minimum surcharge, while remaining solids are collected and applied to landfill. An alternative to the landfill is to anaerobically digest the waste. This technology involves the degradation of organic matter in the absence of free oxygen. A byproduct is biogas that contains a substantial amount of methane which can be used to generate energy.;The following study evaluates the reconstitution of dewatered food processing waste with manure to gain increases in energy produced per unit volume in a farm digester, and thereby increase profitability for the farmer. Two batch digestion studies were conducted on different blends of food waste and manure to determine if a synergistic relationship existed in gas production. A further semi-continuous study provided a more realistic interpretation of real-life co-digestion. Although gas production appeared additive in the batch studies, the semi-continuous digestion of an optimized food waste and manure blend was found to produce over twice as much methane as manure digested alone in reactors of same working volume.