Waste management, energy generation, and agricultural production are all resource intensive sectors of the human economy that are usually associated with negative environmental consequences. Integrated management provides opportunities for improving the efficiency of these sectors by using wastes from each as a resource for another; i.e. food waste used as feedstock for energy generation yields byproducts that serve as fertilizer for agricultural production. We propose a model for integrated management based on principles of ecosystem dynamics where humans serve a manipulative, but functional, role in energy transfer and nutrient cycling that results in lower environmental impacts than conventional management. A prototype system for integrated waste, energy, and agriculture was established in 2015 to co-produce biomass (perennial and annual grasses grown on abandoned agricultural land) and biogas (produced through anaerobic digestion) using only food waste and rainwater as inputs.
Results/Conclusions
Dry biomass yields of Sorghum bicolor grown with digestate fertilizer were not significantly different from yields of the same variety grown with conventional fertilizers (p > 0.05). Energy yields from biogas production varied with food waste composition, and large increases in fuel production were observed when food waste contained large proportions of meat and carbohydrates. Food waste collected at a rate of 6 tons per day is estimated to produce less than one fourth of the energy demands of the community from which the waste was sourced, but secondary benefits include reduced energy demand for agricultural inputs and waste disposal.