Investigation of anaerobic co-digestion of goat manure for biochemical methane recovery
Abstract: United States department of agriculture (USDA) reports that Texas has the largest number of goats in the nation, at 47% out of the total goat inventory. Large goat population also comes with manure as a by-product from concentrated animal feeding operations (CAFOs). Goat manure could become a source of air pollution by methane and ammonia emissions, and water pollution by nutrient leaching and pathogen contamination of water bodies. This study investigates anaerobic co digestion of goat manure to produce renewable methane and nutrient-rich bio solids as valuable byproducts. Substrate characterization was done by collecting goat manure samples from inside a goat barn at the international goat research center (IGRC) at Prairie View A&M University, and testing for total solids (TS), volatile solids (VS), chemical oxygen demand (COD), pH, alkalinity, moisture contents using standard methods for examination of water/wastewater. Elemental characterization of goat manure was performed with elementar vario macro cube CNHS combustion elemental analyzer to determine carbon, nitrogen, hydrogen and Sulphur in the substrate. Biochemical methane potential (BMP) of the substrate through anaerobic co digestion of goat manure (GM) with food waste (FW) and cotton gin trash (CGT) will be estimated. Results from elemental analysis are Carbon 35.25%, Nitrogen 1.75%, Hydrogen 6.104% and Sulphur 0.512%, with the carbon/nitrogen ratio (C/N) 20: l, in agreement with the optimum C/N ratio range of 15-30. C/N ratio reflects the nutrient levels of the substrate in the digestion system, and a high C/N ratio provides insufficient nitrogen to maintain cell biomass causing lower biogas production. The results for goat manure suggest that there would be sufficient nitrogen in the digestion system for optimum methane recovery. The dry and wet chemical characteristics of the substrate provides an insight into the input parameters to be considered while designing the anaerobic reactor.
Ayobami Orangun*, Venkata S.V. Botlaguduru, Hongbo Du, Raghava R. Kommalapati
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