Investigating the Anaerobic Co-Digestion of Food Waste at the Prairie View A & M University Campus Dining Facility
Abstract: The United States Department of Agriculture reports that in 2010, approximately 133 billion pounds and $161 billion worth of food were wasted in the United States. Food Waste (FW) is currently handled through municipal disposal and can be a valuable resource to obtain renewable methane. Typical characteristics that affect biochemical methane potential of FW are carbohydrates, proteins, lipids and cellulose, which could increase the accumulation of volatile fatty acids (VFA) and ammonium nitrogen during anaerobic digestion (AD). This study investigates AD of FW in combination with goat manure and cotton-gin trash to produce methane. The chemical characteristics of FW at the Prairie View A & M University campus dining facility were determined to serve as baseline measurements for designing an AD system. Due to the daily menu changes at the dining facility, FW samples were collected Monday-Thursday in order to determine the statistical variability for each chemical constituent. The chemical characteristics that were examined include: Water/Moisture Content (post-dilution) (%), pH, Chemical Oxygen Demand (COD, g/L), Alkalinity (mg/L), Total Solids (%), Volatile Solids (%), and Nitrogen-Ammonia (mg/L NH3-N). Elemental characterization of FW was performed using Elementar Vario Macro Cube CNHS combustion elemental analyzer, to determine the Carbon (%), Nitrogen (%), Hydrogen (%) and Sulphur (%). On average, the chemical characteristics were determined as: MC: 93.4%, pH: 6.0, COD: 132.9 g/L, Alkalinity: 1.6 g/L, TS: 7.3%, VS: 95.3%. The elemental analyses were determined to be: N: 7.6%, C: 52.4%, H: 8.0%, and S: 0.3% with a C/N ratio of 6.88. The low value of C/N ratio suggests that FW by itself would not be able to provide enough organic matter for microbial growth and sustained methane production. This indicates that FW can only be co-digested with high organic wastes such as manure for effective AD operation.
De Jaune’ C. Bickham*
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