Track: Energy
Abstract
The potential to recover biogas and bio solids from piggery sludge was investigated as a waste management technique. Three 1L bio digesters were loaded with piggery slurry and anaerobic digestion took place over a period of 35 days under mesophilic conditions of 35 ±1 ◦C. The piggery sludge properties which included pH, total solids (TS), chemical oxygen demand (COD), biogas and bio solids compositions were measured using standard techniques. MATLAB R2013a was used for determination of the linear models for changes in COD, TS, pH and amount of biogas generated at 95% confidence interval. The R2 and the SSE were used to determine the accuracy of the derived models. As the digestion period increased the sludge total solids content and chemical oxygen demand decreased by 80% and 90% respectively. Cumulative biogas of approximately 4 L/day was achieved with a peak at 30 days. The biogas produced had a methane composition of 65%. Accurate models with R2 values of >0.9 can be used to determine the changes in the given parameters during biogas production. Anaerobic digestate was harnessed with an average of 4.2% nitrogen, 0.5% phosphorous and 4.7% potassium.