Waste to wealth in a slaughterhouse through effective biomass management

This study presents a classic case of realizing wealth from waste through effective biomass management in two slaughterhouses having a slaughtering capacity of 1000 buffalos per day. On average, 32 to 35 tonnes of dung solids per day, either partially or fully digested, were recovered from the lairage (where animals are retained before slaughtering) and paunch sections (where intestinal contents are removed after slaughtering), respectively. The recovered dung solids with average moisture content (MC) of 85 % were dewatered using a screw press and dried up to <= 10% MC with a rotary sludge dryer. Then, briquettes were manufactured without using any binder. Fourier-transform infrared spectroscopy (FTIR) and UV-auto-fluorescence (UV-AF) studies revealed the binding mechanism of dung solids was due to the presence of lignin. Furthermore, owing to the presence of cellulose, hemicellulose, and lignin, the finished biomass briquette's calorific value was observed to be 3032 Kcal/kg. The manufactured briquettes' heavy metals concentration was lower than the briquettes derived from wood waste and vine shoots. The toxicity characteristics leachability procedure (TCLP) and waste extraction test (WET) analysis showed that the ash produced after the briquettes' combustion is safe for disposal/landfilling. The emission of vent gases such as CO, CO2, SO2, and NOx was lower than wood chips and forest waste. The full-scale demonstration of dung management using dewatering, drying, and briquetting system offers a net profit of Rs. 1,560,000 (21,016 USD) annually. The proposed system has huge potential for replication in livestock/dairy farms for dung management.