Anaerobic treatment of poultry mortality in a temperature-phased leachbed–UASB system

Anaerobic digestion has been proposed as an alternative to the conventional disposal methods of burial, incineration, rendering and aerobic composting. A temperature-phased system consisting of one UASB (at 55 °C) and three leach-bed reactors (at ambient temperatures) was tested for its efficiencies in treating poultry mortality. The thermophilic UASB was difficult to start-up. It also showed signs of inhibited methanogenesis. Chemical parameters such as long chain fatty acids, volatile fatty acids and ammonia concentrations were all very high for the thermophilic UASB. Lowering its temperature to 35 °C enhanced its stability and improved its performances. Lowering the pH of the 55 °C UASB also improved its chemical oxygen demand (COD) reduction efficiency as well as its methane production rate. The results were compared to that of another similar system where the UASB reactor was maintained at 35 °C instead of at 55 °C.