Chemical characterization of anaerobic digestion treatment of poultry mortalities

Abstract

Proper disposal of poultry mortalities is of major concern for the poultry industry. A preliminary investigation was conducted to evaluate an anaerobic digestion system as an alternative for poultry mortality disposal. The system consisted of a leachbed (LB) and an upflow anaerobic sludge blanket (UASB), connected in a closed loop. The LB served as the hydrolysis/acidification phase, while the UASB served as the methanogenesis phase. Effluent from the LB served as influent to the UASB while effluent from the UASB overflowed to the LB to continuously inoculate the LB with methanogens. Three experiments were conducted, two at 55 °C and one at 35 °C. In one of the 55 °C experiments, different moisture contents in the LB were tested to evaluate the rate and extent of digestion of the mortalities. Higher initial moisture content in the LB was beneficial to methane production. The mortality was solubilized quickly and converted into a very concentrated effluent. The UASB was able to generate methane efficiently at loading rates below 2g COD L −1 day −1. The UASB at 55 °C performed poorly when the loading rate exceeded 2g COD L −1 day −1. Digestion at 35 °C looks promising. However, the process needs to be optimized to be competitive with other biological disposal alternatives.