Improvement of methanogenesis from cow dung and poultry litter waste digesters by addition of iron

When 50mM FeSO₄ was added to cow dung and poultry litter waste which had been processed in daily-fed batch digesters, digesters subsequently unfed showed a faster conversion of substrate and overloaded digesters stabilized within 48 h. Early stabilization of digesters was achieved by adding 20 or 50mM FeSO₄ though the latter concentration was faster. When 20mM FeSO₄ was added to the daily-fed cow dung and poultry litter waste digesters, it increased methanogenesis by 40% and 42%, respectively, and increased the turnover rate of total solids, volatile solids and volatile fatty acids and the number of methanogens.The authors are with the Department of Microbiology, Osmania University, Hyderabad-500007, India