2.6. Effect of nitrogen sources on biogas production
To evaluate the effect of nitrogen sources on digester performance, conical flasks containing 100 g of feedstock were mixed with different quantities of poultry droppings or urea fertilizer as indicated below. Digester containing 100 g of RH without poultry droppings or urea served as a control. Using different digesters, 100 g of RH was mixed with 25 g of poultry droppings or urea to give feed to poultry droppings/urea ratios of 4:1 (w/w). To initiate fermentation, each of the flasks was inoculated with 50 mL of freshly strained cow rumen liquor and 300 mL of water was added. Incubation was done at 30 °C for hydraulic retention time (HRT) of 28 days