What are the conditions in fermenter?
Cellulose degradation to methane under continuous fermentation conditions was compared using Cellulose degradation to methane under continuous fermentation conditions was compared using fully mixed, fully mixed with solids return, sludge-blanket, and fixed-film fermenters.^In fully mixed fermenters, a decrease in hydraulic retention time (HRT) of two weeks or less caused the washout of anaerobes capable of converting volatile fatty acids to methane, while at increased feeding rates over 1 g/L day the rapid growth of cellulolytic anaerobes upset the balance between acid formation and its conversion to methane.^Circulation of cellulose and difficulty in settling of cellulose with attached bacteria imposed problems in the use of other types of fermenters.^On the basis of information obtained from this study, a fermenter which combined a fully mixed phase for cellulose degradation and a fixed-film phase with preimmobilized bacteria for converting fatty acids to methane in one vessel was de
