FIG. 4.

Temperature characteristics of mesophilic biomass (20 times diluted) exposed for a prolonged period of time to psychrophilic conditions. ○, methane production rate (grams of COD per liter per day); ◊, propionate degradation rate (grams of COD per liter per day); ●, acetate accumulation rate (grams of COD per liter per day). The lines were computed by using the Arrhenius model for the methane production rate (solid line) and the square root model for the propionate degradation rate (dashed line).