FUNDAMENTAL-STUDIES ON HYDROGEN-PRODUCTION IN THE ACID-FORMING PHASE AND ITS BACTERIA IN ANAEROBIC TREATMENT PROCESSES - THE EFFECTS OF SOLIDS RETENTION TIME

Effects of solids retention time (SRT) on hydrogen gas production, glucose degradation and anaerobic bacteria in anaerobic treatment processes were investigated with use of 11,700 mg/l glucose solution as a substrate. Five series of experiments were conducted at 36 +/- 1-degrees-C. Volatile fatty acids were produced in the order: acetic, n-butyric, propionic and n-valeric with concentration of effluent. Counts of general anaerobic bacteria and acid-forming bacteria in each reactor increased with increasing SRT, and counts of genus Clostridium and sulphate reducing bacteria in the reactor decreased with increasing SRT of the reactor, Gas production rates and gas composition were investigated to obtain information on energy production. Solids retention time increased from 2 to 10 h, hydrogen gas content decreased from 12 to 9%. The kinetic constants such as the microbial decay coefficient (K(d)), the maintenance coefficient (m) and the growth yield for microorganisms (Y(G)) were 4.04, 41.7 and 0.097 day-1, respectively.