Acetate treatment in 70 degrees C upflow anaerobic sludge-blanket (UASB) reactors: start-up with thermophilic inocula and the kinetics of the UASB sludges.
This study focused on the use the thermophilic anaerobic granulae in the start-up of 70 degrees C acetate-fed upflow anaerobic sludge-blanket (UASB) reactors and the kinetics of granulae grown at 70 degrees C. In the UASB reactors, chemical oxygen demand removal commenced within 48 h of the start-up. The maximum reduction in chemical oxygen demand was 84% with the feed containing yeast and 71% without a yeast supplement. In the bioassays, the yeast-grown sludge converted 98% of the acetate consumed to methane as compared to 92% for the sludge grown without yeast. The highest initial specific methane production rate (mu-CH4) of the UASB sludges grown at 70 degrees C was 0.088 h(-1) at an acetate concentration of 4.6mM. The higher initial acetate concentration was found to prolong the lag-phase in methane production significantly and to decrease mu-CH4. The half-saturation constant (Ks), the inhibition constant (Ki), the inhibition response coefficient (n) and the mu-CH4-max, calculated according to a modified Haldane equation, were 1.5 mM, 2.8 mM, 0.8 and 0.28 h(-1), respectively. The prolonged starvation of the 70 degrees C sludge (15 days) decreased the mu-CH4 from about 0.022 h(-1) to 0.011 h(-1) and increased the lag phase in methane production from 6 h to 24 h as compared with non-starved sludge.
Lepistö
R
R
Institute of Water and Environmental Engineering, Tampere University of Technology, Finland.
Rintala
J A
JA
D000085:Acetates / Q000378:metabolism / Q000494:pharmacology*; D000693:Anaerobiosis; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000295:instrumentation / Q000379:methods*; D007220:Industrial Waste; D007700:Kinetics; D008697:Methane / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D012722:Sewage; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D015003:Yeasts
D000085:Acetates; D007220:Industrial Waste; D012722:Sewage; D008697:Methane; D010100:Oxygen