Diversity of thermophilic populations during thermophilic aerobic digestion of potato peel slurry.
OBJECTIVE
To study the diversity of thermophiles during thermophilic aerobic digestion (TAD) of agro-food waste slurries under conditions similar to full-scale processes.


RESULTS
Population diversity and development in TAD were studied by standard microbiological techniques and the processes monitored by standard fermentation procedures. Facultative thermophiles were identified as Bacillus coagulans and B. licheniformis, while obligate thermophiles were identified as B. stearothermophilus. They developed rapidly to peaks of 10(7) to 10(8) in <or=48 h. Stability of obligate thermophiles increased with process temperatures. Thermophiles were unstable at process pH above or below neutral, but developed rapidly at all aeration rates. Peak populations were higher in the median than at extremes of aeration rates. Obligate thermophiles were unstable at low aeration rates. Process self-heating was higher at lower than at higher aeration rate. Beyond 96 h most thermophiles were present as spores.


CONCLUSIONS
Limited range of indigenous thermophiles drives TAD of slurry. They develop rapidly and are stable at most digestion conditions.


CONCLUSIONS
Development and stability of thermophiles in TAD suggest that the process may be operated in a wide range of conditions; and even at short HRT in continuous processes without compromising efficiency.
Ugwuanyi
J O
JO
Strathclyde Fermentation Centre, University of Strathclyde, Glasgow, UK. jerryugwuanyi@yahoo.com
Harvey
L M
LM
McNeil
B
B
D001420:Bacteria, Aerobic / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology; D004063:Digestion; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology; D012722:Sewage / Q000382:microbiology*; D011198:Solanum tuberosum; D013171:Spores, Bacterial; D014865:Waste Disposal, Fluid
D012722:Sewage