Operational conditions and natural immobility of cells in the treatment of leftovers by the thermophilic oxic process

The thermophilic oxic process (TOP) is an experimental alternative disposal method of treating several types of organic waste material. Previous research has certified that cedar chips are suitable intermedium for disposing of food leftovers, and that in feeding interval of 24-36 hours, the biodegradation capacity can be raised to 22.77 kgmE-3 dayE-1 by the management of temperature. In this paper, we investigate the influence of different aeration rates, discuss the change of water content in the whole process, and suggest a new view about natural immobility of cells. In addition, we provide results for a batch of experiments conducted to explain the aforementioned conjecture. The following points were derived from this study: (1) The aeration rate had an obvious influence on the disposal of leftovers during TOP: low aeration rate (0.05m**3mE-3minE-1) could not supply enough oxygen. On the other hand, surplus aeration rate (0.15m**3mE-3minE-1) caused heat loss and increased reactor running costs. When the BOD volume load(BVL) was 4.0 kgmE-3 dayE-1, 0.10m**3mE-3minE-1 was a suitable aeration rate; (2) When the BVL was 4.0 kgmE-3 dayE-1 and the aeration rate was 0.10m**3mE-3minE-1, the water content of the intermedium changed from 45.6% to 38.4% while the biodegradation rate was as high as 88.4%; (3) Because bio-heat generated during TOP evaporated the water, the water content stabilized at about 40% in a running reactor. However when feeding was interrupted, the water content decreased to 31.8% after 15 days, remaining there even 60 days later; (4) When feeding supply was resumed, under suitable conditions that aeration rate was 0.10 m**3mE-3 minE-1 and water content was adjusted to 50%, the reactor temperature rose over the room's temperature for 5 deg C after 5 hours and reached to 50 deg C after 26 hours-reactor activity was efficiently revivified.