at a flow rate of 400 L/hr. During cessation of aeration
and then after resumption of aeration, oxygen amount
was measured every minute according to the protocol of
Leveaux and Bouix (1988), allowing the determination of
the KLa values, which were 0.236 and 0.233 min−1 for the
two ceramic air sprinklers of 150 mm length and for the
plane sprinkler of 250 mm length respectively. Since close
KLa values were found, the plane sprinklers were chosen
for their higher length and their easiness to be implemented
in the tank (plane sprinklers).
The results recorded in the pilot tank (110 L) (Fig. 4)
were similar to those recorded at lab-scale (Fig. 2) showing
an absence of volume effect on the biodegradation of the
organic matter, which appeared promising for a subsequent
extrapolation at industrial scale (biological tank of the
wastewater treatment plant).
The increase of the total COD recorded during the first
day of culture showed the transfer of non-soluble to soluble
COD, leading to more biodegradable molecules, available
for growth of activated sludge found in the biological tank