Effect of Ultrasonic Pretreatment on Biomethane Potential of Two-Phase Olive Mill Solid Waste: Kinetic Approach and Process Performance

Table 6

Kinetic parameters obtained from the logistic model in the BMP tests of untreated OMSW and ultrasound pretreated OMSW at 20, 90, and 180 min.

Time						S.E.E.
(min)	(mL CH4/g VSadded)	(mL CH4/g VSadded)	(mL CH4/g VS·d)	(days)
Untreated OMSW	198 ± 4	171 ± 4	62.7	9.4 ± 0.1	0.99	3.4
20	160 ± 5	130 ± 55	64.4	6.3 ± 0.8	0.96	7.6
90	187 ± 9	200 ± 9	70.5	7.9 ± 0.2	0.99	5.3
180	193 ± 8	174 ± 8	63.9	7.7 ± 0.2	0.99	2.1

is the cumulative methane production at the startup of the second stage, is the maximum methane production obtained in the second stage, is the maximum methane production rate, and is the lag time. Parameters from the nonlinear regression fit: : coefficient of determination; S.E.E.: standard error of estimate.