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

Table 5

Kinetic parameters obtained from the exponential 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)	(days^−1)
Untreated OMSW	197 ± 4	0.82 ± 0.06	0.97	11.3
20	158 ± 7	1.21 ± 0.14	0.94	5.2
90	191 ± 11	0.83 ± 0.17	0.92	12.2
180	199 ±10	0.83 ± 0.16	0.93	7.7

is the ultimate methane production; is the specific rate constant or apparent kinetic constant. Parameters from the nonlinear regression fit: : coefficient of determination; S.E.E.: standard error of estimate.