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

Table 3

Characteristics of the two-phase OMSW used (80% w/w) after different ultrasound pretreatment times and without pretreatment.

Time	Moisture	TS	VS	CODt	CODs	Solubilization
(min)	(%)	(g/kg)	(g/kg)	(g O2/kg)	(g O2/kg)	(%)
Untreated OMSW	78.8 ± 0.2	212.0 ± 2.6	182.7 ± 2.3	265.4 ± 0.7	114.7 ± 3.2	43
20	79.9 ± 0.2	206.4 ± 0.2	177.7 ± 1.9	331.3 ± 1.0	148.3 ± 0.2	56
40	80.8 ± 0.1	191.8 ± 0.9	164.1 ± 0.2	331.4 ± 0.0	130.9 ± 0.0	49
60	78.6 ± 0.4	213.8 ± 3.6	181.4 ± 5	376.6 ± 0.4	146.8 ± 0.0	55
90	78.3 ± 0.3	217.3 ± 2.9	183.8 ± 0.0	370.0 ± 0.1	151.0 ± 0.0	57
120	79.3 ± 0.3	206.8 ± 3.2	173.3 ± 0.0	385.2 ± 0.6	150.6 ± 0.1	57
180	77.9 ± 0.5	221.4 ± 5	188.6 ± 7.4	377.5 ± 0.0	126.1 ± 0.0	48

TS: total solids; VS: volatile solids; CODt: total chemical oxygen demand; CODs: soluble chemical oxygen demand.