Table 3 Summary of organic fraction municipal solid wastes optimizing pretreatment conditions

Mechanical (Bead milling at 1000 rpm)

OFMSW (Food Wastes)

Batch, 37 °C

Particle size reduction from 0.8 to 0.7 mm improved hydrolysis step and increased methane yields by 28% at 1000 rpm

[34]

Thermal pre-treatment (at 65 °C)

OFMSW, sewage, and leachates

Batch, 37 °C

Thermal pre-treatment at 65 °C accelerated hydrolysis stage and increased biogas yields by 7%

[35]

Thermal pre-treatment (Steam explosion)

OFMSW and citrus wastes

Batch, 55 °C

The steam pretreated citrus wastes co-digested with MSW had a higher methane yield of 0.53 m³ kg⁻¹ VS^− 1 which was 426% higher than the corresponding untreated substrates

[36]

Chemical (5 N NaOH and 5 N KOH at pH 13 and temp 80 °C)

OFMSW (kitchen wastes)

Batch, 35 °C, 90 rpm

The pretreatment of OFMSW with 5 N NaOH and 5 N KOH at a retention time of 10 d increased the solubility of OFMSW and enhanced the biogas increase by 18 and 30% respectively as compared with the untreated OFMSW

[37]

Microbial (wood-rotting fungi)

chestnut and hay leaves

Batch, 37–38 °C

The biogas production was enhanced by 15% as compared to the untreated substrates

[38]

Microbial (white-rot fungi at 60 °C) moisture content)

Yard trimmings

Batch, 37 °C

Pre-treatment of yard-trimmings with Ceriporiopsis subvermispora, white-rot fungi at 60% moisture content enhanced methane production by 106%

[39]