Comparison of thermal alkaline pretreatment and zinc acetate-catalyzed methanolysis (MtOH-ZnOAc) for anaerobic digestion of bioplastic waste

[Display omitted] •Performing MtOH-ZnOAc and NaOH in bioplastic pretreatment and biogas production.•Pretreated bioplastic biogas production in mesophilic and thermophilic conditions.•Dilution of pretreated bioplastic affects biohydrogen and biomethane production.•The two-stage system performed better than a mono-stage system.•Predominant Methanosaetaceae positively correlated with the biogas production rate. The aim of this work was to study the effect of thermal alkaline pretreatment and zinc acetate-catalyzed methanolysis (MtOH-ZnOAc) in biogas production from bioplastic in anaerobic digestion. The pretreated bioplastic with MtOH-ZnOAc performs efficient solubilization and produced 205.7 ± 6.9 mL/g CODadded, which is higher than thermal alkaline degradation. The mesophilic condition produces more than 79% higher biogas compared with the thermophilic condition with the diluted pretreated bioplastic by 30 times. The kinetic study was well fit the experimental data and showed the correlation between cumulative biogas, production rate, and lag phase with mono- and two-stage system in batch fermentation. The two-stage system produced 315.6 ± 7.7 mL/g CODadded which was higher 67.2 ± 2.02 than the mono-stage system. Methanosaetaceae predominates among the Archaea, which are primarily responsible for methanogenesis, showing a contribution to a higher biogas production rate.