Anaerobic digestion of biodegradable plastics: analysis in terms of process conditions and overall performance

In the present study commercial Polylactic Acid-based disposable cups and plates available on the market were selected for lab scale anaerobic degradability tests. The experiments were carried out under mesophilic and thermophilic conditions at different food to microorganisms (F/M) ratios and test material size, and the specific biogas production and associated kinetics were evaluated. Maximum biogas production was comparable for almost all the experimental runs and only test material size reduction appeared to result in higher yields. Temperature increase influenced particularly the biodegradation degree, ranging between 93 and 100% for thermophilic runs, and the process kinetics resulting in a reduction of residence time by 70%. The specific methane yield ranged from 455 to 545 Nml/gVSfood and from 430 to 505 Nml/gVSfood under mesophilic and thermophilic conditions respectively