Keywords: polylactic acid, PLA biodegradability, glass transition temperature, municipal landfill, anaerobic biodegradation, aerobic composting, sludge, modelling, municipal solid waste, MSW, waste management
Temperature–dependent polylactic acid (PLA) anaerobic biodegradability
Polylactic acid (PLA) biodegradability is mostly claimed according to PLA biodegradation behaviour under aerobic composting conditions. However, waste materials containing PLA are frequently disposed of in municipal landfills, which are operated anaerobically. PLA anaerobic sludge digestion results are acquired to elucidate effects of the degrading temperature on PLA biodegradation. When the degrading temperature is higher than the PLA glass transition temperature (Tg), anaerobic biodegradation is accelerated. A plausible mechanism to explain this observation is that amorphous part of the polymer is easily accessible by microorganisms. When the degrading temperature is below PLA Tg, anaerobic biodegradation is apparently slowed. PLA anaerobic biodegradation data collected at 50 and 65°C were successfully modelled using the first order kinetic equation.