Evaluation of bioplastics biodegradation under landfill conditions

Abstract

Plastics are utilized in numerous applications due to being applicable and cost-effective. Although their resistance leads to this extensive use, their environmental impacts cannot be ignored. Bioplastics generated mostly from renewable sources are seen as an alternative to conventional plastics. Polylactic Acid (PLA) is one of the mostly produced bioplastics because of its shelf life for various applications. Even though bioplastics have drawn a lot of attention recently, their ultimate situation in landfill sites is still unknown. In this study, standardized laboratory-scale lysimeter experiment was used for the simulation of landfill conditions to evaluate the biodegradability of PLA under real landfill conditions. The reactors were loaded with municipal solid waste taken from an operating landfill, PLA cups and seed sludge. The different phases of landfill stabilization were considered; hence, the reactors were operated under aerobic, semi-aerobic and anaerobic conditions, respectively. Throughout the operation, both the leachate and biogas of the reactors were regularly monitored with regard to their quality and quantity. Bioplastic cups were examined considering their mass change, tactile and visual aspects. The experimental results indicated that bioplastics did not undergo significant biodegradation under the first two phases (aerobic and semi-aerobic) which lasted 106 days. The gravimetric and visual changes were negligible. On the other hand, it was seen that the cups were much softer and whiter after anaerobic phase. The surface of the cups was prominently damaged and there were around 13% decrease in the weight of the cups.