The impact of thermal pretreatment and anaerobic digestion on the degradation of bioplastic bag mixed with food waste.

The market of bioplastics has expanded rapidly in the last decade, and the generation of this new waste stream could create major barriers to waste processing driving the need to define end-of-life alternatives. One application of biodegradable bioplastics are organic waste bags to collect urban food waste (FW), commonly treated in industrial composting. However, the increasing interest to exploit firstly the renewable energy potential of the waste shifted the focus to Anaerobic Digestion (AD) plants to produce biogas from urban waste. Yet, most plastics--whether they are conventional, slightly biodegradable or even certified compostable--are separated at the AD plant and sent to landfill or incineration, raising questions about the merits of a joint collection and processing system for FW and bioplastics bags (BPB). This is because there is currently little understanding of precisely how BPBs biodegrade in an AD setting, especially together with FW (Kakadellis et al., 2022). Aim of this study was to monitor the rate and extent of biodegradation of a common bioplastic bag (made of Mater-Bi® resin) in the anaerobic thermophilic environment together with the collected food waste. Besides, the effect of thermal hydrolysis pre-treatment on BPB characteristics, microscopic appearance and chemical composition before and after AD tests was evaluated, too.