Proteinase K impact on anaerobic co-digestion of modified biodegradable plastic and food waste: Step-by-step analysis with microorganism

Abstract

This study was designed to explore the key impact of Proteinase K (PK) on every step of anaerobic co-digestion. The results of step-by-step experiments indicated that PK promoted the hydrolysis of biodegradable plastic by initiating self-hydrolysis reactions, directly promoting the hydrolysis step of anaerobic co-digestion. Subsequently, PK indirectly promoted the acidogenesis and acetogenesis steps by impacting the proliferation of acid-producing bacteria. Besides, it could also hydrolyze PLA. Thus, the lactic acid content peaked at 255.7 mg/L on the 5th day, representing an increase of 35.9 % compared to the condition without PK. Finally, PK indirectly promoted the methanogenesis step through its impact on the composition of methanogenic bacteria. This led to more food waste being digested into methane, 41.5 % compared to the condition without PK. This work served as an essential foundation for advancing the application of PK modified BP as a replacement for traditional plastics.