Biodegradation Study on Conventional Plastics Using Single-Stage Anaerobic Digestion

This study investigated the anaerobic biodegradation potential of conventional plastics. A single-stage laboratory-scale anaerobic digester was fed with a mixture of conventional plastics and high-solids anaerobic sludge from an industrial UASB reactor. The plastics investigated included polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC). It was observed that only PVC, HDPE, and PET biodegraded under mesophilic anaerobic conditions. The biodegradation rate varied based on the type of plastic, with PVC being the most biodegradable (11.6% after 250 days) and HDPE being the least biodegradable (3.1% after 250 days). LDPE, PS, and PP showed no biodegradation even after 250 days, and scanning electron microscopy (SEM) analysis showed no evidence of biodegradation for these plastics. Overall, the study showed that anaerobic digestion is not as effective for the biodegradation of conventional plastics as it is for bioplastics, although PVC, PET, and HDPE exhibited certain extent of biodegradation. Further research is needed to optimize the process and develop more efficient microbial strains for biodegradation of plastics.