Role of pretreatment and evidence for the enhanced biodegradation and mineralization of low-density polyethylene films by greater waxworm
The present study reports the role of pretreatment for the enhanced biodegradation of low-density polyethylene (LDPE) with Galleria mellonella (Greater waxworm). The pretreatment of the LDPE film was carried out under solar radiation. The pretreated LDPE (PTLDPE) and untreated LDPE (UTLDPE) were characterized with AFM, FTIR and 1H NMR techniques. The qualitative analysis for the biodegradation of pretreated and untreated LDPE was examined by analysing the Excreta residue (ER) of Galleria mellonella fed with LDPE. The mineralization of the ER of waxworm fed on Waxcomb (WC), UTLDPE and PTLDPE were studied by analysing the changes in physiochemical properties through FTIR, 1H NMR and GC-MS techniques in addition to weight loss percentage of PTLDPE and survival rates of the tested greater waxworms. Solar pretreatment of LDPE led to increased surface roughness which favoured the waxworms to feed voraciously on PTLDPE. The post degradation studies of Waxcomb (WC), PTLDPE and UTLDPE showed 92.03 ± 2.1%, 18.57 ± 1.8% and 55.8 ± 1.2% weight loss, respectively. The FTIR, 1H NMR and GC-MS results confirm that the ER of waxworm fed on WC, UTLDPE and PTLDPE showed the presence of new carbonyl and alcoholic groups with increase in unsaturated hydrocarbon indicating enhanced mineralization of LDPE. The efficient mineralization of PTLDPE by waxworm was observed without affecting its survivability. A plausible mechanism of LDPE degradation has also been proposed. The rapid and cost effective biodegradation of PTLDPE through waxworm paves a new and facile route for hazardous plastic waste treatment.