Algal deterioration of PET (polyethylene terephthalate) plastic bottle in combination with physical and chemical pretreatments: A macrocosm study

Abstract

Plastic pollution has become an environmental issue worldwide because of its slow degradation and persistent nature. Many traditional methods exist and are practiced here to handle and reuse plastic waste, but those need to be more capable of tackling increasing waste volume. Biological plastic waste management could be a sustainable way to ensure environmental quality. Therefore, this study aimed to screen the bio-deterioration of PET wastes using physical and chemical pretreatments. We kept PET samples in freshwater and marine water media designed to support algal growth and incubated those under direct or indirect sunlight or in dark conditions. We observed algal growth and measured deterioration of PET samples using the tensile strength test, FTIR, and viewed surface properties using FESEM. Acid pretreatment and exposure to direct sunlight left the PET most fragile. FTIR analysis also supported the observation, and changes in functional groups are evident. Heat pretreatment usually reduces the volume and thus increases strength. Bottles incubated under direct or indirect sunlight supported the algal growth. The most prevalent algal species found in freshwater environments include Volvox, Chlorella vulgaris, Craticula cuspidate, Navicula pupula, Synedra ulna, and marine environments include Palisada perforate, Ulva flexuosa, Cladoptera herpestica, and Blindingia minima. Algal growth increases the porosity and surface cracks of PET bottles. Though FTIR analysis did not show any change in functional groups, except for acid pretreatment, upon algal growth, the transmittance increase indicated decay of PET samples.