DEGRADATION OF POLYETHYLENE TEREPHTHALATE (PET) AS SECONDARY MICROPLASTICS UNDER THREE DIFFERENT ENVIRONMENTAL CONDITIONS

Abstract

Polyethylene terephthalate (PET) bottles have been widely used as biofilm media for residential-scale Wastewater Treatment Plants (WWTP) in Indonesia because of their advantages such as being inert. PET bottles can also be degraded as secondary microplastic contaminants during the operation of WWTPs. This study aimed to investigate the possibility of degradation of PET as secondary microplastics. The research was carried out in distilled water under three different environmental conditions (indoor laboratory scale, outdoor laboratory scale, and field-scale). The abundance, size, color, and shape of microplastics were observed through a light binocular microscope with a 100x magnification combined with Image Raster 3.0 software. Data of environmental properties (i.e., DO, temperature and pH) were collected. The solubility potential of PET as microplastics was identified after 7 months of indoor and outdoor laboratory experiments with concentrations of 18.67 ± 7.02 MP/L and 44.00 ± 12.77 MP/L, respectively. Experiments on UV irradiation showed faster degradation of PET and the presence of microplastics increased along with the exposure period with concentration at the first month, the second month, the third month, and the seventh month were 15.33 ± 7.09 MP/L, 51.67 ± 9.61 MP/L, 54.33 ± 8.39 MP/L, and 248.67 ± 29.09 MP/L, respectively. The major microplastics characteristics were fragments (92.37%), fiber (7.63%), transparent particle color (82.85%), and particle size of 10 μm (61.04%).