Investigation of degradation potential of polyethylene microplastics in anaerobic digestion process using cosmetics industry wastewater

• Published in: Biochemical engineering journal Vol. 187; p. 108619
• Main Authors: Akbay, Habibe Elif Gulsen, Akarsu, Ceyhun, Isik, Zelal, Belibagli, Pinar, Dizge, Nadir
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-11-2022
• Subjects: Anaerobic digestion process; Biogas production; Cosmetics industry wastewater; Polyethylene microplastics; Polyethylene microplastics; Biogas production; Anaerobic digestion process; Cosmetics industry wastewater
• ISSN: 1369-703X; 1873-295X
• DOI: 10.1016/j.bej.2022.108619

In this study, the effect of polyethylene (PE) microplastics (MPs) with different sizes (150 µm and 50 µm) and abundances (1 g/L, 2 g/L, and 4 g/L) on the anaerobic digestion (AD) of the cosmetic industry wastewater (CoIW) was investigated. The results showed that 50 µm PE-MPs did not significantly affect the cumulative biogas production compared to the control. On the other hand, three different scenarios were observed considering the different abundances of 150 µm PE-MPs. The 150 µm of PE-MPs at 4 g/L showed the most adverse effect on AD and cumulative biogas production was significantly inhibited and decreased by approximately 7 % compared to the control group, while cumulative biogas production increased by approximately 12 % at 1 g/L MP abundance. Removal of sCOD averaged 52–53 % for all abundances of 50 µm MPs. For 150 µm MPs, the sCOD removals for 1 g/L, 2 g/L, and 4 g/L were determined as 52 %, 58 %, and 56 %, respectively. Model-based analysis indicated that 50 µm PE-MPs at all MP abundances decreased the control’s hydrolysis coefficient (k). The inhibition of biogas production potential could be attributed to smaller-sized MPs having larger surface areas, so they adsorb more inhibitors in the medium and thus limit the activity of anaerobic microorganisms. In support of this, SEM results indicated that 150 µm PE-MPs surfaces possessed more erosions and grooves.
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•Degradation of polyethylene MPs was researched in the anaerobic digestion process.•Cosmetics industry wastewater (CoIW) was used as the microplastics source.•150 µm PE-MPs at 1 g/L increased biogas production compared to the control group.•Small-sized MPs (50 µm) increased the adsorption of inhibitors.•150 µm of PE-MPs at 4 g/L showed the most adverse effect on AD.