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Degradation of Some Polymeric Materials of Bioreactors for Growing Algae

Journal of Contaminant Hydrology 2026
Ewa Borucińska-Parfieniuk, Ewa Górecka, Jakub Markiewicz, Urszula J. Błaszczak, Krzysztof J. Kurzydlowski, Izabela B. Zglobicka

Summary

Exposure of PMMA, polycarbonate, and PET polymer panels to 70 days of bioreactor conditions caused an average 15% loss in optical transparency, increased surface roughness, and reduced contact angles across all materials, with PET performing worst and PMMA showing the highest optical stability. This accelerated aging study directly documents how commonly used transparent plastics degrade under aquatic and light exposure, producing surface microstructural changes consistent with early-stage microplastic and nanoplastic generation.

Transparent polymeric materials such as poly(methyl methacrylate) (PMMA), polycarbonate (PC), and polyethylene terephthalate (PET) are widely used as glass alternatives in algal bioreactors, where optical clarity and mechanical stability are crucial. However, their long-term use is limited by surface degradation processes. Photodegradation, hydrolysis, and biofilm accumulation can reduce light transmission in the 400-700 nm range essential for photosynthesis. This study examined the aging of PMMA, PC, and PET under bioreactor conditions. Samples were exposed for 70 days to illumination, culture medium, and aquatic environments. Changes in their optical transmittance, surface roughness, and wettability were analyzed. All polymers exhibited measurable surface degradation, characterized by an average 15% loss in transparency, significant increases in surface roughness, and reduced contact angles. PMMA demonstrated the highest optical stability, maintaining strong transmission in key blue and red spectral regions, while PET performed the worst, showing low initial clarity and the steepest decline. The most severe surface degradation occurred in areas exposed to the receding liquid interface, highlighting the need for targeted cleaning and/or a reduction in the size of the liquid-vapor transition zone. Overall, the results identify PMMA and recycled PMMA (PMMAR) as durable, cost-effective materials for transparent bioreactor walls.

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