Coconut filters woven using Native Hawaiian techniques capture coastal microplastic and sunscreen pollution and support fungal bioremediation

Abstract

Microplastic pollution and sunscreen contaminants increasingly threaten coastal ecosystems, yet many existing clean-up solutions rely on synthetic materials, creating additional carbon emissions during manufacturing, or address pollutant removal without subsequent treatment, leaving risk of future run-off back into the ocean. Here we evaluate coconut husk, an abundant and biodegradable agricultural byproduct, as a dual-function platform for physical pollutant capture and microbial bioremediation applications. To test the natural microbial community of coconuts for bioremediation potential, we isolated fungi from coconut husks and screened their growth under plastic- and sunscreen-containing conditions. 24 fungal isolates grew on plastic- and/or sunscreen media, with several isolates belonging to genera previously documented to degrade plastic, i.e. Chaetomium, Curvularia, Meyerozyma, Cladosporium, and Fusarium. We then developed filtration modules using coconut husks, fiber, and leaves, basing our design on traditional Hawaiian papale lau niu (coconut leaf hat) weaving. In filtration trials, the woven devices captured up to 76.58 +/- 3.73% of suspended microplastic particles in 2 minutes and captured suspended sunscreen with a 533.51 +/- 0.81 NTU decrease in net turbidity of the surrounding water than in control trials with no filter. Overall, this work introduces a form of natural innovation for pollution clean-up, building on coconut-based materials, traditional techniques, and microbial resilience to create a sustainable and cost-effective system.