Microbial biodegradation of synthetic microfibres for the sustainable application of biosolids: a review

Wastewater treatment allows for water reuse and recycling yet produces waste by-products such as biosolids which require sustainable management. Biosolids have been repurposed for soil nutrient amendment in agricultural and land rehabilitation settings. However, biosolids contain microplastics and other micropollutants which negatively affect soil, animal, and human health and contaminate surrounding environments. The most prevalent microplastics in biosolids are synthetic microfibres made from polyester, polyethylene terephthalate (PET) and nylon that are released during clothes laundering and become concentrated in sewage sludges and biosolids during wastewater treatment. Microbes isolated from various environments, including plastic waste dumping sites, garbage dumps, soils, bodies of water, and marine environments, have demonstrated the ability to degrade polyester, PET and nylon, making them promising candidates for the biodegradation of these materials. This review discusses current literature on the microplastics and microbes present in biosolids, along with microbes documented to degrade plastics that are used in microfibre production. Additionally, recommendations are made to explore biosolids-associated microbes for microplastics biodegradation, aiming to minimise soil microplastic contamination to ensure the sustainable application of biosolids as well as alternative uses for biosolids. Graphical Abstract