This issue is dedicated to microplastics in the environment, and this will be my last issue as the chief editor of the Journal of Environmental Engineering and Science. Plastics first emerged in the early 20th century, but after World War II, their commercialisation exploded. These malleable materials have transformed a variety of sectors, consumer items and even the way we package and store commodities. Improper handling of plastic waste has contributed to a major worldwide problem of microplastic contamination. Plastics can be categorised into macro-plastics (>25 mm), meso-plastics (5–25 mm), microplastics (5 mm), and nano-plastics (<0.1 mm) based on their average size. Microplastics frequently clog up natural areas, coasts and marine ecosystems. Microplastics pose a major pervasive threat to the environment, aquatic ecosystems and the very survival of humans. This themed issue contains four articles dedicated to microplastics in the environment.
The first contribution, a state-of-the-art review by Fish et al. (2023), describes microplastics in aquatic environments. They show that sources of microplastics can be categorised as primary and secondary. The textile industry is one of the primary sources of microplastics, where synthetic fabrics such as polyester, nylon and acrylic shed tiny plastic microfibres into the wastewater when used and washed. Due to their small size, these microfibres tend to bypass wastewater treatment facilities and enter natural water bodies. Secondary microplastics are fragments created from the breakdown of larger plastic pieces or macro-plastics such as plastic litter, fibre from synthetic textiles and tires. The toxicity of microplastic and nano-plastic is influenced by the additives they include, such as polymerisation links, as well as their chemical compositions. Over 90% of microplastic may be eliminated from wastewater with basic, secondary and tertiary treatment. Many physical treatments methods are currently used for the removal of microplastics (e.g., electro-sorption, membrane technologies, coagulation and flocculation, reverse osmosis and nanofiltration). However, sophisticated chemical treatment techniques are usually needed to remove microplastic and nano-plastic from water, while bioremediation has been suggested as a way to lessen the amount of microplastic in the environment.
The second contribution by Mogusu et al. (2023) describes the status of microplastic pollution in aquatic environments in Africa and its research opportunities. They suggest that chemical composition, size, density and form of the particles all play a role in the detection of microplastics in the environment. Sixteen nations in West Africa have implemented legislation banning single-use plastics. Already 34 African nations have already implemented a partial or entire ban on single-use plastics, although only eight nations have recycling requirements.
The third contribution by Goh et al. (2023) describes the combinatory effects of microplastics and emerging contaminants on alga Chlamydomonas reinhardtii. They claim that microplastics are hydrophobic and have a large specific surface area. Hence, they have noted that they interact with co-contaminants in more sensitive aquatic habitats, such as organic pollutants and heavy metals, where they may have additive, antagonistic or synergistic effects.
The fourth contribution, a review paper by Nyakundi et al. (2023), focuses on addressing environmental microplastic pollution through genetic engineering. This review focuses on leveraging protein–enzyme in genetic engineering techniques to improve catalytic performance of putative plastic biodegrading enzymes and production of environmentally friendly bioplastics from natural fibres as a substitute of synthetic petroleum-based plastics.
In order to lessen the negative contribution of microplastic on the environment, a complete plastic recycling is essential. Collection and sorting, mechanical recycling, chemical recycling and biological recycling are all steps in the recycling of plastic. Although recycling is essential, plastics that have been given a second chance with recycling still keep releasing additional microplastics (Meegoda and Hettiarachchi, 2023). Countries and organisations all around the world have taken a variety of steps to address ways of preventing and reducing the effects of microplastics, but such effort is insufficient and require additional policy interventions (Hettiarachchi and Meegoda, 2023).
