To celebrate Open Access Week, we'll be posting a new OA Ambassador Spotlight Blog each day!
Our OA Ambassadors raise awareness in their local communities about global OA movements as well as related opportunities through IWA Publishing. They are representatives of both the International Water Association and IWA Publishing and our joint goals to empower the next generation of water leaders and to shape the future of the water sector. These blog posts highlight their specialty and research focus, as well as emphasising the importance of Open Access publishing.
Dr Alaa El Din Mahmoud is an Assistant Professor in the Environmental Sciences Department at Alexandria University. His research focuses on interdisciplinary environmental issues including waste valorization, water/wastewater treatment, microplastics, circular economy, machine learning and green nanotechnology. Connect with Dr. Alaa on LinkedIn!
Plastics are employed in a wide variety of commercial and industrial purposes and are one of the major inorganic solid waste fractions in daily municipal solid waste (MSW) production [1]. One of the major new concerns to the worldwide environmental community is microplastics (MPs). MPs are tiny plastic particles between 1 µm to 5 mm in size, and they are identified as persistent contaminants in the environment [2].
MPs are an extremely heterogeneous particle ensemble, which vary in size, color, shape, and density in addition to a wide variety of synthetic polymers. In addition, there are around 13,000 compounds connected to plastics, several of those compounds are of concern due to their high toxicity. Most of these chemicals such as polyvinyl chloride (PVC) and Perfluoroalkyl and Polyfluoroalkyl Substances (PFAS) are linked to cancers and endocrine disruption. MPs are often classified into two categories: primary and secondary.
Primary microplastics come from the production or use of plastic items. Tyre abrasion, road markings, fabrics, marine coatings and laundry are examples of primary microplastics. Boucher and Friot [3] reported that 15-31% of plastics found in the water come from primary sources. Whereas secondary micro-plastics are the type that originated as a result of breakdown of larger plastic items.
Environmental Issues
In spite of the recycling awareness around the world, only ~15% of plastic waste is collected for recycling and half of this percentage ends up discarded. Many plastic products are placed in markets that lack the capacity to collect and safely dispose of them. A systemic approach can lead to a fundamental transformation of the global plastics economy [4].
A plastic bag takes 10 to 20 years to totally disintegrate in the ocean. The time required for a PET bottle to break down in water and become micro plastics that settle to the seafloor is substantially longer – 450 years [5].
Up to 14 million tons of plastic ends up in the ocean annually, causing $13B in damage. Hundreds of thousands of marine animals are suffocated by plastic each year and microplastics are contaminating our soil, water and food. MPs can be ingested by even the smallest marine organisms, such as plankton. The study also found that microplastics can disrupt the growth and development of plankton, which could have a cascading effect on the entire marine food web [6].
Due to the increase of marine microplastic pollution since 1980, those MPs could affect at least 267 animal species. For instance, MPs could affect 86%, 44%, and 43% of marine turtles, sea birds, and marine mammals, respectively. Additionally, they affect and alert the rate of fish reproduction and cause a reduction in the growth and the development of amphipods, water fleas, coral, and sea urchins [7, 8].
Sustainable Solutions
Separation and degradation are the two primary approaches used for MP cleanup in wastewater treatment plants (WWTPs) [9]. Separation techniques include grids, screens, sedimentation, and disc filtering. Chemical remediation is a procedure that involves mixing chemicals into the wastewater to speed up the breakdown of microplastics or to entrap them in floc before they settle. Unfortunately, most MPs collected by WWTPs can be discharged into the environment through reject streams, sludge, or waste membrane.
Membrane technology has been used as one of the flexible methods for eliminating MPs from aquatic bodies. This treatment could manage a sizable input stream that contains both brackish water and seawater. Traditional filtration methods use membranes with micrometer- or nanometer-sized pores to retain the tiny solids. Dynamic membrane technology uses a newly formed cake layer on supporting membrane through filtration, which serves as a barrier or foulant formed when microplastics and other fragments in the wastewater are initially getting filtered [10, 11]. An emerging class of membrane known as a photocatalytic membrane combines physical membrane separation with chemical photocatalyst degradation to improve water and wastewater treatment. This methodology offers a compelling way to merge two microplastic treatment methods based on the principles of capture and degradation into a single entity [12].
In 2022, the United Nations organized the UN Plastics Summit in Uruguay to create a legally enforceable instrument on plastic pollution in recognition of the significance of addressing worldwide plastics pollution. In addition, the Assembly of UN Environment agreed to develop a global treaty to end plastic pollution. Negotiations are currently underway. This treaty is hailed as the most important environmental deal since the Paris Agreement on climate change. Without radical action, plastic pollution will triple by 2060. A concerted global approach is urgently needed to tackle this crisis. A treaty draft is expected by the end of 2024.
MP contamination issues can be controlled by implementing the following points:
- educating consumers about the MP issue and its source, impact, and fate
- applying sustainable life cycle business models.
- creating eco-friendly, reusable and recyclable materials
- creating cutting edge recycling methods with less environmental impact
References
1. Kibria, M.G., et al., Plastic waste: challenges and opportunities to mitigate pollution and effective management. International Journal of Environmental Research, 2023. 17(1): p. 20.
2. Khan, N.A., et al., Microplastics: Occurrences, treatment methods, regulations and foreseen environmental impacts. Environmental Research, 2022. 215: p. 114224.
3. Boucher, J. and D. Friot, Primary microplastics in the oceans: a global evaluation of sources. Vol. 10. 2017: Iucn Gland, Switzerland.
4. Mahmoud, A.E.D., M. Fawzy, and N. Khan, Artificial Intelligence and modeling for Water Sustainability: Global Challenges. 1st Edition ed. 2023: CRC Press. .
5. Jones, E.S., et al., Distributions of microplastics and larger anthropogenic debris in Norfolk Canyon, Baltimore Canyon, and the adjacent continental slope (Western North Atlantic Margin, USA). Marine pollution bulletin, 2022. 174: p. 113047.
6. Nava, V. and B. Leoni, A critical review of interactions between microplastics, microalgae and aquatic ecosystem function. Water research, 2021. 188: p. 116476.
7. Hitchcock, J.N. and S.M. Mitrovic, Microplastic pollution in estuaries across a gradient of human impact. Environmental pollution, 2019. 247: p. 457-466.
8. Tang, J., et al., Acute microplastic exposure raises stress response and suppresses detoxification and immune capacities in the scleractinian coral Pocillopora damicornis. Environmental pollution, 2018. 243: p. 66-74.
9. Devi, A., et al., Microplastics as an emerging menace to environment: Insights into their uptake, prevalence, fate, and sustainable solutions. Environmental Research, 2023. 229: p. 115922.
10. Krishnan, R.Y., et al., Recent approaches and advanced wastewater treatment technologies for mitigating emerging microplastics contamination–A critical review. Science of The Total Environment, 2023. 858: p. 159681.
11. Chen, J., et al., How to build a microplastics‐free environment: strategies for microplastics degradation and plastics recycling. Advanced Science, 2022. 9(6): p. 2103764.
12. Goh, P., et al., Nanomaterials for microplastic remediation from aquatic environment: Why nano matters? Chemosphere, 2022. 299: p. 134418.