18 th International Conference on Environmental Science and Technology Athens, Greece, 30 August to 2 September 2023 EPS waste management from coastal cleaning actions: identification of contamination sources, collection, treatment, and re-use in cement-based materials ALEXOPOULOS N.D. 1* , FILIPPIDIS A. 2 , LEKKAS D.F. 3 , METAXA Z.S. 4 ., PROKOPIOU V. 4 1 Research Unit of Advanced Materials, Department of Financial Engineering, School of Engineering, University of the Aegean, 41, Kountouriοtou str, 82132, Chios, Greece 2 «OZON» Non-Governmental Organization, Loutra Oreas Elenis, 20100, Corinth, Greece 3 Waste Management Laboratory, Department of Environmental Studies, University of the Aegean, Mytilene, 81100, Greece 4 Department of Chemistry, International Hellenic University, St. Luke, Kavala, 65404, Greece, *corresponding author: Alexopoulos Nikolaos, e-mail: nalexop@aegean.gr Abstract Finding sustainable solutions to reduce plastic waste in response to today's global environmental challenges is a high priority for the scientific community. Collaboration among many scientists with diverse research interests is the key to success for integrated proposals for the collection, treatment, and reuse of recyclable waste. This study presents proposals for integrated EPS waste management, from identifying pollution hotspots to collection routes, especially on the coast where waste is more abundant and leaves a larger footprint, to reuse in cement-based materials. This paper discusses the various options for recycling low-grade EPS and the potential applications of mortar or concrete containing EPS collected on the coast. The multiple benefits are not limited to reducing EPS waste, but benefit the entire planet, from reducing aggregate consumption to improving building insulation. Keywords: EPS, cement, circular economy, waste management, reclaiming, retrieval, recovering, recapturing 1. Introduction Expanded polystyrene (also known as EPS or "Styrofoam") was first discovered in 1839. Its use increased rapidly during World War II, primarily because of its light weight and insulating properties and its use in military aircraft. Today, it is a widely used product in everything from energy-efficient building insulation and food packaging to disposable restaurant materials and soilless hydroponic horticulture. For many years, EPS was considered a "miracle product." That has changed, and it is now referred to as the "nightmare of waste" The reason EPS is referred as one of the most difficult wastes to dispose of is its properties. It is a non-biodegradable material that takes hundreds of years to decompose. It also takes up a lot of space in rubbish dump. EPS also contains toxic substances, styrene and benzene, and the polystyrene beads formed by polymerization are tiny and durable (Visvanathan et al., 2007). The main sources of EPS pollution are municipal waste, but it is also an important source of marine pollution. Research shows that 80 % of all ocean pollution originates from the land, which points to toxic, land-based EPS trash as the primary culprit (Smith, 2015). Unfortunately, EPS packaging products end up in landfills after consumption, creating a significant amount of waste that is an environmental burden. It is important to note that polystyrene (PS) has accounted for about 10 % of all plastic waste in the last decade, ranking it as one of the most important post-consumer wastes. The main disadvantage of EPS is its very low recycling rate. The behavior of EPS in the ocean shows that it decomposes in seawater, is not biodegradable - and eventually enters the food chain via marine fauna (Consoli et al., 2018). Its properties as a lightweight, waterproof, and floating material combined with its insulating properties make it a popular choice for the marine materials industry. Major applications include fishing, aquaculture, floating buoys, food packaging, such as fish boxes, the interior of floating media, harbor platforms, and more. EPS space debris poses a chemical and physical hazard to marine life. Polystyrene foam poses a threat because it tends to quickly turn into microplastics, and microplastics pose a dual problem: First, it can be consumed by almost all marine life, and second, it can absorb large amounts of toxic chemicals due to its large surface-to-volume ratio, e.g., (Bakir et al., 2016; Consoli et al., 2018). Global production forecast indicators of EPS are shown in Figure 1, which indicates that production is expected to increase through 2029 (Exactitude Consultancy, 2022), although environmental drawbacks have been pointed out. Global cumulative plastic production since 1950 is projected to increase from 9.2 billion tons in 2017 to 34 billion tons in 2050, as shown in Figure 2 (GRID-Arendal, 2021). There is therefore an urgent need to reduce the production of virgin plastics, reduce the amounts of uncontrolled or poorly managed waste entering the oceans, and increase the recycled content of plastic waste, currently estimated at less than 10 %. EPS is technically recyclable, but due to its large volume relative to weight, it takes up a lot of space, is not properly managed, and is not recycled. This creates challenges for waste management centers. Transportation to recycling centers is not cost-effective, considering fuel and other transportation costs, as well as the low value of the material