# Removal of Contaminants in Water with Scallop Shell Waste
###### Abstract  
Currently, the cultivation and harvesting of mollusks is a crucial activity worldwide. However, this industry generates a large amount of mollusk shell waste disposed of in landfills, causing environmental pollution. In addition, the companies linked to this item allocate large sums of money to depositing the shells in authorized landfills. In South America, Chile is one of the leading producers worldwide of scallop shell (_Argopercte purpuratus_) waste, creating a growing environmental and financial problem in the country, especially considering that there has yet to be progress in the development of new technologies that may reuse this waste in Chile. This study used different techniques to completely characterize the northern Chile scallop shell waste's physical and chemical properties for the first time. The XRD result corresponded with calcite crystal structures (CaCO\({}_{3}\)), and the XFR showed 97.68% purity. Three particle sizes were obtained: BS (595-100 \(\upmu\)m), MS (250-595 \(\upmu\)m), and SS (\(\sim\)250 \(\upmu\)m). In addition, the potential use of these wastes to remove contaminants present in water from the wine industry (caffeic acid) and some drinking water (arsenic(III)) was evaluated. The powder with the smallest particle size (SS), which has a surface area of 1 m\({}^{2}\)/g, 0.0050 m\({}^{3}\)/g of pore volume and pore diameter of 18.0 nm, removed 100.0% of CA and 23.0% As(III) in a pH condition of 4.6. The results show that scallop shell waste can be used to treat water and reinforce polymeric matrix composite materials to improve mechanical properties. s 2024 14 3499 19 February 2024 19 February 2024 19 April 2024 19 April 2024 19 February 2024 19 February 2024 19 February 2024 19 April 2024 19 February 202  
treatments, like thermal decomposition or incineration that requires temperatures higher than 1000 \({}^{\circ}\)C [5]. Nowadays, the term blue economy is a concept that seeks a sustainable utilization of marine resources, beginning with the correct valorization of shell waste [6]. For that reason, many strategies of mollusk shell waste management and reutilization have been proposed in different fields such as environmental applications, food and feed additives, biomaterials, and construction [7]. In the case of Chile, the production of molluss reached 406 thousand tons in 2020, the country with the third highest production in the world [1]. Among the most frequently farmed molluss are the mussel (_Mytilus chiliensis_), choro (_Choromytilus chorus_), cholla (_Aulacomya ater_), Chilean oysters (_O. chiliensis_), Pacific oysters (_C. gigas_), and the northern oyster or scallop (_Argopecten purpuratus_) [8]. The latter is distributed from the coasts of Nicaragua to the city of Valparaiso in Chile, but it is located mostly between the first and the fourth region of Chile because the geography of these places benefits their growth. In recent decades, this resource has seen a great demand, which is why various artificial crops have been placed on the shores of those regions to sustain the commercial activity [9]. At the moment, northern scallop production in Chile is concentrated in just a third of the companies founded at the beginning of this industry, and the industry is focused on production volumes with the main challenge being to develop technology to reduce production costs [10]. The Coquimbo region (IV region, Chile) has 93.9% of the national production of northern scallops, which was 3654 tons in 2021 [11]. This mollusk is in great demand due to its high nutritional value, being a good source of tryptophan, vitamin B12, minerals, and an interesting amount of omega-3 fatty acids (EPA and DHA). It is mainly exported, without shells or with only one of them, to countries such as France (87% of the volume exported), Italy (6.7%), and Spain (3.3%) [12]. Consequently, this causes a large amount of shell waste in the region after the cleaning and packaging process to be sold abroad.