Mentor: Mark Krekeler, Ph.D.

Previous studies have shown that beach sand possesses properties that make it a viable aggregate for use in subsurface flow constructed wetlands. When combined with additional carbon sources and refined to a medium grain size (< 600 μm), sand can serve as an effective filtration medium capable of adsorbing heavy metals such as copper (Cu), lead (Pb), zinc (Zn), and mercury (Hg). These contaminants are commonly found in urban areas, particularly near industrial infrastructure like coal combustion plants. The risk of pollution is often heightened in communities affected by natural disasters and marginalization. One such area is Guayama, Puerto Rico, where a coal-fired power plant once operated, emitting heavy metal pollutants that pose serious health and ecological threats. This study aims to mitigate such pollutants by evaluating the effectiveness of a custom filtration medium composed of Playa Buyé sand from Puerto Rico and coconut-based carbon. The research investigates the medium's ability to remove Cu, Pb, Zn, and Hg as individual contaminants and as a mixed solution to better simulate real-world runoff conditions. Physical and geochemical analyses were performed on Playa Buyé sand and coconut carbon products. A filtration medium was developed using a 90:10 mixture of sand and a coconut carbon blend (CCmix). Additional chemical analyses were conducted post-adsorption to assess the medium’s contaminant removal capabilities. Findings from this study support the use of this locally sourced, sustainable filtration medium in constructed wetlands. The results demonstrate the possibility of natural materials like sand and coconut carbon to create affordable, community-based solutions for heavy metal pollution.

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