Assessing quality and beneficial uses of Sargassum compost

Afeefa A Abdool-Ghany; Clément G L Pollier; Amanda M Oehlert; Peter K Swart; Trent Blare; Kimberly Moore; Helena M Solo-Gabriele

doi:10.1016/j.wasman.2023.09.030

Assessing quality and beneficial uses of Sargassum compost

Waste Manag. 2023 Oct 6:171:545-556. doi: 10.1016/j.wasman.2023.09.030. Online ahead of print.

Authors

Afeefa A Abdool-Ghany¹, Clément G L Pollier², Amanda M Oehlert², Peter K Swart², Trent Blare³, Kimberly Moore⁴, Helena M Solo-Gabriele⁵

Affiliations

¹ Department of Chemical, Environmental, and Materials Engineering, College of Engineering, University of Miami, Coral Gables, FL, USA.
² Department of Marine Geosciences, Rosenstiel School of Marine, Atmospheric and Earth Science, University of Miami, Key Biscayne, FL, USA.
³ Department of Food and Resource Economics, University of Florida, Gainesville, FL, USA.
⁴ University of Florida, Institute of Food and Agricultural Sciences, Fort Lauderdale Research and Education Center, 3205 College Avenue, Davie, FL, USA.
⁵ Department of Chemical, Environmental, and Materials Engineering, College of Engineering, University of Miami, Coral Gables, FL, USA. Electronic address: hmsolo@miami.edu.

PMID: 37806162
DOI: 10.1016/j.wasman.2023.09.030

Abstract

Sargassum spp. (specifically Sargassum fluitans and S. natans), one of the dominant forms of marine macroalgae (seaweed) found on the beaches of Florida, is washing up on the shores throughout the Caribbean in record quantities. Currently, a common management option is to haul and dispose of beached Sargassum in local landfills, potentially wasting a valuable renewable resource. The objective of this study was to determine whether composting represents a feasible alternative to managing Sargassum inundations through measurements and comparisons to eleven guidelines. Specifically, we assessed the characteristics of the compost [physical-chemical parameters (temperature, moisture content, pH, and conductivity), nutrient ratios (C:N), elemental composition, bacteria levels, and ability to sustain plant growth] in both small- and large scale experiments. Results show that although nutrient concentration ratios were not within the standards outlined by the U.S. Composting Council (USCC), the Sargassum compost was able to sustain the growth of radishes (Raphanus sativus L., var. Champion). Trace metal concentrations in the compost product were within five regulatory guidelines evaluated, except for arsenic (As) (6.64-26.5 mg/kg), which exceeded one of the five (the Florida Soil Cleanup Target Level for residential use). Bacteria levels were consistent with regulatory guidelines for compost produced in large-scale outdoor experiments but not for the small-scale set conducted in enclosed tumblers. Overall results support that Sargassum compost can be beneficially used for fill and some farming applications.

Keywords: Arsenic; Compost; Metals; Nutrients; Sargassum; Seaweed.