Evaluating Compost as a Means to Recycle Sargassum Macroalgae (Seaweed) Full Proposal Submitted to the HCSHWM on April 8, 2020
Principal Investigator: Dr. Helena Solo-Gabriele, University of Miami, Dept. of Civil Arch. and Environ. Engineering, hmsolo@miami.edu, 305-284-3467
Co-Principal Investigator: Dr. Peter Swart, University of Miami, Dept. of Marine Geosciences – Rosenstiel School of Marine and Atmospheric Science, pswart@rsmas.miami.edu
Co-Principal Investigator: Dr. Amanda Oehlert, University of Miami, Dept. of Marine Geosciences – Rosenstiel School of Marine and Atmospheric Science, aoehlert@rsmas.miami.edu
Lead Graduate Student: Afeefa Abdool-Ghany, University of Miami, Dept. of Civil Arch. and Environ. Engineering, aaa625@miami.edu
ABSTRACT
Sargassum spp. is one of the dominant forms of marine macroalgae (seaweed) found at beaches throughout Florida. During the summer of 2018 and 2019, record amounts of Sargassum spp. were documented along beach coastlines resulting in local authorities hauling this seaweed to the nearest landfill. Hauling and landfill disposal of seaweed can cost as much as $35 to $45 million a year per county, especially for Florida coastal counties. Once in the landfill, the seaweed begins to rot and can release hydrogen sulfide. Coastal counties are looking for alternative ways to handle the material once removed from the beach. Composting offers one potential alternative. One limitation of seaweed compost is its potential to contain excess salts which can be detrimental to plant growth. The objective of this proposal is to evaluate the suitability of producing compost from seaweed. The project will be divided into two phases. The first phase will involve two tumbler composters with four compartments (washed, unwashed, unwashed mixed with green yard waste, and unwashed mixed with woody yard waste). The second phase will involve two larger scale compost piles with different washing methods (washed versus unwashed seaweed). Each of these phases will be analyzed for bulk physical-chemical properties of the compost (including salinity), nutrients (including carbon, nitrogen, and phosphorus), metals, and bacteria. Results will be compared with a) plant growth requirements, b) Florida soil clean up target levels (SCTLs), and c) sewage sludge land application guidelines to preliminarily evaluate the suitability of the seaweed compost. For the second phase, the research team will partner with the City of Hallandale. They will provide the resources to move the seaweed (front end loaders and trucks), to rinse the seaweed, and will provide a secure space to conduct the larger scale composting experiments.