Abstract: Sargassum Composting (Arsenic Beaches) – Year 5
Enhancing the Quality of Sargassum Compost
Full Proposal Submitted to the HCSHWM on March 30, 2026
Principal Investigator: Helena Solo-Gabriele, PhD, Professor
Affiliation: University of Miami, Dept. of Chemical, Environmental, and Materials Engineering
Email & Phone Number: hmsolo@miami.edu, 305-989-9103
Co-Principal Investigator: Daniel Benetti, PhD, Professor
Affiliation: University of Miami, Dept. of Marine Biology and Ecology
Email & Phone Number: dbenetti@miami.edu, 305-421-4889
ABSTRACT
The amounts of seaweed (specifically the macroalgae sargassum) impacting shorelines in Florida have been increasing, resulting in beach removal and landfill disposal of this potential resource. The material is highly organic and degrades to compost easily. However, there are limitations associated with the quality of the compost. These limitations include: elevated levels of arsenic and nutrient quality, amongst other concerns. Our goal in this study is to address these two specific limitations by enhancing the breakdown of sargassum using biological decomposers, worms and black soldier fly larvae (BSFL). Both biological decomposers are known to enhance the nutrient quality of compost. We hypothesize that these biological decomposers will reduce the arsenic content of the sargassum compost by enhancing arsenic volatilization. Our prior research focused on sargassum compost has shown that about half of the arsenic from sargassum will volatilize under natural sunlight and moisture conditions, but this amount is not sufficient. We intend to assess the value-add provided by the two classes of decomposers in their ability to reduce arsenic and improve the nutrient quality in the final compost. Our objective is to conduct controlled experiments to assess the fraction of arsenic volatilized by the biological decomposers. Combinations of feedstock and decomposers that provide the highest arsenic reductions will be tested for nutrients and plant growth to assess the sargassum compost potential value within the agricultural industry. To facilitate this work, we have set up collaborations with experts in vermicomposting and in use of BSFL for valorizing waste projects.
