Reclaiming Nutrients and Energy From Agricultural Waste in Costa Rica

Reclaiming Nutrients and Energy From Agricultural Waste in Costa Rica

Kevin Orner, Ph.D. Student, USF Environmental Engineering & Fulbright Research Grant Recipient

The struvite reactor placed on top of the reactor stand. The liquid effluent from the biodigesters travels through the white PVC pipes to two small white storage tanks, which are covered by cloth to prevent solids from entering.

You might think that Costa Rica is only to be visited for its ecotourism opportunities. But after researching resource recovery technologies on the University of South Florida (USF) campus and with practitioners from Hillsborough County as part of his Ph.D. Dissertation, Kevin Orner is traveling to Costa Rica on a Fulbright Research Grant to investigate the recovery of nutrients and energy from pig and cow manure.

Costa Rica is a world leader in sustainability—more than 99% of the country’s energy is produced from renewable sources and approximately 28% of the country’s land is protected. However, the country only treats about 5% of its wastewater and of 93,000 farms in Costa Rica, 79,000 don’t have any treatment for their agricultural waste. There is thus a great opportunity to develop the circular economy where “wastes” can be inputted back into the production cycle (in this case for food production).

Kevin with UGA-CR team members with the newly fabricated struvite precipitation reactor.

Kevin is based at the University of Georgia-Costa Rica (UGA-CR) campus in Monteverde. There two biodigesters currently treat cow and pig manure, producing biogas that is used to heat food served in the university’s cafeteria and the digesters also produce sludge that is used for compost. Kevin has designed and now constructed with help of UGA-CR staff, a reactor that utilizes the liquid digester effluent to produce struvite (MgNH4PO4). Struvite can be used as a slow-release fertilizer. Kevin’s assessment of his reactor is considering a detail mass balance on the flow of nutrients through the reactor. It is hoped his process, if successful, will not only produces a beneficial fertilizer product from the agricultural waste but also provides better nutrient management that if not managed properly, that can cause eutrophication and loss of water quality throughout the watershed.

Fabricio Camacho, the Assistant Director at UGA-CR, has previously worked with local farmers in building several biodigesters in the community. Using his existing network, results from this study will be communicated to local farmers, students and other tourists visiting UGA-CR., and to other members of the Bellbird Biological Corridor.

The liquid from the white storage tanks will be dumped into the top of the reactor. The solids will be collected in the white cloth, and the liquid will be collected by the small blue tank and empty into the lagoons.


About the Author
PhD Candidate in Environmental Engineering at the University of South Florida

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