ISSN: 1659-2751

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Quantification of Nitrogen and Phosphorus in a Constructed Wetland in the Caribbean Zone of Costa Rica

Abstract

The total nitrogen (N) and phosphorus (P) present in the four constructed wetlands of the Integrated Livestock Farm (ILF) of EARTH University, in the Caribbean of Costa Rica was quantified in this study. These constructed wetlands treat 910 m3 of residual waters produced by the dairy and swine facilities of ILF. Five samples of water, sediments, and plant biomass were extracted from each wetland in order to determine the concentration of total N and P, in the form of P2O5. The concentration of total N and P present in the three components (water, sediments and foliar component) of the constructed wetlands at FPI was estimated at 200 kg and 30 kg, respectively, with a market value of US$ 264.34. As well, this amount of N and P corresponds to 30 sacks and 4 sacks of 45 kg of the commercial fertilizer 15:15:15. In economic terms of fertilizer, the total N represents US$ 1539.30 and the P2O5, US$ 222.70. The total volume of sediments for the four wetlands was estimated in 1468 m3, whose extraction requires an estimated of 105 machine hours with a cost of US$ 1468.39. It is necessary to remove continually these sediments in order to keep the depuration system in optimal conditions, taking advantage of the plant biomass and sediments as potential fertilizers. However, the extraction of these components to be used exclusively as fertilizers is not a profitable endeavor.

Key words: Integrated Livestock Farm (ILF), phosphorus, constructed wetland, nitrogen, P2O5.

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