A.M. Vazquez - Faculty of Chemical Sciences, National University of Asunción, FCQ/UNA, Asunción, Paraguay
A. Samudio-Oggero - Laboratory of Biotechnology, Multidisciplinary Technological Research Center, National University of Asunción, CEMIT/UNA, Asunción, Paraguay
H.D. Nakayama - Laboratory of Biotechnology, Multidisciplinary Technological Research Center, National University of Asunción, CEMIT/UNA, Asunción, Paraguay
I. Cantero-García - Laboratory of Biotechnology, Multidisciplinary Technological Research Center, National University of Asunción, CEMIT/UNA, Asunción, Paraguay

BACKGROUND AND OBJECTIVES: The Municipal Park of Areguais is located in the Central Department of Paraguay. Part of this Park is within the area of influence of Ypakarai Lake, which is widely recognized by vacationersfor its natural spaces. Despite being one of the most representative ecological reserves in the country, annual waterquality reports indicate the presence of a high content of pollutants; mainly nitrogen, phosphorus, andfecalcolifoirs, among others. These conditions promote the proliferation of cyanobacteria which consume the available oxygenand compromise the reserve’s flora and fauna. Following several laboratory tests, the present work has the objective of evaluating the impact of thepark’s recently constructed wetland’son the treatment of residual waters.There are several parameters evaluated in thisstudy of final wastewater discharge disposal treatmentthrough a constructed wetland of horizontal flow with Typhadomingensis. The objective is to develop an adequate system for the treatment of residual waters that can be replicated in places with similar conditions.METHODS: The evaluation consisted of analyzing the residual water and finding the removal percentage for each of the following parameters such as chemical oxygen demand; biochemical oxygen demand; total phosphorus; total nitrogen; fecal coliforms; hydrogen potential; and temperature. The quality of the treated water was determined by comparing it with the limits established in Article ۷ of Resolution Number ۲۲۲/۰۲ of the Environment Secretary for effluents. The results demonstrate that this system is aviableoption for the removal of fecal coliforms and nutrients such as phosphorus and nitrogen.FINDINGS: In terms of the quality of the treated water, the parameters studied are within the limits,established by Resolution Number ۲۲۲/۰۲of the Environment Secretary for Class ۲ waters, for water to be discharged into the receiving body. The results obtainedwere: ۸۸.۹ percent fecal coliform removal; ۸۴.۹ percent total nitrogen; ۷۳.۳ percentchemical oxygen demand; ۶۱.۴ percent biochemical oxygen demand; and ۱۴.۲ percent Total Phosphorus. Considering Resolution ۲۲۲/۰۲, the biochemical oxygen demand, Total Nitrogen, and Total Phosphorus were outside the admissible limits.CONCLUSION: It is very feasible for wastewater generated in public parks to be treated through the construction of sub-surface flowwetlands.This study confirms that the treated wastewater is within the establishedlimitsfor all the parameters: temperature, hydrogen potential, biochemical oxygen demand, chemical oxygen demand, total nitrogen, total phosphorus, and fecal coliforms. This model of water treatment can be easily adopted.

Bioremediation, Black water, Constructed wetlands, Typha domingensis