Treatment of Bullfrog Farming Wastewater in a Constructed Wetland

Abstract

The aim of this study was to install and assess the efficiency of a constructed wetland for wastewater treatment from bullfrog farming (Lithobates catesbeianus) at fattening growth phase. Water detention time was not controlled since wastewater input flow varied according to the biomass of animals maintained in stalls. The study was divided into two phases, with higher and lower bullfrog biomass respectively for phase I and II. A higher removal of nitrite, biochemical oxygen demand, and thermotolerant coliforms was observed at phase I whereas a higher removal of turbidity, nitrate, total phosphorus, total suspended solids, total dissolved solids, and chlorophyll a occurred at phase II. Wastewater treatments using constructed wetland systems with high organic load require a higher water detention time for a better load removal. The treatment effect was positive since this wastewater flowed directly into fishponds or streams, which might promote eutrophication. Thus, wastewater treatment is essential to minimize the impact caused by frog farming on receiving water bodies, promoting the sustainability of this activity in Brazil.