Avaliação da eficiência de remoção de fósforo em sistema de recirculação aquícola

Abstract

Intensive aquaculture is an activity that is constantly expanding around the world. However, this expansion may cause an increase in environmental impacts. In this context, the uncontrolled release of nutrients into the environment, such as phosphorus (P), stands out. Aquaculture recirculation systems (RAS) emerge as a sustainable alternative, as they reduce water consumption and allow internal treatment of effluents through biofilters and aquatic macrophytes. This study aims to quantify the phosphorus balance in a RAS intended for the cultivation of Nile tilapia (Oreochromis niloticus), evaluating its distribution in the cultivation tanks and biofilter compartments over an eight-month production cycle. Monthly water collections were carried out to determine total phosphorus (TP) using a colorimetric method, in addition to calculations of phosphorus accumulation and balance in the system. The results indicated that most of the phosphorus remained retained in the RAS itself, concentrating mainly in the biofilter compartments and, to a lesser extent, in the culture tanks, while a fraction was directed to unmonitored routes, such as sediments and assimilation by biofilter macrophytes. The overall efficiency of phosphorus removal by the biofilter was 24%, with greater retention in the initial compartments of the treatment system. It is concluded that the use of biofilters with macrophytes in RAS contributes to mitigating the phosphorus load in aquaculture effluents, promoting greater sustainability in intensive tilapia production.