Manejo ecológico aplicado ao tratamento de efluentes de aquicultura continental

Abstract

Fish farms effluents are rich in nutrients and solids that can increase eutrophication and silting in the natural water downstream. Environmental agencies in Brazil have been standardizing mechanisms to control and regulate continental fish farming activities, establishing rules that aim, in particular, for the treatment of effluents. In this way, studies involving different types of effluent treatment can guarantee the environmental sustainability of aquaculture activity by minimizing its impacts on aquatic ecosystems. Effluent treatment in sedimentation basins, using aquatic macrophytes used in multitrophic systems can bring positive results for continental fish farming in compliance with current regulations. Aquatic macrophytes act as biofilters, playing an important role to control eutrophication. Here, we identified that fish farms in valleys, without an effluent treatment system, can contribute to the eutrophication downstream, regardless of the season, they transformed the water inlet classified as mesotrophic into an effluent wich is supereutrophic, and did not meet Brazilian regulation (CONAMA n° 357 - class II). Testing the effect of different macrophytes in the treatment of fish farming effluents in static mesocosms, we identified that Pistia stratiotes showed greater efficiency to reduce phosphorus in the effluent, and has better management characteristics to be used in fish farming effluent treatment systems. The ecological management applied to the effluent treatment of fish farming, using only the sedimentation basin, proved to be efficient in reducing water quality parameters, adapting most of the analyzed parameters to the current environmental regulations, and generated less solid waste than the other treatments, that associated fish with different eating habits and macrophytes.