Determination of the potential for bioremediation and nutrient bioindicator of swine wastewater by floating macrophytes (Lemna minuta) - Effect of high rates of ammoniacal nitrogen

This study aimed to contribute to the sustainability of pig farming in the state of Santa Catarina, Brazil by proposing to use Lemna minuta as a bioremedy and bioindicator of wastewater. The efficiency of Lemna minuta was tested in different concentrations of ammonia nitrogen. The experiment was executed in five tanks with 5 liters each, that were feed with 2 liters of wastewater from the treatment processes in different concentrations: 100% of wastewater (Lemna 1); 75% of wastewater (Lemna 2); 50% of wastewater (Lemna 3); 25% of wastewater (Lemna 4) and the last received 100% of distilled water (Lemna 5), added floating macrophytes.. The results show that the macrophytes in the tanks Lemna 3 and 4 had better development, achieving the greatest growth and biomass formation, besides the best removal of nutrients from the liquid environment. The best overall performance was in a range of concentration of ammoniacal nitrogen between 20mg.L e 50 mg.L, the best removal efficiency was of 60% (Lemna 3). To the orthophosphate, the best remotion was 51% (Lemna 4). The increase in oxidized nitrogen indicated the nitrification and nitration process. Lemna minuta shows potential as a bioremediation for water suffering from the impact caused by pig farming, so a bioindication of pollution of this type.