Efeito de fungicida e excesso de nitrogênio amoniacal no tratamento biológico de efluente de curtume

Abstract

Industrial development, has brought with it several benefits but also several environmental impacts, the generation of effluents being one of the most expressive. In this context, the tannery industry stands out, which generates effluents considered potentially polluting, due to the presence of N-NH4 + and fungicide. This study, evaluated the interference of the fungicide and the concentration of N-NH4 + in excess, on the removal of chemical oxygen demand (COD) and ammoniacal nitrogen (N-NH4 + ). For this, an aerated reactor was used, operating in a batch system. The effects of cycle time from 12 to 72 hours, fungicide volume from 0,1 to 1 mL and initial N-NH4 + concentration from 25 to 100 mg L-1 , on the COD and N-NH4 + removal were evaluated using a Central Composite Rotational Design (CCDR). The highest COD removal (45.45%), occurred under conditions of 72 hours, 0.55 mL of fungicide and 62.5 mg L1 of N-NH4 + , and the lowest COD removal (8.24%) occurred under conditions of 24 hours, 0.28 mL of fungicide and 84.8 mg L-1 of N-NH4 + . The highest N-NH4 + removal (38.49%), occurred under conditions of 42 hours, 0.55 mL of fungicide and 62.5 mg L1 of N-NH4 + , and the lowest N-NH4 + removal (4.26%), occurred under conditions of 24.1 hours, 0.82 mL of fungicide and 84.8 mg L-1 of N-NH4 + . The optimal operating values of the reactor, obtained by the desirability function were 58.1 hours of cycle time, 0.62 mL of fungicide and 57.91 mg L-1 of N-NH4 + . The mathematical models representing of the process, satisfactorily described the removal efficiency of COD and N-NH4 + , with errors of 2.81% and 4.71%, respectively. Although the removal of N-NH4 + via nitrification has shown to be an efficient technique in industrial effluent treatments, the results obtained in this study indicate that the removal of N-NH4 + was significantly affected due to the presence of the fungicide.