Tratamento de lixiviado de aterro sanitário por eletrocoagulação

Abstract

Sanitary landfill sites are widely used to dispose urban solid waste. In the sanitary landfills the urban solid waste overcome degradation by different methods, such as physical, chemical, and biological, originating the Landfill Leachate (LL). LL is characterized by containing refractory, non-biodegradable compounds, and emerging contaminants, which present a high potential to impact water sources generating problems such as eutrophication, salinization, acidification, destruction of aquatic flora / fauna, among others. Conventional treatment processes used to present a limited efficiency in removing the pollutants from LL. Thus, aiming to reach an efficient method to be applied for landfill leachate treatment, this work presents a newly Electro-Coagulation (EC) reactor, designed with electrodes in the baffles form, increasing the hydraulic detention time. Then preliminary tests using the new designed EC reactor were performed, providing 50% of Aromatic Compounds derived from benzene (Abs 254 nm) and 80% of Color (Pt Co mg L-1) within 63 min of electrolysis, under the following operational conditions: initial pH of 6.5; current Intensity of 17 (A); current density (CD) of 12.45 (A m-2); 2 cm of electrode gap; flow rate of 700 (ml min-1); landfill leachate processed volume of 4.5 L. Aiming to increase the EC process efficiency an experimental design based on data obtained in the preliminary tests was performed. For the experimental design tests of the Central Rotational Design (CRD) the Current Intensity ranged from 7.3 and 18.6 and the solution pH varied between 3.8 and 8.1 within 63 min of electrolysis. The removal rates of Aromatic Compounds derived from benzene (Abs 254 nm) and color (Pt Co mg L-1), obtained by the experimental design varied from 0 to 76% and 2.7 to 98.9%, respectively. From these results, the influence of current Intensity and solution pH was highlighted, as well as the efficiency of the newly designed EC reactor for the LL treatment. The positive results may make possible the scale-up of the EC reactor, presenting the alternative to be used as a pre or post-treatment of LL, decreasing the environmental impacts posed by LL.