Otimização de parâmetros operacionais para tratamento de lixiviado utilizando processo Fenton

Abstract

This study aimed to determine the best operating conditions of Fenton process for treatment of landfill leachate. The leachate collected from the landfill belongs to the metropolitan area of João Pessoa-PB and the experimental system was monitored on the premises Experiment Station Biological Treatment of Sewage (EXTRABES) of the State University of Paraíba in the city of Campina Grande-PB. Oxidation tests, coagulation/flocculation and sedimentation were carried out to examine the following operating parameters: Fenton reagent dosing (1, 2 , 3, 4 , 5, 6 , 8 and 12 gFe ), molar ratio [H 2 O 2 ]/[Fe 2+ ] (1, 2, 3, 6, 9 and 12), pH of oxidation (2, 3 and 4), oxidation time (5, 10, 15, 20 and 30 min), flocculation time (10, 20, and 30 min) and settling time (10, 15, 20 and 25 min). Assays were performed in Jar Test. All steps were submitted to the following methodology: for each jar, added the leachate, the FeSO 4 .7H 2 O, H 2 O and pH oxidation was adjusted with HCl. Under mechanics stirring (400 rpm) and after 10 seconds of rapid mixing, begins to count the oxidation time. After oxidation, added the alkalizing agent (NaOH) to pH 8.0, followed by a rapid mixing time of 10 seconds (400 rpm). Waited, then, the flocculation time (40 rpm) and, then, the settling time. A sample was collected and analyzes were performed according to the methods recommended by APHA (2005). After each step, was realized analysis of variance (ANOVA) and GT-2 method for defining the best result. The best results, under the conditions of this study were obtained with a Fe 2+ 2 concentration of 5 g.L -1 , molar ratio [H 2 O 2 ]/[Fe 2+ ] 9, pH of oxidation 2, oxidation time 20 min, flocculation time of 10 min, sedimentation time 15 min, with removal of 67% COD and 93% of true color. The final remaining COD was 3.84 gO and the true color of the final remnant was 394 uH. Obtained a high removal nitrite (93%), nitrate (69%), total phosphorous (97%), soluble orthophosphate (99.8%) and ammonia (87%). The addition of ferrous sulphate led to an increase in the concentration of total solids in the leachate, since the concentration of Fe contributes to the production of sludge in the process.