RESUMO
One of the main problems faced by the oil industry is related to the amount of produced water generated during the oil extraction process. For proper disposal of this effluent, treatment processes should be applied to meet the requirements established by environmental agencies. Thus, the present study aimed to evaluate the efficiency of the combination of electroflotation process and down-flow granular filtration in the treatment of wastewater contaminated with oil. To this end, they were studied in a pilot system, to optimize the electroflotation process and combination of processes. The performance of the pilot system was determined by removal of oil and grease content (OG) in the treated effluent. According to the results, the electroflotation process had the best performance with an effluent input rate of 62â m3â m-2â d-1, current density of 80â Aâ m-2 and NaCl concentration of 7900â mgâ L-1. Under these conditions, the mean removal of OG from synthesized solution after 720 minutes of treatment was 86.64% (59.51â mgâ L-1) for the electroflotation process and 61.52% (12.91â mgâ L-1) after down-flow granular filtration. By combining the processes studied, we obtained an initial OG removal (470.55â mgâ L-1) of over 98% (6.42â mgâ L-1) in 720 minutes of treatment, with an energy consumption of the electrochemical reactor of 1.47â kWhâ m-3. ABBREVIATIONS: ANOVA: analysis of variance; CCRD: Central Composite Rotational Delineation; DOC: dissolved organic carbon; DSA: dimensionally stable anodes; LAPOA: Laboratory of Water Potabilization; OG: oil and grease; OPER: operating parameters of the electrochemical reactor; TDS: total dissolved solids; UFSC: Federal University of Santa Catarina.