Combination of electroflotation process and down-flow granular filtration to treat wastewater contaminated with oil

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 62 m³ m^-2 d^-1, current density of 80 A m^-2 and NaCl concentration of 7900 mg L^-1. Under these conditions, the mean removal of OG from synthesized solution after 720 minutes of treatment was 86.64% (59.51 mg L^-1) for the electroflotation process and 61.52% (12.91 mg L^-1) after down-flow granular filtration. By combining the processes studied, we obtained an initial OG removal (470.55 mg L^-1) of over 98% (6.42 mg L^-1) in 720 minutes of treatment, with an energy consumption of the electrochemical reactor of 1.47 kWh m^-3.

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.