Treating produced water using induced air flotation: The effect of ethanol on conditioning and flotation of PAHs in the presence of tween 80

Abstract

Induced air flotation (IAF) was used to recover the total polycyclic aromatic hydrocarbons (PAHtot) from produced water (PW), a real oilfield effluent sampled from the hydrocarbon storage tanks at SONATRACH of Bejaia. Tween 80 was used as a collector at a test concentration of 0.5% (V/V%) and ethanol was used as a frother at a test dosage of 0.5 mL/1000 mL of PW. The natural presence of NaCl at greater concentrations may improve the removal efficiency of PAHtot from PW by IAF. We found that the conditioning step before initiating the flotation process is important for PAHtot recovery. A PAHtot recovery of 93.67% was achieved at 30 min of conditioning and 20 min of flotation. We also found that in the presence of Tween 80 during the conditioning step, PAHtot have a tendency to reach the water-air surface. It was disclosed that the addition of ethanol in PW during the conditioning has reduced both the conditioning time from 30 min to 10 min and the flotation time from 20 min to 12 min, which is beneficial from an economic standpoint. The effect of ethanol on the flotation kinetics of PAHtot was explained well by the Higuchi model.