Oil Removal From Produced Water Using Natural Materials

Abstract

The oil and gas industry has had to deal with a massive amount of waste water as a bi-product of the exploration of oil and gas. This waste water referred to as produced water (PW) and the amount of PW increases with the well operation time and may increase to approximately 80%. The discharge of PW may lead to severe pollution of surface, soil and under-ground water. Oil-field-produced water contains organic and inorganic compounds. One commonly used technique to remove oil from PW is adsorption. In this work, pomegranate peel powder (PPP) is used as a low cost adsorbent for the removal of crude oil from simulated produced water (SPW) and real PW from oil and gas wells. Pomegranate peels (agricultural waste) were dried, crushed and washed with double distilled water and dried again. Characterized for surface morphology, elemental composition, functional groups and surface area using analytical equipment like SEM, EDS, FTIR, and BET isotherm respectively. EDS spectroscopy showed that the major elemental constituent in the bio-sorbent was carbon (up to 78%). However, oxygen, calcium, silicon and potassium were also observed in small quantities. Oil was removed from laboratory-produced water in a batch process at standard atmospheric conditions. The effect of contact time, adsorbent dosage, pH as well as temperature on the removal efficiency of oil was investigated. The optimum parameters for oil removal were: pH = 9.5, pomegranate = 2.33 g/L, contact time = 40.0 minutes and adsorption temperature = 55.0 C. The results showed that as the adsorbent dosage, pH and salinity of SPW are increased, the removal efficiency increased. The adsorption of crude oil by PPP was found to follow the Langmuir adsorption isotherm with an adsorption capacity of 555 mg/g. The adsorption kinetic of crude oil is best described by the pseudo-second-order kinetic model with a rate constant of 3.75 x 10-4 g/mg.min. These results render PPP an excellent adsorbent for the removal of oil from produced water with an oil removal efficiency exceeding 92% in 50 min.