Screening of Polymeric Membranes and Optimization of Operating Conditions for the Treatment of Produced Water

Date
2013-12
Authors
Tharakshi Duraisamy, Rangarajan
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Publisher
Faculty of Graduate Studies and Research, University of Regina
Abstract

Produced water is the largest volume of waste stream obtained from oil and gas production. It affects both aquatic and terrestrial eco-systems if discharged directly into the environment. If the water is treated, it could represent a solution for water scarcity, and would reduce the impact on the environment. Membrane filtration is a type of physical treatment in which two different phases are separated upon application of an external pressure. Polymeric membranes have significant advantages such as low cost and ease of fabrication, but also major disadvantage such as fouling which directly affects the operating cost. Microfiltration (MF), ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) are four types of membrane category based on pore size. A four-stage polymeric membrane filtration process was studied for the treatment of produced water since multiple-stage membrane filtration has rarely been analyzed in the literature. Produced water was synthesized based on water quality parameters of produced water obtained from Western Canada. Water quality was analyzed after each experiment. The screening experiments were carried out at average transmembrane pressures and cross flow velocities. Based upon the rejection characteristics and permeate flux, a membrane was chosen from each of four categories. Polyvinylidene fluoride (0.3 micron), ultrafilic (100,000 MWCO), thin film (0 MWCO), and polyamide (100 Dalton) were deemed the best membranes in the four categories. The optimal transmembrane pressures of MF, UF, NF and RO were found to be 3, 4, 13 and 25 bar, respectively. The optimal cross flow velocities of MF, UF, NF and RO were found to be 0.30, 0.30, 0.90 and 0.60 m/s, respectively. The oil content, total organic carbon and sulphate ions were completely removed by the four stage filtration system. The chemical oxygen demand (COD), total dissolved solids (TDS), turbidity and chloride rejection percentages were 99.15%, 97.44%, 99.86% and 97.56%, respectively. Water quality approached that of tap water. Fouling type was analyzed based on an empirical model developed by Hermia (1982). The permeate fluxes were predicted by linear regression. The model results showed that the cake filtration model was predominant in all of the filtration types because the foulant particle sizes were large compared to the pore size of the membranes.

Description
A Thesis Submitted to the Faculty of Graduate Studies and Research In Partial Fulfillment of the Requirements for the Degree of Master of Applied Science in Industrial Systems Engineering, University of Regina. xiii, 112 p.
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