The Effect of Ceramic Membranes’ Structure on the Oil and Ions Removal in Pre-Treatment of the Desalter Unit Wastewater

Abstract

Salts, organic materials, and hazardous materials can be found regularly in the effluent from a desalter unit of crude oil. These materials should be separated from the wastewater. Four kinds of inexpensive and innovative ceramic microfiltration membranes (mullite, mullite-alumina (MA 50%), mullite-alumina-zeolite (MAZ 20%), and mullite-zeolite (MZ 40%)) were synthesized in this research using locally available inexpensive raw materials such as kaolin clay, natural zeolite, and alpha-alumina powders. Analyses carried out on the membranes include XRD, SEM, void fraction, the average diameter of the pores, and the ability to withstand mechanical stress. Effluent from the desalter unit was synthesized in the laboratory using the salts most present in the desalter wastewater (NaCl, MgCl2, and CaCl2) and crude oil. This synthesized wastewater was treated with prepared ceramic membranes. It was discovered that different salt concentrations (0, 5000, 25,000, 50,000, 75,000, and 100,000 mg L−1) affected the permeate flux (PF), oil rejection, and ion rejection by the membrane. Results showed that in a lower concentration of salts (5000 and 25,000 mg L−1), PF of all types of ceramic membranes was increased significantly, while in the higher concentration, PF declined due to polarization concentration and high fouling effects. Oil and ion rejection was increased slightly by increasing salt dosage in wastewater due to higher ionic strength. Monovalent (Na+) and multivalent (Ca2+ and Mg2+) ion rejection was reported about 5 to 13%, and 23 to 40% respectively. Oil rejection varied from 96.2 to 99.2%.

Amphiphilic cellulose acetate membrane incorporated with MoS2 nanospheres for oil in water separation

“…Cations such as Mg 2+ and Ca 2+ accumulate around non-polar oil droplets and affect their surface charge, leading to their aggregation; therefore, the salt present in the oily wastewater will not negatively affect the efficiency of oil removal. 16,37…”