Innovative ceramic hollow fiber membranes for recycling/reuse of oilfield produced water

Abstract

The focus of this study was on the development and application of ceramic hollow fiber membrane (CHFM) technology for the treatment of oilfield produced water (PW) prior to disposal/discharge into the environment. PW refers to any fossil water that is brought to the surface along with crude oil or natural gas. It is a complex mixture of dispersed oil, dissolved organic compounds, suspended solids, production chemicals, heavy metals, and natural radioactive minerals. PW is difficult to handle/treat and represents the largest volume of waste associated with the oil and gas industry. It can have different potential impacts on offshore or onshore environments depending on where it is discharged. Therefore, the development of effective treatment technologies for PW is essential from both ecological and economic standpoints. The first stage of any treatment process for PW consists of a significant reduction in the level of dispersed hydrocarbons and suspended solids. In a second and often in a third stage, the oil and total carbon (TC) content is reduced by hydrocyclones and by micro- and ultrafiltration using membrane technologies. Due to legal requirements, final oil contents below 10 ppm are required in some regions before PW disposal to the environment. CHFMs represent a new generation in the development of inorganic membranes by offering the advantages of one membrane consisting of both inorganic material and hollow fiber geometry. In this study, the effect of cross-flow velocity on the CHFM performance at a low trans-membrane pressure of 0.5 bar, as well as the permeate quantity and quality, was investigated in terms of fouling behavior and efficiency of oil and TC removal. In the filtration system presented here, using ceramic hollow fiber ultrafiltration (UF) membranes with a d90 pore diameter of 40 nm, the removal of oil and TC from samples of tank dewatering produced water and oily model systems, was successfully demonstrated with a remarkable decontamination efficiency of >99.5% (oil) and 61–94% (TC), respectively.