Reverse osmosis performance on stripped phenolic sour water treatment - A study on the effect of oil and grease and osmotic pressure


Technologies for water recycling within oil refineries have been gaining interest at an extensive rate due to the large volume of wastewater generated, high dependency of water and the progressive scarcity of this valuable resource. Phenols are part of a specific class of organic pollutants that have been contributing to a low-quality effluent in oil refineries due to their hazardous nature and strict environmental legislation associated. The reuse of stripped sour water within refineries is often blocked due to its rich phenolic content. This study evaluates the retention of phenols in refinery wastewater through reverse osmosis (RO) at its major source of emission, for water reclamation. The RO membrane selected exhibited rejections of up to 98% of phenols and 99% of both chemical oxygen demand (COD) and total organic carbon (TOC). Permeate quality remained intact despite flux decline caused by phenolic and hydrocarbon adsorption when the oil content, in the feed, reached 771 ppm. The effluent's low conductivity due to lack of salts led to minor osmotic pressure differences (less than 23 bar at a volume concentration factor of 3), therefore, showing appealing performances of reverse osmosis filtration. Characterization of all permeates obtained from cross-flow filtration experiments showed COD levels in line with water reuse quality standards for make-up water in cooling processes.



subject category

Environmental Sciences & Ecology


Bastos, PDA; Santos, MA; Carvalho, PJ; Crespo, JG

our authors


The authors would like to acknowledge the financial support from Galp and Fundacao para a Ciencia e a Tecnologia (Portugal) through the PhD grant PD/BDE/128604/2017 (Pedro D. A. Bastos) in a PhD project within an industrial environment and Doctoral Program in Refining, Petrochemical and Chemical Engineering (EngIQ). P. J. Carvalho also acknowledges FCT for a contract under the Investigador FCT 2015, contract number IF/00758/2015. This work was supported by the Associated Laboratory for Sustainable Chemistry-Clean Processes and Technologies-LAQV and CICECO -Aveiro Institute of Materials, which are financed by Portuguese national funds from FCT/MEC (UID/QUI/50006/2013 and UID/CTM/50011/2019) and co-financed by the ERDF under the PT2020 Partnership Agreement (POCI-01-0145-FEDER e 007265).

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