* Corresponding author. 1944-3994/1944-3986 © 2019 Desalination Publications. All rights reserved. Desalination and Water Treatment www.deswater.com doi: 10.5004/dwt.2019.24577 167 (2019) 231–244 November Removal of heavy metals by tight γ-Al 2 O 3 ultrafltration membrane at low pressure Majda Breida*, Saâd Alami Younssi, Mama El Rhazi, Mohamed Bouhria Department of Chemistry, Laboratory of Materials, Membrane and Environment, Faculty of Sciences and Technologies of Mohammedia, University Hassan II of Casablanca, P.O. Box: 146, Mohammedia 20650, Morocco, emails: breidamajda@gmail.com/ majda.breida-etu@univh2m.ma (M. Breida), alamiyounssisaad@yahoo.fr (S.A. Younssi), elrhazim@hotmail.com (M. El Rhazi), bouhria@yahoo.com (M. Bouhria) Received 25 February 2019; Accepted 16 June 2019 abstract The removal of chromate (Cr(VI)) and copper (Cu(II)) from water was investigated by using ultrafil- tration (UF) as a possible alternative to the conventional methods of metal ions removal. The influence of experimental parameters such as pH, pressure and concentration was investigated on different solutions (K 2 Cr 2 O 7 , CuSO 4 and Cu(NO 3 ) 2 ). The influence of salts’ presence (NaNO 3 and Na 2 SO 4 ), with different concentrations, on metal removal was studied. The rejection of Cr(VI) was found to be improved with the increase of pH (with high rejection of 97% at pH above 9), whereas for Cu(II) the best rejections were obtained at 2.60 (with high rejections of 80% and 50%, for Cu(NO 3 ) 2 and CuSO 4 ). The increase of the applied pressure causes an increase of metals’ rejections and fluxes. Furthermore, an insignificant polarization concentration phenomenon was observed. The Cr(VI) rejection was observed to be independent from the increase in concentration (>90% for all concentrations, ranging from 10 to 150 mg (Cr(VI))/L) and a decrease in rejection with increasing concentration was observed for copper salts. The permeate flux was found to be lower at higher feed concentration, but varied only marginally with change in pH value. The metals’ retentions depend strongly on the solute type (including charge valency and hydration energy). The γ-Al 2 O 3 UF was found to be an efficient process to remove/recover heavy metals from industrial discharges. Keywords: Chromium; Copper; Heavy metal contamination; γ-Al 2 O 3 ; Ultrafiltration; Metalworking industries 1. Introduction Water is the bloodstream of the biosphere and it is equally fundamental for humans and ecosystems. Consequently, the evolution of an economy is strongly dependent on our future patterns of water use. This evolution of economy has major (direct and indirect) implications on water [1]. According to Calzadilla et al. [2], nearly one in three peo- ple live in areas of moderate to high water stress and it is estimated that two-thirds of population could be living under water-stressed conditions by 2025 [3]. The increase of water problem with wastewaters primarily entails with the continuous development of the different industrial sectors [4,5]. The process wastes from industries such as ceramics, plating, glass, battery manufacturing and mining are con- sidered as the primary sources of groundwater contamina- tion by heavy metals [6,7]. In fact, metal can be classified as a heavy metal when it is toxic at low concentrations and has a high density that is five times bigger than that of water [8,9]. Unlike organic pollutants, heavy metals are persistent contaminants, not biodegradable, with high solubility, high toxicity, and have the ability to accumulate in living organisms. In fact, the toxicity caused by heavy metal con- tamination is strongly dependent on the chemical form of the metal in question. Out of the existing heavy metals, Cr and its derivatives are used in a wide variety of industrial