Energy cost prediction for chromium removal by nanofiltration membrane

Abstract

Abstract This paper aims to investigate the energy cost of eliminating Cr(VI) by nanofiltration membranes (NF). The modified pore flow model was utilized to predict the performance of NF membrane in terms of ion retention and water productivity. Then, the energy cost was estimated according to the obtained results from this model as well as available data from literature. The effect of feed flow, applied pressure, and temperature on energy cost were highlighted and thoroughly assessed. It is shown that high retention values can be achieved with relatively high energy cost. Nonetheless, energy cost of 0.04 $/m3 have been estimated for Cr retention less than 95 % at a pressure of 5 bar. It is also assessed that feed flow has a significant influence on energy cost relative to other operating parameters. In particular, increasing feed flow from 40 to 760 L/h leading the energy cost to be increased by twelve times. At high feed flow, however, energy cost can be largely reduced by applying pressure higher than 10 bar. It is concluded that high feed temperature is favored if there is no need for heating equipment.