Comparison of the performances of three commercial membranes in fluoride removal by nanofiltration. Continuous operations

Fluoride contamination of groundwater becomes more and more a worldwide preoccupation, especially in Morocco. With the decrease in water resources, especially underground water, and the frequent excess observed during these last decades, the dilution solution becomes unattainable in a short term. So to prevent this situation, the National Office of Potable Water (ONEP) has initiated studies in collaboration with Ibn Tofail University to investigate remedial options. The study on the comparison of the performances of electrodialysis and nanofiltration in the fluoride removal was started two years ago. In previous works, results of electrodialysis performances and preliminary results of nanofiltration performances have been presented. In this work, comparison of the performances of three commercial membranes in fluoride removal by nanofiltration in continuous mode was carried out. The pilot used (supplied by the French Company TIA, Techniques Industrielles Appliquees) is an industrial nanofiltration pilot plant having two modules equipped with various spiral commercial membranes with an area of 7.6 m2. Many configurations were tested: simple pass, double pass with one type of membranes and combination of two types of membranes and supplied batch configuration. The water parameters were followed as a function of the running conditions (time, pressure, fluoride content, etc.) in order to follow the behaviour of the membranes tested.