Pretreatment process optimization and reverse osmosis performances of a brackish surface water demineralization plant, Morocco

In surface water reverse osmosis (RO) demineralization processes, pretreatment is a key step in achieving high performances and avoiding frequent membrane fouling. The plant studied includes conventional pretreatment and RO process. The aim of this study is the optimization of the coagulation–flocculation and the assessment of its effect on pretreated water quality upstream of the RO unit. The monitored parameters were turbidity, residual aluminum, and silt density index (SDI). Moreover, this paper presents the RO membrane performance in terms of feed pressure, pressure drop, permeate flow, and permeate conductivity after nearly 1 y of operation. The results obtained illustrate that the pretreatment optimization substantially reduces the residual aluminum concentration and the SDI after the 5 μm cartridge filters. Likewise, the RO membranes exhibited high and steady performance.