Nanofiltration process combined with electrochemical disinfection for drinking water production: Feasibility study and optimization

Abstract In 2014, the first nitrate removal plant, using nanofiltration (NF) coupled to an electrochemical disinfection system, supplied with renewable energies (Photovoltaic and wind energies) was realized at Al Annouar high school of Sidi Taibi (Kenitra, Morocco). This project was designed to supply the 1200 students of the school with potable water, based on the production capacity of 500 L/h (3 L/Day/student). The local underground water, which is slightly brackish and nitrated, was treated by nanofiltration, using a hybrid renewable energy system, photovoltaic and wind; just before the distribution, an electrochemical disinfection setup was used to disinfect the nanofiltered water. In the first part of this work, the feasibility of the processes combination (nanofiltration- electrochemical water disinfection step) is verified by assessing the main factors which have determined the electrolysis performance (Volumetric flow rate, temperature, chloride concentration, energy…). This part of the study is carried out during two years of operation (from April 2014 to February 2016). The second part focused mainly on the optimization of a new membrane treatment plant. The purpose of this installation is twofold; firstly, the objective was to correct the concentration of chloride ions at the inlet of electrolysis. Secondly, it was meant to avoid the quality deterioration of the produced water (nitrates in particular). The results of this study confirmed the feasibility of the process combination: nanofiltration and electrochemical water disinfection, especially with the use of renewable energies (Photovoltaic and wind). On other hand, this installation will be more attractive by blending raw water with the nanofiltered water in order to increase the performances of the plant hydraulically, energetically, and to correct the chloride concentration for safe disinfection of water. Hence, the produced water by the new installation (process bypass blending) is totally mineral for human consumption and slightly corrosive for pipes and equipments.