Characterization and mitigation strategies for inorganic scaling in reverse osmosis system treating brackish groundwater

Abstract

Water desalination has become a more effective and widespread technology for treating seawater and brackish water because of a shortage of freshwater resources in Morocco and the world. Reverse osmosis is a commonly used method for water desalination. Nevertheless, membrane fouling remains a serious problem facing this technique, including inorganic, organic, colloidal, and biofouling. This research aims to analyze the performance of reverse osmosis used on Souss Massa farm and solve the fouling issue by using the chemical and physical properties of feed, permeate, and reject water, thus the characterization of fouling deposited on the membrane. The fouling was characterized by several techniques, such as scanning electron microscopy coupled with energy dispersion X-ray spectroscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The analysis revealed that Ca²⁺, Na⁺, Cl^–, HCO₃^–, and SO₄^2– are the most dominant ions in the feedwater. The predicting scaling indices and the characterization results of the scale structure developed on the membrane surface revealed that it was mainly composed of calcium carbonate and silica saturated. Changing the antiscalant and the proposed cleaning protocol prevent scale formation in reverse osmosis membranes and help increase and improve TDS's rejection rate from 94.23 % to 97.04 %.