Electrodialysis for fluoride and nitrate removal from synthesized photovoltaic industry wastewater-toward high performance experimental parameters

Abstract

This study focuses on the use of electrodialysis (ED) process as a mean to treat contaminated ultra-pure water (UPW) from the photovoltaic (PV) industry, for the elimination of two major ions pollutants that are fluoride and nitrate ions. Synthetic solutions, simulating contaminated UPW from the PV cells rinsing step, were used. Both ions were eliminated significantly after 15 min of treatment time with an initial concentration of 140 mgL−1, and 33 min with an initial concentration of 1000 mgL−1 for fluoride and nitrates ions, respectively. The study of the competition between these two ions in their eliminations showed that the presence of fluorides does not disturb the elimination of nitrates (no competition), while the presence of nitrates in the solution strongly affects the elimination of fluorides by delaying the treatment time from 15 to 53 min. In addition, the concentrations of pollutants in the treated solutions are lower than the standards recommended by the World Health Organization (WHO); consequently, the treated UPW can be reused in the process to achieve near Zero Liquid Discharge (ZLD). From a techno-economic standpoint, the ED technique under these experimental conditions could reduce the production price of photovoltaic cells. In effect; the total investment can be amortized in a few years, making this water treatment a viable alternative since UPW is expensive and its consumption is very important in this industry.