Document Type : Original Article
Department of Environmental Sciences and Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran
Department of Water, Wastewater and Environmental Engineering, Faculty of Civil, Water and Environmental Engineering, Shahid Beheshti University, Tehran, Iran
This study aims to provide a green process implementation method for treating brine in the desalination system of brackish water with two stages of reverse osmosis. In this study, real samples taken from the first and second stages of the brackish water reverse osmosis (BWRO) plant were utilized to assess the performance of innovative sequencing batch electrocoagulation reactors (SBERs) with complementary processes (addition of chemicals and antiscalants, settling, microfiltration, UV, and ultrafiltration). According to the measurements, the TDS of the brackish water taken from the aquifer ranged from 3,229 to 3,664 mg/L, whereas that of the first-stage RO brine was between 5,500 and 7,700 mg/L, that of the second-stage RO brine was between 9,500 and 10,600 mg/L, and that of tap water was between 278 and 408 mg/L. The results of the study showed that the average removal of TDS, hardness, and ions in direct current (DC) was higher than in alternating current (AC) and that for Al-Al electrodes is more than that for Al-Fe electrodes. For the samples that were taken from the brine to the second stage RO with a TDS level of 9423 mg/L (with an increase in pH to 9 and with a temperature of 11 °C), the amount of TDS removal was 14%, and the amounts of hardness and scaling ions like calcium, magnesium, and sulfate (the amount of sulfate in quantities above 1400 mg/L) were removed equal to 35.5, 29, 35, and 30%, respectively. The TDS can be successfully reduced by electrocoagulation and scale-forming precursor ions can be eliminated by combining electrocoagulation and chemical precipitation.
The results of the research showed that the third alternative was more advantageous than the others for the development phase of the desalination system under study after multiple options were analyzed technically, environmentally, and economically. The results of the research showed that the third alternative was more advantageous than the others for the development phase of the desalination system under study after multiple options were analyzed technically, environmentally, and economically.
This option will direct brackish water to two RO (one stage)/SBERs processes. The RO desalination plant's brine and the SBER effluent are then combined to provide industrial water or irrigation water for plants that can tolerate salt.
This method has been proposed as the best option for desalination system development because it reduces the total volume of rejected brine and increases the water supply (drinking, industrial, or agricultural).