Assessing the Performance of a Tubular Solar Still in an Arid Region Using Various Water Types

The performance of a tubular solar still in an arid region was evaluated for producing freshwater from various water sources. The water sources fed to the tubular solar still were blowdown from a seawater desalination plant, recovered water from an oil production facility, rejected seawater from a reverse osmosis treatment plant, seawater, and rejected groundwater from a reverse osmosis treatment plant. The TDS for these water sources ranged from 17,210 mg/L for groundwater to 221,710 mg/L for produced water. Compared with other water types, produced water had distinct characteristics: low pH, a petroleum-like odor, and a reddish-brown color. The estimated average production rates were 5.1, 5.9, 6.1, 6.6, and 6.8 L/m2·day for produced water, reverse osmosis-rejected water, desalination plant blowdown, seawater, and reverse osmosis-rejected groundwater. Different TSS designs were examined to determine whether production rates could be improved using tap water. Production increased slightly when a blackened basin, steel mesh, or both were applied as heat-absorption enhancements. Therefore, the tubular solar still without any enhancements was found to be a better option due to its lower cost and simpler design. The composition of the residual salts (65–73%) did not meet the 97% standard set by the FAO. The results of the study are promising for future upscaling projects aimed at enhancing water security in rural areas and arid regions.