Evaluation of Distillate Quality Produced by Using a Hybrid Solar Desalination System

Purification of saline water through desalination has become paramount important to solve global water scarcity. Thus, prompting the need to critically evaluate the quality of desalinated water. The novelty of this study focuses on critically evaluating the quality of distillate from solar desalination systems when they are operated using solar radiation only, the use of only temperature, and the combined use of temperature and solar radiation. To achieve this a novel hybrid solar desalination system (HSDS) was designed and fabricated to operate in the mentioned three modes of operation. Ten water quality parameters (salinity, turbidity, TDS, TSS, ammonia, nitrate, COD, BOD, faecal coliform, and total coliform) were investigated under the three operation modes. The maximum daily distillate quantity when solar radiation only, the temperature only, and their combination were used are 4.7 L/m2.day, 19.7 L/m2.day, and 20.3 L/m2.day respectively. The results were compared with other similar research to check how operation conditions, feedwater source, and modifications in the solar still can affect distillate quality. The results revealed that the distillate obtained from the use of only temperature without sunshine has the best distillate quality with a total pollutant removal efficiency of 88.14 %, followed by the combined mode of 80.03 % and lastly the solar irradiance only of 74.63 %. The results further showed that the effect of high temperature has more impact in desalinating saline water contrary to the belief that solar radiation is more effective. From the results, certain parameters are not fully treated, for example, BOD, ammonia, and nitrate. Hence, it is recommended to have a pre-treatment system incorporated into solar desalination systems.