Using Solar Evaporation Ponds for the Treatment of the Desalination Plants Brine

Abstract

In this research, An experimental shallow solar pond (SSP) having a surface area of 1*1 m2 and depth of 20 cm has been built. Solar evaporation ponds are especially suitable to dispose of reject brine from inland desalination plants in arid and semi-arid areas due to the abundance of solar energy. Nearly all forms of salt production require evaporation of water to concentrate brine and ultimately produce salt crystals. In this study, three scenarios have been used (1): Solar pond without using any mirror in 17 July 2015, (2): Solar pond using one reflector mirror; this scenario extending for five days from 18 to 22 July 2015, (3): Solar pond using two reflector mirrors extending for five days from 12 to 16 July 2015. Mirrors, which are movable for five different angles that makes with horizontal, have been used as reflectors in order to increase the thermal energy for the surface of the solar pond during the day. This research has been studied the main factors affecting the evaporation rate which are relative humidity, wind speed, ambient air temperature and solar radiation. The results showed that the little of decreasing evaporation rate was observed by increasing relative humidity and maximum evaporation rate was observed at relative humidity of 67.6%, while slight increasing of evaporation rate was observed by increasing ambient air temperature, evaporation rate appears to decrease slightly as wind speed increases and gradual increasing of evaporation rate with increasing solar radiation. Comparisons between experimental and theoretical results have been performed which good agreement has been achieved. Results showed that evaporation rate increases with decreasing the mirror's angle that makes with horizontal β. It was concluded that using two mirrors are very effective more than using one mirror when they are used as reflectors and that the best performance of the evaporation can be achieved when the mirrors are employed as reflectors. In conclusion, this system proved to be promising and using one mirror and two mirrors reduced the solar pond area and hence reduced area needed for brine evaporation in Gaza strip desalination plants then can be further developed to achieve better results using large scale solar pond.