Chapter 4 - Solar-driven water treatment: generation II technologies

Abstract

Due to water and energy crises around the world, the use of solar-powered processes to supply drinking water in urban, rural, and remote areas has attracted much attention. Among these categories, desalination of seawater and brackish water seems a sustainable option in meeting drinking water needs. Desalination is the process of removing salt from water to produce drinking water. Most desalination techniques, including reverse osmosis and electrodialysis techniques, have high costs of construction, repair, and maintenance, and also they require consuming electrical power. In addition, their high capacities make these techniques unsuitable for areas with a dispersed population. Solar distillation is a promising alternative for these techniques. In this chapter the second generation of solar water treatment technologies, including solar water desalination in two direct and indirect methods, is comprehensively presented. Recent advances and applications of five major solar desalination technologies such as solar-powered humidification–dehumidification (HDH), multistage flash desalination (MSF), multieffect desalination (MED), reverse osmosis (RO), and solar stills have been comprehensively reviewed. In particular, solar stills have been described in detail as one of the oldest yet simplest methods of direct solar water desalination. Productivity, energy consumption, and water production costs of each of the different technologies are presented. Also, common methods of solar water disinfection have been reviewed as one of the common and low-cost methods of water treatment, especially in areas with no access to drinking water. Although desalination technologies have many benefits in social, economic, and public health aspects, they are energy-intensive and therefore have a detrimental effect on the environment. In addition, the disposal of waste from desalination processes is one of the most challenging and costly issues. In this regard, the environmental effects of desalination technologies are presented and discussed.