4 - Water treatment by reverse and forward osmosis

Abstract

Notably, the human population has grown about tenfold over the past 300 years and nearly fourfold in just the past century, Increasing water pollution has put much pressure on water resources. For this reason, the need for water is increasing rapidly and current freshwater resources may not be able to meet all requirements. Hence, there is a need to develop economical methods of purifying freshwater or desalting seawater. Membranes have risen to the challenge and continue to perform efficiently as well as effectively, and have become a viable alternative to evaporation-based technologies for water treatment. The advent of asymmetric membranes with a high retention of low-molecular-weight organic compounds and good physical and chemical stability has enabled reverse osmosis (RO) to be used more widely on a commercial scale. Another membrane process, forward osmosis (FO), can also be used to desalinate saline water sources at a remarkably reduced cost. This chapter addresses the significant progress in the area of RO and FO for the desalination of water, the difference between various membrane processes, and the fundamentals of water treatment by RO and FO.