Water treatment by reverse and forward osmosis

Notably, the human population has grown about ten-fold over the past 300 years and nearly four-fold in just the last century and increasing water pollution have obstinately put pressure on water resources. Due to this reason, the need for water is increasing rapidly and current fresh water 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 became a viable alternative to evaporation-based technologies for water treatment. The advent of asymmetric membranes having high retention of low-molecular-weight organic compounds and good physical and chemical stability has enabled reverse osmosis to be used more widely on a commercial scale. Another membrane process namely forward osmosis can also be used for the desalination of saline water sources at a remarkably reduced cost. This chapter addresses the significant progress in the area of reverse osmosis and forward osmosis for the desalination of water, difference between various membrane processes, fundamentals of water treatment by reverse osmosis and forward osmosis.