ABSTRACT
Water is an imperative source of life provided by nature, which is being overexploited throughout the world by human civilization or polluted by hydro-geological conditions. Surface or ground water resources are extensively used for supplying drinking water to urban and rural areas in India. Water bodies in arid or semi-arid regions are known to contain fluoride, iron, arsenic, nitrate, etc., which cause diseases like fluorosis, gastro-intestinal maladies, skin cancer, thyroid cancer and blue baby syndrome, respectively. Studies show that fluoride concentration in ground water can reach a maximum of up to 15 ppm on average in the Deccan Plateau of India. The ingestion of excessive fluorine into the human body affects the cell membranes and decreases the production of collagen which leads to bone disorders. Different water purification processes have been devised for the removal of contaminants, including fluoride, from raw and polluted water. This chapter provides an insight on a plethora of water purification technologies starting, which are either stand alone or retrofitted into existing processes. Technologies based on reverse osmosis (RO), nanofiltration (NF), and ultrafiltration (UF) of 50-1000 L/h capacities have developed to provide safe, clean and affordable drinking water to small habitats, schools, colleges and hospitals as well as largely populated villages. RO still remains one of the major solutions for removal of toxic elements from ground water, as demonstrated by a few case studies. On the other hand, highly compact and cost effective NF and UF pilot plants have been found to successfully process surface water into potable water at high recovery and low operating pressure, without the loss of minerals essential for human consumption. Capital investment and operating costs for the installed systems are discussed to project the efficacy of membrane systems. Treatment and reuse of an RO reject stream by different methodologies depending upon plant location is reported. By utilizing the various advantages associated with membrane-based separation processes, practical devices have been structured and found to operate effectively and competently to serve society as well as for the betterment of our environment. Design of hand-operated submerged membrane systems for installation in flood affected areas and remote villages which lack in power supply, along with the potential of hollow fiber membranes constitutes the future scope of work.
