Production of safe water. Preface.

Increased water demand from population and economic growth, environmental needs, changes in rainfall, flood and contamination are the major factors that will continue to create water shortage problems. It is estimated that about 70% of water is used for agricultural activities. The problem with agricultural activities is not only related to the consumption of a large volume of water for irrigation, but also the use of huge amounts of fertilisers, pesticides and other chemicals. Industry uses only 20% of the available water for use. The remaining 10% is consumed for daily use, although this greatly depends on the regions of the world. The existence of arsenic in water is of global concern because it is a serious threat to human health and many of its compounds are especially potential poisons. Elemental arsenic and arsenic compounds are classified as toxic and dangerous for the environment in the European Union directive 67/548/EEC. Arsenic contamination in ground and surface waters in the Western U.S. ranged from 80 to 15,000 lg/L, because of the abundance of geothermal activities in this region. In some countries such as China, Tibet, Mongolia, India, Bangladesh, Vietnam, Cambodia, Thailand, Taiwan, Argentine and Mexico, a large portion of water is contaminated with arsenic at levels from 100 to over 2,000 lg/L. There is serious arsenic poisoning in Bangladesh. It was estimated that approximately 57 million people are drinking groundwater with arsenic concentrations above the World Health Organization’s standard of 50 lg/L, which was the permissible level of arsenic concentration for the last 60 years. The WHO revised its recommendation in 1993 to a maximum level of 10 lg/L. The Safe Drinking Water Act required the EPA to revise its existing 50 lg/L standard for arsenic in drinking water. In 2001, the EPA adapted a new standard, and public water systems must comply with the 10-lg/L standard since 2003. The U.S. EPA estimates that 4,000 drinking water treatment systems might require additional treatment technologies for arsenic removal, since 5.4% of the community water systems using groundwater and 0.7% of them using surface water, exceed the 10-lg/L arsenic level. The treatment cost is expected to be higher for rural areas due to their smaller scale. Thus, there is a need to develop costeffective and alternative treatment technologies for the removal of arsenic to meet the new standards. According to the current development level, none of the available means are sufficient to fight the water N. Kabay (&) S. Anaç Ege University, _ Izmir, Turkey e-mail: nalan.kabay@ege.edu.tr