Water is the most vital compound for life on Earth, and drinking water is a key concern worldwide for the 21st century. All living things need clean, pollution-free water as a basic need. Water covers more than 71% of the earth’s surface, but only about 1% of it is drinkable according to international standards due to various pollutions. Sewage discharge from industries, agricultural pollution, urban wastewater, environmental and global changes are the main sources of water pollution. Even small amounts of heavy metals, dyes and microbes are dangerous to human health, aquatic systems and the environment.
Water purification is any process that improves water quality to make it suitable for a specific end use. End use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including safe restoration to the environment. Water treatment removes contaminants and undesirable components or reduces their concentration to make the water suitable for its optimal end use.
Processes involved in the removal of contaminants include physical processes such as settling and filtration, chemical processes such as disinfection and coagulation, and biological processes such as slow sand filtration.
In addition to physical and biological measures, chemical methods are used to reduce the discharge of pollutants and wastewater into water systems. Various chemical methods are used to convert the final products or remove contaminants for safe disposal of contaminants.
• Prechlorination to control algae and stop biological growth
Aeration with pre-chlorination to remove dissolved iron in the presence of relatively small amounts of manganese.
• Disinfection to kill bacteria, viruses and other pathogens using chlorine, ozone and ultraviolet rays.
Chemical filtration is a technique used to make industrial water suitable for use or drainage. Includes chemical precipitation, chemical disinfection, chemical oxidation, advanced oxidation, ion exchange and chemical neutralization.