Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for human consumption, but water purification may also be carried out for a variety of other purposes, including medical, pharmacological, chemical, and industrial applications. The history of water purification includes a wide variety of methods. The methods used include physical processes such as filtration, sedimentation, and distillation; biological processes such as slow sand filters or biologically active carbon; chemical processes such as flocculation and chlorination; and the use of electromagnetic radiation such as ultraviolet light.
Water treatment is any process that improves the quality of water to make it appropriate for a specific end-use. The end use may be drinking, industrial water supply, irrigation, river flow maintenance, water recreation or many other uses, including being safely returned to the environment. Water treatment removes contaminants and undesirable components, or reduces their concentration so that the water becomes fit for its desired end-use. This treatment is crucial to human health and allows humans to benefit from both drinking and irrigation use.
Ultrafiltration (UF) is a variety of membrane filtration in which forces such as pressure or concentration gradients lead to a separation through a semipermeable membrane. Suspended solids and solutes of high molecular weight are retained in the so-called retentate, while water and low molecular weight solutes pass through the membrane in the permeate (filtrate). This separation process is used in industry and research for purifying and concentrating macromolecular (103–106 Da) solutions, especially protein solutions.
Microfiltration is a type of physical filtration process where a contaminated fluid is passed through a special pore-sized membrane filter to separate microorganisms and suspended particles from process liquid. It is commonly used in conjunction with various other separation processes such as ultrafiltration and reverse osmosis to provide a product stream which is free of undesired contaminants.
A water filter removes impurities by lowering contamination of water using a fine physical barrier, a chemical process, or a biological process. Filters cleanse water to different extents, for purposes such as: providing agricultural irrigation, accessible drinking water, public and private aquariums, and the safe use of ponds and swimming pools.
Sand filters are used as a step in the water treatment process of water purification.
Water supply and sanitation in Hong Kong is characterized by water import, reservoirs, and treatment infrastructure. Though multiple measures were made throughout its history, providing an adequate water supply for Hong Kong has met with numerous challenges because the region has few natural lakes and rivers, inadequate groundwater sources, a high population density, and extreme seasonable variations in rainfall. Thus nearly 80 percent of water demand is met by importing water from mainland China, based on a longstanding contract. In addition, freshwater demand is curtailed by the use of seawater for toilet flushing, using a separate distribution system. Hong Kong also uses reservoirs and water treatment plants to maintain its source of clean water.
Manila Water Company, Inc. has the exclusive right to provide water and used water (wastewater) services to over six million people in the East Zone of Metro Manila. It is a subsidiary of the country's oldest conglomerate, Ayala Corporation.
Dallas Water Utilities (DWU) is the water and wastewater service operated by the City of Dallas, Texas, in the United States. DWU is a non-profit City of Dallas department that provides services to the city and 31 nearby communities, employs approximately 1450 people, and consists of 26 programs. DWU's budget is completely funded through the rates charged for water and wastewater services provided to customers. Rates are based on the cost of providing the services. The department does not receive any tax revenues. Primary authority and rules for the department are listed in Chapter 49Archived 2006-10-04 at the Wayback Machine of the Dallas City Code.
The Bare Point Water Treatment Plant is the primary water filtration plant in the city of Thunder Bay, Ontario, drawing 113.6 million litres from Lake Superior per day. The plant uses a Zeeweed 1000 Version 3 Ultra-Filtration system, the first of its kind in the world, which reduces the need for harmful chemicals. The Zeeweed system uses long thin straws that suck up water then force it through the small holes of a membrane to filter out particles.
Reverse osmosis (RO) is a water purification process that uses a semi-permeable membrane to separate water molecules from other substances. RO applies pressure to overcome osmotic pressure that favors even distributions. RO can remove dissolved or suspended chemical species as well as biological substances, and is used in industrial processes and the production of potable water. RO retains the solute on the pressurized side of the membrane and the purified solvent passes to the other side. It relies on the relative sizes of the various molecules to decide what passes through. "Selective" membranes reject large molecules, while accepting smaller molecules.
Degrémont is a company specializing in the production of drinking water, and in the treatment of sewage and sludge. After starting as a family business in France in 1939, it has since become a subsidiary of Suez Environment, employing 4,600 people in 70 countries, and generating annual revenues of €1.520 billion.
Raw water is water found in the environment that has not been treated and does not have any of its minerals, ions, particles, bacteria, or parasites removed. Raw water includes rainwater, ground water, water from infiltration wells, and water from bodies like lakes and rivers.
Jeyranbatan reservoir is a reservoir in the Absheron Rayon in eastern part of Azerbaijan. It is located between Baku and Sumgayit cities, next to Ceyranbatan settlement 20 km from Baku. In Azerbaijani language Jeyranbatan means "the place where the gazelle has drowned" which refers to an ancient legend related to the naming of city of Sumgayit.
The Nemmeli Desalination Plant is a water desalination plant at Nemmeli, Chennai, on the coast of the Bay of Bengal that supplies water to the city of Chennai. Initially the desalination plant experienced operational issues since the beginning and was shut down most of the time as contractor had installed the desalination plant without dissolved air floatation units leading to severe and regular choking of filters. It is located about 35 km south of the city centre, along the East Coast Road. Built at a cost of ₹ 5,333.8 million, the plant is the second desalination plant in the city after the 100-MLD plant at Minjur and itself has a capacity to treat 100 million litres of seawater a day.
National Policy Dialogues on Integrated Water Resources Management in Azerbaijan for managing water resources are aimed at developing a state strategy based on "Convention on the Protection and Use of Transboundary Watercourses and International Lakes" of United Nations Economic Commission for Europe and European Union Water Framework Directive and the "Water and Health" Protocol of that convention as well as other principles of the United Nations and the EU.
The Walton water treatment works are an advanced purification works supplied with raw water and producing and delivering potable water to the locality and into the Thames Water ring main. The Walton water treatment works were initially built in 1907 north of the Bessborough and Knight reservoirs which supply the water works.
Gulu Water Supply and Sanitation Project (GWSSP), also Gulu Water Supply and Sewerage System, is a water intake, purification, distribution and waste water collection and disposal system in the city of Gulu, the largest urban centre in the Northern Region of Uganda. In October 2020, the Uganda government concluded Phase 1 of the improvement of water supply and sanitation in the city, with funding from the World Bank, KfW and the Government of Uganda. Phase 2 improvements are expected to start in 2021, with funding from the World Bank, KfW and the Commonwealth Development Corporation.
Masaka–Mbarara Water Supply and Sanitation Project (MMWSSP), is a water intake, purification, distribution and waste water collection and disposal system in the cities of Masaka and Mbarara in the Central Region and the Western Region of Uganda. The project is intended to meet the water supply and sanitation needs of approximately 1,055,000 by 2030. The work is to be carried out by the Uganda Ministry of Water and Environment through the parastatal utility company, National Water and Sewerage Corporation (NWSC). Funding, have been provided by the French Development Agency and the European Union.
The Coppermills Water Treatment Works is a large water treatment works in the Lea Valley in east London. Completed in 1969 by the Metropolitan Water Board, it is now owned and operated by Thames Water. In 2009, Coppermills was connected to the Thames Water Ring Main via the Northern Extension Tunnel, enabling the facility to be a major supplier of water to the whole London area. It is capable of supplying a maximum of 680 million litres of water per day.
