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water purification
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What is water purification?
Water purification is a process that eliminates undesirable chemical and biological contaminants from water to provide clean drinking water for public health and to meet the needs of medical, chemical, and industrial applications. Water purification happens on a large scale for cities and on a smaller scale for households.
Most industrialized countries treat water at water treatment plants to ensure compliance with regulations. The methods used depend on the plant's size and the severity of contamination. These methods have become standardized and include practices such as coagulation and disinfection to remove suspended particles, microorganisms, and algae. Disinfection is essential for preventing the spread of waterborne diseases.
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Why is clean water important for public health?
Clean water is essential for public health because it prevents the spread of waterborne diseases. Contaminated water can contain harmful microorganisms and chemicals that cause illnesses, such as diarrhea, which is a leading cause of death in children under five. Access to safe and reliable drinking water is crucial, as indicated by the World Health Organization (WHO) report that highlights 2.1 billion people lack access to safe drinking water. Water purification and treatment are necessary to remove harmful impurities, ensuring it is free of harmful microorganisms and chemicals, thus protecting community health.
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What are common methods used to purify water?
To protect public health, water purification methods aim to remove harmful microorganisms and chemicals, making water aesthetically acceptable and safe for consumption. Water treatment depends on the source quality, with surface water needing more treatment than groundwater.
Common methods include:
* Clarification Removes turbidity through coagulation and flocculation, where chemicals like alum cause nonsettling particles to form heavier masses called floc.
* Disinfection Destroys pathogens using chlorine, chloramines, ozone, or ultraviolet (UV) radiation. Chlorination is cost-effective, while UV radiation eliminates chemical handling but can be expensive.
* Filtration Utilizes membrane filtration systems like microfiltration, ultrafiltration, and reverse osmosis to remove particles, microbes, and dissolved inorganic compounds.
* Boiling Heating water to 100 °C (212 °F) destroys harmful microorganisms but does not eliminate chemical contaminants.4 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does untreated water affect people's health?
Untreated water poses significant health risks due to the presence of harmful microorganisms and chemicals. Contaminated water can transmit various pathogens, leading to waterborne diseases like diarrhea and Giardiasis. Chemical contaminants, including pesticides and toxic metals, can also cause health problems if present above certain concentrations.
The absence of proper water treatment affects billions globally, resulting in disease and mortality. Ensuring access to safe drinking water through effective purification methods is essential for public health.
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What role do governments play in providing safe drinking water?
Governments worldwide play a vital role in ensuring safe drinking water through the establishment and enforcement of water quality standards. These standards, set by local, national, or international agencies, define the maximum allowable concentrations of contaminants to safeguard public health.
To meet these standards, governments invest in water treatment plants and environmental infrastructure, which includes aqueducts, reservoirs, and desalination plants. They also engage in the regulation of water resources, promote conservation, and manage water supply systems. These actions protect human health, prevent waterborne diseases, and address water scarcity.
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How can communities help maintain water purity and protect public health?
Communities can help maintain water purity and protect public health by managing water resources to maximize social welfare and ecosystem functioning. Public education is key for water conservation, utilizing sound science for sustainable resource management. Water quality standards should be continually improved.
Repairing infrastructure, improving irrigation technologies, and setting water-use reduction targets are crucial. Municipal water systems must include storage, transmission, and treatment facilities. Treatment of water is essential to protect the health of the community. Water should be free of harmful microorganisms and chemicals. Protecting water from pollution from human activities is also important.
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water purification, process by which undesired chemical compounds, organic and inorganic materials, and biological contaminants are removed from water. That process also includes distillation (the conversion of a liquid into vapour to condense it back to liquid form) and deionization (ion removal through the extraction of dissolved salts). One major purpose of water purification is to provide clean drinking water. Water purification also meets the needs of medical, pharmacological, chemical, and industrial applications for clean and potable water. The purification procedure reduces the concentration of contaminants such as suspended particles, parasites, bacteria, algae, viruses, and fungi. Water purification takes place on scales from the large (e.g., for an entire city) to the small (e.g., for individual households).
Most communities rely on natural bodies of water as intake sources for water purification and for day-to-day use. In general, these resources can be classified as groundwater or surface water and commonly include underground aquifers, creeks, streams, rivers, and lakes. With recent technological advancements, oceans and saltwater seas have also been used as alternative water sources for drinking and domestic use.
Determining water quality
Historical evidence suggests that water treatment was recognized and practiced by ancient civilizations. Basic treatments for water purification have been documented in Greek and Sanskrit writings, and Egyptians used alum for precipitation as early as 1500 bce.
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In modern times, the quality to which water must be purified is typically set by government agencies. Whether set locally, nationally, or internationally, government standards typically set maximum concentrations of harmful contaminants that can be allowed in safe water. Since it is nearly impossible to examine water simply on the basis of appearance, multiple processes, such as physical, chemical, or biological analyses, have been developed to test contamination levels. Levels of organic and inorganic chemicals, such as chloride, copper, manganese, sulfates, and zinc, microbial pathogens, radioactive materials, and dissolved and suspended solids, as well as pH, odour, colour, and taste, are some of the common parameters analyzed to assess water quality and contamination levels.
Regular household methods such as boiling water or using an activated-carbon filter can remove some water contaminants. Although those methods are popular because they can be used widely and inexpensively, they often do not remove more dangerous contaminants. For example, natural spring water from artesian wells was historically considered clean for all practical purposes, but it came under scrutiny during the first decade of the 21st century because of worries over pesticides, fertilizers, and other chemicals from the surface entering wells. As a result, artesian wells were subjected to treatment and batteries of tests, including tests for the parasite Cryptosporidium.
Not all people have access to safe drinking water. According to a 2017 report by the United Nations (UN) World Health Organization (WHO), 2.1 billion people lack access to a safe and reliable drinking water supply at home. Eighty-eight percent of the four billion annual cases of diarrhea reported worldwide have been attributed to a lack of sanitary drinking water. Each year approximately 525,000 children under age five die from diarrhea, the second leading cause of death, and 1.7 million are sickened by diarrheal diseases caused by unsafe water, coupled with inadequate sanitation and hygiene.
Process
Most water used in industrialized countries is treated at water treatment plants. Although the methods those plants use in pretreatment depend on their size and the severity of the contamination, those practices have been standardized to ensure general compliance with national and international regulations. The majority of water is purified after it has been pumped from its natural source or directed via pipelines into holding tanks. After the water has been transported to a central location, the process of purification begins.
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Pretreatment
In pretreatment, biological contaminants, chemicals, and other materials are removed from water. The first step in that process is screening, which removes large debris such as sticks and trash from the water to be treated. Screening is generally used when purifying surface water such as that from lakes and rivers. Surface water presents a greater risk of having been polluted with large amounts of contaminants. Pretreatment may include the addition of chemicals to control the growth of bacteria in pipes and tanks (prechlorination) and a stage that incorporates sand filtration, which helps suspended solids settle to the bottom of a storage tank.
Preconditioning, in which water with high mineral content (hard water) is treated with sodium carbonate (soda ash), is also part of the pretreatment process. During that step, sodium carbonate is added to the water to force out calcium carbonate, which is one of the main components in shells of marine life and is an active ingredient in agricultural lime. Preconditioning ensures that hard water, which leaves mineral deposits behind that can clog pipes, is altered to achieve the same consistency as soft water.
Prechlorination, which is often the final step of pretreatment and a standard practice in many parts of the world, has been questioned by scientists. During the prechlorination process, chlorine is applied to raw water that may contain high concentrations of natural organic matter. This organic matter reacts with chlorine during the disinfection process and can result in the formation of disinfection by-products (DBPs), such as trihalomethanes, haloacetic acids, chlorite, and bromate. Exposure to DBPs in drinking water can lead to health issues. Worries stem from the practice’s possible association with stomach and bladder cancer and the hazards of releasing chlorine into the environment.