Disinfectant
Disinfectants are antimicrobial agents that are applied to non-living objects to destroy microorganisms that are living on the objects. Disinfection does not necessarily kill all microorganisms, especially resistant bacterial spores; it is less effective than sterilization, whic…
Why does chlorine react vigorously with water?
Chlorination is the process of adding chlorine to drinking water to kill parasites, bacteria, and viruses. Different processes can be used to achieve safe levels of chlorine in drinking water. Using or drinking water with small amounts of chlorine does not cause harmful health effects and provides protection against waterborne disease outbreaks.
What is advantage and disadvantage of chlorine?
Chlorine reacts with organic matter to disinfection byporducts, such as trihalomethanes (THM) and halogenated acetic acids (HAA). Chlorine can be added for disinfection in several different ways. When ordinary chlorination is apllied, the chlorine is simply added to the water and no prior treatment is necessary.
Why does the water supply industry use chlorine?
Chlorination is a water treatment process that is used to eliminate certain pathogens, particularly in drinking water, such as dysentery and typhoid. Water treatment processes such as coagulation, filtration and sedimentation are used to battle waterborne diseases. For over a century, however, chlorination has been used to create water that is ...
Why is too much chlorine in pools so dangerous?
Jun 18, 2020 · In respect to this, how does chlorine work in water treatment? Chlorine kills pathogens such as bacteria and viruses by breaking the chemical bonds in their molecules. Disinfectants that are used for this purpose consist of chlorine compounds which can exchange atoms with other compounds, such as enzymes in bacteria and other cells.
See more
May 04, 1998 · Chlorine and chlorine-based compounds are the only disinfectants that can efficiently kill microorganisms during water treatment, and maintain the quality of the water as it flows from the...
How is chlorine used in water treatment?
To prevent contamination with germs, water companies add a disinfectant—usually either chlorine or chloramine—that kills disease-causing germs such as Salmonella, Campylobacter, and norovirus.
What happens when chlorine is added to water?
Chlorine will react in water to form hypochlorous acid, which can then dissociate into hydrogen and hypochlorite ions, according to Eqn (1). This reaction is very important, as the disinfecting power of HOCl, hypochlorous acid, is about 40–80 times that of OCl−, hypochlorite.
How does chlorination system work?
Metering pumps are used to inject a small amount of chlorine (sodium hypochlorite solution, or calcium hypochlorite solution) into the water, usually in conjunction with a contact tank. The pumps draw chlorine bleach from a solution tank and pump it into a pipe under pressure.
Can chlorine in drinking water be harmful?
Is Chlorine in My Drinking Water Dangerous? At the concentrations found in drinking water, chlorine is nontoxic to humans. Many municipalities add chlorine to their water to help kill harmful organisms such as viruses and bacteria that could make us sick if we ingested them.
How much chlorine should I add to drinking water?
To disinfect water, add one part of the chlorine solution to each 100 parts of water you are treating. This is about the same as adding 1 pint (16 ounces) of the chlorine solution to 12.5 gallons of water.Dec 9, 2021
Why is chlorine added to water?
Drinking water chlorination is the addition of chlorine to drinking water systems. It is the most common type of drinking water disinfection. Disinfection kills bacteria, viruses, and other microorganisms that cause disease and immediate illness.Apr 4, 2019
How do you inject chlorine into water?
0:272:49The Evolution of Chlorine Injection Systems - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd from there we would run it through a carbon filter to take chlorine out again the overall goalMoreAnd from there we would run it through a carbon filter to take chlorine out again the overall goal of injecting chlorine in the water is to kill bacteria.
What is chlorine used for in disinfection?
Chlorine reacts with organic matter to disinfection byporducts, such as trihalomethanes (THM) and halogenated acetic acids (HAA). Chlorine can be added for disinfection in several different ways. When ordinary chlorination is apllied, the chlorine is simply added to the water and no prior treatment is necessary.
How is chlorine broken down?
Chlorine is broken down under the influence of sunlight. UVradiation in sunlight provides energy which aids the break-down of underchloric acid (HOCl) molecules. First, the water molecule(H2O) is broken down, causing electrons to be released which reduce the chlorine atom of underchloric acid to chloride (Cl-).
What is the pH of water for disinfection?
The effectivity of disinfection is determined by the pH of the water. disinfection with chlorine will take place optimally when the pH is between 5,5 and 7,5. underchloric acid (HOCl) reacts faster than hypochlorite ions (OCl-); it is 80-100% more effective. The level of underchloric acid will decrease when the pH value is higher.
How is chlorine produced?
Finally, chlorine can be produced by means of molten salts electrolysis and, mainly in laboratories, by means of hydrochloric acid and manganesedioxide oxidation: MnO2+ 4HCl -> MnCl2+ 2H2O + Cl2. When gaseous chlorine is added to water the following hydrolysis reaction takes place: Cl2+ H2O = H++ Cl-+ HOCl.
What disinfectant is used for water disinfection?
Concentrations- Effectivity- Health Effects- Legislation. Chlorine. Chlorineis one of the most commonly used disinfectants for water disinfection. Chlorine can be applied for the deactivation of most microorganisms and it is relatively cheap.
How many electrons does chlorine have?
It can also cause an extra eletron to form (a covalent bond; a chlorine bond), causing the outer shell to complete. Figure 2: chlorine atoms contain 17 electrons. Chlorine can form very stable substances, such as kitchen salt (NaCl). Chlorine can also form very reactive products, such as hydrogenchloride (HCl).
How much chlorine is needed to kill bacteria?
To kill bacteria little chlorine is required; about 0,2-0,4 mg/L. the concentrations of chlorine added to the water are usually higher, because of the chlorine enquiry of the water. Nowadays chlorine gas is only used for large municipal and industrial water purification installations.
What is chlorination in water?
Chlorination is a water treatment process that is used to eliminate certain pathogens, particularly in drinking water, such as dysentery and typhoid. Water treatment processes such as coagulation, filtration and sedimentation are used to battle waterborne diseases. For over a century, however, chlorination has been used to create water ...
What is chlorine used for?
Chlorine is most commonly used in water treatment for as a disinfectant, though seldom in its pure form. Chlorine gas, sodium hypochlorite and calcium hypochlorite are the three most common chlorine compounds used in water treatment.
What is the role of calcium hypochlorite in food?
Calcium hypochlorite also plays a major role in industrial food processing, killing germs and keeping our food supplies safe. For example, if you have water stored in a large tank, adding the right about of calcium hypochlorite with the help of a chlorination system will help disinfect the water.
What is the most common compound used in water treatment?
Calcium hypochlorite: Chlorine hypochlorite is the most common compound of chlorine used in residential water treatment. Calcium hypochlorite increases the pH of the water it is being used to treat and can be sold as calcium hypochlorite pellets or granules. Calcium hypochlorite should also be handled with care as it is capable ...
What happens during the disinfection stage of water treatment?
During the disinfection stage of the water treatment process – most of the time, chlorination occurs at this stage. Coagulation: untreated water enters the treatment plant and liquid aluminium sulphate is added, causing tiny dirt particles in the water to stick together.
When was chlorine first used in water?
The use of chlorine in water treatment has been around since 1893 and permanent water chlorination began in 1905. Hamburg, Germany was the first to attempt chlorinating drinking water, shortly followed by Maidstone, England, as a way to make water completely germ-free.
When is chlorination performed?
Chlorination can also be performed during any part of the water treatment process, including: Pre-chlorination – almost immediately after water enters the treatment facility. After sedimentation and prior to filtration. During the disinfection stage of the water treatment process – most of the time, chlorination occurs at this stage.
How long does it take for chlorine to react with water?
This reaction time is called the contact time. For most water systems, the best contact time is usually 30 minutes. To ensure continued protection against harmful organisms, a certain amount of chlorine must remain in the water after treatment. The remaining chlorine is known as a residual chlorine.
When did chlorine start in drinking water?
Health officials began treating drinking water with chlorine in 1908 . Previously, typhoid fever had killed about 25 out of 100,000 people in the U.S. annually, a death rate close to that now associated with automobile accidents. Today, typhoid fever has been virtually eliminated.
What disinfectant kills microorganisms?
Chlorine and chlorine-based compounds are the only disinfectants that can efficiently kill microorganisms during water treatment, and maintain the quality of the water as it flows from the treatment plant to the consumer's tap.
What are the possible sequence of events during chlorination?
A possible sequence of events during chlorination would be: disruption of the cell wall barrier by reactions of chlorine with target sites on the cell surface. release of vital cellular constituents from the cell. termination of membrane-associated functions. termination of cellular functions within the cell.
What is the reaction of chlorine to biomolecules in bacteria?
Researchers postulated that chlorine, which exists in water as hypochlorite and hypochlorous acid, reacts with biomolecules in the bacterial cell to destroy the organism. Further work led to the so-called "multiple hit" theory of chlorine inactivation.
What is the problem with chlorinated water?
One concern with chlorinated water is its tendency to form trihalomethanes (THMs), carcinogenic by-products of the disinfection process. In 1979, the EPA adopted the THM regulation, limiting their allowable level in drinking water supplies.
Does chlorine affect gram negative bacteria?
Recently, though, scientists have studied how chlorine affects the cell walls of "gram-negative" bacteria, organisms including those causing typhoid fever, dysentery, cholera and Legionnaires' disease. By definition, gram-nega tive bacteria possess cell walls that consist of an outer membrane and a cytoplasmic membrane.
What is chlorine used for?
Chlorine is the chemical most often used to keep swimming pools and Jacuzzis free of bacteria that can be hazardous to humans. Chlorine kills bacteria though a fairly simple chemical reaction. The chlorine solution you pour into the water breaks down into many different chemicals, including hypochlorous acid (HOCl) and hypochlorite ion (OCl - ).
Is chlorine harmful to humans?
You have to keep adding chlorine to the pool as it breaks down. While the bacteria-killing properties of chlorine are very useful, chlorine also has some side effects that can be annoying to humans, and possibly even hazardous.
The process of purification and purification of water
As we saw in previous articles, the purification of water , according to its origin, state and destination is carried out in treatment plants . In these treatment stations, the disinfection phase tries to eliminate the bacterial load from the water, with all those microorganisms that have survived the previous processes.
How Chlorine in Drinking Water Affects Health
According to the doctor of Medicine Josep Lluís Berdonces , who is based on different studies on this subject, the chlorination of water can have harmful effects on people’s health. The disinfection process is usually done with two main compounds, chlorine and monochloramine.
Very low doses of chlorine are consumed
The problem with chlorine in human consumption is that, in daily practice, people are exposed to these chemical components in very low doses, but for very long periods of time (many decades, in the vast majority of cases).
Alternatives to water chlorination
All this confirms that the amount of residual chlorine present in drinking water must be constantly controlled by the authorities in charge of it, since there is numerous evidence of possible adverse effects on health.
Why is chlorine used as a disinfectant?
Chlorine and pH. In general terms, the lower the pH of the water, the more effective chlorine is as a disinfectant. Again, speaking generally, a reason for dosing effectively is that chlorination raises the pH of water, so overdosing often raises the pH to levels where chlorine does not work effectively as a disinfectant.
How much chlorine is needed for disinfection?
Residual requirements vary, but typical residual goal would be for 0.2 to 1 mg/L. In addition to disinfection, chlorine can be effectively used to oxidize iron, manganese and hydrogen sulfide to facilitate their removal, to reduce color in water, and to aid in such treatment processes as sedimentation and filtration.
What is the best way to disinfect water?
Other methods of disinfection such as ultraviolet and ozonation are effective disinfectants but they do not provide a residual to prevent pathogen regrowth as chlorination does. When treatment plants are distant from the point of use, chlorination is the best way to provide safe water to the end user. Municipal water providers usually rely on measurements of “chlorine residual”—the amount of chlorine remaining in the water after it reaches its destination—as proof of safety. Residual requirements vary, but typical residual goal would be for 0.2 to 1 mg/L.
What is calcium hypochlorite?
Calcium hypochlorite is manufactured from chlorine gas. It is best known as chlorine pellets and granules in residential water treatment. It is a white solid with a very pungent odor and it can create enough heat to explode, so it must not be stored near wood, cloth or petroleum products. Calcium hypochlorite increases the pH of the water being treated.
What is the best way to provide safe water to the end user?
When treatment plants are distant from the point of use, chlorination is the best way to provide safe water to the end user. Municipal water providers usually rely on measurements of “chlorine residual”—the amount of chlorine remaining in the water after it reaches its destination—as proof of safety. Residual requirements vary, but typical residual ...
Which is more effective for disinfecting: chlorine or hypochlorite?
Chemically, this has to do with the relationship between the two constituents of chlorine that together are often referred to as “free chlorine”—hypochlorus acid and hypochlorite ions. Hypochlorus acid is the more effective disinfectant and it dominates at lower pH levels, so a lower pH is preferred for disinfection.
Which is the least expensive chlorine?
Chlorine gas, which is actually sold as an amber-colored compressed liquid, is the least expensive form of chlorine and is, consequently, the preferred type for municipal water systems.
