In drinking water facilities, 12 percent sodium hypochlorite is a primary disinfectant. In the time that it takes to ship the chemical, it typically degrades to 11 percent. In the calculations of dosages or concentrations, 10 percent should be used as the starting point.
Full Answer
Is sodium hypochlorite safe in drinking water treatment?
Drinking water treatment plants use various forms of chlorine to inactivate pathogens, oxidize metals or metalloids and provide disinfection residual for distribution systems. Recent concerns of safety for chlorine gas and high strength sodium hypochlorite have made on-site generation of sodium hypochlorite an attractive option.
What is the use of hypochlorite?
Hypochlorite can be used to prevent algae and shellfish growth in cooling towers. In water treatment, hypochlorite is used to disinfect water. In households, hypochlorite is used frequently for the purification and disinfection of the house.
What percentage of sodium hypochlorite is used in disinfectants?
In drinking water facilities, 12 percent sodium hypochlorite is a primary disinfectant. In the time that it takes to ship the chemical, it typically degrades to 11 percent. In the calculations of dosages or concentrations, 10 percent should be used as the starting point.
Should I add sodium hypochlorite to my pool at night?
Ideally, you should add sodium hypochlorite to your pool at night. This time works better than doing it during the day because of the lack of energy from ultraviolet rays. Exposure to UV light degrades the sodium hypochlorite quickly since it’s a type of unstable chlorine.
How long does sodium hypochlorite last in water?
At normal pH (6-8), sodium hypochlorite can degrade substantially within 2-3 weeks. This shelf life is not adequate for use in the SWS, which requires that the hypochlorite remain at a high enough concentration to inactivate disease-causing organisms.
How is sodium hypochlorite used in water treatment?
Disinfectants Sodium hypochlorite. Sodium hypochlorite (NaOCl) is a compound that can be effectively used for water purification. It is used on a large scale for surface purification, bleaching, odor removal and water disinfection.
How long does sodium hypochlorite last?
After the six-month expiration date, the sodium hypochlorite in bleach begins to degrade, at a rate of about 20 percent per year. Ultimately, due to the reaction of unstable ions, sodium hypochlorite (3NaOCl) breaks down into salt (2NaCl) and sodium chlorate (NaClO3), which is soluble in water.
How long does calcium hypochlorite last in water?
Calcium Hypochlorite is only a few bucks and you can find it at swimming pool supply stores such as Deep Blue Pools and Spas . This is also referred to as pool shock. Keep in mind that when the granular calcium hypochlorite is made into the liquid chlorine solution it does have a shelf life of about 24 months.
Is sodium hypochlorite safe for drinking water?
Oxidation reactions are corrosive, and solutions burn skin. In addition, chlorination of drinking water with sodium hypochlorite can oxidize organic contaminants, producing trihalomethanes, which are considered carcinogenic and are subject to regulation.
How do you use hypochlorite?
Sodium Hypochlorite can be used for water purification, surface purification, bleaching, odour removal and water disinfection....Sweep and wash the surface to remove any debris.Dilute 1 part sodium hypochlorite with 5 parts water. ... Apply the solution and wait 45 minutes.More items...
How long does chlorine bleach last in water?
24 hoursWhen bleach and water are mixed together to create a cleaning or disinfecting solution, the solution is only good for 24 hours. The temperature of the water does not affect the cleaning or disinfecting abilities of the solution. After the 24 hours, the solution begins to lose needed disinfecting properties.
How much bleach do you add to drinking water?
Emergency Disinfection of Drinking WaterVolume of WaterAmount of 6% Bleach to Add*Amount of 8.25% Bleach to Add*1 gallon8 drops6 drops2 gallons16 drops (1/4 tsp)12 drops (1/8 teaspoon)4 gallons1/3 teaspoon1/4 teaspoon8 gallons2/3 teaspoon1/2 teaspoon1 more row
Does sodium hypochlorite lose strength?
Sodium hypochlorite does degrade over time. The degradation products are naturally occurring compounds. Sodium hypochlorite stability is adversely affected by increases in storage temperature, low pH, exposure to sunlight and some metals in solution.
How much hypochlorite do I mix with water?
Sodium hypochlorite: concentration and use: Recommended dilution 1:100 dilution of 5% sodium hypochlorite is the usual recommendation. Use 1 part bleach to 99 parts cold tap water (1:100 dilution) for disinfection of surfaces.
Can you drink water with calcium hypochlorite?
You can use granular calcium hypochlorite to disinfect water. Add and dissolve one heaping teaspoon of high-test granular calcium hypochlorite (approximately ¼ ounce) for each two gallons of water, or 5 milliliters (approximately 7 grams) per 7.5 liters of water.
What is difference between calcium hypochlorite and sodium hypochlorite?
Sodium hypochlorite solutions are clear, greenish to yellow liquids with an odor of chlorine. Calcium hypochlorite is a white solid that readily decomposes in water releasing oxygen and chlorine. It also has a strong chlorine odor.
Abstract
Household water treatment with chlorine can improve the microbiological quality of household water and reduce diarrheal disease. We conducted laboratory and field studies to inform chlorine dosage recommendations.
INTRODUCTION
Worldwide, approximately 663 million people lack access to an improved water source and an estimated 1.2 billion more rely on contaminated water sources ( Onda et al. 2012; WHO/UNICEF 2015 ). Household water treatment (HWT) can be a cost-effective means of improving drinking water quality ( Clasen et al.
METHODS
Using deionized water, white kaolin clay (Lion China Clay USP, Charles B. Chrystal Co., Larchmont, NY), and TOC stock solution (Hach, Loveland, CO), we manufactured 12 different representative 10-liter plastic containers of water (‘reactors’), with turbidity levels from 10 to 300 NTU and TOC concentrations from 0 to 25 mg/L ( Figure 1 ).
RESULTS
Temperature and pH were constant for all reactors during all time points, with a mean and standard deviation temperature of 19.4°C (0.5) and a mean and standard deviation pH of 7.54 (0.1) ( Table 1 ).
DISCUSSION
We conducted laboratory and field studies to further investigate the relationship between turbidity and chlorination efficacy to inform HWT with chlorination recommendations. In the laboratory work, we created reactors of varying turbidity (10–300 NTU) and TOC (0–25 mg/L addition), spiked the reactors with E.
CONCLUSIONS
Based on our results, we recommend that improved/low turbidity sources be dosed at 1.88 mg/L and used within 24 hours, while unimproved/higher turbidity sources be dosed at 3.75 mg/L and, if possible, consumed within 8 hours.
ACKNOWLEDGEMENTS
We would like to thank all the organizations and partners and individuals who assisted us in collecting the water from the sources in the 22 countries, as well as the Tufts Summer Scholars and Cataldo programs, which provided funding for Anya Kaufmann's time and laboratory research.
When to shock pool with sodium hypochlorite?
If you need to shock the pool before adding the sodium hypochlorite, it would be best to wait until dusk to get the best results.
What is the best way to store sodium hypochlorite?
Hydrochloric acid. Acid-based brick or concrete cleaners. Metals (including copper, nickel, cobalt, iron, aluminum, and carbon steel) Ideally, it would help if you stored sodium hypochlorite in airtight containers placed in well-ventilated areas.
What is the best pool cleaning solution?
Although you can choose between several pool sanitation chemicals to suit your cleaning needs, one alternative to sodium hypochlorite might stand out to you. Some people know it as “ calcium hypochlorite ,” while others know it as “bleaching powder.”
How hot does sodium hypochlorite get?
Sodium hypochlorite remains stable in cool storage areas in temperatures around or below 60°F. If you place it in hotter temperatures, its quality degrades. Same goes for other pool chemicals. Head over to my post on how to safely store pool chemicals for more details.
What is the chemical reaction between chlorine and water?
Sodium hypochlorite is a compound formed from a chemical reaction between chlorine gas, water, and sodium hydroxide solutions. People also refer to it as “liquid chlorine” or liquid bleach. Other characteristics include a yellowish tint and a robust chlorine odor. Its pH level ranges between 11 and 13. When so dium hypochlorite reacts ...
Why does sodium hypochlorite get degraded?
Exposure to UV light degrades the sodium hypochlorite quickly since it’s a type of unstable chlorine. Since daylight hours tend to increase as spring transitions to summer, the temperatures tend to peak the more prolonged the sun is out. During the day, your pool becomes a breeding ground for all types of germs and substances.
What happens when you ingest sodium hypochlorite?
When ingested, it causes severe corrosion and damage to your gastrointestinal tract, including your mouth, throat, and esophagus. It also leads to poisoning. It would be best to contact poison control in situations where somebody might ingest sodium hypochlorite.
What happens when sodium hypochlorite dissolves in water?
When sodium hypochlorite dissolves in water, two substances are formed that play a role in oxidation and the disinfection processes. These are hypochlorous acid and the less active hypochlorite ion. The pH of the water determines how much hypochlorous acid is formed.
What is the pH of sodium hypochlorite?
Sodium hypochlorite is a clear, slightly yellowish solution with a characteristic odor. As a bleaching agent it is usually a 5 percent sodium hypochlorite with a pH of about 11. More concentrated solutions (10 to 15 percent) have a pH of about 13. Sodium hypochlorite is unstable.
How is sodium hypochlorite made?
Sodium hypochlorite can be produced in two ways. One is by dissolving salt in softened water, resulting in a concentrated brine. This brine is then electrolyzed to form a sodium hypochlorite solution containing 150 grams of active chlorine per liter. During this reaction hydrogen gas is also formed. The chemical also can be produced by adding chlorine gas to caustic soda, producing sodium hypochlorite, water and salt.
Why does chlorine degrade over time?
Right after the sodium hypochlorite is added to water, chlorine levels decline because the chlorine is reacting with organic matter and microbes. After those reactions are complete, chlorine will slowly escape into the air as a gas. For this reason, free and total chlorine levels slowly degrade over time in a container.
What is the most common disinfectant for drinking water?
Chlorine is the most common disinfection method for drinking water in North America. It comes as chlorine gas, sodium hypochlorite or calcium hypochlorite. A small community approached Okefenokee Technical College for information on sodium hypochlorite disinfection. The community had been using chlorine gas and ammonia as primary ...
What is the active ingredient in bleach?
The community had been using chlorine gas and ammonia as primary and secondary disinfectants. Sodium hypochlorite (NaClO) is the active ingredient in commercial liquid bleach, which is commonly available in 6, 12 and 15 percent solutions.
How much does chlorine evaporate?
Chlorine evaporates at a rate of 0.75 gram per day of active chlorine from solution. Sodium hypochlorite disintegrates when heated or if it contacts acids, sunlight, certain metals, and poisonous and corrosive gases, including chlorine gas.
What happens when sodium hypochlorite dissolves in water?
When sodium hypo chlorite dissolves in water, two substances form, which play a role in for oxidation and disinfection. These are hypochlorous acid (HOCl) and the less active hypochlorite ion (OCl-).
What is hypochlorite used for?
It is also used to detoxify cyanide baths in metal industries. Hypochlorite can be used to prevent algae and shellfish growth in cooling towers. In water treatment, hypochlorite is used to disinfect water. In households, hypochlorite is used frequently for the purification and disinfection of the house.
How is hypochlorous acid made?
Hypochlorous acid is produced by the reaction of sodium hydroxide with chlorine gas. In water, the so-called 'active chlorine' is formed. There are various ways to use sodium hypochlorite. For on-site salt electrolysis, a solution of salt (NaCl) in water is applied. Sodium(Na+) and chloride (Cl-) ions are produced.
Why is sodium hypochlorite inactive?
When sodium hypochlorite is stored for a long time, it becomes inactive . Another advantage of the on site process is that chlorine lowers the pH and no other acid is required to lower pH. The hydrogen gas that is produced is explosive and as a result ventilation is required for expolsion prevention.
How much chlorine evaporates from a solution?
Chlorine evaporates at a rate of 0,75 gram active chlorine per day from the solution. Then heated sodium hypochlorite disintegrates. This also happens when sodium hypochlorite comes in contact with acids, sunlight, certain metals and poisonous and corrosive gasses, including chlorine gas.
Why does chlorine burn?
When there is too much chlorine in the water, this burns the body tissues, which causes damage to air tracts, the stomach and the intestines, the eyes and the skin. When sodium hypochlorite is used in swimming pools, it sometimes causes red eyes and it gives off a typical chlorine odor.
What is the pH of sodium hypochlorite?
If it is more concentrated, it contains a concentration 10-15% sodium hypochlorite (with a pH of around 13, it burns and is corrosive). Sodium hypochlorite is unstable.
What is hypochlorite solution?
Hypochlorite solutions (HSs), also called liquid chlorine, are widely used as disinfectants during drinking water treatment and distribution. However, the decomposition of the hypochlorite ion results in the formation of undesirable inorganic contaminants such as chlorite, chlorate, bromate and perchlorate. While HS decomposition cannot be completely avoided, it can be minimized through applying adequate practices during the purchasing, handling and storage of such solutions. This article presents the results of an investigation of the management of HS in water treatment plants (WTPs) in small municipalities. The data concerning HS management were acquired through field visits and semi-structured interviews with operators and managers of the small WTPs. The information gathered about HS management practices was compared to best management practice guidelines. Results show that practices involving HS differ between WTPs and that there are important gaps in the application of the existing HS management guidelines. The research revealed that the implementation of specific guidelines for the purchasing, handling and storage of HS is difficult for small WTPs due to the lack of human resources, expertise, and education, as well as a lack of infrastructure capacity.
Does WTP 7A mix aged HS with newly acquired HS?
The surveyed WTPs that use bulk HS have only one HS tank, which can complicate the ability to comply with that recommendation. Among the three WTPs that use bulk HS, only one (WTP 7A) does not mix aged HS with newly acquired HS. However, this is not done in this particular WTP for the purpose of meeting that recommendation. The operators empty the remaining volume of HS from the tank (the drums are then used for post-chlorination in WTP 7B) before the delivery of the new HS stock. This is necessary so that they are able to receive the minimum purchase volume of HS per order imposed by their supplier (lower volume orders lead to additional costs).
What is calcium hypochlorite used for?
Although still best known for swimming pool disinfection, calcium hypochlorite feeder systems are also used around the world in drinking water and wastewater systems, cooling towers, building water systems, and throughout the food and beverage industries.
What are the downsides of calcium hypochlorite?
A common downside of calcium hypochlorite use is the formation of precipitates (solid particles) of calcium deposits in systems that include pumping from a chlorine solution tank . Such deposits must be removed, which typically involves periodic tank cleaning. Deposits in the chemical feed lines and pumps can be reduced by routine flushing/cleaning ...
What are the risks of drinking water without disinfection?
Without adequate and reliable disinfection, consumers are at risk of contracting and spreading waterborne diseases caused by viruses, bacteria, and other microorganisms. Other drinking water treatment objectives include producing water that looks and tastes good and does not corrode pipes and household plumbing.
When was chlorination invented?
We recently celebrated the 110th anniversary of U.S. drinking water chlorination, a disinfection technology that debuted in Jersey City in 1908 using a dry compound called “chloride of lime.”. Today we more properly call it calcium hypochlorite.
Does chlorine kill bacteria?
Once inside the microbial cell wall, free chlorine wreaks havoc on bacteria, disrupting metabolic processes and causing rapid cell death. And unlike ozone or ultraviolet light, chlorine can provide lasting, residual (secondary) disinfection to help ensure safe storage and distribution of treated water to our homes, schools, and businesses.
Is calcium hypochlorite good for drinking water?
As noted previously, U.S. and international communities that use calcium hypochlorite for drinking water treatment and disinfection typically serve small (often very small) populations. The primary advantages are related to storage and feeding compared to chlorine gas or liquid bleach.
