What is the important of chlorine in water treatment?
What are the sources of water pollution?
- Industrial waste. Every day, industries produce large amounts of waste. …
- Wastewater and sewage. …
- Marine Dumping. …
- Oil Spills. …
- Pesticides and chemical fertilizers. …
- Sewage and wastewater treatment. …
- Protect large water bodies. …
- Reduction of water as a coolant in power plants and industries.
Why is chlorine used for water treatment?
- Total global chlorine production = 55,551,000 tonnes
- Total US chlorine production = 11,956,000 tonnes
- Total US consumption for water treatment = 615,000 tonnes
- Total European Community chlorine production = 10,870 tonnes
- Total European Community consumption for water treatment = 270,000 tonnes
How is the water treated in a water treatment plant?
- Makeup water intake. As water circulates through a cooling tower system, a portion is lost to evaporation, bleed to drain, and leaks. ...
- Filtration. Upon intake, the stream is typically filtered through one or more filtration units for removal of sediment, turbidity, and organic material. ...
- Softening. ...
- Chemical addition. ...
- Side-stream filtration. ...
- Post-treatment. ...
How does chlorine affect plants?
In particular, chlorine is important for plant photosynthesis as it is involved in the opening and closing of stomata (pores in leaves that enable plants to take in and release carbon dioxide, oxygen and other gases as required. It also helps ensure leaves are firm.
Why is chlorine used in water treatment plants?
Nearly every wastewater treatment facility uses chlorination to disinfect wastewater before the water is sent back out into the environment. The primary goal of chlorination is to disinfect the wastewater and remove any harmful pathogens that are present in the water.
Why is chlorine such as important part of the treatment?
Chlorine's use has seen it help to virtually eliminate waterborne diseases, such as cholera, typhoid and dysentery in developed countries. It also eliminates slime bacteria, molds and algae that commonly grow in water supply areas, on the walls of water mains and in storage tanks.
Why is chlorine added to water even though it is toxic?
Chlorine effectively kills a large variety of microbial waterborne pathogens, including those that can cause typhoid fever, dysentery, cholera and Legionnaires' disease. Chlorine is widely credited with virtually eliminating outbreaks of waterborne disease in the United States and other developed countries.
What are the benefits of chlorine in water?
The benefits of chlorination are:Proven reduction of most bacteria and viruses in water.Residual protection against recontamination.Ease-of-use and acceptability.Proven reduction of diarrheal disease incidence.Scalability and low cost.
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.
What is the purpose of adding chlorine to water?
The main objective of this chlorine addition is to disinfect the water and maintain chlorine residuals that will remain in the water as it travels through the distribution system.
Why is chlorination important in water treatment?
In order to combat waterborne diseases, different disinfection methods are used to inactivate pathogens. Along with other water treatment processes such as coagulation, sedimentation, and filtration, chlorination creates water that is safe for public consumption.
What is the combination of free chorine and hypochlorite?
At lower pH levels, the hypochlorous acid will dominate. The combination of hypochlorous acid and hypochlorite ions makes up what is called ‘free chorine.’. Free chlorine has a high oxidation potential and is a more effective disinfectant than other forms of chlorine, such as chloramines.
What is chlorine breakpoint?
Residual Chlorine, Breakpoint. Any type of chlorine that is added to water during the treatment process will result in the formation of hypochlorous acid (HOCl) and hypochlorite ions (OCl-), which are the main disinfecting compounds in chlorinated water. More detail is provided later on in this fact sheet.
How is calcium hypochlorite made?
Calcium hypochlorite (CaOCl) is made up of the calcium salts of hypochlorous acid. It is produced by dissolving chlorine gas (Cl 2) into a solution of calcium oxide (CaO) and sodium hydroxide (NaOH). Calcium hypochlorite is a white, corrosive solid that comes either in tablet form or as a granular powder. Calcium hypochlorite is very stable, and when packaged properly, large amounts can be purchased and stored until needed. The chemical is very corrosive however, and thus requires proper handling when being used to treat water. Calcium hypochlorite needs to be stored in a dry area and kept away from organic materials. It cannot be stored near wood, cloth or petrol because the combination of calcium hypochlorite and organic material can create enough heat for an explosion. It must also be kept away from moisture because the tablets/granular powder readily adsorb moisture and will form (toxic) chlorine gas as a result. Calcium hypochlorite has a very strong chlorine odour – something that should be kept in mind when placing them in storage.
What happens after chlorine demand is met?
After the breakpoint, any additional chlorine added will result in a free chlorine residual proportional to the amount of chlorine added.
How much calcium hypochlorite is needed for water treatment?
Compared to the 1-16 mg/L required with chlorine gas, only 0.5-5 mg/L of calcium hypochlorite is required. When calcium hypochlorite is added to water, hypochlorite and calcium ions are produced.
Chlorination
The STP treats the wastewater coming from agriculture, sewage and industrial plants. The treatment process has four stages (pretreatment, primary, secondary and tertiary treatment).
Chlorine Compounds as Disinfectant
We can add chlorine into the tertiary system via chemical feed inlets. Three standard formulations of chlorine are available for chlorination:
What is chlorine dioxide?
It is a chemical compound in a gaseous form possessing antimicrobial properties, which is used to disinfect water, surfaces, and a host of other areas.
Why use chlorine dioxide solution in water treatment?
The water reaching our taps is removed of the most harmful pathogens in the water treatment plants using chlorine dioxide. When reaching such plants the water contains pollutants such as parasites, chemicals, bacteria, or even human waste.
Chlorine dioxide to safeguard cooling water systems
Cooling water systems are used as heat sink in industries to remove heat generated through industrial processes. If the heat is not removed the equipment used in industries can get damaged. However, the capacity of such heat sinks can suffer due to the formation of biofilm inside.
What are the challenges of sodium hypochlorite?
Sodium hypochlorite poses three challenges your water treatment facility will need to overcome: UV rays, off-gassing, and oxidation. Poly Processing has established a set of best practices and containment solutions that overcome these challenges.
Is chlorine gas dangerous?
Chlorine gas is incredibly dangerous. If there’s a leak near residential or school zones, there could be a significant kill zone.
Is sodium hypochlorite an oxidizer?
Sodium hypochlorite is an incredibly aggressive oxidizing chemical. Using an antioxidant barrier can more than double the life of the chemical storage tank system and help ensure the safety of the tank. Traditional polyethylene tanks may fail when storing an oxidizer, but an XLPE tank with an inner-surface engineered polyethylene system helps protect your investment long term.
