The lime soda process involves the chemical conversion of all the soluble hardness. Perhaps just an excel spreadsheet program to share and perhaps build upon. Know the differences among the three lime soda softening process alternatives described be able to recommend the choice of the three lime soda softening process alternatives to use for a water sample with a known value of magnesium hardness and knowledge of whether the water is from a groundwater source or from a surface water source. Headquartered in northbrook, illinois, culligan has over 800 companyowned and franchise dealers in north america. Addition of lime cao and soda na2co3 to the hard water precipitates calcium as the carbonate, and magnesium as its hydroxide. Hello friends, engineers funda is created to spread the knowledge of life science by. Ion exchange softening is typically used for groundwater softening and for home water softeners, while lime soda water softening is the usual method of choice for a surface water source. The lime softening process offers many benefits, including the reduction of. Softening by lime and limesoda ash is generally less expensive then by caustic soda. Once water hardness is known, you have two options. Limesoda ash softening process 10 when lime and soda ash are added, hardnesscausing minerals form nearly insoluble precipitates.
The process is also effective at removing a variety of microorganisms and dissolved organic matter by flocculation. Advantages and disadvantages of lime softening biotech. Reactor reactions and stoichiometry of lime softening 2 lime in the name of lime softening is based on it being the main added chemical in this process. Most modern browsers have builtin pdf readers if you have problems opening this file in your browser, check your. The coagulant may be supplemented by an anionic or a nonionic flocculant. A watersoftening process in which water is treated with hydrated lime sometimes in combination with soda ash, which reacts with dissolved calcium and magnesium compounds to form precipitates that can be removed as sludge. Cold lime soda process free download as powerpoint presentation. The most common gravityclarification process is cold lime softening. When hydrated lime, caoh2, is added to the water being treated, the following reactions occur mghco32 magnesi um bicarbon ate.
Soft water also extends the lifetime of plumbing by reducing or eliminating scale buildup in pipes and fittings. Pdf process optimization for lime soda water softening. This process is now obsolete but was very useful for the treatment of. Lime softening water treatment lime softening process. The chemicals used are safer for the operator to handle and operation is much easier. Despite all the benefits of lime softening there are also some adverse effects. Addition of lime cao and soda na2co3 to the hard water.
Lime is used to remove chemicals that cause carbonate hardness. The raw water is passed into a tank with a static continuous flow, at the same time a calculated amount of chemical mixture of lime and soda ash are also. As a result precipitation becomes almost complete very quickly. Calculations are presented for daily chemical requirements and solids production rates. Lime soda water softening method is one of the most traditional chemical methods in water purification process used for reducing the hardness of well water. Cold lime softening precipitation softening accomplished at ambient temperatures is referred to as cold lime softening. Chemical precipitation is one of the more common methods used to soften water. Lime softening lime softening is an operation which has been used for the past 150 years to remove hardness and soften the water.
Cold lime soda process sodium carbonate calcium scribd. The precipitated caco 3 and mgoh 2 are filtered off. Either hydrated lime caoh2 or quicklime cao may be used in the softening process. Fundamentals of water softening process water water. By this process soluble magnesium and calcium salts are removed as calcium carbonate and magnesium hydroxide precipitated. The acceptable water hardness range is between 60120 mgl as caco 3. The resulting soft water requires less soap for the same cleaning effort, as soap is not wasted bonding with calcium ions. The two most widely used methods for softening water reducing hardness to an acceptable level are lime soda water softening and ion exchange softening. Lime cannot remove the calcium permanent hardness which. Chemistry water with high magnesium hardness requires excess lime treatment to increase of ph to 11. The process decreases the acidity that is associated with the minerals in the hard water. In lime soda process, in addition to washing soda lime is added to remove temporary hardness. Hardness of water, water softening, base exchange method.
Zeolite resin exchanges sodium for calcium and magnesium. The deep bed filter is implemented in the oil removal step orf, prior to the lime softening process, and the softening step after filter, post lime softening. The strong acid ion exchange resin in sodium form is used for. Lime softening study guide wisconsin department of. Limesoda water softening process limitation of soda lime. Lime softening, also known as clarks process, is a type of water treatment used for water softening which uses the addition of limewater calcium hydroxide to remove hardness calcium and magnesium ions by precipitation. There is also information about three lime soda water softening process alternatives two stage excess lime water softening, split treatment, and selective calcium removal, along with calculation of the dosages needed for lime, soda ash, and carbon dioxide. Would anyone be able to recommend a source for hot lime softener modeling software to help calculate lime, soda ash and mgo feed rates for treatment of a given water.
Water softening is an important process, because it can extend the lifespan of household appliances and pipelines, as well as improve function and lifespan of solar heating systems, air conditioning units and many other waterbased. Addition of lime cao and soda na 2 co 3 to the hard water precipitates calcium as the carbonate, and magnesium as its hydroxide. Cold lime softening sewage treatment reverse osmosis. In this system calcium hydroxide and soda ash are used as reagents.
Solids contract unit differentiate between gravimetric and volumetric dry feeders. Introduction lime soda process is a method of softening hard water. Cold lime softening process is used to reduce raw water hardness, alkalinity, silica, and other constituents. The chemical mixing process is same as the cold lime soda process, but steam is applied in mixture tank. In this process, hydrated lime is added to the water to raise its ph level and precipitate the ions that cause hardness. Lime reacts with temporary hardness, co 2, acids, bicarbonates and alums.
At the site, the oil removal filter influent is between 100 ppm and 300 ppm with an effluent less the 3 ppm oil and solids. The water chemist distinguishes between cold process lime softening, usually carried out in the range of 40 to 9o0f 4 to 320c, and hot process, at 215 to 23o0f 102 to 11o0c. This helps prepare water for direct use as cooling tower makeup or as a firststage treatment followed by ion exchange for. Cold limesoda water softening experiences with spaulding precipitators.
A water softener, also called an ion exchange unit, will effectively accomplish the latter option. Soda lime is a process used in water treatment to remove hardness from water. With cold water typical for groundwater time 5 to 10. Article views are the countercompliant sum of full text article downloads since november 2008 both pdf and html across all institutions and individuals. Limesoda water softening process and its advantages notes. Fundamentals of water softening culligan international has been in the water treatment business since 1936. Water resources engineering civil engineering engc 6305. We supply lime softeners to the oil sands and we are an exclusive supplier of hot lime softeners for the sagd process. A lime dosage range of 30180% of the stoichiometric amount. For calcium removal, the required lime and soda ash dosages are calculated by sto chiometry. Softening is a process where calcium and magnesium ions are exchanged for sodium ions. This process is more effective than cold lime soda process. Water softening is a process through which calcium, magnesium and certain other metal cations in hard water are removed. Cold lime soda process in the cold lime soda process the reactions take place at normal temperature.
Limesoda water softening process and its advantages notes pdf ppt. Ecodyne offers a wide variety of custom designed water treatment equipment, and therefore can be the sole source for all your water treatment needs. Limesoda ash softening is assumed to be capable of reducing calcium and magnesium to empirically determined practical limits of 0. Currently i am working on hot lime softening project. Limesoda water softening process limitation of soda. Chemicals normally used are lime calcium hydroxide, caoh 2 and soda ash sodium carbonate, na 2co 3. Lime softening is a very viable way of water softening because when it is added to the hard water, it dissolves all the minerals in the hard water.
Lime softening is a water treatment process that uses calcium hydroxide, or limewater, to soften water by removing calcium and magnesium ions. What is the hot lime soda process of water treatment. Soda ash is used to remove chemicals that cause noncarbonate. The ion exchange process is more costeffective when treating ground waters, as they are typically a non. A water softening experiment was conducted in replicate to observe the changes in parameters such as total hardness, calcium hardness, magnesium hardness, alkalinity and ph with varying dosages of lime. Sketch a drawing of a typical lime softening facility, identifying processes and points of chemical addition in the appropriate order for each of the following. Lime soda softening process can be carried out at ambient temperatures known as cold. Lime soda process is one of the water softener systems. This article first covers how gravity clarifiers work, some of the chemicals used in clarification, proper chemical feeding procedures, and clarifier equipment designs. This process is now obsolete but was very useful for the treatment of large volumes of hard water. In lime sodaash softening plants, the softening process may be carried out by a. It also explains how cold lime softening works, and provides guidance on maintaining system reliability.
Culligan offers a wide range of water treatment services for consumers and businesses. Lime softening is best suited to groundwater sources, which have relatively stable water quality. Effectiveness 80100 mgl as caco3 is usually considered acceptable result of limesoda ash softening, as long as mg is water hardness range is between 60120 mgl as caco 3. However, caustic softening produces less sludge and unlike lime does not deteriorate during storage. Soda lime is a process used in water treatment to remove hardness. You can live with the hardness level, recognizing that levels below 7. The following chemical reactions show the exchange process, where x represents zeolite, the exchange material. Compared with limesoda ash softening, ionexchange has certain advantages. Caustic soda softening is typically used when the treated water has inadequate carbonate hardness to react with lime. The hot lime soda process water softener systems are exclusively used for boiler purpose. Water softening is the removal of calcium, magnesium, and certain other metal cations in hard water. This article will discuss lime softening through a new perspective, instead of going through the detailed chemical equations. Hardness is the term often used to characterize a water that.
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