Method and processing device thereof for removing hardness in water by combined multiple steps

A treatment device and hardness technology, applied in water/sewage treatment, water/sewage multi-stage treatment, water/sewage treatment equipment and other directions, can solve the problems of high resin price, regeneration of waste liquid, large amount of mud production, and restricted development, etc. Achieve significant environmental and social effects, stable effluent turbidity, and reduced sludge volume

Pending Publication Date: 2019-02-19
TIANJIN UNIV
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Problems solved by technology

The ion exchange method is affected by the exchange capacity of the resin, and has strict requirements on the salt content of the influent, and the price of the resin is relatively high, and the regeneration waste liquid needs to be further processed; the electrochemical method consumes a lot of power and is suitable for high salt content. A large amount of drinking water treatment; although nanofiltration / reverse osmosis can efficiently remove hardness in water, its high energy consumption limits the application and promotion of the technology, and the chemical precipitation-microfiltration / ultrafiltration technology has serious membrane pollution and is difficult to realize engineering defects.
[0004] The lime-soda precipitation softening method has simple process and high sedimentation rate, and is suitable for softening treatment with different requirements, but its large sludge production and long static settling time lead to large structures and high sludge disposal costs
Novel chemical precipitation methods such as microbially catalyzed CaCO based on urea hydrolysis 3 Precipitation method, using CO 2 dissolve in water to produce CO 3 2- , making it with Mg 2+ , Ca 2+ Form precipitation, etc. Although it can remove the hardness in water well, it is difficult to apply in engineering, which limits its development.

Method used

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  • Method and processing device thereof for removing hardness in water by combined multiple steps

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Experimental program
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Effect test

Embodiment 1

[0029] The flow rate of the device is 0.63m 3 / h, the stirring intensity G value of the granulation stirring tank is 556s -1 , the residence time of the membrane separation tank is 35min, the calcium ion concentration of the raw water is 36mg / L, and the total hardness (calculated as CaCO 3 Count) is 140mg / L. When the experiment was started, 1000mg / L of calcium carbonate seeds prepared in advance were added to the granulation mixing tank. In the experiment, the dosage of sodium carbonate was 1000mg / L, and the dosage of ferric chloride (based on Fe 3+ ) was 3.5mg / L, stirred for 20min, and statically settled for 15min. The average concentration of calcium ions in the effluent was 0.91mg / L, and the removal rate was 97.5%; the average value of total hardness was 22.03mg / L, and the removal rate was 84.3%.

Embodiment 2

[0031] The flow rate of the device is 0.84m 3 / h, the stirring intensity G value of the granulation stirring tank is 556s -1 , the residence time of the membrane separation tank is 30min, the calcium ion concentration of the raw water is 32mg / L, and the hardness (calculated as CaCO 3 Count) is 130mg / L. When the experiment was started, 500 mg / L of calcium carbonate seeds prepared in advance were added to the granulation mixing tank. In the experiment, the dosage of sodium carbonate was 1000 mg / L, and the dosage of ferric chloride (based on Fe 3+ ) was 3.5mg / L, stirred for 15min, and statically settled for 10min. The average concentration of calcium ions in the effluent was 1.14mg / L, and the removal rate was 96.5%; the average value of total hardness was 23.07mg / L, and the removal rate was 82.3%. After the experiment, the average value of crystal particles increased from 32.42 μm to 142.00 μm.

Embodiment 3

[0033] The flow rate of the device is 0.63m 3 / h, the stirring intensity G value of the granulation stirring tank is 416s -1 , the residence time of the membrane separation tank is 35min, the calcium ion concentration of the raw water is 40mg / L, and the hardness (calculated as CaCO 3 Count) is 140mg / L. When the experiment was started, 400mg / L of calcium carbonate seeds prepared in advance were added to the granulation mixing tank. In the experiment, the dosage of sodium carbonate was 1000mg / L, and the dosage of ferric chloride (based on Fe 3+) was 3.5mg / L, stirred for 20min, and statically settled for 15min. The average concentration of calcium ions in the effluent was 1.16mg / L, and the removal rate was 97.1%; the average value of total hardness was 21.20mg / L, and the removal rate was 84.9%.

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Abstract

The invention relates to a method and a processing device for removing hardness in water by combined multiple steps. The method includes the steps of pelleting, precipitating and coagulating/membraneseparating: calcium carbonate seed crystals and sodium carbonate precipitant are input into a pelleting stirring pond to react with raw water completely, newly generated calcium carbonate is enabled to precipitate on surfaces of the continuously input calcium carbonate seed crystals, and formed large-size dense crystal particles are enabled to quickly precipitate at the bottom of the pelleting stirring pond, and accordingly a large amount of calcium and magnesium ions are removed; non-precipitated small-size crystal particles enter a membrane separation pond along with supernate and react witha hydrolysis product of ferric salt to form large-size flocculent particles, the calcium and magnesium ions are furtherly removed through hollow fiber ultrafiltration membrane separation, and hardness of outlet water is reduced largely. The method and the processing device for removing hardness in the water by the combined multiple steps have the advantages that formed crystal particles are largein size and good in settling property, the defects of long static settling time, large quantity of produced mud and the like of a lime-soda precipitating and softening method are overcome, a ferric chloride coagulant is input into the membrane separation pond to slow down membrane pollution, hardness removing efficiency is increased, and remarkable environmental and social effects are realized.

Description

technical field [0001] The invention relates to a water treatment technology, specifically to remove calcium ions and magnesium ions from water, and provides a multi-step combined method for removing hardness in water and a treatment device thereof. Background technique [0002] Hardness is an important water quality indicator, usually characterized by the content of calcium ions and magnesium ions in water. In real life, drinking hard water can cause gastrointestinal disorders, and even induce cardiovascular, nervous, and urinary system lesions. In industrial production, too high hardness may reduce the quality of the product, or form scales to block pipes, etc., affecting normal production or causing explosions. Therefore, it is of great significance to remove calcium ions and magnesium ions in water. [0003] Hardness ions in water are usually removed by chemical precipitation, ion exchange, membrane separation and electrochemical methods. The ion exchange method is af...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F101/10
CPCC02F9/00C02F2201/002C02F2101/10C02F2001/5218C02F1/5245C02F1/5236C02F1/444
Inventor 张光辉樊伟郭美彤国中馨顾平侯立安董丽华
Owner TIANJIN UNIV
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