Method for removing nitrosamine precursors in water by regulating pH and enhancing ion exchange

A nitrosamine precursor, ion exchange technology, applied in ion exchange water/sewage treatment, chemical instruments and methods, water/sewage multi-stage treatment, etc. Insufficient and other problems, to achieve the effect of efficient removal, simple operation and low operating cost

Active Publication Date: 2014-11-26
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the use of strong oxidants can be interfered by the presence of other abundant organics in the water, resulting in an insufficient dose to react with nitrosamine precursors
Moreover, the use of high doses of oxidants will also lead to a substantial increase in disinfection by-products such as trihalomethanes and haloacetic acids, and lead to increased water purification costs

Method used

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  • Method for removing nitrosamine precursors in water by regulating pH and enhancing ion exchange
  • Method for removing nitrosamine precursors in water by regulating pH and enhancing ion exchange
  • Method for removing nitrosamine precursors in water by regulating pH and enhancing ion exchange

Examples

Experimental program
Comparison scheme
Effect test

Embodiment approach 1

[0041] Embodiment 1, pH adjustment and ion exchange device for controlling the generation of nitrosamines in waterworks

[0042] For waterworks using conventional processes, when there is a high concentration of nitrosamine precursors in the source water, due to the low removal effect of conventional processes, it is recommended to add an ion exchange unit between the filter effluent and the clean water tank, and in the coagulation process Steps add acid to lower the pH. The specific method is to add acid to adjust the pH value to 6.5-7.0 in the coagulation process; according to the water volume and other requirements, select a suitable model of standard cation exchange tank, connect the effluent from the filter to the cation exchange tank, and after ion exchange The effluent is reinjected into the clear water tank. Chlorination point should be set after ion exchange.

Embodiment approach 2

[0043] Embodiment 2, a cation exchange module used in household water purifiers to control the generation of nitrosamines

[0044] An ion exchange column is added to the conventional multi-stage household water purifier structure. The ion exchange column should be set after the security filter, ultrafiltration membrane, and activated carbon filter column to reduce the impact of turbidity, microorganisms, and residual chlorine in the water on the ion exchange resin. If the water purifier also has reverse osmosis and UV units, the ion exchange unit should be in front of it.

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Abstract

The invention relates to a method for removing nitrosamine precursors in water by regulating pH and enhancing ion exchange, belonging to the technical field of water treatment. The invention is characterized in that the method uses a sodium-type strongly-acidic cation exchange resin to remove the nitrosamine precursors; and if the hydrogen-type strongly-acidic cation exchange resin should be converted into sodium type before use. Water to be treated is filled into an ion-exchange column, wherein the filtering velocity is 20-60 m/hour, the resin filling height is more than 1M, and the empty bed contact time is not less than 2 minutes. An acidic reagent is added into the influent water to lower the pH value to less than 7, thereby further enhancing the removal effect of the nitrosamine precursors. The hardness of the influent water and the hardness of the effluent water of the ion-exchange column are tested periodically; and the resin should be regenerated when the hardness of the effluent water greatly increases and is even identical to that of the influent water. A sodium chloride saturated solution is used in the regeneration process. The method for removing nitrosamine precursors in water by combination of pH regulation and ion exchange can effectively control the generation of nitrosamine in the water; the equipment is simple to operate and convenient for water plants to use; and the method is also applicable to domestic water purifiers.

Description

technical field [0001] The invention relates to a water treatment method for treating nitrosamine precursors in water, belonging to the field of water supply and drainage treatment. Background technique [0002] Nitrosamines are a class of strong carcinogens. At present, research has confirmed that nine kinds of nitrosamines, such as dimethylnitrosamine (NDMA), diethylnitrosamine (NDEA), and dipropylnitrosamine (NDPA), can be produced in the process of water supply and drainage disinfection treatment. . In water treatment, nitrosamine substances mainly come from precursors containing dialkylamine structures in water. For example, dimethylamine is the direct precursor of dimethylnitrosamine. In addition, some medicines, water purification agents, Sewage plant effluent and domestic sewage can also contribute high levels of nitrosamine precursors. Chloramine disinfectants commonly used in water treatment can react with nitrosamine precursors to generate higher concentrations...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F9/08C02F1/42
Inventor 陈超张晓健李士翔汪隽
Owner TSINGHUA UNIV
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