Low-cost desulfurization wastewater pretreatment method

Abstract

The invention discloses a low-cost desulfurization wastewater pretreatment method which comprises the following steps of: introducing desulfurization wastewater into a primary reactor, adding carbideslag into the primary reactor, and conveying the reacted desulfurization wastewater in the primary reactor into a first-stage sedimentation tank; conveying the desulfurization wastewater subjected tofirst-stage sedimentation into an air floatation chamber, and introducing flue gas of a thermal power plant or high-concentration CO2 into the air floatation chamber to obtain Ca <2+>-removed desulfurization wastewater; introducing the desulfurization wastewater without Ca <2+> into a secondary reactor, and adding sodium carbonate into the secondary reactor; and conveying the reacted desulfurization wastewater in the secondary reactor into a secondary sedimentation tank. According to the method, lime is replaced by Ca(OH)2 in carbide slag; different from traditional lime treatment, the carbideslag contains a certain amount (8%-10%) of Mg / Al hydrotalcite; the Mg / Al hydrotalcite is a layered dicationic hydroxide compound; and electrons in the layered dicationic hydroxide compound can be subjected to ion exchange with the outside, so that the carbide slag has good adsorbability and is beneficial to improving the settling property of magnesium hydroxide.

Description

technical field [0001] The invention relates to the technical field of desulfurization wastewater treatment, in particular to a low-cost desulfurization wastewater pretreatment method. Background technique [0002] At present, more than 90% of the coal-fired power units that have been put into operation adopt the limestone-gypsum wet flue gas desulfurization process. Desulfurization performance and maintenance of Cl in the system - To balance, it is necessary to continuously discharge wastewater containing a large amount of heavy metal ions. Normally, the process routes for zero discharge of wastewater from coal-fired power plants mainly include pretreatment-concentration reduction-multi-effect evaporation technology, mechanical vapor recompression evaporation crystallization, flue evaporation, etc. High salt content can easily lead to scaling of equipment, Corrosion affects the stable operation of the system. Therefore, desulfurization wastewater must be pretreated before...

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Problems solved by technology

[0005] (2) Lime-Na 2 CO 3 / CO 2 Method: The traditional chemical precipitation method cannot meet the requirements of advanced wastewater treatment. Therefore, some researchers have proposed lime-Na 2 CO 3 pretreatment of desulfurization wastewater

[0008] The above-mentioned existing chemical pretreatment process mainly has the following problems: the process is long, the process is complicated, the effluent water quality fluctuates greatly and it is difficult to meet the discharge standard or the influent requirements of the subsequent process; the sedimentation rate of magnesium hydroxide formed after lime treatment is slow, resulting in The clarification and precipitation equipment occupies a large area; the amount of dosing is large, the energy consumption is high, and the direct operating cost is high; the investment cost is large, the operation and maintenance cost is high, and the homogenization treatment cost is high;

[0009] In view of the above-mentioned technical drawbacks in the traditional double-alkali pretreatment process, the present invention intends to solve the problem of slow sedimentation rate of lime treatment, improve the treatment efficiency of the overall process, and reduce operating costs

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