Composite coagulant for flue gas desulfurization waste liquid treatment and its preparation method and application

Abstract

The invention provides a composite coagulant for treating flue gas desulfurization wastewater as well as a preparation method and application of the composite coagulant. The composite coagulant is prepared from poly aluminum chloride and cationic polyacrylamide, wherein the mass of the cationic polyacrylamide is 3-6% of the mass of the poly aluminum chloride. According to the invention, the poly aluminum chloride forms a series of hydrolytic hydroxyl ions with positive charges in water and has relatively strong ability of adsorbing charge neutrality and compressing an electric double layer and is conductive to promotion of elimination of colloid stability in water; the cationic polyacrylamide has a ring and chain structure and also has a hydrophilic group to realize very strong ability of adsorption bridging; the advantages of net fishing and bridging can be fully developed by use of a relatively small dosage, based on the elimination of colloid stability, and the removal rate of suspended particulate matters in the flue gas desulfurization wastewater is increased through sufficient adsorption of the suspended particulate matters. The results of the embodiments indicate that the composite coagulant provided by the invention can realize up to 95-99% of removal rate of the suspended particulate matters in the flue gas desulfurization wastewater.

Description

technical field [0001] The invention belongs to the technical field of water treatment, and in particular relates to a composite coagulant for flue gas desulfurization waste liquid treatment and a preparation method and application thereof. Background technique [0002] Nowadays, sulfur dioxide and acid rain pollution have become major environmental problems. The petrochemical industry will produce a large amount of sulfur-containing flue gas during the deep processing of sulfur-containing crude oil. As an important industry that emits sulfur dioxide and causes acid rain pollution, if no measures are taken, it will not only cause serious harm to the atmospheric environment, but also restrict the development of the power system. Catalytic cracking sulfur-containing flue gas is mainly treated by wet method. Among them, in the wet desulfurization, the sodium-alkali method is more commonly used, resulting in a large amount of fine suspended solids (2-5 μm catalyst dust accounts...

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Problems solved by technology

[0003] However, the suspended solids contained in flue gas desulfurization waste liquid have small particle size (micron scale), light specific gravity, and slow settling velocity. The conventional coagulation treatment process has certain limitations.

According to field engineering experience, for flue gas desulfurization waste liquid with a suspended solid concentration of 1200-2000 mg / L, the removal rate of TSS by conventional inorganic coagulants such as ferric sulfate and aluminum chloride is only about 85%, and ferric chloride can Reached about 90%, but the dosage of chemicals is large, and the effluent TSS still has the problem that it cannot meet the drainage requirements of the industry