Desulfurization wastewater treatment method

Abstract

The invention provides a desulfurization wastewater treatment method. The method comprises the following steps: primary softening treatment: adding an alkaline agent, polyaluminum chloride and a sludge extracellular polymeric substance containing carboxyl functional groups into the desulfurization wastewater, reacting and precipitating SO4 < 2-> in the wastewater, and further separating to obtain supernate to realize primary softening treatment of the desulfurization wastewater; wherein the alkaline agent comprises calcium hydroxide and / or calcium oxide; and second-stage softening treatment: adding NaOH and Na2CO3 into the supernatant obtained by the first-stage softening treatment, reacting and precipitating Ca < 2 + > and Mg < 2 + > in the supernatant obtained by the first-stage softening treatment, and further separating to obtain the supernatant, thereby realizing the second-stage softening treatment of the desulfurization wastewater. According to the method, SO4 < 2->, heavy metal ions and Mg < 2 + > can be effectively removed under the condition that less Ca (OH) 2, NaOH and Na2CO3 are used.

Description

technical field [0001] The invention belongs to the technical field of environmental protection chemical industry, in particular to a desulfurization wastewater treatment method suitable for the zero discharge process of desulfurization wastewater. Background technique [0002] With the focus on environmental protection issues in the thermal power industry and the rising price of industrial water, desulfurization wastewater is the final link of water treatment in coal-fired power plants. Realizing its zero discharge is of great importance for power plants to increase production, reduce consumption and reduce emissions. meaning. The main components of desulfurization wastewater are gypsum particles, silica and hydroxides of iron and aluminum, etc., and also contain a large amount of SO 4 2- , Ca 2+ , Mg 2+ , Cl - And various heavy metal ions, the composition is complex and changeable and difficult to handle. At present, the zero discharge of desulfurization wastewater u...

AI Technical Summary

Problems solved by technology

Mg removal by adding more milk of lime to control system pH 2+ , SO in water 4 2- in Mg 2+ The treatment requirements have already been met before reaching the standard. A large amount of lime milk in the system is easy to sink to the bottom of the pond due to the slow dissolution rate, the utilization rate is low, and the chemical consumption is huge (up to 30g lime / m 3 waste water), the water quality of the system effluent is unstable (Mg 2+ Fluctuating at 2000-4000mg / L), the sludge output is large

[0007] (2) Excess milk of lime makes Ca in water after primary softening treatment 2+ The sharp increase in the concentration leads to a great increase in the dosage of soda in the secondary softening treatment and the operation and maintenance cost of the system, resulting in a great waste of chemicals

[0009] On the one hand, iron salts will form water-soluble substances with impurities in the water, making the effluent colored;

[0010] On the other hand, due to the strong acidity of iron salt, it is corrosive to equipment;

[0011] Furthermore, polyacrylamide is a synthetic organic polymer coagulant, and acrylamide will remain in the water after treatment, which has a certain risk of damage to the nervous system of the operator.

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