High magnesium and low calcium desulfurization wastewater softening pretreatment device and method

Abstract

The invention relates to a high magnesium and low calcium desulfurization wastewater softening pretreatment device and a method. The high magnesium and low calcium desulfurization wastewater softening pretreatment device comprises a flocculation box, a precipitation box, a softening reaction box and a filter box that are communicated in order. The top of the flocculation box is connected to a first drug adding pipeline, the flocculation box is internally equipped with a first aeration apparatus, and the bottom of the flocculation box is connected to a first slagging pipeline. The bottom of the precipitation box is communicated with the first slagging pipeline. The top of the softening reaction box is connected to a second drug adding pipeline and a seed crystal reuse pipeline, and the softening reaction box is internally equipped with a stirrer. The filter box is internally equipped with a micro-filtration membrane component and a second aeration apparatus, and the bottom of the filter box is connected to a second slagging pipeline. The micro-filtration membrane component is connected to a water outlet pipeline, which is provided with a water outlet pump. The device and the method provided by the invention can achieve selective separation of Ca<2+> in wastewater, compared with the conventional caustic soda / slaked lime-soda ash process, the device and the method provided by the invention reduce the sediment production and lower the softener delivery amount and cost.

Description

technical field [0001] The invention relates to a device and method for softening and pretreating desulfurization wastewater with high magnesium and low calcium content. The device can reduce the amount of sediment generated in the softening process, reduce the dosage and cost of softener, and belongs to the environmental protection technology field. Background technique [0002] SO 2 As a kind of thermal power waste gas that pollutes the environment seriously, its emission has been increasingly restricted by the state. In order to achieve clean emission of flue gas, most thermal power plants in China have added flue gas desulfurization systems. According to statistics, among many flue gas desulfurization technologies, the limestone-gypsum wet desulfurization process accounts for as much as 90%. Harsh desulfurization wastewater. As the country pays more and more attention to water pollution, the wastewater is an important source of water pollution, and its discharge is s...

AI Technical Summary

Problems solved by technology

However, the oxalic acid used in this study is an organic acid. In order to maintain a certain pH of the wastewater, additional ammonia water must be added to it for neutralization. If it is directly applied to the desulfurization wastewater, it will increase the softening cost and process flow, and will increase the NH in the wastewater. 4 + Concentration, new pollutants need further treatment

In addition, the water quality of the rare earth wastewater targeted by this study is quite different from that of desulfurization wastewater. For example, its suspended solids content is only below 4 mg / L, while the suspended solids content of desulfurized wastewater can reach thousands to tens of thousands of mg / L; its magnesium and calcium ions The concentration ratio is only 5:1, and the desulfurization wastewater Mg with high magnesium and low calcium content 2+ Concentrations up to Ca 2+ 15-20 times of that; its solution is neutral, while desulfurization wastewater is weakly acidic, so it is difficult to be directly applied to desulfurization wastewater softening

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