Two types of existing zero-discharge technologies(pretreatment-conventional evaporation crystallization and pretreatment-membrane concentration-conventional evaporation crystallization) applied domestically were examined in the applications of wastewater of desulfurization processes. Combining with the characteristics of the actual waste water and flow patterns of a coal-fired power plant

the technical and economic pros and cons of these two processes were analyzed to explore a suitable zero-discharge technology for the desulfurization wastewater. The results showed that both of these two technologies have disadvantages

like high investment and operation cost

crystallization of mixed salts

and others. Improvement ideas and suggestions on the technical development of zero-discharge of desulfurization wastewater were provided. It suggests the suspended solids and calcium magnesium ions should be removed in the pretreatment process as the very first step

and then the sodium chlorides and sodium sulfates should be separated via nanofiltration-low temperature crystallization. The sodium chloride solution should be further concentrated through reverse osmosis combined with electrodialysis and finally the crystalline salts be recycled by crystallization and drying processes.