中国90%以上燃煤电厂使用石灰石-石膏湿法脱硫工艺进行烟气脱硫,需从脱硫系统定期外排部分废水以保证脱硫效果.作为燃煤电厂末端废水,脱硫废水具有水量大、水质差、成分复杂等特点,直接排放对环境具有极大危害;脱硫废水零排放工艺在实现水资源最大化利用、副产物分级回收的同时,还可以达到水中杂质和硬度离子的最佳去除效果,因此对脱硫废水进行零排放处理十分必要;预处理工艺作为脱硫废水零排放工艺的基础,其处理效果的好坏对后续工艺具有较大影响.在清洁生产和污染减排的背景下,从脱硫废水零排放预处理工艺理论展开叙述,对比国内外零排放工艺,并对山西某燃煤电厂进行调研后发现已有预处理工艺普遍存在药剂投加量大、处理成本高等问题,故需寻找一种经济可行的预处理原材料,替代现行双碱法工艺中的氧化钙或者优化其加入量,实现燃煤电厂脱硫废水低成本资源化利用.
More than 90%of coal-fired power plants use limestone-gypsum wet desulfurization process for flue gas desulfur-ization,and need to discharge part of the wastewater from the flue gas desulfurization system periodically to ensure the de-sulfurization effect.As the end wastewater of coal-fired power plants,desulfurization wastewater has the characteristics of large volume,poor quality and complex composition,and its direct discharge is extremely harmful to the environment.While the zero liquid discharge process of desulfurization wastewater can achieve the best removal effect of impurities and hard-ness ions in water and maximize the utilization of water resources and recycling of by-products in a graded manner,so it is necessary to treat desulfurization wastewater with zero liquid discharge.The pretreatment process is the basis of the zero liq-uid discharge desulfurization wastewater process,and its treatment effect has a great influence on the subsequent process.In the background of clean production and pollution reduction,this paper was started from the theory of zero liquid discharge pretreatment process for desulfurization wastewater,after comparing domestic and foreign zero liquid discharge processes and conducting research on a coal-fired power plant in Shanxi,it was found that the existing pretreatment process generally had problems such as high dosage of chemicals and high cost.Therefore,it was necessary to find an economically feasible pretreatment raw material to replace the calcium oxide in the current dual alkali process or to optimize its addition to achieve low-cost resource utilization.