火力发电厂脱硫废水硬度的测定

Determination of Thermal Power Plant Desulfurization Wastewater Hardness

火力发电厂脱硫废水主要来自石膏脱水和清洗系统的清洗废水等,然而脱硫废水水量排放差别较大,间断排放且不稳定,水质中钙、镁、氟等离子处于过饱和状态,易出现严重的结垢现象,同时水中还含有大量重金属,给水质硬度的测定增加了难度.通过实验对比了2种水质硬度测定方法:1)采用乙二胺四乙酸(ethylened-iaminetetraacetic acid,EDTA)二钠滴定法直接测定水硬度;2)采用火焰原子吸收分光光度法(atomic absorption spectrophotometry,AAS)先测定钙镁浓度再计算水硬度.实验结果表明,2种方法的硬度测定结果无显著性差异.AAS法因其高效、绿色环保等特点,在批量化分析测定中更有优势,可作为火力发电厂脱硫废水硬度测定的方法.

The desulphurization wastewater of thermal power plants mainly comes from gypsum dewatering and cleaning wastewater of the cleaning system,etc.However,the discharge volume of desulphurization wastewater is quite different,discontinuous and unstable.Calcium,magnesium and fluorine plasma in water are supersaturated,which is prone to serious scaling,and the water also contains a lot of heavy metal ions.Therefore,it is more difficult to determine the water hardness.Two kinds of water hardness determination methods,namely,direct determination of water hardness by ethylenediaminetetraacetic acid(EDTA)titration,and determination of calcium and magnesium concentration before indirect calculation of water hardness by flame atomic absorption spectrophotometry(AAS)were compared through experiments.The results show that there was no significant difference in the hardness test results of the two methods.The AAS is more advantageous in quantitative analysis because of its characteristics such as high efficiency and environmental protection;it can be used as a method to determine the hardness of desulphurization wastewater in thermal power plants.