燃煤电厂脱硫废水的零排放处理技术

Zero liquid discharge(ZLD) technology of desulfurization wastewater in coal-fired power plant

采用化学沉淀—混凝—软化工艺对江苏某燃煤电厂湿法烟气脱硫废水进行物化法预处理,预处理后的废水再进行蒸发结晶,回收工业盐及冷凝水,最终实现了电厂脱硫废水的零排放。实验结果表明:在化学沉淀p H为9、混凝剂聚合硫酸铝铁(PAFS)加入量为2.5 m L/L、絮凝剂聚丙烯酰胺(PAM)加入量为2.0 m L/L的条件下,废水浊度可降至4.13 NTU,废水中的重金属、氟离子以及悬浮物被有效去除,预处理后废水的水质可达到GB8978—1996《污水综合排放标准》;蒸发结晶处理得到的工业盐和冷凝水分别符合GB/T 5462—2003《工业盐》的国家精制工业盐二级标准和GB 1576—2008《工业锅炉水质》的给水标准;脱硫废水的工业盐产率量为30 g/L。

The wastewater in wet flue gas desulfurization of a coal-fired power plant in Jiangsu province was pretreated by chemical precipitation-coagulation-softening process, and then industrial salt and condensate water were recovered from the wastewater by evaporation and crystallization, therefore zero liquid discharge （ZLD） of the desulfurization wastewater in coal-fired power plant was achieved. The experimental results indicate that： Under the conditions of chemical precipitation pH 9, coagulant PAFS dosage 2.5 mL/L and flocculant PAM dosage 2.0 mL/L, the turbidity of the wastewater can be decreased to 4.13 NTU, heavy metals, fluorine ion and SS in the wastewater are removed, and the quality of the pretreated wastewater meets the national discharge standard of GB 8978-1996; The quality of industrial salt meets the second grade national standard of GB/T 5462-2003, the quality of condensate water meets the national standard of GB 1576-2008; The yield of industrial salt from the desulfurization wastewater is 30 g/L.