胶印含铬废水化学处理工艺条件应用研究

Utilization Study on the Technological Conditions of the Chemical Treatment of Wastewater of Cr from Offset Printing

实验研究了胶印含铬废水化学处理的方法及工艺条件。经化学法处理 ,Cr( )和总 Cr的浓度均能达到国家工业污水排放标准 ;研究结果表明 ,废水中 Cr( )还原成 Cr( )的反应 ,还原剂 Na HSO3 投加量应是 Cr( )重量的 7倍以上 ;Cr(OH) 3 的沉淀反应的适宜 p H范围在 7.5～ 8.5 ,以 p H 8.0时为最佳 ;Cr(OH) 3 的沉淀反应的搅拌时间应在 2 0 min以上为宜 ;沉淀反应的烘干沉渣量为废水总 Cr量的 11倍。

The chemical treatment method and its technological conditions have been studied in this paper. The content of Cr(Ⅵ)and total Cr both can achieve the national effluent standard of the industrial wastewater(GB8978 1996) through a chemical treatment. The experimental results show that the dosing amount of reduction agent NaHSO 3should be greater than 7 times of Cr(Ⅵ) weight in the reaction of Cr(Ⅵ) reduction into Cr(Ⅲ). The appropriate pH range for the sedimentation reaction of Cr(OH) 3 is 7.5~8.5, the optimal pH is about 8.0. The stirring time of 20 minute or longer would be proper in the sedimental reaction of Cr(OH) 3. The weight of dried sediment formed by sedimental reaction is 11 times of total Cr in the wastewater. The results of experimental research can provide the theoretical base for the technological design of wastewater treatment of Cr.