基于膜吸收法处理实际高浓度蚀刻废液的研究

Treatment of actual high concentration etching solution based on membrane absorption method

为实现对印刷线路板生产领域高浓度蚀刻废液的高效处理,建立了“膜吸收+Na_(2)S破络+PAC混凝沉淀”工艺,考察其对实际高氨氮蚀刻废液的脱氨除铜效能,并优化了工艺条件。通过单因素实验探究了料液pH和流速、吸收液浓度和流速、膜组件级数与温度等因素对NH4+-N去除率、传质系数和过膜通量的影响,并确定了最佳运行参数:料液pH=10.5、流速3.6 cm/s,吸收液浓度2.0 mol/L、流速1.1 cm/s,膜组件级数为18级,温度为40℃。在该最佳运行条件下,蚀刻废液NH_(4)^(+)-N可由82000 mg/L降至100 mg/L左右,去除率保持在99.8%以上,膜传质系数为3.38×10^(-6)m/s,过膜通量为40.7 mg/(m^(2)·s)。同时对Na_(2)S破络及混凝沉淀工艺条件进行了优化,以n(S^(2-))/n(Cu^(2+))=1.4投加Na_(2)S对铜氨络合物进行破络,并投加150 mg/L PAC进行混凝沉淀,可将出水铜质量浓度控制在0.5 mg/L以下。重复实验结果表明,膜吸收法长期运行效能稳定,对印刷线路板高氨氮生产废水处理具有很好的适用性,是解决高浓度蚀刻废液污染问题的有效技术途径之一。

In order to realize the efficient treatment of high-concentration etching waste solution in printed circuit board production field,the process of membrane absorption+Na_(2)S breaking+PAC coagulation and precipitation was established to investigate the ammonia nitrogen and copper removal efficiency of the actual high-ammonia-nitrogen etching waste solution,and the process conditions were optimized.Single factor experiments were designed to ex⁃plore the influences of pH and flow rate of feed liquid,concentration and flow rate of absorption solution,stages of membrane modules and temperature on NH4+-N removal rate,mass transfer coefficient and membrane flux,and the optimal operating parameters were determined as follow:feed liquid pH=10.5,flow rate of feed liquid was 3.6 cm/s,absorption liquid concentration was 2.0 mol/L,flow rate of absorption liquid was 1.1 cm/s,film stages was 18,tem⁃perature was 40℃.Under the above conditions,NH4+-N could be reduced from 82000 mg/L to about 100 mg/L,the removal rate of NH4+-N remained more than 99.8%,the mass transfer coefficient was 3.38×10^(-6) m/s,and the trans⁃membrane flux was 40.7 mg/(m^(2)·s).At the same time,the process conditions of Na2S breaking and coagulation and precipitation were optimized.Na2S was added to the copper ammonia complex at the condition of n(S^(2-))/n(Cu^(2+))=1.4,and 150 mg/L PAC was added to the breaking solution for coagulation and precipitation,the copper concentra⁃tion in effluent could be controlled below 0.5 mg/L.The results of repeated experiments showed that the membrane absorption method had stable performance in long-term operation,and had good applicability to the treatment of high ammonia nitrogen production wastewater of printed circuit board.It was one of the effective technical ap⁃proaches to solve the pollution problem of high concentration etching waste solution.