高炉水淬渣对电镀废水中重金属和COD吸附的响应面优化

Application of response surface methodology to optimize adsorption conditions for heavy metals and COD in electroplating waste water by water-quenched blast furnace slag

为了考察高炉水淬渣处理实际电镀废水中重金属离子和COD的可行性,分别研究了吸附剂投加量、p H、吸附时间以及温度等单因素对Cu^(2+)、Zn^(2+)或COD去除率的影响。在单因素实验的基础上,应用Box-Behnken中心组合方法进行三因素三水平试验,建立二次多项数学模型,并验证该模型的有效性。采用响应曲面法探讨吸附剂投加量、p H、吸附时间3个因子的交互作用及其最佳水平。结果表明:在吸附剂投加量为1.4g、p H为8、吸附时间为120min的最优化条件下,电镀废水中Cu^(2+)、Zn^(2+)和COD去除率达到最大,分别为99.35%、98.46%和53.63%。经对最优条件进行验证,预测值与验证实验平均值接近。吸附后废水中的Cu^(2+)和Zn^(2+)低于GB 21900—2008电镀废水新建企业污染物排放限值要求,而COD没有满足排放要求,所以仅应用高炉水淬渣吸附技术还不足以去除电镀废水中所有有害物质,因此可利用此技术作为辅助工艺,联合其他技术共同去除电镀废水中的重金属离子和有机物,使出水水质达到国家排放标准。

In order to study the feasibility of the treatment of heavy metal ions and COD in electroplating wastewater by water-quenched blast furnace slag（WBFS）,the effect of factors,such as adsorbent dosage,pH,contact time and temperature on the adsorption of Cu^2＋、Zn^2＋ and COD were investigated. On the basis of single factor experiments,a three-factor,three-level Box-Behnken central composite design（CCD） was utilized. Two multinomial mathematical models were established by response surface methodology,and the effectiveness of the model was verified. Response surface analysis was used to discuss the interaction of the three factors and determine the optimum level of the main effects. The results showed that the optimal adsorption conditions were adsorbent dosage 1.4g,pH 8,contact time 120 min,and under these conditions,the removal of Cu^2＋、Zn^2＋ and COD was 99.35%、98.46% and 53.63%,respectively. The experimental data and model predictions agreed well. The concentrations of Cu^2＋ and Zn^2＋ in the effluent were lower than the standard limitation of newly-built enterprises in electroplating wastewater（GB 21900—2008）,and COD could not satisfied with the emission requirement. So the application of blast furnace slag adsorption technology was not enough to remove all harmful substances in electroplating wastewater. Therefore,it could be used as an assistant process,combined with other technologies to remove heavy metal ions and organic compounds in electroplating wastewater, so that the water quality of the effluent achieved national level of discharging standard.