冶金工业含铬废水处理工艺优化及改造应用

Optimization and Application of Chromium Containing Wastewater Treatment Process in Metallurgy Industry

针对中部地区某钢铁厂的还原沉淀处理工艺存在出水总铬浓度不能稳定达标、药剂投加量大、铬泥产量高等问题,对其处理工艺进行升级改造。在原有工艺的基础上,优化二级还原池的ORP值并作为自控加药系统指标,改善絮凝阶段的水力条件,增加活性砂过滤系统,同时采用NaOH/Ca(OH)2组合方式调节中和池的pH值。工艺优化后,Cr(Ⅵ)和总Cr出水浓度平均值分别为0.02、0.07 mg/L,可以稳定达到《钢铁企业排放标准》(GB 13456—2012)中表3的相应指标要求,同时减少了还原剂投加量,铬泥产量显著下降,运行成本明显降低。

In order to solve the problems of unstable total Cr concentration in the effluent,large dosage of agents and high production of chromium sludge in the reduction-precipitation process of a steel plant in the central region,the treatment process of the plant was thus upgraded and reconstructed.Based on the original process,ORP value of the secondary reduction tank was used as an indicator of a selfcontrolled agents system,hydraulic conditions of the flocculation stage were optimized,and combination of NaOH/Ca(OH)2 was used to adjust the pH value of the neutralization tank.After optimization of the process,average concentrations of Cr(Ⅵ)and total Cr in the effluent were 0.02 mg/L and 0.07 mg/L,respectively,which reached the standard of table 3 in Discharge Standard of Water Pollutants for Iron and Steel Industry(GB 13456-2012).Meanwhile,dosage of the reducing agents and chromium sludge yield were decreased,and the operational cost was significantly reduced.