石灰铝盐沉淀法去除焦化废水氯离子的影响因素研究

Study on factors affecting chloride ions removal in coking wastewater by lime aluminium salt sedimentation

为了降低焦化废水生化处理出水的氯离子浓度,达到节水回用的目的,采用石灰铝盐沉淀法去除氯离子。试验考察了反应温度、反应时间、初始pH值、药剂添加比例、二次除氯等因素对氯离子去除率的影响,并采用XRD手段对反应沉淀产物进行了表征。结果表明:在反应温度为25℃、反应时间为2 h、n(Ca^(2+))∶n(Al^(3+)):n(Cl-)=22.50∶10∶1、不调节废水pH值的条件下,氯离子质量浓度由1083.31降至189.53 mg/L,去除率达到82.5%,SO_(4)^(2-)和色度去除率分别为98.2%、95.8%,经过二次除氯后氯离子去除率达到95.3%,水质达到GB/T 19923—2005《城市污水再生利用工业用水水质》标准。反应沉淀产物主要由弗雷德盐Ca_(2)Al(OH)_(6)Cl·2H_(2)O、Ca_(4)Al_(2)O_(6)Cl_(2)·10H_(2)O,钙铝盐Ca_(3)Al_(2)(OH)12,钙矾石Ca_(6)Al_(2)(SO_(4))3(OH)_(12)·26H_(2)O组成。

In order to decrease chloride ions concentration in the effluent water from coking wastewater biochemical treatment unit,so as to achieve the goal of water saving and recycling,lime aluminium salt sedimentation process was adopted to remove chloride ions.The influence of reaction temperature,reaction time,initial pH value,drug addition ratio,secondary chloride removal and some other factors on chloride ions removal were investigated through the test,and the reaction sediment was characterized by XRD method.The results showed that,under the condition that the reaction temperature was 25℃,the reaction time was 2 h,n(Ca^(2+))∶n(Al^(3+))∶n(Cl-)=22.5∶10∶1,no pH adjustment,the mass concentration of chloride ions decreased from 1083.31 to 189.53 mg/L with a removal rate of 82.5%,besides,the removal rates of SO_(4)^(2-)and chroma were 98.2%and 95.8%respectively.Through the secondary chloride ions removal,the removal rates of chloride ions reached 95.3%,the water quality met the requirement of GB/T 19923—2005 The reuse of urban recycling water-Water quality standard for industrial uses.The reaction sediment was composed of Ca2Al(OH)_(6)Cl·2H_(2)O,Ca_(4)Al_(2)O_(6)Cl_(2)·10H_(2)O,Ca_(3)Al_(2)(OH)_(12) and Ca_(6)Al_(2)(SO_(4))3(OH)_(12)·26H_(2)O.