几种典型废水COD在线监测仪器适用性分析与选择

Performance comparison and Choice of Online CODMonitoring Instruments for several typical wastewater

水中化学需氧量(COD)是国家重点监测并控制的污染指标。COD在线监测仪是监控COD排放的重要手段,其数据可靠性直接影响所辖区域的环境管理决策。本文选取市场上可见的4类不同原理的COD在线监测仪器,分别测试漳州市6种典型废水,综合评价其适用性。结果表明,紫外吸收法(UV)应用范围较窄,燃烧法(TOC)、重铬酸钾-分光光度法(CODcr)和电化学法COD在线监测仪器的适用范围较广。但购置燃烧法(TOC)和电化学法在线监测仪器和日常维护费用较大,维护技术难度较大,数据需经实验室数据校准等诸多因素影响其在市场上应用。另外,重铬酸钾法在线监测仪器对高于4000 mg/L的氯离子的废水,存在显著的不适应性。因此,企业应根据自身实际废水具体情况,选择适宜测试原理的COD在线监测仪器。

As an important pollutant index,Chemical oxygen demand（COD）has become one of pollution reduction targets.COD monitoring instrument is an important way to monitor the emission of COD,and its data reliability directly affects the environment management decision of the area under its jurisdiction. Four different online COD monitoring instruments were used to comprehensively evaluate their monitoring performances,which was useful to choose suitable instruments for 6 different waters.The results indicated that the application range of ultraviolet absorption（UV）method is narrow,but the application range of combustion method（TOC）,bichrome-spectrophotometry（CODcr）and electrochemical method on-line monitoring instruments is wide. But the expensive purchase of TOC and electrochemical method online monitoring instruments and daily maintenance costs,difficulty of maintenance technology,data needing to be calibrated by laboratory and many other factors affectedtheir applications in the market. Moreover,the data of on-line monitoring instrument of CODcr has been significant influenced bythe chlorine ion of the wastewater which was higher than 4000 mg L-1.Therefore,the suitable COD on-line monitoring instrument should be chosen by the enterprise according to the actual wastewater.