化学需氧量(chemical oxygen demand, COD)作为表征污水或废水污染程度的一个重要指标,在全球范围内 被普遍采用.通过追踪COD方法发展的历史,以工业废水中最常用的重铬酸钾法为例,从氧化还原电位、催化作用等 方面分析方法原理的特点、影响因素与适用范围,结合氧化剂的选择、定义的科学性、二次污染、 COD成分的毒性以 及干扰组分的存在5 个方面讨论传统COD方法中存在的问题,指出方法创新和完善的方向;在方法原理基础上,论 述微波消解技术、分光光度技术、库仑滴定技术等方面的COD技术化及其实际应用的动态,提出实现流程的标准化 和样品的批量化可以提高效率的观点.通过对我国工业废水COD测定方法、技术应用的过程分析,指出COD方法及 技术的创新性、可靠性、时效性对于我国未来的工业废水污染控制的稳定性与水环境管理的规范性将发挥重要的影 响作用.
Chemical oxygen demand (COD) as an important indicator of water quality has been widely used for characterizing the pollution extent of sewage or wastewater. By tracking the history of COD analysis and taking the commonly -used potassium dichromate approach as an example, here the authors carry out a thorough review on (i) the principle of COD detection method,the key factors and the scope of its application; and (i i) the important issues related to the traditional method including the selection of oxidants, the scientific meaning of definition, the second pollution, the toxic components and the interferential components. In addition, we discuss the development and current status of the microwave digestion technology, spectrophotometry technology and Coulomb titration technology 袁 and propose the view of standardization and batch processing in order to improve the efficiency of COD determination. Lastly , we emphasize that the novelty, reliability, and timeliness of COD method/technology play significant roles in our country’s industrial wastewater pollution control and water environment management.