水中化学需氧量的测定及不确定度的评定

Determination and Uncertainty Evaluation of Chemical Oxygen Demand in Water

对某污水处理厂排口中污染物化学需氧量进行测量,并对结果的测量不确定度进行评定。依据《水质化学需氧量的测定重铬酸盐法》和《测量不确定度评定与表示》,建立了测定水中化学需氧量的不确定度测量模型,并进行分析。结果表明:污水处理厂排口化学需氧量浓度为89 mg/L,整个分析过程带来的相对标准不确定度为0.804%,各测试环节中滴定终点的把握对测试结果准确性的影响较大。

The chemical oxygen demand of pollutants at the outlet of sewage treatment plant was measured and the uncertainty of the measurement results was evaluated.According to the standard methods of chemical oxygen demand and evaluation or expression of measurement uncertainty,the uncertainty measurement model for determination of chemical oxygen demand in water was established and analyzed.The results showed the concentration of chemical oxygen demand at the outlet of sewage treatment plant was 89 mg/L,and the relative standard uncertainty of the testing method was 0.804%.The determination of the titration end point had a great influence on the accuracy of the test results.