Uncertainty Studies in Determination and Assessment of Acute Toxicity of Waste water and Its Improvement Method
Comprehensive biotoxicity indicators have been considered into environmental impact assessment system of wastewater treatment and discharge in China.However,the traditional methods of biotoxicity assessment face two risks of incorrect acceptance and incorrect rejection.According to Accreditation Criteria for the Competence of Testing and Calibration Laboratories(CNAS-CL01:2018),laboratories should consider the risks when making conformity assessment.This study investigated the uncertainty evaluation of the luminescent bacteria test for the acute toxicity of wastewater,involving its conformance,uncertainty,and non-conformance zones(Geometrical Product Specifications(GPS)—Inspection by Measurement of Workpieces and Measuring Equipment—Part 1:Decision Rules for Verifying Conformity or Nonconformity with Specifications(ISO 14253-1:2017)),using the pharmaceutical wastewater sample close to the discharge limits.The results show that the conformance,uncertainty,and non-conformance zones varied depending on the r-value of the standard curve and the precision of the measurement.The conformance zone decreased and uncertainty zone increased with the |r|-value or the precision decreased,which made it impossible to reduce the risk of incorrectly decision by setting a"guard band",and greatly affected the accuracy of the acute toxicity assessment.To solve this problem,a Welch's t-test was introduced to assess whether the acute toxicity of wastewater was conformance by comparing the relative luminosity of the wastewater with that of the 0.07 mg·L-1 HgCl2 solution.If the relative luminosity of the wastewater was higher than that of the 0.07 mg·L-1 HgCl2 solution,the acute toxicity of the wastewater was conformance,otherwise the acute toxicity of the wastewater was non-conformance.This study clarifies the limitations of the national standard method and the acute toxicity assessment by carrying out the uncertainty study,and proposes an improvement,which provide an important basis for the scientific assessment of the acute toxicity of wastewater.
assessment of acute toxicity of wastewaterluminescent bacteria testHgCl2 equivalent concentrationuncertainty zone
万方数据
维普
