Methodological Research and Comparison for Determining Fecal Coliforms in Sewage Sludge with Enzyme Substrate Method
In order to improve the detection efficiency of fecal coliforms,a microbiological index of sludge,and verify the feasibility and adaptability of using enzyme substrate methods to detect this index,methodological research and comparative experiments were conducted.The enzyme substrate method and the manifold zymotechnics method were used for the synchronous detection of fecal coliforms in sludge.Data processing and paired t-tests were conducted by using SPSS software.The comparative analysis of 201 groups from six laboratories across China revealed:P=0.141(＞0.05)and correlation coefficient of r=0.964,indicating high correlation and no statistically significant difference between the two detection methods.According to six experimental groups conducted by three laboratories,six repeated measurements were conducted on samples with low,medium,and high concentrations,as well as samples prepared with certified reference materials.The results of these laboratories showed:The relative standard deviation ranged from 4.5％to 13.7％,1.6％to 6.7％,1.4％to 3.6％,and 1.1％to 4.5％,respectively;and the relative standard deviations among these laboratories were 8.7％,5.2％,5.3％,and 3.1％,respectively;the repeatability limits were 0.44,0.39,0.43,and 0.27,while reproducibility limits were 0.44,0.49,0.81,and 0.31,respectively.The relative error range of the laboratory was 0.91％to 2.8％,resulting in a final value of relative error of 1.9％±1.5％.Experiments results indicated that the precision and accuracy of the enzyme substrate method for determining fecal coliforms in sludge met the required standards,with a confirmed detection limit of 10 MPN/g.The manifold zymotechnics method and the membrane filtration method serve as current national and industry standards for detecting fecal coliforms in sludge,and the enzyme substrate method distinguishes itself with its simplicity,high accuracy,elimination of confirmation testing,and efficiency.Given these advantages,the enzyme substrate method can be used as a supplementary method for determining fecal coliformsin sludge.
国家科技期刊平台
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