There is a strong correlation between fecal coliform numbers and e. coli numbers and this is highly dependant on the concentration of these organisms in the effluent.  The correlation becomes somewhat obfuscated towards the detection limit of the test (such as MPN<2 for multiple tube, <1.1 for Colilert) for the simple reason that you cannot run statistics on results that are <2 or <1.1.  I ran a comparison between multiple tube fermentation fecals and e. coli using Colilert and could not determine a correlation using typical effluent and this had to do with the above reason.  I ran a second study in which I spiked the effluent with secondary effluent in order to artificially introduce coliforms into the effluent.  There was no statistically signficant difference between the methods but could not generate a correlation due to the fact that the results generated are within a small tight cluster.  When comparing the two methods using belt press cake the correlation between methods was r=0.9584.  If you are interested in looking at the study I've attached the PDF.

With membrane filtration, I am sure that the correlation would be around the same.  You can try and get a hold of the following articles:

Chihara, R.J., M.A. Sullivan, Likirdopulos C.A., O.D. Simmons III, C.L. Burch, and M.D. Sobsey.  Comparison of methods for detection of fecal coliforms and E. coli in agricultural and municipal wastewater systems. Animal Waste Management Symposium, 2005.

Covert, T.C., L. C. Shadix, E.W. Rive, J.R. Haines, and R.W. Freyberg, Evaluation of the autoanalysis Colilert Test for Detection and Enumeration of Total Coliforms, 1989, Appl. Environ. Microbiol., 55:2443-2447.

Eccles, J.P., R. Searle, D. Holt, and P.J. Dennis, 2004.  A comparison of methods used to enumerate Escherichia coli in conventionally treated sewage sludge. Journal of Applied Microbiology 96:375-383.

E. coli happens!

Database Central

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	A Comparison of the Multiple Tube Fermentation Technique and Colilert for Enumerating E.pdf (305 views, 80.64 KB)