I have always favored the MF procedure for total and fecal coliforms. It
is easier to perform, gives more definitive results in a shorter time
frame and is more sensitive and accurate than the MPN in my opinion. There
is also a qualitative presence-absence test that is currently used in
drinking water analysis that can detect both total, fecal coliforms and E.
coli and correlates well to the quantitative MF test in terms of accuracy
of identification. Remember that the MF fecal coliform test should be
incubated at a well controlled 44.5 degrees and provides better
differentiation of fecal coliforms if a medium like M-FC is used.
As for the nitrogen and phosphorous, nitrogen can be determined using a
glass membrane instrument similar to a dissolved oxygen meter. Phosphorous
can be measured by selective ion electrode or ion exchange chromatography.
There are also wet chemical methods and spectrophotometric which can be
used. An excellent source for both the microbial and chemical methods is
"The Standard Methods for the Examination of Water and Wastewater".
Ecolife
