Coliforms, Total, Fecal and E. coli - Hach Dilute samples that contain a high level of bacteria so that approximately 20 to 200 bacteria colonies grow on the membrane filter Use the steps that follow to make serial dilutions of the sample
NEMI Method Summary - 9222D Filter sample through a membrane filter Place membrane on mFC agar containing aniline blue as indicator Incubate at 44 5C for 22-24 h Colonies that are various shades of blue are positive for fecal coliforms The blue color indicates the capability to ferment lactose to acid
Parameter: Thermotolerant (Fecal) Coliform - Membrane Filtration . . . How is the sterile rinse dilution water prepared? [SM 9050 C-2015 (1) (a)] Add 1 25 mL stock Phosphate buffer solution and 5 0 ml magnesium chloride stock solution to 1-L reagent grade water 100 ml volumes or less autoclave for 15 minutes Rinse water volumes >100 ml adjust autoclave time for volume – see table 9020:IV SM 9020 B-2015
9222 MEMBRANE FILTER TECHNIQUE FOR MEMBERS OF THE COLIFORM GROUP* Do not use the MF technique to test wastewater receiving only primary treatment unless the sample is diluted, because the high turbidity level may quickly clog the membrane filter before sufficient sample is collected Chlorinated effluents should have low counts and turbidity
9222 MEMBRANE FILTER TECHNIQUE FOR MEMBERS OF THE COLIFORM GROUP When used for enumerating coliforms, the MF technique is a more precise method than the multiple-tube fermentation procedure, because it uses direct counts as opposed to a statistical estimation (MPN) of results; compare Tables 9221:3 and 9221:4 with Table 9222:3
Coliforms—Total, Fecal and E. coli - Fondriest Analyze total-coliform-positive potable water samples for the presence of fecal coliform or E coli Confirm fecal coliforms from a membrane filter positive for total coliforms by swabbing the membrane with a sterile cotton swab and inoculating a tube of EC Medium Broth
Membrane Filtration Guidelines - Hach Samples that contain a high level of bacteria must be diluted so that the bacteria that grows on the filter is at a density that can be measured Table 420 and Table 421 list recommended sample volumes for various types of samples Select a sample size to give 20 to 200 colony-forming units (CFU) per filter
How do I determine the density of total or fecal coliforms If more than one dilution, independently carry counts to final reporting units, then average for final reported value: Filter 1 volume = 0 1 mL CFU = 75 Filter 2 volume = 0 03 mL CFU = 30 (75 x 100) = 75,000 coliforms 100 mL, and 0 1 (30 x 100) = 100,000 coliforms 100 mL, then 0 03 (75,000 + 100,000) = 87,500 coliforms 100 mL 2