BIOM-360 Lecture Notes - Lecture 20: Fecal Coliform, Indicator Organism, Settling Basin
2 May 2018
School
Department
Course
Professor
Applied and Environmental Microbiology
Purification and Sanitary Analysis Ensure Safe Drinking Water
Water can transmit viruses, parasites and other bad microbes.
Cryptosporidium: bacteria that causes diarrheal disease.
Steps to Water Purification
Suspended material → sedimentation basin
Want to get as much physical sediment out as we can.
Large particles settle out.
Partially clarified water mixed with chemicals such as alum and lime → settling basin
More material precipitates out in coagulation or flocculation process
Removes microbes, organic matter, toxic contaminants, and suspended fine particles.
Water → rapid sand fllters
Physically traps fine particles and flocs
Water treated with disinfectant
Chlorine
Concern about disinfection byproducts (DBPs) such as THMs may be carcinogens
Ozone: trivalent reactive oxygen
Water Purification and EPA Regulations
EPA Regulations called Long Term 2 Enhanced Surface Water Treatment Rule
Try for 100% removal of organisms.
Sanitary Analysis of Waters
Based on detecting indicator organisms.
“Ideal” indicator organism.
Coliforms and fecal coliforms.
Commonly Used Indicators: tend to be G- bacilli
Coliforms
Facultative anaerobic, G-, non-endospore forming, rod-shaped bacteria that ferment lactose with
gas formation within 48 hours at 35 degrees.
Traditional method of detection is multiple-tube fermentation test.
Fecal streptococci
Increasingly used to test brackish and marine water
Other Tests for Indicator Organisms
Membrane filtration technique
Used to detect total coliforms, fecal streptococci, and fecal coliforms.
From intestines of warm-blooded animals.
Detected by incubation @ 44.5 degrees.
