ENH 222 Lecture Notes - Lecture 7: Septic Tank, Biochemical Oxygen Demand, Waterborne Diseases

67 views4 pages

rosebuffalo571

22 Apr 2018

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Waterborne pathogens may be difficult to culture or detect. May not have proper lab equipment or contaminant level. Quick affordable tests for water quality monitoring required. Used to detect fecal contamination of water. Ferments lactose with acid and gas within 48 hours. Presence indicates possible presence of pathogens or fecal pollution. Less reliable as a fecal pollution indicator but preferred as an indicator of treatment in drinking water. No detectable total coliform bacteria per 100 ml in drinking water. 1000 total coliform bacteria per 100 ml in recreational water. When amount of bacteria present is low. Filter larger volume of water through membrane. Specially formulated screen filters made of cellulose acetate. Pore sizes on these filters can be regulated and microorganisms are trapped on the surface of screen filters. Count red colonies on agar containing lactose at 35c for 24 h. Viruses and protozoans resistant to chemical disinfection. Ontario drinking water quality standards for portable water.

Related Questions

Case Study:

Bacteria are everywhereâon our skin, in our food, suspended in our drinking water. Although the
microbial majority is benign, a few bacterial species can make us sick. To safeguard against food- and
water-borne disease, microbiologists routinely screen our drinking water for bacterial pathogens.
Animal feces contain coliform bacteria, microorganisms that inhabit the intestines of warm-blooded
animals. Many coliform bacteria are also found on plants and in soil and water. Coliform bacteria are
not pathogens themselves, but their presence indicates the possibility of finding pathogens. In contrast,
fecal coliform bacteria such as Escherichia coli are found in feces, and their presence in drinking water
indicates fecal contamination. E. coli can also be a pathogen itself, so if E. coli is found in drinking
water there is a good chance that other pathogens are present, too.1
To detect E. coli and other coliform bacteria, microbiologists filter water samples and place the filter in
a Petri dish containing growth medium such as Endo agar. Microorganisms from the water grow and
form colonies, giving an estimate of the number of bacteria in each milliliter of water.
While E. coli forms colored, shiny colonies on Endo agar, other coliforms grow as white or clear
colonies.

Dark colonies = E. coli
White/clear colonies = coliform bacteria
White + Dark colonies = total coliform
bacteria.

The guidelines of maximum allowable limits for total coliforms in drinking and recreational waters vary
by state. Representative limits appear in the table below.2, 3, 4

Table 1. Maximum allowable limits of fecal coliform bacteria
(cells/100 ml)

	Total Coliforms	E. Coli
Drinking Water	0	0
Recreational Waters	400	235

Questions
1. Why would we want to count the number of fecal coliforms in a water sample?
2. Do 400 coliforms per 100 milliliters strike you as very many?
3. How many other types of bacteria might be present in a normal water sample?
4. What problems might Mary encounter when she uses these techniques in Antarctica?

You are working for the county health department this summer, and your job is to regularly survey the local beaches for microbial contamination.

Describe 3 tests you may use to analyze the water quality in these recreational areas.

You identify high levels of Enterobacter species in a sample one day. Summarize how you will convey this information to the beach supervisor who asks, âAre we shutting down today?â

Explain why there is little tolerance for fecal coliforms in drinking or recreational water.

redant669

You are working for the county health department this summer, and your job is to regularly survey the local beaches for microbial contamination. A. Describe 3 tests you may use to analyze the water quality in these recreational areas. B. You identify high levels of Enterobacter species in a sample one day. Summarize how you will convey this information to the beach supervisor who asks, âAre we shutting down today?â C. Explain why there is little tolerance for fecal coliforms in drinking or recreational water.

coppercockroach578

ENH 222 Lecture Notes - Lecture 7: Septic Tank, Biochemical Oxygen Demand, Waterborne Diseases

Document Summary

Get access

Related Documents

ENH 222 Final: Learning Objectives for lecture 7 for final exam

BIOL 2P98 Lecture Notes - Lecture 23: Fecal Coliform, Pathogenic Escherichia Coli, Indicator Organism

11:680:390 Lecture Notes - Lecture 24: Macconkey Agar, Norovirus, Coliform Bacteria

Related Questions