Coliforms and UV Disinfection: CE 360 Laboratory Exercise 10

Posted: August 26th, 2021

Coliforms and UV Disinfection: CE 360 Laboratory Exercise 10

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Coliforms and UV Disinfection: CE 360 Laboratory Exercise 10

Data Analysis (20 Points)

1. Complete the data recording table. Comment on the data. Which dilution produced a number of colonies within the acceptable range?

The dilution with acceptable number of colonies within acceptable range is the Drinking Water 100 mL B.

• Observe growth (if any) in your blanks.  Comment on these as well as sources of error in the methods used.

The results are fairly reliable. However, sources of error may include poor lighting that affects distinguishing of colors and failure to obtain test within the standard time that affects ultimate results. It affects results with different water chemistry.

• Based on the measured results what is your best estimate of the in Illinois River water?

CFU/100 ml = (120*100)/25 = 480 units.

• Comment on the effectiveness of the UV apparatus in deactivating coliforms.

Ultra-violet radiation is suitable for inactivating sporous ad vegetative types of bacteria such as cysts, Cryptosporidium cysts and Giadia lambia, among other pathogens. However, it is not effective for water that has amounts of coliform, suspended solids or substantial color.

• Comment on the swab results.

The use of coliform swabs offers the simplest approach to detect coliform pathogens in water.

Questions (30 Points)

1. Why are coliform considered “indicator” organisms? What properties make coliform a good indicator?

Coliform bacteria are considered “indicator” organisms because they are tested using simple tests and they can be easily detected even in low forms. The coliform bacteria can survive for long in water, a property that makes them a good indicator for existence of other pathogens in water.

• What is the difference between the sources of coliforms and fecal coliforms (FC)? Where can each be found? Name one example of a fecal coliform.

Coliforms and fecal coliforms sources differ in terms of temperature. Fecal coliforms can be found in poorly treated municipal sewerage and urban storm water while coliforms are found in common water sources.  An example of fecal coliform is the E.Coli.

• Discuss the outbreak of Cryptosporidium parvum in Milwaukee using reputable online resources.
  • How many people were affected? What was the predominant symptom of the infection? How many people died due to the outbreak?

During the outbreak at Milwaukee, about 400,000 people were infected and an estimated 100 people died. The predominant symptoms for Cryptosporidium parvum were watery diarrhea, abdominal cramps and headache.

• How was it discovered that something was wrong? What was the immediate course of action to avoid further illness?

The outbreak was discovered following a widespread sickening among people with diarrhea. The immediate action was to evacuate people out of the area and stop use of water from the affected plants. Further, people were advised to boil or disinfect water before us.

• Is Cryptosporidium a virus, bacteria, animal, or protozoa (hint: it’s a protozoa)? Why are some strains of Cryptosporidium dangerous? I.e. why do we worry about Cryptosporidium more than other pathogens in the context of modern U.S. drinking water treatment systems?

Cryptosporidium is a protozoa. Some strains of Cryptosporidium are dangerous because they can cause serious illness and even death especially to people with low immunity.

• On google maps (or apple maps if you must), locate the Kinnickinnic River in Milwaukee. Note that unlike the Chicago River since 1900, the Kinnickinnic flows into Lake Michigan. With the satellite view, zoom in on Jones Island. What do you see?

Figure 1: Figure Seen on John’s Island

• Note that both the northern and southern drinking water treatment plants in Milwaukee draw from Lake Michigan via large underground, and then deep underwater, intake pipes that protrude out into the lake. Also note that there is generally a counterclockwise current in Lake Michigan. From which plant, north or south, do you think the contamination originated? What was the source of the contamination? Note that this plant was shut down for 2 months, with the other plant supplying all of the city’s water in the interim.

The contaminated must have originated from the north plant. The source of contamination was probably due to the counterclockwise current in Lake Michigan.

• What does the Milwaukee drinking water treatment plant do now to prevent another outbreak?

In order to prevent other outbreaks, Milwaukee drinking water treatment should strengthen the protection of water sources using strong barriers, ensure constant disinfection and proper filtration.

Appendix

Data Recording

#	Sample	Location Collected	Dish Label	Coliform Count	Observations
1	Drinking Water 100 mL A	Bathroom by Jobst 215	DW-A	0	Completed
2	Drinking Water 100 mL B	Water Fountain by 208	DW-B	0	Completed
3	Blank: Dilution water only	DI Faucet in Env. Eng. Lab	Blank	2	Completed
4	IL River Water 1 mL diluted in in 100 mL DI	River shore in downtown Peoria	ILR – 1	7	Completed, low content
5	IL River Water 5 mL diluted in in 100 mL DI	River shore in downtown Peoria	ILR – 5	64	Completed, with moderate content
6	IL River Water 25 mL diluted in in 100 mL DI	River shore in downtown Peoria	ILR – 25	120	Completed, high content
7	IL River Water 1 mL diluted in in 100 mL DI Sample passed through UV	River shore in downtown Peoria	ILR – 1 UV	0	Completed
8	IL River Water 5 mL diluted in in 100 mL DI Sample passed through UV	River shore in downtown Peoria	ILR – 5 UV	20	Average content, completed
9	IL River Water 25 mL diluted in in 100 mL DI Sample passed through UV	River shore in downtown Peoria	ILR – 25 UV	70
10	Swab 1		Swab 1	0
11	Swab 2		Swab 2	0	Damaged filter
12	Swab 3		Swab 3	0
13	Swab 4		Swab 4	0