DISINFECTING CONTAMINATE

D WATER

By: Ansis Mannie S. Rondina Harmony Science Academy–North Austin

Science Instructor – Mr. Ozan Basturk

PURPOSEWater is a basic necessity of human life. There are currently many waterborne diseases that can cause sickness. It is because of the presence of bacteria, parasites, and viruses. Some common bacteria that are contaminating the water are E.coli, Shigella, Salmonella, and V.cholerae. There are helpful ways to get rid of these disease causing bacteria. Solar disinfection, chemical treatment, and boiling are some of the methods used to disinfect contaminated water. The goal of this project is to find the best way to disinfect contaminated water. PROBLEMWhat is the best method in disinfecting contaminated water?

VARIABLESINDEPENDENT

VARIABLEDEPENDENTVARIABLE

CONTROLLEDVARIABLE

.

Disinfection method (Solar disinfection, Chemical treatment, Heating to boiling point)

Amount of bacterial growth in colonies after hours of incubation ( CFU/ml )

Same source of water for testing (contaminated water) Same volume of water sample sample (1 liter) for SODIS, Chemical treatment & Boiling Same type of agar (blood agar) Same type of calibrated dropper Same type of wire loop Reading results of same time interval ( after 24, 48, and 72 hrs. incubation)

“The many variables above can determine the amount of bacterial growth, so to insure a fair test an untreated water sample was used as a basis for comparison.”

HYPOTHESIS

Heating contaminated water to boiling temperature of 100 degrees centigrade will remove most of water borne bacteria.

MATERIALS & EQUIPMENT 2 Jug 1000 ml 4 pcs. 1 liter Plastic bottles Household bleach 4 pcs. Calibrated dropper 4 pcs. Blood agar Non CO2 Incubator @ 35°C Calibrated inoculating loop 0.001 ml Pot Stove

1. First set up is Solar disinfection(SODIS)

(copyright protected by scientist Ansis)

2. Second set up is Chemical treatment.

(copyright protected by scientist Ansis)

3. Third set up is Heating to boiling point.

(copyright protected by scientist Ansis)

EXPERIMENTAL PROCEDURE

4. Testing all samples (SODIS sample 1, chemical treated sample 2, boiling sample 3, and untreated sample 4). Always follow safety in laboratory.

(copyright protected by scientist Ansis)

Continuation:

SODISWater

CFU/ml

Chemical Treated Water

CFU/ml

BoiledWater

CFU/ml

UntreatedWater

CFU/ml

After24 Hrs.

Incubation5,000 NG NG 7,000

After48 Hrs.

Incubation7,000 1,000 NG 10,000

After72 Hrs.

Incubation9,000 2,000 NG 13,000

BACTERIAL GROWTH AFTER INCUBATION

NG = No GrowthOne Colony = 1000 CFU/ml ; CFU = Colony Forming unit

Afte

r 24

Hrs. I

ncub

atio

n

Afte

r 48

Hrs. I

ncub

atio

n

Afte

r 72

Hrs. I

ncub

atio

n0

2,0004,0006,0008,000

10,00012,00014,000

SODIS WaterChemical Treated WaterBoiled WaterUntreated Water

BACTERIAL GROWTH AFTER INCUBATIONC

FU

/ml

NUMBER OF HOURS INCUBATION

One Colony = 1000 CFU/ml ; CFU = Colony Forming unit

CONCLUSIONMy hypothesis was that heating contaminated water to boiling temperature of 100 degrees centigrade would remove most of water borne bacteria. It was supported by my results. My experiment went smoothly and encountered no problem except for time because I have to be consistent in reading my results every 24 hrs. incubation interval. I have to rush to the laboratory on my designated incubation time..

A further study would be interesting about finding an economical way to treat water like Slow sand filtration and Oxidant disinfection.

RESULTSAccording to my experiments, boiling (independent variable) the contaminated water showed no bacterial growth (dependent variable) after 24, 48, and 72 hours incubation but Solar disinfection (SODIS) showed bacterial growth in the agar plate by 5,000 CFU/ml after 24 hrs. incubation, 7,000 CFU/ml after 48 hrs. incubation, and 9,000 CFU/ml after 72 hrs. incubation. The medium is Chemical treatment. It had no growth in the first 24 hrs. incubation, but growth showed 1,000 CFU/ml and 2,000 CFU/ml after 48 and 72 hrs. incubation respectively. I also used an untreated sample as a basis for comparison that showed large amount of bacterial growth, 7,000 CFU/ml, 10,000 CFU/ml, and 13,000 CFU/ml in every 24 hrs. incubation interval.

BIBLIOGRAPHY1. McPherson, R. A. & Pincus, M. R. (2006), Henry’s Clinical Diagnosis and

Management Laboratory Methods 21th Edition, Saunders2. Murray P. R. (2007), Manual of Clinical Microbiology 9th Edition, Washington,

D.C.: ASM Press3. Ram P. K. & Blanton E. (2007, April 1), Household Water Disinfection,

American Journal of Public Health, 97, 130-135.4. Mc Guican K. G. & Joyce T. M. (1999), Solar Disinfection, Journal on Medical

Microbiology, 48, 785-787.5. Luby S. & Gangarosa E. (2007) Low Cost Intervention for Cleaner Drinking

Water, International Journal of Infectious Diseases, 5, 144-150.

ACKNOWLEDGEMENTI would like to thank Ms. Jan M. Lebourgeois, Supervisor of Microbiology, Laboratory Department, North Austin Medical Center and its entire staff for the help and for allowing me to use the facility and its equipment. You made my experiment a success.