Answer:
1. Chlorine
•advantages
-effective on a wide variety of bacteria
-highly effective
-not affected by hard water
-generally inexpensive
•disadvantages
-irritating to the skin
-effectiveness decreases with increasing pH of solution
-deteriorates during storage and when exposed to light
-dissipates rapidly
-loses activity in presence of organic matter.
2. Iodine
•advantages
-forms brown color that indicates strength
-not affected by hard water
-less irritating to the skin than the chloride
-activity not lost rapidly in the presence of organic matter
•disadvantages
-effectiveness decreases greatly with the increase in pH most active at pH 3.0
-very low acting at ph 7.0
-should not be used in water that is at 120°F or hot water
-make discolor equipment & services
3. Quaternary ammonium compounds
•advantages
-non-toxic,odorless,colorless,non-corrosive,nonirriting,stable to heat and relatively stable in the presence of organic matter,active over a wide ph range
•disadvantages
-slow interaction of microorganism
-not compatible with some detergents and hard water
