How to check the bacterial contamination in drinking water by testing sulphide ion?
Answers
Sulphide ion test is a good test to check the bacterial contamination in drinking water. to test the water for bacterial contamination, fill it in the bottle with H2S strip in it and incubate it at 35oC for 14 to 16 hours. if the strip turns black than that is the sign that water is highly contaminated with bacteria and is unfit for human consumption.
What actually happens in this test is that hydrogen sulphide is formed in surface waters by the deficiency of oxygen or by the decomposition of organic compounds having sulphur. The amount of sulphide ions increases when the pH is 10 or more than 10. While in acidic conditions, the hydrogen sulphide concentration increases which dissociates to form hydrosulphide HS- and sulphide ions S2 ions. hydrogen sulphide is not only toxic to fish but it also reduces aesthetic value of water by foul colour. hence these conditions favour the bacterial growth and contamination and this condition can be detected by H2S strip.