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Environment & Health

Question
4 out of 72
 

Regarding purification of water all are true except



A Multiple tube method is used for sampling

B E. Coli can be tested by Indole test

C Clostridial infection indicate recent infection

D Level of residual chlorine should be 0.5mg/L

Ans. C Clostridial infection indicate recent infection Ref: Park; 22nd edi, pg – 669-670

Clostridial infection or Cl.perfringens to be more precise regularly occurs in feces though in much smaller numberas compared to E.coli. the spores are capable of surviving in water for a longer time than organisms of coliform group and usually resist chlorination at doses normally used in waterworks practice. Hence their presence in water denotes that fecal contamination has occurred and their presence in absence of coliforms denotes that contamination occurred at some remote time.

Multiple tube method also known as presumptive coliform test is used for bacteriological surveillance of water samples. E.coli can be tested by indole test and is the only organism producing gas from lactose at 44 degree C.

Level of residual chlorine must be 0.5mg/L in the water for successful chlorination.

Environment & Health Flashcard List

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