Question

Look at the following relationship between concentration of free residual chlorine and contact time required for 99% kill (Watson's Law: C^0.86 t_p = λ (constant) for different pathogens).

Pathogen type	Adenovirus	E.coli	Coxsackievirus A2	AA
λ (Constant)	0.098	0.24	6.3	0.110

Which pathogen has maximum resistance for chlorination?

1. E.coli
2. Adenovirus
3. Coxsackievirus A2
4. AA

Answer 1

Correct Answer - Option 3 : Coxsackievirus A2

Explanation:

The pathogen in which case time required for disinfection is highest is the one with maximum resistance for chlorination.

C0.86 tp = λ

As λ is highest for Coxsackievirus A2, so from above equation t_p is also highest for Coxsackievirus A2. Hence it has maximum resistance.