Question

Water having dissolved oxygen content equals to $3.9mg/L$ may be considered as :-

• A. Non-Polluted
• B. Contaminated
• C. Moderately polluted
• D. Heavily polluted

Answer 1

The correct option is C Moderately polluted

BOD is normally revealed in either ppm values or in mg/L. Unpolluted waterways commonly have a BOD underneath 1 mg/L. Tolerably contaminated streams differ between 2 to 8 mg/L. Untreated sewage midpoints somewhere in the range of 200 and 600 mg/L while productively treated city sewage would be 20 mg/L or less.

So, the correct option is 'Moderately polluted'.