A five day B.O.D. at 15°C of the sewage of a town is 100 kg/day. If the 5 day B.O.D. per head at 15°C for standard sewage is 0.1 kg/day, the population equivalent is A. 100 B. 1000 C. 5000 D. 10000

The correct answer is B. 1000.

The population equivalent (PE) is a measure of the organic load of wastewater. It is calculated by dividing the five-day biochemical oxygen demand (BOD5) of the wastewater by the five-day BOD5 per capita of standard sewage. The five-day BOD5 is a measure of the amount of oxygen that is required to decompose the organic matter in the wastewater. The five-day BOD5 per capita of standard sewage is 0.1 kg/day.

In this case, the five-day BOD5 of the sewage of the town is 100 kg/day. Therefore, the population equivalent is 1000.

Option

Option C is incorrect because the population equivalent is not equal to the five-day BOD5 per capita of standard sewage.

Option D is incorrect because the population equivalent is not equal to 10000.