Determine the BOD5 for a 10 mL sample, collected from wastewater stream in Jamdoli that is diluted to a total volume of 300 mL when the initial dissolved oxygen is 8.5 mg/L and after 5 days, has been reduced to 2.5 mg/L.

The BOD5 (Biochemical Oxygen Demand over 5 days) is a measure of the amount of oxygen consumed by bacteria and other microorganisms while they decompose organic matter under aerobic (oxygen is present) conditions at a specified temperature.

Here's how to calculate it:

1. First, calculate the initial and final dissolved oxygen concentrations. The initial concentration is given as 8.5 mg/L and the final concentration after 5 days is 2.5 mg/L.

2. Subtract the final concentration from the initial concentration to find the amount of oxygen consumed. In this case, 8.5 mg/L - 2.5 mg/L = 6 mg/L. This is the amount of oxygen consumed in the 300 mL solution.

3. However, the BOD5 is usually expressed in terms of volume of the original sample, which is 10 mL in this case. So, we need to convert the oxygen consumed in the 300 mL solution to the equivalent amount in the 10 mL sample.

4. To do this, divide the volume of the diluted sample (300 mL) by the volume of the original sample (10 mL) to get the dilution factor. In this case, 300 mL / 10 mL = 30.

5. Multiply the amount of oxygen consumed (6 mg/L) by the dilution factor (30) to get the BOD5. In this case, 6 mg/L * 30 = 180 mg/L.

So, the BOD5 for the 10 mL sample collected from the wastewater stream in Jamdoli is 180 mg/L.