A wastewater sample with an initial dissolved oxygen (DO) concentration of 8 mg/L is incubated in a BOD bottle at 20°C for 5 days. After incubation, the DO concentration decreases to 3 mg/L. Calculate the BOD₅ of the wastewater sample.a.50 mg/Lb.250 mg/Lc.5 mg/Ld.25 mg/L◄ Previous page
Question
A wastewater sample with an initial dissolved oxygen (DO) concentration of 8 mg/L is incubated in a BOD bottle at 20°C for 5 days. After incubation, the DO concentration decreases to 3 mg/L. Calculate the BOD₅ of the wastewater sample.a.50 mg/Lb.250 mg/Lc.5 mg/Ld.25 mg/L◄ Previous page
Solution
The Biochemical Oxygen Demand (BOD₅) is a measure of the amount of oxygen that bacteria will consume while decomposing organic matter under aerobic conditions. It is used as a measure of the degree of water pollution.
The BOD₅ is calculated by subtracting the final DO concentration from the initial DO concentration.
In this case, the initial DO concentration is 8 mg/L and the final DO concentration after 5 days is 3 mg/L.
So, the BOD₅ is calculated as follows:
BOD₅ = Initial DO - Final DO BOD₅ = 8 mg/L - 3 mg/L BOD₅ = 5 mg/L
So, the BOD₅ of the wastewater sample is 5 mg/L. Therefore, the correct answer is c. 5 mg/L.
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