Surface Environment, Mine Ventilation and Underground Hazards · Surface Environment · 2 marks · Numerical answer
A15 mL wastewater sample is diluted to300 mL and incubated for5 days at20°C. Dissolved oxygen drops from9.2 to4.4 mg/L. Find sample BOD in mg/L as an integer.
The oxygen depletion in the diluted bottle is9.2−4.4=4.8 mg/L. Sample fraction is15/300=0.05. Correcting for dilution gives BOD₅=4.8/0.05=96 mg/L, assuming the stated test requires no blank or seed correction.
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