GATE Civil Engineering (CE) 2013 Solved Paper

A student began an experiment for the determination of 5-day, 20°C BOD on Monday. Since the 5^th day fell on Saturday, the final DO readings were taken on next Monday. On calculation, BOD (i.e. 7 day, 20°C) was found to be 150 mg/L. What would be the 5-day, 20°C BOD (in mg/L) (up to 2 decimal value)? Assume the value of BOD rate constant (k) at a standard temperature of 20°C as 0.23/day (base e). __________