A 2% sewage sample (in distilled water) was incubated for 3 days at 27$$^\circ$$C temperature. After incubation, a dissolved oxygen depletion of 10 mg/L was recorded. The biochemical oxygen demand (BOD) rate constant at 27$$^\circ$$C was found to be 0.23 day$$-$$1 (at base e). The ultimate BOD (in mg/L) of the sewage will be ________. (round off to the nearest integer)
A water treatment plant has a sedimentation basin of depth 3 m, width 5 m, and length 40 m. The water inflow rate is 500 m3/h. The removal fraction of particles having a settling velocity of 1.0 m/h is ________. (round off to one decimal place) (Consider the particle density as 2650 kg/m3 and liquid density as 991 kg/m3)
With respect to fluid flow, match the following in Column X with Column Y:
| Column X | Column Y | ||
|---|---|---|---|
| P. | Viscosity | I. | Mach number |
| Q. | Gravity | II. | Reynolds number |
| R. | Compressibility | III. | Euler number |
| S. | Pressure | IV. | Froude number |
Which one of the following combinations is correct?
A rectangular channel with Gradually Varied Flow (GVF) has a changing bed slope. If the change is from a steeper slope to a steep slope, the resulting GVF profile is