Sewage is flowing with a velocity of 0.90 m/sec in a 300 mm diameter sewer running full. Find the hydraulic gradient assuming Manning's rugosity coefficient η as 0.013.

Turbidity in water is measured on which standard scale?

Mudball formation in rapid sand filters is the result of:

In a water sample, if 2 mg of platinum cobalt salt is dissolved in 1 litre of distilled water, then the colour produced is equal to: