An industrial process wastewater contains a mixture of metal fragments and sand. The metal fragments range in diameter from 0.5 to 10 mm with a speci?c gravity of 1.65. The sand particles range in diameter from 0.04 to 2.0 mm with a specific gravity of 2.65. The wastewater discharge rate is 1400 m3 /d at 20°C. Design a settling tank to remove all the metal and sand particles. If the depth of the tank is 2 m, calculate the detention time.