Q1: The discharge per unit plan area of a sedimentation tank, is generally called

ANS:D - all the above.

1. Overflow Rate: This term refers to the rate at which water overflows from the sedimentation tank. It is typically expressed in units such as gallons per minute per square foot or liters per second per square meter. Overflow rate is an important parameter in the design and operation of sedimentation tanks because it helps ensure that the flow of water through the tank is controlled and optimized for effective sedimentation and clarification.
2. Surface Loading: Surface loading, also known as hydraulic loading or hydraulic surface loading, refers to the rate at which wastewater is applied to or flows over the surface area of a treatment unit, such as a sedimentation tank. It is expressed as the volume of wastewater treated per unit area of the tank's surface per unit time (e.g., gallons per day per square foot or cubic meters per hour per square meter). Surface loading is a critical parameter in the design and operation of sedimentation tanks because it influences the settling characteristics of suspended solids and affects the overall efficiency of the sedimentation process.
3. Overflow Velocity: This term refers to the velocity at which water overflows from the sedimentation tank. It is typically calculated by dividing the flow rate of water leaving the tank by the cross-sectional area of the overflow weir or outlet. Overflow velocity is an important consideration in the design and operation of sedimentation tanks because it helps determine the hydraulic performance of the tank and ensures that water flows smoothly out of the tank without causing turbulence or other disruptions to the sedimentation process.