Superficial Liquid Up flow Velocity
Higher up flow velocities, favors better selective process for the sludge and improve mixing in the reactor. However, at very high up flow velocity, greater than1.0 to 1.5 m/h, the inoculum may get washed out during start-up or during normal operation granules may get disintegrated, and the resulting fragments can easily wash out of the reactor. The maximum liquid up flow velocity allowed in design should not exceed 1.2 – 1.5 m/h. Up flow velocities as 0.25 to 0.8 m/h are favorable for granule growth and accumulation, during normal operation of the reactor and maximum up flow velocity up to 1.5 m/h at peak flow conditions for short duration can be used in design.