An Energy-dissipating inlet (EDI) is a device placed inside the feedwell.  It helps dissipate the energy (velocity) of incoming influent to promote flocculation. EDIs eliminate flow currents from occurring within the clarifier that tend to carry lighter floc material into the effluent, rather than settling out.  By slowing the flow, it prevents light biological flocs from being carried too far into the clarifier, creating better conditions for settling.