The Rotamix process mixing system uses solids-handling equipment and technology to provide hydraulic mixing systems for digesters, sludge storage tanks, sludge blend tanks, equalization basins and anoxic zones. The technology of the Vaughan chopper pump combined with an analyzed placement of fixed-position glass-lined mixing assemblies provides dual-zone mixing with a vertical-axis vortex, assuring uniform mixing velocities through a tank or basin.