Patent ID: 7014775

Claim:
A method comprising: (a) providing an in-line blender downstream of a sludge pump and upstream of a sludge dewatering apparatus, said in-line blender comprising (1) a blender housing, said blender housing having an inlet, an outlet, and a mixer mounting nozzle, (2) a mixer drive affixed to said mixer mounting nozzle, and (3) an impeller, mounted in cantilever configuration for rotation within said housing, said impeller having a rotating shaft extending along a longitudinal axis, from said mixer drive to a distal end, said impeller having a plurality of blades attached to said rotating shaft, said rotating shaft having an axially outermost blade and an axially innermost blade, said innermost blade having a proximal end located spaced apart from but closely adjacent said mixer drive, wherein said plurality of blades are configured to assure that, along the shaft axis, blades overlap lengthwise, so that within said housing, including from said proximal end of said innermost blade to said distal end of said rotating shaft, a bare rotating shaft is substantially avoided, so that by when in operation, ragging is prevented; (b) adjustably fixing the speed of the impeller of said in-line blender; and (c) combining an additive with said sludge at said in-line blender.