This is a Solid Contact unit where settled sludge is recirculated and mixed with the incoming stream in such a way that the already settled particles form a nuclei for particle growth through flocculation created by controlled hydraulic movement of the chemically conditioned inflow stream entering the Clarifier unit. To meet this purpose, this unit combines flash mixing, flocculation and sedimentation into a single unit for effective removal of suspended solids and other associated impurities.

One of the major advantages of Reactor Clarifier units is its smaller footprint as the desired overflow clarity can be achieved at high upflow rates which is achieved by optimum placement of the overflow launders - radially or circumferentially - in such a way that the water upflow remains as vertical as possible with minimum disturbance to solid settling. These units can be operated with or without sludge blanket requirement. The flocculation unit is provided with variable speed to adjust the conditions during varying process requirement in actual operation. The flocculation zone is separated from the Clarification zone physically through a metallic or non-metallic cone. Depending upon the size, the smaller units are provided with side feed entry whereas the larger units are provided with bottom feed. These units can be provided from small sizes and upto 50 M diameter & above.