HIGH RATE SOLID CONTACT CLARIFICATION (HRSCC) Water clarification is the process of removing suspended solids, turbidity, colloids from water. The HRSCC has been designed such that coagulation, flocculation, setting and sludge remove are combined in a single tank. HRSCC are designed to treat different type of water for a various application for solid settling and separation. These units are tailor - made to suit various flow rates and can design for very large flows. For optimum operation effective solid separation HRSCC employs use of flash mixer, and stilling chamber prior to clarifier. Typically chemical treatment using Alum, Zinc and polyelectrolyte are used to aid coagulation &flocculation and enhance removal of solids.

HRSCC comprises of the following:

There are two drives in the HRSCC: one drives the sludge disposal rake and the other drives the turbine mixer which re circulates the sludge.

Coagulation, flocculation, setting and sludge removal is combined into a single tank. Concentrated solids, which have earlier settled in the clarifier, are recirculated to the mixing zone by the turbine and mixes with the incoming influent which has a relatively low concentration of suspended solids. The rate of flocculation is directly dependent on the solids concentration (by volume). Therefore by recirculating the settled floe, the amount of solids increases, thereby improving flocculation and hence the name Solids Contact Clarifier. This also results in lower requirement of coagulation chemicals since contact of this floc which has been formed earlier with new floc results in good growth of the same. This water then flows into the reaction well where the solids coagulate and settle. The flow passes through the sludge blanket at the bottom of the reaction well and this further removes suspended particles. The rotating rake arm moves the settled solids or sludge to the center of the clarifier for r emoval. The flow rises upward in the clarification zone and water is removed by the redial collection troughs on the surface. A portion of the settled sludge is periodically drawn off by opening the blow down valve. The recirculation of sludge result in the HRSCC producing water of very low turbidity for a wide range of inlet suspended solids level and even in conditions of low inlet turbidity.