In operation, fresh chemicals are injected into raw water being pumped at a constant rate into the clarifier center mixing well where it is contacted and mixed with recycled chemicals and solids pumped from the sludge blanket by a recirculation pump. The coagulated water is distributed to a larger flocculation well where the chemical reactions forming insoluble floc particles are completed. The particles increase in size as they contact and adhere to each other. 

As the flocculation process proceeds and the particles grow, they become heavy and sink toward the bottom of the clarifier forming a sludge blanket. At this time the floc will capture small impurities in the raw water by electromotive attraction and simple entrapment. The positive ions formed by the chemical flocculent neutralize the natural negative potential of particulate material in surface waters allowing the particles to agglomerate.  Some of this sludge is recirculated to act as a flocculent aid, providing solids to initiate floc formation, and to reduce the amount of new chemical required by recycling.  Settled water rises to the surface outside the flocculation well where it is collected by submerged orifices in effluent troughs and is transferred to the filter feed piping. 

Fresh chemicals are introduced into the rapid mix tank with the raw water. This flash mixing initiates coagulation of the chemicals and is very important in obtaining good results.