Mechanism and feasibility of colloidal particle removal by a microcarrier process

Pollutants associated with colloidal particles in stormwater runoff have received increasing attention. Removal of these toxic particles is of paramount importance in regulating the quality of stormwater effluents. With the promulgation of the USEPA's Enhanced Surface Water Treatment Rule, a means for the removal of these particles in an efficient and rapid manner in treatment facilities is needed. This paper reviews the mechanisms and feasibility of a high rate sedimentation process in enhancing the settling in the flocculation-sedimentation approach. The advantages of microcarriers, namely, to enhance particle capture as well as rapid sedimentation, are presented. A series of microcarrier-jar tests was carried out. The experimental results reveal that the microcarrier process is effective in dramatically reducing treatment time and, in turn, reducing the size of treatment facility needed in a standard coagulation/flocculation unit operation.