Abstract Kinetic equations which describe the process of contact flocculation in solids contact clarifiers were proposed. Decrease of micro-flocs with the contact of high concentration and large diameter well-grown-flocs both in a turbulent flocculation chamber and in a floc blanket of upflow clarifier were discussed. First order equations with the micro-floc concentration were derived theoretically for both types of contact flocculation. By experiments, these kinetic equations were verified and their coefficients were evaluated. Finally, practical equations for the design of micro-floc removal process with the contact of well-grown-flocs both in a turbulent flocculator and in a floc blanket were proposed.