The generally sketchy performance information has been evaluated with respect to the micros training process. The present information base suggests strongly that solids balances, solids loadings and description of the type of cake formed can be examined as the basis for expressing empirically the behavior of the microstraining process. Two empirical relationships relating solids removal efficiency with (1) a solids loading factor, and (ii) a normalized hydraulic loading factor are proposed and substantiated using original data developed in separate studies on unsalted percolating filter effluents and clarified activated sludge effluents. The empirical relationships thus developed can be used to provide a basis for designing and operating the microstraining process. Application of such an approach would require establishing the values of the parameters and for the solids suspension of concern, a statement of the treatment objectives and operational constraints of the selected or designated machine.