Abstract: A method of and a system for removing miniuscule solid particles from liquid wherein the liquid to be processed is supplied to one end of at least one filter element which may be a porous tube filter open at opposite ends and formed with a multiplicity of tiny openings in its wall having a first surface and a second surface. The liquid flows along the first surface and a portion thereof is passed through the tiny openings from the first surface side to the second surface side because of the latter being under lower pressure than the former, to be drawn off as filtrate. The rest of the liquid or a concentrated liquid portion flows out of the other end of the filter element. The flow velocity F of the liquid flowing along the first surface and/or the flow velocity f of the filtrate through the tiny openings is controlled such that the ratio F/f can be kept at a predetermined value.