An improved method for removing solid particulate matter from the exhaust of a diesel engine, having the steps of passing the engine's exhaust flow through at least a part of filter means to trap solid particulate matter contained initially in the exhaust, thereby to remove said matter from said exhaust flow, periodically interrupting the exhaust flow through at least said part of the filter means, passing, during said interruption, at least one backflush fluid pulse through at least said part of the filter means thereby to dislodge from the filter means, and entrain, said solid particulate matter, and transporting said dislodged solid particulate matter to the intake of said engine so that said matter can be combusted in the engine, wherein the improvement comprises purge means advantageously positioned so as to allow the discharge of noncombustible particulate matter from the engine before it accumulates to a harmful level.