Abstract: The filtration system comprises a holding vessel and a filter for clarifying contaminated influent gas streams by passing the stream through the filter. The holding vessel has an inlet port for receiving the influent gas to be filtered and for draining the vessel and an outlet port for delivering the clean effluent for further processing. When the particulate matter has clogged the filter and increases the differential pressure across the filter such that it interferes with the normal filtration operation, the particulate matter is cleaned from the filter by isolating the holding vessel from the gas stream and introducing a liquid into the holding vessel and then by backwashing the liquid so that it flows through the holding vessel and the filter in the opposite direction of the influent gas. Backwashing the liquid from the holding vessel dislodges and removes the layer of solid particulate matter on the filter surface and the quantities of particulate matter trapped within the interior of the filter.