Apparatus for treating materials, the apparatus including: a main body which includes an elongated retort section having a primary treatment chamber therein; a feed inlet at an upstream end of the retort section; a discharge outlet at a downstream end of the retort section; a material transfer device disposed within the primary treatment chamber to transfer material through the retort section; a filtering section with a filtering chamber therein which is in communication with the primary treatment chamber, the filtering chamber comprises an intake zone which receives gases from the primary treatment chamber, a filtering zone and a plurality of filters disposed within the filtering zone and arranged so that filtered gases can be passed to a collecting chamber, the filtering chamber being disposed laterally with respect to a longitudinal axis of the retort section which extends between the ends of the retort section and is spaced from the upstream end; characterised in that the main body includes the filtering section therein; the intake zone includes: a baffle plate to separate the intake zone from the filtering zone with a transfer passage providing communication therebetween the baffle plate being positioned to facilitate separation of the particulate matter from the gasses and to direct particulate matter towards the discharge outlet of the retort section a plurality of fins or plates on the inner wall of the filtering section and baffle plate which tend to deflect particulate matter towards the outlet, wherein the fins or plates also disrupt the providing communication therebetween the baffle plate air flow which reduces the velocity of the gases and a plate disposed at the top of the filtering chamber to direct the flow of gas towards the bottom of the filtering chamber towards the discharge outlet. a main body which includes an elongated retort section having a primary treatment chamber therein; a feed inlet at an upstream end of the retort section; a discharge outlet at a downstream end of the retort section; a material transfer device disposed within the primary treatment chamber to transfer material through the retort section; a filtering section with a filtering chamber therein which is in communication with the primary treatment chamber, the filtering chamber comprises an intake zone which receives gases from the primary treatment chamber, a filtering zone and a plurality of filters disposed within the filtering zone and arranged so that filtered gases can be passed to a collecting chamber, the filtering chamber being disposed laterally with respect to a longitudinal axis of the retort section which extends between the ends of the retort section and is spaced from the upstream end; characterised in that the main body includes the filtering section therein; the intake zone includes: a baffle plate to separate the intake zone from the filtering zone with a transfer passage providing communication therebetween the baffle plate being positioned to facilitate separation of the particulate matter from the gasses and to direct particulate matter towards the discharge outlet of the retort section a plurality of fins or plates on the inner wall of the filtering section and baffle plate which tend to deflect particulate matter towards the outlet, wherein the fins or plates also disrupt the providing communication therebetween the baffle plate air flow which reduces the velocity of the gases and a plate disposed at the top of the filtering chamber to direct the flow of gas towards the bottom of the filtering chamber towards the discharge outlet. a baffle plate to separate the intake zone from the filtering zone with a transfer passage providing communication therebetween the baffle plate being positioned to facilitate separation of the particulate matter from the gasses and to direct particulate matter towards the discharge outlet of the retort section a plurality of fins or plates on the inner wall of the filtering section and baffle plate which tend to deflect particulate matter towards the outlet, wherein the fins or plates also disrupt the providing communication therebetween the baffle plate air flow which reduces the velocity of the gases and a plate disposed at the top of the filtering chamber to direct the flow of gas towards the bottom of the filtering chamber towards the discharge outlet.