The disclosed mulcher has a base unit and a shredding blade in a removable assembly. Two different embodiments are disclosed. In both embodiments, shredded material is removed from air exiting the shredding blade before it reaches an exhaust port. In one embodiment, the material is removed by a filter. In the other embodiment, walls are arranged so that debris must double back against high-speed airflow leaving the shredding blade before exiting the unit. The shredding blade can be mounted in front of and on the same shaft as an air impeller, with the back surface of the shredding blade being supported by the impeller. In another embodiment, the air impeller and the shredding blade are carried in assemblies that are separable from each other and are each separately attachable to a base unit. A detachable power module and a detachable blower are also shown. The power module has a safety switch that disables the power module when it is removed. A power receptacle is shown with a switch that alternately switches power to either the shredder motor or to the power receptacle, but not to both simultaneously.