An electrical type grid electrostatic collector/separator removes particles from an air stream. The apparatus includes multiple parallel grids that act as the porous material, enclosed in a sealed compartment so that the entrained air flows parallel and between one or more centrally located grids. A direct current high voltage field is established between the grids with the polarities alternating between facing grids. Finer particles may be temporally collected on plate or grid assemblies that are located out of the airflow. When non-conductive particles are present, external methods of pre-charging by corona discharge are preferably used. When non-conductive particles are present, both internal and external methods of pre-charging by corona discharge are used with the external method being preferred.