Abstract: A filter system for removing organic, odor-causing substances from air has a filter bed which includes porous, particulate, non-compostable material and microorganisms capable of digesting the odor-causing substances. The particulate material of the bed is preferably lava rock, pumice or sandstone. A method of filtering air which contains organic, odor-causing substances, such as exhaust air from a process of thermophilic bacterial digestion of organic waste matter, includes providing a filter bed of particulate, porous, non-compostable material, inoculating the filter bed with a culture of microorganisms and passing the air through the filter bed.

Abstract: A rotatable apparatus for introducing and dispersing a fluid, such as gas or liquid, in a liquid has outwardly and rearwardly projecting blades about it periphery and air exit ports immediately rearward of said blades. In one embodiment, the apparatus is an aerator having an upper body, a lower body and replaceable blades affixed between the upper and lower bodies. The blades have a body portion positioned between the upper and lower bodies and a projecting portion extending radially outwards. The upper body has an axial bore which is connected to a rotatable hollow tube open to the atmosphere. As the aerator is rotated by rotation of the tube, air is drawn through the tube into the body of the aerator and is ejected through air exit ports between the blades into the liquid. In another embodiment, the aerator has a plurality of radially extending tubes with air exit ports and radially extending blades proximate their outer ends.

Abstract: An aerator for introducing and dispersing air as fine bubbles in a liquid-solid slurry has a lower body, an upper body and replaceable blades affixed between the upper and lower bodies. The blades have a body portion positioned between the upper and lower bodies and a projecting portion extending radially outwards. The upper body has a vertical axial bore which is connected to an air tube open to the atmosphere. As the aerator is rotated by rotation of the air tube, air is drawn through the air tube into the body of the aerator and is dispersed out through air exit ports between the blades into the slurry, without intake of slurry into the aerator.