Abstract: An arrangement is provided for facilitating aerobic composting of organic material. The arrangement comprises a compost tank having an upper receiving volume, a central aeration and mixing volume, and a lower compost collection receiving volume. Preferably the central volume includes an air circulation arrangement directing air therethrough, and a mixing arrangement to facilitate mixing of organic material received therein. In the preferred embodiment, the lower compost receiving volume includes a substantially horizontal floor and a conveying mechanism, to convey fully or substantially fully composting material across the horizontal floor, toward a section of the tank from which it can be readily removed. A fluid circulation arrangement is provided, to facilitate liquid dispersion and moistening of organic material throughout the compost tank.