NOVELTY - A composting apparatus (900) comprises a housing; an upper processing zone in the housing; at least one lower processing zone positioned below the upper processing zone; a barrier separating upper processing zone from lower processing zone so as to prevent particulate material in upper processing zone from passing into lower processing zone; a biodegradable waste inlet above upper processing zone; a finished compost outlet below the lower processing zone; and liquid barrier device (920) for preventing compost leachate from passing from the upper processing zone to lower processing zone.    USE - For composting biodegradable material to form finished compost material suitable for use in agriculture and horticulture (claimed).    ADVANTAGE - The apparatus has discrete, stacked processing zones, and a leachate retention system which prevents pathogen- containing compost leachate from escaping the composting system, and it thus prevents the contamination of ground water and surface water supplies, and further prevents the contamination of finished compost collected in the compost collection zone in the lower portion of the composting apparatus. The composting apparatus minimizes the amount of land required for a large-scale composting system; and facilitates full control of the environmental conditions for optimal rapid decomposition of biodegradable organic waste and to ensure reliable and consistent output of high quality compost. The composting apparatus has processing zones in a vertical arrangement, thus allowing movement from one processing zone to the next under the influence of gravity alone, and also employs gravity and the primary force for directing leachate into a fluid collection system. A system utilizing the apparatus facilitates the processing of large volumes of carbon based materials, such as wood, chips, paper, and the like, as well as pre-sorted biodegradable waste.    DETAILED DESCRIPTION - A composting apparatus (900) comprises a housing including a housing frame and a housing wall; an upper processing zone in the housing; at least one lower processing zone positioned below the first processing zone; a barrier separating the upper processing zone from the second processing zone so as to prevent particulate material in the upper processing zone from passing into the lower processing zone; a biodegradable waste inlet above the upper processing zone; a finished compost outlet below the at least one lower processing zone; and liquid barrier device (920) for preventing compost leachate from passing from the upper processing zone to the lower processing zone. An INDEPENDENT CLAIM is included for composting material involving: (a) providing a vertical composting system having a vertically oriented housing including a wall, an upper processing zone in the housing, at least one lower processing zone positioned below the first processing zone, at least one device separating the upper processing zone from the second processing zone; a waste inlet above the upper processing zone, a finished composte outlet below the lower processing zone, a temperature and moisture control system, and a leachate retention system; (b) introducing a biodegradable material through the waste inlet; (c) processing the biodegradable material in the upper processing zone while maintaining optimum processing conditions of moisture and temperature; (d) capturing and diverting any liquid leachate produced in the upper processing zone with the leachate retention system; (e) moving at least one agitating device below the upper processing zone thereby allowing the processed biodegradable material to pass into the lower processing zone; (f) processing the compostable material in the lower processing zone to form finished compost material suitable for use in agriculture and horticulture; and (g) removing the composted material through an outlet below the lower processing zone.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional rear view of vertical composting apparatus having leachate retention gate in the closed position.    vertical composting apparatus (900)    telescoping slide gate (920)    fully extended (gate closed) configuration (930)    mounting brackets (950)    outermost telescoping member (970)    hydraulic cylinder. (1050)