Abstract: A process and apparatus is disclosed for the biological treatment, in particular composting, of biogenic and abiogenic substances and/or mixtures of substances in a compost pile in the presence of biologically active components such as microorganisms. The process occurs in a closed reactor having a plurality of reactor zones, namely the compost pile itself and at least one reactor gas space adjacent to the compost pile. Rotting conditions, changes in rotting conditions and/or process parameters in the compost pile are adjusted, maintained, controlled or regulated, steady-state, quasi-steady-state and/or non-steady-state operation of the reactor.

Abstract: A composting unit is disclosed having a ventilation system for closed rotting units. A number of fans, passageways, and valves are designed and arranged in such a way that they ensure flow of conditioned circulating air, as desired, over and/or through and/or around a static or agitated stack of composting material.