NOVELTY - Air is supplied from an active composting phase treatment space to a composting start-up treatment space in order to increase the temperature in the start-up treatment space. Air is then later discharged from the start-up treatment space to an active composting treatment space. Air and dry waste are then discharged from a treatment space in which the waste is dry.    USE - For drying domestic waste.    ADVANTAGE - High calorific waste suitable for incineration can be produced without separation into RDF and OWF.    DETAILED DESCRIPTION - A method for biological drying of waste, in particular domestic waste, by composting the waste in a series of parallel treatment spaces for performing a start-up phase, an active phase or a cooling phase of composting over a certain number of days, comprises the following steps:    (A) supplying air from a treatment space in which the waste is in the active composting phase, to a treatment space in which the waste is in the start-up phase of composting, in order to increase the temperature in the start-up treatment space;    (B) discharging the air after a time from a start-up treatment space to a treatment space in which the waste is in the active composting phase, in order to reduce the odor and level of volatile hydrocarbons in the air; and    (C) discharging the air and dry waste from a treatment space in which the waste is dry.    INDEPENDENT CLAIMS are also included for the following:    (A) Process apparatus for performing this drying method, comprising interconnected waste treatment spaces connected via closing means to shared systems (3, 4) for supplying air to and removing air from these spaces; and    (B) Method for treating waste, in particular domestic waste, in order to increase its calorific value, comprising composting the waste without previously separating into an organic wet fraction (OWF) and refuse-derived fuel (RDF).    DESCRIPTION OF DRAWING(S) - The figure show a cut-away perspective view of the process apparatus and a detailed view of the water conduit.    Start-up conduit (3)    Surplus air conduit (4)    Water conduit (8)    Perforated inner lining (12)    Distributor pipe (18)