(EP523009-A3)      The plant to convert waste into a compost has a number of troughs in a hall which are open at the top and at least at the rear, sepd. by dividing walls. At least one trolley to mix and feed the waste material delivers it to the leading end of the trough, moving in a zone between the leading end wall of the hall across the troughs and vertically over the leading section of a trough. A transfer trolley moves in a zone between the trailing end of the troughs and the rear end wall of the hall, across the troughs. It has a holder for mixing and delivery trolley and a mechanism to hold the prepared compost and deliver it downwards.    USE/ADVANTAGE -   The assembly is for the conversion of vegetable matter into compost, including domestic waste. The use of trolleys with dual functions reduces the space needed, cutting the length of the leading end of the compost field from 20 m to about 4 m, and the trailing end from 6 m to about 3.5 m    (EP523009-B1)      Composting installation, comprising a composting field in a hall, which field is divided by lengthwise separation walls into a plurality of bays which are open on the topside and at least at the backside, at least one agitating and conveying, carriage being provided which is movable horizontally on two adjacent separation walls from the front bay end, destined to receive compostable matter, to the rear bay end serving for the delivery of the compost, and vice versa, and being equipped for a transfer to other bays, characterised by a mixing and supply carriage (26; 126) for receiving fresh composting matter and for discharging same into the beginning (12A) of the bay, the carriage (26; 126) being movable in a space (42) between the front end wall of the hall (10) transversely to the bays (15) and furthermore perpendicularly thereto on the front region of a bay, and by a transfer carriage (58; 158) being movable within a space (62) between the end (12B) of the bays and the rear end wall of the hall transversely to the bays (15) and being equipped with means (68) for receiving the agitating and conveying carriage (18) and with means (56; 156) for receiving the finished compost and conveying it downwards.