For disposing of liquid pig manure by composting same with solid carbonaceous matter. The composting material is contained in a trough, and is turned by means of an apron, which is supported in a carriage for a travelling along the trough. The apron carries moving rakes which lift and turn the material. The apron can be set to traverse both backwards and forwards. The apron is angled to a bottom-leading configuration during traversing, and the apron is capable of being lifted, to change the angle, when setting up for reversing the traverse.
