Abstract: A collapsible biodegradable container, or bag, for containing liquid-containing solid materials, e.g., compostible materials, such as food waste, yard waste, etc., from restaurants, homes, etc. A single sheet of two-ply material is used to form both the bag side walls, as well as the bag bottom wall. Kraft paper is used to form the bag outer surface, whereas a cellulose film, or cellophane, is used to form the bag inner surface. A slab of moisture-absorbent material is also placed on the bag bottom wall, to intercept liquid draining from the contained material toward the bag bottom wall. The outer paper ply gives the bag its structural strength, so that it can be self-sustaining in an upright condition. The inner cellulose layer, or cellophane ply, provides a liquid barrier to protect the outer paper ply from the destructive effects of liquid. The bag, is also permeable to air and water vapor, while retaining liquids.