A Method and Device for solidification of waste liquids and fluids is disclosed. The invention is particularly well suited to processing radioactive waste fluids; and employs a metered polymer supply assembly and metered waste supply assembly, which have a prescribed positional orientation in relation to themselves and a container. These assemblies operate in relation to each other to meter, mix and position a solidification agent or polymer with a waste fluid so that a dirt-like polymerized waste product is produced and positioned in the container for safe shipment or storage. The waste supply assembly in a preferred embodiment is provided with a novel waste trough. Prescribed mathematical relationships for determining the trough length, and the cross-sectional dimensional relationship of the polymer chute of the invention in relation to the cross-sectional dimensional magnitude of the waste trough is set forth.