Abstract: A relatively thin briquetting chamber having a filter screen along at least one wall thereof, openable ends, a piston movable through said chamber from one end to the other to squeeze liquid from solid particles collected on the screen in said chamber and form a briquette, and an opening in the chamber for introducing the liquid and solid particles into the chamber. The chamber is so designed that no point inside the chamber is more than about three inches from a filter screen wall. This chamber may comprise a flat rectangular parallelepiped having openable ends, a bottom screen wall, a pair of side walls along the longitudinal edges of the bottom wall, and a top wall having an opening therein for introducing the liquid and solid particles, which if in the form of a sludge, this opening has to have a minimum dimension of at least six inches.