Features of two new machines introduced by Pennwalt Ltd in Great Britain to its range of sewage sludge dewatering centrifuges: the Sharples Sludgepak, a vertical-axis basket-type, solid-bowl machine designed for the more difficult slimy sludges such as waste activated and highly flocculated alum sludges; and the Sharples, Nozljector, a high-capacity disk centrifuge for thickening waste activated sludge from plants producing in excess of 70 m**3/hr.