NOVELTY - A sludge treating equipment for treating sludge created by an aerobic waste treatment plant comprises mechanism that causes the sludge to flow through a treatment duct. The treatment duct comprises a cylindrical pipe with a multiplicity of ultrasonic transducers attached to the outside of the pipe, and an anaerobic digester comprising an outlet for biogas and energy conversion mechanism for obtaining energy from the biogas.    USE - For treating sludge created by an aerobic waste treatment plant (claimed), useful in, e.g. food processing plants.    ADVANTAGE - The inventive equipment uses ultrasonic treatment to breakdown the cell walls and membranes within the sludge, so that the compounds within the cell walls and the cell contents are released into the water, increasing the proportion of the organic substances that can be readily be biodegraded, increasing the biogas production from the biodigester and reducing the quantity of residual solid matter that remains in suspension.    DETAILED DESCRIPTION - A sludge treating equipment for treating sludge created by an aerobic waste treatment plant comprises a mechanism to cause the sludge to flow through a treatment duct (40). The treatment duct comprises a cylindrical pipe with a multiplicity of ultrasonic transducers (42) attached to the outside of the pipe in an array of separate transducers that extends both circumferentially and longitudinally; and an anaerobic digester (34) to which sludge that has passed through the treatment duct is supplied. Each transducer is connected to a signal generator so that the transducer radiates less than or equal to3 W/cm2. The anaerobic digester has an outlet for biogas, and energy conversion mechanism for obtaining energy from the biogas.    DESCRIPTION OF DRAWING(S) - The figure shows an aerobic treatment unit that processes aqueous waste generated from a food processing factory before discharging it into a public waste water system.    Holding tank (24)    Pump (26)    Anaerobic digester (34)    Treatment duct (40)    Ultrasonic transducers (42)