NOVELTY - Apparatus for producing fuel from waste sludge comprises a fermenter in the form of a steel vessel, four horizontal screws, with cutting blades arranged in two planes, an aeration system comprising an air pipe and a fan, a side discharge device, a cover, with an integral air purification system, a spray head, for delivering a microbial suspension, a drive unit, and a control system comprising temperature and oxygen sensors.    USE - The apparatus and method are used for producing fuel from waste sludge.    ADVANTAGE - A high-grade low-emission fuel is produced and organic pollutants, e.g. polychlorinated biphenyls, organically bound halogens and polycyclic aromatic hydrocarbons, are degraded.    DETAILED DESCRIPTION - Apparatus for producing fuel from waste sludge comprising:    (a) a fermenter (4) in the form of a steel vessel that tapers conically below and has a rectangular base and is provided with a supporting structure;    (b) four horizontal screws (1, 2) with cutting blades arranged in two planes;    (c) an aeration system (3) comprising an air pipe and a fan;    (d) a side discharge device (8);    (e) a cover (6) with an integral emission control system (7);    (f) a spray head (5) for delivering a microbial suspension;    (g) a drive unit; and    (h) a control system comprising temperature and oxygen sensors.    An INDEPENDENT CLAIM is also included for producing fuel from waste sludge using the apparatus,comprising:    (a) comminuting a renewable cellulosic material in the fermenter and mixing it with waste sludge to give a mixture with a solids content of 50-55% and a pH of 7.0-8.5;    (b) adding a starter in the form of a prefermented mixture of waste sludge and renewable cellulosic material; and    (c) fermenting the mixture for 48-72 hours.    DESCRIPTION OF DRAWING(S) - The drawing shows apparatus for producing fuel from waste sludge as above.    Screws (1, 2)    Aeration system (3)    Fermenter (4)    Spray head (5)    Cover (6)    Emission control system (7)    Discharge device. (8)