Abstract: A method for reducing the amount of wastewater treatment station sludge first performs wastewater purification with fixed biological cultures from which excess sludge is extracted intermittently during phases of washing and unclogging. Then, the water from the washing phase that provides fixed biological cultures is subjected to biological activated sludge treatment, the outlet of this stage does not recycle effluent to the front end of the water treatment line. The wastewater is then subjected to a stage of reduced sludge production (RPB), selectively, by thermophilic enzymatic action or by partial oxidation by ozone introduced by mechanical stirring, this stage being supplied by quantities of sludge from the step of biological treatment by activate sludge, the substrate source for the bacteria of the biological treatment including organic material derived from lysed bacterial cells induced during the RSP stage.

Abstract: The invention concerns a method for reducing production of urban or industrial waste water treatment station sludge with fixed biological cultures. The invention is characterized in that it consists in: dissociating the step of reducing sludge production from the purifying step, by providing a step of activated sludge type biological treatment with low, medium or high load, associated with a sludge production reducing step by thermophilic enzymatic process, or by partial ozone oxidation combined, with mechanical stirring, the substrate source for the biological treatment bacteria consisting of the organic matter derived from lyzed bacterial cells induced during the sludge production reducing step.