NOVELTY - The method comprises extracting clear water from a multi-modular unit, collecting heat and producing high-quality water in a joint and simultaneous manner, producing an energy by a reactor (35) heated by the heat recovered by a heat pump (32), and ensuring multi-line objectives of the multi-modular unit. The reactor comprises methanogenic microorganisms. The energy producing step is an anaerobic step, produces the energy in thermal and/or electric form by coupling the reactor with cogeneration of a mini power station (39), and produces the energy in a form of a fluid under pressure.    USE - The method is useful for treating and purifying waste water such as industrial waste water and domestic waste water, to produce high-quality water by recovering thermal energy and chemical energy (all claimed) in an urban environment.    ADVANTAGE - The method is capable of efficiently treating and purifying the waste water without the emissions of carbon dioxide thus producing high quality water.    DETAILED DESCRIPTION - The method comprises extracting clear water from a multi-modular unit, collecting heat and producing high-quality water in a joint and simultaneous manner, producing an energy by a reactor (35) heated by the heat recovered by a heat pump (32), and ensuring multi-line objectives of the multi-modular unit. The reactor comprises methanogenic microorganisms. The energy producing step is an anaerobic step, produces the energy in thermal and/or electric form by coupling the reactor with cogeneration of a mini power station (39), and additionally produces the energy in a form of a fluid under pressure. The cogeneration of the mini power station utilizes methane produced by the reactor. The energy producing step produces a biogas of 30-65% when working on mesophilic and thermophilic temperatures ranges during an usage of a domestic waste water, and produces a biogas yield of 50-95% when working on the mesophilic and thermophilic temperatures ranges during an usage of an industrial waste water. The multi-line objectives from the extracting step to the energy producing step jointly and simultaneously comprise hydraulic, energy and behavior optimization of the objectives of treatment. An INDEPENDENT CLAIM is included for a multi-modular device for waste water treatment and purification.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a multi-modular device for waste water treatment and purification.    Heat exchangers (31)    Heat pump (32)    Reactor control unit (34)    Reactor (35)    Mini power station. (39)