NOVELTY - Producing biogas from whey-containing wastewater (104), comprises feeding the wastewater to separating means (105), separating low polluted wastewater (102), discharging and feeding high polluted wastewater (100) to receiving tank (106), hydrolyzing, discharging and feeding the wastewater to conditioning means, conditioning, transferring wastewater into anaerobic methane reactor, methanating the wastewater, thus produces methane gas and bio-sludge, extracting methane gas, discharging bio-sludge, and separating pre-purified waste water from bio-sludge, thus produces concentrated bio-sludge.    USE - The method is useful for producing biogas from whey-containing wastewater.    DETAILED DESCRIPTION - Producing biogas from whey-containing wastewater (104), comprises feeding whey-containing wastewater to a separating means (105); separating low polluted whey-containing wastewater (102) with a degree of organic pollution below a predetermined threshold from the separating means; discharging high polluted whey-containing wastewater (100) with a degree of organic pollution above a predetermined threshold from the separating means and feeding the high polluted whey-containing wastewater to a receiving tank (106); hydrolyzing the high polluted whey-containing wastewater in the receiving tank; discharging the high polluted wastewater from the receiving tank and feeding the high polluted wastewater to conditioning means; conditioning the high polluted wastewater by using the conditioning means; transferring the conditioned high polluted wastewater into an anaerobic methane reactor; methanating the high polluted wastewater in the anaerobic methane reactor by using anaerobic microorganisms, thus forms methane gas and bio-sludge; extracting methane gas from the anaerobic methane reactor; discharging the bio-sludge from the methane reactor; separating pre-purified waste water from the bio-sludge, thus produces concentrated bio-sludge; and recycling the concentrated bio-sludge in the anaerobic methane reactor. An INDEPENDENT CLAIM is also included for a device for producing biogas from whey-containing wastewater, comprises: the separating means for receiving whey-containing wastewater; means for separating low polluted whey-containing wastewater with a degree of organic pollution below a predetermined threshold from the separating means; the receiving tank for receiving high polluted whey-containing wastewater with a degree of organic pollution above a predetermined threshold from the separating means; means for hydrolyzing the high polluted waste water in the receiving tank; means for discharging the high polluted wastewater from the receiving tank and means for feeding the high polluted wastewater to conditioning means; the anaerobic methane reactor for receiving the conditioned wastewater, in which methane gas and bio-sludge are formed; means for extracting methane gas from the anaerobic methane reactor; means for discharging the bio-sludge from the methane reactor; a separator for separating pre-purified waste water from the bio-sludge, thus produces concentrated bio-sludge; and means for recycling the concentrated bio-sludge in the anaerobic methane reactor.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic representation of the device for carrying out wastewater treatment.    High polluted whey-containing wastewater (100)    Low polluted whey-containing wastewater (102)    Whey-containing wastewater (104)    Separating means (105)    Receiving tank (106)