Abstract: The invention relates to a method and apparatus for the reduction in the quantity of low activity organic wastes from nuclear power plants. This is accomplished using anaerobic fermentation in a bioreactor. The waste from the nuclear power plant is subjected to a pretreatment such as comminution and suspension, hydrolysis and/or physical dispersion, such as by a irradiation, heat treatment or the equivalent. The pretreated waste is subjected to anaerobic decomposition in a bioreactor, the anaerobic decomposition taking place in two stages, namely an acid stage and a methane stage. The gases produced in the decomposition process are conducted from the methane stage to a gas burning stage and the undecomposed waste is removed, concentrated and packed in barrels or the like for storage.

Abstract: The invention relates to a device for treatment of wastewater by means of an anaerobic fermentation, which comprises a closed tank 1 and therein elements 2, 10 for feeding wastewater to be treated into the tank, elements 5, 6 3 for removing treated water, gas and sludge from the tank, elements 4 for mixing the contents of the tank and elements 7 for separating gas in the upper part of the tank. Deviating from the traditional completely mixed reactors the tank has been devided into two, on each other placed parts by means of the filters, which tank comprises a filter media bed containing at least one filter media which acts as an attachment bed for methane bacteria and on it a sludge and fluidized material bed, whereat the mixing elements 4 are below the filter and the feed elements 2, 10 for wastewater to be treated are fed below the filter 8 and the elements 5, 6 for removing treated water and gas are located in the tank part above the filter 8.