The article discusses the engineering calculation methodology for developing the design of a mobile bioreactor for processing organic waste. The calculations for processing organic waste were based on SNiP, instructions and methods of leading scientists. When calculating the mobile bioreactor, we took into account: the limit of decomposition of fats, proteins, carbohydrates and the formation of biogas with the density of the mixture. A diagram of the phase process of ongoing and sequential decomposition with the maximum possibility of fermentation for an organic mixture with activated sludge over time, under aerobic and anaerobic conditions during waste disposal, is presented. The advantages and disadvantages of dry and wet waste processing methods are analyzed. From the calculations obtained, we can draw the following conclusion: in a bioreactor with a volume of 7.5 liters, in thermophilic mode, and with a volume of 15 liters, in mesophilic mode, approximately 50% of the organic mixture is fermented, and with activated sludge with a wet substrate, about 95%.