Domestic sewage from unsewered scattered areas presents high environmental risk. Due to the high cost of transporting sewage to the municipal sewage treatment plants, the households try to solve the problem in another way, which is very often dangerous to the nature. Polish legislation authorizes the use of domestic sewage as an organic fertilizer in agriculture, once the proper parameters, mainly sanitary ones, have been reached. The main hazards in sewage include Salmonella bacteria and the eggs of intestinal parasites. That is why in the Institute of Biosystems Engineering at the University of Life Science in Poznań research works are carried out on biological inactivation of domestic sewage by means of exhaust gases from the diesel engine. Liquid or semi-liquid substances of animal origin may also be treated in a similar way. In order to carry out laboratory-scale studies, the project was developed along with the test model for domestic sewage inactivation, and then a full research station was created.