Animal production is a major source of environmental pollutants, so it is becoming crucial to search for new methods to reduce their release while maintaining animal welfare. The aim of the study was to apply natural additives to rabbit manure in ex situ conditions to reduce the volume of released gaseous pollutants like ammonia (NH₃), methane (CH₄) and hydrogen sulphide (H₂S). The study was carried out in two stages, each with a control group and five experimental groups with additives, natural sorbents (zeolite, bentonite biochar, perlite, mixtures in various proportions of zeolite, biochar and bentonite as well as perlite and biochar) or dried plants containing saponins (Tribulus terrestris and Lysimachia nummularia). Pollutants from each group were measured continuously for one month. In stage 1, both in the case of NH₃ and CH₄, statistically significant differences were observed between the tested groups. The use of sorbent mix and Tribulus terrestris was shown to reduce the release of both NH₃ (by 80% and 83%, respectively) and CH₄ (by 17% and 25%, respectively). The greatest reduction of NH3 in stage 2 was achieved when perlite with the addition of biochar was used (56%), and CH₄ was achieved when Bacillus azotofixans sp. nov. bacteria were used (38%).

Biogas plants processing municipal waste are very important investments from the point of view of waste management and also the sustainable development of urban infrastructures. They may also have a potentially negative impact on the environment in the form of odour emission. Olfactometry is the main method for odour impact assessment. Field olfactometry allows for performing a wide range of tests, the results of which are practically instantaneous. The purpose of this work is to provide a tool for assessing the odour impacts of municipal management facilities, including biogas plants processing municipal waste and evaluating the correctness of processes carried out in these plants, namely the method of field olfactometry. In order to compare obtained olfactometric results with the concentration of chemical compounds, chromatographic tests were also carried out using the Photovac Voyager portable chromatograph (hydrogen sulphide – H2S and dimethyl sulphide – (CH3)2S. The results of the odour concentration tests are in line with the results of odorant concentration tests and indicate that cod is strongly related to the concentration of hydrogen sulphide. Thanks to this method, it is possible to find a relationship between odour nuisance, technological processes used in the plant and the type of treated waste.