Among sewage generated in wastewater treatment plants, dairy sewage sludge is the most suitable for environmental and farming application. Due to its physio-chemical content, it should be treated as raw material, not waste. Moreover, dairy sewage sludge is characterized by low heavy metals content and high fertilizing value; it is a source of not only coal, but also nitrogen and phosphorous. Their safe usage without pretreatment in the environment is becoming more and more problematic in view of legal regulations which limit, and in the future perspective prevent, a direct application of untreated sewage sludge as fertilizer. The present paper was aimed to determine the influence of particular methods and biological processes, including the application of Effective Microorganisms, on the change in characteristics of treated dairy sewage sludge, especially when discussing changes in the content of nutrients and macroelements. The purpose of the conducted research was to specify the possibility of using natural biological methods of dairy sewage sludge treatment and adapting it to environmental, especially farming use. Excess sludge from biological dairy sewage treatment, which was aerobically stabilized in separate chambers, was used in the research. In all of the facilities where sludge was treated with biological methods, The conducted research was comprehensive and the obtained experiment results point to the necessity of continuation and further development of research concerning content transformation in dairy sewage sludge during its biological treatment. Establishing the role of microorganisms present in the EM formula on the processes and transformations occurring in biologically treated sewage seems to be of exceptional importance. The innovativeness of the research lay mainly in a very comprehensive range of natural biological methods of treatment applied for the same sewage sludge coming from dairy wastewater treatment plants. The conducted research points to the influence of the EM formula on vital changes in the content of macroelements in biologically treated dairy sewage sludge. The most important impact (from the point of view of the number of parameters and the change in size as a result of applying EM formula) was observed in reference to vermicomposting process with the use of earthworms and long-term stabilization in reed beds.