## 4 Conclusions  
The research focused on the analysis of stabilized sewage sludge for the presence of MPs. The statistical analysis was related to months. The tested samples contained huge amounts of plastic microparticles, and their highest content was recorded in June, July, and May, respectively. The MPs content in the stabilized sewage sludge from May amounted to an average of 1745 fragments and was the smallest in relation to the rest of the tested samples. The microplastic content in June averaged 2942 fragments, and samples from this period displayed the highest number of MPs. On the contrary, the July samples showed an average of 2340 microplastic fractions per 100 g of dry matter. The researchers noticed the effect of the number of MPs as a function of weather conditions. A greater number of plastics was recorded at higher temperatures. In each of the samples, fragments dominated, especially black ones, by about 44%. Colored pieces were the second most abundant. The most common polymer in the stabilized sewage sludge was low-density polyethylene (LDPE). The most likely sources of these substances are plastic bags, bottles, nets, and drinking straws. The highest number of fractions above 300 \(\upmu\)m were found in samples from June and July and the lowest in May; the highest number of fractions below 300 \(\upmu\)m were found in samples from May, followed by June and July. This may be due to the presence of plastics under conditions that have a greater impact on their degradation, such as temperature changes. SEM images showed that the type of the separated microplastics varies, from smooth with defects and crevices to highly porous. In each case, there is a potential for the sorption of various types of pollutants, including heavy metals, pharmaceuticals, and pesticides. Studies have confirmed the risk of re-emission of MPs into the environment by stabilized sewage sludge and fertilizers produced from it. Converting the masses of the samples to 100 g of dry mass allows the number of plastic microfractions to be compared with each other. Attention should be paid, for example, to the most harmful fractions, which are characterized by the smallest size and negligible weight. The quantitative content of MPs should be a necessary precedent used in estimating the amount of this type of contamination and is used by many scientists dealing with this problem. From the research, it can be concluded that the use of sewage sludge to obtain organic mineral fertilizers enables their re-emission into the environment. Future research, which is in progress, focuses on the analysis of organic mineral fertilizers based on stabilized sewage sludge. In this study, the authors analyzed the occurrence of microplastics (MPs) in stabilized sewage sludge from a specific wastewater treatment plant (WWTP), providing specific data that contribute to the understanding of MPs in the context of sewage sludge used for fertilizer production. Although issues related to MPs in wastewater treatment processes are documented, a novel aspect of this study is the detailed quantification of MPs in the specific wastewater treatment plant under consideration, as well as the identification of the dominant polymer types and morphological forms present. In addition, the study also focuses on the potential environmental risk posed by polymers, given their role as pollutant vectors, which has been less emphasized in previous work. Research on the presence of MPs in fertilizers and their potential impact on the environment has been combined. This paper makes a timely and important contribution to the growing body of research on microplastics in agricultural systems. The findings not only increase existing knowledge, but also provide new insights into the transport and re-emission of MPs into the environment, highlighting important issues such as the need to monitor and regulate MPs in agricultural products obtained from wastewater treatment. Conceptualization, J.W. and K.S. ; methodology, J.W., J.C., K.B. and K.S. ; formal analysis, J.W. and K.S.