The use of alternative fuels and fuel components derived from organic and inorganic waste enables progress toward the goals set by decarbonization policies and environmental protection, but on the other hand, it presents a number of challenges related to maintaining the operational quality of these fuels. This primarily involves achieving normative physico-chemical parameters for newly formulated blends intended for powering automotive engines, as well as identifying and effectively removing both solid and liquid contaminants specific to each fraction (component). Information concerning the chemical composition and purity of individual fuel components is essential in the context of formulating substitute fuels. This article presents the results of comparative studies on the amount of contaminants found in substitute fuel components such as hydrotreated vegetable oil (HVO), tire pyrolysis oil (TPO), and plastic-derived pyrolysis oils – polypropylene pyrolytic oil (PPO) and polystyrene oil (PSO). For diesel fuel and substitute fuels, microfiltration was carried out using membrane filters to determine the quantity of solid impurities. The aim of the study was to assess the feasibility of using these types of fuels either on their own or in blends with diesel fuel, under the assumption that they would be used directly after processing to power compression ignition engines. The research showed that the distillation process of pyrolytic oils significantly reduces the content of process-related impurities. The greatest reduction was observed for PPO, where after filtering a 50 ml sample the level of contaminants after distillation and ashing decreased from approximately 23 mg to a value close to zero.