## 3 Results
### Testing of Hourly Fuel Consumption
The highest consumption was observed for the liquid effective microorganisms, which amounted to 13.9 dm\({}^{3}\)/h. A slightly lower consumption occurred after the use of colloidal nanosilver, which reached 13.8 dm\({}^{3}\)/h. Effective microorganisms in the form of ceramic tubes at higher concentrations resulted in an increase in the consumption of 0.2 dm\({}^{3}\)/h compared to pure diesel. The lowest increase in fuel consumption occurred with the silver solution to 13.4 dm\({}^{3}\)/h. Again, the most beneficial additive was the silver solution applied at a 2% concentration, after which the fuel consumption decreased by approximately 2.5%. The development of internal combustion engines is largely determined by the increasingly stringent emission standards being introduced. Meeting the high requirements of these standards creates the need to optimise both the process of fuel combustion in the cylinder and to improve non-engine ways of reducing exhaust emissions. An equally important factor of particular importance to users is fuel consumption, the impact of which on operating costs is significant. The amount of fuel consumed, in turn, is directly related to CO\({}_{2}\) emissions, which are subject to significant restrictions in EU directives. These include such measures as the addition of catalyst-based additives to fuels, the use of fuel-water emulsion injection or the injection of water into the engine. The additives introduced into the test fuel consisted mainly of water (except for effective microorganisms in the form of ceramic tubes), so the fuel delivered to the cylinder was a fuel-water emulsion. Water supplied to the cylinder of an internal combustion engine can have a reducing and inhibiting effect on the processes of formation of harmful substances in the combustion chamber, especially during the first stage of fuel combustion. This is because during this period, dehydrogenation of the fuel takes place, along with the accompanying processes of pyrolysis. The result of these processes is the formation of mainly particulate matter. Elements inhibiting the formation of soot particles are free OH radicals formed with the participation of oxygen. Their two renewal is intensified by such factors as the oxygen content, temperature and pressure in the combustion chamber. The reactions of OH radical formation can be written as follows [52; 53]:  
\[\mathrm{H_{2}O}\rightarrow\mathrm{OH+H} \tag{1}\]  
\[\mathrm{H_{2}O+O\rightarrow\mathrm{OH+OH}} \tag{2}\]  
\[\mathrm{H_{2}O+H\rightarrow\mathrm{OH+H_{2}}} \tag{3}\]  
As can be seen, the presence of water in the combustion chamber can significantly affect the number of OH radicals. In the case of a ZS engine, in the first phase of mixing of fuel particles with air at a high temperature and pressure, CC and C-H bonds are broken. As a result of such processes, among other things, carbon-rich residues are formed, the rapid afterburning of which requires the presence of oxygen and a catalyst. A certain type of catalyst for these reactions can be steam, which, being above the critical parameters (374 \({}^{\circ}\)C and 221 bar) significantly increases its catalytic capacity [54]. Thus, supplying water to the cylinder accelerates carbon afterburning, but at the same time, due to the cooling properties of water, it lowers the maximum combustion temperature and thus leads to a reduction in nitrogen oxide emissions, the formation of which in the case of poor mixtures (compression-ignition engine) is largely dependent on the temperature prevailing in the combustion area. As can be seen from the analysis of the data in Table 4, the highest amount of water in the fuel was observed precisely in the fuel doped with ionic silver, so the best results were obtained for this mixture. In addition, the fuel was also subjected to microbiological tests, from which it can be observed that the smallest amount of bacteria and fungi was obtained for the ionic silver additive. The problem of microbiological contamination is most common in tanks with longer storage periods.