## 3 Results
### Testing the Composition of the Exhaust Gas  
Figure 7 shows how the NOx content of the exhaust gas changed with 0%, 2% and 5% concentrations of silver additives and effective microorganisms. For pure fuel at a 0 kW load, the NOx content was 289 ppm. All additives at a concentration of 2% and a load of 0 kW resulted in a decrease in nitrogen oxides, with the largest decrease of more than 10% observed for the effective microorganisms in the form of ceramic tubes. This measurement needs to be checked to see if it is erroneous, as the other results obtained for other concentrations and additives contradict this. For colloidal nanosilver and effective microorganisms, the NOx content has a value of 266 ppm, a decrease of approximately 8%. In contrast, when the silver solution was used, the NOx value dropped to 271 ppm, a decrease of only approximately 6% compared to NOx emissions when burning pure MDO. The 5% concentration of additives also influenced the decrease in NOx emissions compared to the values obtained with MDO combustion. When the silver solution and \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Flash Point** & **Fuel Density** & **Water Content** & **Bacterial Content** & **Fungal Content** \\  & [\({}^{\circ}\)C] & [g/cm\({}^{3}\)] & [\%] & [cfu/1 dm\({}^{3}\)] & [cfu/1 dm\({}^{3}\)] \\ \hline Pure fuel & 60.3 & 0.8239 & 0.0066 & \(1.1\times 10^{6}\) & \(7.3\times 10^{3}\) \\ \hline Fuel with silver solution & 62.2 & 0.8242 & 0.0145 & \textless{}1 \(\times\) 10\({}^{2}\) & \textless{}1 \(\times\) 10\({}^{2}\) \\ \hline Fuel with colloidal nanosilver & 61.6 & 0.8241 & 0.0078 & \textless{}1 \(\times\) 10\({}^{2}\) & \(1.5\times 10^{2}\) \\ \hline Fuel with EM fluid & 60 & 0.8234 & 0.0109 & \textless{}1 \(\times\) 10\({}^{2}\) & \(1.0\times 10^{2}\) \\ \hline Fuel with EM cer & 61.3 & 0.8240 & 0.0113 & \textless{}1 \(\times\) 10\({}^{2}\) & \(1.0\times 10^{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of selected test results of physical, chemical and microbiological parameters for pure fuel and fuel with the additives. Figure 7: NOx content in exhaust gases for three different additive concentrations at a load of 0 kW. colloidal nanosilver were used, the decrease was more than 15% (to a value of approximately 250 ppm). With regard to the liquid effective microorganisms, \(\mathrm{NO_{x}}\) emissions at the higher concentration increased to 278 ppm and were approximately 4% lower compared to diesel without additives. In the case of EM in the ceramic form, the \(\mathrm{NO_{x}}\) concentration was comparable to the value obtained with the 2% additive and was 259 ppm. Figure 8 shows the change in \(\mathrm{NO_{x}}\) content of the exhaust gas at different concentrations of silver additives and effective microorganisms for a 20 kW load. For the clean fuel at a 20 kW load, the \(\mathrm{NO_{x}}\) content was 874 ppm. As with idling, the 2% additive caused a decrease in \(\mathrm{NO_{x}}\) for all additives, but the largest was observed for the silver solution, which was 846 ppm, representing a decrease of 3%. For colloidal nanosilver, the \(\mathrm{NO_{x}}\) content was 851 ppm (a decrease of approximately 2.5%), while the use of effective microorganisms resulted in the \(\mathrm{NO_{x}}\) values dropping to 860 ppm for the liquid form and to 865 ppm for the ceramic form of the effective microorganisms (a decrease of approximately 1.5%). At a 5% additive concentration, there was a further decrease in the \(\mathrm{NO_{x}}\) content of the flue gas for the addition of effective microorganisms--in liquid form to 822 ppm, in ceramic form to 825 ppm and with the silver solution to 830 ppm, while colloidal silver showed a similar effect as it did at a 2% concentration (852 ppm). At this load value, increasing the concentration of effective microorganisms resulted in a decrease in nitrogen oxides with a decreasing trend. The addition of colloidal silver showed an increasing trend.