## 3 Results
### The Effect of UP and PEF on BMP
The BMP from landfill leachate increased significantly by 44% at the highest intensity. The pretreatment results using a pulsed electric field of fruit/vegetables demonstrated that 15 kWh/m\({}^{3}\) is an intensity at which the highest BMP was achieved. Above this intensity, BMP decreased. [PERSON] et al. [36] subjected grass from the _Pemnisteum_ family to pretreatment under different conditions of a high-voltage pulsed electric field (HPEF) in order to improve the material utilisation and BMP coefficients in the anaerobic digestion process. In the study, they demonstrated that, compared to the control group, nine _Pemnisteum_ groups subjected to HPEF pretreatment exhibited higher biogas production and a higher methane concentration than that of control samples. The best results were obtained under the HPEF conditions of 15 kV/120 Hz/60 min, as in this variant, the cumulative gas production over the period was 9587 mL, with the obtained amount being greater by 26.95% than that in the control group. [PERSON] et al. [37] analysed pretreatment in the PEF technology to improve biogas production from ley crop silage. The BMP increased by 16% with the digestion time shorter by 30% compared to the substrate subjected to no pretreatment, using an electrical voltage \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Series**} & \multicolumn{2}{c}{**UP**} & \multicolumn{2}{c}{**PEF**} \\ \cline{2-5}  & **k** & **r** & **k** & **r** \\ \hline
0 & 0.13 & 28.57 & 0.20 & 41.26 \\
1 & 0.18 & 38.20 & 0.24 & 49.64 \\
2 & 0.21 & 47.35 & 0.24 & 51.62 \\
3 & 0.20 & 47.32 & 0.23 & 53.99 \\
4 & 0.15 & 36.15 & 0.24 & 57.58 \\
5 & 0.14 & 34.10 & 0.21 & 51.65 \\
6 & 0.11 & 28.46 & 0.29 & 69.24 \\
7 & 0.23 & 55.85 & 0.29 & 69.85 \\
8 & 0.14 & 35.84 & 0.43 & 103.34 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Kinetic parameters. Figure 5: BMP from a substrate pretreated with PEF, along with the kinetic parameters of the first-order model. of 96 kV/cm. According to [PERSON] et al. [38], the PEF pretreatment of the crop remains increases the biogas production and BMP efficiency by 18% and 16%, respectively, in maize stalks, and by 18% and 17%, respectively, in soybean straw. [PERSON] et al. studied the effect of various types of pretreatment, including US I PEF treatment, on methane production from grape pomace. The PEF system consisted of a high-voltage power supply and a pulse generator; pulse duration (10-5-10-4 s) and frequency (24-240 Hz) were adjustable. The highest recorded increase in methane production after PEF was 4%, compared to methane obtained from untreated substrate. Ultrasonic treatment involved the use of an ultrasonic processor with an operating frequency of 50 kHz and an effective output power of 60 W; the use of Us treatment resulted in a 10% [32]. The authors in an earlier study compared the effect of PEF on the increase in BMP efficiency from corn silage. They noted then an increase in the amount of carbohydrates in the dissolved fraction which resulted in an increase in BMP. The highest amount of methane was obtained after using PEF for 180 s; there was then a 14% increase in production. The BMP for the control sample was 401.83 mL CH\({}_{4}\)/g VS, and for the sample after PEF was 465.62 mL CH\({}_{4}\)/g VS [23]. The determination of BMP allowed the energy balance (Table 3). To determine the energy input (E\({}_{\text{in}}\) (Wh/gTS)) determining the energy expenditure for the disintegration process, the actual energy consumption of the PEF voltage generator and ultrasonic disintegrator was measured. The amount of energy input determines the energy intensity of the substrate pretreatment process. E\({}_{\text{out}}\) is the energy gained due to the increase in BMP caused by pretreatment, considering methane's energy value.