# Electrospark Method in Galvanic Wastewater Treatment for Heavy Metal Removal
## 3 Results
So, the discharge duration is increased from 38 to 200 \(\upmu\)s.  
The effectiveness of galvanic purification when changing the pulse processing parameters is given in Table 4. As can be seen from the data on the concentrations of heavy metal ions after treatment (Table 4), changes in the efficiency of purification with a significant change in the pulse parameters did not occur. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Discharge Duration \(\uptau_{\text{L}}\), \(\upmu\)s** & **Zn\({}^{\text{2+}}\), mg/dm\({}^{3}\)** & **Cr\({}^{\text{3+}}\) + Cr\({}^{\text{6+}}\), mg/dm\({}^{3}\)** & **Cu\({}^{\text{2+}}\), mg/dm\({}^{3}\)** & **pH** & **Color** \\ \hline - & 0.26 & 1.27 & 0.06 & 7.45 & light yellow \\
38 & 0 & 0.0002 & 0.003 & 7.34 & colorless \\
200 & 0 & 0.0002 & 0.003 & 7.33 & colorless \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The efficiency of galvanic purification in the process of changing the duration of pulse discharge. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Specific Energy, kJ/dm\({}^{3}\)** & **Zn\({}^{\text{2+}}\), mg/dm\({}^{3}\)** & **Cr\({}^{\text{3+}}\) + Cr\({}^{\text{6+}}\), mg/dm\({}^{3}\)** & **Cu\({}^{\text{2+}}\), mg/dm\({}^{3}\)** & **pH** & **Color** \\ \hline - & 0.26 & 1.27 & 0.06 & 7.45 & light yellow \\
130 & 0 & 0.0002 & 0.003 & 7.34 & colorless \\
65 & 0.028 & 0.0023 & 0.010 & 8.19 & colorless \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The efficiency of galvanic purification in the process of changing the specific energy. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Value** & **Zn\({}^{\text{2+}}\)** & **Cr\({}^{\text{3+}}\) + Cr\({}^{\text{6+}}\)** & **Cu\({}^{\text{2+}}\)** \\ \hline \(\Delta_{1}\)**mg/dm\({}^{3}\)** & 0.26 & 1.27 & 0.06 \\ \(\Delta_{1}\)**mg/dm\({}^{3}\)** & 0.23 & 1.27 & 0.05 \\ \(\Delta_{1}\)/\(\Delta_{2}\) & 1.12 & 1.00 & 1.14 \\ Kr\({}_{1}\) & - & 6350 & 20 \\ Kr\({}_{2}\) & 9.29 & 552 & 6 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of purification results with changing the specific processing energy. This conclusion has practical value. The change in the pulse parameters of the treatment due to the increase in inductance has almost no effect on the purification efficiency. There is a possibility of a serial (in the electrical sense) connection of several purification reactors to one source of discharge current pulses without any loss of purification efficiency. The \"softening\" of the working conditions of the electric equipment can promote an increase of its resource, reducing the intensity and regulation of the frequency spectrum of electromagnetic interference, etc. Note that by visual signs, the change in the temperature of the discharge plasma between the granules occurred (the color temperature changed). This aspect requires further research using high-speed photo recording and may be useful in determining priority mechanisms for electro spark cleaning. The effectiveness of processing when changing the frequency of discharge pulses was studied by fixing the volumetric speed of the fluid flow. To solve this problem, two galvanic treatments were performed. The volumetric flow rate of the liquid was recorded at 50 dm\({}^{3}\) h. Two frequencies of discharge pulses were established, which were correlated as 1/2. The first frequency is the same at which the results described above are obtained. The specific processing energy was chosen between two values of 130 and 65 kJ/dm\({}^{3}\) (namely, 90 kJ/dm\({}^{3}\)) and was also recorded. The energy released in the interelectrode gap of the reactor during one discharge pulse and the stored energy remained unchanged: W\({}_{\text{P}}\) = 3.6 J and W\({}_{0}\) = 4.5 J (Tables 5 and 6). The results of the experiments (Tables 5 and 6) indicate the possibility of increasing the productivity of galvanic discharge cleaning by the electrospray method by increasing the discharge pulse frequency. Such an increase is possible up to certain limit values and has certain limitations on the initial concentrations of the pollutant.