# Electrospark Method in Galvanic Wastewater Treatment for Heavy Metal Removal
## 3 Results
Addressing these issues requires further research. It should be noted that some differences in performance are still present and relate to the deep purification of galvanic discharge from zinc ions in the region of low concentrations. Next, we investigated the effectiveness of galvanic wastewater purification when changing the scheme of implementation of the fluid flow (longitudinal/transverse). To realize the longitudinal fluid flow, the condition h \(>l\) was observed, i.e., the fluid flow was realized along with the larger size of the metal loading layer. To organize the transverse flow of the liquid, the height of the layer of granules was reduced to comply with the condition h \(\leq l\)/2 (Tables 7 and 8). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Value** & **Zn\({}^{2+}\)** & **Cr\({}^{3+}\) + Cr\({}^{6+}\)** & **Cu\({}^{2+}\)** \\ \hline \(\Delta_{1}\) mg/dm\({}^{3}\)** & 0.24 & 1.27 & 0.05 \\ \(\Delta_{1}\) mg/dm\({}^{3}\) & 0.19 & 1.27 & 0.05 \\ \(\Delta_{1}\)/\(\Delta_{2}\) & 1.25 & 1.00 & 1.00 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Comparison of purification results when changing the pulse frequency. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Discharge Pulses Frequency** & **Zn\({}^{2+}\), mg/dm\({}^{3}\)** & **Cr\({}^{3+}\) + Cr\({}^{6+}\), mg/dm\({}^{3}\)** & **Cu\({}^{2+}\), mg/dm\({}^{3}\)** & **pH** & **Color** \\ \hline - & 0.26 & 1.27 & 0.06 & 7.45 & light yellow \\ 1\(\times\) & 0 & 0.0002 & 0.007 & 8.00 & colorless \\ 2\(\times\) & 0 & 0.0070 & 0.007 & 8.14 & colorless \\ \hline \hline \end{tabular}
\end{table} 
Table 5: The effectiveness of galvanic purification on changing the discharge pulse frequency. Analysis of the results (Tables 7 and 8) shows that the length of the liquid path through an active layer (the layer where the discharge plasma is formed between the granules and the processes phase transitions of the granule material occur) may be important (in this case, the length is h). That is, the presence of micro- and submicron-powder coagulants in the liquid is not the only purification mechanism. This circumstance is especially related to the processes of zinc and copper ions. The conclusion about technological implementation is obvious. Increasing the height of the layer of granules arbitrarily is not possible. In the lower layers of granules, under the action of weight loading, spark channels cease to be formed, the welding of granules occurs more often, and energy losses increase. It is necessary to divide one reactor into several sections located one above the other. This is possible through the use of dielectric perforated jumpers mounted horizontally. In each section, the maximum possible height of a layer of granules has been provided. The influence of the energy in a pulse on the degree of galvanic wastewater purification at a fixed specific energy (W = 130 kJ/dm\({}^{3}\)) and a slight change in the pulse duration (from 38 to 40 \(\upmu\)s) is presented in Table 9.  
As can be seen from Table 9, the increase in energy in the pulse only leads to deterioration in the purification of metal ions in the low concentration area. Since a multiple increase in the capacity of the capacitor bank leads to such problems, the increase in energy in the pulse in this way is impractical for solving the problems of galvanic purification.