## 2 Materials and Methods
### Analytical Methods and Process Evaluation  
(a) Monitoring of Physico-Chemical Parameters  
The efficiency of the Al-based ECZ and ECZ-MAG processes was evaluated by monitoring key physico-chemical parameters (pH, temperature, chemical oxygen demand--COD, turbidity, total solids--TS). Temperature and pH were measured during treatment in defined time intervals, while other parameters were measured before and after treatment in order to assess the process performance. Temperature was measured using a Testo digital thermometer (Titisee-Neustadt, Germany), while pH was determined with a Mettler Toledo Seven Multi pH meter (Greifensee, Switzerland). Chemical oxygen demand (COD) was analyzed using the standard dichromatic method. Turbidity was measured with a Velp turbidimeter ([PERSON], Italy), and total solids were quantified gravimetrically by drying the samples at 105 \({}^{\circ}\)C. All analyses were performed in accordance with Standard Water and Wastewater Testing [31]. (b) Hybrid Process Efficiency  
The percentage of COD and turbidity decrease was calculated using the following equation:  
\[\text{Decrease~{} percentage~{}(\%)}=\frac{\text{c}_{0}-\text{c}_{\text{f}}}{ \text{c}_{0}} \tag{1}\]  
where c\({}_{0}\) is the initial value (mg/L or NTU), and c\({}_{\text{f}}\) is the final value (mg/L or NTU). (c) Quantifying and Electrode Loss, Faradaic Efficiency, and Energy Input  
The actual mass loss of the aluminum electrodes was determined by gravimetric analysis, based on the difference in the electrode mass before and after the experiment to quantify the amount of aluminum dissolved during the EC process. Prior to the experiment, the masses of both electrodes were measured. Following each experiment, the electrodes were ultrasonically cleaned in deionized water for 10 min, dried in a laboratory oven, and subsequently weighed using an analytical balance. The actual mass loss was calculated using the following expression:  
\[\text{C}_{\text{actual electrode}}=\frac{\text{m}_{\text{actual}}}{\text{V}} \tag{2}\]  
where  
\(\text{m}_{\text{actual}}\)--the experimentally measured electrodes mass loss (g),  
V--the reactor volume (m\({}^{3}\)). \begin{table}
\begin{tabular}{c c c c} \hline
**Exp.** & **Magnetic** & **Mixing Speed, rpm** & **Contact Time, min** \\ \hline ECZ, 10 min, 250 rpm & no & 250 & 10 \\ ECZ, 20 min, 250 rpm & no & 250 & 20 \\ ECZ, 30 min, 250 rpm & no & 250 & 30 \\ ECZ, 10 min, 350 rpm & no & 350 & 10 \\ ECZ, 20 min, 350 rpm & no & 350 & 20 \\ ECZ, 30 min, 350 rpm & yes & 350 & 30 \\ ECZ-MAG, 10 min, 250 rpm & yes & 250 & 10 \\ ECZ-MAG, 20 min, 250 rpm & yes & 250 & 20 \\ ECZ-MAG, 30 min, 250 rpm & yes & 250 & 30 \\ ECZ-MAG, 10 min, 350 rpm & yes & 350 & 10 \\ ECZ-MAG, 20 min, 350 rpm & yes & 350 & 20 \\ ECZ-MAG, 30 min, 350 rpm & yes & 350 & 30 \\ \hline \end{tabular}
\end{table} 
Table 1: Overview of experimental conditions. The actual mass loss was compared with the theoretical value predicted by [PERSON]'s law. The theoretical electrode loss based on [PERSON]'s law, meaning the theoretical amount of dissolved metal, was calculated as follows:  
\[\text{C}_{\text{theor electrode}}=\frac{\text{I}\cdot\text{t}\cdot\text{M}_{ \text{w}}}{\text{z}\cdot\text{F}\cdot\text{V}} \tag{3}\]  
where  
I--the current intensity (A),  
t--the process duration (hours),  
M\({}_{\text{w}}\)--the molar mass of aluminum (g/mol),  
z--the number of electrons transferred per mole of dissolved metal during the electrochemical reaction,  
F--[PERSON]'s constant (96487 C/mol). The Faraday efficiency is calculated by Equations (1)-(4):  
\[\text{FE}(\%)=\frac{\text{C}_{\text{actual electrode}}}{\text{C}_{\text{theor electrode}}}\cdot 100 \tag{4}\]  
Faradaic efficiency values may be lower or higher than 100%. Values above 100% suggest super-faradaic dissolution, where additional electrode corrosion--beyond that predicted by [PERSON]'s law--is likely driven by localized chemical or electrochemical processes.