## 3 Results
### Assessment of Process Efficiency: Linking Physico-Chemical Indicators with Process Performance
#### 3.1.1 Comparative Temperature and pH Profiles  
Figure 2 provides the temperature and pH changes during the ECZ and ECZ-MAG processes. Results show that the temperature increase during ECZ and ECZ-MAG is gradual but consistent, and attributable primarily to ohmic heating resulting from electrolyte resistance and Faradaic reactions at the electrodes. Notably, a more pronounced temperature rise is detected in ECZ-MAG systems, particularly for 20 and 30 min durations. For instance, at 250 rpm, the temperature in the ECZ-MAG system rises from 21.7 \({}^{\circ}\)C to 31.9 \({}^{\circ}\)C in 20 min and further to 35.7 \({}^{\circ}\)C over 30 min. This contrasts with the ECZ (non-magnetic) systems, which exhibit comparatively modest thermal increments under identical conditions. The elevated temperatures in ECZ-MAG systems can be ascribed to magnetic field-enhanced mass transport phenomena. However, previous experiments with Fe electrodes [29] showed a slightly lower temperature increase in ECZ-MAG compared to ECZ, indicating that the interaction between the magnetic field and the electrocoagulation system is electrode material-dependent. Regarding the variations in mixing speed between 250 and 350 rpm, results showed no significant impact on temperature rise, suggesting that mixing intensity does not substantially influence heat generation in the system during short-duration treatments. However, it is important to have in mind that excessive temperature rise is undesirable because treated wastewater with elevated temperatures cannot be discharged directly due to the risk of thermal pollution, which can harm aquatic ecosystems. In practical applications, this issue can be effectively managed through engineering controls, such as optimizing the ratio of electrode surface area to wastewater volume being treated. By carefully regulating this parameter, it is possible to limit the temperature increase during treatment while maintaining high removal efficiency, ensuring environmentally safe discharge conditions. Figure 2b illustrates the comparative pH profile. Namely, the EC process inherently influences the pH of the treated solution due to anodic dissolution and subsequent formation of hydroxides [8], thus similarly occurring in the hybrid ECZ and ECZ-MAG  
Figure 2: Temperature changes (**a**) and pH changes (**b**) during the ECZ and ECZ-MAG processes over a process duration of 30 min and for two different mixing speed. Note: standard deviation from the average value for temperature is in the range \(\pm\)(0.1–0.7) \({}^{\circ}\)C, while for pH is in the range \(\pm\)(0.03–0.28). process. As shown in Figure 2b, a sharp increase in pH occurs during the first 5 min across all experimental conditions, rising from an initial pH of 3.95 to around 8.85. The zeolite presence also contributes to this pH increase due to ion exchange of Na\({}^{+}\) from the zeolite structure with H\({}^{+}\) from the water, which may shift the balance of ions in the water, leading to a pH increase [32]. The influence of the magnetic field may accelerate the dissolution of aluminum anodes by enhancing micro-mixing and mass transfer near the electrode surfaces, which may contribute to the rise in pH. However, in our experiment, the differences in pH increase between magnetic and non-magnetic processes, as well as between different mixing speeds, become negligible. This observation slightly differed from our previous study comparing ECZ and ECZ-MAG systems using Fe electrodes for the treatment of compost wastewater with a medium organic load (COD \(\approx\) 865 mg O\({}_{2}\)/L) and an NdFeB magnet of 0.55 T [29], where ECZ-MAG exhibits a slightly higher increase in pH. Similarly, [PERSON] et al. (2006) [33] observed a slightly higher pH increase in magnet-assisted electrocoagulation using Fe electrodes and SmCo permanent magnets (0.16 T) for treatment of wastewater prepared from milk powder.