## 3 Results
### Mechanistic Insights into Electrode Dissolution and Mass Loss
In the initial phase (e.g., after 10 min), the presence of the magnetic field enhances local turbulence and mass transfer near the electrode surfaces, leading to accelerated electrochemical reactions and more pronounced electrode damage compared to the system without the magnet. However, as the treatment time increases (20 and 30 min), the magnetic field demonstrates a protective effect--likely due to flow stabilization, more uniform distribution of reactants, and reduced localized chemical and electrochemical stress on the electrode surfaces. In contrast, ECZ systems without magnetic assistance suffer from  
Figure 7: Electrode microscopic surface analysis (at magnifications 100\(\times\), in bright field) carried out after ECZ and ECZ-MAG processes at mixing speeds of 250 and 350 rpm for durations of 10, 20, and 30 min. time-dependent, progressively worsening electrode damage due to uneven mass transport and localized accumulation of aggressive species, especially at a lower mixing speed. It is important to emphasize that although the magnetic field in ECZ-MAG systems does not have a significant influence on the total mass of the dissolved metal--since the dissolution of the anode is kinetically controlled--it does have a significant influence on the state of the electrode surface after the EC process. In other words, the magnetic field does not increase the overall material loss, but it can reduce localized surface damage, resulting in improved long-term stability and longevity of the electrodes. This effect can be particularly useful for the optimization of electrooagulation (EC) processes, both in terms of removal efficiency and the longevity and cost-effectiveness of electrode materials. A few studies can be found that support the previous observations regarding the influence of magnetic fields on electrode surface morphology and corrosion behavior in EC processes. According to [PERSON] et al. (2022) [18], applying a magnetic field in EC with an Al electrode effectively mitigated electrode fouling during water treatment. The authors attributed this improvement to enhanced mass transfer via Kelvin and magnetohydrodynamic (MHD) effects, which also reduced the resistivity of the accumulated fouling layer by approximately 23%. In our previous study with Fe electrodes [29], the application of a magnetic field increased electrode fouling and induced surface fractures, particularly at 20 min of treatment, which is probably driven by the dissociation and magnetic accumulation of ferromagnetic Fe species influenced by Kelvin forces and MHD convection near the electrode surface. Compared with this study, a clear difference in the behavior of magnetic field influence is observed between systems using Al and Fe electrodes, which can be attributed to several interrelated factors. These include the intrinsic properties of the electrode materials, such as their standard electrode potentials and corrosion behavior, as well as the pH of the system, which affects the speciation and solubility of metal ions. Additionally, the nature and load of the treated wastewater play an important role. In the present study, the compost wastewater treated with Al electrodes exhibited a high organic load (COD\(\approx\)1600 mg O\({}_{2}\)/L), which probably intensifies electrochemical activity at the electrode surfaces, particularly during the initial treatment phase. In the later stages of the process (after 20 and 30 min), a stabilization phase occurs in which the magnetic field promotes a more uniform distribution of ions and flocculants. This leads to the formation of protective layers--such as Al(OH)\({}_{3}\)--that cover micro-damages on the electrode surface. As a result, the intensity of localized corrosion decreases because the reactive zones become \"saturated\", and diffusion barriers are leveled out. Consequently, surface damage becomes less pronounced, especially in terms of pitting, and the electrode surface appears more uniform and compact.