Removal of microplastics from aquatic systems using the method of electrocoagulation
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Date
2026-07-07
Authors
Πέττα, Νίκη
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Abstract
Microplastic pollution has become an emerging environmental concern in recent decades due to its persistence and potential impacts on aquatic ecosystems and human health. These particles re-main stable in any aquatic system for many years and can easily capture organic contaminants, heavy metals and harmful microorganisms, causing serious impacts to the aquatic ecosystem and to human health. More specifically, microplastics can be easily digested by aquatic organisms due to their small size and all these harmful chemicals can ultimately transfer to humans through the food chain, lead-ing to major health risks. The development of efficient, sustainable, and environmentally friendly treatment technologies is therefore essential to protect water resources and promote sustainable industrial practices.
In this context, the objective of this study was to examine electrocoagulation as a sustainable and environmentally friendly method for the removal of microplastics from aquatic systems. This process relies on the dissolution of metallic electrodes (aluminum or iron) through electrolysis, leading to the generation of metal ions that act as coagulants, promoting pollutant removal through charge neu-tralization, precipitation, and adsorption mechanisms. Unlike traditional chemical coagulation, EC does not require the addition of external reagents, thus reducing operational costs and minimizing environmental impact. In particular the aim was to assess the use of electrocoagulation as a separa-tion method for microplastics in municipal Wastewater treatment Plants (WWTP’s).
The experimental investigation was conducted at the Laboratory of Environmental Systems consisting of the fabrication of PET and LDPE microplastics, their exposure to ageing proce-dures, the characterization of the effect of the ageing procedures on the plastic materials and lastly the parametric analysis of the electrocoagulation experiments. The materials used for this study were physical plastic PET bottles and black LDPE garbage bags. These materials were subjected to ageing procedures in an Environmental accelerated ageing chamber (EA2C) which followed ASTM standards for a cycle of 42 days. Afterwards fragments of the plastic bottles were submerged in liquid nitrogen and pulverized to yield microplastics below 500μm. Following this, specific characterization tech-niques, such as ATR-FTIR analysis, Raman Spectroscopy, Dynamic Mechanical Analysis, Contact Angle, Thermal Conductivity and Zeta Potential were used to investigate the effect of the ageing on the polymers. Through comparative Raman shifts, DMA analysis and thermal conductivity measurements an increase in crystallinity for both polymers was identified, that indicated the beginning of oxidative degradation reactions in both plastics.
Lastly, the electrocoagulation experiments explored the effect of critical parameters using virgin PET microplastics for the optimization of the protocol and then tests with both fresh and aged micro-plastic were conducted to assess their different behavior and compare them. The lab tests evaluated the applied current density (3-17 mA/cm^2), the number of electrodes (6-18) and the initial micro-plastic concentration (100,200,400mg/L). The removal efficiency was calculated using the gravimetric approach. It was observed that all experiments reached removal efficiencies above 85% up to 100% in optimal conditions (18 electrodes, C.D.=3 mA/cm^2) and that aged microplastics showed a better coagulative effect and higher removal efficiencies in comparison. The optimal conditions were cho-sen based on residual aluminum, in accordance with legal guidelines.
Overall, the promising findings of this thesis suggest that EC can be a viable and scalable solution for industrial wastewater treatment of microplastic-contaminated water, providing an efficient, adaptable, and sustainable solution to reduce environmental pollution and promote responsible wa-ter management.
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Keywords
Microplastics, Electrocoagulation, Plastic ageing, Aluminum, PET, LDPE