Comparative Review of Heavy Metal Removal Technologies in Industrial WastewaterDr. Hossein Ataei FarAmbassador for Sustainability at SPSC | Wate...
Published on by Hossein Ataei Far, Ambassador for Sustainability at SPSC
Dr. Hossein Ataei Far
Ambassador for Sustainability at SPSC | Water & Energy PPP Finance & Contracting Facilitator| Gold Badge Ambassador, Silicon Valley Innovation Center Network | Member of The Water Network by AquaSPE (Ranking: 9.2/10)
September 29, 2025
Introduction:
Heavy metals (density > 5 g/cm³, e.g., arsenic, lead, mercury) are toxic and persistent pollutants that pose serious health risks, including organ damage, cancer, and developmental disorders. Regulations strictly limit their discharge to protect public health and ecosystems.
Article content
Values are based on WHO and EPA guidelines; regional limits may vary (enclosed table)
2. Treatment Methods
Conventional Processes:
Chemical Precipitation: Metals precipitate as hydroxides; simple, low-cost, effective for high concentrations (>1000 mg/L); produces sludge.
Flotation: Air bubbles separate metals; rapid, effective for dilute solutions; requires surfactants.
Ion Exchange: Resin-based; selective and efficient; high cost and potential fouling.
Electrochemical Deposition: Metals deposited on the cathode; minimal sludge; energy-intensive.
Innovative Physico-Chemical Processes:
Adsorption: Novel high-surface-area materials (MOFs, graphene, MXenes, biochars); efficient at low concentrations; regenerable.
Membrane Filtration (UF/NF/RO/FO/MD): Pressure-driven separation; compact; fouling and cost challenges.
Electrodialysis: Selective ion removal; recovery possible; energy-intensive.
Photocatalysis: UV/visible light activates catalysts; degrades organics and recovers metals; emerging technology.
3. Comparative Table of Methods (enclosed table)
4. Key Findings (Post-2020 Literature & Saleh et al., 2021)
Hybrid and integrated systems improve efficiency, reduce sludge, and enable metal recovery.
Novel adsorbents (MOFs, graphene, MXenes, biochars) exhibit high lab-scale performance for low-concentration metals.
Photocatalysis shows promise for simultaneous organic degradation and metal recovery.
Electrodialysis and selective ion-exchange focus on resource recovery and circular economy potential.
Membrane technologies are advancing, though fouling and operational costs remain barriers.
Low-cost biochars and agricultural wastes are increasingly used for decentralized and low-income applications.
Research focus is shifting toward techno-economic assessment (TEA), life-cycle impact, and real effluent testing.
5. Practical Implications
High metal loads (>1000 mg/L): Lime precipitation or hybrid systems with recovery.
Trace / low concentrations: Advanced adsorbents, membranes, and hybrid photocatalysis/electrochemical polishing.
Scale & economics: Lab-scale performance promising; pilot-scale validation with TEA and life-cycle assessment required.
6. Post-2020 Technology Comparison Table (enclosed table)
Key Insights:
High-concentration effluents → lime precipitation or hybrid systems.
Trace/low-concentration effluents → advanced adsorbents, membranes, or photocatalysis.
Emerging technologies require pilot-scale validation and TEA before full-scale adoption.
Resource recovery is increasingly prioritized, aligning with circular economy goals.
7. Conclusion
Heavy metal contamination in industrial wastewater requires a balanced approach integrating conventional and innovative treatment technologies.
Summary of Key Points:
Current Applications: Adsorption (novel materials) and membrane filtration dominate due to efficiency and adaptability.
Future Potential: Photocatalysis offers sustainable, dual-function treatment with pollutant degradation and metal recovery, pending scale-up.
High Metal Loads (>1000 mg/L): Lime/chemical precipitation is effective, particularly when integrated with recovery systems.
Selective Recovery: Ion exchange, electrodialysis, and electrochemical deposition enable targeted metal recovery, supporting circular economy approaches.
Selection Criteria: Optimal technology choice depends on pH, metal concentration, treatment efficiency, sustainability, cost, technical simplicity, and recovery potential. Hybrid systems can maximize performance by leveraging complementary advantages.
Overall Insight: Post-2020 research emphasizes not only removal but also resource recovery, environmental sustainability, and techno-economic feasibility, enabling a shift from mere treatment to responsible, circular wastewater management.
8. References
[1] Barakat, M.A., New trends in removing heavy metals from industrial wastewater, Arabian Journal of Chemistry, 2011.
[2] Qasem, N.A.A. et al., Removal of heavy metal ions from wastewater, 2021, Nature.
[3] Juve, J.M.A. et al., Electrodialysis for metal removal and recovery: a review, 2022, ScienceDirect.
[4] Kumari, H. et al., A Review on Photocatalysis Used For Wastewater Treatment, 2023, PMC.
[5] Jadoun, S. et al., A review on adsorption of heavy metals from wastewater, 2023, ScienceDirect.
[6] Carmona, B., Abejón, R., Innovative Membrane Technologies, 2023, MDPI.
[7] Saleh, T.A., Mustaqeem, M., Khaled, M., Water treatment technologies in removing heavy metal ions from wastewater: A review, 2021, Environmental Science.