Introduction
Micropollutants are everywhere in our water: pharmaceutical residues, pesticides, PFAS, endocrine disruptors, biocides. Conventional treatment processes — coagulation-flocculation, settling, sand filtration, chlorination — do not remove them satisfactorily. The question is no longer whether to treat them, but how.
I. Why conventional processes are insufficient
Biological processes degrade biodegradable organic matter but micropollutants pose specific problems: very low concentrations (ng/L to µg/L), chemical stability (PFAS are designed to persist), dissolved nature (invisible to settling), and structural diversity (no universal solution).
Field studies show conventional WWTPs remove an average of 30 to 60% of micropollutants. PFAS pass almost entirely through classical treatment trains.
II. Activated carbon: the reference solution
Activated carbon adsorbs organic molecules via physico-chemical interaction. Two forms: PAC (powdered, added directly to the flow, flexible dosing) and GAC (granular beds, longer contact, higher efficiency).
Performance: 60 to 95% removal for most organic compounds.
Strengths: broad spectrum, proven technology, adaptable as retrofit. Limitations: ineffective on short-chain PFAS, progressive saturation, significant long-term OPEX.
III. Ozonation: the power of oxidation
Ozone (O₃) reacts with organic molecules, degrading them or making them more biodegradable. The O₃/BAC combination is often recommended to maximise removal while limiting by-products.
Performance: 60 to 99% for the most reactive compounds. Effective on pharmaceuticals and endocrine disruptors.
Limitations: energy-intensive, potential bromate formation, reduced effectiveness on PFAS, substantial investment.
IV. Advanced UV processes (UV/H₂O₂)
High-intensity UV combined with H₂O₂ generates hydroxyl radicals capable of degrading a wide range of micropollutants (Advanced Oxidation Processes).
Performance: 70 to 99% for the most reactive compounds. Effective on molecules resistant to ozone.
Limitations: high energy consumption, reduced effectiveness by natural organic matter, residual H₂O₂ may require complementary treatment.
V. Nanofiltration and reverse osmosis
Unlike oxidation or adsorption, NF and RO remove pollutants by physical separation: membranes block molecules by size and charge.
Performance: very high removal rates for PFAS (>95% for RO, >80-90% for NF). The only truly effective technology on short-chain PFAS.
Limitations: high energy consumption, concentrate generation requiring treatment, rigorous pre-treatment required, high investment and operating costs.
VI. Emerging processes
Advanced biofiltration (BAC), electro-oxidation, cold plasma reactors (promising for PFAS, still at pilot scale), and photocatalysis (TiO₂/UV) are complementary options depending on the target compounds.
VII. Technology comparison chart
VIII. Which technology to choose?
The choice depends on: target molecules (PFAS → NF/RO; pharmaceuticals → activated carbon/ozonation; complex cocktail → combination), required removal levels, volume, space constraints, and budget. In most practical cases, the best solution is a combination: activated carbon + ozonation, O₃/BAC, or NF + residual activated carbon.
Conclusion
At Nomado, we integrate activated carbon, compact ozonation and nanofiltration modules into our prefabricated units for drinking water, industrial effluent treatment and advanced TWWR.
FAQ
1. Is activated carbon effective against PFAS? GAC is moderately effective on long-chain PFAS but poorly effective on short-chain PFAS. NF or RO remain the most effective technologies.
2. Does ozonation generate dangerous by-products? Bromates if bromides are present, and NDMA in certain cases. Good process control minimises these risks.
3. Can these technologies be retrofitted into existing installations? Generally yes. PAC and UV/H₂O₂ are the easiest to retrofit.
4. What are the typical additional costs? PAC: 0.05–0.20 €/m³. Ozonation: 0.10–0.30 €/m³. NF/RO: 0.50–2 €/m³.
5. Does Nomado offer these solutions in modular units? Yes, for drinking water, industrial effluent treatment and advanced TWWR.
