Heavy metals such as lead, arsenic, mercury, nickel, cadmium and hexavalent chromium are among the main contaminants found in industrial and groundwater. Their removal is essential to ensure compliance with environmental regulations and water safety. Depending on the concentration and type of metal present, various technologies can be employed: specific adsorbents, membranes or physico-chemical treatments.

Removal Technologies Based on Concentration

1️⃣ For low concentrations of heavy metals (trace amounts or a few mg/L)

• Selective adsorbents: advanced materials such as zeolites, ion-exchange resins or special porous materials capture metal ions, reducing their concentration to safe levels.
• Reverse osmosis or nanofiltration membranes: these separate heavy metals by retaining them in the concentrate, thereby producing purified water with high efficiency.

2️⃣ For medium or high concentrations (tens or hundreds of mg/L)


• Chemical-physical treatments: coagulation, precipitation and flocculation enable metals to be converted into insoluble compounds that can be easily separated.
• Chemical reduction processes: specifically for metals such as hexavalent chromium, which is converted into trivalent chromium and precipitated.

3️⃣ For effluent with very high concentrations (above 500 mg/L)


• Precipitation with sulphides or hydroxides: forms solid compounds that can be separated by sedimentation or filtration.
• Sludge filtration and dewatering: to reduce the volume of the residue produced by physico-chemical processes.

Advantages of the Integrated Approach

• Selection of the most suitable technology based on the concentration and type of metal.
• High efficiency, with the potential to achieve very low emission limits.
• Applications across various industrial sectors, such as electroplating, chemicals, electronics and the treatment of contaminated groundwater.
• The option to combine multiple treatment methods, such as adsorbents and membranes, to minimise residues and disposal costs.

The integration of these technologies ensures effective and sustainable water treatment, enabling compliance with environmental standards and the recovery of valuable resources from the treated water.