Adsorció de contaminants orgànics persistents en competència amb la matèria orgànica per millorar la reutilització de l’aigua

Abstract

In recent years, due to climate change and increasing water scarcity, there has been a growing

need to promote new technologies for the reuse and regeneration of treated wastewater in

Wastewater Treatment Plants. However, the simultaneous presence of natural organic matter

(NOM) and persistent organic pollutants (POP) in reclaimed water presents a significant

challenge, as meeting high-quality standards requires treatments of varying intensity depending

on the intended final use.

This study evaluates the adsorption capacity of three commercial activated carbons (AC), Airpel,

A1100, and RB3, for the removal of both NOM and POP.

First, the surface chemical properties of the AC were characterized using two techniques: the point

of zero charge (pHpzc) and the Boehm titration method. After characterization, the adsorption

performance of the AC was assessed for the removal of NOM and POP, both independently and

simultaneously, to examine the existence of any competitive adsorption effects.

The experimental results were fitted to two kinetic models: First order and second order, to

calculate the rate constants and correlation coefficients, thereby identifying the best-fitting model

and the AC with the most favorable adsorption kinetics.

Surface characterization results indicated that A1100 exhibited an acidic surface, RB3 a basic

surface, and Airpel a neutral surface.

Regarding adsorption performance, Airpel showed the fastest kinetics for the independent

removal of NOM. Conversely, RB3 exhibited the highest adsorption rates for POP, with triclosan

and chlorpyrifos being the most efficiently removed compounds by all three AC, while atrazine

showed the lowest removal rates.

Lastly, a clear competitive effect between NOM and POP was observed, resulting in reduced

adsorption kinetics and efficiency for both types of compounds. This competitive effect was

particularly pronounced with RB3. These findings suggest that the selection of activated carbon

should be based on the specific contaminants present in the water and the desired treatment

objectives. In addition, further studies could help to better understand the long-term performance

of these materials under real operating conditions

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