Atrazine and simazine removal mechanisms by nanofiltration: Influence of natural organic matter concentration

Experiments on a semi-industrial scale on the removal of atrazine and simazine by nanofiltration have demonstrated the influence of natural organic matter (NOM) on the retention of these two s-triazines. In-depth studies at pilot scale, presenting the advantage of working on a larger range of NOM concentrations (or dissolved organic carbon: DOC), have given a better understanding of the principal phenomena involved in atrazine and simazine retention mechanisms in the presence or absence of NOM. When taken together, the results show that the principal transfer mechanism of the two s-triazines is probably through diffusion. However, their complexation with NOM leads, on the one hand, to an increase in their apparent molecular weight and, on the other, to the appearance of negative charges. As a result, electrostatic repulsion and adsorption are also phenomena to be considered. At pilot scale, atrazine and simazine removal by nanofiltration increases from 50% to 90–100% when the waterʹs NOM content varies from 0.4 to 3.6 mg 1−1 of DOC.