Influence of organic matter on atrazine rejection by nanofiltration
Ducellier, Frederic Michel
Master of Science
The influence of Natural Organic Matter (NOM) on the removal of atrazine by nanofiltration was studied using pressurized dead-end filtration cells. The effect of several parameters, physical and chemical, was investigated to identify the interactions between the NOM and atrazine. Any changes of the physical parameters leading to an increase in concentration polarization, such as stopping the stirring, produced a decrease in rejection of atrazine. No significant pressure effect was observed for the conditions evaluated in this study. The chemistry of the feed solution also influenced the removal of atrazine. The presence of organic material appeared to enhance atrazine rejection by the membrane. The extent of this process varied with several factors: the atrazine to TOC ratio (smaller effect at higher atrazine to TOC ratio), the nature of the organic matter (higher removal observed for tannic acid compared to the NOM) and the calcium concentration at low ionic strength in the presence of tannic acid. The model presented in this work consistently underestimated the initial concentration of atrazine. It also gave better predictions in the absence of organic matter and failed to predict most of the data obtained with tannic acid.