Fly bioash accelerates dissipation dynamics of the herbicide terbuthylazine in the aquatic matrix

Pesticides often become emergent chemicals in aquatic systems shortly after application. As one of the widely used broad-spectrum herbicides, terbuthylazine (TBL) has been frequently detected in all types of natural waters. TBL is a lipophilic compound that tends to adsorb to organic matter in soil and has a high runoff potential to surface waters, where it dissipates very slowly under natural conditions. To date, remediation of TBL-contaminated surface waters has relied on challenging and variably effective processes such as physical adsorption to activated carbon, photocatalytic degradation by titanium oxide, ozonation, and bioremediation. Therefore, there is an economic need to explore the effectiveness of remediation of contaminated matrices using less expensive agents, especially industrial by-products such as biomass ash. In- depth characterization of wood fly ash (FA, from a modern cogeneration power plant facility), using state-of-the-art in situ approaches (Scanning Electron Microscopy, X-ray diffraction) raised the hypothesis that highly developed nano- microstructure and alkaline Ca/Mg/Si-enriched mineralology of FA could be effectively used for removal of TBL from the watercourse. This study showed that FA addition at 1% w/v rate to the watercourse sample reduced the half-life of TBL from 14 days to 9 h vs. the control (distilled water) treatment. TBL was not detected in the alkaline (pH 12.4) treatment 48 h after the addition of FA, while in the control TBL remained at nearly 80% of its initial amount. These results show a promising starting point for the development of novel FA-based polymers, targeted for decontamination of aquatic ecosystems loaded with TBL and similar contaminants.