Advanced Oxidation of Micropollutants in Water for Water Reuse
Trace concentrations of numerous organic compounds (emerging contaminants (EC), and endocrine disruptor compounds (EDCs)) such as pharmaceuticals and personal care products (PPCP), including prescription drugs and biologics, "nutraceuticals," fragrances, sun-screen agents, and numerous others are reported in various wastewater effluents, and aquatic systems. In addition to these, increasing levels of naturally occurring organic materials (NOM) directly linked to societal nutrient management practices are of serious consequence for managing water resources. These compounds and their bioactive metabolites are continually introduced to the aquatic environment as complex mixtures via a number of routes but primarily through both untreated and inadequately treated sewage. Growing health and environmental concerns have made PPCP of particular interest as long-term exposure to low levels of PPCPs could have adverse effects on aquatic and terrestrial ecosystems and/or human health.
Contrary to the above, wastewater as a resource remains unexploited mainly due to lack of infrastructure, development and evaluation of advanced technologies, and lack of regulation and negative public perception. Conventionally, wastewater is discharged into the environment after removing the majority of suspended solids in primary treatment, and biodegradable organic substances in secondary treatment. Tertiary treatment is required to remove most of the trace persistent organic micropollutants and pathogens. Advanced oxidation processes (AOPs), which produce reactive species like hydroxyl radicals in-situ, are identified as one of the potential technologies for the removal of trace concentrations of organics from various water streams. Traditional water disinfection treatment processes such as ozonation and UV disinfection can easily be retrofitted to accomplish advanced oxidation in both water and wastewater treatment plants. AOPs such as UV, UV/ozone, UV/hydrogen peroxide, etc., have the potential to completely mineralize micropollutants in trace concentrations, however, at the expense of high energy and chemical costs. Partial oxidation of the initial compounds to less stable intermediates is a viable option, if the intermediates readily degrade in the environment and are harmless to humans and the environment. However, partial oxidation of organic contaminants can in some cases result in the formation of intermediates more toxic than the parent compound, and the nature and number of the degradation products will depend on the employed oxidation process, reaction time, and water quality metrics.
This research focuses on developing AOPs for degradation of target micropollutants, and quantifying the accumulated effects of the resulting mixture of compounds on living systems rather than on the precise quantification of their chemical compositions, which is costly and time consuming, and can be futile without the prior knowledge of dose and effect relationship of an intermediate. Bioassay methods based on genotoxicity, mutagenic potential will be developed for use on drinking waters treated with AOP. This is an on-going project where the MITACS global link student will evaluate the effect of water quality parameters on the resulting water quality using bioassay tools.