Research Vision
​My research group pursues in-depth investigations of the fate of emerging contaminants in natural environments and their interactions with microorganisms, soil and sediment components. I expect my research to advance the use of biological processes for the remediation of contaminated sites and to increase the efficiency and sustainability of wastewater treatment processes, to provide information to regulatory agencies, and to shed light on mechanisms leading to the attenuation of contaminants in different environmental matrices.
Current Research Projects
Giving GAC a second chance: Use of retired GAC to treat high-strength primary effluent from a petroleum refinery
Granular Activated Carbon (GAC) is widely used in water treatment plants (WTPs) to remove micropollutants, color, and odor through adsorption. Once its adsorption capacity is depleted, typically every four years in water treatment plants, GAC is either regenerated through energy-intensive thermal treatment or replaced, with spent GAC being disposed of in landfills. Considering that standard GAC is typically made from coal, a non-renewable resource, it is crucial to investigate sustainable alternatives to extend the life of this material. In this study, we are testing the use of spent GAC retired from a WTP as a preliminary treatment for the primary effluent from a petroleum refinery in Texas, which is currently treated in a wastewater treatment plant (WWTP). We are evaluating the effects of empty-bed contact time and two different inocula that have been previously exposed to refinery wastewater on the GAC columns treatment efficiency.
Art by Sidney Segovia
Sewer disposal of reverse osmosis concentrate: Effects on microbial communities in wastewater treatment plants
Advanced wastewater treatment for potable reuse and brackish groundwater desalination have emerged as alternatives to increase water supply and diversify the water source portfolio of several communities across the world, especially of inland communities. These processes rely on the use of membrane processes such as reverse osmosis (RO) to remove salts and trace contaminants from the water, leading to the generation of a reject stream known as RO concentrate. Inland communities face challenges in disposing of RO concentrate since seawater discharge is not a viable option. Sewer disposal of RO concentrate is economically feasible, but it may be disregarded due to concerns that RO concentrate constituents may harm microorganisms performing critical processes in wastewater treatment plants (WWTP) such as organic matter and nutrient removal. This could lead to WWTP effluent that fails to meet the standards specified in the plant’s discharge permit. Although there is evidence that high salinity and high concentrations of contaminants of concern can inhibit microbial processes, there is limited information on the short or long-term effects of exposure of different microbial groups participating in wastewater treatment to RO concentrate. In this project, we aim to assess the inhibition of microbial processes due to exposure to different ratios of RO concentrate to domestic wastewater and investigate mechanisms used by microorganisms to increase protection against high salinity levels and toxic contaminants.
Preparing our current wastewater treatment infrastructure for a future of increasing salinity
Activities such as oil production, industrial processes, fertilizer and road salt application, and seawater intrusion have driven the salinization of our conventional drinking water sources. Consequently, salinity levels in wastewater have also risen. Research shows that increased salinity adversely affects the performance of biological processes in wastewater treatment plants (WWTPs) due to the loss of activity of non-salt tolerant organisms and changes in the sludge settling properties. However, most studies focus on microbial response to very high salinity levels using synthetic wastewater and bioreactor configurations that may not accurately represent the complexity of full-scale municipal WWTPs. In this project, we will focus on the impact of changes in salinity on the removal of conventional and emerging contaminants in WWTPs under realistic conditions. In addition, we will evaluate strategies to overcome microbial inhibition due to high-salinity toxic loads.
