Principle Investigator

Dr. Alba Torrents 


Use of organic matter to decrease bioavailability of persistant organic pollutants (POPs)


Several highly persistent organic pollutants have been extensively used by industry and agriculture.  While many of them have been banned, many sites still contain levels that pose ecological risks.  Here, we are investigating if adding organic amendments (compost) will reduce the bioavailability of POPs, such as DDT, in soil. We use a combination of field and laboratory studies to help determine the effectiveness and feasibility of composting to mitigate bioavailability and ecological risk. Additionally, we are investigating the fate and spatial characteristics of the DDT using site data and then developing statistical methods to help evaluate an array of environmental data with high spatial variability.

Organic Pollutants and Microplastics


Much is still unknown about the uptake and fate of organic pollutants in microplastics (plastic particles <5mm). The accumulation of these pollutants in microplastics can translate to bioaccumulation in marine organisms, after microplastic ingestion. As this research field is developing, analytical techniques must be standardized in order to carry out ecotoxicological assessments. A significant focus of our work is creating standardized "weathered" microplastics in the lab. These microplastics are then used to evaluate the sorption of organic pollutants.

Organic contaminants in wastewater


The project focuses on the fate of organic pollutants and presence of dehalogenating bacteria throughout the wastewater treatment process.  More specifically, how various treatment processes, such as activated sludge, nitrification, and anaerobic digestion, influence contaminant concentrations and formation of degradation products. This This research is done in conjunction with DC Water and the USDA.

Controlling odorous compounds from wastewater treatment plants


 The goal of this research is to increase the understanding of odor related compound formation and release from primary and secondary systems at an advanced wastewater treatment plant. Specifically, to determine the key parameters impacting sulfur compounds. This involves assessment of the impact of operational conditions and seasonal changes on the dynamics of hydrogen sulfide and methyl mercaptan emissions. The findings will be used to develop better odor control initiatives through operational changes.

Effect of reactive amendments to improve performance of biowalls for remediation of TCE 


This project is consists of a series of experiments to determine which of several mixtures of organic and inorganic materials will create the best biowall to be implemented to remediate TCE (an industrial solvent) contamination in groundwater. In contrast to traditional pump and treat methods, in situ remediation with a biowall (a permeable reactive barrier) could be cheaper and have the desired environmental protection. Biowalls are constructed down gradient of the dissolved contaminated area, and they depend on the groundwater gradient to transport the contaminant through the biowall, where treatment occurs. Results of the biowall tests will be used to design a site implementation plan using the best biowall matrix.

Effects of mercury contamination from illegal gold mining on vegetation


Mercury release as a byproduct of gold mining can be significant, especially in illegal mining efforts, as no mitigation techniques are used. The effect of mercury on local vegetation in the Peruvian Amazon is not well understood. In this research we will determine the toxicity reference value of mercury for some indigenous species of vegetation used for reforestation purposes and agricultural purposes in the region. Additionally, we will examine the bioaccumulation of mercury and the effects of mercury on the productivity of those species. Finally, come study of social impacts of illegal mining will be carried out.