16 Nov 2020

Long-Term Stability and Efficacy of Historic Activated Carbon (AC) Deployments at Diverse Freshwater and Marine Remediation Sites

Abstract: A number of sites around the United States have used activated carbon (AC) amendments to remedy contaminated sediments. Variation in site-specific characteristics likely influences the long-term fate and efficacy of AC treatment. The long-term effectiveness of an AC amendment to sediment is largely unknown, as the field performance has not been monitored for more than three years. As a consequence, the focus of this research effort was to evaluate AC’s long-term (6–10 yr) performance. These assessments were performed at two pilot-scale demonstration sites, Grasse River, Massena, New York and Canal Creek, Aberdeen Proving Ground (APG), Aberdeen, Maryland, representing two distinct physical environments. Sediment core samples were collected after 6 and 10 years of remedy implementation at APG and Grasse River, respectively. Core samples were collected and sectioned to determine the current vertical distribution and persistence of AC in the field. The concentration profile of polychlorinated biphenyls (PCBs) in sediment pore water with depth was measured using passive sampling. Sediment samples from the untreated and AC-treated zones were also assessed for bioaccumulation in benthic organisms. The data collected enabled comparison of AC distribution, PCB concentrations, and bioaccumulation measured over the short- and long-term (months to years).

11 Aug 2020

PUBLICATION NOTICE: Autonomous QUerying And PATHogen Threat Agent Sensor System (AQUA PATH): Monitoring Source Waters with Geospatially Wirelessly Networked Distributed Sensing Systems

Abstract: Contaminants serve as health risks to recreational water, potable water, and marine life that result in undocumented effects on population exposure. In many areas of the world, the concern lies in contaminated drinking water, which would immediately effect social and economic order. As research advances for innovative solutions, the deployment of automated systems for source water monitoring could reduce the risk of exposure. Water quality monitoring typically involves sample collection and analyses that are performed in a laboratory setting. These results are normally presented after an 18−48 hr period. This report details the prototyped Autonomous QUerying And PATHogen threat agent sensor (AQUA PATH) geoenabled system that is able to detect the presence/absence of pathogenic bacteria indicators in source waters and report these values in the field, in less than 30 minutes. The AQUA PATH system establishes rapid field data collection and reports assessment of source waters bacterial loads at near shore inner coastal locations, which makes a leap forward compared to current presence/absence tests standards established by the EPA.

30 Jul 2020

PUBLICATION NOTICE: High-Performance Photocatalytic Degradation of Model Contaminants with Iron Oxide–Based Colloidal Solutions under Broad-Spectrum Illumination

Abstract:  Small molecule contaminants, such as compounds from pharmaceuticals, personal care products, and pesticides, persist through traditional wastewater treatment processes. Heterogeneous photocatalysis with transition metal oxides (TMOs) is an emerging technology for removing these recalcitrant contaminants from wastewater. To leverage this technology, we selectively combined three different TMOs with bandgap energies in different regions of the solar spectrum as a means of harvesting multiple wavelengths of incident radiation to increase the degradation rate of model and real contaminants. Specifically, we combined zincite (ZnO, ultraviolet active), hematite (α-Fe2O3, visible active), and tenorite (CuO, near-infrared active). The combination of tenorite and hematite (2:1 mass ratio) was the most effective, degrading methyl orange with a rate constant of 40±1E-03 min−1. When applied to multicontaminant solutions using laboratory illumination, our multispectral photocatalyst degrades real-world contaminants, methyl orange, carbamazepine, and nitrobenzene, with rate constants of 30±1E-03, 24±1E-03, and 6±1E-03 min−1, respectively. In addition, the material degrades contaminants with a greater efficiency under outdoor solar illumination, with Collector Area per Order values of 4.0, 6.1 and 14.5 kWh/order/m³, for methyl orange, carbamazepine, and nitrobenzene, respectively. These results demonstrate the effectiveness of this approach to purify water for strategic applications.