Contaminant mobilization from the vadose zone to groundwater during experimental river flooding events.

Natural river flooding events can mobilize contaminants from the vadose zone and lead to increased concentrations in groundwater. Characterizing the mass and transport mechanisms of contaminants released from the vadose zone to groundwater during these recharge events is particularly challenging. Therefore, conducting highly-controlled in-situ experiments that simulate natural flooding events can help increase the knowledge of where contaminants can be stored and how they can move between hydrological compartments.

Comparison of Zn-Al and Mg-Al layered double hydroxides for adsorption of perfluorooctanoic acid.

Per-and polyfluoroalkyl substances (PFAS), a large class of synthesized chemicals, are persistent in nature and generally recalcitrant to conventional chemical and biological treatment. Adsorption is considered an economical and practical method for PFAS treatment. Layered double hydroxides (LDHs) represent a promising class of mineral-based adsorbents for PFAS removal because of the highly positive charge of their structural layers.

Removal of Arsenate and Chromate by Lanthanum-modified Granular Ceramic Material: The Critical Role of Coating Temperature.

The development of economical, low-maintenance, environmentally friendly and effective water filtration techniques can have far-reaching public health, social and economic benefits. In this research, a cost-effective La-modified granular ceramic material made of red art clay and recycled paper fiber was developed for the removal of two major anionic contaminants, As(V) (arsenate) and Cr(VI) (chromate). La modification temperature significantly impacted the resulting composition and properties of the adsorbents, and thus played a crucial role in the adsorbent performance.

Comparison of the transport of Bacteroides fragilis and Escherichia coli within saturated sand packs.

Pathogens in groundwater accounted for ∼50% of waterborne disease outbreaks in the United States between 1971 and 2006. The fast and reliable detection of groundwater microbial contamination and the identification of the contamination sources are of critical importance to the protection of public health. Recent studies suggested that fecal anaerobe Bacteriodes spp.

Modification of a Ca-montmorillonite with ionic liquids and its application for chromate removal.

Ionic liquids (ILs), due to their low vapor pressure, have been explored as green solvents for organic synthesis. In this study, the uptake of ILs on a high charge Ca-montmorillonite (MMT) and the use of the IL-modified MMT for the removal of anionic contaminants from water were systematically studied. Uptake of ILs by MMT was exclusively resulted from a cation exchange mechanism when the initial IL concentrations were less than the critical micelle concentration (CMC) and the sorbed ILs formed a monolayer conformation on the surface of MMT.

Impact of the exopolysaccharides Pel and Psl on the initial adhesion of Pseudomonas aeruginosa to sand.

In this study, the impact of the exopolysaccharides Pel and Psl on the cell surface electron donor-electron acceptor (acid-base) properties and adhesion to quartz sand was investigated by using Pseudomonas aeruginosa PAO1 and its isogenic EPS-mutant strains Δpel, Δpsl and Δpel/Δpsl. The microbial adhesion to hydrocarbon (MATH) test and titration results showed that both Pel and Psl contribute to the surface hydrophobicity of the cell. The results of contact angle measurement, however, showed no correlation with the cell surface hydrophobicity measured by the MATH test and the titration method.

Effects of outer membrane protein TolC on the transport of Escherichia coli within saturated quartz sands.

The outer membrane protein (OMP) TolC is the cell surface component of several drug efflux pumps that are responsible for bacterial resistance against a variety of antibiotics. In this research, we investigated the effects of OMP TolC on E. coli transport within saturated sands through column experiments using a wild-type E.

Deposition and remobilization of graphene oxide within saturated sand packs.

In this research, we examined the deposition kinetics of graphene oxide (GO) particles within saturated sand packs as a function of ionic strength as well as the remobilization of previously retained GO particles due to chemical perturbation. The retention of GO particles within saturated quartz sand was found to be strongly dependent on ionic strength. At low ionic strength (e.

Influence of enterococcal surface protein (esp) on the transport of Enterococcus faecium within saturated quartz sands.

Enterococcus was selected by US EPA as a Gram-positive indicator microorganism for groundwater fecal contamination. It was recently reported that enterococcal surface protein (esp) was more prevalent in Enterococcus from human sources than in Enterococcus from nonhuman sources and esp could potentially be used as a source tracking tool for fecal contamination (Scott et al., 2005).

Comparison of the Transport of Tetracycline-Resistant and Tetracycline-Susceptible Escherichia coli Isolated from Lake Michigan.

It was recently reported that tetracycline could enhance the mobility of manure-derived Escherichia coli within saturated porous media (Walczak et al. (Water Research 45:1681-1690, 2011)). It was also shown, however, that E.

The effects of starvation on the transport of Escherichia coli in saturated porous media are dependent on pH and ionic strength.

In this research, we investigate the effects of starvation on the transport of Escherichia coli K12 in saturated porous media. Particularly, we examine the relationship between the starvation effects and the pH and ionic strength of the electrolyte solutions used for cell starvation. E.

Effects of phosphate on the transport of Escherichia coli O157:H7 in saturated quartz sand.

Consumption of groundwater contaminated with E. coli O157:H7 has led to several waterborne disease outbreaks over the past decade. A thorough understanding of the transport of E.

Influence of tetracycline resistance on the transport of manure-derived Escherichia coli in saturated porous media.

In this research, tetracycline resistant (tet(R)) and tetracycline susceptible (tet(S)) Escherichia coli isolates were retrieved from dairy manure and the influence of tetracycline resistance on the transport of E. coli in saturated porous media was investigated through laboratory column transport experiments. Experimental results showed that tet(R)E.

Colloid straining within saturated heterogeneous porous media.

The transport of 0.46 μm, 2.94 μm, 5.

Straining of nonspherical colloids in saturated porous media.

We explore the effects of colloid shape on straining kinetics by measuring the filtration of spherical and nonspherical colloids within saturated columns packed with quartz sand. Our observations demonstrate that the transport of peanut-shaped colloids matches the transport of spherical colloids with diameters equal to the minor-axis length of the peanut-shaped colloids. The straining rates of the spherical colloids vary linearly with the ratio of colloid diameter (d(p)) to sand-grain diameter (d(g)) for 0.

Effects of plants on the removal of hexavalent chromium in wetland sediments.

The effect of two wetland plants, Typha latifolia L. (cattail) and Phragmites australis (Cav.) Trin.

Uptake of bromide by two wetland plants (Typha latifolia L. and Phragmites australis (Cav.) Trin. ex Steud).

The successful use of bromide (Br-) as a conservative tracer for hydrological tests in wetland systems requires minimal Br- loss due to plant uptake. The uptake of Br- by two wetland plants, cattail (Typha latifolia L.) and reed grass (Phragmites australis (Cav.