Journal of Environmental Engineering

Bridge deck runoff sometimes directly discharges through deck drains to water bodies. As such, the runoff is usually not treated; however, recent pressures have led Departments of Transportation to install closed pipe drainage systems beneath bridges to deliver stormwater to a stormwater control measure (SCM). This can be costly both in terms of up-front and long-term maintenance capital. This study compared bridge runoff concentrations of nutrients, sediment, and heavy metals to effluent concentrations from six commonly used SCMs. Runoff quality samples from 15 bridges in North Carolina were collected and compared to those from 41 different SCMs across North Carolina. The SCMs examined in this study were permeable friction course (PFC) overlays, wet retention ponds (WP), bioretention cells (BRC), vegetated filter strips (VFS), constructed stormwater wetlands (CSW), and grassed swales (GS). Bridge deck runoff concentrations were not statistically different from SCM effluent concentrations for total nitrogen (TN). For total phosphorus (TP), all SCMs produced effluent concentrations lower than bridge runoff concentrations, although only PFC, BRC, and WP did so significantly. For total suspended solids (TSS), median effluent concentrations from the SCMs were significantly and substantially lower (a difference of more than $15\mathrm{mg}/\mathrm{L}$) than those from bridges. Comparison against water quality threshold concentrations developed for North Carolina suggested that BRC and WP were best for TN treatment and that PFC, WP, and BRC were appropriate for TP treatment. For TSS, all six SCMs were capable of improving the bridge runoff. Similar results were observed for copper, lead, and zinc; BRC, GS, and CSW were able to reduce total metals concentrations significantly. Dissolved metal concentrations appeared difficult to reduce with current SCM technology. These results suggest that for certain pollutants, treatment of bridge runoff may yield improvement. However, the appropriateness of installing SCMs to treat bridge deck runoff must account for the increased cost of closed pipe drainage systems beneath bridges and limited space in the right-of-way and weighed against the relative ease of retrofitting stormwater treatment infrastructure into other transportation corridors.

This study evaluated the slurry phase biological treatment of a latosol, collected at a contaminated site from a plasticizers industry, containing high concentrations of alcohols, phthalates, and dioctyl adipate. The test was carried out in a bioreactor open to atmosphere with the sludge from the industrial wastewater treatment plant at 18–26°C during 120 days. The dynamics of the microbial populations during biodegradation were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis. The results suggested that the genera Pseudomonas and Gordonia polyisoprenivorans were the dominant populations until 30 days, Corynebacterium, between 30 and 90 days, and Corynebacterium and Gordonia polyisoprenivorans after 90 days. The addition of sludge and water in the reactor improved the phthalates and adipate bioavailability, initially present in the plasticized soil, and consequently, the pollutant’s removal efficiencies were above 90%. The 2-ethyl hexanoic acid, a toxic metabolite of di-2-ethylhexyl phthalate biodegradation, was completely degraded in 120 days. The most persistent pollutant was di-isodecyl phthalate, which has substituted the di-2-ethylhexyl phthalate nowadays. The pH and the temperature did not need to be corrected, which represents cost savings in soil remediation.

The distribution of residual dense nonaqueous phase liquid (DNAPL) in the subsurface plays a critical role in the DNAPL dissolution kinetics. However, measuring residual DNAPL at the field scale in fractured bedrock settings is generally impractical. This research uses a three-dimensional (3D), bench-scale, fractured-rock network comprised of low-porosity sandstone to evaluate the dissolution kinetics of tetrachloroethylene (PCE) DNAPL at residual saturation during ambient groundwater conditions. To our knowledge, this work presents the first experiments to investigate DNAPL dissolution in 3D bench-scale fractured systems. DNAPL dissolution in the relatively uniform fracture network was evaluated and described using an effective parameter, the bulk mass transfer coefficient ($K_L$). Results from dissolution experiments revealed a positive, statistically significant correlation between $K_L$ and DNAPL-water interfacial area, and between $K_L$ and DNAPL saturation, analogous to porous media experiments. While aperture size and uniformity influenced DNAPL trapping and interfacial area in the fracture network experiments, DNAPL-altered aperture size did not have a statistically significant influence on dissolution rates. The mass transfer behavior for our 3D fracture network was more similar to one-dimensional (1D) porous media experiments than to two-dimensional (2D) and 3D porous media experiments, which primarily used nonaqueous phase liquid (NAPL) pools. This result is likely due to a combination of the coexistence of the nonwetting NAPL phase and the flowing-aqueous phase in the larger fractures or at fracture intersections, as well as better mixing due to dynamic flow pathways in the network. Finally, residual NAPL saturations could not be replicated in the networks, possibly due to the unpredictable flow-switching behavior of multiphase fluids in fractured rock.

Air sparging (AS) is an in-situ groundwater remediation technique for volatile organic compounds (VOCs) in contaminated sites. Knowledge of effect of the injected air on air flow patterns and extent of the zone known as zone of influence (ZOI) is crucial for design of in situ air sparging. The two main objectives of this research are to study transition of air flow patterns and characteristics of ZOI under different air injection pressures during centrifugal tests and to find the scaling factors for centrifugal tests under different gravitational levels ($N$ times gravitational force). In this research, the modeling of models test was first performed to validate centrifugal technique for simulating air sparging. Then, a set of two-dimensional (2D) centrifugal modeling tests were performed under various gravitational levels to study the transition of air flow patterns and characteristics of ZOI during air sparging. The centrifugal model tests showed that the observed 2D ZOI was truncated-cone under various gravitational levels. It was also observed that flow pattern for the same soil transits from channel flow under lower gravitational levels to bubble flow under higher gravitational level. If there are same air flow regimes during air sparging tests under varied gravitational levels, then the scaling factor for air sparging is $N$, and a formula was proposed to check the flow regime. In this research, a formula was proposed to explain the transition of air flow patterns during air sparging and determine the boundary of flow regime transition based on grain size and unit-sparging rate.

Tannic acid modified super paramagnetic ${\mathrm{Fe}}_3{\mathrm{O}}_4$ nanoparticles (${\mathrm{Fe}}_3{\mathrm{O}}_4\text{-}\mathrm{TAN}$) were synthesized by a simple strategy and were used as adsorbents for removal of methylene blue (MB) from water solution. The prepared magnetic nanoparticles (MNPs) were characterized by Fourier transform infrared (FT-IR), transmission electron microscopy (TEM), thermogravimetric (TGA), and X-ray diffraction (XRD) analyses. The effects of pH, contact time, dye concentration, and temperature on adsorption were determined. The experimental data were analyzed using the Langmuir adsorption model. The data fitted well to the model with maximum adsorption capacities $90.9\mathrm{mg}/\mathrm{g}$ under $\mathrm{pH}=10.5$. Also, the adsorption kinetics and thermodynamic parameters were studied and evaluated. Adsorption of the MB to nanoparticles reached equilibrium after 25 min. In addition, the external magnetic field could easily separate nanoparticles from water with high separation efficiency. Desorption process of the adsorbed dyes was also investigated.

Storm-water pollutants are widely recognized as a major cause of surface water quality degradation. Most storm-water treatment efforts have focused on capture of particles and particle-associated pollutants, but oftentimes half or more of pollutant loads can be attributed to the dissolved phase. Dissolved pollutants are more mobile, bioavailable, and are captured via different mechanisms than particles. Low-impact development storm-water control measures such as bioretention are being used to infiltrate storm water to reduce storm-water volume as well as to capture storm-water pollutants. Bioretention systems have proven effective at capturing both dissolved and particulate storm-water pollutants. Herein the authors present a state-of-the-art review of dissolved storm-water pollutant sources and typical concentrations, removal mechanisms, and fate in bioretention cells covering three pollutant classes: (1) nutrients (i.e., phosphorus and nitrogen), (2) toxic metals, and (3) organic compounds, including emerging contaminants. Also discussed are recent innovations in bioretention design to enhance dissolved pollutant removal, such as media amendments, saturated zones for promoting denitrification, and vegetation for stimulating biodegradation. Current knowledge gaps and recommendations for future research directions are also discussed.

As reservoir simulation models become more widely used, there is greater need for uncertainty assessment in water quality modeling. In comparison with the modeling of quantity phenomena, such as hydrological modeling, water quality modeling involves additional uncertainties in the modeling of pollutant loadings and the transport and fate of contaminants in receiving waters. In this work, a general and flexible method based on generalized likelihood uncertainty estimation (GLUE) is used to estimate the uncertainty in reservoir water quality modeling that arises from parameter uncertainty and error in model inputs. A one-dimensional model which was set up to simulate the hydrothermal and water quality of Pepacton Reservoir, part of the New York City water supply system, was used to demonstrate the method. Obtained results show that most model parameters and inputs follow wide non-Gaussian distributions, indicating they are of high uncertainty. The results also show that uncertainty is low for the simulated water temperatures of the epilimnion and hypolimnion, and dissolved oxygen (DO) of the epilimnion. Unfortunately, the simulation uncertainty for total phosphorus and chlorophyll $a$ of the epilimnion and hypolimnion, and DO of the hypolimnion is high, especially at peak concentrations. These results can be helpful in understanding and improving the model.

An investigation on the influence of temperature (21.6–39.6°C) on the reaeration rate was performed. The recipient still water body was homogeneous and unstratified. The findings of the experimental study showed that the reaeration rate increases with temperature within the range of the temperature investigated. A mathematical model for estimating the reaeration rate is also presented. A new temperature correction factor for the conversion of the kinetic rate coefficient at different temperatures has been developed and was found to better reflect the reaction rates associated with the reaeration process.

Following an EPA recommendation many states switched to Escherichia coli (EC) water-quality standards. However, past data is still in terms of fecal coliforms (FC). EC-FC models are therefore necessary to understand long-term water-quality trends. The predominant method develops a linear relationship between log EC and log FC by minimizing the errors of log EC. These models are difficult to interpret as they are nonlinear. This method also leads to biased model coefficients as log FC is assumed to be error free. The present study develops linear models that do not require predictor identification. The models were developed by minimizing the errors in the logarithmic domain. Linear and log-log models with and without predictor identification were developed for EC-FC data from 10 sites in the lower Passaic River at Paterson, New Jersey. The Nash-Sutcliffe efficiencies (NSEs) of all model types are similar. The authors recommend the use of linear models that do not require predictor identification due to ease of interpretation and better estimate of the true relationship between EC and FC.

The objective of this study was to evaluate at the pilot scale the performance of a chemical leaching process for Pb, Cu, Sb, and Zn removal from a fine fraction ($<125\mathrm{\mu m}$) of soil at two Canadian small-arms shooting ranges (SASR; Batoche: $418\mathrm{mg}\mathrm{Cu}/\mathrm{kg}$, $\mathrm{5,006}\mathrm{mg}\mathrm{Pb}/\mathrm{kg}$, $168\mathrm{mg}\mathrm{Sb}/\mathrm{kg}$, and $96\mathrm{mg}\mathrm{Zn}/\mathrm{kg}$; Normandie: $\mathrm{1,015}\mathrm{mg}\mathrm{Cu}/\mathrm{kg}$, $\mathrm{6,024}\mathrm{mg}\mathrm{Pb}/\mathrm{kg}$, $305\mathrm{mg}\mathrm{Sb}/\mathrm{kg}$, and $177\mathrm{mg}\mathrm{Zn}/\mathrm{kg}$). A comparison of different leaching reagents revealed that the use of ${\mathrm{H}}_2{\mathrm{SO}}_4$ $(0.125\mathrm{M})+\mathrm{NaCl}$ (4 M) is a very promising option from an economic point of view to solubilize metallic pollutants from highly polluted soils. The results showed that chemical treatment, including three successive acid-leaching steps (${0.125\mathrm{MH}}_2{\mathrm{SO}}_4+4\mathrm{MNaCl}$, $\mathrm{PD}=10\%$, $\mathrm{t}=1\mathrm{h}$, $\mathrm{T}=20°\mathrm{C}$) followed by one rinsing step using water [pulp density $(\mathrm{PD})=10\%$, time $(\mathrm{t})=15\min$, temperature $(\mathrm{T})=20°\mathrm{C}$], resulted in metal removal yields of 93% Cu, 97% Pb, 89% Sb, and 70% Zn in Batoche soil and 85% Cu, 96% Pb, 59% Sb, and 49% Zn in Normandie soil. Subsequently, Sb and other dissolved metals (Cu, Pb, and Zn) were successfully recovered via chemical precipitation/coprecipitation (99.1% Cu, $>99.9\%$ Pb, 95.1% Sb, and 99.9% Zn—Batoche; 90.4% Cu, $>99.7\%$ Pb, 79.1% Sb, and $>99.9\%\mathrm{Zn}—\mathrm{Normandie}$) by adding NaOH until $\mathrm{pH}=9$.

Waste from coal cleaning processes includes coarse size fractions (i.e., coarse refuse) and small particles (i.e., fine refuse). The aqueous suspension of fine refuse, referred to as coal slurry, frequently contains potentially toxic substances, including hydrocarbons, heavy metals, and coal cleaning chemicals. Disposal of coal slurry using underground injection has raised environmental concerns because it may lead to contamination of groundwater and water supplies. In the present study, liquid and solid fractions of coal slurries collected from five underground injection sites and one coal preparation site in West Virginia (WV) were analyzed for a suite of 177 organic and inorganic constituents. The original data presented in this article were all collected by the WV Department of Environmental Protection, Office of Mining and Reclamation, and the U.S. Department of Interior, Office of Surface Mining, with input from the WV Department of Health and Human Resources. Several metals of health and environmental concern, including aluminum, antimony, arsenic, iron, lead, and manganese, were detected at concentrations exceeding the U.S. EPA environmental guidelines. Total suspended solids, pH, and inorganic ions, including nitrite, chloride, fluoride, and sulfate, were also measured at levels above the U.S. EPA guidelines at one or more sites. Several volatile and semivolatile organic compounds listed in the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Priority List of Hazardous Substances were positively detected, but at concentrations well below the U.S. EPA environmental guidelines. The present study provides new information about the chemical composition of coal slurry from different sites in WV that will be useful for environmental and health risk assessment.