Spring 2008 EWRE Seminar Series

Thursday, May 1

3:30 PM ECJ 1.204

Robert Nerenberg, Ph.D., P.E.

Assistant Professor, Department of Civil Engineering and Geological Sciences

University of Notre Dame

Total Nitrogen Removal in the Hybrid Membrane-Biofilm Process

The Hybrid Membrane-Biofilm Process (HMBP) is a novel means of achieving total nitrogen (TN) removal from wastewater.  It incorporates oxygen-supplying, hollow-fiber membranes into an aeration tank, making it easily retrofittable into existing activated-sludge treatment facilities.  A nitrifying biofilm develops on the outside of the membranes and, by suppressing bulk aeration, denitrification is carried out by suspended heterotrophs.  Since oxygen is supplied from the biofilm attachment surface, while ammonium and BOD are supplied from the bulk liquid, a unique microbial community structure develops.  We used FISH, microsensors, and modeling to explore the structure and function of the HMBP biofilm for a variety of operating conditions.  We also conducted pilot-scale tests in New York City.  In this presentation, I will provide an overview of this research, with an emphasis on the microbial ecology findings. 

 

Thursday, April 17

3:30 PM ECJ 1.204

Ram Kannappan
BS Chemical Engineering 2001, University of Texas at Austin
MS EWRE 2004, University of Texas at Austin

Combined Effect of Trihalomethanes and Monochloramine on Distribution
System Nitrification

The presence of disinfection byproducts (DBPs) from chlorination has led many utilities to switch to chloramination for the purpose of lowering DBP concentrations. A result of the switch to chloramination has been an increase in distribution system nitrification. In this process residual ammonia (NH3) from chloramine formation is converted to nitrite (NO2-) by ammonia oxidizing bacteria (AOB) and then nitrate (NO3-) by nitrite oxidizing bacteria (NOB). These bacteria and the products of their growth react with residual disinfectant, and the diminished residual allows heterotrophic bacterial growth in the distribution system. A variety of factors affect the onset of distribution system nitrification and not all are fully understood at this time. Recent work has shown that AOB can cometabolize certain DBPs, specifically trihalomethanes (THMs). The byproducts of THM cometabolism are toxic to the AOB and can limit their growth if the concentrations of THMs are high enough. Also, monochloramine itself inhibits bacteria growth and can delay or prevent the onset of nitrification. This research examines the combined effect of THMs and monochloramine on distribution system nitrification.

 

Elizabeth Ojeh

BS Civil Engineering from the University of Ibadan, Nigeria. 

Fueling the Future: The Evolution of Liquefied Natural Gas (LNG) and the Issues and Challenges Ahead

The report reviews global energy trends and needs, based on the Energy Information Administration (EIA) International Energy Outlook Reference Case data. It examines the potential for LNG to become a major primary energy source for meeting the growing global energy needs. Recent developments in technology in each section of the LNG value chain - Exploration and Production, Liquefaction, Shipping and Regasification and Storage, are reviewed and the finding is that these developments signal an expansionary move within the industry and contribute to the globalization of the LNG market.

The issues that challenge the LNG industry, such as safety and security, environmental impact considerations, interchangeability, and market factors such as demand and supply, trade and financing are analyzed. Although each of the issues presenting varying threats and the opportunities, the outlook for the industry still remains positive. 

 

Thursday, April 10

3:30 PM ECJ 1.204

Casey Forrest

B.S. Chemical Engineering (Lamar University)

 

The Effectiveness of Novel Biopolymer Materials for Capping Contaminated Sediments

 

Capping technology is one of the few in-situ technologies available to environmental scientists and engineers to remediate polluted sediments. While capping technology has been applied successfully in some sites, conventional capping technology employs simply passive sand caps. Innovative capping technologies need to be explored to enhance the capabilities of a sand cap. Novel biopolymer materials composed of chitosan, xanthan gum, and guar gum were prepared and applied as a coating to clean sand. The experiments involved testing the ability of these materials to significantly reduce the migration of contaminants from sediment to above water body and to evaluate their suitability as capping materials based on their physical properties.

 

Juan Morán-López

B.S. Biological Systems Engineering (Virginia Polytechnic Institute and State University)

The SWAT Team and Its Master Plan

The City of Austin’s Watershed Protection Department plans to create a hydrologic model for numerous creeks in Austin. Modeling efforts are centered on flood control, erosion control, and water quality. Using ArcSWAT, engineers will model 17 of the city’s creeks and assess the level of degradation in the creeks to prioritize them accordingly. Modeling is done using ArcSWAT; since the program caters mainly to non-point source pollution and rural settings, the city is working to make adjustments that more readily represent an urban setting. When completed, the project will help the Watershed Protection Department with its long-term goal to provide cost-effective and sustainable solutions for water quality management.

 

Thursday, April 3

3:30 PM ECJ 1.204

Carrie Stefanelli

BS, Illinois State University

Anaerobic Treatment of Ethanol Production Wastewater

The “energy return on investment” of ethanol, or the ratio of energy output to non-renewable energy input, has been a topic of hot debate for over 25 years.  The ethanol production process generates a significant amount of wastewater termed “stillage.”  Anaerobic treatment of stillage has the potential to generate a substantial amount of methane, which may be used as an in-plant fuel source.  As a result, less non-renewable resources would be utilized, and the energy return on investment would increase.  This report focuses on anaerobic treatment of stillage, and the potential to use methane to displace non-renewable fuels for the ethanol production process. 

Tyler McEwen

BS, North Carolina State University  

Hydraulic Performance of Bridge Rails in Series:  Rating Curves and Submergence Effects

To ensure ongoing safety on our nations roads, in 1986 the Federal Highway Administration (FHWA) instituted all highway bridges on the National and Interstate Highway Systems must use successfully crash tested bridge rails.  Current TxDOT policy not only states new construction must use successfully crash tested rails, but also bridges subject to rehabilitation.  Rehabilitation includes replacing failed crash tested bridge rail systems with higher rails with less open space.  Also, construction or modification projects within communities participating in National Flood Insurance Program (NFIP) must not increase Federal Emergency Management Agency (FEMA) delineated 100-year floodplains more than 1 foot.  In an effort to study the hydraulic performance of successfully crash tested bridge rails and the potential implications of rehabilitation projects, we used half-scale physical models to produce rating curves and test submergence effects for single bridge rails as well as bridge rails in series.

 

Thursday, March 27

3:30 PM ECJ 1.204

Samuel Sandoval Solis, Ph.D. Candidate

BS Civil Engineering, National Polytechnic Institute, IPN, Mexico

MS Hydraulics, National Polytechnic Institute, IPN, Mexico

Water Management Scenarios for the Rio Grande/Bravo Basin

Due to the scarcity of the water resources in the Rio Grande/Bravo basin, alternative water management policies or “Scenarios” have been evaluated to determine their hydrologic feasibility and the individual or joint benefits to water users in the basin. The policies evaluated are proposals of stakeholders, local water management agencies, technicians, and experts in Mexico and the United States. Scenarios include water rights buybacks, groundwater banking through in lieu recharge, allocation of non-treaty tributary flows toward treaty delivery obligations, and allocation of water savings from agricultural water conservation. For example, the in lieu groundwater banking method is defined by the surface water available in the basin. If there is enough surface water available, recharge is accomplished by curtailing groundwater pumping and providing surface water to water users. On the other hand, if there is not enough surface water, groundwater and surface water are used to meet the water demands. The evaluation model has been constructed in the Water Evaluation and Planning system (WEAP). Various hydrological conditions, such as normal, wet or dry, have been defined to compare the performance of the proposed policies with the current water management policies under different hydrological conditions. The scenarios and their evaluation are presented along with a comparison against the current water management policies.

Yi-Hsiang Yu, PhD Candidate

B.S. Marine Environment and Engineering, National Sun Yet-sen University, Taiwan

M.S. Marine Environment and Engineering, National Sun Yet-sen University, Taiwan

 

Prediction of Flows around Ship-shaped Hull Sections in Roll Using an Unsteady Navier-Stokes Solver

The objective of this research is to model the physics of the separated unsteady viscous flow over a ship-shaped hull section subject to roll motions. A cell center based Finite Volume Method (FVM) scheme is implemented for solving the Navier-Stokes equations subject to the appropriate conditions on the hull and on the free surface. The results from the present scheme are compared with experimental data and results from other methods, FLUENT and a potential flow solver, for different hull geometries. In the case of prescribed roll motion, the highest amplitude of motion studied is 20 degrees. The effects of the hull geometries in damping the hull motions will be presented for three cases: (a) prescribed roll motion, (b) roll decay from an initial displacement, (c) roll motion due to incoming waves.

 

Thursday, March 20

3:30 PM ECJ 1.204

Y. Peter Sheng, Ph.D., Professor, University of Florida

Ph.D. Engineering (Fluid and Thermal Sciences) at Case Western Reserve University

M.S. Engineering (Fluid and Thermal Sciences) at Case Western Reserve University

B.S. Mechanical Engineering at National Taiwan University

 

Hurricane-Induced Coastal Inundation

Seventy-five percent of the U.S. population lives within 100 miles of coastlines. Coastal population and infrastructure, particularly those in the Gulf of Mexico region, are subject to increasing risk of extreme wind, storm surge, and coastal inundation during hurricane seasons. Coastal states including Florida and Texas must develop robust plans to mitigate the risk and damage associated with hurricane-induced coastal inundation. To this end, this presentation provides a review of hurricane-induced coastal inundation. Following a review of the processes (wind, atmospheric pressure, wave, structure, bathymetry, and topography, etc.) affecting coastal inundation during hurricanes, recent progresses in simulation of wave effects and structure effects are presented using simulation results of an integrated storm surge modeling system for recent hurricanes including Isabel, Ivan, and Katrina. A review of several products of coastal inundation simulation – realtime inundation map, NOAA surge atlas, and FEMA Flood Insurance rate Maps is then given. Use of the integrated modeling system to assist Florida’s hurricane response exercise is also described. Future efforts needed to improve these products are discussed.

 

Thursday, March 13

3:30 PM ECJ 1.204

SPRING BREAK

 

Thursday, March 6

3:30 PM ECJ 1.204

Younggy Kim
B.S. in Civil and Environmental Engineering, Korea University, Seoul, Korea
M.S in Civil and Environmental Engineering, Korea University, Seoul, Korea

 A one-dimensional model is suggested to analyze the ionic transport in the boundary layer of an electrodialysis (ED) or electrodialysis reversal (EDR) system. The model can simulate two different steady-state electrochemical systems: a potential drop across the boundary layer and a current density in the system. The model result has proven that the diffusivity of the selected ion plays a more important role than the ionic charge does in the ionic transport within the boundary layer located at a diluate cell and a relatively smaller diffusion coefficient of a cation explains why the separation process is usually rate-limited near an cation exchange membrane. A non-uniform distribution of current density is expected when salt concentation varies along a diluate cell. This implies a two-dimensional model is necessary to explain the ionic movement in a whole ED or EDR system. In operational aspects, a thin boundary layer is desirable in a diluate cell with a sufficient potential drop while a thick boundary layer is favorable in a concentrate cell. An ED or EDR system is recommended to operate under about 90 percent of the limiting current density for its efficiency based on a potential and current density curve. Application of 90 percent of the limiting current density can also significantly reduce the additionally required potential energy to maintain the separation rate with decreased perm-selectivity of a nearby ion exchange membrane. The degree of dependency of the separation rate on a non-ideal ion exchange membrane varies in a wide range among 16 binary systems under a limiting current density condition and NaCl is shown to be relatively sensitive.

Wil Sarchet
B.S. Civil Engineering, Texas A&M University

Effects of a Thin Layer Sand Cap on Bioavailability and Bioaccumulation in Sediments

The use of a thin layer sand cap (under one foot thick) could prove to be an effective management tool for sediments with relatively low contamination levels, such as dredging residuals.  Benefits of a thin layer cap when compared to a thick layer cap include reduced cost, monitoring needs, and environmental impact on waterways.  This study examines the effectiveness of a thin layer sand cap in providing protection from bioaccumulation of contaminants in the benthic community, which could lead to risk in human health.  Microcosm cells were used to simulate an aquatic environment, and different sand cap thicknesses were evaluated.  Additionally, the hypothesis that porewater concentrations can be used to predict bioaccumulation was tested using porewater concentration profiles measured with Solid-Phase Microextraction fibers.  Results show that a thin layer cap is effective in reducing bioaccumulation, and initial analysis indicates that porewater concentrations correlate with bioaccumulation.

 

Thursday, February 28

3:30 PM ECJ 1.20

Li-Jung Chen

B.S., M.S. Environmental Engineering, National Chung Hsing University, Taiwan

Biological Treatment of Hazardous Air Pollutants (HAPs) Emitted from Corn-Based Ethanol Production Facilities

Domestic production of ethanol has expanded dramatically in the past few years as the United States seeks to develop renewable energy sources and replace MTBE as an oxygenate in reformulated gasoline. Formaldehyde and acetaldehyde, generated during ethanol production, are major pollutants of concern since they are classified as hazardous air pollutants (HAPs) and probable human carcinogens. The objective of this research is to evaluate the feasibility of using biofiltration to treat the aldehyde mixtures emitted from ethanol facilities. Experiments were conducted using a biofilter packed with a compost based material. The results indicate that the biofilter can achieve high removal efficiencies of a single aldehyde over the loading ranges typical of ethanol plant emissions. Monod kinetic parameters have been determined from single substrate degradation experiments and will be used in conjunction with lab-scale biofiltration experiments employing aldehyde mixtures to describe the extent of competition in these systems.

 

Vimal Vinayan

B.Tech (Naval Architecture), Cochin University of Science and Technology, India

M.S. (Ocean Engineering), Florida Atlantic University

 

Numerical modeling of surface-piercing hydrofoils

A surface piercing propeller is a type of supercavitating propeller that operates in a partially submerged configuration. These propellers tend to be more efficient than conventional submerged propellers at service speeds of 70-80 knots and are the primary choice of propulsion for high performance crafts. The increase in efficiency at high speeds is achieved as a result of the reduction in appendage drag, lesser restriction on propeller diameter from hull and draft limitations and reduction of blade surface friction and erosion as cavitation is replaced by ventilation. A two-dimensional potential-flow based Boundary Element Method scheme, with fully nonlinear boundary free-surface boundary conditions, is presented to analyze the ventilated flow past blade sections, which can also be seen as 2D hydrofoils, in the entry-phase. Importance is given to the formation of high speed jets along the wetted portion of the hydrofoil. A FLUENT® model based on multiphase Volume-of-Fluid and Mixture Model is also presented and is used to study the effects of viscosity and spray. Preliminary results are presented comparing the BEM and FLUENT models with existing experimental data for the case of a symmetrical surface-piercing wedge for different angles of attack.

 

Thursday, February 21

3:30 PM ECJ 1.204

Dr. Len Imas

Stevens Institute of Technology  

Computational Aerodynamics for High Performance Yacht Sails  

Advances in hybrid approaches comprising commercially-available Navier-Stokes solver technology and structural dynamic modeling of membranes, coupled with the capability allowing for integration of user-defined physics and numerics into the core solvers, have enabled sail designers and research aerodynamicists to implement complex aerodynamic and fluid-structure interaction (FSI) models of sails and increase the fidelity of sail design in high performance yacht racing. As a consequence, recent research activity in this area has seen a decline in model-scale wind-tunnel testing and use of panel-BL (BoundaryLayer) methods for such applications while sail design has advanced and performance has increased in comparison to earlier generation flying shapes. This presentation will describe current trends in aerodynamic and fluid-structure interaction (FSI) analysis of racing sails through examples and will review relevant topics related to (i) mesh generation;

(ii) fluid and structural solver algorithms;(iii) turbulence and transitional flow modeling technology; and (iv) fluid-structure interaction (FSI)and optimization.

 

Thursday, February 14

3:30 PM ECJ 1.204

Allison DenBleyker

BS, Texas A&M University

Air Pollutant Concentration near Texas Roadways

  

Understanding the public health impact of roadway emissions necessitates knowledge of pollutant concentrations near roadways.  Studies in Los Angeles and other cities around the world found elevated levels of pollutants near roadways which fell to background levels exponentially with increased distance from the roadway.   Such data are not available for any roadways in Texas, where on-road fleets and roadway design differ from previously studied locations.   The Texas Commission on Environmental Quality sponsored a team led by the University of Texas to examine CO, NOx, VOCs, PM, UFP and selected carbonyl concentrations near three roadways in the Austin area.  This research focuses on maximum pollutant exposures at the edge of the roadways and the decay profile as one moves downwind of the road.

 

 

Rémi Candaele

BS, Ecole Centrale de Lille

Characterizing flow through porous asphalt

Porous Friction Course (PFC) or porous asphalt is a permeable asphalt layer placed over an impervious pavement. Air void spaces inside the pavement allow rainfall to flow to the base of the porous asphalt and runoff appears at the edges of the pavement. Numbers of benefits of PFC are acknowledged such as reduced hydroplaning and better visibility.  This study focuses on the hydraulic properties of porous asphalt overlays installed by TxDOT at three locations around Austin: Loop 360, FM1431 and FM620. Air void content and hydraulic conductivity have been measured through different laboratory methods on extracted cores. Results have revealed a substantial clogging phenomenon of the PFC samples.

Thursday, February 7

3:30 PM ECJ 1.204

Tina Stanard

BS, University of Texas at Austin

Porous Asphalt and all its glory
 
Permeable Friction Course (PFC) is a porous asphalt overlay that is placed over an existing impervious base. The interconnected voids of the overlay allow rainwater to drain down into the pavement and then out to the edge of the pavement along the boundary with the impervious base. Benefits of PFC include noise reduction and improved driving safety in wet weather conditions due to less spray, reduced hydroplaning and increased skid resistance. PFC also improves stormwater quality due to possibly reducing the generation of pollutants and retaining a portion of the pollutants within pores of the pavement. This research investigates the stormwater quality improvements through monitoring at two sites located on Loop 360 in Austin, Texas. Concentrations of TSS and total lead, zinc, copper and phosphorous are found to be significantly lower in runoff from PFC than from conventional pavement. The benefits of PFC are lost when the pores in the pavement become clogged. Through ongoing monitoring, the functional life of the pavement will be established.
 

Katie Alfredo

BS, Cooper Union University

How important is research ethics for engineers?

The topic of research ethics may appear to be well researched and defined, but how these codes and guidelines specifically affect graduate engineering students still remains a grey area.  The prevalence of plagiarism scandals and the internal debate about whether words or data as a product are an engineer's main concern give weight to the argument that a more structured method of teaching proper research ethics than mere observation is needed. To address this issue an NSF sponsored project is underway.  Through a review of the literature, faculty and student focus groups, and a pilot survey the place of UT students on the ethical scale is being studied.  Using the information gathered, the research team is creating instructional modules tailored to the topics facing most graduate engineering students in an attempt to engage more of the research community in this ongoing conversation about proper research ethics.

 

Thursday, January 31

3:30 PM ECJ 1.204

Rebecca Teasley, Ph.D. Candidate

BS Environmental Resources Engineering, Humboldt State University

MS Environmental and Water Resources Engineering, University of Texas at Austin

Cooperative Game Theory for Transboundary River Basins: The Syr Darya Basin

Water resources management is a complex and varied topic which is further complicated when a water source is shared by more than one countries. With over 200 transboundary river basins shared by two or more countries, it is important to develop tools to allow riparian countries to cooperatively manage these shared water resources. Cooperative game theory provides methods for quantifying the value of cooperation across jurisdictional boundaries through a suite of mathematical tools that measure the benefits of that cooperation among basin stakeholders. Cooperative game theory also provides methods to fairly and equitably allocate the gains of that cooperation to all participating stakeholders. Cooperative game theory has been applied to the Syr Darya basin as a three player cooperative game. Benefits are determined for varying levels of cooperation among the three major players in the basin.

 

Heather Simon, PhD Candidate

B.S. Earth Systems, Stanford University
M.S.E Environmental and Water Resources Engineering, University of Texas at Austin

 

Modeled Effects of Observed Nitryl Chloride Concentrations in the Houston Area

The recent TexAQS II field study involved intensive air pollutant measurements over Texas during the summer and fall of 2006. During TEXAQS II, NOAA researchers measured concentrations of nitryl chloride of up to 1 ppb in the Houston urban area. Nitryl chloride is potentially important to atmospheric chemistry in urban environments because its photolysis products include both NO2 and chlorine radicals. Chlorine radicals have previously been shown to significantly increase ozone formation in urban Houston. If the values of nitryl chloride measured in Galveston Bay are widespread, this compound has the potential to significantly affect the local reactive chlorine budget and ultimately ozone mixing ratios. Photochemical modeling was performed using the comprehensive air quality model with extensions (CAMx) to investigate the possible effects of measured nitryl chloride concentrations on local chemistry. CAMx was modified to include nitryl chloride and its photolysis reaction (the dominant loss mechanism of this compound). The photochemical modeling runs were performed for a series of days during the TEXAQS II study. After an initial 3 day ramp-up period, model runs were stopped at 7am every morning (the approximate time of sunrise). At that time, measured concentrations of nitryl chloride were inserted into the modeling domain in the nine by nine grid cell region around the measurement point (a 36 km2 region). The parcel of air which contained the initial nitryl chloride concentrations was followed throughout the day. Chlorine radical and ozone concentrations in this model run were compared to those predicted in a basecase model run which did not include any nitryl chloride.

 

Thursday, January 24

3:30 PM ECJ 1.204

Susan K. De Long

Ph.D. Candidate

Development of Molecular Biology Tools for Biological Perchlorate Treatment

 

Perchlorate is a widespread groundwater contaminant that is known to cause adverse health effects such as thyroid dysfunction in humans. Biological treatment is a promising treatment option because perchlorate-reducing bacteria (PRB) are common in the environment and are likely to be present at perchlorate-contaminated sites; the feasibility of biological perchlorate treatment using biologically active carbon (BAC) filters has been demonstrated at the pilot-scale. Many PRB have been isolated that reduce perchlorate to chlorate, and then to chlorite, using perchlorate reductase (pcr). Chlorite, a toxic by-product, is converted to oxygen and chloride using chlorite dismutase (cld). However, successful biological treatment requires not only that the PRB are present, but that they are also actively expressing perchlorate-reducing genes (e.g., pcr and cld) and degrading perchlorate. Changes in the microbial community can lead to process failures; however, few tools currently exist to diagnose these problems. Molecular biology tools, such as quantitative reverse transcription polymerase chain reaction (PCR), might be used to track the expression of perchlorate degradation genes as a function of water quality conditions and process operating parameters, and they even have the potential to detect upsets in the microbial community before process performance is adversely affected. Sequences for pcr and cld have been reported in the literature for a number of phylogenetic groups (e.g., Dechloromonas, Dechlorosoma), and PCR primers have been designed based on these; however, these primers might not detect all PRBs present. For example, while Azospirillum PRB have often been found at perchlorate-contaminated sites, they were not considered in the design of these primers since their perchlorate-reducing genes have not been sequenced. Therefore, we recently developed a tool called Prokaryotic cDNA Subtraction that can be used to obtain the sequences of biodegradation genes from bacteria. We are currently applying this tool to obtain perchlorate reducing genes from bacteria isolated from a perchlorate contaminated site. These sequences will be used to design PCR primers for monitoring bioreactors treating perchlorate contaminated water.

 

Thursday, January 17

3:30 PM ECJ 1.204

Glenn Morrison

Associate Professor of Civil, Architectural and Environmental Engineering

Missouri University of Science & Technology

 

Using chemical activity in materials to reconstruct pollution histories and improve exposure analysis

 

“If the walls could talk, what stories they would tell.” From the perspective of public health, this popular phrase expresses my contention that useful information about past chemical exposure is stored in the nearby materials that witness the event. If the walls could indeed surrender that information, a great deal would be learned about recent contaminant history. We all know that building materials store some information about chemical exposure in indoor environments. When you walk into a room where cigarette smoking has recently occurred, you know that someone in the recent past was smoking; all you needed was your nose. I believe that a more sophisticated analysis will reveal a treasure-trove of information about recent pollution episodes. In this presentation, I will show how we can derive the chemical exposure history of an environment by measuring chemical concentration profiles within nearby materials, such as vinyl flooring, concrete and even trees. The key to mastering the past is to mathematically reconstruct exposure events from the residual contaminant concentration gradients. Contaminants adsorb and absorb into nearby porous solids and immediately begin diffusing into them. Diffusion in uniform materials is well understood, and we can predict the resulting internal concentration gradient if we know the external concentration time-history. To learn about past events, it is necessary to solve an “inverse diffusion problem”. Having shown that these systems have unique mathematical solutions, we are now working towards useful solution methods. I will show early results of this work and also discuss results to date measuring concentration gradients in vinyl flooring, wood and polyurethane foam. I will also discuss applying these techniques to identify asthma promoters in homes with children, monitor groundwater remediation progress, investigate vapor intrusion into buildings and develop passive badges for dynamic personal monitoring of pollutants.

 

 

Fall 2007 EWRE Seminar Series

Thursday, November 29
3:30 PM ECJ 1.204

Con Pelekani, Ph.D.

Senior Process Engineer, Water Treatment Design Group

South Australian Water Corporation

Design, Operating and Research Experience at the Penneshaw Seawater Desalination Plant, South Australia

 

The South Australian Water Corporation is a wholly-owned public water utility, responsible for the management of water and wastewater supply, treatment and distribution infrastructure, for more than 90% of the state's population (~ 1.2 million people). Amongst its infrastructure, SA Water operates a 300 m3 /day seawater reverse osmosis (SWRO) desalination plant for the island coastal community of Penneshaw. Desalination was established as the most cost-effective supply option, when the existing source water, an open dam on a farmer's property, was deemed a very high microbiological risk to humans, particularly with respect to Cryptosporidium and THM formation. SWRO was determined to provide lower cost water than constructing a new pipeline to connect with treated water from an existing conventional water treatment plant in the mid-west of the island.

Built in 1998, the SWRO plant has provided an opportunity to develop a knowledge base for the design and operation of seawater desalination issues. Driven by the environmentally sensitive nature of the local marine environment, the requirement for the plant to be 'chemical-free' has resulted in numerous challenges for process design. The current operating recovery of the RO membrane system is low (by world standards), at 28%, in an attempt to mitigate calcium carbonate scaling. Mechanical integrity issues with the use of 15" diameter pressure vessels resulted in a shift to established conventional 8" RO membrane elements, with significant improvements in plant operation. An improved understanding of seawater corrosion issues and the critical importance of reliable and robust pre-treatment filtration and post-treatment conditioning systems have been positive outcomes from the various upgrades to the plant undertaken from 2001-2005.

In 2005 a research program was initiated to improve our understanding of the relevant fouling mechanisms of the open intake feed water on the RO membranes. The results confirmed significant biofouling activity, even with a pre-treatment system incorporating UV disinfection. Pre-treatment efficacy was found to be reasonable, especially in light of the absence of coagulant addition. Most SDI measurements were below 4, with more than 50% below 3. HPC count analysis using marine agar yielded a removal efficiency near 90%. However, the removal of transparent exocellular particles was relatively poor for bacteria (< 5%). Removal of clumps was far more efficient (>85%). In relation to inorganic fouling, quantitative mass balances for key chemical species across the membrane system did not adequately predict the dominant inorganic foulants, when compared with the analysis of spent chemical cleaning solutions.

An acid dosing trial, undertaken in early 2005 to assess operational, water quality and environmental impact from operating at a higher recovery (40%), confirmed positive performance benefits. With the existing 'chemical-free' process regime, a discharge permit was not required for the waste concentrate.

Seawater RO desalination will become an integral component of SA Water's strategy for securing its customer's future water supply needs. Improved understanding of what unit processes work best for seawater pre-treatment will help contribute significant financial savings for large-scale projects.

 

Con Pelekani Bio

 

Senior Process Engineer

Water Treatment Design Group (SA Water)

Con Pelekani graduated with Bachelor in Chemical Engineering (First Class Honours) from the University of Adelaide in 1995. A recipient of an Australian Fulbright postgraduate scholarship, he completed Master of Science (Environmental Engineering) and Ph.D. (Environmental Engineering) degrees, specialising in water and wastewater treatment, from the University of Illinois at Urbana-Champaign, USA, in 1997 and 1999, respectively. His doctorate focused on the role of adsorbent pore size distribution on the competitive adsorption of synthetic organic micropollutants and natural organic material in drinking water on activated carbon.

Con joined the Engineering & Projects group in January 2002. Reporting to the Principal Process Engineer (Water), Con is responsible for providing an efficient and responsive investigation, design and advisory service for capital works projects and operations, while developing and maintaining leading-edge capability on all aspects of drinking water quality and treatment. His key areas of expertise include process design, membrane technology for water and wastewater purification (including desalination), MIEX ® DOC process, water conditioning and activated carbon adsorption.

Prior to joining the Engineering group, Con worked for 2 years as a research officer in the Water Treatment Unit at the Australian Water Quality Centre (a wholly owned business unit of SA Water). His key responsibilities included laboratory and pilot-scale investigations of the MIEX ® DOC process, investigation of conventional and alternative treatment processes for the removal of dissolved organic material from drinking water, investigation and development of novel desalination processes and providing technical advice to internal and external clients on aspects of drinking water quality and treatment.

Con is a member of Engineers Australia, a member of the Australian Water Association a corporate affiliate member of the International Desalination Association.

 

Thursday, November 15
3:30 PM ECJ 1.204

Matt Harold
B.S. The University of Missouri - Rolla, Geological Engineering

 

Groundwater remediation is a costly and time consuming undertaking, which starts with a guess and often ends with one too.  Much time and effort is spent developing cleanup technology, yet very little time is spent maximizing the operation of those technologies. This issue of inefficiency in operation is addressed through the development of a product maximizing/price minimizing model. Using the API LNAPL Distribution and Recovery Model (LDRM) and the Burdine and Mualem LNAPL relative permeability models, the model developed here seeks to solve a remediation systems optimal operation schedule through goal-seeking. Six groundwater recovery wells were modeled side by side using recoverable volume and transmissibility functions. The model was then run to optimize product recovery, through the use of both pump and treat methodology and free product skimming, while minimizing bulk groundwater removal (used as a substitute for cost). In light of initial modeling success, further work is planned with the goal of producing a more dynamic model. The eventual goal is an approach to recovery optimization modeling which can be easily tailored to any remediation system and any set of operational requirements.

Stephanie Johnson 
B.S. Civil Engineering  and B.S. Environmental Engineering University of Wisconsin - Platteville
M.S. Civil Engineering (water resources emphasis) University of Minnesota

A General Approach to Bacteria TMDL Development: Texas Gulf Coast

 

Numerous bays and rivers along the Texas Gulf Coast are listed on the US Environmental Protection Agency's (EPA) Section 303(d) List for bacterial impairments.  The Texas Commission on Environmental Quality is interested in developing a general approach for completing bacteria Total Maximum Daily Load (TMDL) studies on these bays and the watersheds that drain into them.  Existing modeling techniques are being combined with methods previously approved by the EPA, recommendations set forth in the June 2007 "Bacteria Total Maximum Daily Load Task Force Report", and emerging technologies to create a procedural outline of steps to be taken and tools to be used when completing these studies.  Procedures are being developed within the framework of national datasets to encourage transferability and application outside of the immediate study area.     

 

Thursday, November 1
3:30 PM ECJ 1.204

Jasmine G. Dufreche, M.S. Student
B.S. Civil Engineering, University of Louisiana at Lafayette

Organoclays for the Capping of Contaminated Sediments

Conventional capping of contaminated sediments with sand or other inert materials may not be effective in areas where sediments contain nonaqueous phase liquids (NAPLs) due to displacement or continued migration of NAPLs. The NAPL may migrate as a result of the disturbance associated with capping of the sediment, subsequently during consolidation or as a result of gas release. Organoclays can be an especially effective means of addressing migration of NAPLs and mobile dissolved phase hydrophobic organic compounds. The use of organoclays in laboratory, field demonstration and full-scale field applications will be reviewed. The effectiveness of organoclays in these applications will be summarized. Approaches to effectively place the material in the field will also be summarized.
The potential for organoclay as a capping material will be evaluated primarily on the basis of laboratory measurements of flow and sorption characteristics of organoclay after exposure to water, gas and NAPLs. Organoclays were found to provide good control of both dissolved and nonaqueous phase contaminants. Contact with organoclay gave rise to significant swelling of organoclays and a simultaneous reduction in effective permeability of the organoclay. This could serve to enhance effective utilization of organoclays by forcing lateral migration around seeps but also discourage subsequent migration of NAPLs into a treatment layer. Implications of these results for the design and implementation of organoclays for NAPL control in sediments were assessed.

Virginia Smith, M.S. Student
B.S. Civil Engineering, Georgia Institute of Technology

Throughout the various regions of the United States, droughts have had severe impacts.  Several monitoring and mitigation tools exist to give insight into drought conditions throughout the country.  Currently, the National Oceanic and Atmospheric Administration is developing a National Integrated Drought Information System (NIDIS) to improve drought monitoring and mitigation.  In concurrence with this tool, the state of Texas is developing a Texas Integrated Drought Information System (IDIS).
The goal of the Texas IDIS is to produce a website that will provide information and warnings concerning drought within the state.  The website will obtain climate and hydrologic information and display it in a functional manner.  This requires the development of webservices to integrate data from multiple sources.  To establish this information system the Trinity River Basin and Lake Grapevine have been used as a prototype.  The IDIS uses satellite data, drought indices, stream gage data and reservoir data to portray trends in drought progression through time.  This allows for drought monitoring and classification on a river basin or county scale.  In addition, a new survey interpolation technique has been used to extract a more precise bathymetry of Lake Grapevine.  The precision of the bathymetry permits for a more precise analysis of the amount of water available in the reservoir.

Thursday, October 25
3:30 PM ECJ 1.204

W. Andrew Jackson, Ph.D., P.E.
Texas Tech University
Associate Professor of Civil and Environmental Engineering

Production, Deposition, Occurrence, and Fate of Atmospherically  Generated Perchlorate

Perchlorate (ClO 4-) occurrence in groundwater has previously been linked to industrial releases and the historic use of Chilean nitrate fertilizers. However, recently a number of occurrences have been identified for which there is no obvious anthropogenic source. The possibility that ClO 4- occurrence in surface and groundwater may have multiple origins (military, industrial, agricultural, or natural) complicates site characterization and efforts to assign responsibility for remediation.   Other complications arise when assessing potential human exposure to ClO4-, especially if affected waters are used for drinking, livestock or irrigation of food crops. For example, human exposure to ClO 4- has been documented in vegetation and in dairy milk. Our research shows that perchlorate is produced in the atmosphere likely from reactions of Cl- or ClOx with O3 . This ClO4- is deposited through wet and dry deposition worldwide at low rates.  In arid areas this deposition has accumulated along with other atmospherically deposited species resulting in a significant reservoir (up to 1kg/ha) of natural perchlorate present in the unsaturated zone of semi-arid and arid areas of the Southwest in the United Sates and potentially the world. The perchlorate is highly correlated to chloride concentrations which are known to have accumulated throughout the Holocene. This reservoir of perchlorate is sufficiently large to have a substantial impact on groundwater where irrigation from agriculture or urbanization is sufficient to flush accumulated salts. The final fate of deposited ClO 4- is controlled by the subsurface vertical transport, microbial degradation and plant uptake.  This relatively unexplored source may help to explain the growing reports of perchlorate in produce, milk, and other food items and should be considered when evaluating overall source contributions or drinking water standards.

 

Thursday, October 18
3:30 PM ECJ 1.204

Thomas Pavlovic, Ph.D. Candidate
B.S. University of Zagreb, M.S. Civil Engineering UT Austin

Impact on Ozone Formation from Sources with Variable Emissions of Highly Reactive Volatile Organic Compounds

In the Houston area (HA), ground level ozone concentration can very rapidly reach unhealthy levels. The analysis of the sampled ambient data revealed that plumes of highly reactive hydrocarbons coming from the Houston industrial sites are those mainly responsible for the  rapid ozone formation in the area. Ozone yields in these industrial plumes are roughly three times greater than those measured in the Houston urban plume. The study will test two major hypotheses.
First, the variability of emissions of industrial facilities, which are major sources of highly reactive hydrocarbons, plays a significant role in ozone chemistry in the HA. Second, the current modeling studies suggest emission reductions are more efficient when applied on actual continuously variable source, which most of the industrial sites are. Although HA is the focal point of this study, the basic modeling framework could be applied in other areas of the United States as well.

Gookyoung Heo, Ph.D. Candidate
B.S. Seoul National University

HOx radical chemistry in Southeast Texas: Diurnal variations and spatial distributions of OH and HO2

Scientifically robust and feasible State Implementation Plans (SIPs) contribute to improving air quality for human heath, and prevent the EPA from cutting off federal highway funds and bringing more severe regulations on air emissions as well. Air quality modeling supports SIP preparation processes by providing scientifically acceptable information; therefore, photochemical modeling has been used in preparing ozone (O3) SIPs for the state of Texas for a long time.
Highly reactive radicals, OH and HO2, are key players in ozone pollution phenomena. However, significant under-predictions of OH and HO2, compared to the measurements during the Texas Air Quality Study 2000, have been found recently. In this study, concentrations of odd hydrogen radical (HOx; OH and
HO2) in eastern Texas were simulated by using the Community Multiscale Air Quality model with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (CMAQ-MADRID). In the CMAQ-MADRID modeling, two different chemical mechanisms, Carbon Bond IV (CB-IV) and Regional Acid Deposition Model (RADM2) were used. The modeling period was a September 13 through 20, 1999 photochemical episode that occurred during the Big Bend Regional Aerosol and Visibility Observational (BRAVO) study. In this presentation, diurnal variations of OH, HO2, and the ratio of OH to HO2 will be compared between modeling results from CB-IV and RADM2, and also between modeled concentrations and measurements to clarify the limitations of two chemical mechanisms in modeling OH and HO2 correctly. In addition, spatial distributions of OH, HO2, and ratio of OH to HO2 will be shown.

 

Thursday, October 11
3:30 PM ECJ 1.204

Alison Skwarski, M.S. Student
BS Environmental Engineering, Michigan Tech University

Below the biologically active layer within sediment environments, porewater concentrations drive contaminant fluxes.  Measuring porewater concentrations can provide an understanding of contaminant mobility and migration.  However, low concentrations encountered in porewater can lead to difficulties in sampling and analysis.  Solid-phase microextraction (SPME) has recently become a standard approach for extracting organic analytes from aqueous samples and studies have also shown it to be effective for sampling sediment porewater.  While SPME contains many unique features, including the ability to detect extremely low concentrations and significantly reduce solvent consumption during extraction, many uncertainties still exist concerning the accuracy of this technique.  This presentation will focus on the laboratory demonstration plan for using solid-phase microextraction to measure porewater concentrations.  The overall goal is to move SPME from the laboratory into the field where porewater measurements can be taken in-situ.  Along with the approach for sampling and analyzing porewater concentrations, two studies will demonstrate the use of SPME as a field tool.

Shane Walker, Ph.D. Candidate
BSCE, Texas Tech University
MSE, University of Texas at Austin

As global freshwater sources become increasingly scarce, the development of non-traditional drinking water resources, such as desalination, becomes important.   The improvement of desalination technologies over the past several decades is promising, but challenges in process recovery limitations, environmental hazards, and financial feasibility remain.   This research investigates the performance of electrodialysis as an inter-stage treatment process to improve the recovery of typical brackish groundwater reverse osmosis treatment systems.

 

Thursday, October 4
3:30 PM ECJ 1.204

Brad Eck, M.S. Student
B.S. Mechanical Engineering, Texas Tech University 

Runoff from areas of bare soil, such as those found at construction sites and quarry operations impairs the quality of receiving waters by contributing suspended solids and other constituents.  These areas must be stabilized and vegetation established before a Notice of Termination can be submitted to regulators.  The objective of this project was to compare the stabilization performance of two composts (low and high organic matter), a wood based hydromulch, and seeded bare soil and to determine the amount of sediment and nutrients exported from each type of treatment. Ten test plots (8 feet x 40 feet) were constructed on a spoil pile at a quarry.  Water quality and quantity data were collected for 12 storms during the first year after installation.
The data indicate that the compost mixtures were most successful at establishing vegetation, with almost full coverage after about four months. Runoff coefficients for the two types of compost were similar and about half that observed for the hydromulch and control plots, which were not significantly different. Water quality monitoring showed that the compost plots reduced the sediment discharge compared to the bare plots by about 97%. Even though both treatments reduced the load of total phosphorus discharged, dissolved phosphorus loads from all the treated plots were much higher than observed for the bare soil plot.

Yongseok Hong, Ph.D. Candidate
M.S. Civil Engineering, Korea University, Seoul, Korea
B.S. Civil Engineering, Korea University, Seoul, Korea

In sediments, metals are often contained in insoluble low bioavailability forms.  Upon re-suspension, however, biogeochemical processes associated with the exposure to more aerobic conditions may lead to transformation and release of the metals, giving rise to exposure and risk in the water column. Further, tidal and other cyclic variations in oxygen, pH and other relevant parameters in the overlying water, may also lead to cyclic transformations and release of metals from surficial sediments. To understand the dynamics of the metal transformation and release processes and identifying the significance of these processes in the environment, a one dimensional diagenetic model was developed, focused on heavy metal speciation in sediment by implying surface complexation
model. The model was compared with previously published experimental data and applied to zinc contaminated estuarine sediment to investigate the effect of overlying water pH changes in zinc release.

 

Thursday, September 27
3:30 PM ECJ 1.204

Lisa Moretti, M.S. Student
Tufts University, B.S. Environmental Engineering

A full-scale field study was conducted at the McCormick and Baxter Superfund Site in Portland, OR to test the efficacy of using an active cap of organoclay to control seepage.   The McCormick and Baxter Site is a former creosoting facility located along the Willamette River.  Free-phase creosote had been detected in the river due to off-site migration of creosote.   To prevent creosote from seeping into the Willamette River, a sediment cap was installed which incorporated the use of organoclay in known seepage areas. Organoclay is a modified-clay with organophyllic properties that can sorb non-aqueous phase liquid (NAPL).   The organoclay cap was evaluated 1-year after implementation to assess the cap performance.  This presentation will outline the testing procedures and results from the post-implementation study.

Donghyun Rim, Ph.D. Candidate
M.S. Civil Engineering, University of Texas at Austin
B.S.  Civil Engineering, Hanyang University, Seoul, Korea

Elevated exposure to indoor air pollutants can pose serious potential risks to the occupant health. Inhalation exposure to gaseous and particulate pollutants is associated with respiratory and cardiovascular disease as well as with the transmission of airborne infectious diseases such as tuberculosis and SARS. Knowing the pollutant transport mechanisms in indoor environment is necessary for developing exposure prevention measures. The objective of the study is to examine applicability of Computational Fluid Dynamics (CFD) for analysis of airflow and pollutant transport in an occupied space. The study is based on controlled experiments and numerical modeling. The experimental mock-up tests provide the basis to establish a reliable numerical model, which is used for investigating the temporal and spatial pollutant concentration in distinct environmental conditions. The study evaluates different ventilation strategies for controlling occupant exposure. Furthermore, the study identifies important factors which should be adjusted in CFD models to predict the transient pollutant concentrations with an acceptable accuracy.

 

Thursday, September 20
3:30 PM ECJ 1.204

Dr. Mary Jo Kirisits , Ph.D.
Assistant Professor

Lab Safety Practices

Many Environmental and Water Resources Engineering graduate students work in the laboratories, and we want this to be a safe experience for everyone involved.  The purpose of this seminar will be to highlight important aspects of chemical and biological laboratory safety, including things that you should do and things that you should not do.

Clark Siler, M.S. Student
B.S. , Brigham Young University

WRAP Display Tool: ArcGIS Interface to the WRAP Model

The Texas Commission on Environmental Quality (TCEQ) uses computer simulated water availability models to predict if water will be available for new or amended water rights. The Water Rights Analysis Package (WRAP), created by Dr. Ralph Wurbs of the Texas Water Resources Institute (at Texas A&M University), is the primary water availability model used by TCEQ. The WRAP Display tool, developed by the Center for Research in Water Resources (CRWR), is an update to an existing ArcGIS tool used to display the results of WRAP simulations in a geographic information systems (GIS) environment. This tool converts the formatted text (ASCII) WRAP output into a geodatabase and subsequently displays map and time series data found therein. These functions allow for automated access to and display of cryptic simulation output data. Furthermore, the geographic display afforded by the tool may reveal spatial relationships not readily shown in the raw text output. Finally, the marriage of the WRAP output to the ArcGIS environment provides a platform of additional data transformation and sharing through various editing and export options.

 

Thursday, September 13
3:30 ECJ 1.204

Pat McNamara , M.S. Student
B.S. Marquette University

Reducing Polymer Usage at Hornsby Bend Biosolids Management Plant

Hornsby Bend Biosolids Management Plant treats sludge from Austin’s two wastewater treatment plants.  Prior to composting, the sludge must be dewatered to 18% solids; polymer is used to aid in this dewatering.  During the last fiscal year, over $500,000 were spent on polymer, a significant increase compared to the $300,000 spent the previous year.  The objective of this research is to determine ways that polymer usage can be reduced at Hornsby Bend.  Plant data for the past several years were analyzed to delineate the problem.  Optimal polymer dosing was studied on both the bench and full scale.  The future work involves running lab-scale anaerobic digesters to test effects of influent solids concentration and detention time. 

Tony Smith , Ph.D. Candidate
B.S. California Polytechnic State University

Evaluation of Biodegradation Potential in Contaminated Sediment to Determine Effectiveness of Capping

A sediment cap is being considered for the remediation of Onondaga Lake in Syracuse, New York.  The long-term effectiveness of the cap is dependent upon the ability of indigenous bacteria to degrade the contaminants of interest.  Twelve sediment cores from the southeast end of Onondaga Lake were tested for the biodegradation of BTEX, chlorobenzenes, and naphthalene by native bacteria.  Pore water was extracted from cores by centrifugation then analyzed for concentrations of major ions.  Pore water chemistry was reproduced in sediment slurries of either 1% solids (w/v) in aerobic conditions or 5% solids in anaerobic conditions.  Contaminants were added to give a starting concentration of 1 mg/L.  Slurries were incubated at 12°C and 22°C and contaminant concentrations were monitored for 3 – 5 months.  Biodegradation was observed in most neutral pH slurries but not in alkaline slurries.  Rates of gas generation in each core were also measured to assess the likelihood of gas-induced contaminant transport through the sediment cap.

Thursday, September 6
3:30 PM ECJ 1.204

Alexandria Boehm
Assistant Professor, Environmental Engineering and Science
Stanford University

Oceans and Human Health: Microbial Pollution of Coastal Waters

In the USA, there were 20,000 beach advisory and closure days caused by elevated densities of fecal indicator bacteria (FIB) in 2005, up from 6,200 in 1999. These figures suggest that pollution of America's coastline is widespread, threatening the health of visitors who collectively make 930 million trips to the beach each year, and the tourism and recreation industries (the most rapidly growing sectors of the ocean economy). The majority (over 75%) of the advisories in the nation is caused by "unknown" pollution sources, limiting efforts to remediate contaminated coastal waters. Thus, uncovering FIB sources and elucidating how they may impact coastal water quality needs to be a top priority for coastal scientists and engineers.

I will illustrate how interdisciplinary studies using tools from molecular biology, coastal oceanography, and groundwater hydrology can elucidate important sources of FIB to nearshore waters. My lecture will include discussion of three important sources of FIB to nearshore waters, beach sand, polluted groundwater, and ebb flow from coastal lagoons, and the mechanisms via which they are transported from source to sea.

 

Thursday, August 30
3:30 PM ECJ 1.204

Jay Regan
Assistant Professor, Civil and Environmental Engineering
The Pennsylvania State University

The Ecology of Microbial Fuel Cell Anode Biofilms

Microbial fuel cells (MFCs) harness the electrochemical activity of certain microbes for the production of electricity from biodegradable compounds, ranging from purified substrates such as acetate and glucose to complex wastewaters and cellulosic biomass.   This technology enables the capture of some of the energy stored in waste materials, presenting the potential for energy neutral or yielding waste treatment.   While the power densities of these systems are still quite low relative to electrochemical fuel cells, they have increased by six orders of magnitude over the past decade largely due to improvements in reactor design that reduce the system internal resistance.   With these advancements, the biocatalytic constraints at the anode biofilm are becoming rate limiting.  A general model for anode reduction is that it is catalyzed by dissimilatory metal reducing bacteria, which make their living in natural systems by respiring extracellular minerals.   Pure-culture tests with model iron reducers such as Geobacter and Shewanella spp. demonstrate the electrochemical activity of these bacteria, but the power densities achieved in these pure-culture systems is generally less than mixed-culture systems, perhaps due to synergistic interactions within the anode communities and the participation of currently unknown strains and mechanisms.   My group has been using nucleic acid based techniques to characterize MFC anode biofilm composition and evolution.  In some MFC systems we retrieve DNA sequences from known metal- and anode-reducing bacteria, but some biofilm communities show a dominance of bacterial groups with unknown phenotype.   Bioprospecting with a novel isolation strategy has yielded unexpected isolates with iron- and anode-reducing capabilities, with some isolates approaching the power densities of mixed-culture systems.   We are currently exploring biofilm architecture features, with the goal of better understanding this relatively unexplored microbial ecology to allow the engineering of biofilms that promote higher current densities.