UV-Sulfite Based Advanced Reduction Treatment of Disinfection Byproducts and Perfluorooctanoic Acid

Advanced reduction processes (ARP) are a class of chemical treatment processes that target oxidized contaminants in water/wastewater. ARPs operate through the generation of reducing radical species such as the hydrated/aqueous electron (eaq-). UV irradiation of sulfite (SO3^2-) in solution is an effective generation method for eaq-. The photochemistry of sulfite in solution renders the UV/ SO3^2- ARP advantageous for application to water/wastewater treatment. UV/SO3^2- ARP was successfully tested for application to disinfection byproduct removal and perfluorooctanoic acid (PFOA) defluorination. Batch experiments were conducted to develop kinetic data for defluorination of PFOA. A pseudo component kinetic model for stepwise defluorination of PFOA was applied to experimental observations of inorganic fluoride to obtain two rate constants for PFOA defluorination. The effectiveness of UV/SO3^2- ARP was tested under UV-L and excimer lamps. Quantum yields for the process were calculated to be in the range of 0.002 to 0.004 mol/Ein. Presence of radical scavengers such as alkalinity lowered the kinetics and quantum yields for the process. Excimer lamp offered improvement in kinetics but required greater energy input, due to low UV conversion efficiency. Photolytic removal of chlorite (ClO2^-) was investigated under UV-L lamp. Aqueous chlorite photolysis resulted in a reduced form (Cl^-) and an undesirable oxidized form (chlorate, ClO3^-). The effect of background water constituents, natural organic matter (NOM) and alkalinity, on photo degradation of chlorite was studied. Results indicate that NOM significantly reduces chlorate formation by scavenging oxidizing radicals and hindering chlorine dioxide production. The problem of chlorate formation due to high DO in water could be eliminated by applying UV/SO3^2- ARP with high sulfite doses. Batch kinetic experiments for reduction of bromate (BrO3^-) with UV/SO3^2- ARP were conducted. A generic kinetic model for functioning of ARPs was applied to understand the effects of process variables on bromate reduction kinetics. Low wavelength excimer lamp improved BrO3- reduction kinetics significantly, but required an order of magnitude higher electrical energy as compared to the UV-L lamp. The dual effect of NOM is to scavenge reducing radicals and to filter UV irradiance and these effects were examined to determine if they would be significant limitations for application of UV/SO3^2- ARP to natural waters with high NOM concentrations

Comparison of Aermod and ISCST3 Models for Particulate Emissions from Ground Level Sources

Emission factors (EFs) and results from dispersion models are key components in the air pollution regulatory process. The EPA preferred regulatory model changed from ISCST3 to AERMOD in November, 2007. Emission factors are used in conjunction with dispersion models to predict 24-hour concentrations that are compared to National Ambient Air Quality Standards (NAAQS) for determining the required control systems in permitting sources. This change in regulatory models has had an impact on the regulatory process and the industries regulated. In this study, EFs were developed for regulated particulate matter PM10 and PM2.5 from cotton harvesting. Measured concentrations of TSP and PM10 along with meteorological data were used in conjunction with the dispersion models ISCST3 and AERMOD, to determine the emission fluxes from cotton harvesting. The goal of this research was to document differences in emission factors as a consequence of the models used. The PM10 EFs developed for two-row and six-row pickers were 154 + 43 kg/km2 and 425 + 178 kg/km2, respectively. From the comparison between AERMOD and ISCST3, it was observed that AERMOD EFs were 1.8 times higher than ISCST3 EFs for Emission factors (EFs) and results from dispersion models are key components in the air pollution regulatory process. The EPA preferred regulatory model changed from ISCST3 to AERMOD in November, 2007. Emission factors are used in conjunction with dispersion models to predict 24-hour concentrations that are compared to National Ambient Air Quality Standards (NAAQS) for determining the required control systems in permitting sources. This change in regulatory models has had an impact on the regulatory process and the industries regulated. In this study, EFs were developed for regulated particulate matter PM10 and PM2.5 from cotton harvesting. Measured concentrations of TSP and PM10 along with meteorological data were used in conjunction with the dispersion models ISCST3 and AERMOD, to determine the emission fluxes from cotton harvesting. The goal of this research was to document differences in emission factors as a consequence of the models used. The PM10 EFs developed for two-row and six-row pickers were 154 + 43 kg/km2 and 425 + 178 kg/km2, respectively. From the comparison between AERMOD and ISCST3, it was observed that AERMOD EFs were 1.8 times higher than ISCST3 EFs for absence of solar radiation. Using AERMOD predictions of pollutant concentrations off property for regulatory purposes will likely affect a source?s ability to comply with limits set forth by State Air Pollution Regulatory Agencies (SAPRAs) and could lead to inappropriate regulation of the source

Lifecycle Environmental Impact of High-Speed Rail System in the Houston-Dallas I-45 Corridor

Texas has the highest rate of the U.S energy related greenhouse gas (GHG) emissions, and transportation is one of the major contributors. The Houston–Dallas corridor is the busiest routes in Texas. Recently, the development of an intercity High-Speed Rail System (HSR) with Shinkansen N700 series trains has commenced. This study builds the life cycle inventories for vehicles and infrastructure in the HSR system, and conducts a preliminary environmental life cycle assessment. Results indicate that over the design life of the HSR system the total GHG emissions from the vehicle life-time are 9.695 kgCO2eq/VKT, and fossil-fuel usage during vehicle operation is the primary contributor (97%). For the infrastructure, total life-time GHG emissions are 239 kgCO2eq/VKT, out of which, 94% are from the construction stage. Infrastructure is the dominant contributor to end-point impacts in human health category, with 58% of total impact across all damage categories

Lifecycle Environmental Impact of High-Speed Rail System in the I-45 Corridor

Corresponding data set for Tran-SET Project No. 18PPPVU01. Abstract of the final report is stated below for reference: The Houston-Dallas (I-45) corridor is the busiest route among 18 traffic corridors in Texas. The expected population growth and the surge in passenger mobility could result in a significant impact on the regional environment. This study uses a life cycle framework to estimate the net change in environmental impact with the development of a high speed rail system (HSR) along the I-45 corridor. The study follows ISO 14040 principles and standards of life cycle assessment and uses SimaPro 8.5® software and the Ecoinvent 3.3 inventory database. Infrastructure construction, vehicle manufacturing, system operation, and end of life phases are included in the life cycle assessment. The energy and emissions of the system are evaluated per vehicle/passenger-kilometers traveled and compared with the existing transportation modes. The vehicle component accounts for 14.50 kgCO2eq/VKT, of which fossil-fuel usage during operation is the primary contributor with 98% of the greenhouse gas (GHG) emissions. For the infrastructure component, 56.76% of GHG emissions result from the material extraction and processing phase (23.75kgCO2eq/VKT). Life cycle CO2 emissions of this system are 40% lower than comparable systems in Europe, Asia, and North America. The minimum ridership levels required to offset the environmental impact from conventional modes of transport are around 12% and 27% for GHG emissions and NOx emissions respectively. For the stakeholders, policymakers, and community leaders, this study recommends the construction of HSR system between Dallas-Houston, since it does not only save time, reduces traffic jam, and improve passengers’ mobility, but it also saves energy, which benefits the regional environment

Lifecycle Environmental Impact of High-Speed Rail System in the Houston-Dallas I-45 Corridor

Texas has the highest rate of the U.S energy related greenhouse gas (GHG) emissions, and transportation is one of the major contributors. The Houston–Dallas corridor is the busiest routes in Texas. Recently, the development of an intercity High-Speed Rail System (HSR) with Shinkansen N700 series trains has commenced. This study builds the life cycle inventories for vehicles and infrastructure in the HSR system, and conducts a preliminary environmental life cycle assessment. Results indicate that over the design life of the HSR system the total GHG emissions from the vehicle life-time are 9.695 kgCO2eq/VKT, and fossil-fuel usage during vehicle operation is the primary contributor (97%). For the infrastructure, total life-time GHG emissions are 239 kgCO2eq/VKT, out of which, 94% are from the construction stage. Infrastructure is the dominant contributor to end-point impacts in human health category, with 58% of total impact across all damage categories

Zwitterion-Modified Ultrafiltration Membranes for Permian Basin Produced Water Pretreatment

Unconventional oil and gas extraction generates large quantities of produced water (PW). Due to strict environmental regulations, it is important to recover and reuse PW. In this study, commercial polyethersulfone (PES) ultrafiltration (UF) membranes were surface-modified with zwitterionic polymer 3-(3,4-Dihydroxyphenyl)-l-alanine (l-DOPA) solution to alleviate membrane fouling during the ultrafiltration of shale oil PW of the Permian Basin. UF membranes were coated in l-DOPA solution by using a dip coating technique. Membrane characterization tests confirmed successful l-DOPA coating on UF membranes. While performing the experiments, permeate flux behaviors of the uncoated and coated membranes and antifouling resistance of the zwitterionic coating were evaluated. Among the coated UF membranes with varying coating times from one day to three days, the three-day coated UF membrane showed a good flux performance and the highest fouling resistance. The flux reduced by 38.4% for the uncoated membrane, while the reduction was 16% for the three-day coated membrane after the 5 h ultrafiltration of PW. Both improvements of the flux performance and recovery ratio are attributed to a negatively-charged surface developed on the membranes after the zwitterionic coating. The UF pretreatment also improved the flux behavior of the later forward osmosis (FO) process for PW treatment

Long-term meteorologically independent trend analysis of ozone air quality at an urban site in the greater Houston area

<p>The Houston-Galveston-Brazoria (HGB) area of Texas has a history of ozone exceedances and is currently classified under moderate nonattainment status for the 2008 8-hr ozone standard of 75 ppb. The HGB area is characterized by intense solar radiation, high temperature, and high humidity, which influence day-to-day variations in ozone concentrations. Long-term air quality trends independent of meteorological influence need to be constructed for ascertaining the effectiveness of air quality management in this area. The Kolmogorov-Zurbenko (KZ) filter technique, used to separate different scales of motion in a time series, is applied in the current study for maximum daily 8-hr (MDA8) ozone concentrations at an urban site (U.S. Environmental Protection Agency [EPA] Air Quality System [AQS] Site ID: 48-201-0024, Aldine) in the HGB area. This site, located within 10 miles of downtown Houston and the George Bush Intercontinental Airport, was selected for developing long-term meteorologically independent MDA8 ozone trends for the years 1990–2016. Results from this study indicate a consistent decrease in meteorologically independent MDA8 ozone between 2000 and 2016. This pattern could be partially attributed to a reduction in underlying nitrogen oxide (NO_x) emissions, particularly lowering nitrogen dioxide (NO₂) levels, and a decrease in the release of highly reactive volatile organic compounds (HRVOCs). Results also suggest solar radiation to be most strongly correlated to ozone, with temperature being the secondary meteorological control variable. Relative humidity and wind speed have tertiary influence at this site. This study observed that meteorological variability accounts for a high of 61% variability in baseline ozone (low-frequency component, sum of long-term and seasonal components), whereas 64% of the change in long-term MDA8 ozone post 2000 could be attributed to NO_x emission reduction. Long-term MDA8 ozone trend component was estimated to be decreasing at a linear rate of 0.412 ± 0.007 ppb/yr for the years 2000–2016 and 0.155 ± 0.005 ppb/yr for the overall period of 1990–2016.</p> <p><i>Implications</i>: The effectiveness of air emission controls can be evaluated by developing long-term air quality trends independent of meteorological influences. The KZ filter technique is a well-established method to separate an air quality time series into short-term, seasonal, and long-term components. This paper applies the KZ filter technique to MDA8 ozone data between 1990 and 2016 at an urban site in the greater Houston area and estimates the variance accounted for by the primary meteorological control variables. Estimates for linear trends of MDA8 ozone are calculated and underlying causes are investigated to provide a guidance for further investigation into air quality management of the greater Houston area.</p

Life Cycle Environmental Impact of Onshore and Offshore Wind Farms in Texas

The last decade witnessed a quantum increase in wind energy contribution to the U.S. renewable electricity mix. Although the overall environmental impact of wind energy is miniscule in comparison to fossil-fuel energy, the early stages of the wind energy life cycle have potential for a higher environmental impact. This study attempts to quantify the relative contribution of individual stages toward life cycle impacts by conducting a life cycle assessment with SimaPro&reg; and the Impact 2002+ impact assessment method. A comparative analysis of individual stages at three locations, onshore, shallow-water, and deep-water, in Texas and the gulf coast indicates that material extraction/processing would be the dominant stage with an average impact contribution of 72% for onshore, 58% for shallow-water, and 82% for deep-water across the 15 midpoint impact categories. The payback times for CO2 and energy consumption range from 6 to 14 and 6 to 17 months, respectively, with onshore farms having shorter payback times. The greenhouse gas emissions (GHG) were in the range of 5&ndash;7 gCO2eq/kWh for the onshore location, 6&ndash;9 CO2eq/kWh for the shallow-water location, and 6&ndash;8 CO2eq/kWh for the deep-water location. A sensitivity analysis of the material extraction/processing stage to the electricity sourcing stage indicates that replacement of lignite coal with natural gas or wind would lead to marginal improvements in midpoint impact categories

Life Cycle Environmental Impact of Biomass Co-Firing with Coal at a Power Plant in the Greater Houston Area

Electricity generation from coal is one of the leading contributors to greenhouse gas emissions in the U.S. and has adverse effects on the environment. Biomass from forest residue can be co-fired with coal to reduce the impact of fossil-fuel power plants on the environment. W. A. Parish power plant (WAP, Richmond, TX, USA) located in the greater Houston area is the largest coal and natural gas-based power generation facility in Texas and is the subject of the current study. A life cycle assessment (LCA) study was performed with SimaPro&reg; and IMPACT 2002+ method, for the replacement of 5%, 10%, and 15% coal (energy-basis) with forest residue at the WAP power plant in Texas. Results from the LCA study indicate that life cycle air emissions of CO2, CO, SO2, PM2.5, NOX, and VOC could reduce by 13.5%, 6.4%, 9.5%, 9.2%, 11.6%, and 7.7% respectively when 15% of coal is replaced with forest residue. Potential life cycle impact decreased across 9 mid-point impact categories of, human/aquatic toxicity, respiratory organics/inorganics, global warming, non-renewable energy, mineral extraction, aquatic acidification, and terrestrial acidification/nitrification. The potential impact across damage/end-point categories of human health, ecosystem quality, climate change, and resources reduced by 8.7%, 3.8%, 13.2%, and 14.8% respectively for 15% co-firing ratio