Pilot-Scale Demonstration of an Innovative Treatment for Vapor Emissions

ABSTRACT

Researchers from the National Renewable Energy Laboratory recently conducted a pilot-scale study at McClellan Air Force Base (AFB) in Sacramento, CA. The objective of the test was to determine the effectiveness of an ambient-temperature, solar-powered photocatalytic oxidation treatment unit for destroying emissions of chlorinated organic compounds from an air stripper. This paper reports test results and discusses applications and limitations of the technology.

A 10-standard-cubic-foot-per-minute (SCFM) (28.3 L/min) slip stream of air from an air stripper at Operative Unit 29-31 at McClellan AFB was passed through a reactor that contained a lightweight, perforated, inert support coated with photoactive titanium dioxide. The reactor faced south and was tilted at a 45° angle from vertical so that the light-activated catalyst received most of the available sunlight. An online portable gas chro-matograph with two identical columns simultaneously analyzed the volatile organic compounds contained in the reactor inlet and outlet air streams. Summa canister grab samples of the inlet and outlet were also collected and sent to a certified laboratory for U.S. Environmental

Protection Agency Method TO-14 analysis and verification of our field analyses. Three weeks of testing demonstrated that the treatment system's destruction and removal efficiencies (DREs) are greater than 95% at 10 SCFM with UV intensities at or greater than 1.5 milliwatts/square centimeter (mW/cm²). DREs greater than 95% at 20 SCFM were obtained under conditions where UV irradiation measured at or greater than 2 mW/cm². In Sacramento, this provided 6 hours of operation per clear or nearly clear day in April. A solar tracking system could extend operating time. The air stream also contained trace amounts of benzene. We observed no loss of system performance during testing.     

Historical deposition of mercury and selected trace elements to high-elevation National Parks in the Western U.S. inferred from lake-sediment cores

Atmospheric deposition of Hg and selected trace elements was reconstructed over the past 150 years using sediment cores collected from nine remote, high-elevation lakes in Rocky Mountain National Park in Colorado and Glacier National Park in Montana. Cores were age dated by ²¹⁰Pb, and sedimentation rates were determined using the constant rate of supply model. Hg concentrations in most of the cores began to increase around 1900, reaching a peak sometime after 1980. Other trace elements, particularly Pb and Cd, showed similar post-industrial increases in lake sediments, confirming that anthropogenic contaminants are reaching remote areas of the Rocky Mountains via atmospheric transport and deposition. Preindustrial (pre-1875) Hg fluxes in the sediment ranged from 5.7 to 42 μg m^?2 yr^?1 and modern (post-1985) fluxes ranged from 17.7 to 141 μg m^?2 yr^?1. The average ratio of modern to preindustrial fluxes was 3.2, which is similar to remote lakes elsewhere in North America. Estimates of net atmospheric deposition based on the cores were 3.1 μg m^?2 yr^?1 for preindustrial and 11.7 μg m^?2 yr^?1 for modern times. Current-day measurements of wet deposition range from 5.0 to 8.6 μg m^?2 yr^?1, which are lower than the modern sediment-based estimate of 11.7 μg m^?2 yr^?1, perhaps owing to inputs of dry-deposited Hg to the lakes.     

Solubilities of selected organic electronic materials in pressurized hot water and estimations of aqueous solubilities at 298.15 K

Increasing production and disposal of organic light-emitting diode (OLED) displays for smartphones and tablets may have impact on the environment depending on the aqueous solubility of the pertinent chemicals. Here, aqueous solubilities are presented for several compounds, mostly aromatic amines, used as hole transport materials in the OLED displays. Solute selection includes 1,4-bis(diphenylamino)benzene, tetra-N-phenylbenzidine, 4,4′-bis(N-carbazolyl)-1,1′-biphenyl, 1,3,5-tris(diphenylamino)benzene, and 9,10-bis(phenylethynyl)anthracene. The solubilities are those in pressurized hot water (PHW), i.e., measured at elevated temperature (up to 260 °C) and pressure. The semi-quantitative estimates of room-temperature solubilities of the solutes have been obtained from extrapolations of the solubilities in PHW. For the compounds studied, the estimated aqueous solubilities at room temperature do not exceed 2 × 10^?11 g of the solute per 1 kg of water. Aqueous solubilities of triphenylamine have also been measured and used to upgrade a recent group-contribution model of aqueous solubilities of organic nonelectrolytes with the parameters for the nitrogen atom in aromatic amines.     

Implementation of the ecosystem services approach in Swedish municipal planning

While ecosystem-based planning approaches are increasingly promoted through international and national policies, municipalities are still struggling with translating them into practice. Against this background, this paper aims to increase the knowledge of current advances and possible ways to support the implementation of the ecosystem services (ES) approach at the municipal level. More specifically, we analyze how ES have been integrated into comprehensive planning within the municipality of Malmö in Sweden over the last 60 years, a declared forerunner in local environmental governance. Based on a content analysis of comprehensive plans over the period 1956–2014 and interviews with municipal stakeholders, this paper demonstrates how planning has shifted over time toward a more holistic view of ES and their significance for human well-being and urban sustainability. Both explicit and implicit applications of the ES concept were found in the analyzed comprehensive plans and associated programs and projects. Our study shows how these applications reflect international, national, and local policy changes, and indicates how municipalities can gradually integrate the ES approach into comprehensive planning and facilitate the transition from implicit to more explicit knowledge use.     

Investigation of different treatment techniques for PCDD/PCDF in fly ash

A number of different pretreatment and extraction procedures were compared with regard to recovery of PCDD/PCDF from fly ash. Highest results were obtained using an acid digestion with excess dilute HCl, followed by freeze drying of the residue and hot extraction by toluene.