Silica-Enhanced Sorbents for Dry Injection Removal of SO2 from Flue Gas

Novel silica-enhanced lime sorbents were tested in a bench-scale sand-bed reactor for their potential for SO₂ removal from flue gas. Reactor conditions were 64°C (147°F), relative humidity of 60 percent [corresponding to an approach to saturation temperature of 10°C (18°F)], and inlet SO₂ concentration of 500 or 1000 ppm. The sorbents were prepared by pressure hydration of CaO or Ca(OH)₂ with siliceous materials at 100°C (101 kPa) [212°F (14.7 psi)] to 230°C (2793 kPa) [446°F (405 psi)] for 15 min to 4 h. Pressure hydration fostered the formation of a sorbent reactive with SO₂ from fly ash and Ca(OH)₂ in a much shorter time than did atmospheric hydration. The conversion of Ca(OH)₂ in the sand-bed reactor increased with the increasing weight ratio of fly ash to lime and correlated well with B.E.T. surface area, increasing with increasing surface area. The optimum temperature range for the pressure-hydration of fly ash with Ca(OH)₂ was between 110 and 160°C (230 and 320 °F). The pressure hydration of diatomaceous earth with CaO did not offer significant reactivity advantages over atmospheric hydration; however, the rate of enhancement of Ca(OH)₂ conversions was much faster with pressure hydration. Scanning electron microscope (SEM) and x-ray diffraction studies showed solids of different morphology with different fly ash/lime ratios and changing conditions of pressure hydration.     

Weekday vs. Weekend Ambient Ozone Concentrations: Discussion and Hypotheses with Focus on Northern California

Abstract

Since the early 1970s, researchers and data analysts have reported differences between weekday and weekend ozone concentrations, with higher ozone concentrations occurring on Sundays in some locations. At that time, the phenomenon was referred to as the “Sunday effect.” In the late 1980s, additional papers focused on weekday/weekend differences in air quality in the South Coast (Los Angeles) Air Basin.

Analyses of ozone concentrations measured at a number of locations in northern California reveal that average ozone concentrations are frequently higher on weekends than on weekdays. Violations of the California 0.09 ppm 1-hour air quality standard for ozone also occur in disproportionately greater frequency on weekends. We hypothesize that this phenomenon is based largely on the differences between weekday and weekend emission patterns. We believe that the observed differences may provide information regarding which pollutant reduction strategy, NO_x or ROG control, may be more effective in reducing ambient ozone concentrations. For the northern California region, the presence of higher weekend ozone concentrations suggests the need for ROG control is greater than for NO_x control. If both NO_x and ROG are to be controlled, it is important to understand the interdependence of the two pollutants in forming ozone. With the current uncertainty and debate regarding official vehicular emission inventories, this phenomenon emphasizes the importance of using observation-based data to examine ambient pollution and emission relationships. This natural experiment of varying emissions provides an interesting test case for sophisticated air pollution model performance and evaluation.

Using a Bay Area emission inventory and an estimate of its change from weekday to weekend, combined with a generic Empirical Kinetic Modeling Approach (EKMA) diagram, we demonstrate the weekend effect. In addition, changes in the Bay Area emission inventory from 1980 to 1990, when combined with the EKMA diagram, also show why the weekend effect is more evident in the 1990s.

It is our hypothesis that the presence of the weekend effect, positive or negative, combined with changes in emission changes, provides a simple clue to whether an area is NO_xor ROG limited with respect to ozone formation.     

CSR in metallurgy sector in Greece: A content analysis

Corporate Social Responsibility (CSR) has become one of the most widespread business topics among the academic community. Various issues like environmental pollution, economic crisis, corruption, poverty are of major importance these days and besides governments and policy makers responsibility it is obvious that corporations are also part of these problems. In Europe the last 15 years, governments, NGOs, small and large enterprises are making an effort to establish in their business CSR strategies so as to become more competitive and innovative in the global market. The research presents the way 8 Greek companies from the metallurgy sector publish CSR activities and which dimensions of CSR are more common among Greek companies. The companies were selected according to a study of ICAP Group about CSR and Leading Employers in Greece. The findings reveal how Greek companies during the economic crisis make their effort to be more active especially on environmental issues, human resources, health and safety and contribution to local communities. The results of their efforts are controversial as far as their CSR strategy concerns.     

Combined effects of constant versus variable intensity simulated rainfall and reduced tillage management on cotton preemergence herbicide runoff

Pesticide runoff research relies heavily on rainfall simulation experiments. Most are conducted at a constant intensity, i.e., at a fixed rainfall rate; however, large differences in natural rainfall intensity is common. To assess implications we quantified runoff of two herbicides, fluometuron and pendimethalin, and applied preemergence after planting cotton on Tifton loamy sand. Rainfall at constant and variable intensity patterns representative of late spring thunderstorms in the Atlantic Coastal Plain region of Georgia (USA) were simulated on 6-m2 plots under strip- (ST) and conventional-tillage (CT) management. The variable pattern produced significantly higher runoff rates of both compounds from CT but not ST plots. However, on an event-basis, runoff totals (% applied) were not significantly different, with one exception: fluometuron runoff from CT plots. There was about 25% more fluometuron runoff with the variable versus the constant intensity pattern (P = 0.10). Study results suggest that conduct of simulations using variable intensity storm patterns may provide more representative rainfall simulation-based estimates of pesticide runoff and that the greatest impacts will be observed with CT. The study also found significantly more fluometuron in runoff from ST than CT plots. Further work is needed to determine whether this behavior may be generalized to other active ingredients with similar properties [low K(oc) (organic carbon partition coefficient) approximately 100 mL g(-1); high water solubility approximately 100 mg L(-1)]. If so, it should be considered when making tillage-specific herbicide recommendations to reduce runoff potential.     

Hemolysis,Fish Mortality,and LC-ESI-MS of Cultured Crude and Fractionated Golden Alga (Prymnesium parvum)1

Schug, Kevin A., Theodore R. Skingel, Sandra E. Spencer, Carlos A. Serrano, Cuong Q. Le, Christopher A. Schug, Theodore W. Valenti, Jr., Bryan W. Brooks, Laura D. Mydlarz, and James P. Grover, 2010. Hemolysis, Fish Mortality, and LC-ESI-MS of Cultured Crude and Fractionated Golden Alga (Prymnesium parvum). Journal of the American Water Resources Association (JAWRA) 46(1):33-44. DOI: 10.1111/j.1752-1688.2009.00389.x Abstract: Erythrocyte lysis and fish mortality assays, in combination with high performance liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) analysis, were investigated for bioassay-guided fractionation of cultured golden alga (Prymnesium parvum). Intracellular constituents from isolated cell pellets and extracellular supernatant growth medium were fractionated by a variety of common separation modes, including reversed phase and normal phase solid phase extraction step fractionation procedures. For reversed phase fractionation of extracellular growth medium, one fraction was obtained that displayed hemolytic activity and adversely affected fish survival. Effective dose concentrations for this sample were similar in both assays and the LC-ESI-MS analysis of the fraction showed a number of mass spectral signals which were distinct to this fraction. Fractions obtained from separation of an ethanol extract of the lyophilized cell pellet provided one sample that was highly hemolytic, but not toxic to fish. Discrepancies such as this, along with notable fish behavioral responses from other nonhemolytic cell pellet fractions, problems with the use of unbonded silica gel for fractionation, and misleading mass spectral signatures are interesting in the context of our current understanding of P. parvum toxicity and remain to be investigated further. This work provides an account of ongoing research aimed toward comprehensive elucidation of toxic constituents produced by golden alga for the purpose of providing a better understanding and means to potentially remediate the ecological impact of this harmful bloom organism.     

Circulation and Stream Plume Modeling in Conesus Lake

A three-dimensional hydrodynamic model that includes the effect of drag from macrophytes was applied to Conesus Lake to study the seasonal circulation and thermal structure during spring and early summer. Local weather conditions and stream flow data were used to drive the model. The drag coefficient for macrophytes was calculated as a function of leaf density. In general, the model results show good agreements with the observations, including vertical temperature profiles measured at two locations and average surface temperature derived from calibrated thermal imagery for large-scale simulations of the entire lake. Additional high-resolution simulations were carried out to understand water circulation and transport of sediment and model-generated tracer during hydrometeorological events at stream mouths for two experimental sites. The model results show that the plume development at stream mouths during storm events in Conesus Lake are site-dependent and may either be current- or wind-driven. The results also show a significant effect from the presence of macrophytes on sediment deposition near stream mouths.     

Effect of Bag Failure on Baghouse Outlet Loading

One of the most important considerations in baghouse operation is the effect of bag failure on outlet loading. This information would be Of use to equipment manufacturers, users, and regulatory officials. Unfortunately, little information is available in the literature on this aspect of baghouse performance. Equations describing changes in outlet loading resulting from the sudden rupture of one or more bags are developed from first principles. Calculated results from these equations are presented in the form of a chart which can very quickly and simply be used to obtain a numerical value for a revised outlet loading resulting from bag failure(s) for a variety of system conditions. Due to an assumption made in the derivation, the new outlet loading thus obtained represents the maximum increase (worst case conditions) to be expected from the rupture of one or more bags. The following variables are included in the analysis: inlet loading, outlet loading (prior to bag failure), number of bag failures, bag diameter, system pressure drop; and gas temperature.