Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part III. Testing at a Higher Scale and Assessment of Selected Potential Operational Issues.

The feasibility of lime sludge utilization for flue gas desulfurization was evaluated by continuing the previous laboratory-scale studies at a higher scale and investigating two potential operational issues, namely viscosity and metal corrosion. Two lime sludge samples and a baseline limestone sample, which were previously characterized and tested for SO2 capture from a simulated flue gas at a laboratory scale, were first tested at a 10-fold scale with a simulated flue gas, and then tested with a slipstream of flue gas from a coal-fired power plant. The tested lime sludge and limestone slurries reduced the SO2 concentration of the simulated flue gas from 2000 to <1 ppm, and they demonstrated similar Hg reemission profiles. Field-testing results revealed that the limestone and lime sludge slurries reduced the SO2 concentration of the flue gas from ~1500 to <1 ppm. These experiments confirmed our previous smaller scale laboratory results that lime sludge can function as a suitable substitute for limestone for SO2 removal from the flue gas of coal-fired power plants without negatively affecting Hg reemission. Two operational issues, namely viscosity and metal corrosion, were investigated to evaluate practical issues in the transition from limestone to lime sludge at power plants. Results of Marsh funnel viscosity experiments conducted at different solids contents and temperatures indicated the limestone and lime sludge slurries and their gypsum counterparts had similar flow characteristics. Carbon-steel, stainless-steel, and Hastelloy coupons were tested for corrosion by lime sludge and limestone slurries. Both stainless steel and Hastelloy were resistive to corrosion in slurries made from lime sludge or limestone samples or their gypsum counterparts. A considerable but similar amount of corrosion was observed for carbon-steel coupons exposed to lime sludge and limestone slurries. Adding 5000 ppm of Cl- to slurries considerably increased the corrosion rate of carbon steel.

Removal of Stabilized Silver Nanoparticles from Surface Water by Conventional Treatment Processes.

Engineered nanomaterials are used in many applications, including pollution sensors, photovoltaics, medical imaging, drug delivery and environmental remediation. Due to their numerous applications, silver nanoparticles (Ag NPs) are receiving a large amount of attention. Ag NPs may occur in drinking water sources either during manufacturing, consumption and/or disposal processes. This potentially leads to the presence of Ag NPs in finished drinking water, which could have public health impacts. The objective of this research was to investigate the removal of several types of stabilized Ag NPs by potable water treatment processes. Specifically, this research achieved these objectives through; 1) Synthesis of Citrate-reduced Ag NPs, Polyvinylpyrrolidone stabilized (PVP) Ag NPs and Branched polyethyleneimine stabilized (BPEI) Ag NPs, 2) Characterization of synthesized Ag NPs to determine their aggregation potential, Zeta potential profiles, (pHpzc) and obtain morphological data from SEM images, and 3) An evaluation of the efficacy of conventional water treatment processes (i.e., coagulation, flocculation, sedimentation and sand filtration) in removing stabilized Ag NPs from natural water. The three NPs were found to be stable at the nano size in natural water. Alum coagulation had no impact on the PVP and BPEI Ag NPs. Flocculation and settling were found to be key steps for removal of these NPs. The three Ag NPs were not permanently removed by means of conventional water treatment processes employed in this study.

Effectiveness of point-of-use/point-of-entry systems to remove per- and polyfluoroalkyl substances from drinking water.

The contamination of groundwater sources with per- and polyfluoroalkyl substances (PFAS) in the United States is a widespread problem for the drinking water industry. Well water supplies in the municipalities of Fountain, Security, and Widefield, Colorado, contain perfluorooctanoic acid and perfluorooctane sulfonate levels greater than the U.S. Environmental Protection Agency (USEPA) health advisory level of 70 ng/L. The source of PFAS has been associated with aqueous film-forming foam at Peterson Air Force Base. To assist property owners and limit the exposure of PFAS to residential drinking water systems, treatability studies were conducted by the USEPA on the PFAS removal effectiveness of commercially available point-of-use/point-of-entry units using reverse osmosis treatment and granular activated carbon adsorbents. Household water systems were tested with a test water containing the water quality characteristics and six PFAS contaminants found in Widefield aquifer region groundwater samples. This study also documents the installation, startup, and continuous/intermittent operation of the treatment systems.

Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part I. Supply-Demand Evaluation and Life Cycle Assessment.

The feasibility of lime-softening sludge utilization for flue gas desulfurization in coal-fired power plants was evaluated through a supply-demand analysis and a life cycle assessment (LCA). To evaluate the demand and supply of lime sludge to replace limestone on a national scale, the annual amount of lime sludge generated by water treatment utilities in the United States was estimated and compared with the annual amount of limestone used by coal-fired power utilities. To evaluate the environmental sustainability of reusing lime sludge in power plants, an LCA study was performed in which the environmental impact and water footprint of the proposed approach were quantified and these results were compared with the conventional approaches for limestone mining, grinding, and transportation to power plants and lime sludge disposal in landfills. Water utilities across the United States are currently generating approximately 3.2 million tons of lime sludge per year at an estimated disposal cost of approximately US$90 million, whereas power utilities are using approximately 6.3 million tons of limestone per year. The potential savings that would result from partial replacement of limestone with lime sludge was estimated to be approximately US$97 million per year. The LCA study showed that the environmental impact of lime sludge utilization in power plants under different scenarios was 2 orders of magnitude lower than that of the landfill disposal option. Furthermore, the water footprint for lime sludge reuse in power plants was almost negligible compared with that of the conventional approaches of disposing of lime sludge at water utilities or using limestone at power utilities.

Utilization of Water Utility Lime Sludge for Flue Gas Desulfurization in Coal-Fired Power Plants: Part II. Lime Sludge Characterization and Mercury Reemission.

The feasibility of utilizing lime sludge in the flue gas desulfurization process of coal-fired power plants was evaluated through laboratory-scale studies. Eight lime sludge samples, collected from various water treatment plants, and a high-purity limestone sample were extensively characterized and tested for their ability to capture SO2 from a simulated flue gas, while investigating the mercury reemission profiles during the scrubbing process. The reactivity of lime sludge samples for acid neutralization was significantly higher than the reactivity of the tested limestone sample. At doses less than that of the limestone sample, the lime sludge materials reduced the SO2 concentration from 2,000 to <0.5 ppm. The residual lime, higher surface area, and more accessible pores in lime sludge samples were the major factors contributing to their higher reactivity. Concentrations of several elements including B, Mg, Mn, Fe, Cu, Zn, As, Sr, and Ba in some of the tested lime sludge samples were considerably higher than those elements in the limestone. However, no significant leaching of these elements into the scrubber solutions was observed. To investigate mercury reemission during the scrubbing process, ionic mercury was introduced into the simulated slurry and mercury reemission was monitored continuously. Results showed that compared with the limestone sample, the lime sludge samples tested had lower or similar cumulative mercury reemissions. However, different lime sludge samples showed different emission profiles. No conclusive correlation between the composition or trace element content of lime sludge samples and their mercury reemission could be identified. This result was likely due to the oxidative condition of the scrubbing process, which prohibited the reducing species from transforming the ionic mercury into elemental mercury.

Examining the efficiency of muffle furnace-induced alkaline hydrolysis in determining the titanium content of environmental samples containing engineered titanium dioxide particles.

A novel muffle furnace (MF)-based potassium hydroxide (KOH) fusion digestion technique was developed and evaluated for different titanium dioxide materials in various solid matrices. Digestion of different environmental samples containing sediments, clay minerals and humic acid with and without TiO(2) particles was first performed utilizing the MF-based KOH fusion technique and its dissolution efficacy was compared to a Bunsen burner (BB)-based KOH fusion method. The three types of TiO(2) particles (anatase, brookite and rutile) were then digested with the KOH fusion techniques and microwave (MW)-based nitric (HNO3)­hydrofluoric (HF) mixed acid digestion methods. Statistical analysis of the results revealed that Ti recoveries were comparable for the KOH fusion methods (BB and MF). For pure TiO(2) particles, the measured Ti recoveries compared to calculated values were 96%, 85% and 87% for anatase, brookite and rutile TiO(2) materials, respectively, by the MF-based fusion technique. These recoveries were consistent and less variable than the BB-based fusion technique recoveries of 104%, 97% and 72% and MW-based HNO3­HF mixed acids digestion recoveries of 80%, 81% and 14%, respectively, for anatase, brookite and rutile. Ti percent recoveries and measurement precision decreased for both the BB and MF methods when TiO(2) was spiked into sediment, clay minerals, and humic acid. This drop in efficacy was counteracted by more thorough homogenization of the spiked mixtures and by increasing the mass of KOH in the MF fusion process from 1.6 g to 10.0 g. The MF-based fusion technique is consistently superior in digestion efficiency for all three TiO(2) polymorphs. The MF-based fusion technique required 20 minutes for digestion of 25 samples (based on in-house Lindberg MF capacity) compared to 8 hours for the same number of samples using the BB-based fusion technique. Thus, the MF-based fusion technique can be used to dissolve a large number of samples in a shorter time (e.g., 500 samples per 8 hours) while conserving energy and eliminating health and safety risks from methods involving HF.

Inhaled fluticasone propionate impairs pulmonary clearance of Klebsiella pneumoniae in mice.

BACKGROUND: Recent trials demonstrate increased pneumonia risk in chronic obstructive pulmonary disease patients treated with the inhaled corticosteroid (ICS) fluticasone propionate (FP). There is limited work describing FP effects on host defenses against bacterial pneumonia. METHODS: C57BL/6 mice received daily, nose-only exposure to nebulized FP or vehicle for 8 days, followed by pulmonary challenge with Klebsiella pneumoniae. Bacterial burden, phagocytosis, leukocyte recruitment, cytokine expression, nitric oxide release, and survival were measured. RESULTS: Inhaled FP increased bacterial burden in lungs and blood 48 h after infection but affected neither in vivo phagocytosis of bacteria by alveolar macrophages (AM) nor alveolar neutrophil recruitment. AM from FP-treated mice showed impaired expression of infection induced TNF-alpha, IP-10 (CXCL-10), and interleukin 6 (IL-6), and AM also showed a trend towards impaired intracellular pathogen control following in vivo infection. In vitro FP treatment resulted in a dose-dependent impairment of cytokine expression by AM. Furthermore, infection-induced nitric oxide (but not hydrogen peroxide) production was impaired by FP in vivo and in vitro. FP decreased survival in this model. CONCLUSIONS: Exposure to inhaled FP impairs pulmonary clearance of K. pneumoniae in mice, an effect associated with greater systemic bacteremia and death. Decreased AM cytokine and nitric oxide expression parallel the failure to control infection. These results support the study of ICS effects on human pulmonary host defenses.

The fate and transport of the SiO2 nanoparticles in a granular activated carbon bed and their impact on the removal of VOCs.

Adsorption isotherm, adsorption kinetics and column breakthrough experiments evaluating trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) were conducted in the presence and absence of silica nanoparticles (SiO(2) NPs). Zeta potentials of the SiO(2) NPs and the GAC were measured. Particle size distribution (PSD) of SiO(2) NPs dispersions was analyzed with time to evaluate the extent of aggregation. TEM analysis was conducted. The specific surface area and the pore size distribution of the virgin and the spent GAC were obtained. The fate and transport of the SiO(2) NPs in the GAC fixed bed and their impact on TCE adsorption were found to be a function of their zeta potential, concentration and PSD. The interaction of the SiO(2) NPs and the GAC is of an electrokinetic nature. A weak electrostatic attraction was observed between the SiO(2) NPs and the GAC. This attraction favors SiO(2) NPs attachment on the surface of GAC. SiO(2) NPs attachment onto GAC is manifested by a reduction in the amount of TCE adsorbed during the column breakthrough experiments suggesting a preloading pore blockage phenomenon. However, no effect of SiO(2) NPs was observed on the isotherm and the kinetic studies, this is mainly due to the fast kinetics of TCE adsorption.

Evaluating a composite cartridge for small system drinking water treatment.

A pilot-scale evaluation was conducted at the U.S. Environmental Protection Agency (EPA) Test & Evaluation (T&E) Facility in Cincinnati, Ohio, on a multi-layer, cartridge-based system that combines physical filtration with carbon adsorption and ultraviolet (UV) light disinfection to serve as a home-base water treatment security device against accidental or intentional contaminant events. The system was challenged with different levels of turbidity, a number of biological contaminants including Bacillus subtilis, Escherichia coli, MS2 bacteriophage and Polystyrene Latex (PSL) beads as a surrogate for Cryptosporidium and a number of chemical contaminants including super-chlorination, methyl tertiary butyl ether (MTBE), water chlorination disinfection byproducts (DBPs) and diazinon. The results demonstrated that the performance of the system varies as a function of the specific contaminant or surrogate. The overall performance indicated the potential of the system to improve the quality and safety of household water and to serve as an additional treatment barrier in circumstances where there is little or no treatment or where the quality of treated water may have deteriorated during distribution. The results also demonstrated that B. subtilis spore can serve as a more conservative surrogate for Cryptosporidium than PSL beads.

Influences on the prescribing of new drugs.

BACKGROUND: The aim of this study was to identify the factors that influence prescribing of new drugs among general practitioners, endocrinologists and psychiatrists. METHODS: Four focus groups were conducted with GPs, endocrinologists and psychiatrists on sources of awareness and influences on prescribing of new drugs. RESULTS: Pharmaceutical companies were the most important source for becoming aware of new drugs. There were many influences on the decision to prescribe a new drug, the most important being efficacy, safety, cost and advantage over existing therapies. Endocrinologists placed greater emphasis on evidence from clinical trials and scientific conferences, and psychiatrists and GPs placed more weight on pharmaceutical representatives, colleagues and specialists. DISCUSSION: New drug prescribing occurs in a complex environment with many influences. Effective interventions to promote rational, safe and effective prescribing of new drugs will need to be cognisant of these factors.

Evaluating the impact of educational interventions on use of antithrombotics in Australia.

PURPOSE: The National Prescribing Service (NPS) aims to improve prescribing and use of medicines consistent with evidence-based best practice. In particular, specific educational programmes were commenced in 2003 to improve general practitioner (GP) prescribing of antithrombotics. This report assesses the impact of these multiple educational interventions in terms of changes in prescribing rates. METHODS: Monthly prescribing data (July 1996-December 2005) were obtained from a national claims database, and yearly data (2001-2006) from a GP-patient encounter database. The target group was all GPs in Australia and interventions were active (voluntary) and passive (mail-outs). Responses to the interventions were measured by changes in the mean number of antithrombotic prescriptions (for ticlopidine, clopidogrel, warfarin and dipyridamole) per 1000 consultations for each GP each month. These data were analysed using seasonally adjusted piecewise linear dynamic regression. The data from the GP-patient encounter database were reported as mean prescribing rates per 100 GP encounters. RESULTS: NPS interventions either had an effect in the expected direction or had no discernable impact. Prescribing appeared to have decreased for dipyridamole, clopidogrel and ticlopidine, although the decline was only statistically significant for dipyridamole. Prescribing of warfarin continued to rise steadily despite NPS efforts. CONCLUSIONS: The NPS antithrombotics programme appears to have had modest success, but such evaluations raise questions about whether a focus on outcomes at a national level is appropriate, given likely concealment of effects at local levels. Lessons learned should be applied in the evaluation of other programmes aimed at influencing prescribing.

Expanding a professional dental care system: experiences of Task Force 261 Multifunctional Medical Battalion during Operation Iraqi Freedom 07-09.

During Operation Iraqi Freedom 07-09, Task Force 261 Multifunctional Medical Battalion managed an extensive dental care system stretching throughout the Iraq theater of operations. We illustrate several of the unique challenges faced by Task Force 261's headquarters and its dental and area support companies, and describe the remedies emplaced by the Task Force. Personnel structure, the evacuation chain, supply and facility management, dental civil-military operations, detainee care, information technology applications, and public health initiatives are discussed in detail.

Remediation of MTBE from drinking water: air stripping followed by off-gas adsorption.

The widespread use of methyl tertiary butyl ether (MTBE) as an oxygenate in gasoline has resulted in the contamination of a large number of ground and surface water sources. Even though air stripping has been proven to be an effective treatment technology for MTBE removal, off-gas treatment often is required in conjunction with it. This study evaluated the combined treatment technologies of air stripping followed by off-gas adsorption on a pilot scale for the treatment of MTBE-contaminated water. The effect of air/water ratios on the treatment efficiency was studied, and the mass transfer coefficient was determined. Air/water ratios of 105:1, 151:1, 177:1, 190:1, 202:1, and 206:1 were used, and a treatment efficiency of >99% was achieved for all the runs conducted. The depth of packing required to achieve maximum treatment efficiency decreased with increasing air/water ratio. Relative humidity (RH) impacts on the MTBE adsorption capacity of a granular activated carbon (GAC) and carbonaceous resin were determined from pilot plant studies. Breakthrough profiles obtained from the pilot plant studies conducted at 20, 30, and 50% RH indicated that GAC has a higher adsorptive capacity than resin. The adsorptive capacity of GAC decreased with increasing RH, whereas RH did not impact the resin adsorptive capacity.

Antibiotic prescribing for upper respiratory-tract infections in primary care.

The use and overuse of antibiotics in humans is a major contributor to the selection of antibiotic resistance organisms. Recent evidence has shown that primary care prescribing selects for resistances of clinical importance. The National Prescribing Service runs both educational and audit activities. The latter provide some insight into general practice attitudes toward antibiotic prescribing.

Exercise electrocardiography.

Treadmill exercise electrocardiography is a test commonly employed to diagnose coronary artery disease and has powerful prognostic value. It is most accurate when the resting ECG is normal, and because of significant limitations in sensitivity and specificity, the test is most useful when the pretest probability of disease is in the intermediate range. The usual criterion for diagnosing myocardial ischemia is horizontal or downsloping ST-segment depression that measures > or = 1 mm (0.1 mv) 0.08 seconds after the J point, and the specificity of this finding is greatly enhanced by the patient's developing typical angina during the test. Sensitivity and/or specificity may be improved by modifications of the ECG-lead system, computer-assisted measurement of more complex exercise-test variables, using test scores that incorporate coronary risk factors, and by adding radionuclide or echocardiographic imaging modalities that assess myocardial perfusion and/or the metabolic or contractile consequence of myocardial ischemia, as well as the electrocardiographic and symptomatic ones.