Elimination of VOC Emissions from Surface Coating Operations

Collectively, surface coating operations using paints with hydrocarbon solvents may well be the largest industrial source of volatile organic compounds (VOC) and hazardous air pollutants (HAP). Most surface coating operations involve the manual application of paint with spray equipment inside a paint spray booth. The booth exhaust system collects the solvent fumes and then exhausts them through a stack to the atmosphere. Stack emissions are characteristically high in flow rate and low in concentration. Since control equipment is sized based on exhaust flow rate rather than concentration, control of VOC and HAP requires large, expansive abatement equipment. Simple, effective designs employing recycling of air have greatly reduced the exhaust flow rate and the cost of the control equipment. However, these designs are not popular because they are burdened by various flaws, notably worker endangerment. The Mobile Zone recirculation system can be incorporated into new construction or retrofitted to existing spray booths and will reduce the exhaust volumes ranging from 65 to 95 percent without adversely affecting the production rate, production quality or worker safety.     

A Statistical Model for FEV1 Response to Arbitrary Dynamic Ozone Exposure Conditions

ABSTRACT

Lung function response to inhaled ozone at ambient air pollution levels is known to be a function of ozone concentration, exposure duration, and minute ventilation. Most data-driven exposure-response models address exposures under static condition (i.e., with a constant ozone concentration and exercise pattern). Such models are simplifications, as both ambient ozone concentrations and normal human activity patterns change with time. The purpose of this study was to develop a dynamic model of response with the advantages of a statistical model (a relatively simple structure with few parameters). A previously proposed mechanistic model for changes in specific airways resistance was adapted to describe the percent change in forced expiratory volume in one second (FEV₁). This model was then reduced using the fit to three existing exposure-response data sets as criterion. The resulting model consists of a single linear differential equation together with an algebraic logistic equation. Under restricted static conditions the model reduces to a logistic model presented earlier by the authors.     

Quantitative assessment of medical waste generation in the capital city of Bangladesh

There is a concern that mismanagement of medical waste in developing countries may be a significant risk factor for disease transmission. Quantitative estimation of medical waste generation is needed to estimate the potential risk and as a basis for any waste management plan. Dhaka City, the capital of Bangladesh, is an example of a major city in a developing country where there has been no rigorous estimation of medical waste generation based upon a thorough scientific study. These estimates were obtained by stringent weighing of waste in a carefully chosen, representative, sample of HCEs, including non-residential diagnostic centres. This study used a statistically designed sampling of waste generation in a broad range of Health Care Establishments (HCEs) to indicate that the amount of waste produced in Dhaka can be estimated to be 37 ± 5 ton per day. The proportion of this waste that would be classified as hazardous waste by World Health Organisation (WHO) guidelines was found to be approximately 21%. The amount of waste, and the proportion of hazardous waste, was found to vary significantly with the size and type of HCE.     

Comparison of the SCAQS Tunnel Study with Other On Road Vehicle Emission Data

The Van Nuys Tunnel experiment conducted in 1987 by Ingalls et al. (see A&WMA Paper 89-137.3), to verify automotive emission inventories as part of the Southern California Air Quality Study (SCAQS), gave higher CO and HC emission-rate values than expected on the basis of automotive-emission models—by factors of approximately 3 and 4, respectively. The CO/NO_X and HC/NO_X emission-rate ratios moreover were higher than expected—by similar factors (NO_X emission rates were about as expected). The purpose of the present paper is to review the literature on dynamometer and on-road (in tunnels and along roadways) testing of in-use vehicles, and on urban-air CO/HC/NO_X concentration ratios, to see whether the Van Nuys Tunnel results are reasonable in terms of previous experience. The conclusions are that (1) on-road CO and HC emissions higher than expected have been reported before, (2) on-road CO and HC emissions consistent with the Van Nuys Tunnel results have been reported before, and (3) on-road CO/NO_X and HC/NO_X emission-rate ratios higher than expected have been reported before. The Van Nuys Tunnel NO_X results actually are lower than in other on-road experiments, and the CO/NO_X and HC/NO_X ratios consequently are higher. The higher-than-predicted CO/NO_X and HC/NO_X ratios at Van Nuys and other on-road sites suggest richer operation on-road than predicted or than observed in the inuse- vehicle dynamometer tests which serve as the model inputs. Support for these suggestions and conclusions is found in comparison of urban-air and emission-inventory HC/NO_X ratios.     

Evaluation of the RAMS Continuous Monitor for Determination of PM2.5 Mass Including Semi-Volatile Material in Philadelphia,PA

Abstract

The real-time ambient mass sampler (RAMS) is a continuous monitor based on particle concentrator, denuder, drier, and tapered element oscillating microbalance (TEOM) monitor technology. It is designed to measure PM_2.5 mass, including the semi-volatile species NH₄NO₃ and semi-volatile organic material, but not to measure PM_2.5 water content. The performance of the RAMS in an urban environment with high humidity was evaluated during the July 1999 NARSTO-Northeast Oxidant and Particles Study (NEOPS) intensive study at the Baxter water treatment plant in Philadelphia, PA. The results obtained with the RAMS were compared to mass measurements made with a TEOM monitor and to constructed mass obtained with a Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS) sampler designed to determine the chemical composition of fine particles, including the semi-volatile species. An average of 28% of the fine particulate material present during the study was semi-volatile organic material lost from a filter during particle collection, and 1% was NH₄NO₃ that was also lost from the particles during sampling. The remaining mass was dominantly nonvolatile (NH₄)₂SO₄ (31%) and organic material (37%), with minor amounts of soot, crustal material, and nonvolatile NH₄NO₃. Comparison of the RAMS and PC-BOSS results indicated that the RAMS correctly monitored for fine particulate mass, including the semi-volatile material. In contrast, the heated filter of the TEOM monitor did not measure the semi-volatile material. The comparison of the RAMS and PC-BOSS data had a precision of ±4.1 μg/m³ (±9.6%). The precision of the RAMS data was limited by the uncertainty in the blank correction for the reversible adsorption of water by the charcoal-impregnated cellulose sorbent filter of the RAMS monitor. The precision of the measurement of fine par-ticulate components by the PC-BOSS was ±6-8%.     

Overfill protective systems – Complex problem,simple solution

Overfills have resulted in significant process safety incidents. Longford (Australia, 1998), Texas City (United States, 2005), and Buncefield (United Kingdom, 2005) can be traced to loss of level control leading to high level and ultimately to loss of containment. A tower at Longford and a fractionating column at Texas City were overfilled, allowing liquid to pass to downstream equipment that was not designed to receive it. The Buncefield incident occurred when a terminal tank was overfilled releasing hydrocarbons through its conservation vents.The causes of overfill are easy to identify; however, the risk analysis is complicated by the combination of manual and automated actions often necessary to control level and to respond to abnormal level events. This paper provides a brief summary of the Longford, Texas City, and Buncefield incidents from an overfill perspective and highlights 5 common factors that contributed to making these incidents possible. Fortunately, while overfill can be a complex problem, the risk reduction strategy is surprisingly simple.     

The role of learning in sustainable communities of practice

This paper adds to the literature on skills for sustainable communities by examining the role and processes of learning in “communities of practice” that exist within a “grassroots association”. Interviews were conducted with participants in the communities of practice of a student group called Green Action, which engages with environmental issues in practical ways. The findings demonstrate how learning occurred in the communities of practice, how participants gained skills and knowledge for sustainable consumption, and how learning in the communities of practice appeared to help Green Action to sustain itself in the long-term. This paper could serve as a useful demonstration to others as to how to apply the theories and concepts from the literature on communities of practice when researching skills and knowledge for sustainable communities. It also has some value for grassroots associations themselves in understanding their own activities.     

A Comparison of Bayesian Methods for Uncertainty Analysis in Hydraulic and Hydrodynamic Modeling

We evaluate and compare the performance of Bayesian Monte Carlo (BMC), Markov chain Monte Carlo (MCMC), and the Generalized Likelihood Uncertainty Estimation (GLUE) for uncertainty analysis in hydraulic and hydrodynamic modeling (HHM) studies. The methods are evaluated in a synthetic 1D wave routing exercise based on the diffusion wave model, and in a multidimensional hydrodynamic study based on the Environmental Fluid Dynamics Code to simulate estuarine circulation processes in Weeks Bay, Alabama. Results show that BMC and MCMC provide similar estimates of uncertainty. The posterior parameter densities computed by both methods are highly consistent, as well as the calibrated parameter estimates and uncertainty bounds. Although some studies suggest that MCMC is more efficient than BMC, our results did not show a clear difference between the performance of the two methods. This seems to be due to the low number of model parameters typically involved in HHM studies, and the use of the same likelihood function. In fact, for these studies, the implementation of BMC results simpler and provides similar results to MCMC. The results of GLUE are, on the other hand, less consistent to the results of BMC and MCMC in both applications. The posterior probability densities tend to be flat and similar to the uniform priors, which can result in calibrated parameter estimates centered in the parametric space.     

Emotional labor threatens decent work: A proposal to eradicate emotional display rules

Emotional labor—the management of emotional displays as part of one's work role—has emerged as a growth area of study within organizational behavior and customer service research. In this article, we call attention to the human costs of “service with a smile” requirements with little benefits. We first review the evidence showing that requiring positive emotions from employees induces dissonance and depleted resources, which hinders task performance and threatens well‐being. We articulate how formalized emotion display requirements limit self‐determination by threatening the autonomy, competence, and belongingness needs of employees. Further, via an organizational justice lens, we argue that emotional labor is an unfair labor practice because employees in such circumstances are (1) undervalued by the organization (constituting distributive injustice); (2) disrespected by customers (constituting interactional injustice); and (3) self‐undermined by organizational policies (constituting procedural injustice). We then argue for bringing light to the dark side of emotional labor with a “modest proposal”: Organizations and customers should abandon formalized emotion display expectations and replace such efforts with more humanistic practices that support and value employees, engendering positive climates and an authentically positive workforce. Copyright © 2015 John Wiley & Sons, Ltd.