Electrostatic Dust Collectors Research Articles

Risk factors for persistence of livestock-associated MRSA and environmental exposure in veal calf farmers and their family members: an observational longitudinal study

ObjectivesLivestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) emergence is a major public health concern. This study was aimed at assessing risk factors for persistently carrying MRSA in veal calf farmers and their...

Relationship between Presence of Cows with Milk Positive for Mycobacterium avium subsp. paratuberculosis-Specific Antibody by Enzyme-Linked Immunosorbent Assay and Viable M. avium subsp. paratuberculosis in Dust in Cattle Barns

Paratuberculosis, or Johne's disease, in cattle is caused by Mycobacterium avium subsp. paratuberculosis, which has recently been suspected to be transmitted through dust. This longitudinal study on eight commercial M. avium subsp. paratuberculosis-positive dairy farms studied the relationship between the number of cows with M. avium subsp. paratuberculosis antibody-positive milk and the presence of viable M. avium subsp. paratuberculosis in settled-dust samples, including their temporal relationship. Milk and dust samples were collected in parallel monthly for 2 years. M. avium subsp. paratuberculosis antibodies in milk were measured by enzyme-linked immunosorbent assay (ELISA) and used as a proxy for M. avium subsp. paratuberculosis shedding. Settled-dust samples were collected by using electrostatic dust collectors (EDCs) at six locations in housing for dairy cattle and young stock. The presence of viable M. avium subsp. paratuberculosis was identified by liquid culture and PCR. The results showed a positive relationship (odds ratio [OR], 1.2) between the number of cows with ELISA-positive milk and the odds of having positive EDCs in the same airspace as the adult dairy cattle. Moreover, the total number of lactating cows also showed an OR slightly above 1. This relationship remained the same for settled-dust samples collected up to 2 months before or after the time of milk sampling. The results suggest that removal of adult cows with milk positive for M. avium subsp. paratuberculosis-specific antibody by ELISA might result in a decrease in the presence of viable M. avium subsp. paratuberculosis in dust and therefore in the environment. However, this decrease is likely delayed by several weeks at least. In addition, the data support the notion that M. avium subsp. paratuberculosis exposure of young stock is reduced by separate housing.

Efficiency determination of an electrostatic lunar dust collector by discrete element method

Lunar grains become charged by the sun’s radiation in the tenuous atmosphere of the moon. This leads to lunar dust levitation and particle deposition which often create serious problems in the costly system deployed in lunar exploration. In this study, an electrostatic lunar dust collector (ELDC) is proposed to address the issue and the discrete element method (DEM) is used to investigate the effects of electrical particle-particle interactions, non-uniformity of the electrostatic field, and characteristics of the ELDC. The simulations on 20-μm-sized lunar particles reveal the electrical particle-particle interactions of the dust particles within the ELDC plates require 29% higher electrostatic field strength than that without the interactions for 100% collection efficiency. For the given ELDC geometry, consideration of non-uniformity of the electrostatic field along with electrical interactions between particles on the same ELDC geometry leads to a higher requirement of ∼3.5 kV/m to ensure 100% particle collection. Notably, such an electrostatic field is about 103 times less than required for electrodynamic self-cleaning methods. Finally, it is shown for a “half-size” system that the DEM model predicts greater collection efficiency than the Eulerian-based model at all voltages less than required for 100% efficiency. Halving the ELDC dimensions boosts the particle concentration inside the ELDC, as well as the resulting field strength for a given voltage. Though a lunar photovoltaic system was the subject, the results of this study are useful for evaluation of any system for collecting charged particles in other high vacuum environment using an electrostatic field.

Assessment of airborne exposures and health in flooded homes undergoing renovation.

In June 2008, the Cedar River crested flooding more than 5000 Cedar Rapids homes. Residents whose homes were flooded were invited to participate in this study. Household assessments and resident interviews were conducted between November 2008 and April 2009. We characterized exposures and symptoms experienced by individuals inhabiting 73 flood-damaged homes. Active air sampling and passive electrostatic dust collectors were used to assess exposures to culturable mold, culturable bacteria, fungal spores, inhalable particulate matter (iPM), endotoxin, glucans, allergens, lead, asbestos, radon, carbon dioxide, and carbon monoxide. Wall moisture levels and relative humidity were also measured. Exposures and questionnaire-based health assessments were compared at two levels of remediation, in-progress and completed. Homes with remediation in-progress (N = 24), as compared to the completed homes (N = 49), had significantly higher airborne concentrations of mold, bacteria, iPM, endotoxin, and glucan. Residents of in-progress homes had a significantly higher prevalence of doctor-diagnosed allergies (adjusted OR = 3.08; 95% CI: 1.05, 9.02) and all residents had elevated prevalence of self-reported wheeze (adjusted OR = 3.77; 95% CI: 2.06, 6.92) and prescription medication use for breathing problems (adjusted OR = 1.38; 95% CI: 1.01, 1.88) after the flood as compared to before. Proper post-flood remediation led to improved air quality and lower exposures among residents living in flooded homes. The number and severity of floods is on the rise, and health departments need evidence-based information to advise homeowners on recovery after such disasters. Our study suggests that proper remediation of flood-damaged homes can reduce bioaerosols to acceptable levels but exposures are significantly increased while remediation is in-progress leading to an increased burden of allergy and allergic rhinitis.

Microbiological evaluation of ten French archives and link to occupational symptoms

Fungi that damage documents in archives may harm workers' health, depending on which mold species are inhaled, the concentrations of fungal species inhaled, and individual factors. Our aim was to identify and quantify fungi in archives and to investigate possible links with the symptoms experienced by workers. Ten French archives were sampled using an air impactor and electrostatic dust collectors. Allergies and general symptoms felt by 144 workers were reported using a self-report questionnaire. Utilizing culture-based analysis methods along with qPCR, Penicillium chrysogenum, Cladosporium sphaerospermum, and Aspergillus versicolor were the three main fungi in air and dust in terms of quantity and frequency. Median fungal concentrations in storage areas, ranged from 30 to 465 CFU/m(3). People working in the most contaminated archives did not report more symptoms of allergy than others. However, workers in contact with moldy documents reported more headaches (odds ratio, 2.4; 95% confidence interval, 1.1-5.3), fatigue (OR, 2.9; 95% CI, 1.2-6.7), eye irritation (OR, 5.4; 95% CI, 1.9-14.9), throat irritation (OR, 2.4; 95% CI, 1.0-5.7), coughing (OR, 3.2; 95% CI, 1.2-8.4), and rhinorrhea (OR, 2.6; 95% CI, 1.0-6.4) than others. Other parameters such as dust levels and concentrations of metabolites and chemical substances should be considered as confounding factors in further investigations to isolate the role of molds. Most studies about fungi and archives deal with the conservation of manuscripts and documents, and few discuss workers' health problems. Our study shows that archives do not represent a highly contaminated environment. Symptoms felt by workers were more often linked to direct contact with moldy documents than to high concentrations of mold in the air of archive storage areas. This study provides data on concentration levels in archives that could be used to interpret microbiological investigations in this type of environment in the future.

Theoretical aspects of an electrostatic aerosol filter for civilian turbofan engines

The paper addresses the problem of aerosol filtration in turbofan engines. The current problem of very fine aerosol admission is the impossibility for mechanical filtration; another aspect of the problem is the high mass flow of air to be filtered. Non-attended, the aerosol admission can -and usually does- lead to clogging of turbine cooling passages and can damage the engine completely. The approach is theoretical and relies on the principles of electrostatic dust collectors known in other industries. An estimative equation is deduced in order to quantify the electrical charge required to obtain the desired filtration. Although the device still needs more theoretical and experimental work, it could one day be used as a means of increasing the safety of airplanes passing trough an aerosol laden mass of air.

Electrostatic particle collection in vacuum

Lunar grains accumulate charges due to solar-based ionizing radiations, and the repelling action of like-charged particles causes the levitation of lunar dust. The lunar dust deposit on sensitive and costly surfaces of investigative equipment is a serious concern in lunar explorations. Inspired by electrostatic precipitators (ESPs), the Electrostatic Lunar Dust Collector (ELDC) was proposed for collecting already charged lunar dust particles to prevent the lunar dust threat. As the conditions for terrestrial counterparts are not valid in the lunar environment, equations developed for terrestrial devices yield incorrect predictions in lunar application. Hence, a mathematical model was developed for the ELDC operating in vacuum to determine its collection efficiency. The ratios of electrical energy over potential energy, kinetic energy over potential energy and the ratio of ELDC dimensions were identified to be the key dimensionless parameters. Sensitivity analyses of the relevant parameters showed that depending on ELDC orientation, smaller particles would be collected more easily at vertical orientation, whereas larger particles were easier to collect in a horizontal ELDC configuration. In the worst case scenario, the electrostatic field needed to be 10 times stronger in the vertical mode in order to adequately collect larger particles. The collection efficiency was very sensitive to surface potential of lunar dust and it reached the maximum when surface potential was between 30 and 120 V. Except for regions of the lunar day side with surface potential close to zero, providing 1 kV ( E = 20 kV m −1) with the ELDC was more than enough for collecting all the particles in the most critical orientation. The needed field strength was about 4000 times less than that for repelling 1-μm size particles already settled on the surfaces. The analysis shows that the ELDC offers a viable solution for lunar dust control due to its effectiveness, ease of cleaning and low voltage requirements.

The Emission and Distribution of PCDD/Fs in Municipal Solid Waste Incinerators and Coal-fired Power Plant

The emission and distribution of polychlorinated debenzo-p-dioxins/dibenzofurans (PCDD/Fs) was investigated in two municipal solid waste incinerators (MSWIs) and one coal-fired power plant (PP) in southern Taiwan. Samples were collected from stack flue gases (SFG), bottom residues (BR), super heater (SH), economizer (EC), semi-dry absorber (SDA), bag filter (BF), and fly ash pit (FAP) in MSWIs. Stack flue gases, bottom residues and electrostatic dust collectors (ESD) in PP were also collected. In order to compare the difference between the results of MSWIs and PP, samples from SFG, BS, and FAP in a PP were also determined. Seventeen congeners of PCDD/Fs were analyzed by utilizing a high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS). Distributions of total PCDD/F-I-TEQ in each unit of MSWI-A and MSWI-B were SFG (0.3%, 0.07%), BR (3.9%, 0.62%), SH (0.17%, 0.24%), EC (4.2%, 0.05%), SDA (1.29%, 7.06%), and BF (90.14%, 91.97%), respectively. However, those in SFG, BS, and FAP of PP were 99.58%, 0.17%, and 0.25%, respectively. The above results indicated 99.5% PCDD/Fs were trapped in the fly ash of MWSI. On the other hand, 99.7% PCDD/Fs was emitted to the atmosphere from PP. The results of this study provide useful information for controlling PCDD/Fs in MSWIs and PP.

Handbook of separation techniques for chemical engineers

Continuous distillation - separation of binary mixtures continuous distillation - separation of multi-component mixtures batch distillation steam distillation/stripping design of tray columns solvent recovery air stripping liquid-liquid extraction commercial liquid-liquid extraction decantation ion exchange separations activated carbon systems for separations of liquid dialysis and electodialysisi parametrc pumping high-pressure liquid chromatographic separations commercial coalescers membrane filtration evaporation crystallization from solutions foam separation processes gas phase absorption design of gas absorption towers mass transfer using fuidized bed techniques filtration theory flter-aid filtration batch filtration continuous filtration centrifugation cartridge filtration felt stainer bags sedimantation hydroclone separation drying of wet solids and solids in liquid leaching flotation melt crystallization solid-solid separations gas-solid separations electrostatic precipitators dust collectors, application and design and air separartion barrier filtration of hot gas.

Observations of dust trapping phenomena in the TRISTAN accumulation ring and a study of dust removal in a beam chamber

Using a gamma-ray detector and a television camera system for synchrotron light, high-energy bremsstrahlung and horizontal growth of the synchrotron light source were observed when sudden decrease in the electron-beam lifetime occurred due to dust trapping in the electron beam. Two types of beam current losses were found; one was a continuous beam current loss, and the other was a short-term beam current loss. High-energy bremsstrahlung at a location was observed in a short time and after that, the bremsstrahlung was not detected in spite of the occurrence of dust trapping phenomena. The fact suggests motions of the trapped dust particles in the longitudinal directions. Materials collected in the beam chamber are dust particles from ion pumps and dust particles made during the beam chamber processing for welding. Most of the collected dust particles were less than 2 mm in size and surfaces of some dust particles were melted with the electron beam. Simple analysis was carried out for the conditions necessary for a dust particle to be trapped, for motions of the trapped dust particle, and for interactions between the trapped dust particle and the electron beam. The analysis showed that a dust particle less than 3 mm in size, made of Al, can be trapped and that the trapped dust particle can move in the vertical and longitudinal directions. The analysis also suggested that a dust particle in size of about 2 mm can be continuously trapped around the electron beam without being destroyed by the electron beam. Furthermore, the analysis explained the difference between the two types of beam current losses observed in the ring. Experiments which simulate the electron beam using a Cu wire in an evacuated beam chamber show that a dust particle (less than 70 μm) is trapped sufficiently. The experiments also coincide with theory for an attractive force acting to a conducting small particle. The calculated electric field of the electron beam and the calculated electric charge of dust particles given through the photoelectric effect in the TRISTAN accumulation ring are 100 times and 104–106 times higher than those of the simulated experiments, respectively. In the ring, the attractive force caused with the average electric field and with the expected charge is 10–103 times larger than that of the simulated experiments. Therefore, a dust particle (less than 2 mm) can be trapped sufficiently. An electrostatic dust collector using an electron beam and an electrostatic force are effective in removing all of the sample dust particles in the test chamber for the simulated experiments. A method to remove trapped dust particles using electrostatic electrodes is also discussed. It is expected that such electrodes can be useful for trapped dust particles moving in a longitudinal direction.

New electrostatic dust collector for use in vacuum systems

A new active dust collector was developed for use in vacuum systems. The dust is collected using an electrostatic force only or using an electron beam. The dust collecting electrode is made from copper-clad fiberglass epoxy. The potential of the electrode can be varied from −3 to +3 kV. The current of the electron beam was 14 μA, and the vacuum pressure in the test chamber ranged from 10−6 to 10−7 Torr. The dust collecting device was tested with several conducting and nonconducting dust materials ∼60 μm in size on substrate materials of stainless steel, Al, Cu, Si wafers, and quartz. Dust removal was monitored using an optical microscope with a video camera. The results show that the new active dust collector removes 90% or more of the dust materials from most substrates.

真空静電集塵装置

真空静電集塵装置

Influence of shapes of corona electrodes on density of emission currents in electrostatic dust collectors

The present work describes an analysis of the influence of the edge profile on the density of emission current in conditions of electrical corona on a laboratory scale. The current-voltage characteristics of a discharge chamber for several types of discharge electrodes are presented. Special attention has been paid to various arrangements of tape electrodes: namely a tape electrode with pointed edges or spikes, tape electrodes without spikes and tape electrodes with knife edges.