Design and Collection Efficiency of a New Electrostatic Precipitator for Bioaerosol Collection

Abstract

We have developed and tested a new bioaerosol sampler in which airborne microorganisms are collected by electrostatic means. In this sampler, 2 ionizers charge the incoming particles if they carry insuf cient electric charge for ef cient collection. The organisms are then subjected to a precipitating electric eld and are collected onto 2 square agar plates positioned along the ow axis. Tests with nonbiological NaCl particles versus B. subtilis var. niger (BG) spores and vegetative cells have shown that airborne microorganisms are collected more ef ciently than nonbiological particles, even when the microorganisms have rst passed through an electric charge neutralizer with no additional charging applied. The difference was attributed to the natural charges contained in cell membranes or spore coats of the microorganisms. Charge-neutralized BG spores and vegetative cells were collected at 4 L/min with efciencies close to 80%, depending on the precipitation voltage, versus 50-60% for NaCl test particles. When incoming BG spores were charged with positive ions and then collected by a precipitating voltage of + 1,300 V, about 80% of the incoming spores were collected and more than 70% of incoming spores formed colonies. These experiments with BG spores have also indicated that there were no signi cant particle losses inside the sampler. The collection ef ciency of biological and nonbiological particles increased to 90-100% when the particles were externally charged and the precipitating voltage was increased to more than § 4,000 V. It has also been shown that the aerosolized BG spores (used as anthrax simulants for bioaerosol sensors) carry a net negative electric charge. Thus the collection ef ciency depends on the polarity of the electric eld applied across the agar plates. These ndings indicate that the collection of airborne microorganisms is possible by electrostatic precipitation without prior electric charging if the microorganisms already carry electric charges. These are usually high immediately after their release into the air.

Physico-chemical characterization of SOA derived from catechol and guaiacol – a model substance for the aromatic fraction of atmospheric HULIS

“…2. The precipitator is based on the concepts of Fierz et al (2007) and Mainelis et al (2002). This ESP has separate charging and deposition zones.…”

Long-Term Sampling of Viable Airborne Viruses

“…Most of the existing bioaerosol samplers utilize one of the following three collection methods: dry filtration, impaction onto a nutrient (e.g., agar), or impingement into a liq-uid. Although some other principles, such as electrostatic precipitation, have been also explored for bacteria (Mainelis et al 1999(Mainelis et al , 2002a(Mainelis et al , 2002b and viruses (Hogan et al 2004), the above three methods are primarily used in the field. Due to a strong desiccation effect and subsequent low microbial recovery, the dry filtration is not generally recommended for a long-term viable bioaerosol monitoring and is primarily used for the total (viable + non-viable) microorganism enumeration (Cox and Wathes 1995).…”

Capture of airborne nanoparticles in swirling flows using non-uniform electrostatic fields for bio-sensor applications

“…Various electrostatic collectors have also been developed to capture bioaerosols from airstreams [1][2][3]. These instruments have an advantage of being operated with a low-pressure drop.…”

“…[1][2][3][4]. Exposure to bioaerosols in indoor and outdoor environments may cause a wide range of health disorders, ranging from mild irritation to a serious disease.…”