Bacterial-aerosol emission from wastewater treatment plant

Abstract

A B S T R A C TBioaerosols' emission from an activated sludge wastewater treatment plant with surface aerators was surveyed from November 2009 to July 2010. Health effects among plant workers were assessed by checklist and through interviews by an internist. Samples were collected by the Anderson sampler in eight days of the year and analyzed for Standard Plate Count, Total Coliforms, Fecal Coliforms, and Fecal Streptococci. It was found that most sewage treatment plant's staffs were adversely affected as a result of bioaerosols' inhalation. Major observed health effects were fatigue, dizziness, eye irritation, and abdominal pain. The most common size of bacterial-aerosols was higher than 8.2 lm. Maximum and minimum concentrations of bacterial-aerosols were found in the sludge aerobic digester unit (1537 CFU/m 3 ) and the secondary settlers (4 CFU/m 3 ), respectively. Average concentrations of bacterial-aerosols were much lower in summer (742 CFU/m 3 ) as compared to winter (3780 CFU/m 3 ). Given the observed adverse health effects of bioaerosols on employees and their presence in collected air samples, measures to prevent and reduce the spread of bacterial-aerosols in the environment were necessary and the use of personal protection equipments was deemed to be imperative.

Site-related and seasonal variation of bioaerosol emission in an indoor wastewater treatment station: level, characteristics of particle size, and microbial structure

“…Bioaerosols emitted from different stages in an activated sludge wastewater treatment plant have been collected by an Anderson sampler (Malakootian et al 2013). The maximum concentrations of bacterial aerosols have been found in the sludge aerobic digester unit (1537 CFU/m 3 ).…”

Investigation of type and density of bio-aerosols in air samples from educational hospital wards of Kerman city, 2014

“…Around 10% of hospital infections in hospitalized patients without any underlying disease were caused by organisms transmitted through air (15). Moreover, the degree of emission of bioaerosols in the air surrounding Kerman city wastewater treatment plant was examined by Malakootian et al (16). As hospital infection caused problems such as prolongation of hospitalization time, development of disease, decreased productivity in a working environment as well as staff absence; such problems placed a heavy cost burden to health systems in developing countries (17).…”

Activated Sludge

“…Bioaerosol concentrations are usually higher during night than day time with a lack of solar radiation and lower temperatures to reduce bioaerosols (Karra and Katsivela, 2007). Furthermore, bioaerosols may have higher concentrations in colder (winter and fall) months than warmer (spring and summer) months because of temperature differences (Malakootian et al, 2013). However, Fracchia et al 2006 found no seasonal trends in bioaerosol concentrations in their study in Italy.…”

“…Bioaerosol concentrations from activated sludge systems are dependent on a number of operational and environmental parameters. When inhaled from the air or ingested after touching a surface contaminated with pathogenic bioaerosols, they can cause negative health consequences to sewage treatment workers such as stomach pain, fatigue, dizziness, eye irritation and headaches (Oppliger et al, 2005;Malakootian et al, 2013). Neighboring communities could also be at risk if concentrations are high enough and they are in close proximity to activated sludge treatment plants.…”

“…a Bauer et al, 2002;b Guo et al, 2014;c Brandi et al, 2000;d Fracchia et al, 2006;e Sánchez-Monedero et al, 2008;f Fernando and Fedorak, 2005; g Pascual et al 2003;h Malakootian et al, 2013; i Karra and Katsivela, 2007;j Li et al, 2016; k Carducci et al, 2000 Activated sludge systems include more than the activated sludge tank but also the secondary settling tank, waste activated and return activated sludge, and may include sampling sinks for the Mixed Liquor Suspended Solids (MLSS) for the activated sludge to ensure it is operating properly. Table 4 displays the range of bacteria in bioaerosols in the different components of the activated sludge system from various studies.…”