scholarly journals Bioaerosol in a typical municipal wastewater treatment plant: concentration, size distribution, and health risk assessment

2020 ◽  
Vol 82 (8) ◽  
pp. 1547-1559
Author(s):  
Pengcheng Xu ◽  
Chongmiao Zhang ◽  
Xiao Mou ◽  
Xiaochang C. Wang

Abstract An investigation on bioaerosol in a wastewater treatment plant (WWTP) located in Xi'an, China, was conducted to understand the characteristics of bioaerosol released from wastewater and sludge treatment facilities because the bioaerosols may pose a threat to human health. Using the Andersen impactor sampler collection and colony-counting method, bioaerosol concentrations and size distributions were detected. The risk quotient method was used to evaluate the health risks associated with inhalation of bioaerosol for WWTP staff, based on the average daily dose rates of exposure. The health risk in relation to Legionella pneumophila was quantitatively calculated using quantitative microbial risk assessment (QMRA), based on the assumption of the percentage. The maximum concentration of airborne bacteria (3,767 ± 280 colony forming units (CFU)/m3) and fungi (8,775 ± 406 CFU/m3) occurred from the aerated grit chamber and sludge thickening house, respectively, which all exceeded 500 CFU/m3 as the acceptable guideline proposed by the American Conference of Governmental Industrial Hygienists. The particle size of airborne bacteria was mainly distributed in the first three stages (>3.3 µm), while that of airborne fungi was from the second to the fourth stage (2.1–7.0 µm). The hazard index exposure to bioaerosol for adult males and females by inhalation were higher than 1. The proportion of L. pneumophila should be strictly controlled below 10−8, based on the QMRA approach.

2021 ◽  
Author(s):  
Jia-xin Ma ◽  
Bei-bei Cui ◽  
Man-li Liu ◽  
Jie Yuan ◽  
Cheng Yan

Abstract Biological treatment in wastewater treatment plants (WWTPs) releases high amounts of bioaerosols carrying a variety of pathogens. Quantitative microbial risk assessment (QMRA) is a framework prevalently intended for the quantitative estimation of health risks for occupational exposure scenarios (e.g. in WWTPs). However, the quantitative contributions of health-risk-estimate inputted variable parameters remain ambiguous. Therefore, this research aimed to study the disease burden of workers exposed to Staphylococcus aureus bioaerosol during warm and cold periods and to strictly quantify the contributions of the inputted parameters of disease burden by sensitivity analysis based on Monte Carlo simulation. The results showed that the disease health risk burden in the warm period was higher than in the cold period, disease health risk burden in the rotating-disc aeration mode was regularly higher than in the microporous aeration mode. The disease health risk burden of the workers with personal protective equipment (PPE) almost all satisfied the WHO benchmark (≤10E-6 DALYs pppy), and was consistently lower by one or two orders of magnitude than the workers without PPE in both warm and cold periods. Referring to the sensitivity analysis, exposure concentration and aerosol ingestion rate were the most and second predominant factor for the estimated risk in all exposure scenarios, respectively. The sensitivity of the removal fraction by employing PPE ranked third in the contribution to disease health risk burden. In addition, no remarkable differences were revealed in the sensitivity percentage ratio between warm and cold periods. This research can deepen the understanding of the QMRA framework and promote the development of sensitivity analysis, especially under various meteorological conditions (warm and cold periods).


Water ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 23 ◽  
Author(s):  
Magdalena Łój-Pilch ◽  
Anita Zakrzewska

Nowadays, risk management applies to every technical facility, branch of the economy, and industry. Due to the characteristics of the analyzed wastewater treatment plant and the specificity of the used processes, one must approach different areas individually. Municipal sewage treatment plants are technical facilities; they function as enterprises and are elements of larger systems—water distribution and sewage disposal. Due to their strategic importance for the environment and human beings, it is essential that they are covered by risk management systems. The basic stage of risk management is its assessment. On its basis, strategic decisions are made and new solutions are introduced. Constant monitoring of the operation of a treatment plant allows for assessment of whether actions taken are correct and whether they cause deterioration of the quality of sewage. In our work, we present a method of risk assessment based on historical data for an existing facility and obtained results.


Author(s):  
Hubert Byliński ◽  
Jacek Gębicki ◽  
Jacek Namieśnik

The paper describes an attempt at health risk assessment and odour concentration determination in the most important units of a wastewater treatment plant. The cancer risk (CR) and hazard index (HI) parameters in selected measurement locations were calculated based on the results of chromatographic analyses (GCxGC-TOF-MS) and the United States Environmental Protection Agency (US EPA) guidelines. No exceedance of the CR and HI acceptable levels was observed for identified and quantitatively determined compounds from the VOCs group. The acceptable level was exceeded for the summary HI parameter. Following a classification of the International Agency for Research on Cancer (IARC), it was noticed that the highest hazard was connected to the presence of formaldehyde belonging to group 1—the compounds regarded as carcinogenic. Based on the olfactometric analyses, it was estimated that the highest odour concentration, 37.2 ou/m3, occurred at the solid waste composting piles. It was also revealed that an increase in odour concentration corresponded to a higher health risk for employees of the wastewater treatment plant, due to exposure to volatile odorous compounds. Accordingly, this method of odour measurement can be a fast indicator describing health risk level.


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