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Application of Advanced Oxidation Processes in Combined Systems for Wastewater Reuse
Published in Maulin P. Shah, Sweta Parimita Bera, Günay Yıldız Töre, Advanced Oxidation Processes for Wastewater Treatment, 2022
Feryal Akbal, Burcu Özkaraova, Ayşe Kuleyin
Most wastewaters from combined systems (e.g., gray water and black water, domestic and industrial wastewater) contain high numbers of various pathogenic microorganisms from toilet and urinal flushing. Past experiences have shown that especially excreta-related infections such as hepatitis, polio, schistosomiasis, cholera and typhoid may occur because of a lack of or improper treatment of wastewater. Thus, any end use with an intended or unintended exposure pathway to an adult (e.g., farmer, worker, consumer, etc.) or child will create risks to human and public health. Thus, as WHO suggests, a risk-based approach may help to determine the best precautions, level of water treatment (secondary/tertiary/advanced, with/without disinfection), and infrastructures (e.g., reservoir, distribution and/or irrigation system) to protect humankind and the environment (soil, ground and surface water). Quantitative microbial risk analysis (QMRA) is the most widely used analysis of health risks from pathogens.
Water quality and standards
Published in Sandy Cairncross, Richard Feachem, Environmental Health Engineering in the Tropics, 2018
Sandy Cairncross, Richard Feachem
In the past, the World Health Organization published guidelines for the quality of drinking water based on the principle that no indicator bacteria should be detectable; for irrigation water on the basis that no excess cases of disease should be detectable; and for bathing water to keep the risk of bathing-related disease to within an acceptable level. In recent years, these guidelines have been revised to harmonise their underlying principles, basing all three on the principles of quantitative microbial risk assessment (QMRA) and management. QMRA seeks to estimate the risk from each level of exposure to a specific pathogen (or toxic chemical) by combining dose-response information for that agent with information on the distribution of exposures (Haas, 1999). The aim is to develop an evidence-based model predicting the risk of disease associated with each level of contamination, to set a maximum tolerable risk, and hence deduce the maximum acceptable level of contamination. In practice, experimental evidence (E) is usually combined with assumptions (A).
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Published in Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse, Routledge Handbook of Water and Health, 2015
Increasingly it has been recognized that there is no direct correlation between numbers of any indicator and enteric pathogens. As a consequence of the possible ambiguity of the term ‘microbial indicator’, Ashbolt et al. (2001) note that the following terms are now recognized: 1. general (process) microbial indicators, 2. fecal indicators and 3. index and model organisms. Meanwhile, recent advances in molecular microbiology have supported the standardization and automation of methods to enumerate genes copies from specific waterborne pathogens (Girones et al., 2010) and tools are emerging that may further elucidate the ecological behavior of enteric organisms beyond the gut environment. Although concerns continue to be expressed about the uncertain relationship between numbers of infectious organisms and concentrations of nucleic acid targets in environmental samples, quantitative real-time polymerase chain reaction (qPCR) is now extensively used to support the burgeoning field of quantitative microbial risk assessment (QMRA). In addition, in the evolving field of quantitative microbial source tracking (QMST) the identification and enumeration of microbial species and groups of specifically human origin (or other specified animal groups) have begun to inform decision-making in the fields of watershed and recreational water management.
Development of a Multiphase Inactivation Model for an Advanced Oxidation Process and Uncertainty Analysis in Quantitative Microbial Risk Assessment
Published in Ozone: Science & Engineering, 2018
Liang Zhou, Shinya Echigo, Tomohiro Nakanishi, Shouhei Yamasaki, Sadahiko Itoh
Since the 1980s, quantitative microbial risk assessment (QMRA) has increasingly been applied for quantifying the microbial safety of drinking water (Haas, Rose and Gerba 1999; Medema et al. 2006). The risk of infection is calculated from the exposure to pathogens (the chance of ingesting one or more pathogens) and the relationship between dose and response (the chance of infection from the number of pathogens ingested). The number of pathogens in drinking water can be calculated from their concentration in the source water and the reduction efficacy by drinking water treatment. Previous studies (Medema et al. 1999; Teunis and Havelaar 1999; Teunis et al. 1997) indicate that one of the largest uncertainties in QMRA comes from estimating the efficacy of drinking water treatment.
Impact of treatment plant management on human health and ecological risks from wastewater irrigation in developing countries – case studies from Cochabamba, Bolivia
Published in International Journal of Environmental Health Research, 2021
Claudia Cossio, Luis Fernando Perez-Mercado, Jenny Norrman, Sahar Dalahmeh, Björn Vinnerås, Alvaro Mercado, Jennifer McConville
The microbial risks for consumers of lettuce irrigated with wastewater from the studied sources were assessed using the quantitative microbial risk assessment (QMRA) approach developed by Haas et al. (2014). QMRA is a probabilistic modelling procedure to estimate the risk to human health for specific scenarios, based the concentration of the significant pathogen(s), the pathway of exposure and the infectivity of the pathogen. All input variables are defined as probability distributions to account for uncertainties in the input data and Monte Carlo simulations used to estimate the probability of adverse health effects.
Pathogen contamination of groundwater systems and health risks
Published in Critical Reviews in Environmental Science and Technology, 2023
Yiran Dong, Zhou Jiang, Yidan Hu, Yongguang Jiang, Lei Tong, Ying Yu, Jianmei Cheng, Yu He, Jianbo Shi, Yanxin Wang
QMRA has been the authorized method for qualitative and quantitative health risk assessments of groundwater pathogens. Initiating from a proposed hypothesis such as whether the groundwater can cause pathogenic infection, QMRA is typically conducted following the steps including hazard identification, exposure assessment, dose-response assessment, and risk characterization (Figure 3). Based on the selected indicator microbes, the exposed population, exposure pathways, and ingestion dose of pathogens were determined to evaluate the probability of infection by the groundwater (Burch et al., 2021).