Estimation of reduced and increasing health risks by installation of urban wastewater systems

Integrating life cycle assessment with quantitative microbial risk assessment for a holistic evaluation of sewage treatment plant

An integrated approach was employed in the present study to combine life cycle assessment (LCA) with quantitative microbial risk assessment (QMRA) to assess an existing sewage treatment plant (STP) at Roorkee, India. The midpoint LCA modeling revealed that high electricity consumption (≈ 576 kWh.day^-1) contributed to the maximum environmental burdens. The LCA endpoint result of 0.01 disability-adjusted life years per person per year (DALYs pppy) was obtained in terms of the impacts on human health. Further, a QMRA model was developed based on representative sewage pathogens, including E. coli O157:H7, Giardia sp., adenovirus, norovirus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The public health risk associated with intake of pathogen-laden aerosols during treated water reuse in sprinkler irrigation was determined. A cumulative health risk of 0.07 DALYs pppy was obtained, where QMRA risks contributed 86 % of the total health impacts. The annual probability of illness per person was highest for adenovirus and norovirus, followed by SARS-CoV-2, E. coli O157:H7 and Giardia sp. Overall, the study provides a methodological framework for an integrated LCA-QMRA assessment which can be applied across any treatment process to identify the hotspots contributing maximum environmental burdens and microbial health risks. Furthermore, the integrated LCA-QMRA approach could support stakeholders in the water industry to select the most suitable wastewater treatment system and establish regulations regarding the safe reuse of treated water.

The application of life cycle assessment (LCA) to wastewater treatment: A best practice guide and critical review

Life cycle assessment (LCA) has been widely applied in the wastewater industry, but inconsistencies in assumptions and methods have made it difficult for researchers and practitioners to synthesize results from across studies. This paper presents a critical review of published LCAs related to municipal wastewater management with a focus on developing systematic guidance for researchers and practitioners to conduct LCA studies to inform planning, design, and optimization of wastewater management and infrastructure (wastewater treatment plants, WWTPs; collection and reuse systems; related treatment technologies and policies), and to support the development of new technologies to advance treatment objectives and the sustainability of wastewater management. The paper guides the reader step by step through LCA methodology to make informed decisions on i) the definition of the goal and scope, ii) the selection of the functional unit and system boundaries, iii) the selection of variables to include and their sources to obtain inventories, iv) the selection of impact assessment methods, and v) the selection of an effective approach for data interpretation and communication to decision-makers.

Review of Environmental Assessment Case Studies Blending Elements of Risk Assessment and Life Cycle Assessment

Risk assessment (RA) and life cycle assessment (LCA) are two analytical tools used to support decision making in environmental management. This study reviewed 30 environmental assessment case studies that claimed an integration, combination, hybridization, or complementary use of RA and LCA. The focus of the analysis was on how the respective case studies evaluated emissions of chemical pollutants and pathogens. The analysis revealed three clusters of similar case studies. Yet, there seemed to be little consensus as to what should be referred to as RA and LCA, and when to speak of combination, integration, hybridization, or complementary use of RA and LCA. This paper provides clear recommendations toward a more stringent and consistent use of terminology. Blending elements of RA and LCA offers multifaceted opportunities to adapt a given environmental assessment case study to a specific decision making context, but also requires awareness of several implications and potential pitfalls, of which six are discussed in this paper. To facilitate a better understanding and more transparent communication of the nature of a given case study, this paper proposes a "design space" (i.e., identification framework) for environmental assessment case studies blending elements of RA and LCA. Thinking in terms of a common design space, we postulate, can increase clarity and transparency when communicating the design and results of a given assessment together with its potential strengths and weaknesses.

Including pathogen risk in life cycle assessment of wastewater management. 1. Estimating the burden of disease associated with pathogens

The environmental performance of wastewater and sewage sludge management is commonly assessed using life cycle assessment (LCA), whereas pathogen risk is evaluated with quantitative microbial risk assessment (QMRA). This study explored the application of QMRA methodology with intent to include pathogen risk in LCA and facilitate a comparison with other potential impacts on human health considered in LCA. Pathogen risk was estimated for a model wastewater treatment system (WWTS) located in an industrialized country and consisting of primary, secondary, and tertiary wastewater treatment, anaerobic sludge digestion, and land application of sewage sludge. The estimation was based on eight previous QMRA studies as well as parameter values taken from the literature. A total pathogen risk (expressed as burden of disease) on the order of 0.2-9 disability-adjusted life years (DALY) per year of operation was estimated for the model WWTS serving 28,600 persons and for the pathogens and exposure pathways included in this study. The comparison of pathogen risk with other potential impacts on human health considered in LCA is detailed in part 2 of this article series.

Including pathogen risk in life cycle assessment of wastewater management. 2. Quantitative comparison of pathogen risk to other impacts on human health

Resource recovery from sewage sludge has the potential to save natural resources, but the potential risks connected to human exposure to heavy metals, organic micropollutants, and pathogenic microorganisms attract stakeholder concern. The purpose of the presented study was to include pathogen risks to human health in life cycle assessment (LCA) of wastewater and sludge management systems, as this is commonly omitted from LCAs due to methodological limitations. Part 1 of this article series estimated the overall pathogen risk for such a system with agricultural use of the sludge, in a way that enables the results to be integrated in LCA. This article (part 2) presents a full LCA for two model systems (with agricultural utilization or incineration of sludge) to reveal the relative importance of pathogen risk in relation to other potential impacts on human health. The study showed that, for both model systems, pathogen risk can constitute an important part (in this study up to 20%) of the total life cycle impacts on human health (expressed in disability adjusted life years) which include other important impacts such as human toxicity potential, global warming potential, and photochemical oxidant formation potential.

Potential chemical and microbiological risks on human health from urban wastewater reuse in agriculture. Case study of wastewater effluents in Spain

Potential health risks derived from wastewater reuse in agriculture have been evaluated with Risk Assessment modelling techniques, in a case study involving the effluents of two Spanish wastewater treatment plants. One of the plants applies primary and secondary treatment, and the other one applies an additional tertiary treatment. Health risks were assessed on the basis of ingesting contaminated food, due to exposure to: (i) 22 chemical pollutants, namely pharmaceuticals and personal care products (PPCPs), and priority pollutants included in the European Framework Directive, and (ii) microorganisms, namely enterovirus. Chemical Risk Assessment has been carried out following the European Commission's technical guidelines, while risks from exposure to viruses have been evaluated by means of Quantitative Microbial Risk Assessment, assuming a virus to coliform ratio of 1:10(5). The results of the chemical assessment show that there is a margin of safety above 100 for all substances, with the exception of gemfibrozil, for which the mean margin of safety (MOS) is above 100, but the lower bound of MOS with a 95 % confidence interval lies in the 3-4 range. A MOS under 100 was also found for 2,3,7,8-TCDD in one of the effluents. The assessment of risks from viruses shows a very low probability of infection. The overall results show that risks are lower for the plant applying tertiary treatment, especially concerning microbiological parameters.

Hydro-epidemiology: the emergence of a research agenda

There is a growing international awareness of the health risks associated with water, and particularly in developing countries. For example: (i) a child dies in Africa every 30s due to malaria-a disease related to stagnant water, (ii) every year flooding causes many deaths world-wide, with infant mortality due to diarrhea from contaminated flood waters posing the biggest threat, and (iii) poor sanitation and its relation to hepatitis A continues to be a serious problem. A revealing measure of the extent of such global problems is that more than half of the hospital beds in the world today are occupied by people with water-related diseases. Addressing these issues mandates an interdisciplinary approach by the world's scientific and engineering community. In this spirit a workshop was held in Phoenix to provide a forum where epidemiologists, hydraulics researchers and other stakeholders of varied backgrounds (e.g., policy makers, environmental groups etc.) could all participate in a debate on a future agenda for hydro-epidemiology. The principal outcome of the workshop was a significant appreciation of the potential for interdisciplinary research and development in hydro-epidemiology and the major contribution that hydraulics professionals could offer, in partnership with the public health community, in addressing such water related disease control and prevention challenges.