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

An integrated framework of life-cycle environmental, human health, and economic impact assessment for urban water systems

Water scarcity presents a pressing and lasting challenge to many large cities, necessitating adaptations in urban water systems. Developing reliable water resources is crucial for enhancing water security, yet concerns regarding costs and environmental impacts persist. To address this, we have developed an integrated framework that combines life cycle assessment (LCA), quantitative microbial risk assessment (QMRA), and life cycle costing (LCC) for evaluating the environmental, public health, and economic impacts of water systems. Our approach culminates in a unified monetary representation encapsulating the overall life-cycle costs of the urban water system borne by all stakeholders. City-wide and district-level water systems in Hong Kong were analyzed to demonstrate the benefits of this integrated LCA-QMRA-LCC approach over individual assessments. By quantifying both private and external costs (e.g., environmental and health impacts), we found that the external costs can exceed 50 % of the private costs in both cases, which would potentially influence the decision-making outcomes. Notably, for the district-level study that compared the use of seawater and reclaimed water for toilet flushing, disparities were unveiled between the individual and integrated assessments, underscoring the necessity of a broad LCA-QMRA-LCC framework. This research equips decision-makers with a comprehensive analytical tool, addressing concerns across a broader spectrum of stakeholders and fostering sustainable and cost-effective urban water management.

Quantifying health risks from wastewater reclamation and agricultural reuse using life cycle assessment and quantitative microbial risk assessment

To mitigate the scarcity of freshwater resources, humans have increasingly reused treated wastewater for various purposes, with irrigation accounting for over 70 % of daily water consumption. While wastewater reuse offers a sustainable solution for conserving potable and non-potable water, the reclamation and reuse processes can have environmental and health implications, including greenhouse gas emissions, energy consumption, and pathogen exposure. Life cycle assessment (LCA) has been employed to assess the midpoint and endpoint level impacts, such as human disease burden. Likewise, quantitative microbial risk assessment (QMRA) is a valuable tool for evaluating local risks, such as pathogen exposures during irrigation. Both the LCA (to quantify endpoint indicators of the human burden) and the QMRA tool (to quantify disease burden on human health) use a common metric, disability-adjusted life years (i.e., DALY), which is a measure of overall disease burden that represents the number of years lost due to ill-health, disability, or early death as per person per year (DALYpppy). By combining LCA and QMRA, we can quantitatively measure the health risks associated with wastewater reclamation and reuse. This study aims to estimate the accumulated health burden attributed to the operation of an anoxic/anoxic/oxic/oxic wastewater treatment process and the subsequent reuse of treated wastewater for agricultural irrigation, using the disability-adjusted life years (DALYs). Our findings indicate that the treatment operations contribute a global human health burden of 8.08×10-7 DALYs per person per year (DALYpppy), while pathogen exposures during irrigation with treated wastewater pose a local health impact of 2.40×10-2 DALYpppy, emphasizing the importance of wastewater disinfection for reuse.

A comprehensive review on human enteric viruses in water: Detection methods, occurrence, and microbial risk assessment

Human enteric viruses, such as norovirus, adenovirus, rotavirus, and enterovirus, are crucial targets in controlling biological contamination in water systems worldwide. Due to their small size and low concentrations in water, effective virus concentration and detection methods are essential for ensuring microbial safety. This paper reviews the typical and innovative methods for concentrating and detecting human enteric viruses, highlights viral contamination levels across different water bodies, and discusses the removal efficiencies of virus through various treatment technologies. The application and current gaps of quantitative microbial risk assessment (QMRA) for evaluating the risks of human enteric viruses is also explored. Innovative methods such as digital polymerase chain reaction and isothermal amplification show promise in sensitivity and convenience, however, distinguishing between infectious and non-infectious viruses should be a key focus of future detection techniques. The highest concentrations of human enteric viruses were detected in wastewater, ranging from 103 to 106 copies/L, while drinking water showed significantly lower concentrations, often below 102 copies/L. QMRA studies suggest that exposure to human enteric viruses, whether through contaminated drinking water, occupational contact, or accidental wastewater discharge, could result in a life expectancy of 1.96 × 10-4 to 4.53 × 10-1 days/year.

A unit process log reduction database for water reuse practitioners

Pathogen reduction for the purpose of human health protection is a critical function provided by water reuse systems. Pathogen reduction performance potential is dependent on a wide range of design and operational parameters. Poor understanding of pathogen reduction performance has important consequences-under treatment can jeopardize human health, while over treatment can lead to unnecessary costs and environmental impacts. Documented pathogen reduction potential of the unit processes that make up water reuse treatment trains is based on a highly dispersed and unstructured literature, creating an impediment to practitioners looking to design, model or simply better understand these systems. This review presents a database of compiled log reduction values (LRVs) and log reduction credits (LRCs) for unit processes capable of providing some level of pathogen reduction, with a focus on processes suitable for onsite non-potable water reuse systems. Where reported, we have also compiled all relevant design and operational factors associated with the LRVs and LRCs. Overall, we compiled over 1100 individual LRV data entries for 31 unit processes, and LRCs for 8 unit processes. Results show very inconsistent reporting of influencing parameters, representing a limitation to the use of some of the data. As a standalone resource, the database (included as Supplemental Information) provides water reuse practitioners with easy access to LRV and LRC data. The database is also part of a longer-term effort to optimize the balance between human health protection, potential environmental impacts and cost of water reuse treatment trains.

Assessing sustainability of microalgae-based wastewater treatment: Environmental considerations and impacts on human health

An integrated life cycle assessment (LCA) and quantitative microbial risk assessment (QMRA) were conducted to assess microalgae-mediated wastewater disinfection (M-WWD). M-WWD was achieved by replacing ultraviolet disinfection with a microalgal open raceway pond in an existing sewage treatment plant (STP) in India. Regarding impacts on human health, both M-WWD and STP yielded comparable life cycle impacts, around 0.01 disability-adjusted life years (DALYs) per person per year. However, QMRA impacts for M-WWD (0.053 DALYs per person per year) were slightly lower than that for STP while considering exposure to E. coli O157:H7 and adenovirus. Additionally, a comparative LCA resolved the dilemma about the appropriate utilization of microalgal biomass. Among biodiesel, biocrude, and biogas production, the lowest impacts of 0.015 DALYs per person per year were obtained for biocrude for 1 m3 water treated by M-WWD. Electricity consumption in microalgae cultivation was a major environmental hotspot. Overall, M-WWD, followed by production of microalgal biocrude, emerged as a sustainable alternative from environmental and public health perspectives. These findings set the foundation for pilot-scale M-WWD system development, testing, and economic evaluation. Such comprehensive investigations, encompassing LCA, QMRA, and resource recovery scenarios, offer crucial insights for stakeholders and decision-makers in wastewater treatment and environmental management.

Targeted amplicon sequencing facilitated a novel risk assessment framework for assessing the prevalence of broad spectrum bacterial and coronavirus diseases

How to effectively leverage wastewater data to estimate the risk of various infectious diseases remains a great challenge. To address this issue, we conducted continuous wastewater surveillance in Dalian city during the summer-autumn seasons of 2022, targeting coronavirus and bacterial diseases. The surveillance included daily sampling at a wastewater treatment plant (WWTP) and weekly sampling in three sewersheds. Targeting the bacteria's 16S rRNA gene and the coronavirus's RNA-dependent RNA polymerase (RdRp) gene, we first employed RT-PCR and amplicon sequencing techniques to analyze the presence and phylogenetic relationship of detected coronavirus and bacterial pathogens. Next, qPCR was used to quantify the abundances of detected coronavirus and bacterial species. Based on the daily shedding dynamics of SARS-CoV-2, a novel model was developed to predict daily new cases. Based on the medium shedding density of 12 pathogens, two thresholds of sewage pathogen load (indicating 0.1 % and 1 % infection rates) were proposed. Our PanCoV RT-PCR detected coronavirus on 12th August and from 26th August to 12th September 2022. Targeted amplicon sequencing further identified human coronavirus OC43 (hCoV-OC43) on 12th August and the SARS-CoV-2 Omicron variant since 26th August in samples from WWTPs and sewersheds. Phylogenetic analysis revealed that hCoV-OC43 from this study belonged to genotype K and suggested a close relationship between the amplified coronavirus sequences from wastewater and clinical samples in a local COVID-19 outbreak on 26th August. Amplicon sequencing targeting the bacterial 16S rRNA gene also revealed the presence of several bacterial pathogens. Finally, we assessed the microbial risk of specific pathogens in sewersheds and identified a number of pathogens that reached high (>1 % prevalence) and medium risk levels (>0.1 % prevalence) at sewershed B. Our findings underline wastewater surveillance as a valuable early warning system for coronavirus and other waterborne bacterial diseases, complementing public health response measures.

Quantitative Risk Assessment of Five Foodborne Viruses in Shellfish Based on Multiplex qPCR

Foodborne diseases are currently the most critical food safety issue in the world. There are not many hazard identification and exposure assessments for foodborne viruses (Norovirus GI, GII, Hepatitis A Virus, Rotavirus, Adenovirus) in shellfish. Multiplex qPCR for the simultaneous detection of five foodborne viruses was established and used to assess infection risk based on a 1-year pathogenesis study. The sensitivity, specificity and reproducibility of the multiplex qPCR method are consistent with that of conventional qPCR, which saves more time and effort. Overall, 37.86% of shellfish samples had one or more foodborne viruses. Risk assessment formulae and matrices were used to develop risk assessments for different age groups, different seasons and different shellfish. The annual probability of contracting a foodborne virus infection from shellfish is greater than 1.6 × 10-1 for all populations, and even for infants aged 0-4 years, it is greater than 1.5 × 10-2, which is much higher than the risk thresholds recommended by WHO (10-6) and the US EPA (10-4). High risk (level IV) is associated with springtime, and medium risk (level III) is associated with Mussel consumption. This study provides a basis for the risk of foodborne viral infections in people of different ages, in different seasons, and by consuming different shellfish.