| 1. |
- Bergion, Viktor, 1986, et al.
(författare)
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Accounting for Unexpected Risk Events in Drinking Water Systems
- 2021
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Ingår i: Exposure and Health. - : Springer Science and Business Media LLC. - 2451-9685 .- 2451-9766. ; 13:1, s. 15-31
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Tidskriftsartikel (refereegranskat)abstract
- Unexpected risk events in drinking water systems, such as heavy rain or manure spill accidents, can cause waterborne outbreaks of gastrointestinal disease. Using a scenario-based approach, these unexpected risk events were included in a risk-based decision model aimed at evaluating risk reduction alternatives. The decision model combined quantitative microbial risk assessment and cost–benefit analysis and investigated four risk reduction alternatives. Two drinking water systems were compared using the same set of risk reduction alternatives to illustrate the effect of unexpected risk events. The first drinking water system had a high pathogen base load and a high pathogen log10 reduction in the treatment plant, whereas the second drinking water system had a low pathogen base load and a low pathogen Log10 reduction in the treatment plant. Four risk reduction alternatives were evaluated on their social profitability: (A1) installation of pumps and back-up power supply, to remove combined sewer overflows; (A2) installation of UV treatment in the drinking water treatment plant; (A3) connection of 25% of the OWTSs in the catchment area to the WWTP; and (A4) a combination of A1–A3. Including the unexpected risk events changed the probability of a positive net present value for the analysed alternatives in the decision model and the alternative that is likely to have the highest net present value. The magnitude of the effect of unexpected risk events is dependent on the local preconditions in the drinking water system. For the first drinking water system, the unexpected risk events increase risk to a lesser extent compared to the second drinking water system. The main conclusion was that it is important to include unexpected risk events in decision models for evaluating microbial risk reduction, especially in a drinking water system with a low base load and a low pathogen log10 reduction in the drinking water treatment plant.
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| 2. |
- Bergion, Viktor, 1986
(författare)
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Development of a Risk-Based Decision Model for Prioritizing Microbial Risk Mitigation Measures in Drinking Water Systems
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Risk management of drinking water systems is crucial since our society relies on these systems to be robust and sustainable to supply safe drinking water now and to future generations. Pathogens may spread in drinking water systems and cause waterborne outbreaks resulting in human suffering and large costs to the society. Thus, mitigating microbial risks is of great importance for provision of safe drinking water in a changing world. Since risk mitigation measures can be costly, there is a need for a transparent and holistic decision support to enable a sound and efficient use of available resources. In this thesis, a risk-based decision model that facilitates evaluation and comparison of microbial risk mitigation measures is presented. The model was developed by combining source characterisation, water quality modelling, quantitative microbial risk assessment and cost-benefit analysis. Uncertainties associated with input variables and output results were analysed by means of Monte Carlo simulations. The decision model puts emphasis on health benefits obtained from reduced microbial risks in drinking water systems and the monetisation of these effects. In addition, the approach also accounts for non-health benefits that occur because of implemented mitigation measures. Such benefits, also if they cannot be monetised, are important to include and carefully consider in the cost-benefit analysis. The probabilistic approach provides an analysis of uncertainties that need to be considered by decision makers. To conclude, this thesis underlines and illustrates the strength of combining methods from several disciplines to create a robust decision support in order to optimise societal benefits.
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| 3. |
- Bergion, Viktor, 1986, et al.
(författare)
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Economic Valuation for Cost–Benefit Analysis of Health Risk Reduction in Drinking Water Systems
- 2020
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Ingår i: Exposure and Health. - : Springer Science and Business Media LLC. - 2451-9685 .- 2451-9766. ; 12:1, s. 99-110
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Tidskriftsartikel (refereegranskat)abstract
- Microbial risk mitigation measures in drinking water systems aiming at preventing gastrointestinal disease can provide substantial societal health benefits if implemented properly. However, the procedure of including and monetising the health benefits in cost–benefit analysis (CBA) has been somewhat scattered and inconsistent in the literature, and there is a need for a comparison of available methods. First, through a literature review, we identified the methods to include health benefits in decision support and to monetise these benefits in CBA. Second, we applied the identified health valuation methods in a case study. In the case study, we investigated if changing the health valuation method could change the rank order of the decision alternatives’ net present values. In the case study a risk-based decision model that combined quantitative microbial risk assessment and CBA was used. Seven health valuation methods were identified, each of them including different aspects of health benefits. The results of the case study showed that the choice of the health valuation method can change the rank order of decision alternatives with respect to their net present values. These results highlight the importance of choosing an appropriate health valuation method for the specific application. Although this study focused on the drinking water context, the identified health valuation methods can be applied in any decision support context, provided that input in terms of the health risk reduction is available.
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| 4. |
- Bergion, Viktor, 1986, et al.
(författare)
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Hydrological modelling in a drinking water catchment area as a means of evaluating pathogen risk reduction
- 2017
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Ingår i: Journal of Hydrology. - : Elsevier BV. - 0022-1694. ; 544, s. 74-85
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Tidskriftsartikel (refereegranskat)abstract
- Waterborne outbreaks of gastrointestinal diseases are of great concern to drinking water producers and can give rise to substantial costs to the society. The World Health Organisation promotes an approach where the emphasis is on mitigating risks close to the contamination source. In order to handle microbial risks efficiently, there is a need for systematic risk management. In this paper we present a framework for microbial risk management of drinking water systems. The framework incorporates cost-benefit analysis as a decision support method. The hydrological Soil and Water Assessment Tool (SWAT) model, which was set up for the Stäket catchment area in Sweden, was used to simulate the effects of four different mitigation measures on microbial concentrations. The modelling results showed that the two mitigation measures that resulted in a significant (p
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| 5. |
- Bergion, Viktor, 1986, et al.
(författare)
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Risk-based cost-benefit analysis for evaluating microbial risk mitigation in a drinking water system
- 2018
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 132, s. 111-123
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Tidskriftsartikel (refereegranskat)abstract
- Waterborne outbreaks of gastrointestinal diseases can cause large costs to society. Risk management needs to be holistic and transparent in order to reduce these risks in an effective manner. Microbial risk mitigation measures in a drinking water system were investigated using a novel approach combining probabilistic risk assessment and cost-benefit analysis. Lake Vomb in Sweden was used to exemplify and illustrate the risk-based decision model. Four mitigation alternatives were compared, where the first three alternatives, A1-A3, represented connecting 25, 50 and 75%, respectively, of on-site wastewater treatment systems in the catchment to the municipal wastewater treatment plant. The fourth alternative, A4, represented installing a UV-disinfection unit in the drinking water treatment plant. Quantitative microbial risk assessment was used to estimate the positive health effects in terms of quality adjusted life years (QALYs), resulting from the four mitigation alternatives. The health benefits were monetised using a unit cost per QALY. For each mitigation alternative, the net present value of health and environmental benefits and investment, maintenance and running costs was calculated. The results showed that only A4 can reduce the risk (probability of infection) below the World Health Organization guidelines of 10−4 infections per person per year (looking at the 95th percentile). Furthermore, all alternatives resulted in a negative net present value. However, the net present value would be positive (looking at the 50th percentile using a 1% discount rate) if non-monetised benefits (e.g. increased property value divided evenly over the studied time horizon and reduced microbial risks posed to animals), estimated at 800–1200 SEK (€100–150) per connected on-site wastewater treatment system per year, were included. This risk-based decision model creates a robust and transparent decision support tool. It is flexible enough to be tailored and applied to local settings of drinking water systems. The model provides a clear and holistic structure for decisions related to microbial risk mitigation. To improve the decision model, we suggest to further develop the valuation and monetisation of health effects and to refine the propagation of uncertainties and variabilities between the included methods.
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| 6. |
- Bergion, Viktor, 1986
(författare)
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Risk-Based Decision Model for Microbial Risk Mitigation in Drinking Water Systems
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Microbial risks in drinking water systems can cause sporadic pathogenic infections and waterborne outbreaks resulting in large costs for society. In 2010 for example, around 27,000 persons were infected with Cryptosporidium in Östersund, Sweden. It is so far the largest waterborne outbreak in Europe, and societal costs were estimated at SEK 220 million (approx. 20 million €). To achieve a safe drinking water supply, assessment of microbial risks and, when needed, implementation of risk mitigation measures is necessary. However, drinking water systems are complex, and risk mitigation measures are expensive. A thorough evaluation of possible mitigation measures is thus essential for identification of the most suitable alternative and efficient use of societal resources. In this thesis, a risk-based decision model for evaluating and comparing microbial risk mitigation measures in drinking water systems is presented and illustrated using two Swedish case studies. The decision model combines quantitative microbial risk assessment and cost-benefit analysis in order to evaluate decision alternatives from the perspective of social profitability. The quantitative microbial risk assessment is complemented with water quality modelling and consideration of unexpected risk events, such as extreme weather events and combined sewer overflows, in order to reflex the complexity of drinking water systems. To facilitate transparent cost-benefit analyses, the effect of different health valuation methods on the output from the decision model is presented. In the decision model, health benefits and other benefits are monetised for each mitigation measure and compared to the costs for implementing the measure. It is possible to combine decision criteria such as tolerable risk levels and maximising the net present value when applying the decision model. The decision model integrates several scientific disciplines, thus constituting a novel approach to evaluate microbial risk mitigation measures in drinking water systems and provides a structured analysis that includes often neglected aspects. The model provides transparent and holistic decision support and facilitates well-founded decisions balancing risks, costs and societal benefits.
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| 7. |
- Chuquimia, Olga D., et al.
(författare)
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Molecular analyses of fecal bacteria and hydrodynamic modeling for microbial risk assessment of a drinking water source
- 2020
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Ingår i: Water (Switzerland). - : MDPI AG. - 2073-4441 .- 2073-4441. ; 12:1
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Tidskriftsartikel (refereegranskat)abstract
- Safe water is a global concern, and methods to accurately monitor quality of water are vital. To assess the risks related to bacterial pathogen load in Lake Vomb that provides drinking water to the southern part of Sweden, this study combined molecular analyses of enterobacteria and bacterial pathogens in water using quantitiative real-time PCR with hydrodynamic modeling and quantitative microbial risk assessment (QMRA). A real-time PCR assay to detect enterobacteria was set up by primers targeting ssrA. Between February 2015 and May 2016, presence of ssrA gene copies as well as Campylobacter spp., Salmonella spp., and EHEC O157 DNA was analyzed by real-time PCR at several locations in the catchment of Lake Vomb and its tributaries Bjorkaan, Borstbacken, and Torpsbacken. Bjorkaan had the highest detected concentrations of the ssrA gene and, according to the results of hydrodynamic modeling, contributed most to the contamination of the water intake in the lake. None of the water samples were positive for genes encoding EHEC O157 and Campylobacter spp., while invA (Salmonella spp.) was present in 11 samples. The QMRA showed that the suggested acceptable risk level (daily probability of infection <2.7 x 10-7) is achieved with a 95% probability, if the Salmonella concentrations in the water intake are below 101 bacteria/100 mL. If a UV-disinfection step is installed, the Salmonella concentration at the water intake should not exceed 106 bacteria/100 mL.
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| 8. |
- Lindhe, Andreas, 1981, et al.
(författare)
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Utvärdering av statsstödet för bättre vattenhushållning: Enkätstudie av genomförda projekt 2019 och 2020
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Sedan 2019 har det varit möjligt att söka statligt bidrag för åtgärder med syfte att förbättra vattenhushållningen och trygga tillgången på dricksvatten. Bidraget benämns här dricksvattenstödet. I denna rapport presenteras resultaten från en enkätstudie vars syfte varit att utvärdera om dricksvattenstödet bidragit till att trygga tillgången till dricksvatten i Sverige. Enkäten skickades till de som genomfört projekt med finansiering från dricksvattenstödet under åren 2019 och 2020. Totalt besvarades enkäten för 151 projekt, vilket motsvarar 51 % av samtliga projekt som genomfördes under de aktuella åren. Samtliga län som erhållit bidrag från dricksvattenstödet finns också representerade i enkätsvaren. Olika utmaningar ligger bakom de projekt som genomförts, men behov av underlag för strategiska beslut är det vanligaste motivet, följt av bristfällig vattentillgång. För knappt hälften av projekten angavs att de bakomliggande utmaningarna delvis är kopplade till förväntade effekter av klimatförändringar och 13 % svarar ja på frågan. Projektens avsedda effekter är framför allt kopplade till sammanställning eller uppbyggnad av information inom olika områden. Effekter på råvattenförsörjning och kommunala planer är vanligast men andra områden nämns också i många projekt. Av projekten bedöms 88 % helt eller delvis ha uppnått önskad effekt (65 resp. 23 %). Endast 3 % angav att önskad effekt inte uppnåtts (övriga kunde ej bedöma). Vanliga anledningar som anges till varför önskad effekt inte uppnåtts är att projektet är ett steg i arbetet och ytterligare utredning, beslut m.m. krävs. Nästan 40 % av projekten innefattade investering i ny teknik och för dessa projekt bedöms i majoriteten av fallen (87 %) den nya tekniken fungera bra eller mycket bra. En klar majoritet (97 %) av de som besvarade enkäten anser att dricksvattenstödet är viktigt eller mycket viktigt för att trygga dricksvattentillgången. dricksvattenstödets utformning ansågs också vara bra. Det många påpekade som problematiskt var den relativt korta projekttiden. Om denna förlängs skulle det enligt enkätsvaren vara lättare att genomföra det som är planerat i projekten och även utöka projekten, vilket skulle kunna bidra till ytterligare effekter som tryggar tillgången på dricksvatten. Under 2019 och 2020 kunde ettåriga projekt sökas, vilket avspeglar sig i kommentarerna om projektlängden. Numera går det att söka tvååriga projekt. Enkätresultaten visar att om projekten inte erhållit bidrag hade 15 % av dem inte genomförts, men 85 % av projekten hade genomförts på samma sätt som de nu gjorts alternativt med ändringar i tidplan eller omfattning. Stödets utformning gör troligen att dricksvattenstödet framför allt används för att stötta projekt som hade genomförts även utan dricksvattenstödet. Stödet gör det dock möjligt att tidigarelägga vissa åtgärder eller göra mer än vad som annars varit möjligt. Det går inte att ange hur mycket säkrare den svenska dricksvattenförsörjningen blivit till följd av de åtgärder som genomförts med finansiering från dricksvattenstödet. Resultaten från enkätundersökningen visar däremot att dricksvattenstödet har bidragit till projekt som gett en lång rad olika effekter på dricksvattenförsörjningen, vilka också kan kopplas till de utmaningar man ser i branschen. Effekterna som uppnåtts får därför anses ha en positiv effekt på den svenska dricksvattenförsörjningen.
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| 9. |
- Ngubane, Zesizwe, et al.
(författare)
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Multi-criteria decision analysis framework for engaging stakeholders in river pollution risk management
- 2024
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Water pollution presents a substantial environmental challenge with extensive implications for water resources, ecosystem sustainability, and human health. Using a South African catchment, this study aimed to provide watershed managers with a framework for selecting best management practices (BMPs) to reduce pollution and the related risk to river users, while also including the perspectives of key catchment stakeholders. The framework encompassed the identification of and consultation with key stakeholders within the catchment. A Multi-Criteria Decision Analysis (MCDA) methodology using the Simple Multi-Attribute Rating Technique for Enhanced Stakeholder Take-up (SMARTEST) was used to identify and prioritise suitable BMPs in a case study. Decision alternatives and assessment criteria as well as their weights were derived based on stakeholder responses to a two-stage survey. Stakeholders included those utilising the river for domestic and recreational purposes, municipal representatives, scientists, NGOs, and engineers. The assessment of decision alternatives considered environmental, economic, and social criteria. The aggregated scores for decision alternatives highlighted the significance of involving stakeholders throughout the decision process. This study recommends the pairing of structural and non-structural BMPs. The findings provide valuable insights for catchment managers, policymakers, and environmental stakeholders seeking inclusive and effective pollution mitigation strategies in a catchment.
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| 10. |
- Ngubane, Zesizwe, et al.
(författare)
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Water quality modelling and quantitative microbial risk assessment for uMsunduzi River in South Africa
- 2022
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Ingår i: Journal of Water and Health. - : IWA Publishing. - 1996-7829 .- 1477-8920. ; 20:4, s. 641-656
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Tidskriftsartikel (refereegranskat)abstract
- South African rivers generally receive waste from inadequate wastewater infrastructure, mines, and farming activities, among others. The uMsunduzi River in KwaZulu-Natal, South Africa, is among these recipients with recorded poor to very poor water quality. To identify parts of the uMsunduzi River that are polluted by Cryptosporidium and Escherichia coli (E. coli), this study mapped out pollutants emanating from point and non-point sources using the Soil and Water Assessment Tool (SWAT). Streamflow calibration in the upper and lower reaches of the catchment showed good performance with R-2 of 0.64 and 0.58, respectively. SWAT water quality output data were combined with a Quantitative Microbial Risk Assessment (QMRA) to understand the microbial health implications for people using river water for drinking, recreational swimming, and non-competitive canoeing. QMRA results for Cryptosporidium and pathogenic E. coli showed that the probability of infection for most users exceeds the acceptable level for drinking and recreation as outlined in the South African water quality guidelines, and by the World Health Organisation (WHO). The results of this study can be used as a baseline to assess the economic and health implications of different management plans, resulting in better-informed, cost-effective, and impactful decision-making.
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