| 1. |
- Berglund, Björn, et al.
(författare)
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Occurrence and removal efficiency of parasitic protozoa in Swedish wastewater treatment plants
- 2017
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 598, s. 821-827
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Tidskriftsartikel (refereegranskat)abstract
- Giardia intestinalis, Cryptosporidium spp., Entamoeba histolytica and Dientamoeba fragilis are parasitic protozoa and causative agents of gastroenteritis in humans. G. intestinalis and Cryptosporidium spp. in particular are the most common protozoa associated with waterborne outbreaks in high-income countries. Surveillance of protozoan prevalence in wastewater and evaluation of wastewater treatment removal efficiencies of protozoan pathogens is therefore imperative for assessment of human health risk. In this study, influent and effluent wastewater samples from three wastewater treatment plants in Sweden were collected over nearly one year and assessed for prevalence of parasitic protozoa. Quantitative real-time PCR using primers specific for the selected protozoa Cryptosporidium spp., G. intestinalis, E. histolytica, Entamoeba dispar and D. fragilis was used for protozoan DNA detection and assessment of wastewater treatment removal efficiencies. Occurrence of G. intestinalis, E. dispar and D. fragilis DNA was assessed in both influent (44, 30 and 39 out of 51 samples respectively) and effluent wastewater (14, 9 and 33 out of 51 samples respectively) in all three wastewater treatment plants. Mean removal efficiencies of G. intestinalis, E. dispar and D. fragilis DNA quantities, based on all three wastewater treatment plants studied varied between 67 and 87%, 37–75% and 20–34% respectively. Neither E. histolytica nor Cryptosporidium spp. were detected in any samples. Overall, higher quantities of protozoan DNA were observed from February to June 2012. The high prevalence of protozoa in influent wastewater indicates the need for continued monitoring of these pathogens in wastewater-associated aquatic environments to minimise the potential risk for human infection.
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| 2. |
- Dienus, Olaf, et al.
(författare)
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Norovirus Dynamics in Wastewater Discharges and in the Recipient Drinking Water Source: Long-Term Monitoring and Hydrodynamic Modeling
- 2016
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 50:20, s. 10851-10858
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Tidskriftsartikel (refereegranskat)abstract
- Norovirus (NoV) that enters drinking water sources with wastewater discharges is a common cause of waterborne outbreaks. The impact of wastewater treatment plants (WWTPs) on the river Gota alv (Sweden) was studied using monitoring and hydrodynamic modeling. The concentrations of NoV genogroups (GG) I and II in samples collected at WWTPs and drinking water intakes (source water) during one year were quantified using duplex real-time reverse-transcription polymerase chain reaction. The mean (standard deviation) NoV GGI and GGII genome concentrations were 6.2 (1.4) and 6.8 (1.8) in incoming wastewater and 5.3 (1.4) and 5.9 (1.4) log(10) genome equivalents (g.e.) L-1 in treated wastewater, respectively. The reduction at the WWTPs varied between 0.4 and 1.1 log(10) units. In source water, the concentration ranged from below the detection limit to 3.8 log(10) g.e. L-1. NoV GGII was detected in both wastewater and source water more frequently during the cold than the warm period of the year. The spread of NoV in the river was simulated using a three-dimensional hydrodynamic model. The modeling results indicated that the NoV GGI and GGII genome concentrations in source water may occasionally be up to 2.8 and 1.9 log(10) units higher, respectively, than the concentrations measured during the monitoring project.
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| 3. |
- Malm, Annika, 1970, et al.
(författare)
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The association of drinking water treatment and distribution network disturbances with Health Call Centre contacts for gastrointestinal illness symptoms
- 2013
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 47:13, s. 4474-4484
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Tidskriftsartikel (refereegranskat)abstract
- There are relatively few studies on the association between disturbances in drinking waterservices and symptoms of gastrointestinal (GI) illness. Health Call Centres data concerningGI illness may be a useful source of information. This study investigates if there is anincreased frequency of contacts with the Health Call Centre (HCC) concerning gastrointestinal symptoms at times when there is a risk of impaired water quality due to disturbances at water works or the distribution network. The study was conducted inGothenburg, a Swedish city with 0.5 million inhabitants with a surface water source ofdrinking water and two water works. All HCC contacts due to GI symptoms (diarrhoea,vomiting or abdominal pain) were recorded for a three-year period, including also sex, age,and geocoded location of residence. The number of contacts with the HCC in the affectedgeographical areas were recorded during eight periods of disturbances in the water works(e.g. short stops of chlorine dosing), six periods of large disturbances in the distributionnetwork (e.g. pumping station failure or pipe breaks with major consequences), and 818pipe break and leak repairs over a three-year period. For each period of disturbance theobserved number of calls was compared with the number of calls during a control periodwithout disturbances in the same geographical area. In total about 55, 000 calls to the HCCdue to GI symptoms were recorded over the three-year period, 35 per 1000 inhabitants andyear, but much higher (>200) for children
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| 4. |
- Moona, Nashita, 1985, et al.
(författare)
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Full-Scale Manipulation of the Empty Bed Contact Time to Optimize Dissolved Organic Matter Removal by Drinking Water Biofilters
- 2021
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Ingår i: ACS ES and T Water. - : American Chemical Society (ACS). - 2690-0637. ; 1:5, s. 1117-1126
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Tidskriftsartikel (refereegranskat)abstract
- A study was conducted at a water treatment plant to optimize parallel rapid gravity biofilters for dissolved organic matter (DOM) removal. The biofilters treat urban and agriculturally impacted river water using a commercial non-adsorptive, expanded-clay filter medium. The study aimed to locate the optimal operating conditions via experimental manipulation of the biofilter empty bed contact time (EBCT) during full-scale operation at the plant. During a two-month experiment, contact times in four parallel biofilters were switched to and maintained at 15, 30, 50, and 80 min by manipulating the hydraulic loading on each filter. The removal efficiency of organic matter fractions increased with EBCT for dissolved organic carbon (DOC) and microbial humic-like (F290/420) and protein-like (F280/340) fluorescent organic matter. Other DOM fractions were largely unaffected by biofiltration, or at slightly higher concentrations in the effluent. Protein-like fluorescence is associated with labile organic matter fractions, which are known to be removed poorly by drinking water treatment barriers apart from biological filters. The results suggest that long contact times (>30 min) have advantages for the operation of some biological filters, especially if placed ahead of barriers that are sensitive to biofouling, e.g., membranes.
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| 5. |
- Moona, Nashita, 1985, et al.
(författare)
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Partial renewal of granular activated carbon filters for improved drinking water treatment
- 2018
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Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 4:4, s. 529-538
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Tidskriftsartikel (refereegranskat)abstract
- There is a trend of increasing natural organic matter (NOM) in raw drinking waters of Nordic countries due to climate change. Seasonal deterioration in NOM quality imparts challenges for delivering a consistently high drinking water quality. In this study, a simple and cost-effective operational strategy was investigated that improved short-term NOM removal in a full-scale treatment plant. Three granular activated carbon (GAC) media biofilters were modified by replacing a small fraction of saturated filter media with new media. Relative to replacing the entire biofilter media, this approach required lower capital cost and shorter downtime and maintained conditions for biological filter functioning. NOM removal efficiencies were compared in modified versus unmodified (reference) filters using online UV absorbance, and offline fluorescence and dissolved organic carbon measurements. The modified biofilters showed improved organic matter removal lasting for at least four weeks. Partial replenishment of GAC in full-scale biofilters may be a useful and sustainable operational strategy for coping with temporarily high NOM loads in raw waters that might otherwise cause water quality problems.
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| 6. |
- Moona, Nashita, 1985, et al.
(författare)
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Partial replenishment of biological activated carbon filters to improve natural organic matter removal
- 2018
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Ingår i: Proceedings of IWA World Water Congress & Exhibition 2018.
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Konferensbidrag (refereegranskat)abstract
- Natural organic matter (NOM) in surface waters negatively impacts drinking water treatment and is a precursor of harmful disinfection by-products (DBPs). Granular activate carbon (GAC) filters are integral components of many drinking water treatment plants (WTPs) due to the ability to remove NOM and organic micro pollutants from raw waters. However, GAC filters lose adsorption capacity and convert to biologically activated carbon (BAC) filter relatively quickly. This paper reports on a full-scale BAC filter modification strategy to enhance short-term NOM removal. This is achieved by adding a small amount of fresh GAC to BAC filters which increases adsorption while maintaining biological degradation of organics by the microbes attached to the BAC. This strategy was implemented at two treatment plants in Sweden. Modified filters showed better removal of humic-like and protein-like NOM fractions than reference filters that did not receive fresh GAC, indicating improved functioning of both adsorption and biological treatment. The result shows that both biodegradation and adsorption mechanism improved within the filters.
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| 7. |
- Sokolova, Ekaterina, 1986, et al.
(författare)
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Fate and transport modelling of microbial pollution in a lake used as a drinking water source
- 2011
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Ingår i: 34th IAHR Congress 2011 - Balance and Uncertainty: Water in a Changing World, Incorporating the 33rd Hydrology and Water Resources Symposium and the 10th Conference on Hydraulics in Water Engineering. - 9780858258686 ; , s. 3271-3278
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Konferensbidrag (refereegranskat)abstract
- Faecal contamination of drinking water sources can cause outbreaks of waterborne disease. In this study a modelling approach is used to investigate the risk of contaminated raw water for the intake to the drinking water treatment plant posed by wastewater discharges in Lake Rådasjön in Gothenburg, Sweden. Microbial pollution is studied using the traditional faecal indicator organism E. coli and virus indicator somatic coliphages. Transport of faecal indicators is simulated using the three-dimensional hydrodynamic model MIKE3, and inactivation processes are described by the ecological module ECOLab. The ecological model is calibrated against decay curves obtained from microcosm experiments with lake water performed under natural conditions. The risks on drinking water supply and critical hydrometeorological situations that can cause low quality of raw water have been identified. This information provides input for further risk assessment of the entire drinking water supply system.
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| 8. |
- Sokolova, Ekaterina, 1986, et al.
(författare)
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Microbial risk assessment of drinking water based on hydrodynamic modelling of pathogen concentrations in source water
- 2015
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 526, s. 177-186
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Tidskriftsartikel (refereegranskat)abstract
- Norovirus contamination of drinking water sources is an important cause of waterborne disease outbreaks. Knowledge on pathogen concentrations in source water is needed to assess the ability of a drinking water treatment plant (DWTP) to provide safe drinking water. However, pathogen enumeration in source water samples is often not sufficient to describe the source water quality. In this study, the norovirus concentrations were characterised at the contamination source, i.e. in sewage discharges. Then, the transport of norovirus within the water source (the river Gota alv in Sweden) under different loading conditions was simulated using a hydrodynamic model. Based on the estimated concentrations in source water, the required reduction of norovirus at the DWTP was calculated using quantitative microbial risk assessment (QMRA). The required reduction was compared with the estimated treatment performance at the DWTP. The average estimated concentration in source water varied between 4.8 x 10(2) and 7.5 x 10(3) genome equivalents L-1; and the average required reduction by treatment was between 7.6 and 8.8 Log(10). The treatment performance at the DWTP was estimated to be adequate to deal with all tested loading conditions, but was heavily dependent on chlorine disinfection, with the risk of poor reduction by conventional treatment and slow sand filtration. To our knowledge, this is the first article to employ discharge-based QMRA, combined with hydrodynamic modelling, in the context of drinking water. (C) 2015 Elsevier B.V. All rights reserved.
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| 9. |
- Åström, Johan, 1977, et al.
(författare)
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Incorporating Expert Judgments in Utility Evaluation of Bacteroidales qPCR Assays for Microbial Source Tracking in a Drinking Water Source
- 2015
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:3, s. 1311-1318
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Tidskriftsartikel (refereegranskat)abstract
- Several assays for the detection of host-specific genetic markers of the order Bacteroidales have been developed and used for microbial source tracking (MST) in environmental waters. It is recognized that the source-sensitivity and source-specificity are unknown and variable when introducing these assays in new geographic regions, which reduces their reliability and use. A Bayesian approach was developed to incorporate expert judgments with regional assay sensitivity and specificity assessments in a utility evaluation of a human and a ruminant-specific qPCR assay for MST in a drinking water source. Water samples from Lake Radasjon were analyzed for E. coli, intestinal enterococci and somatic coliphages through cultivation and for human (BacH) and ruminant-specific (BacR) markers through qPCR assays. Expert judgments were collected regarding the probability of human and ruminant fecal contamination based on fecal indicator organism data and subjective information. Using Bayes formula, the conditional probability of a true human or ruminant fecal contamination given the presence of BacH or BacR was determined stochastically from expert judgments and regional qPCR assay performance, using Beta distributions to represent uncertainties. A web-based computational tool was developed for the procedure, which provides a measure of confidence to findings of host-specific markers and demonstrates the information value from these assays.
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