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  1. Article: Data-driven models for predicting microbial water quality in the drinking water source using E. coli monitoring and hydrometeorological data

    Sokolova, Ekaterina / Ivarsson, Oscar / Lillieström, Ann / Speicher, Nora K. / Rydberg, Henrik / Bondelind, Mia

    Science of the total environment. 2022 Jan. 01, v. 802

    2022  

    Abstract: Rapid changes in microbial water quality in surface waters pose challenges for production of safe drinking water. If not treated to an acceptable level, microbial pathogens present in the drinking water can result in severe consequences for public health. ...

    Abstract Rapid changes in microbial water quality in surface waters pose challenges for production of safe drinking water. If not treated to an acceptable level, microbial pathogens present in the drinking water can result in severe consequences for public health. The aim of this paper was to evaluate the suitability of data-driven models of different complexity for predicting the concentrations of E. coli in the river Göta älv at the water intake of the drinking water treatment plant in Gothenburg, Sweden. The objectives were to (i) assess how the complexity of the model affects the model performance; and (ii) identify relevant factors and assess their effect as predictors of E. coli levels. To forecast E. coli levels one day ahead, the data on laboratory measurements of E. coli and total coliforms, Colifast measurements of E. coli, water temperature, turbidity, precipitation, and water flow were used. The baseline approaches included Exponential Smoothing and ARIMA (Autoregressive Integrated Moving Average), which are commonly used univariate methods, and a naive baseline that used the previous observed value as its next prediction. Also, models common in the machine learning domain were included: LASSO (Least Absolute Shrinkage and Selection Operator) Regression and Random Forest, and a tool for optimising machine learning pipelines – TPOT (Tree-based Pipeline Optimization Tool). Also, a multivariate autoregressive model VAR (Vector Autoregression) was included. The models that included multiple predictors performed better than univariate models. Random Forest and TPOT resulted in higher performance but showed a tendency of overfitting. Water temperature, microbial concentrations upstream and at the water intake, and precipitation upstream were shown to be important predictors. Data-driven modelling enables water producers to interpret the measurements in the context of what concentrations can be expected based on the recent historic data, and thus identify unexplained deviations warranting further investigation of their origin.
    Keywords Escherichia coli ; environment ; hydrometeorology ; model validation ; models ; prediction ; public health ; rivers ; turbidity ; water flow ; water quality ; water temperature ; Sweden
    Language English
    Dates of publication 2022-0101
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2021.149798
    Database NAL-Catalogue (AGRICOLA)

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  2. Article ; Online: Data-driven models for predicting microbial water quality in the drinking water source using E. coli monitoring and hydrometeorological data.

    Sokolova, Ekaterina / Ivarsson, Oscar / Lillieström, Ann / Speicher, Nora K / Rydberg, Henrik / Bondelind, Mia

    The Science of the total environment

    2021  Volume 802, Page(s) 149798

    Abstract: Rapid changes in microbial water quality in surface waters pose challenges for production of safe drinking water. If not treated to an acceptable level, microbial pathogens present in the drinking water can result in severe consequences for public health. ...

    Abstract Rapid changes in microbial water quality in surface waters pose challenges for production of safe drinking water. If not treated to an acceptable level, microbial pathogens present in the drinking water can result in severe consequences for public health. The aim of this paper was to evaluate the suitability of data-driven models of different complexity for predicting the concentrations of E. coli in the river Göta älv at the water intake of the drinking water treatment plant in Gothenburg, Sweden. The objectives were to (i) assess how the complexity of the model affects the model performance; and (ii) identify relevant factors and assess their effect as predictors of E. coli levels. To forecast E. coli levels one day ahead, the data on laboratory measurements of E. coli and total coliforms, Colifast measurements of E. coli, water temperature, turbidity, precipitation, and water flow were used. The baseline approaches included Exponential Smoothing and ARIMA (Autoregressive Integrated Moving Average), which are commonly used univariate methods, and a naive baseline that used the previous observed value as its next prediction. Also, models common in the machine learning domain were included: LASSO (Least Absolute Shrinkage and Selection Operator) Regression and Random Forest, and a tool for optimising machine learning pipelines - TPOT (Tree-based Pipeline Optimization Tool). Also, a multivariate autoregressive model VAR (Vector Autoregression) was included. The models that included multiple predictors performed better than univariate models. Random Forest and TPOT resulted in higher performance but showed a tendency of overfitting. Water temperature, microbial concentrations upstream and at the water intake, and precipitation upstream were shown to be important predictors. Data-driven modelling enables water producers to interpret the measurements in the context of what concentrations can be expected based on the recent historic data, and thus identify unexplained deviations warranting further investigation of their origin.
    MeSH term(s) Drinking Water ; Environmental Monitoring ; Escherichia coli ; Water Microbiology ; Water Quality
    Chemical Substances Drinking Water
    Language English
    Publishing date 2021-08-21
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 121506-1
    ISSN 1879-1026 ; 0048-9697
    ISSN (online) 1879-1026
    ISSN 0048-9697
    DOI 10.1016/j.scitotenv.2021.149798
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Hepatitis E virus genotype 3 strains and a plethora of other viruses detected in raw and still in tap water.

    Wang, Hao / Kjellberg, Inger / Sikora, Per / Rydberg, Henrik / Lindh, Magnus / Bergstedt, Olof / Norder, Heléne

    Water research

    2019  Volume 168, Page(s) 115141

    Abstract: In this study, next generation sequencing was used to explore the virome in 20L up to 10,000L water from different purification steps at two Swedish drinking water treatment plants (DWTPs), and in tap water. One DWTP used ultrafiltration (UF) with 20 nm ... ...

    Abstract In this study, next generation sequencing was used to explore the virome in 20L up to 10,000L water from different purification steps at two Swedish drinking water treatment plants (DWTPs), and in tap water. One DWTP used ultrafiltration (UF) with 20 nm pores, the other UV light treatment after conventional treatment of the water. Viruses belonging to 26 different families were detected in raw water, in which 6-9 times more sequence reads were found for phages than for known environmental, plant or vertebrate viruses. The total number of viral reads was reduced more than 4-log10 after UF and 3-log10 over UV treatment. However, for some viruses the reduction was 3.5-log10 after UF, as for hepatitis E virus (HEV), which was also detected in tap water, with sequences similar to those in raw water and after treatment. This indicates that HEV had passed through the treatment and entered into the supply network. However, the viability of the viruses is unknown. In tap water 10-130 International Units of HEV RNA/mL were identified, which is a comparable low amount of virus. The risk of getting infected through consumption of tap water is probably negligible, but needs to be investigated. The HEV strains in the waters belonged to subtypes HEV3a and HEV3c/i, which is associated with unknown source of infection in humans infected in Sweden. None of these subtypes are common among pigs or wild boar, the major reservoirs for HEV, indicating that water may play a role in transmitting this virus. The results indicate that monitoring small fecal/oral transmitted viruses in DWTPs may be considered, especially during community outbreaks, to prevent potential transmission by tap water.
    MeSH term(s) Animals ; Genotype ; Hepatitis E virus ; Humans ; Phylogeny ; RNA, Viral ; Sweden ; Swine ; Swine Diseases ; Viruses
    Chemical Substances RNA, Viral
    Language English
    Publishing date 2019-09-30
    Publishing country England
    Document type Journal Article
    ZDB-ID 202613-2
    ISSN 1879-2448 ; 0043-1354
    ISSN (online) 1879-2448
    ISSN 0043-1354
    DOI 10.1016/j.watres.2019.115141
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Book ; Thesis: Nonlocal correlations in density functional theory

    Rydberg, Henrik

    (Applied physics report ; 2001,39 ; Doktorsavhandlingar vid Chalmers Tekniska Högskola ; N.S., 1751)

    2001  

    Author's details Henrik Rydberg
    Series title Applied physics report ; 2001,39
    Doktorsavhandlingar vid Chalmers Tekniska Högskola ; N.S., 1751
    Language English
    Size Getr. Zählung [ca. 60 S.]
    Publisher Chalmers Univ. of Technology
    Publishing place Göteborg
    Document type Book ; Thesis
    Thesis / German Habilitation thesis Chalmers Univ. of Technology, Diss.--Göteborg, 2001
    ISBN 9172910682 ; 9789172910683
    Database Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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