| 1. |
- Herrmann, Inga, 1978-, et al.
(författare)
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Markbaserad rening - design, funktion och bedömningkriterier vid tillsyn
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Markbaserade reningsanläggningar för avloppsvatten har använts länge i Sverige och anses som en robust och driftsäker reningsmetod. Kommunerna som ansvarar för tillsynen har vid inspektionsbesök av anläggningar observerat olika brister i sådana markbaserade anläggningar, t.ex. förhöjd slamförekomst i slamavskiljare, fördelningsbrunn, spridarledningar och/eller luftningsrör, för höga vattennivåer i delar av anläggningen och/eller problem med ventilation. Dessa problem har också uppmärksammats i olika projekt. Det är dock generellt svårt att bedöma huruvida dessa brister har en negativ påverkan på reningsanläggningens funktion. Det finns ett behov av ökad kunskap om när en markbaserad anläggning fungerar eller inte och hur detta ska bedömas, både för att en anläggning inte ska dömas ut i onödan och för att en anläggning som inte fungerar tillfredsställande får rätt typ av åtgärd.I detta projekt undersöktes design-, funktions- och tillsynsprinciper för markbaserade anläggningar med hjälp av litteraturstudier och intervjuer. Syftet var att bidra till utformning av relevanta bedömningskriterier för markbaserade reningsanläggningar som kan användas vid prövning och tillsyn. Målen var att:- granska litteraturen inom markbaserad rening för att lista viktiga faktorer som påverkar funktionen,- jämföra svenska dimensioneringskriterier för slamavskiljare och infiltrationer med kriterier som används i andra länder (Norge och USA),- beskriva hur tillsyn av markbaserade anläggningar genomförs hos kommuner som är aktiva inom tillsyn,- belysa hur olika kommuner resonerar angående bedömningen av olika typer av brister (i detta mål ingår att bedöma hur allvarliga olika typer av brister är – det vill säga om bristerna kräver en uppföljning i form av föreläggande eller förbud eller om det räcker med information eller enklare uppföljning – och hur pass stor samstämmighet som finns mellan olika kommuner vid bedömning av bristers allvarlighet),- uppmärksamma svårigheter med att bedöma funktionen i markbaserade anläggningar och peka ut framtida områden som behöver vidare arbete, samt att- sammanfatta hur tillsyn bedrivs i andra länder och resonera kring vilka lärdomar som kan dras därur.
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| 2. |
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| 3. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Applicability of using sedimentation and membrane filtration for stormwater treatment
- 2021
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Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid arsenic, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology has shown acceptable treatment ability in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and a membrane process with different pore sizes and pulsatile flow (fluid flow with periodical variation) were evaluated with respect to separation of pollutants from a snowmelt mixture. For the aim of this research work, polyether sulfone nanofiltration and ultrafiltration membranes (PES NF, UF membrane) were used to assess the ability of the overall process to postpone fouling and treat the snowmelt mixture. The variation of pulse frequency was chosen between 0 and 2 Hz. A peristaltic pump with a constant rotational velocity of 220 rpm was used in all the experiments. Sedimentation as pre-treatment method was investigated in pre-experiments and it was shown that a variation in sedimentation time between 0.5-1 hours did not affect the treatment ability of the process. Therefore, 0.5 hour of sedimentation time was chosen in order to reduce the experimental run time. The experimental runs will be carried out during the winter period Feb-April 2021. The concentration of TSS, pH, total and dissolved metals and chloride, as well as the particle size distribution, turbidity and volume of clean water achieved in each experimental run is measured. The results from these experiments will give valuable information about treatment efficiency, if pulsatile flow increases the treatment performance as well as knowledge about the clogging process of the filter.
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| 4. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Stormwater treatment using membrane filtration with pulsatile fluid flow
- 2021
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Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid As, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology is applied in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of the membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and an ultrafiltration membrane process and pulsatile flow were evaluated with respect to separation of pollutants from snowmelt mixture. A bench-scale membrane unit was used with a polyether sulfone ultrafiltration membrane (PES/PVP UF membrane) to assess the efficiency of the process and to evaluate if pulsatile flow at different pulse frequencies (0 and 4 Hz) can postpone fouling. The feed and permeate was sampled and analysed on the concentration of TSS, pH, total and dissolved metals and chloride content, as well as the particle size distribution, TOC, turbidity and oil index. The volume of permeate achieved in each experimental run was monitored. The results from these experiments showed that by increasing pulse frequency from 0 to 4 Hz, the productivity of membrane increased from 13.5% to 65.5%. In addition, TOC removal increased from 70% to 87%. Regardless of pulse frequency the ultrafiltration membrane set-up removed TSS, particles and oil fractions completely. Dissolved As, Cd, Cu, Cr, Ni, Pb and P were reduced by 16, 12.6, 11.8, 23.5, 21, 44 and 73.1%, respectively.
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| 5. |
- Lundy, Lian, et al.
(författare)
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Making Waves : Collaboration in the time of SARS-CoV-2 - rapid development of an international co-operation and wastewater surveillance database to support public health decision-making
- 2021
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 199
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Tidskriftsartikel (refereegranskat)abstract
- The presence of SARS-CoV-2 RNA in wastewater was first reported in March 2020. Over the subsequent months, the potential for wastewater surveillance to contribute to COVID-19 mitigation programmes has been the focus of intense national and international research activities, gaining the attention of policy makers and the public. As a new application of an established methodology, focused collaboration between public health practitioners and wastewater researchers is essential to developing a common understanding on how, when and where the outputs of this non-invasive community-level approach can deliver actionable outcomes for public health authorities. Within this context, the NORMAN SCORE “SARS-CoV-2 in sewage” database provides a platform for rapid, open access data sharing, validated by the uploading of 276 data sets from nine countries to-date. Through offering direct access to underpinning meta-data sets (and describing its use in data interpretation), the NORMAN SCORE database is a resource for the development of recommendations on minimum data requirements for wastewater pathogen surveillance. It is also a tool to engage public health practitioners in discussions on use of the approach, providing an opportunity to build mutual understanding of the demand and supply for data and facilitate the translation of this promising research application into public health practice.
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| 6. |
- Milovanovic, Ivan, 1990-
(författare)
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Components for area-efficient stormwater treatment systems
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With progressing urbanisation, treatment of urban stormwater is a vital issue that should be addressed to ensure good water quality in receiving water bodies. Treatment may be performed near the source, with different filter systems using various filter materials, or by using an end-of-pipe method, e.g. a stormwater pond. One constraint in the urban environment is the lack of available space in developed areas, where stormwater treatment facilities are needed the most. Methods developed to treat the stormwater runoff have been the focus of previous studies but the increasing standards of water quality and increasing land constraint pressures demand the further development of stormwater treatment systems. Both laboratory and field experiments are necessary to understand and improve the treatment processes as well as to evaluate how the implemented methods perform under field conditions. The aim of the thesis was to increase the knowledge about the components in stormwater treatment systems that can be used in area-efficient treatment facilities. In order to compare four potential stormwater filter materials (peat, bark, air-blown polypropylene and milkweed), column experiments were carried out using synthetic stormwater that simulated road runoff. Experiments were carried out to evaluate the impacts of the ageing of synthetic stormwater quality during laboratory testing, including dissolved metal concentrations and their impact on the estimation of filter efficiency. In a field study, a full-scale application of a zeolite filter installation was investigated, with a focus on service life and the efficiency of treating copper roof runoff. In order to further investigate a novel sedimentation device, a bottom grid structure (BGS), promoting sediment settling in a smaller area of a stormwater pond, a hydraulic modelling study was conducted to investigate the impact of the cell geometry of the structure on sediment settling and the impact of the structure on pond maintenance and sediment resuspension. The column tests of four different filter materials showed that bark and peat had higher treatment efficiency for dissolved metals than milkweed and polypropylene, with the order of efficiency being peat>bark>milkweed>polypropylene. All four of the filter materials showed a total metal reduction of over 70%, which could be due to the separation of particle-bound metals in the columns. The ageing of the synthetic stormwater showed that dissolved metals, particularly copper, decreased in concentration, quite rapidly. During one experiment run, the dissolved copper concentration was reduced to 15% of its initial value. In order to account for the concentration changes an equation was proposed that normalised the concentration of dissolved metal over the duration of the experiment. During the observation period of 16 months, the zeolite installation removed 52% to 82% and 48% to 94% of total and dissolved copper, respectively. However, the effluent concentrations were still high (360-600 μg/l). There was also an indication of the decreasing filter performance over time with a prediction that the treatment level of total copper would drop to approximately 25% by the end of the service life of three years. The hydraulic experiments on a scaled model of a BGS showed that wider cells were on average 13% more efficient in trapping the particles than the narrower variant. The cell wall angle also had an impact (tilted walls added to the sedimentation efficiency), although the applicability of such cell structures can be questioned, as this cell shape may hinder maintenance efforts. It was also hypothesised that the inclusion of the BGS in the pond reduces the area needed for sediment settling, thus making the pond more area-efficient and easier to include in an urbanised setting.
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| 7. |
- Okwori, Emmanuel, 1988-
(författare)
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Data-driven approaches for proactive maintenance planning of sewer blockage management
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blockages have been reported to account for a significant proportion of reported failures in sewer networks. The malfunctioning of the sewer network from blockages and the subsequent disruption to other public services and flooding may constitute a risk to the environment and human health. Due to the complex nature of underground sewer networks, a reactive approach to blockage maintenance is typically employed. However, although proactive maintenance strategies have been developed, both approaches could be expensive and highlight the need to address the problem with analytics-based methods. Although blockage triggering mechanisms may be known, sewer blockages often appear at random. Thus, it is necessary to improve the understanding of the influential mechanisms involved in forming blockages in sewer networks to support its maintenance and guarantee adequate performance levels. The overall aim of this thesis was to contribute with new knowledge, approaches and methods that can support improved proactive maintenance planning of blockages in sewer networks.Various methods to achieve the aim have been investigated in relation to asset management planning levels. At the strategic level, blockages and associated performance indicators were employed in conjunction with Poisson and partial least squares regression to assess the performance of sewer networks, including gaining additional insights. At the tactical and operational levels, a procedure was developed. The procedure combines network k-function, geographically weighted regression and random forest ensembles. The network k-function analysis explains the significance of the spatial variation of blockages. The Geographically weighted Poisson regression (GWPR) investigates the degree of influence of explanatory factors on increased blockage propensity in differentiated segments of the sewer networks. Thirdly, the random forest ensembles was used to predict pipes with blockage recurrence likelihood. A proposed conceptual framework was applied at all asset management levels to assess the state of data-driven integrated asset management (IAM), based on data quality assessments, interoperability evaluations between IAM tools, and data collection and informational benefits analysis. Results from demonstrating the methods with data from the Swedish waters statistical database and three Swedish municipal sewer networks, namely A, B and C, are presented. Blockage related performance indicators showed that the average blockage rate in medium sized networks was 2-3 times the rate in other sewer networks in Sweden. Furthermore, sewer maintenance strategies were suspected to be ineffective, and increased proactive strategies may improve maintenance efficiency. The procedure in networks A, B and C indicated that the clustering of recurrent blockages maybe linked to an increased need for flushing-related maintenance in sewer pipe networks. The degree of influence between investigated factors and increased blockage propensity indicated that these relationships were not global (not the same in all locations) within and between the sewer networks for networks A, B and C. These non-stationary relationships were observed to occur in various forms, i.e. adequate self-cleaning velocity showed positive and negative correlations in different locations. The networks with relatively more substantial spatial clusters of blockages, higher data quality and availability were observed to have a higher mean prediction accuracy. The applied conceptual framework showed that intuitive asset management characterised the current state of blockage management in the municipal sewer network C with medium to good data quality and low interoperability.
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| 8. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Data-driven asset management in urban water pipe networks : a proposed conceptual framework
- 2021
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Ingår i: Journal of Hydroinformatics. - : IWA Publishing. - 1464-7141 .- 1465-1734. ; 23:5, s. 1014-1029
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Tidskriftsartikel (refereegranskat)abstract
- Analytical tools used in infrastructure asset management of urban water pipe networks are reliant on asset data. Traditionally, data required by analytical tools has not been collected by most water utilities because it has not been needed. The data that is collected might be characterised by low availability, integrity and consistency. A process is required to support water utilities in assessing the accuracy and completeness of their current data management approach and defining improvement pathways in relation to their objectives. This study proposes a framework to enable increased data-driven asset management in pipe networks. The theoretical basis of the framework was a literature review of data management for pipe network asset management and its link to the coherence of set objectives. A survey to identify the current state of data management practice and challenges of asset management implementation in five Swedish water utilities and three focus group workshops with the same utilities was carried out. The main findings of this research were that the quality of pipe network datasets and lack of interoperability between asset management tools was a driver for creating data silos between asset management levels, which may hinder the implementation of data-driven asset management. Furthermore, these findings formed the basis for the proposed conceptual framework. The suggested framework aims to support the selection, development and adoption of improvement pathways to enable increased data-driven asset management in municipal pipe networks. Results from a preliminary application of the proposed framework are also presented.
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| 9. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Spatial heterogeneity assessment of factors affecting sewer pipe blockages and predictions
- 2021
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Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 194
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Tidskriftsartikel (refereegranskat)abstract
- Efficient management of sewer blockages requires increased preventive maintenance planning. Conventional approaches to the management of blockages in sewer pipe networks constitute largely unplanned maintenance stemming from a lack of adequate information and diagnosis of blockage causative mechanisms. This study mainly investigated a spatial statistical approach to determine the influence of explanatory factors on increased blockage propensity in sewers based on spatial heterogeneity. The approach consisted of the network K-function analysis, which provided an understanding of the significance of the spatial variation of blockages. A geographically-weighted Poisson regression then showed the degree of influence that explanatory factors had on increased blockage propensity in differentiated segments of the sewer pipe network. Lastly, blockage recurrence predictions were carried out with Random Forest ensembles. This approach was applied to three municipalities. Explanatory factors such as material type, number of service connections, self-cleaning velocity, sagging pipes, root intrusion risk, closed-circuit television inspection grade and distance to restaurants showed significant spatial heterogeneity and varying impacts on blockage propensity. The Random Forest ensemble predicted blockage recurrence with 60–80% accuracy for data from two municipalities and below 50% for the last. This approach provides knowledge that supports proactive maintenance planning in the management of blockages in sewer pipe networks.
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