| 1. |
- Garmabaki, Amir H. Soleimani, et al.
(författare)
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A Survey on Underground Pipelines and Railway Infrastructure at Cross-Sections
- 2019
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Ingår i: Proceedings of the 29th European Safety and Reliability Conference (ESREL 2019). - Singapore : Research Publishing Services. ; , s. 1094-1101
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Konferensbidrag (refereegranskat)abstract
- Underground pipelines are an essential part of the transportation infrastructure. The structural deterioration of pipelines crossing railways and their subsequent failures are critical for society and industry resulting in direct and indirect costs for all the related stakeholders. Pipeline failures are complex processes, which are affected by many factors, both static (e.g., pipe material, size, age, and soil type) and dynamic (e.g., traffic load, pressure zone changes, and environmental impacts). These failures have serious impacts on public due to safety, disruption of traffic, inconvenience to society, environmental impacts and shortage of resources. Therefore, continuous and accurate condition assessment is critical for the effective management and maintenance of pipeline networks within transportation infrastructure. The aim of this study is to identify failure modes and consequences related to the crossing of pipelines in railway corridors. Expert opinion have been collected through two set of questionnaires which have been distributed to the 291 municipalities in the whole Sweden. The failure analysis revealed that pipe deformation has higher impact followed by pipe rupture at cross-section with railway infrastructure. For underground pipeline under railway infrastructure, aging and external load gets higher ranks among different potential failure causes to the pipeline.
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| 2. |
- Garmabaki, Amir Soleimani, et al.
(författare)
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Underground pipelines and railway infrastructure : failure consequences and restrictions
- 2020
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Ingår i: Structure and Infrastructure Engineering. - : Taylor & Francis. - 1573-2479 .- 1744-8980. ; 16:3, s. 412-430
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Tidskriftsartikel (refereegranskat)abstract
- Underground pipelines are an essential part of the transportation infrastructure. The structural deterioration of pipelines crossing railways and their subsequent failures can entail critical consequences for society and industry, resulting in direct and indirect costs for all the stakeholders involved. Therefore, continuous and accurate condition assessment is critical for the effective management and maintenance of pipeline networks within the transportation infrastructure. The aim of this study has been to identify failure modes and consequences related to pipelines crossing railway corridors. Expert opinions have been collected through interviews and two sets of questionnaires have been distributed to the 291 municipalities in Sweden, with 137 responses in total. The failure analysis has revealed that pipe deformation has the highest impact, followed by pipe rupture at locations where pipelines cross railway infrastructure. For underground pipelines under railway infrastructure, ageing and the external load were awarded a higher ranking than other potential causes of pipeline failure.Authors gratefully acknowledge the funding provided by Sweden’sinnovation agency, Vinnova, through the strategic innovation programmeInfraSweden2030. The funding was granted in a competitiveapplication process that assessed replies to an open call for proposalsconcerning “Condition Assessment and Maintenance of TransportInfrastructure (Grant No. 2016-033113)”.Authors gratefully acknowledge the technical support and collaboration(In-kind support) of Arrsleff R€orteknik at Sweden, Luleå RailwayResearch Center (JVTC), Stormwater&Sewers and the SwedishTransport Administration (Trafikverket). In addition, the authors arethankful to the anonymous referees for their constructive commentsand Dr Matthias Asplund and Dr Masoud Naseri for their support andsuggestions.
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| 3. |
- Hedström, Annelie, 1972-, et al.
(författare)
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Att samordna förnyelse av infrastruktur från strategisk beslutsnivå
- 2023
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Det finns flera nyttor med att samordna förnyelse av VA-ledningar och gator, framförallt när det gäller minskning av kostnader och miljöpåverkan per meter infrastruktur som åtgärdas. Samordningen innebär samtidigt potentiella risker såsom att förkorta livslängden av ledningaroch gator i en för stor omfattning eller att behöva åsidosätta projekt som är nödvändiga för en viss infrastruktur. Ett sätt att arbeta systematiskt med samordning är att införa en strategi som ska följas vid prioritering av förnyelse. De ekonomiska, miljömässiga och sociala effekterna av en sådan strategi kan dock inte uppskattas med nuvarande metoder och verktyg för förnyelseplanering. Därför har en modell för att jämföra samordningsstrategier utvecklats och testats på en fallstudie.
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| 4. |
- Hedström, Annelie, 1972-, et al.
(författare)
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Challenges in water and wastewater transport systems in cold regions
- 2016
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Ingår i: Water and wastewater management – challenges in cold climate.
-
Konferensbidrag (refereegranskat)abstract
- The water and wastewater transport systems faces severe challenges due to climate change, resource constrain and an aging infrastructure. In cold regions the challenges are also related to general conditions societies have in common, e.g. sparsely populated, depopulation, long distances between populated areas and difficulties with recruiting right competence, beside the influence of the harsh climate on the technical system. In Sweden, municipal water services are financed by fees paid by the water utility users in a specific municipality. This means that water utilities in sparsely populated cold regions with on-going depopulation have limited economical resources to operate and maintain the transport and treatment systems for water and wastewater. The objectives of this paper are to illustrate the challenges for managing the transport system by comparing benchmark values for municipalities in cold regions with the Swedish averages, suggest possible measures to meet the challenges and give examples of on-going research in Stormwater&Sewers related to these questions.
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| 5. |
- Hedström, Annelie, 1972-, et al.
(författare)
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Erfarenheter av LTA-system
- 2022
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Hur ser va-branschens erfarenheter av lättryckavloppsystemut? I rapporten presenteras utmaningar och framgångsfaktorerkopplade till dessa LTA-system. Om systemen anläggsoch används på rätt sätt kan de vara ett bra alternativ tillkonventionella självfallssystem, men frågor kring svavelväteoch livscykelkostnader behöver redas ut för att säkerställasystemens långsiktiga hållbarhet.Lättryckavloppssystem (LTA-system) används ofta som alternativ till självfallssystemi omvandlingsområden och där va-huvudmännens verksamhetsområden utvidgas.Under de senaste 20 åren har användningen av LTA-system ökat kraftigt, och i dag ärutbyggnadstakten mycket stor i vissa delar av landet. LTA-system är enklare att anläggai områden med utmanande topografi och markförhållanden, och ledningsgravarnakan göras relativt grunda så att schaktningsbehovet blir mindre än för konventionellasjälvfallsledningar.Genom bättre förståelse för LTA-system finns det stora möjligheter för det svenskava-kollektivet att minska sina investerings- och driftkostnader vid utvidgning av verksamhetsområden, sannolikt med hundratals miljoner kronor de närmaste 20 åren dåbranschen står inför stora investeringar. För att möjliggöra besparingarna behövs deten tydlig helhetsbild av LTA-system och av alla de erfarenheter och den kunskap somfinns. Vilka är framgångsfaktorerna för att lyckas med LTA-system och vad bör mansom va-huvudman akta sig för?Många va-huvudmän har lång erfarenhet av att förvalta LTA-system, medan andraupplever att de behöver mer och bättre underlag innan de kan känna sig trygga attanlägga och förvalta en ny typ av system. Projektet har sammanställt de erfarenhetersom va-huvudmän har av LTA-system. Man har gått igenom litteratur och juridisk praxiskring LTA-system i Sverige, samt genomfört en workshop, en enkät och intervjuer föratt inhämta branschens erfarenheter av LTA i planerings-, bygg- och driftskedena. Vilkautmaningar ser branschen med systemen och var finns det kunskapsluckor? Underprojektets genomförande visade det sig att va-huvudmännen har mycket att lära avvarandra och att erfarenhetsutbyte är viktigt.Resultaten visar att det är viktigt med god planering och anpassning till lokala förhållanden för att lyckas med LTA. Svavelvätebildning är en stor och svårhanterlig fråga.Problemen uppkommer delvis på grund av att det är svårt att planera och dimensionerakorrekt. Ansvarsfrågorna regleras visserligen i lagstiftning men upplevs ändå som svårnavigerade. Det beror på att vissa delar av LTA-systemet är brukarens ansvar och andradelar är va-huvudmannens. Goda relationer mellan fastighetsägare och va-huvudmänär en framgångsfaktor för att säkerställa god funktion hos systemen över tid eftersomLTA ställer högre krav på brukaren än självfallssystemen gör.Frågor som behöver hanteras i fortsättningen är bland annat svavelvätebildning ochsystemens långsiktiga kostnader. Svavelväte är ett stort problem, och samma lösningför att minska svavelväte ger olika resultat på olika platser. Branschen behöver merkunskap och riktlinjer för hur man bäst undviker och avhjälper problemen. De långsiktiga kostnaderna för LTA är oklara och svåra att uppskatta korrekt och planera för. Desamlade livscykelkostnaderna för anläggning, drift och underhåll saknas, och underlagbehöver sammanställas för att man ska kunna ta bättre beslut och skapa mer effektivadriftorganisationer.
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| 6. |
- 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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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Isaksson, Frida, et al.
(författare)
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Evaluating the Use of Alternative Normalization Approaches on SARS-CoV-2 Concentrations in Wastewater: Experiences from Two Catchments in Northern Sweden
- 2022
-
Ingår i: Environments. - : MDPI. - 2076-3298. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- The detection of SARS-CoV-2 RNA fragments in feces has paved the way for wastewater-based epidemiology to contribute to COVID-19 mitigation measures, with its use in a public health context still under development. As a way to facilitate data comparison, this paper explores the impact of using alternative normalization approaches (wastewater treatment plant (WWTP) flow, population size estimates (derived using total nitrogen (TN), total phosphorus (TP) and census data) and pepper mild mottle virus (PMMoV)) on the relationship between viral wastewater data and clinical case numbers. Influent wastewater samples were collected at two WWTPs in Luleå, northern Sweden, between January and March 2021. TN and TP were determined upon sample collection, with RNA analysis undertaken on samples after one freeze–thaw cycle. The strength of the correlation between normalization approaches and clinical cases differed between WWTPs (r ≤ 0.73 or r ≥ 0.78 at the larger WWTP and r ≤ 0.23 or r ≥ 0.43 at the smaller WWTP), indicating that the use of wastewater as an epidemiological tool is context-dependent. Depending on the normalization approach utilized, time-shifted analyses imply that wastewater data on SARS-CoV-2 RNA pre-dated a rise in clinical cases by 0–2 and 5–8 days, for the lager and smaller WWTPs, respectively. SARS-CoV-2 viral loads normalized to the population or PMMoV better reflect the number of clinical cases when comparing wastewater data between sewer catchments.
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| 11. |
- 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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| 12. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Enhancing stormwater treatment through ultrafiltration: impact of cleaning chemicals and backwash duration on membrane efficiency
- 2023
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Ingår i: Water Reuse. - : IWA Publishing. - 2709-6092 .- 2709-6106. ; 13:4, s. 634-646
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Tidskriftsartikel (refereegranskat)abstract
- The effect of chemical cleaning and regular backwashing on the efficiency of an ultrafiltration membrane fouled during stormwater treatment was studied. Increasing backwash time from 30 to 60 s resulted in an increase in productivity by 20%. However, the productivity was highest when a backwash time of 45 s was used (3% higher than using 60 s). Chemical cleaning was carried out using an alkaline solution (NaOH with or without NaOCl) followed by acid washing with HCl. The addition of NaOCl to the cleaning chemical did not significantly increase the efficiency of chemical cleaning, and the average pure water permeability increase was 97 ± 13 LMH bar−1 after chemical cleaning with NaOH followed by HCl and 117 ± 15 LMH bar−1 after chemical cleaning with NaOH + NaOCl followed by HCl, on average. In addition, reversibility after chemical cleaning was 96 ± 67%, on average. The result from scanning electron microscopy showed that at the end of the experiments, inorganic foulants existed in both the inner layer (feed side) and the outer layer (permeate side) of the membrane.
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| 13. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Stormwater treatment using an ultrafiltration membrane and pulsatile fluid flow
- 2023
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Ingår i: Urban Water Journal. - : Taylor & Francis. - 1573-062X .- 1744-9006.
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Tidskriftsartikel (refereegranskat)abstract
- A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from -6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 70 and 91%. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada, Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use.
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| 14. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Stormwater treatment using membrane filtration with pulsatile fluid flow
- 2021
-
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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| 15. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Stormwater treatment using ultrafiltration – Effect of cleaning chemical and backwash time on membrane efficiency
- 2022
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Konferensbidrag (refereegranskat)abstract
- Stormwater runoff is known as one of the main contributors of pollutants which is often discharged untreated to the water bodies and causes environmental risk [1]. Membrane treatment may be a good option for treatment of heavily polluted stormwater as it can also remove small particles and colloids that are not normally captured in typical stormwater facilities such as ponds, wetlands, etc. However, fouling in membranes is challenging to control. Application of a pre-treatment prior to the membrane process might help to postpone fouling [2]. In addition, a proper combination of backwash and chemical cleaning for the membrane is essential but this has not yet been studied specifically for stormwater runoff treatment with membranes. In this study, a combination of ultrafiltration PVP/PES membrane with pulsatile fluid flow was used for separation of pollutants from stormwater. Sieving was considered as pre-treatment. In addition, a combination of backwash and chemical cleaning was used to assess reversibility, flux recovery and productivity of the membrane. The results showed that by increasing backwash time from 30 to 60 s, the reversibility and flux recovery increased from 26% to 75% and 55% to 87%, on average and also resulted in 20% increase in productivity. Cleaning chemically with alkaline solution (NaOH, pH=12), followed by acidic solution (HCl, pH=2), had a good impact on removing foulants from membrane surface. According to the experiments, addition of NaOCl to the alkaline solution did not have significant effect on pure water flux recovery. From environmental point of view, using NaOCl is not recommended [3].
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| 16. |
- Kaykhaii, Saida, 1989-, et al.
(författare)
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Stormwater treatment with ultrafiltration: Characterisation of backwash water : [Traitement des eaux pluviales par ultrafiltration: Caractérisation deseaux de rétrolavage]
- 2023
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Backwash water is an integral part of membrane treatment, normally making up between 2 and 10 % of the clean water production which constitutes a large volume on an industrial scale. To identify suitable treatment or disposal methods for backwash water, it is important to understand the characteristics of the backwash water and what contaminants it contains. In this study, the backwash water from an ultrafiltration membrane process for stormwater treatment was analysed. Concentrations of TSS and TOC were 2.4 and 24 times higher in the backwash water than the influent stormwater. The concentration of particulate and dissolved (<0.45µm) metals in the backwash water was high, for example, the average concentration of total Cu and Cr was 742 ± 215 and 737 ± 243 µg/L. In addition, the average concentration factors for Cu and Cr were 29 ± 9 and 41 ± 15.9. Methods such as coagulation, electrocoagulation and evaporation could be used to further treat backwash water. The residue fraction would contain high concentrations of metals that need to be disposed or could potentially be a good resource for metal recovery in the future.
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| 17. |
- Kaykhaii, Saida, 1989-
(författare)
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Urban Stormwater Treatment with Ultrafiltration and Pulsatile Fluid Flow
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stormwater can be a potential water resource if it is treated, and the quality meets the demand, depending on the application. Various nutrients and pollutants, for example microorganisms can enter stormwater and can vary depending on time and place, as the contaminants come from different sources. Sometimes the quality of stormwater can also deteriorate during its collection and storage. Therefore, the treatment of stormwater could be necessary before reuse and before discharge into the environment. Various treatment methods exist for this purpose. Ponds, wetlands, and bioretention systems are used in various countries to remove pollutants from stormwater. In addition to these methods, the use of membranes for stormwater treatment has become of interest.The application of membrane technology in new areas such as stormwater treatment requires a great deal of research to evaluate the potential opportunities and challenges. Research has been conducted to separate one or a few pollutants from stormwater using membranes. However, more research is needed to evaluate the applicability of using membranes for stormwater treatment, and their challenges and advantages. For this purpose, three experimental studies have been carried out. Polluted snow along a road was collected and treated using an ultrafiltration membrane. To prevent any damages to the membrane, a pretreatment step was included before the membrane process. It was of interest to evaluate the membrane process ability for treating snowmelt and to evaluate the potential for water reuse depending on regulations in different countries. Another objective was to investigate the productivity of the membrane process and try to improve it by adding pulsatile fluid flow to the experimental set-up. To investigate membrane cleaning, backwashing was carried out at regular intervals, and different backwash times and two chemical cleaning combinations were used. In addition, the fouling layer on the membrane was studied using a scanning electron microscope. Afterwards, the quality of the backwash water from the membrane cleaning was analyzed, which may be helpful in the future when looking for a suitable method to recycle the backwash water.When evaluating pulsatile fluid flow, the productivity of the membrane process increased significantly as the frequency of pulses increased (from -6.6 to 82 L/m2/h). The treated snowmelt mixture was of high quality and could be used for various applications, such as wetland maintenance, toilet flushing, and other municipal use. If the treated stormwater is disinfected, it can also be reused as drinking water. In this study, the optimal backwash duration was found to be 45 s in relation to productivity, although the backwash efficiency and permeability were higher with a backwash time of 60 s. The use of chemicals (NaOH with or without NaOCl followed by HCl) could restore the pure water permeability of the membrane to 107 L/m2/h/bar-1, in average. The pure water reversibility after chemical cleaning was 96% on average. Analysis of the backwash water showed that it is a concentrated solution of stormwater pollutants. TOC concentration was 24 times higher than pretreated stormwater. In addition, the backwash water contained significant concentrations of particulate metals and the concentration factor for various metals varied between 15 to 40.
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| 18. |
- Klapp, Rasmus, 1990-, et al.
(författare)
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The French two-stage vertical flow constructed wetland in subarctic climate
- 2022
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Ingår i: 17th International Conference on Wetland Systems for Water Pollution Control: Conference Proceedings. - : IWA Publishing. ; , s. 579-580
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Konferensbidrag (refereegranskat)abstract
- Conventional small wastewater treatment plants in Sweden produce a sludge that needs to be collected and transported long distances to a centralised treatment facility. As many of these small plants are old and need replacement, the question arises weather a more sustainable solution is possible. The French two-stage vertical flow constructed wetland (VFCW) is a method where very little sludge handling is required, as the sludge is treated on-site. Therefore, this study aims to investigate cold climate performance of such a system in northern Sweden. A pilot-scale VFCW was built and sampled for BOD, nutrients and microplastics since November 2021. Results indicate that treatment performance is adequate and that microplastic can also be treated.
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| 19. |
- 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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| 20. |
- Marsalek, Jiri, et al.
(författare)
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Klaffluckor förövervakning av bräddningar
- 2019
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Vanliga klaffluckor i bräddavlopp skulle utan några avancerade instrument kunna användas för att övervaka bräddningar från avloppsledningssystem. Det har visats i ett forskningsprojekt som genomförts inom klustret Dag&Nät där personal från Luleå kommun och forskare vid Luleå tekniska universitet gemensamt har drivit projektet. Med hjälp av vattennivåmätare på vardera sidan om en klafflucka går det att beräkna tryck och flöde. Lösningen är enkel, robust och effektiv när det gäller både drift och kostnader.
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| 21. |
- Mattsson, Jonathan, et al.
(författare)
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Matavfallskvarnar – Långtidseffekter på ledningsnät
- 2015
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Matavfallskvarnar installerade i diskhon som maler ned rester från måltider har stigit i popularitet. Samtidigt finns det en utspridd oro om att den extra belastningen på kommunala ledningsnät i förlängningen kan leda till avloppsstopp. Dag & Nät kan därför tipsa om vår studie om matavfallskvarnars påverkan på ledningsnät som vi genomförde som ett projekt inom ramen för Svenskt Vatten Utveckling. Studien belyser bland annat att kvarnarna inte klarar av att finfördela vissa typer av matrester, exempelvis äggskal, dessa ansamlas istället i ledningar med svackor och dålig lutning.
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| 22. |
- 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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| 23. |
- Milovanovic, Ivan, 1990-, et al.
(författare)
-
Enhancing stormwater sediment settling at detention pond inlets by a bottom grid structure (BGS)
- 2020
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Ingår i: Water Science and Technology. - London, UK : IWA Publishing. - 0273-1223 .- 1996-9732. ; 81:2, s. 274-282
-
Tidskriftsartikel (refereegranskat)abstract
- Stormwater sediments of various sizes and densities are recognised as one of the most important stormwater quality parameters that can be conventionally controlled by settling in detention ponds. The bottom grid structure (BGS) is an innovative concept proposed in this study to enhance removal of stormwater sediments entering ponds and reduce sediment resuspension. This concept was studied in a hydraulic scale model with the objective of elucidating the effects of the BGS geometry on stormwater sediment trapping. Towards this end, the BGS cell size and depth, and the cell cross-wall angle were varied for a range of flow rates, and the sediment trapping efficiency was measured in the model. The main value of the observed sediment trapping efficiencies, in the range from 13 to 55%, was a comparative assessment of various BGS designs. In general, larger cells (footprint 10 × 10 cm) were more effective than the smaller cells (5 × 5 cm), the cell depth exerted small influence on sediment trapping, and the cells with inclined cross-walls proved more effective in sediment trapping than the vertical cross-walls. However, the BGS with inclined cross-walls would be harder to maintain. Future studies should address an optimal cell design and testing in an actual stormwater pond.
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| 24. |
- Milovanovic, Ivan, 1990-, et al.
(författare)
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Performance of a Zeolite Filter treating Copper Roof Runoff
- 2022
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Ingår i: Urban Water Journal. - : Taylor & Francis. - 1573-062X .- 1744-9006. ; 19:5, s. 499-508
-
Tidskriftsartikel (refereegranskat)abstract
- Copper is a common roofing material used in urban environments, yet it poses a threat to the ecosystem. Space requirements for stormwater treatment in urban areas are often problematic. This study investigated the treatment efficiency of a filter system containing zeolite as filter medium and treatment of copper roof runoff in field conditions. Emphasis was placed on copper and zinc treatment, while the release of sodium and aluminium was also evaluated. The filter system was monitored over a period of 16 months (7 sampling events). The filter reduced the total and dissolved copper by 52–82% and 48–85%, respectively. Although the average observed treatment efficiency of copper and zinc was high, considerable decline in filter efficiency was noticed, indicating potential saturation of the filter medium. Moreover, the copper concentrations in the outlet were still high, 350–600 μg/l, and significantly higher than the concentrations recommended by the relevant authorities.
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| 25. |
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| 26. |
- Milovanovic, Ivan, 1990-, et al.
(författare)
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Synthetic stormwater for laboratory testing of filter materials
- 2023
-
Ingår i: Environmental technology. - : Taylor & Francis. - 0959-3330 .- 1479-487X. ; 44:11, s. 1600-1612
-
Tidskriftsartikel (refereegranskat)abstract
- Synthetic stormwater was tested to determine the ageing effects on dissolved metal concentrations and used in a column experiment to determine efficiency of four different filter materials (milkweed, bark, peat, polypropylene) in removing total and dissolved metals. Synthetic stormwater was created by adding metal salts, oil and collected stormwater sediment to tap water. Two ageing experiments were performed to determine the change of synthetic stormwater quality over time. One experiment lasted for 11 days and another focused on rapid concentration changes one day after preparation. The one-day ageing experiment showed rapid decrease in dissolved concentration of certain metals, specifically Cu. To consider this change, correction coefficients for each metal were developed and used to estimate the average dissolved metal concentration in the synthetic stormwater during the experiment to determine filter treatment efficiency. During the 11-day experiment on metal concentrations, no noticeable quality changes were observed for at least six days after the preparation of synthetic stormwater. Furthermore, a column experiment was run with duplicate filter columns. Inflow and outflow samples were analysed for total and dissolved metals, turbidity, particle size distribution, and pH. High removal of total metal concentrations was noticed in all tested filter media (58-94%). Dissolved metal concentration removal varied among different filter media. In general, columns with bark and peat media were able to treat dissolved metals better than polypropylene and milkweed. The level of treatment of dissolved metals between the different filter media columns were bark > peat > milkweed > polypropylene.
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| 27. |
- Milovanovic, Ivan, 1990-, et al.
(författare)
-
Zeolitfilter för avrinning från koppartak
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Koppar används ibland som takmaterial i städer, men det medför problem för miljön. Avrinningen från koppartak är svår att behandla i stadsmiljöer. En ny studie har tittat på hur effektivt ett filtersystem med zeolit som filtermedium kan vara för att minska kopparhalten. Resultaten visar att filtret lyckades minska total och löst koppar med 52–82 % respektive 48–85 %. Trots detta var kopparhalterna i avrinningen fortfarande höga, mellan 350–600 μg/l. Detta överstiger rekommenderade nivåer och indikerar behovet av fortsatt forskning för att förbättra behandlingsmetoderna och minimera miljöpåverkan från koppartak.
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| 28. |
- Nilsson, Andreas, et al.
(författare)
-
Områdesvis förnyelseprioriteringav VA-nät
- 2018
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- För att erhålla ett funktionellt system med acceptabla mängder driftstörningar krävs kontinuerligt underhåll i form av utskiftning av befintliga ledningar där livslängden anses vara förbrukad. Vid driftstörningar kan många kunder temporärt bli utan fungerande vattentillförsel eller avloppssystem. I dagsläget satsar många kommuner på att förnya ledningsnätet, men det kan vara svårt att veta i vilka områden pengarna ska investeras för att få ut maximal samhällsnytta. Därför har en områdesvis prioriteringsmodell tagits fram för att underlätta förnyelseplaneringen.
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| 29. |
- Nyström, Fredrik, 1983-
(författare)
-
Coagulation process characteristics and pollutant removal from urban runoff
- 2019
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many different stormwater control measures (SCMs) can be implemented in order to mitigate issues with polluted stormwater flows into receiving water bodies. The treatment function of SCMs is commonly based on the removal of particles by sedimentation, thereby also removing pollutants associated with particles. In recent years, more attention has been given to characterizing and understanding of different particle size fractions and their association with pollutants commonly found in stormwater. It has become increasingly clear that the smaller sized particles are very important pollutant transporters and should be considered when designing and implementing SCMs. However, the settling velocities for smaller sized particles are very low and may not be effectively removed in existing SCMs. One treatment process with a proven ability to enhance sedimentation is coagulation/flocculation, widespread in water and wastewater treatment, but with very few accounts of it being used in a stormwater context. This thesis aims to investigate the treatability of stormwater with a coagulation/flocculation process. This includes the determination of operating conditions, the dominating coagulation mechanism and the reduction efficiency of stormwater related pollutants. The objectives of the thesis were achieved in laboratory tests treating stormwater in a jar-testing procedure.An initial screening of primary coagulants and flocculant aids was conducted using an urban snowmelt mixture. Five of the chemicals were then selected for an extended testing regime which was setup up to determine the operating conditions where maximal turbidity reduction was attained by measuring the pH, conductivity, alkalinity and zeta-potential over the tested doses for each coagulant. Criteria used for chemical selection included high turbidity reduction, low dose requirement and low pH/alkalinity impacts.Charge reversal was observed at positive zeta-potential indicating that the dominating coagulation mechanism was charge neutralization. The content of turbidity/total suspended solids, total organic carbon, total metals and hydrocarbons by >90%. Dissolved copper was reduced by 40% on average, and the reduction rates for dissolved zinc were varying with up to a 300% increase, presumably due to changes in pH, leading to a higher mobility. Changes in the particle size distribution after coagulation/flocculation as compared to sedimentation indicated an effect on the size fraction corresponding to smaller particles.The performance of the coagulation/flocculation process was also tested on road runoff collected from a central road in Luleå with a high traffic intensity. Two coagulants were tested, iron chloride and pre-hydrolyzed aluminum chloride. Reduction rates for the total metal fraction were >90% on average for both coagulants, but for the dissolved metal fractions differences could be observed between the coagulants with the iron chloride resulting in higher reductions for dissolved chrome (57% compared to 34%) and copper (47% compared to 30%). Both products increased the dissolved fractions of nickel and zinc due to lower final pH.
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| 30. |
- Nyström, Fredrik, 1983-
(författare)
-
Kemisk fällning - en möjlig reningsprocess för dagvatten
- 2023
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Rapport (populärvet., debatt m.m.)abstract
- Dagvatten från starkt förorenade ytor, såsom motorvägar och större vägkorsningar, leds ofta till dagvattendammar eller andra dagvattensystem. Reningseffekten hos dessa system har ett samband med deras area eftersom de har sedimentering som främsta reningsprocess. Urbaniserade områden bebyggs i dag allt tätare och de tillgängliga ytorna för dagvattenhantering är begränsade. Samtidigt blir miljökraven mer stringenta. Då kan det vara svårt att anlägga system som är dimensionerade för att avskilja föroreningarna tillräckligt effektivt. Flera studier har därför fokuserat på hur effekten hos befintliga system kan förstärkas. I rapporten beskrivs hur väl en reningsprocess med kemisk fällning fungerar på förorenat dagvatten.Kemisk fällning är en välkänd process i vattenverk och avloppsreningsverk där den används för att den är mycket effektiv när det gäller att avskilja både partiklar och fosfor. Många föroreningar i dagvatten förekommer i hög grad som partiklar eller är bundna till partiklar. Därför borde en process med kemisk fällning kunna åstadkomma hög avskiljning även för dagvatten. Men det har inte gjorts särskilt många studier på ämnet, och det har inte genomförts någon bredare undersökning av hur processen fungerar för dagvattenrening. Syftet med projektet var därför att undersöka vilka fällningskemikalier som lämpar sig för dagvatten, vad som bör beaktas i en sådan process och hur bra processen kan bli på att avskilja typiska dagvattenföroreningar. Insamlat dagvatten testades under kontrollerade förhållanden på laboratorium. För att utvärdera processen användes dels en snösmältblandning från en plogbank i Luleå, dels vägdagvatten. Det viktigaste resultatet var att reningsgraden blev mycket hög, över 90 procent, för merparten av metallföroreningar och organiska föroreningar. Reningsgraden hade även låg variation, motsvarande cirka en till fem procentenheter. De fällningskemikalier som presterade bäst var kommersiella förhydrolyserade fällningsprodukter. För att erhålla en kemisk fällning är parametrarna pH och alkalinitet viktiga, och vissa dagvatten kan behöva en pH-justering. Kemisk fällning hade även en tydlig effekt på avskiljning av mindre partiklar (<1μm). Vid enbart sedimentering avskildes inte den fraktionen utan hölls i suspension.Resultaten ska bidra till kunskap om kemisk fällning av dagvatten som kan ge verksamhetsutövare en bredare verktygslåda för effektiv dagvattenrening.
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| 31. |
- Nyström, Fredrik, 1983-, et al.
(författare)
-
Laboratory scale evaluation of coagulants for treatment of stormwater
- 2020
-
Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 36
-
Tidskriftsartikel (refereegranskat)abstract
- The treatment effect and process characteristics of coagulation were investigated in semi-synthetic stormwater in laboratory-scale using jar tests. An initial screening of twelve coagulants and flocculant aids was carried out to find a selection of chemicals that efficiently reduced turbidity and suspended solids. Five coagulants were then further investigated with additional parameters measured (conductivity, alkalinity, and ζ-potential). The semi-synthetic stormwater was characterized by a high but variable, particle content, and low alkalinity. In the jar tests, a high treatment efficiency (>90 % reduction of both turbidity and suspended solids) was achieved for all coagulants. For very low alkalinity waters, the use of a biopolymer such as chitosan may be advantageous due to minimal alkalinity consumption. Based on the occurrence of charge reversal for all chemicals investigated, the mechanism for coagulation was likely charge neutralization. Treatment effect occurred in the ζ-potential span of -14 to +1 mV depending on the coagulant used. Initial turbidity and the ζ-potential are interesting parameter candidates for dosing control in stormwater treatment applications.
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| 32. |
- Nyström, Fredrik, 1983-, et al.
(författare)
-
Polymer-assisted hydraulic dredging for quality control of stormwater pond sediment and reject water – Influence of polymer choice and its preparation
- 2023
-
Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 51
-
Tidskriftsartikel (refereegranskat)abstract
- Hydraulic dredging of stormwater ponds may include on-site dewatering of dredged materials using polymersand geotextile filtration. The choice of polymer and its preparation affect the overall operational effectivenessand the quality of the reject water (filtrate) returned to the stormwater pond. This study examined the resultingparticle content as well as nutrient and metal concentrations in the filtrate conducted on hydraulically dredgedstormwater sediment that was chemically conditioned and filtered through geotextile. This study investigateshow polymer choice and preparation affects the outcome. In total, three types of polymers were tested (powder,emulsion commercial cationic polymers and chitosan), the water (tap water or reclaimed) the polymer wasprepared in, and the aging time of the polymer solution. Deviations from manufacturer's instructions on thepolymer preparation increased the amount of polymer needed for an optimal conditioning process. In terms ofpollutant retention, there was no difference between polymer preparations. In the filter cake there was nodiscernable difference between conditioned and unconditioned sediment, rather the difference was noticeable onthe filtrate. Conditioned stormwater sediment produced a geotextile filtrate with considerably less metal andnutrient content than the unconditioned stormwater sediment.
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| 33. |
- Nyström, Fredrik, 1983-, et al.
(författare)
-
Removal of metals and hydrocarbons from stormwater using coagulation and flocculation
- 2020
-
Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 182
-
Tidskriftsartikel (refereegranskat)abstract
- As the understanding of how stormwater pollutants are fractioned and need for mitigation has increased, so has the investigation into more advanced treatment techniques. The present study investigated the treatment efficiency of coagulation/flocculation and sedimentation in semi-synthetic stormwater. Five coagulants were evaluated in terms of reducing particle content, organic carbon, total and dissolved metals, hydrocarbon oil index, and polycyclic aromatic hydrocarbons (PAHs). Changes in the resulting particle size distribution as a consequence of the coagulation treatment were also investigated. The pollutants in the semi-synthetic stormwater were predominantly in the particulate phase. The medium and longer chained hydrocarbons dominated the hydrocarbon oil index, while medium to high molecular weight PAHs were most abundant. Iron chloride was the only coagulant that affected particle size distribution post-treatment, shifting the distribution toward larger particles. In terms of total metal removal, the performance of the coagulants was similar, with over 90% removal on average. Concentration of zdissolved copper, one of the metals found in the dissolved phase, was reduced by 40% via coagulation treatment. The iron chloride coagulant increased dissolved Zn, a change attributed to a considerable drop in pH resulting in higher ion mobility. Similarly, the reduction in organic content (total organic carbon, oil, and PAHs) was over 90% for most coagulants.
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| 34. |
- Nyström, Fredrik, 1983-, et al.
(författare)
-
Removal of metals and hydrocarbons from urban snowmelt by coagulation and flocculation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The treatment efficiency of a coagulation/flocculation and sedimentation process was investigated in urban snowmelt. Five different coagulants were evaluated for their effectiveness in reduction of particle content, organic carbon, total and dissolved metals, hydrocarbon oil index, PAHs and if any changes occurred in the particle size distribution. The pollutants in the snow melt were mostly in the particulate phase, and for both oil index and PAHs characterized by the larger sized molecules. An iron chloride coagulant was the only coagulant that had an effect on the particle size distribution post-treatment, where the distribution was shifted towards larger particles. In terms of total metal removal, the performance for the coagulants were similar with above 90% removal on average. Dissolved Cu, was one of the metals found in the dissolved phase, and it was reduced by 40% by coagulation treatment. The iron chloride coagulant did increase the dissolved Zn, attributed to a larger drop in pH resulting in a higher ion mobility. Similarly, the reduction in organic content, both TOC/oil/PAH were above 90% for most coagulants.
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| 35. |
- Nyström, Fredrik, 1983-, et al.
(författare)
-
Treatment of road runoff by coagulation/flocculation and sedimentation
- 2019
-
Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 79:3, s. 518-525
-
Tidskriftsartikel (refereegranskat)abstract
- A laboratory investigation of the treatment potential of a coagulation process in the context of stormwater treatment was undertaken. The initial 25 L road runoff generated from four rain events was collected and subjected to a jar-testing regime with two commercial coagulants. The treatment effect was assessed by analysing the runoff before and after treatment for turbidity, suspended solids and metal content. The coagulation process resulted in particle and total metal reduction of more than 90% compared to 40% for only sedimentation. Up to 40% reduction of dissolved Cr, Cu and Pb was also observed compared to 0% for sedimentation. This study shows that coagulation may be a useful process for stormwater treatment systems when the treatment requirements are high.
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| 36. |
- Okwori, Emmanuel, 1988-
(författare)
-
Analytics-driven approaches supporting asset management of sanitary sewer networks
- 2024
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Sewer blockages can cause overflows and flooding, with consequences such as damage to property and environmental pollution, risks to public health and economic loss. Despite the causes being understood, blockages in sewer networks may occur unpredictably. The responsible staff for sewer networks at water utilities need to efficiently determine the most effective action (what), the specific network location needing attention (where), the optimal timing for intervention (when), and the appropriate remedial task (how), especially given the unpredictability of blockages. Today a reactive approach to asset management and maintenance is often adopted. Additionally, data availability, quality and interoperability between systems are not always at levels that can support decided objectives, proactive maintenance planning and asset management of pipe networks. Thus, the aim of this thesis is to propose and evaluate approaches that can support analytics-driven maintenance planning and asset management for sewer networks. These approaches aim to contribute to mitigating the impact of siloed data structures and enhance the understanding of blockage root causes from a spatial perspective.In this thesis, the challenges of data management in the asset management of pipe networks were investigated through focus group workshops and questionnaire surveys. A conceptual framework was developed based on findings from focus group workshops and surveys. The framework combines data quality assessments, interoperability evaluations between asset management tools, data collection, and informational benefits analysis. This framework aimed to identify the presence of data silos and plausible pathways towards more data-driven data management strategies. A performance assessment combining performance indicators associated with blockages and partial least squares regression (PLS) was conducted to draw inferences that could be useful at a strategic level. Furthermore, a spatial heterogeneity assessment of blockages and factors affecting blockages was carried out. This approach combined network kernel density estimation (NKDE), network k-function, and geographically weighted Poisson regression (GWPR). Lastly, a vulnerability assessment was carried out that combined topological analysis using edge-based centrality measures and network cross-k-function. These approaches were applied to three sewer networks.The focus group workshops and questionnaire surveys identified several challenges affecting data management in the context of pipe network asset management. Many of the challenges could be ascribed to issues related to data quality and interoperability. Results from the preliminary application of the conceptual framework showed how it could be applied for identifying data silos and pathways to data-driven decision-making towards proactive management blockages in sewers. The observed spatial trends and patterns from network k-function analysis and network kernel density estimation showed spatial variability in the occurrence of blockages (single occurring and recurring). Geographically-weighted Poisson regression analysis showed spatial heterogeneity in factors influencing blockage propensity. The network cross-k-function analysis demonstrated that pipes with historical blockage incidents tend to be clustered around critical pipes with higher centrality values. These results could support vulnerability assessments in sewer networks and the development of targeted maintenance strategies. These approaches together could aid data-informed maintenance planning and asset management at the strategic, tactical and operational levels.
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| 37. |
- Okwori, Emmanuel, 1988-
(författare)
-
Data-driven approaches for proactive maintenance planning of sewer blockage management
- 2021
-
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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| 38. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
-
Data-driven asset management in urban water pipe networks : a proposed conceptual framework
- 2021
-
Ingår i: Journal of Hydroinformatics. - : IWA Publishing. - 1464-7141 .- 1465-1734. ; 23:5, s. 1014-1029
-
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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| 39. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Data integration in asset management of municipal pipe networks in Sweden: Challenges, gaps, and potential drivers
- 2024
-
Ingår i: Utilities Policy. - : Elsevier. - 0957-1787 .- 1878-4356. ; 86
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Tidskriftsartikel (refereegranskat)abstract
- This study involved a survey of Swedish water utilities to evaluate their pipe-network data-collection objectives, usage, storage, and exchange routines. Factors impacting data integration (and the associated benefits) were also identified. Results showed that current data storage and exchange routines can be augmented to support commonly identified objectives and data utilisation needs, especially in larger water utilities. Levels of awareness of the opportunities for and benefits gained through asset management processes and data integration varied between utilities. Further research on the benefits of data integration in pipe network asset management is required to develop an evidence base on benefits accrued in practice, especially considering metadata, the diversity of legacy systems still in operation, costs and policy use.
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| 40. |
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| 41. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Performance assessment of Swedish sewer pipe networks using pipe blockage and other associated performance indicators
- 2019
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Konferensbidrag (refereegranskat)abstract
- Sewer networks are expected to operate with minimal or no interruptions. The complex nature of randomly occurring failures in sewer networks arising from blockages significantly adds to the cost of operation and maintenance. Blockages are significant due to sewage backup or basements flooding, resulting from their occurrence. Continuous performance assessment of sewer pipe networks is necessary to ensure a required level of service at an acceptable cost. This study provides insight into the performance of the sewer pipe networks by assessing the proneness of the network to blockages and drawing inferences at a holistic strategic level of influential explanatory factors of blockage proneness, using data available in the VASS statistics database managed by Swedish Water and Wastewater Association. Results indicate that medium sized municipalities are prone to at least 30% more blockages per km per year compared to other municipalities. A hypothesis of explanatory factors includes, reduced flow volumes and design flow depth resulting in flow velocities below self-cleaning velocity in sewer pipe networks encouraging the sluggishness of flow and increased possibility for sediment deposition and accumulation in sewer leading to blockages. This is also exacerbated by the deposition of non-disposables (wet wipes, baby diapers, hard paper etc.), accumulation of FOGs in sewers and increased water conservation measures. Blockages also show a trend indicating occurrence may have a constant return frequency in medium – less than small sized municipalities.
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| 42. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Performance assessment of Swedish sewer pipe networks using pipe blockage and other associated performance indicators
- 2020
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Ingår i: H2Open Journal. - London : IWA Publishing. - 2616-6518. ; 3:1, s. 46-57
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Tidskriftsartikel (refereegranskat)abstract
- Sewer pipe networks are expected to operate with minimal or no interruptions. The complex nature of randomlyoccurring failures in sewer networks arising from blockages significantly adds to the cost of operation and maintenance.Blockages are significant due to sewage backup or basements flooding, resulting from theiroccurrence. Therefore, continuous performance assessment of sewer pipe networks is necessary to ensurerequired levels of service at an acceptable cost. This study provides insight into the performance of the sewerpipe networks by assessing the proneness of the network to blockages. Furthermore it draws inferences at a holisticstrategic level of influential explanatory factors of blockage proneness, using data available in the SwedishWater and Wastewater Association’s benchmarking system. Results indicate that medium sized municipalitiesare prone to at least 30% more blockages per km per year compared to other municipalities. A hypothesis ofexplanatory factors includes reduced flow volumes and flow depth. Flow velocities below self-cleaning velocityin sewer pipe networks, encouraged by sluggishness of flow are responsible for increased possibility for sedimentdeposition and accumulation in sewers leading to blockages. This is also exacerbated by the deposition of nondisposables(wet wipes, baby diapers, hard paper, etc.), accumulation of fats, oils and grease in sewers andincreased water conservation measures.
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| 43. |
- 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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| 44. |
- Okwori, Emmanuel, 1988-, et al.
(författare)
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Using centrality measures, network cross k-function and geographically weighted regression as decision support for operational issues and redesigning sewers.
- 2022
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Ingår i: 10th International Conference on Sewer Processes and Networks.
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Konferensbidrag (refereegranskat)abstract
- The topology of Sanitary Sewer Networks (SSNs) can play an influential role in the occurrence and magnitude of operational failures such as blockages and basements flooding (Reyes-Silva et al., 2020). For example, meshed (grid-like) topologies are reported to be less vulnerable to failures compared to branched (tree-like) topologies (Zhang et al., 2017). However, in reality, most SSNs are reported to have a predominantly branched topology (Reyes-Silva et al., 2020). Therefore, it could be argued that the spatial behaviour of operational failures may be related to the topological properties of SSNs. This study explored this argument by investigating the spatial association between the location of recurrent blockages and the location of influential nodes within the network. Graph theory–centrality measures (Ganesan et al., 2020) and the network cross-K-function (Okabe and Sugihara, 2012) were the methods used. Secondly, the question of which structural, hydraulic or environmental factors may explain the identified spatial associations was also explored using geographically weighted regression (Fotheringham and Charlton, 2009). In lieu of robust properly calibrated hydraulic models, results from centrality measures and network cross k-function can support the discovery of influential locations within the topology of SSNs that may propagate recurrent blockages. Such influential locations may also be inception points for remedial actions such as redesigning, which may be more cost-effective in the long term compared to conventional approaches like flushing. Results from a preliminary application of centrality measures and network cross-function to the SSN of one municipality (total network length 500 km, ≈40 people/km) using its historical blockage data are presented.
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| 45. |
- Panasiuk, Oleksandr, 1986-, et al.
(författare)
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Ett sätt att upptäckavatten i fel ledning : DTS – Distributed temperature sensing
- 2019
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Det blir många problem för samhälle och miljö när spillvatten är felkopplat till dagvattenledningar, eller när det kommer in tillskottsvatten i spillvattennätet i form av smält snö, dränerings-, grund- eller dagvatten. För att hitta de ledningssträckor eller punkter där de största problemen finns kan man använda metoder som känner av temperaturskillnader mellan spill-, dag- och tillskottsvatten. För smart mätning av temperaturen i avloppsledningar finns en relativt ny metod som mäter kontinuerligt och över långa sträckor – Distributed Temperature Sensing, DTS.
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| 46. |
- Panasiuk, Oleksandr, 1986-, et al.
(författare)
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Identifying sources of infiltration and inflow in sanitary sewers in a northern community: comparative assessment of selected methods
- 2022
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Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 86:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- Infiltration and inflow (I/I) into sanitary sewers causes numerous negative effects on the whole wastewater management system and ultimately, on the receiving waters. Consequently, a number of methods have been developed to analyse the performance of sewer systems with respect to I/I, including: distributed temperature sensing (DTS), closed-circuit television (CCTV) inspections, flow and conductivity measurements, automatic or grab sampling of ammonium, smoke testing, and visual inspection of manholes. Such methods were compared in an application to sanitary sewers in a small community and assessed with respect to their accuracy and ability to identify locations of sources of I/I, as well as temporal and spatial resolutions of the obtained results. Furthermore, different approaches to ammonium sampling during I/I monitoring campaigns were discussed. It was concluded that among the methods tested in this study, DTS had the highest temporal and spatial resolutions, while ammonium grab sampling showed promise for initial screening of large catchments.
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| 47. |
- Panasiuk, Oleksandr, 1986-, et al.
(författare)
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Methods for localization and volume estimation of the infiltration and inflow : Comparative study
- 2017
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Ingår i: 14<sup>th</sup> IWA/IAHR International Conference on Urban Drainage.
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Konferensbidrag (refereegranskat)abstract
- Infiltration and inflow (I/I) into wastewater sewers have numerous negative effects on the whole wastewater system. A number of methods have been developed to estimate performance of sewer system with regards to I/I. This abstract presents and compares selected results of Distributed Temperature Sensing (DTS), Closed-circuit television (CCTV) and ammonium sampling for identifying I/I in wastewater sewers during the snowmelt period, under dry and wet weather conditions. The results showed that different methods produce results that vary in precision, accuracy, time and spatial resolution.
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| 48. |
- Panasiuk, Oleksandr, 1986-, et al.
(författare)
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The feasibility of using flap gates as constriction flow meters for estimating sanitary sewer overflows (SSO)
- 2019
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Ingår i: Desalination and Water Treatment. - : Desalination Publications. - 1944-3994 .- 1944-3986. ; 155, s. 113-119
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Tidskriftsartikel (refereegranskat)abstract
- Increased awareness of the negative effects of sanitary sewer overflow (SSO) events on human health and aquatic life led to the development of various control measures, of which implementation is impeded by the lack of information on SSO occurrences, flows and volumes. The collection of such information requires data acquisition systems, which can be costly and are fully utilized just during limited time periods of the year. In search for inexpensive approaches to SSO monitoring, the feasibility of using existing flap gate installations, serving for prevention of back-up flows into sewers, as constriction flow meters was investigated, with promising results. An experimental pilotscale setup was designed to allow steady water flow through a flap gate built into a partition wall between two chambers. The stabilized water heads in the chambers and the flow rate through the flap gate were measured, for both dry and submerged flap gate conditions, and five flap gate sizes (200, 300, 400, 500 and 600 mm), with relatively heavy covers (6–102 kg). The measured data were used to develop flow rating curves, by non-linear regression, in the form Q = f (ΔH), where Q is the discharge through the flap gate and ΔH is the pressure differential upstream and downstream of the gate. The regression curves fitted the experimental data with high precision (R2 >0.99). The use of flow rating curves for estimation of the SSO volume was discussed. This study demonstrated that the water head measurements upstream and downstream of the flap gate can provide a reliable, accurate and inexpensive method for quantification of the SSO discharges and volumes.
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| 49. |
- Panasiuk, Oleksandr, 1986-, et al.
(författare)
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Using Distributed Temperature Sensing (DTS) for Locating and Characterising Infiltration and Inflow into Foul Sewers before, during and after Snowmelt Period
- 2019
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Ingår i: Water. - : MDPI. - 2073-4441. ; 11:8
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Tidskriftsartikel (refereegranskat)abstract
- Infiltration and inflow (I/I) into sewers cause negative effects on the sewer system,wastewater treatment plant and environment. Identifying the causes and locating the inflows isnecessary in order to address the I/I problem. This paper focuses on using distributed temperaturesensing (DTS) for identifying, locating and characterising I/I into a sewer system during the endof winter–beginning of summer transition period under dry and wet weather conditions. Duringsnowmelt, several locations with I/I were identified, while these locations did not show I/I duringstorm events after the snowmelt. In addition, during a very heavy storm after the snowmelt period,I/I was found at other locations. Therefore, DTS was demonstrated to be effective in identifying thetype of I/I and in locating I/I. Finally, I/I monitoring campaigns in cold climates should take intoaccount the variety of pathways of I/I during snowmelt and during rainfall.
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| 50. |
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