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Søberg, L., Viklander, M., Blecken, G.-T. & Hedström, A. (2019). Reduction of Escherichia coli, Enterococcus faecalisand Pseudomonas aeruginosa in stormwater bioretention: Effect of drying, temperature and submerged zone. Journal of Hydrology X, 3, Article ID 100025.
Open this publication in new window or tab >>Reduction of Escherichia coliEnterococcus faecalisand Pseudomonas aeruginosa in stormwater bioretention: Effect of drying, temperature and submerged zone
2019 (English)In: Journal of Hydrology X, ISSN 2589-9155, Vol. 3, article id 100025Article in journal (Refereed) Published
Abstract [en]

The impact of drying and temperature on the reduction of Escherichia coliEnterococcus faecalis and Pseudomonas aeruginosa in stormwater bioretention systems with and without a submerged zone was assessed using 16 pilot-scale bioretention columns under controlled laboratory conditions. The experimental design enabled analysis of possible interactions between the factors. First outflow and event-based samples were collected. Outflow concentrations were independent of inflow concentrations and hence controlled by internal processes. Overall TSS removal was high but sensitive to bacterial synthesis. Event-based samples had significantly higher bacteria concentrations than first outflow samples, suggesting that remaining/surviving bacteria in the bioretention cells have little effect on initial peak outflow concentrations. The effect of temperature varied between bacterial species and sample types. Long dry periods seemed beneficial for bacteria reduction, but outflow bacteria concentrations peaked during the second watering after long dry periods. Submerged zones significantly reduced bacteria outflow concentrations. However, sudden temperature increases caused bioretention cells with a submerged zone to produce significantly higher bacteria outflow concentrations than before the temperature increase, which was not the case for standard cells. Bioretention cells with submerged zones may thus be poor choices for reducing bacterial concentrations in stormwater runoff in areas experiencing winter conditions. Finally, our results suggest that adsorption (e.g. further enhanced by biofilm formation) is the major mechanism governing bacteria reduction in bioretention systems.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Bacteria, Submerged zone, Stormwater, Bioretention, Winter performance, Wet and dry periods
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73082 (URN)10.1016/j.hydroa.2019.100025 (DOI)
Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2019-03-25Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2019). Treatment of road runoff by coagulation/flocculation and sedimentation. Water Science and Technology
Open this publication in new window or tab >>Treatment of road runoff by coagulation/flocculation and sedimentation
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2019 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732Article in journal (Refereed) Epub ahead of print
Abstract [en]

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.

Place, publisher, year, edition, pages
IWA Publishing, 2019
Keywords
advanced stormwater treatment, coagulation, metals, particles, road runoff, suspended solids
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73090 (URN)10.2166/wst.2019.079 (DOI)
Funder
Swedish Research Council Formas, 2016-20075Swedish Research Council Formas, 2016-01447
Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2019-03-14
Pericault, Y., Kärrman, E., Viklander, M. & Hedström, A. (2018). Data supporting the life cycle impact assessment and cost evaluation of technical alternatives for providing water and heating services to a suburban development in Gällivare Sweden. Data in Brief, 21, 1204-1208
Open this publication in new window or tab >>Data supporting the life cycle impact assessment and cost evaluation of technical alternatives for providing water and heating services to a suburban development in Gällivare Sweden
2018 (English)In: Data in Brief, E-ISSN 2352-3409, Vol. 21, p. 1204-1208Article in journal (Refereed) Published
Abstract [en]

The article presents input data that were used in Pericault et al. (2018) for life cycle impact assessment and total cost assessment of five technical alternatives for heat and water services provision in a suburban development in Sweden. The data consists of a list of environmental impacts (cumulative exergy demand of energy carriers – CExDe, global warming potential – GWP, abiotic depletion potential of elements – ADPE), costs, amortisation periods, lifetimes and output flows of the system processes composing the alternatives. The data was derived from values collected in lifecycle databases, environmental product declarations, scientific publications and personal communications with companies.

Place, publisher, year, edition, pages
Elsevier, 2018
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-71489 (URN)10.1016/j.dib.2018.10.058 (DOI)000457925900164 ()
Available from: 2018-11-07 Created: 2018-11-07 Last updated: 2019-03-08Bibliographically approved
Pericault, Y., Kärrman, E., Viklander, M. & Hedström, A. (2018). Expansion of Sewer, Water and District Heating Networks in Cold Climate Regions: an Integrated Sustainability Assessment. Sustainability, 10(10), Article ID 3743.
Open this publication in new window or tab >>Expansion of Sewer, Water and District Heating Networks in Cold Climate Regions: an Integrated Sustainability Assessment
2018 (English)In: Sustainability, ISSN 2071-1050, E-ISSN 2071-1050, Vol. 10, no 10, article id 3743Article in journal (Refereed) Published
Abstract [en]

This study presents an integrated sustainability assessment of technical alternatives for water and heating services provision in suburban areas affected by a cold climate. Each alternative combines a drinking water supply, sewerage (gravity or low-pressure), pipe freeze protection (deep burial or shallow burial with heat tracing) and heating solution (district heating or geothermal heat pumps). An innovative freeze protection option was considered, in which low-temperature district heating (LTDH) is used to heat trace shallow sewer and water pipes. First, the performance of each alternative regarding seven sustainability criteria was evaluated on a projected residential area in Sweden using a systems analysis approach. A multi-criteria method was then applied to propose a sustainability ranking of the alternatives based on a set of weights obtained from local stakeholders. The alternative with a deep buried gravity sewer and geothermal heat pumps was found to have the highest sustainability score in the case study. In the sensitivity analysis, the integrated trench solution with a gravity sewer, innovative heat tracing and LTDH was found to potentially top the sustainability ranking if geothermal energy was used as the district heating source, or if the weight of the cost criterion increased from 24% to 64%. The study highlights the need for integrated decision-making between different utility providers as an integrated solution can represent sustainability gains.

Keywords
low pressure sewer, low temperature district heating, freeze protection, life cycle assessment, multi-criteria
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-71253 (URN)10.3390/su10103743 (DOI)000448559400385 ()2-s2.0-85055094129 (Scopus ID)
Note

Validerad;2018;Nivå 2;2018-10-30 (svasva)

Available from: 2018-10-18 Created: 2018-10-18 Last updated: 2019-03-08Bibliographically approved
Mattsson, J., Hedström, A., Westerlund, L., Dahl, J., Ashley, R. & Viklander, M. (2018). Impacts on rural wastewater systems in subarctic regions due to changes in inputs from households (ed.). Journal of cold regions engineering, 32(1), Article ID 04017019.
Open this publication in new window or tab >>Impacts on rural wastewater systems in subarctic regions due to changes in inputs from households
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2018 (English)In: Journal of cold regions engineering, ISSN 0887-381X, E-ISSN 1943-5495, Vol. 32, no 1, article id 04017019Article in journal (Refereed) Published
Abstract [en]

The use of water-saving appliances and heat exchangers is becoming increasingly popular to decrease water consumption and recover energy from preheated water. However, such in-household changes can bring particular implications for subarctic rural areas, in terms of solids deposition in sewers and drops in performance of wastewater treatment plants (WWTPs), because these are already experiencing diminishing wastewater flows due to depopulation and seasonal dips in wastewater temperature resulting from infiltration into sewers. Hence, this study has considered two communities in Sweden, postulating three different cases with various scales of retrofitting and usage. The results indicate that the decrease in in-pipe velocities when all households are retrofitted with water-saving appliances could be counteracted by sewer relining, but not by the inclusion of a conventional estimate of infiltration. However, for the case in which retrofitting was combined with decreased usage of the appliances, the decrease in self-cleansing capacity could not be counteracted. The retrofitting of heat exchangers under shower trays in all households did not have a significant effect on treatment processes at the WWTP.

Place, publisher, year, edition, pages
American Society of Civil Engineers (ASCE), 2018
National Category
Water Engineering Energy Engineering
Research subject
Urban Water Engineering; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-14539 (URN)10.1061/(ASCE)CR.1943-5495.0000145 (DOI)000428257200005 ()2-s2.0-85030121882 (Scopus ID)de948167-31d8-4bac-a3d7-ca6af781096b (Local ID)de948167-31d8-4bac-a3d7-ca6af781096b (Archive number)de948167-31d8-4bac-a3d7-ca6af781096b (OAI)
Note

Validerad;2017;Nivå 2;2017-09-25 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-04-20Bibliographically approved
Vidal, B., Herrmann, I., Sharp, L. & Hedström, A. (2018). What are the drivers to decentralize wastewater treatment systems?: A Swedish perspective. In: : . Paper presented at IWA 15th International Specialised Conferences on Small Water and Wastewater Systems, 14-18 October 2018, Haifa, Israel.
Open this publication in new window or tab >>What are the drivers to decentralize wastewater treatment systems?: A Swedish perspective
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Keywords
case study, decentralized sanitation, on-site treatment, small-scale, questionnaire
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-71322 (URN)
Conference
IWA 15th International Specialised Conferences on Small Water and Wastewater Systems, 14-18 October 2018, Haifa, Israel
Available from: 2018-10-24 Created: 2018-10-24 Last updated: 2018-12-13Bibliographically approved
Pericault, Y., Risberg, M., Vesterlund, M., Viklander, M. & Hedström, A. (2017). A novel freeze protection strategy for shallow buried sewer pipes: temperature modelling and field investigation. Water Science and Technology, 76(2), 294-301
Open this publication in new window or tab >>A novel freeze protection strategy for shallow buried sewer pipes: temperature modelling and field investigation
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2017 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 76, no 2, p. 294-301Article in journal (Refereed) Published
Abstract [en]

The burial of sewer and water pipes below the maximum ground frost depth can be very costly and laborious in regions with cold winters. If a freeze protection measure is applied, the utility lines can be installed in a shallower trench to reduce the excavation needs. One freeze protection measure, so called heat tracing, consists in supplying heat along the pipes. In this work, the use of 4th generation district heating as a heat tracing solution was investigated at a pilot site in Kiruna, Sweden. The influence of the system on sewer and water pipe temperatures was studied at a snow-free and snow-covered cross section. To this end, five heat tracing temperatures were tested and the corresponding sewer and water pipe temperatures were measured. The field experiment was also simulated with a two dimensional finite volume model. The study showed that, under the climatic conditions of the experiment, a heat tracing temperature of 25 °C allowed to prevent freezing of the pipes while keeping drinking water pipes in a safe temperature range at both cross sections. The other main result was that the developed finite volume model of the sections showed a good fitting to the experimental data

Place, publisher, year, edition, pages
IWA Publishing, 2017
Keywords
District heating, heat tracing, low temperature, pipe insulation, temperature modelling, utilidor
National Category
Water Engineering Energy Engineering
Research subject
Urban Water Engineering; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-63285 (URN)10.2166/wst.2017.174 (DOI)000406789800006 ()28726696 (PubMedID)2-s2.0-85026329219 (Scopus ID)
Note

Validerad;2017;Nivå 2;2017-08-15 (rokbeg)

Available from: 2017-05-09 Created: 2017-05-09 Last updated: 2019-03-08Bibliographically approved
Pericault, Y., Bruaset, S., Ugarelli, R., Saegrov, S., Viklander, M. & Hedström, A. (2017). Coordinated long term planning of sewer and water mains rehabilitation. In: : . Paper presented at Leading Edge Sustainable Asset Management of Water and Wastewater Infrastructure Conference. Trondheim, Norway, 20-22 June 2017.
Open this publication in new window or tab >>Coordinated long term planning of sewer and water mains rehabilitation
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2017 (English)Conference paper, Published paper (Other academic)
Abstract [en]

Long term planning methodologies for sewer and water mains rehabilitation play a key role in water infrastructure asset management by enabling modelling the influence of renewal strategies on various sustainability indicators. Long term rehabilitation scenarios defining annual replacement rates are typically compared in order to choose the best strategy for the sewer and drinking water network, separately. Another important factor for long term rehabilitation planning is the share of replacement work that will be coordinated with other infrastructures (e.g. water network for the sewer network and vice versa, roads, etc.). This reduces linear replacement costs but also shortens the service life of pipes replaced for coordination reason. The paper proposes an integrated methodology to evaluate the impact of different coordination strategies on future replacement costs for water and sewer networks renewal. The method is applied on a newly built residential area in the town of Gällivare in Sweden.

Keywords
coordination, replacement, road, cohort survival, investments
National Category
Water Engineering
Research subject
Water Resources Engineering
Identifiers
urn:nbn:se:ltu:diva-64912 (URN)
Conference
Leading Edge Sustainable Asset Management of Water and Wastewater Infrastructure Conference. Trondheim, Norway, 20-22 June 2017
Available from: 2017-07-26 Created: 2017-07-26 Last updated: 2017-11-24Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2017). Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation. In: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017. Paper presented at 14th IWA/IAHR International Conference on Urban Drainage, ICUD 2017, Prague, September 10-15 2017.
Open this publication in new window or tab >>Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation
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2017 (English)In: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017, 2017Conference paper, Oral presentation with published abstract (Other academic)
Abstract [en]

This abstract presents a laboratory study of a coagulation/flocculation process on an urban snow melt mixture. Coagulation/flocculation is ubiquitous in water treatment, but has seen little use in the stormwater context. Using a jar-test procedure five different chemicals are evaluated as primary coagulants and their treatment performance on urban snow melt with respect to solids removal and metal content. Particle-size distribution measurements will indicate the process effect on different size fractions in the urban snow melt. Analysis for metal content will show the extent of metal reduction that occurs, either by separating out the particulate fraction or due to precipitation reactions.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-66522 (URN)
Conference
14th IWA/IAHR International Conference on Urban Drainage, ICUD 2017, Prague, September 10-15 2017
Available from: 2017-11-09 Created: 2017-11-09 Last updated: 2017-11-24Bibliographically approved
Herrmann, I., Vidal, B. & Hedström, A. (2017). Slutrapport av projekten "Fosforfällor för små avlopp - hur länge fungerar de?" och "Bakterieutsläpp från små avlopp". Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Slutrapport av projekten "Fosforfällor för små avlopp - hur länge fungerar de?" och "Bakterieutsläpp från små avlopp"
2017 (Swedish)Report (Other academic)
Abstract [sv]

Små enskilda avloppsanläggningar i Sverige består ofta av en slamavskiljare med markbädd eller infiltration. I områden med hög skyddsnivå har på senare år ett stort antal fosforfilter installerats. Syftet med denna studie var att undersöka markbäddars och fosforfilters förmåga att reducera halten bakterier och fosfor i avloppsvattnet. Avloppsanläggningar i Västerbotten, Norrbotten och Norrtälje kommun identifierades och inspekterades. Prover togs mellan september 2015 och september 2016 från tolv avloppsanläggningar, åtta markbäddar och nio fosforfilter. Provtagning skedde minst tre gånger vid varje anläggning, och varje provtagningstillfälle varade cirka 3–4 timmar då det togs två stickprover från slamavskiljarens tredje kammare alternativt från fördelningsbrunnen, samt två flödesproportionella samlingsprover efter den biologiska reningen (det vill säga efter markbädden eller biosteget i minireningsverket) och efter fosforfiltret. I proverna mättes pH, mängden suspenderat material, temperatur, indikatorbakterier (E. coli, totala koliforma, intestinala enterokocker och Clostridium perfringens/C. perfringens), halten löst och total fosfor, halten löst och totalt organiskt kol (DOC, TOC) samt BOD. Spårämnesförsök genomfördes i tre fosforfilter med färgen rhodamin.

 

22 av de 34 inspekterade avloppsanläggningarna (65 procent) lämpade sig inte för flödesproportionell provtagning, vilket visar på svårigheten med att kontrollera funktionen av små avloppsanläggningar med hjälp av provtagning. Nio av 21 inspekterade fosforfilter lämpade sig inte för provtagning på grund av att det inte fanns något vattenflöde genom filtret, vilket indikerar att filtren inte fungerade som avsett.

 

I utloppen från tre av de åtta undersökta markbäddarna var medelkoncentrationen intestinala enterokocker högre än badvattendirektivets gränsvärde för inlandsvatten med utmärkt vattenkvalitet. För E. coli-koncentrationer var detta fallet bara i en enda markbädd, men detta trots att det utgående vattnet var klart och hade TOC koncentrationer på en acceptabel nivå. Det här visar att bakteriekoncentrationer kan vara höga även om markbädden ser ut att fungera.

 

Efter de nio undersökta fosforfiltren var bakteriekoncentrationen särskilt hög efter fosforfilter utan markbädd som förbehandlingssteg. I flera fall översteg koncentrationerna gränsvärdet för utmärkt badvattenkvalitet enligt badvattendirektivet; i tre fosforfilter med avseende på E. coli och i fyra fosforfilter med avseende på intestinala enterokocker. Medelkoncentrationen av E. coli-bakterier reducerades signifikant (p = 0,044) i fosforfiltren, vilket tyder på att fosforfilter kan tjäna som ett reningssteg som ytterligare reducerar bakterier. Detta kunde dock inte påvisas för intestinala enterokocker, totala koliforma eller C. perfringens. Koncentrationen av koliforma bakterier var beroende av fosforfiltrets hydrauliska belastning, vilket tyder på att flödesregimen och vattnets uppehållstid i filtret är viktiga parametrar som påverkar bakteriereduktionen. Både för markbäddarna och för fosforfiltren fanns ett samband mellan koncentrationen av indikatorbakterierer och utloppskoncentrationen av TOC och DOC, vilket tyder på att en högre halt av organiskt kol i utgående vatten visar på en sämre bakteriereduktion.

 

Två av de åtta undersökta markbäddarna visade på god fosforreduktion som uppgick till 70 procent (slamavskiljare exkluderad) vilket krävs vid normal skyddsnivå enligt nuvarande regelverk. Fosforreduktionen i tre andra markbäddar var lägre (21–29 procent). Övriga tre markbäddar kunde inte betraktas vara godtagbara reningsanläggningar eftersom det troligtvis skedde en betydande inströmning av vatten in i dessa markbäddar med utspädning som följd.

 

Den högsta koncentrationen av fosfor i utgående vatten från en markbädd var omkring 15 mg/l. Dock var utgående fosforkoncentrationer från de undersökta markbäddarna endast i fyra av åtta fall så höga (>2mg/l) att ett efterföljande fosforfilter skulle vara meningsfullt. Därför är det viktigt att markbäddar med efterföljande rening i fosforfilter byggs med tätskikt för att undvika in- och exfiltration.

 

Fem av de nio utvärderade fosforfiltren reducerade (tillsammans med den biologiska förbehandlingen) mer än 90 procent av den inkommande fosforn från slamavskiljaren. Det betyder att de klarade reningskravet för fosfor i områden med hög skyddsnivå. Två av filtren uppvisade utgående koncentrationer av totalfosfor på 1–3 mg/l och den högsta utgående medelkoncentrationen var 4,4 mg/l. I anläggningar med biologiska behandlingsenheter som inte var markbäddar stod fosforfiltren för merparten av fosforavskiljningen.

 

Fosforreduktionen i fosforfiltren korrelerade med pH i utgående vatten från filtren, med en beräknad korrelationskoefficient på 74 procent, vilket indikerar att pH kan användas som indikator på filtrets funktion. Dock visade resultaten också att fosforfilter med liknande pH-värde (nära 9) kan skilja sig mycket med avseende på fosforreduktion.

 

Koncentration av organiskt kol eller fosfor i inkommande vatten till fosforfiltren kunde inte korreleras till filtrens fosforreducerade förmåga. En hög hydraulisk belastning påverkade dock fosforfiltrens funktion negativt. Liknande effekt hade filtrets ålder, om än inte lika tydligt. De preliminära resultaten från spårämnesförsöken indikerar att de fosforfilter som hade längre uppehållstid också hade högre fosforavskiljning än filter med kortare uppehållstid.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2017. p. 21
Series
Research report / Luleå University of Technology, ISSN 1402-1528
Keywords
fosforfilter, små avloppsanläggningar, indikatorbakterier, markbädd
National Category
Other Environmental Engineering Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-63307 (URN)978-91-7790-286-7 (ISBN)
Projects
Fosforfällor för små avlopp - hur länge fungerar de?Bakterieutsläpp från små avlopp
Note

Slutrapport av projekt finansierad av Havs- och vattenmyndigheten genom anslag 1:12, Åtgärder för havsochvattenmiljö.

Available from: 2017-05-10 Created: 2017-05-10 Last updated: 2018-12-17Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-9541-3542

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