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Milovanovic, I., Vojtěch, B., Hedström, A., Herrmann, I., Picek, T., Marsalek, J. & Viklander, M. (2020). Enhancing stormwater sediment settling at detention pond inlets by a bottom grid structure (BGS). Water Science and Technology, 81(2), 274-282
Open this publication in new window or tab >>Enhancing stormwater sediment settling at detention pond inlets by a bottom grid structure (BGS)
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2020 (English)In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 81, no 2, p. 274-282Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
London, UK: IWA Publishing, 2020
Keywords
hydraulic scale modelling, sediment settling, sediment trapping efficiency, stormwater ponds
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-78470 (URN)10.2166/wst.2020.101 (DOI)000529870200008 ()32333660 (PubMedID)2-s2.0-85084030768 (Scopus ID)
Funder
Swedish Research Council Formas, 2016-20075Swedish Research Council Formas, 2016-01447Vinnova, 2017-04390
Note

Validerad;2020;Nivå 2;2020-05-05 (alebob)

Available from: 2020-04-14 Created: 2020-04-14 Last updated: 2020-05-28Bibliographically approved
Broekhuizen, I., Leonhardt, G., Marsalek, J. & Viklander, M. (2020). Event selection and two-stage approach for calibrating models of green urban drainage systems. Hydrology and Earth System Sciences, 24, 869-885
Open this publication in new window or tab >>Event selection and two-stage approach for calibrating models of green urban drainage systems
2020 (English)In: Hydrology and Earth System Sciences, ISSN 1027-5606, E-ISSN 1607-7938, Vol. 24, p. 869-885Article in journal (Refereed) Published
Abstract [en]

The calibration of urban drainage models is typically performed based on a limited number of observed rainfall–runoff events, which may be selected from a larger dataset in different ways. In this study, 14 single- and two-stage strategies for selecting the calibration events were tested in calibration of a high- and low-resolution Storm Water Management Model (SWMM) of a predominantly green urban area. The two-stage strategies used events with runoff only from impervious areas to calibrate the associated parameters, prior to using larger events to calibrate the parameters relating to green areas. Even though all 14 strategies resulted in successful model calibration (Nash–Sutcliffe efficiency; NSE >0.5), the difference between the best and worst strategies reached 0.2 in the NSE, and the calibrated parameter values notably varied. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies reproduced more validation events poorly (NSE <0) than the single-stage strategies, but they also reproduced more events well (NSE >0.5) and performed better than the single-stage strategies in terms of total runoff volume and peak flow rates, particularly when using a low spatial model resolution. The results show that various strategies for selecting calibration events may lead in some cases to different results in the validation phase and that calibrating impervious and green-area parameters in two separate steps in two-stage strategies may increase the effectiveness of model calibration and validation by reducing the computational demand in the calibration phase and improving model performance in the validation phase.

Place, publisher, year, edition, pages
Nicolaus Copernicus University Press, 2020
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-77987 (URN)10.5194/hess-24-869-2020 (DOI)000518136600001 ()2-s2.0-85080893882 (Scopus ID)
Funder
Swedish Research Council Formas, 2015-121
Note

Validerad;2020;Nivå 2;2020-03-06 (svasva)

Available from: 2020-03-06 Created: 2020-03-06 Last updated: 2020-04-23Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2020). Laboratory scale evaluation of coagulants for treatment of stormwater. Journal of Water Process Engineering, 36, Article ID 101271.
Open this publication in new window or tab >>Laboratory scale evaluation of coagulants for treatment of stormwater
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2020 (English)In: Journal of Water Process Engineering, ISSN 2214-7144, Vol. 36, article id 101271Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Stormwater, treatment, coagulation mechanism, sweep floc, charge neutralization, zeta potential
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73088 (URN)10.1016/j.jwpe.2020.101271 (DOI)2-s2.0-85083768623 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-29 (alebob)

Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2020-05-05Bibliographically approved
Lange, K., Österlund, H., Viklander, M. & Blecken, G.-T. (2020). Metal speciation in stormwater bioretention: Removal of particulate, colloidal and truly dissolved metals. Science of the Total Environment, 724, Article ID 138121.
Open this publication in new window or tab >>Metal speciation in stormwater bioretention: Removal of particulate, colloidal and truly dissolved metals
2020 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 724, article id 138121Article in journal (Refereed) Published
Abstract [en]

For comprehensive estimation of the metal treatment efficiency of bioretention systems, information on metal speciation in the stormwater and the effluent is needed. However, so far, most bioretention studies only considered total metal concentrations. Despite their environmental importance, dissolved metals (defined as fractions < 0.45 μm) have only been evaluated in few studies. This study represents the first bioretention study to subdivide the <0.45 μm fraction further by filtration through a 3 kDa ultrafilter (corresponding to appr. 2–3 nm), thus enabling distinction between particulate, colloidal and truly dissolved metals. Higher bioavailability of the truly dissolved fraction has been indicated by previous research, underlining the importance of this study. Since vegetation and salt in stormwater both may be explanatory variables for metal fractionation, these have been added as factors in the utilized full factorial pilot-scale column experiment. While total metal removal was often >95%, detailed fractionation revealed that Cu and (when no salt was added) Zn removal in the <0.45 μm and <3 kDa fractions was significantly lower. Further, mean concentrations of Cu and (in one treatment) Cd in the <0.45 μm effluent fraction did not meet Swedish receiving water quality guidelines. By calculating the particulate, colloidal and truly dissolved fractions, it was shown that bioretention systems affect metal speciation of Cu and Zn. Colloidal and truly dissolved fractions were mostly prevalent in the effluent rather than the influent. Salt affected metal removal mostly negatively. Fractionation was affected by salt mainly in the influent where it increased the concentrations of Cd and Zn in the truly dissolved fraction (no effects on Cu and Pb fractions). In the effluent, Cu and Zn were only slightly affected by salt. Vegetation had mostly no significant effects on metal removal and fractionation. Further integration of detailed metal fractionation into sampling routines in bioretention research is recommended.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Urban stormwater, Stormwater biofilter, Metal fractionation, Metal speciation, Salt, Rain garden
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-78350 (URN)10.1016/j.scitotenv.2020.138121 (DOI)2-s2.0-85082553950 (Scopus ID)
Note

Validerad;2020;Nivå 2;2020-04-06 (alebob)

Available from: 2020-04-06 Created: 2020-04-06 Last updated: 2020-04-08Bibliographically approved
Okwori, E., Viklander, M. & Hedström, A. (2020). Performance assessment of Swedish sewer pipe networks using pipe blockage and other associated performance indicators. H2Open Journal, 3(1), 46-57
Open this publication in new window or tab >>Performance assessment of Swedish sewer pipe networks using pipe blockage and other associated performance indicators
2020 (English)In: H2Open Journal, E-ISSN 2616-6518, Vol. 3, no 1, p. 46-57Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
London: IWA Publishing, 2020
Keywords
benchmarking, wastewater
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-79003 (URN)10.2166/h2oj.2020.027 (DOI)
Projects
Resource efficient and coordinated maintenance and renewal of horizontal water and road assets
Funder
Swedish Research Council Formas, 2018-01178
Note

Godkänd;2020;Nivå 0;2020-05-27 (alebob)

Available from: 2020-05-26 Created: 2020-05-26 Last updated: 2020-05-27Bibliographically approved
Nyström, F., Nordqvist, K., Herrmann, I., Hedström, A. & Viklander, M. (2020). Removal of metals and hydrocarbons from stormwater using coagulation and flocculation. Water Research
Open this publication in new window or tab >>Removal of metals and hydrocarbons from stormwater using coagulation and flocculation
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2020 (English)In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448Article in journal (Refereed) Epub ahead of print
Abstract [en]

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.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Stormwater treatment, Coagulation/flocculation, Pollutant removal, Metals, Hydrocarbons, Treatment efficiency
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-78988 (URN)10.1016/j.watres.2020.115919 (DOI)
Available from: 2020-05-26 Created: 2020-05-26 Last updated: 2020-05-26
Pericault, Y., Risberg, M., Viklander, M. & Hedström, A. (2020). Temperature performance of a heat-traced utilidor for sewer and water pipes in seasonally frozen ground. Tunnelling and Underground Space Technology, 97, Article ID 103261.
Open this publication in new window or tab >>Temperature performance of a heat-traced utilidor for sewer and water pipes in seasonally frozen ground
2020 (English)In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 97, article id 103261Article in journal (Refereed) Published
Abstract [en]

Heat-traced utility corridors (utilidors) can be used in cold regions to install the drinking water and sewer pipes in a shallow trench above the frost depth, thereby limiting excavation needs and the associated economic, social, and environmental costs. Several of these infrastructures were built in the 60s and 70s in Canada, Alaska, Russia, and Norway. More recently, a new type of heat-traced utilidor was built as a pilot project in Kiruna, Sweden to increase the viability of district heating in the area by allowing co-location of all the utility pipes in a shallow trench. Despite several reported cases of undesirably warm drinking water from full-scale projects, previous research efforts on heat-traced utilidors have mainly focused on pipe freeze protection, not on the prevention of excessive temperatures of the drinking water. To ensure comfortable drinking water in terms of taste and smell, an upper temperature limit of 15 °C is usually recommended. The objective of this study was to evaluate the long-term ability of a heat-traced utilidor to maintain sewer temperatures above 0 °C and drinking water temperatures between 0 and 15 °C. Pipe temperatures were measured continuously at two cross sections of a heat-traced utilidor located in Northern Sweden over a period of 22 months. A thermal model, set up and calibrated on the measurements, was used to simulate the impact of extraordinary cold weather conditions on the pipes’ temperatures. The results showed that the utilidor could keep the pipe temperatures within the desired ranges in most cases but that special care should be taken during design to limit drinking water temperatures during the summer.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Drinking water distribution, Drinking water temperature, Sewage collection, Low temperature district heating, Pipe insulation, Freeze protection
National Category
Water Engineering Infrastructure Engineering Energy Engineering
Research subject
Urban Water Engineering; Energy Engineering
Identifiers
urn:nbn:se:ltu:diva-73076 (URN)10.1016/j.tust.2019.103261 (DOI)000514214800034 ()2-s2.0-85077514338 (Scopus ID)
Funder
Vinnova, 2014-04287Swedish Research Council Formas, 2011-1710
Note

Validerad;2020;Nivå 2;2020-01-29 (johcin)

Available from: 2019-03-01 Created: 2019-03-01 Last updated: 2020-04-16Bibliographically approved
Müller, A., Österlund, H., Marsalek, J. & Viklander, M. (2020). The pollution conveyed by urban runoff: A review of sources. Science of the Total Environment, 709, Article ID 136125.
Open this publication in new window or tab >>The pollution conveyed by urban runoff: A review of sources
2020 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 709, article id 136125Article, review/survey (Refereed) Published
Abstract [en]

Urban stormwater and snowmelt pollution contributes significantly to the deterioration of surface waters quality in many locations. Consequently, the sources of such pollution have been studied for the past 50 years, with the vehicular transportation sector and the atmospheric deposition identified early as the major pollution sources. In search for mitigation of this pollution, source controls, besides other measures, were recognised as effective pollution mitigation tools, whose successful implementation requires a good knowledge of pollution sources. Even though great research efforts have been exerted to document specific sources of urban runoff pollution, or specific groups of pollutants present in urban runoff, a comprehensive overview of all known contributing sources is still missing. This review contributes to closing this gap by compiling findings of previous research and critically synthesizing the current knowledge of various stormwater pollution sources. As the emphasis is placed on the sources, the related issues of implications for urban surface water quality and possible source controls for individual sources are touched upon just briefly, where required. The review showed that the atmospheric deposition, vehicular transportation-related activities and metallic building envelopes continue to be among the major pollution sources, which have been studied in a far greater detail than other sources. Furthermore, it was noted that because of the rapid advances in clean manufacturing and pollution control technologies, a large part of the body of data on stormwater quality available in the literature should be considered as historical data, which may no longer describe well the current conditions. Progressing historical data obsolescence, combined with continuing releases of new materials and chemicals, and, in some cases of new substances of potential concern, into the environment, suggests that the identification of important stormwater runoff/snowmelt pollution sources, and the associated pollutants, has been and will remain to be a work in progress.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Urban diffuse pollution, Stormwater quality, Snowmelt quality, Emerging pollutants, Source controls
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-76044 (URN)10.1016/j.scitotenv.2019.136125 (DOI)000512281700076 ()31905584 (PubMedID)2-s2.0-85077051390 (Scopus ID)
Funder
Swedish Research Council Formas, 942 – 2016-73Vinnova, 2016-05176
Note

Validerad;2020;Nivå 2;2020-01-07 (johcin)

Available from: 2019-09-18 Created: 2019-09-18 Last updated: 2020-04-14Bibliographically approved
Müller, A., Österlund, H., Nordqvist, K., Marsalek, J. & Viklander, M. (2019). Building surface materials as sources of micropollutants in building runoff: A pilot study. Science of the Total Environment, 680, 190-197
Open this publication in new window or tab >>Building surface materials as sources of micropollutants in building runoff: A pilot study
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2019 (English)In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 680, p. 190-197Article in journal (Refereed) Published
Abstract [en]

Control of diffuse pollution is critical for achieving good surface water quality status. In this context, pollutant contributions from building materials have received increased attention in recent decades. This study examined the releases of metals, nonylphenols and phthalates from ten common building surface materials (installed in triplicates) into rainwater runoff from six rain events. The highest releases of metals were from copper and zinc sheets (average concentrations of 3090 μg/L Cu and 7770 μg/L Zn respectively), while other metal materials, e.g., Corten weathering steel, exhibited lower releases. PVC roofing released high concentrations of nonylphenols and phthalates (average concentrations of up to 26 μg/L nonylphenols and 455 μg/L Diisononyl phthalate, DINP) which have not been investigated in the earlier studies. Pollutant releases varied between events, likely because of weather conditions and rainfall characteristics. Study findings should be valuable for environmentally responsible applications of the existing building materials and the development of new ones, as well as the investigations and risk assessment of specific pollutants in stormwater.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Building surface materials, Diffuse pollution sources, Metals, Nonylphenols, Phthalates, Stormwater quality
National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73883 (URN)10.1016/j.scitotenv.2019.05.088 (DOI)000468863400019 ()31108449 (PubMedID)2-s2.0-85065712456 (Scopus ID)
Funder
Swedish Research Council Formas, 942 – 2016-73Vinnova, 2016-05176
Note

Validerad;2019;Nivå 2;2019-06-05 (oliekm)

Available from: 2019-05-09 Created: 2019-05-09 Last updated: 2019-09-18Bibliographically approved
Broekhuizen, I., Leonhardt, G., Marsalek, J. & Viklander, M. (2019). Calibration event selection for green urban drainage modelling.
Open this publication in new window or tab >>Calibration event selection for green urban drainage modelling
2019 (English)Manuscript (preprint) (Other (popular science, discussion, etc.))
Abstract [en]

Calibration of urban drainage models is typically performed based on a limited number of observed rainfall-runoff events, which may be selected from a longer time-series of measurements in different ways. In this study, 14 single- and two-stage strategies for selecting these events were tested for calibration of a SWMM model of a predominantly green urban area. The event selection was considered in relation to other sources of uncertainty such as measurement uncertainties, objective functions, and catchment discretization. Even though all 14 strategies resulted in successful model calibration, the difference between the best and worst strategies reached 0.2 in Nash–Sutcliffe Efficiency (NSE) and the calibrated parameter values notably varied. Most, but not all, calibration strategies were robust to changes in objective function, perturbations in calibration data and the use of a low spatial resolution model in the calibration phase. The various calibration strategies satisfactorily predicted 7 to 13 out of 19 validation events. The two-stage strategies performed better than the single-stage strategies when measuring performance using the Root Mean Square Error, flow volume error or peak flow error (but not using NSE); when flow data in the calibration period had been perturbed by ±40 %; and when using a lower model resolution. The two calibration strategies that performed best in the validation period were two-stage strategies. The findings in this paper show that different strategies for selecting calibration events may lead in some cases to different results for the validation period, and that calibrating impermeable and green area parameters in two separate steps may improve model performance in the validation period, while also reducing the computational demand in the calibration phase.

National Category
Water Engineering
Research subject
Urban Water Engineering
Identifiers
urn:nbn:se:ltu:diva-73294 (URN)10.5194/hess-2019-67 (DOI)
Projects
Reliable modeling of green infrastructure in green urban catchments
Funder
Swedish Research Council Formas, 2015-121
Available from: 2019-03-25 Created: 2019-03-25 Last updated: 2020-03-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1725-6478

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