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  • 1.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic and treatment performance of a 19-year old constructed stormwater wetland: Finally maturated or in need of maintenance?2016In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 95, p. 73-82Article in journal (Refereed)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are a commonly used measure for stormwater retention and quality treatment. However, although questions have been raised about the long-term performance of CSWs, only a few studies have targeted this issue and none have evaluated the performance of CSWs more than approximately 5–10 years old. Further, most studies have not examined the development of the long-term performance of CSWs but delivered a snapshot at a certain point of time. The present study investigated the performance of a 19-year-old CSW in Växjö, Sweden, treating stormwater from a 320-ha urban catchment. Besides removal of sediment from the CSW’s forebay, no other maintenance had been conducted. However, regular inspections had been performed. The results of the present sampling campaign were compared to two existing datasets collected at the same CSW after three years of operation in 1997 and nine years of operation in 2003. The CSW was found to provide efficient peak flow reduction and, depending on the event characteristics, also volume reduction. It still treated stormwater effectively: removal of Cd, Cu, Pb, Zn, TSS and TP event mean concentrations were between 89 and 96%, whereas mean concentrations of TN were reduced by 59%. The load removal efficiencies were even higher. Comparative analysis of the three monitoring periods based on the load removal efficiency revealed that the CSW, despite the lack of maintenance, performed more efficiently and stably for most pollutants compared to when newly constructed. This underlines the importance of the establishment and maturation of constructed wetland systems. Overall, the results showed that CSWs are resilient systems, which if designed well and regularly inspected to prevent major issues, can work efficiently for at least two decades.

  • 2.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of stormwater infiltration systems: a field survey2013In: NOVATECH 2013: Planning and Technologies for Sustainable Urban Water Management, 23 - 27 June 2013, Lyon, France., 2013Conference paper (Refereed)
    Abstract [en]

    This paper examined the factors influencing the long-term hydraulic performance of some stormwater infiltration systems (swale and two types of permeable pavements) in Växjö, southern Sweden. The infiltration capacities of 9 permeable pavements and 2 swales sites, all with different ages ranging from 1 year to 14 years, were measured using replicate double ring infiltrometers. The sites were either constructed of swale (2), interlocking concrete pavers (ICP) filled with gravel (2), concrete grid pavers (CGP) filled with gravel (3), or concrete grid pavers (CGP) filled with grass (4). The results of this study showed that the long-term behaviour of the infiltration capacity relies largely on the type and age of the system and the type of joint filling (gravel and grass). Furthermore, the study showed that the 11 year old concrete grid pavers filled with grass had the highest infiltration capacity (4.80 + 2.46 mm/min), whilst the 9 and 14 year old swales had the lowest infiltration capacity (0.10 + 0.00 mm/min).

  • 3.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term treatment efficiency of a constructed stormwater wetland: preliminary results2014Conference paper (Refereed)
    Abstract [en]

    Constructed stormwater wetlands (CSWs) are commonly used in Sweden and worldwide because of their high efficiency in urban stormwater management. However, questions have been raised about the long-term performance of CSWs. This study investigated the performance of a 19-year-old constructed wetland, which was designed to treat the stormwater from a 320-ha catchment located in the city of Växjö, southern Sweden. The system has not been maintained since its construction in 1994. The results of the present study were compared with results obtained from a previous study conducted by Växjö Municipality in 1997. The results showed that the CSW significantly reduced peak flows by 72%. High concentration reductions were found for Cd, Cr, Cu, Zn, Pb, TSS and TP (90, 89, 91, 90, 96, 96 and 86%, respectively). TN concentrations were reduced by 61%. The results indicated that lack of maintenance had no effect on the performance of wetland system during this long period of operation (19 years). In contrast, especially the removal of Cu and nitrogen was enhanced compared to 1997, which may be due to maturing of the system. The results show that CSWs are resilient systems, which (provided that design is sufficient) can work efficiently for at least two decades.

  • 4.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Merriman, Laura S.
    Biological & Agricultural Engineering, North Carolina State University.
    Hunt, William F.
    Biological & Agricultural Engineering, North Carolina State University.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Survey of the operational status of 25 Swedish municipal stormwater management ponds2017In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 143, no 6, article id 05017001Article in journal (Refereed)
    Abstract [en]

    During the past 50 years, wet stormwater ponds have been constructed to reduce negative environmental impacts of urban stormwater discharges on receiving aquatic environments. However, in many jurisdictions there is little information on the current operational status of such ponds and their functioning. This paucity of information prompted a field survey of 25 Swedish municipal stormwater ponds, aged between 3 and 26 years. The pond survey focused on estimating the pond hydraulic loading and efficiency, the state of littoral vegetation, characteristics of bottom sediment in the inlet and outlet zones (sizes and the chemistry), and the overall operational pond status, including the access for maintenance. The hydraulic efficiencies of ponds were estimated for pond footprint shapes and relative locations of the inlets and outlets using literature data. The estimated hydraulic efficiencies correlated well with the pond length-to-width ratios and the ratio of the pond surface area to the impervious area of the runoff contributing catchment (i.e., the hydraulic loading). Littoral vegetation was inspected visually and found to be overgrown at some facilities, which impeded the maintenance access. Benthic sediments in ponds contained silt and clay (&lt;63&#x2009;&#x2009;&#x3BC;m" role="presentation" style="box-sizing: border-box; display: inline; line-height: normal; word-spacing: normal; word-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;"><63  μm<63  μm), sand and gravel fractions, and when compared with the literature data, such sediments appeared relatively coarse. Chemical characteristics of sediments reflected anthropogenic (traffic) activities, but without excessive contamination warranting special disposal requirements. Of the 25 ponds surveyed, four were fenced off and inaccessible to machinery. In fact, the design of these four ponds was such that it made inspection and maintenance very difficult, which may pose potential risks to ponds operation. Fifty-four percent of the investigated ponds were in need of minor maintenance, primarily because of sediment and litter accumulation in their inflow and outflow sections. The fact that the inspection survey revealed relatively few minor issues that could be corrected easily demonstrates the importance of relatively simple regular inspections serving to detect minor problems at an early stage before they would seriously impact pond functioning. The above survey methodology should be helpful for developing similar low-cost surveys in other jurisdictions.

  • 5.
    Al-Rubaei, Ahmed Mohammed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Engström, Malin
    Växjö Municipality.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Effectiveness of a 19-Year Old Combined Pond-Wetland System in Removing Particulate and Dissolved Pollutants2017In: Wetlands (Wilmington, N.C.), ISSN 0277-5212, E-ISSN 1943-6246, Vol. 37, no 3, p. 485-496Article in journal (Refereed)
    Abstract [en]

    This study monitored the stormwater runoff quantity and quality treatment performance of a 6.8 ha 19-year old combined pond-wetland system, located in south Sweden, over one year. The mean volume reductions for 53 storm events for the pond and wetland were 40% and 28%, respectively, while the mean flow reductions were 60% and 76%, respectively. Pollutant concentrations in the influent to the wetland were highly variable. The pond-wetland system could efficiently remove an average of 91%, 80%, 94%, 91%, 83% and 92% of TSS, TP, particulate Cd, Cu, Pb, and Zn, respectively, whereas the removal of particulate and dissolved Ni was highly variable with an average of 67% ± 62% and −5% ± 41%, respectively. The removal of TN, NH4-N and NO3 + NO2-N was highly variable with an average of 45% ± 27%, 12% ± 96% and 45% ± 43%, respectively. These removal percentages are high in comparison to other studies and underline that relatively old systems can also provide efficient treatment. Although the pond accounted for a substantial reduction of pollutant concentration, the wetland significantly enhanced both the treatment performance and the peak flow reduction. This underlines that a combined pond/wetland system is a more beneficial solution than a pond only. The pollutant removal efficiency was significantly influenced by some factors including Antecedent Dry Days, seasonal variations, air temperature, retention times, rainfall depth and duration, and peak rainfall intensity.

  • 6.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Can vacuum cleaning recover the infiltration capacity of a clogged porous asphalt?2012In: WSUD 2012: Water Sensitve Urban Design - 21 - 23 February 2012, Melbourne Cricket Ground : building the water sensitve community, Barton: Institution of Engineers, Australia , 2012Conference paper (Refereed)
    Abstract [en]

    Objective: The main threat for the performance of porous asphalt is clogging leading to decreased infiltration capacity. Thus, we investigated the potential of vacuum cleaning to recover the infiltration capacity of clogged permeable asphalts which have been in use for several decades. The influence of road operation and maintenance measures on the results was discussed.Method: We investigated the hydraulic conductivity (HC) of two roads with porous asphalt in Haparanda and Luleå, Sweden, which had been in use for 28 years and 15 years, respectively. A lack of appropriate maintenance during their operating life had lead to significant clogging and thus malfunction. The roads were vacuum cleaned using a vacuum cleaner/sweeping truck combination. This technology is recommended as a maintenance option for porous asphalt. Before and after the vacuum cleaning, replicate HC measurements were conducted using double-ring infiltrometers.Result: Before vacuum cleaning, mean HC was <0.1mm/min in Haparanda and between 0.4 and 0.8 mm/min in Luleå. After vacuum cleaning, HC increased significantly in Luleå (between 1.1 and 7.1mm/min) while no significant increase was detected in Haparanda. Despite the improvement after vacuum cleaning, HC was still far lower than the initial HC after construction. Reasons for the different results in Haparanda and Luleå were identified; the road winter maintenance was of primary importance.Conclusion: Depending on the extent of clogging, vacuum cleaning has the ability to recover HC of porous asphalt. However, long term behaviour of the HC depends largely on the street maintenance, thus regular appropriate maintenance is preferable.

  • 7.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term performance of a porous asphalt pavement in Luleå, Sweden: preliminary results2011Conference paper (Other academic)
  • 8.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stenglein, Anna Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of porous asphalt pavements in northern Sweden2013In: Journal of irrigation and drainage engineering, ISSN 0733-9437, E-ISSN 1943-4774, Vol. 139, no 6, p. 499-505Article in journal (Refereed)
    Abstract [en]

    The effect of clogging on the long-term infiltration capacity and porosity of two 18- and 24-year-old porous asphalts was examined by using replicate double-ring infiltrometer tests and analyzing asphalt core samples. Tests were carried out to see if high pressure washing and vacuum cleaning could restore the hydraulic performance. The infiltration capacity of the porous asphalts decreased substantially, primarily due to surficial clogging (0.50 +/- 0.26 in Lulea, Sweden, and 0.22 +/- 0.12 in Haparanda, Sweden, compared to initially > 290 mm min(-1)). In Lulea, washing and vacuum cleaning could partially restore the infiltration capacity (3.48 +/- 3.00 mm min(-1)), but in Haparanda, no effect was measured. The porosity was constantly between 16 and 18%. The difference of the long-term behavior and effect of cleaning in Lulea and Haparanda is primarily attributable to different street maintenance, age, and winter maintenance (application of fine gravel and/or sand). Although the infiltration capacity in Lulea was far below initial values, the asphalt still has the capacity to infiltrate an intense design rainfall (100 year average return interval, 15 min duration), underlining that porous asphalt can be a resilient feature also under nonfavorable conditions

  • 9.
    Al-Rubaei, Ahmed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Long-term hydraulic performance of stormwater infiltration systems2015In: Urban Water Journal, ISSN 1573-062X, Vol. 12, no 8, p. 660-671Article in journal (Refereed)
    Abstract [en]

    Despite the common use of stormwater infiltration systems, there is still only limited data available evaluating the long-term hydraulic function of such systems. The hydraulic performance of twelve stormwater infiltration systems (vegetated and unvegetated concrete grid pavers, unvegetated interlocking concrete pavers and grassed swales) was therefore investigated in field and laboratory environments in Växjö, Sweden. The systems investigated had not been subjected to regular maintenance to sustain infiltration capacity. Due to this, and the fact that, for most systems, an inappropriate joint filling material was used and (at the swales) there was severe compaction, most systems showed a reduced infiltration capacity. Despite this, especially the older vegetated systems, were still capable of infiltrating intense design rainfalls. This study showed the influence of some factors (type and age of the system, the type of joint filling material (grass and macadam) and the distance from the edge of the pavement) on the long-term behaviour of the infiltration capacity. In conclusion, there is a significant risk that existing stormwater infiltration systems are not working adequately in praxis. Proper implementation of construction and regular control by the inspecting authority has to be ensured.

  • 10.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Biofiltration technologies for stormwater quality treatment2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Due to high runoff volumes and peak flows, and significant contamination with (inter alia) sediment, metals, nutrients, polycyclic aromatic hydrocarbons and salt, urban stormwater is a major cause of degradation of urban water ways. Since current urban drainage systems, which heavily rely on piped sewer networks, may not be sustainable, attempts are being made to develop and refine sustainable urban drainage solutions, notably in Water Sensitive Urban Design (WSUD) and Low Impact Development (LID) concepts. Promising systems recommended for application in both WSUD and LID are stormwater biofilters (also known as bioretention systems or rain gardens) using vegetated filter media. Besides their capacity to attenuate flows and minimise runoff volumes, stormwater biofilters have proven efficacy for enhancing effluent water quality. Furthermore, they can be aesthetically pleasingly integrated even in dense urban environments. However, there are still gaps in our knowledge of the variability of biofilters' pollutant removal performance, and the factors that affect their performance.In the studies this thesis is based upon, the effects of various ambient factors, stormwater characteristics and modifications of filter design on the removal of metals, nutrients and total suspended solids (TSS) in biofilters, and pollutant pathways through them, have been investigated. For these purposes, standard biofilters and variants equipped with a submerged zone, a carbon source and different filter materials were exposed to varying temperatures and dry periods, dosed with stormwater and snowmelt, and the inflow and outflow concentrations of the pollutants were measured.Although removal percentages were consistently high (>70%), demonstrating that biofilters can reliably treat stormwater, the results show that metal outflow concentrations may vary widely depending on the biofilter design and the ambient conditions. Prolonged drying especially impaired their removal efficiency, but variations in temperature and filter media variations had little effect on metal removal rates. The adverse effects of drying could be mitigated by using a submerged zone, and thus providing a more constant moisture regime in the filters between storm events. Combined with embedded organic matter, the submerged zone especially significantly enhances Cu removal, helping to meet outflow target concentrations. Similarly, installing a mulch layer on top of the filter provides additional sorption capacity, hence metals do not ingress far into the filter and are mainly trapped on/in the top layer by sorption processes and/or mechanical trapping associated with TSS. This leads to significant metal accumulation, which facilitates biofilter maintenance since scraping off the top layer removes high proportions of previously accumulated metals, thus delaying the need to replace the whole filter media. However, removal of accumulated pollutants from the filter media is crucial for successful long-term performance of the filters to ensure that no pollutant breakthrough occurs.Nitrogen removal was found to be more variable than metal removal, and to be adversely affected by temperature increases, leading to high nitrogen leaching in warm temperatures. Phosphorus removal rates were consistently high, since most phosphorus was particle-bound and thus trapped together with TSS. However, in initial stages phosphorus was washed out from the filter media, indicating that filter media that do not have high levels of labile phosphorus should be used to avoid high effluent concentrations. Given that most outflow concentrations were far lower than those in the stormwater, biofilters are appropriate stormwater treatment systems. Dependent on the ambient conditions, the target pollutants and the sensitivity of the recipient, adaptation of the filter design is recommended. Further work is required to investigate the winter performance and improve the reliability of nitrogen removal, which is highly variable.

  • 11.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hunt, William F.
    Department of Biological and Agricultural Engineering, North Carolina State University, Raleigh.
    Al-Rubaei, Ahmed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Lord, William G.
    North Carolina Cooperative Extension, North Carolina State University, Raleigh.
    Stormwater control measure (SCM) maintenance considerations to ensure designed functionality2017In: Urban Water Journal, ISSN 1573-062X, Vol. 14, no 3, p. 278-290Article in journal (Refereed)
    Abstract [en]

    Great investment is made in the design and installation of stormwater control measures (SCMs). Substantial research investment, too, is made to optimise the performance of SCMs. However, once installed, SCMs often suffer from lack of maintenance or even outright neglect. Key maintenance needs for wet ponds, constructed stormwater wetlands, bioretention, infiltration practices, permeable pavement, swales, and rainwater harvesting systems are reviewed with many tasks, such as the cleaning of pre-treatment areas and the preservation of infiltration surfaces, being common maintenance themes among SCMs. Consequences of lacking maintenance are illustrated (mainly insufficient function or failure). Probable reasons for neglect include insufficient communication, unclear responsibilities, lack of knowledge, financial barriers, and decentralised measures. In future designs and research, maintenance (and lack thereof) should be considered. Assessing the performance of SCMs conservatively and including safety factors may prevent consequences of under-maintenance; and requiring regular inspection may help to enforce sufficient maintenance.

  • 12.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Karlsson, Kristin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Closure to “Environmental Risk Assessment of Sediments Deposited in Stormwater Treatment Facilities: Trace Metal Fractionation and Its Implication for Sediment Management”2018In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 144, no 4Article in journal (Refereed)
  • 13.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    National Water Research Institute, Environment Canada.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Laboratory study of stormwater biofiltration in low temperatures: total and dissolved metal removal and fates2011In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 219, no 1-4, p. 303-317Article in journal (Refereed)
    Abstract [en]

    Stormwater biofilters, which are recommended for application in both Water-Sensitive Urban Design and Low Impact Development, can remove up to 80% or 90% of total metals found in stormwater. However, their winter operation is a common concern. That was addressed in this study by investigating the metal removal effectiveness of replicate laboratory biofilter mesocosms at 2°C, 8°C and 20°C. As recommended for cold climate bioretention, coarse filter media were implemented and in the top 100 mm layer topsoil was added to increase the sorption capacity. Cd, Cu, Pb and Zn concentrations measured in the biofilter effluent were far below those in the influent and this significantly improved the treated stormwater quality. Contrary to a common notion that coarse media in the main filter body impair dissolved metal sorption, satisfactory removals of dissolved metals were found in this study with most metal burdens retained in the top layer of the filter in which the sorption capacity was enhanced by topsoil. Some metal uptake by the plants was also detected. Temperature did not affect Cd, Pb and Zn removals in general, but Cu removals increased with decreasing temperatures. This was explained by increased biological activities in the filters at warmer temperatures, which may have led to an increased release of Cu with dissolved organic matter originating from root turnover and decomposition of organic litter and debris. Furthermore, plant uptake and biofilm adsorption may also be influenced by temperature. However, even in the worst case (i.e. at 20°C), Cu was removed effectively from the stormwater. Further research needs were identified including the effects of road salts on stormwater biofiltration during the winter period.

  • 14.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Rentz, Ralf
    Malmgren, Charlotte
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stormwater impact on urban waterways in a cold climate: variations in sediment metal concentrations due to untreated snowmelt discharge2012In: Journal of Soils and Sediments, ISSN 1439-0108, E-ISSN 1614-7480, Vol. 12, no 5, p. 758-773Article in journal (Refereed)
    Abstract [en]

    Purpose: Stormwater discharges include contaminated sediments that accumulate in the receiving water body. It is thus important to investigate sediment and pollutant processes and pathways from the catchment to, and within, the receiving water. These processes may be influenced by seasonal changes. The objective of this study was to investigate the stormwater impact on receiving waters in the Luleå area, Northern Sweden; seasonal changes in contamination loads in the receiving waters due to snowmelt; and factors influencing the pollutant pathways in the receiving waters. Materials and methods: In front of three storm sewer outlets in Luleå, samples of bottom sediment (surface layer 0-2 cm) were collected from the connecting ditches and the downstream water body in autumn and spring (before and after the snow season 2009/2010). The characteristics of the receiving waters differed in geomorphology and vegetation. The sediment was analyzed for loss-on-ignition (LOI), grain size, and bulk concentrations of SiO 2, Al 2O 3, CaO, Fe 2O 3, MnO, Na 2O, P 2O 5, TiO 2, As, Cd, Co, Cr, Cu, Hg, Ni, Pb, S, V, and Zn. The sediment contamination was compared to concentrations at a reference point in Luleå where the bottom sediment was not affected by stormwater discharges and with Swedish environmental quality guidelines. Pearson's correlation and a principal component analysis were used to further evaluate the results. Results and discussion: Relative to the reference point, elevated trace metal concentrations were detected in sediments at all three sampling stations. At two of the stations, seasonal variations in ditch sediment grain size, LOI, and contaminant concentrations were observed, originating from stormwater sediment. Snowmelt runoff caused an increased proportion of fine-grained sediment fractions (<0.063 mm) in spring, mainly due to changes in runoff intensity and high sediment loads in the snowmelt runoff. The retention of metals appeared to be due to low turbulence in the water and the presence of organic material. Conclusions: Stormwater discharge affected the contaminant concentrations in the bottom sediments. The observed seasonal variation of contaminants indicated that relatively high amounts of contaminants are discharged during snowmelt and then reallocated within the receiving water body, either directly or after some temporal retention, depending on the characteristics of the receiving water. A calm water column and the presence of organic material in the receiving water body were crucial for the retention of metals

  • 15.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Tondera, Katharina
    Stormwater Research Group, University of the Sunshine Coast, Maroochydore.
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Metals: Occurrence, Treatment Efficiency and Accumulation Under Varying Flows2018In: Ecotechnologies for the Treatment of Variable Stormwater and Wastewater Flows / [ed] Katharina Tondera, Godecke-Tobias Blecken, Florent Chazarenc, Chris C. Tanner, Cham: Springer, 2018, p. 75-91Chapter in book (Refereed)
    Abstract [en]

    Metals were the first priority pollutants to be widely investigated in stormwater. In solid phase, they are often attached to very fine particles. The dissolved fraction creates considerable environmental problems as it is the most bioavailable fraction. Hence, removal of both fine and dissolved particles plays a major role in the treatment of polluted runoff. Ecotechnologies specifically designed to remove metals should be able to address different treatment mechanisms. However, the exhaustion of sorption capacity reduces the lifespan of treatment facilities. Additionally, metal concentrations fluctuate extremely—spatially, seasonally and over time—which poses another challenge for further increasing removal efficiencies. While soil- or sand-based systems should be designed in a way that the filter material can be exchanged, newer developments such as Floating Treatment Wetlands show promising removal capacities as the installations bind metals in sludge sediments, which can be removed from time to time. The different treatment mechanisms, aforementioned developments and techniques as well as their removal capacities will be discussed in this chapter

  • 16. Blecken, Godecke-Tobias
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Muthanna, Tone M.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Zinger, Yaron
    Monash University, Melbourne, VIC.
    Deletic, Ana
    Monash University, Melbourne, VIC.
    Fletcher, Tim
    Monash University, Melbourne, VIC.
    Biofilter treatment of stormwater: temperature influence on the removal of nutrients2007In: Techniques et stratégies durables pour la gestion des eaux urbaines par temps de pluie: 6e Conférence internationale, [25-27] juin 2007, Lyon, France, Villeurbanne: Graie , 2007Conference paper (Refereed)
    Abstract [en]

    Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source has to be treated in order to reduce its nutrient loads. Biofilters which use media, biofilms and plants, are a good treatment option regarding nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2°C, +8°C, control at +20°C) which may cause special problems regarding the biofilter performance. It was shown that particle bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NOx was produced in the columns which can be explained with both insufficient denitrification and high leaching from the columns.

  • 17. Blecken, Godecke-Tobias
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Svensson, Gilbert
    Hedström, Annelie
    Fat, oil and grease (FOG) in sewer systems: a significant problem in Sweden and Norway2009Conference paper (Other academic)
  • 18.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Svensson, Gilbert
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Fett i avloppsnät: kartläggning och åtgärdsförslag2010Report (Other academic)
    Abstract [en]

    Fat oil and grease (FOG) from food preparation can cause severeproblems if it is discharged to the municipal sewer network. A surveyamong Swedish and Norwegian municipalities has shown that nearlyall respondents experience FOG-related problems. The most commonproblem is FOG accumulation connected to the sewer pipes whichdecreases the pipe pipe capacity and may lead to sewer overflows. FOGaccumulation occurs especially at lift stations and depressions. FOGdeposits are often made up of saponised FOG. The fatty acids promotefurthermore corrosion of concrete pipes. FOG can even impact wastewater treatment and might cause severer working conditions.The aim for the water suppliers has thus to be an effective FOGsource control before FOG is discharged to the sewer network. Sourcesare both commercial establishments and residential sewer customers.In this report different source control measures are discussed. Greaseinterceptors are commonly used for commercial FOG sources. However,a number of them lack a grease interceptor and quite often operationand maintenance is deficient. An insufficient frequency ofemptying and a lack of supervision have been identified as a commonproblem. FOG collection systems for commercial FOG producers existin both Sweden and Norway. Collection systems for private householdsare currently in a test phase and experiences from among others Austriaare promising. Even the collected amount of FOG could presumablybe increased. Collected FOG and FOG slurry from interceptors is avaluable resource which can be used as raw material in the chemicalindustry or as an energy source (combustion, biodiesel, fermentation).Threshold values for FOG discharges are set up commonly by municipalities.However, even here supervision is often insufficient. Often, thethreshold values are inadequately low and a value of at least 150 mg/lis recommended. All those measures have to be supported by informationcampaigns which aim on both commercial and private customers.

  • 19.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Svensson, Gilbert
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Projekt: Fett i avloppsnät - Kartläggning och åtgärdsförslag2010Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Matfett och -olja som släpps ut till avloppsnätet kan orsaka driftproblem. Denna enkätstudie har visat att nästan alla kommuner i Norge och Sverige upplever problem på grund av fettet.

  • 20.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Zinger, Yaron
    Monash University, Melbourne, VIC.
    Deletic, Ana
    Monash University, Melbourne, VIC.
    Fletcher, Tim D.
    Monash University, Melbourne, VIC.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Effect of retrofitting a saturated zone om the performance of biofiltration for heavy metal removal: preliminary results of a laboratory study2010In: NOVATECH 2010: 7th International conference on sustainable techniques and strategies in urban water management, Lyon, France, June 27 - July 1st, 2010, Villeurbanne: Graie , 2010Conference paper (Refereed)
    Abstract [en]

    Stormwater biofilters are a stormwater treatment technology which has been becoming increasingly popular. Recently it has been shown that a submerged zone in the filter media improves the magnitude and consistency of nitrogen treatment. Furthermore, the submerged zone has even been shown to be beneficial for retention of heavy metals, particularly Cu. However, most existing biofilters do not include a saturated zone. Since it is relatively simple to retrofit a submerged zone by elevating the outflow, the effect of such a retrofitting on metal removal was investigated in this laboratory study using biofilter columns. It has been shown that a retrofitted submerged zone has a statistically significant but practically small effect on metal removal: Zn removal is slightly enhanced while the effect on Cu removal is inconsistent. Thus, retrofitting of a submerged zone is not recommended if metals are the main target pollutants. But if a submerged zone would have other benefits (e.g. for nitrogen removal or to protect the system from prolonged drying periods) it can be retrofitted without compromising metal removal.

  • 21. Blecken, Godecke-Tobias
    et al.
    Zinger, Yaron
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Deletic, Ana
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Fletcher, Tim D.
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Impact of a submerged zone and a carbon source on heavy metal removal in stormwater biofilters2009In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 35, no 5, p. 769-778Article in journal (Refereed)
    Abstract [en]

    Biofilters are an effective treatment option for the substantial heavy metal loads in urban stormwater. However, to increase their nitrogen treatment efficacy, the introduction of a submerged (anoxic) zone (SZ) and a cellulose based carbon source (C) has been recommended because it has been shown to enhance denitrification and thereby increase overall nitrogen removal. To examine the impact of this design modification on heavy metal treatment, a laboratory study using biofilter mesocosms with different levels of SZ and with or without added C was conducted. The results show that SZ and C have a significant impact on metal treatment. In particular, the removal of Cu was improved significantly. The presence of SZ and C allows outflow Cu concentrations to meet Swedish and Australian water quality guidelines, which are not met with a standard biofilter without SZ or C. Although Zn and Pb removal was enhanced slightly by the presence of a SZ, this improvement is of less practical importance, since Zn and Pb removal is already very high (>95%) in standard biofilters. The best metal treatment was achieved with 450 and 600 mm SZ. Based on these results, the incorporation of SZ with C in stormwater biofilters is recommended.

  • 22.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Zinger, Yaron
    Monash University, Melbourne, VIC.
    Deletic, Ana
    Monash University, Melbourne, VIC.
    Fletcher, Tim D
    Monash University, Melbourne, VIC.
    Viklander, Maria
    Laboratory studies on metal treatment efficiency of stormwater biofilters2010Conference paper (Other academic)
    Abstract [en]

    Stormwater biofilters are a reliable technology to remove metals from stormwater. A solid carbon source in the filter (combined with a submerged zone) enhances especially Cu removal further; the already high Pb and Zn removal is slightly enhanced. However, the submerged zone helps to minimize (Cu, Zn) or eliminate (Pb) the negative effects which prolonged drying has on the removal rates. Thus, the introduction of a submerged zone is only recommended if nitrogen treatment is targeted (Zinger et al. 2007) or if drying is expected. Temperature differences might have a little influence on especially Cu treatment. However, this influence is not of practical importance indicating that biofilters can successfully be implemented throughout the whole seasonal cycle. A high proportion of metals are retained at the top of the filter which is important for biofilter design and maintenance planning. A filter less than the currently recommended 800 to 900 mm might be sufficient for reliable metal treatment. Furthermore, scraping of the top layer could delay replacing of the whole filter media

  • 23.
    Blecken, Godecke-Tobias
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Zinger, Yaron
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Deletic, Ana
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Fletcher, Tim
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Hedström, Annelie
    Viklander, Maria
    Laboratory study on stormwater biofiltration: nutrient and sediment removal in cold temperatures2010In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 394, no 3-4, p. 507-514Article in journal (Refereed)
    Abstract [en]

    Stormwater biofilters have the ability to remove nutrients from stormwater. Reliable pollutant removal during the cold season is particularly important due to the comparably high contamination levels. However, the removal performance might be negatively affected by low temperatures. A biofilter column study was conducted in thermostat-controlled climate rooms (at 2, 7 and 20 °C) to investigate the effect of low temperatures on nutrient removal. Phosphorus and suspended solids removal were significantly correlated and consistently very high (typically in excess of 90 and 95%, respectively, at all temperatures). This is important for the successful implementation of biofilters in cold climates since phosphorus is commonly of principal concern, often being the limiting factor for eutrophication in freshwater ecosystems. Unfortunately, nitrogen removal was poor and leaching was shown, which increased with temperature. The increasing nitrate-nitrogen production rates with temperature were well described by the Arrhenius relationship with temperature coefficients Q10 in the range which is typically used to describe temperature effects on nitrification. Thus, temperature effects have to be considered when nitrogen removal is targeted and the biofilter might be exposed to cold temperatures.

  • 24. Blecken, Godecke-Tobias
    et al.
    Zinger, Yaron
    Monash University, Melbourne, VIC.
    Deletic, Ana
    Monash University, Melbourne, VIC.
    Fletcher, Tim
    Monash University, Melbourne, VIC.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Heavy metal removal by stormwater biofilters: can it withstand alternative drying and wetting conditions?2008In: Conference Proceedings : 11th International Conference on Urban Drainage: Edinburgh International Conference Centre, Scotland : 11 ICUD: 31st August - 5th September 2008, Munich: Oldenbourg Industrieverlag , 2008Conference paper (Refereed)
    Abstract [en]

    Urban stormwater contains substantial loads of Cu, Pb and Zn, which are considered as key stormwater contaminants. Stormwater biofiltration is a promising option to treat these contaminants. Biofilters are exposed to an alternate cycle of drying and wetting, and the influence of this on pollutant removal performance is as-yet unknown. To investigate the effect of drying and subsequent rewetting on the retention of heavy metals by stormwater biofilters, a laboratory study has been conducted using three groups of biofilter columns, which were dosed with semi-synthetic stormwater according to three different drying and wetting regimes. Some biofilters were fitted with a submerged zone combined with a carbon source, at the bottom of the filter. Overall, the biofilters were very effective in heavy metal removal, provided that they received regular stormwater input. However, after drying extending to three or four weeks, removal of heavy metals decreased significantly. A statistically significant correlation between antecedent dry days and metal removal was shown. Furthermore, a clear effect of the submerged zone was found: after extended dry periods, biofilters with this feature performed significantly better than those without it. In particular, the removal of Cu was clearly increased both during wet and dry periods; for Pb the negative effect of drying was completely eliminated by introducing a submerged zone.

  • 25. Blecken, Godecke-Tobias
    et al.
    Zinger, Yaron
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Deletic, Ana
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Fletcher, Tim
    Facility for Advancing Water Biofiltration, Department of Civil Engineering, Monash University.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Influence of intermittent wetting and drying conditions on heavy metal removal by stormwater biofilters2009In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 43, no 18, p. 4590-4598Article in journal (Refereed)
    Abstract [en]

    Biofiltration is a technology to treat urban stormwater runoff which conveys pollutants, including heavy metals. However, the variability of metals removal performance in biofiltration systems is as yet unknown.A laboratory study has been conducted with vegetated biofilter mesocosms, partly fitted with a submerged zone at the bottom of the filter combined with a carbon source. The biofilters were dosed with stormwater according to three different dry/wet schemes, to investigate the effect of intermittent wetting and drying conditions on metal removal.Provided that the biofilters received regular stormwater input, metal removal exceeded 95%. The highest metal accumulation occurs in the top layer of the filter media.However, after antecedent drying before a storm event exceeding three to four weeks the filters performed significantly worse, although metal removal still remained relatively high. Introducing a submerged zone into the filter improved the performance significantly after extended dry periods. In particular, copper removal in filters equipped with a submerged zone was increased by around 12% (α = 0.05) both during wet and dry periods and for lead the negative effect of drying could completely be eliminated, with consistently low outflow concentrations even after long drying periods.

  • 26. Blecken, Godecke-Tobias
    et al.
    Zinger, Yaron
    Monash University, Melbourne, VIC.
    Muthanna, Tone M.
    Norwegian Institute for Water Research (NIVA), Trondheim.
    Deletic, Ana
    Monash University, Melbourne, VIC.
    Fletcher, Tim D.
    Monash University, Melbourne, VIC.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    The influence of temperature on nutrient treatment efficiency in stormwater biofilter systems2007In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 56, no 10, p. 83-91Article in journal (Refereed)
    Abstract [en]

    Nutrients can cause eutrophication of natural water bodies. Thus, urban stormwater which is an important nutrient source in urbanised areas has to be treated in order to reduce its nutrient loads. Biofilters which use soil filter media, biofilms and plants, are a good treatment option for nutrients. This paper presents the results of a biofilter column study in cold temperatures (+2 °C, +8 °C, control at +20 °C) which may cause special problems regarding biofilter performance. It was shown that particle-bound pollutants as TSS and a high fraction of phosphorus were reduced well without being negatively influenced by cold temperatures. Nitrogen, however, was not reduced; especially NOx was produced in the columns. This behaviour can be explained with both insufficient denitrification and high leaching from the columns

  • 27.
    Galfi, Helen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Haapala, Jenny
    Vatten Östersund.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Länsstyrelsen i Norrbotten.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Indicator bacteria variation in separate sewer systems in Östersund, Sweden: Preliminary results2013Conference paper (Refereed)
    Abstract [en]

    Faecal bacteria are a major pollution threat of water bodies designated for multipurpose use including drinking water sources or recreational purposes. Even though stormwater discharges may contribute significantly to microbiological pollution, they have not been fully investigated in the European context. We have studied the presence of indicator bacteria and total suspended solids (TSS) in stormwater discharged from four urban catchments, with areas between 5 and 40 ha, in Östersund, Sweden. The aim was to determine local variation of standard bacteria strains and TSS in Swedish urban catchments with specific land uses. Further, intra event variations were investigated. During dry weather, indicator bacteria concentrations in sewers conveying baseflow did not exceed 100 CFU/100 mL. During storm runoff, total coliform and int. enterococci concentrations increased 102 to 103 times, compared to those in baseflow. Compared to these two parameters, considerably lower concentrations were observed for E. coli and C. perfringens. Bacteria concentrations differed significantly among the sampling sites and partly, a first flush phenomenon was observed. Partly, significant correlations between TSS and indicator bacteria were observed. These were catchment specific and need a more detailed assessment. Further research will focus on seasonal variations and influential factors.

  • 28.
    Galfi, Helen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Haapala, Jenny
    Vatten Östersund, Water Engineering, Water Department Östersund, Östersund Municipality.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Westerlund, Camilla
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Inter-Event and Intra-Event Variations of Indicator Bacteria Concentrations in the Storm Sewer System of the City of Östersund, Sweden2016In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 142, no 7, article id 6016003Article in journal (Refereed)
    Abstract [en]

    An episode of microbiological contamination of the drinking water supply of the City of Östersund, Sweden (63°10′45″N; 14°38′09″E) prompted a study of fecal pollution in four storm drainage catchments discharging in the vicinity of the water treatment plant intake, with the overall aim of determining the presence and variation of standard fecal indicator bacteria strains and total suspended solids (TSS) in stormwater from urban catchments with specific land uses and sizes varying from 5 to 40 ha. Four bacteria strains used as indicators of fecal pollution in Sweden were studied: total coliforms, enterococci, Escherichia coli (E. coli) and Clostridium perfringens (C. perfringens). In dry weather, indicator bacteria concentrations in storm sewers conveying baseflow did not exceed 100  colony forming units (CFU)/100  mL 100  colony forming units (CFU)/100  mL, but during wet weather, total coliform and enterococci concentrations increased 10 2 102 to 10 3 103 times, compared to those in baseflow, and considerably less in the case of E. coli and C. perfringens. Bacteria concentrations differed significantly among the sampling sites and in the majority of events observed in the four catchments; higher bacteria concentrations were observed during the early phases of runoff. Only in one catchment, positive correlations were observed between TSS and total coliforms, E. coli, and enterococci, suggesting similar sources; in the remaining catchments, no such correlations were observed. The collected indicator bacteria data represent a useful addition to the available data on indicator bacteria in stormwater in cold-climate regions.

  • 29.
    Galfi, Helen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Influence of sampling methods on the measurements of urban stormwater quality constituents: Preliminary results2013Conference paper (Refereed)
    Abstract [en]

    The choice between automatic and manual sampling of urban stormwater quality has been addressed in the past as an issue of economic efficiency, field safety, and practicality. Nevertheless, there is experimental evidence that both types of sampling may yield statistically different stormwater quality data. While the past attention focused on differences in sampled solids, a new issue was addressed in this study, the potential impacts of sampling methods on concentrations of indicator bacteria. Towards this end, four indicator bacteria (coliforms, E. coli, enterococci and C. perfringens) were sampled in storm sewers of two urban catchments in Östersund, Sweden, using both automatic samplers and manual sampling. Such data were further supplemented by measurements of total suspended solids (TSS) and turbidity, recognizing that bacteria are mostly transported in the attachment to solids. Preliminary results indicate that there may be large differences between indicator bacteria in automatic and manual samples, with E. coli measurements yielding the least differences, and turbidity readings were correlated well with all the indicator bacteria and particularly E. coli. These findings will be used in the continuation of this study for refining the existing experimental design and developing practical guidance for surveys of municipal storm sewers for faecal pollution.

  • 30.
    Galfi, Helen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nordqvist, Kerstin
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Sundelin, Monica
    Hjortens Lab, Östersund.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, Jiri
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Comparison of indicator bacteria concentrations obtained by automated and manual sampling of urban stormwater runoff2014In: Water, Air and Soil Pollution, ISSN 0049-6979, E-ISSN 1573-2932, Vol. 225, no 9, article id 2065Article in journal (Refereed)
    Abstract [en]

    A comparative study of indicator bacteria concentrations obtained by laboratory analysis of grab samples of storm water, which were collected manually or by automatic samplers, was carried out in two urban catchments. Samples were analyzed for four types of indicator bacteria, total coliforms, Escherichia coli (E. coli), enterococci, and Clostridium perfringens and further documented by measurements of total suspended solids (TSS) and turbidity. Analysis of complete data sets (N=198) indicated no statistically significant differences in the geometric means of all the constituent samples collected automatically or manually, but there were some small differences between the results produced by the two sampling methods applied. Total coliform concentrations were positively biased in samples collected by automatic samplers, but for the three remaining indicator bacteria (E. coli, enterococci, and C. perfringens), the opposite was true. Risk of sample cross-contamination in automatic samplers was assessed in the laboratory by sampling consecutively synthetic storm water with high and low concentrations of E. coli and enterococci. The first low-concentration samples preceded by high-concentration samples were cross-contaminated and the measured concentrations were positively biased. This cross-contamination was explained by storm-water residue in the sampling line. Such a residue remained in place even after line purging by compressed air, and its mass depended on the sampling line length (tested up to 5 m), as verified by measurements in the laboratory. The study findings should be helpful for improving field protocols for indicator bacteria sampling.

  • 31.
    Goldkuhl, Lena
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Urban water research in an urban living lab setting: How does it work?2017In: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017Conference paper (Refereed)
  • 32.
    Karlsson, Kristin
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Environmental Risk Assessment of Sediments Deposited in Stormwater Treatment Facilities: Trace Metal Fractionation and Its Implication for Sediment Management2016In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 142, no 11, article id 4016057Article in journal (Refereed)
    Abstract [en]

    To gather further data about metal mobility in accumulated sediments in stormwater treatment facilities, metal mobility in sediments from sedimentation tanks, gully pot sediment traps, and sedimentation ponds was investigated using the sequential extraction procedure. This method allows distinguishing the metal speciation between ion-exchangeable, carbonate-associated, reducible, organic matter/sulfide-associated, and residual fractions. The metal fractionation reveals that, for all treatment facilities, the majority of Cd, Cu, Pb, and Zn and a significant amount of Ni were in potentially mobile forms. Cd, Pb, and Zn are, to a large extent, associated with Fe-Mn oxides while Cu is commonly present as Cu–organic matter complexes. The metals in these potentially mobile fractions may represent a potential environmental hazard, e.g., due to release during maintenance (sediment removal) when the chemical phase distribution might change.

  • 33.
    Leonhardt, Günther
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bacchin, Taneha K
    Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology.
    Mair, Michael
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Zischg, Jonathan
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Ljung, Stina
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Rogers, Briony
    School of Social Sciences, Monash Water for Liveability Centre, Monash University.
    Goldkuhl, Lena
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Gustafsson, Anna-Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Sitzenfrei, Robert
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Ashley, Richard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Rauch, Wolfgang
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Timmeren, Arjan van
    Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Relocating a city, challenges and opportunities for the transition of water infrastructure in Kiruna2015In: Urban Drainage Modelling 2015: Proceedings of the 10th International Conference of Urban Drainage Modelling, Mont-Sainte-Anne, Québec, Canada 20-23 Swptember 2015 / [ed] Thomas Maere; Sovanna Tik; Sophie Duchense; Peter A. Vanrolleghem, 2015, p. 77-84Conference paper (Refereed)
  • 34.
    Lönnqvist, Joel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Plant cover and species compositions on subarctic green roofs2017In: 14th IWA/IAHR International Conference on Urban Drainage in Prague, Czech Republic 10-15 September 2017, 2017Conference paper (Other academic)
    Abstract [en]

    Thisstudy looked at the plant cover and species composition of green roofs in a subarctic climate. The study’s aim was to evaluate the cover of plants and moss on green roofs in northern Sweden. Data was gathered from a field survey in summer 2016 andevaluatedroof sections located on buildings in three different towns located on a latitudinal gradient.Apart from plant cover substrate depth, slope andexposure was recorded. The results showed that the average vascular plant cover was low in the two northern locations (32% and 27%) while in the southernmost location it was high (>85%).

  • 35.
    Lönnqvist, Joel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Evaluating the plant cover of northern Sweden's green roofs2017In: Proceedings of EtW2017, 2017Conference paper (Other academic)
  • 36.
    Mattsson, Jonathan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Fat, Oil, and Grease Accumulation in Sewer Systems: Comprehensive Survey of Experiences of Scandinavian Municipalities2014In: Journal of environmental engineering, ISSN 0733-9372, E-ISSN 1943-7870, Vol. 140, no 3, article id 4014003Article in journal (Refereed)
    Abstract [en]

    Problems with fat, oil, and grease (FOG) in sewer systems have received relatively little attention, although in the longer term this might imply (inter alia) blockages and sanitary overflows. Therefore, the experiences of Swedish and Norwegian executive water engineers concerning FOG-related issues were assessed using a comprehensive questionnaire that was distributed to all Swedish and Norwegian municipalities (with a response rate of 35% and 25% in Sweden and Norway, respectively). Blockages caused by FOG in sewers and pumping stations were the most prevalent reported problem, followed by increased demand for line flushing. The water engineers singled out city centers as the areas whose sewers had the most severe problems with FOG buildups. Most municipalities mandated the use of grease interceptors (GIs) by businesses, but the maintenance and functional status of these devices were reported to be inadequate. Commonly, water engineers had faith in the functioning of the GI despite the lack of stringent inspections. Where FOG collection systems had been implemented, they generally targeted businesses and other enterprises rather than private households. Because problems caused by FOG buildups are likely to become more common in the future, it is important that prevention strategies characterize management to a higher degree than ones based on removal.

  • 37.
    Merriman, Laura S.
    et al.
    Biological & Agricultural Engineering, North Carolina State University.
    Moore, T.L.C.
    Biological & Agricultural Engineering, Kansas State University.
    Wang, J.W.
    Centre for Urban Greenery and Ecology, National Parks Board, 1E Cluny Road, 259569, Singapore.
    Osmond, D.L.
    Soil Science, North Carolina State University.
    Al-Rubaei, Ahmed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Smolek, A.P.
    Biological & Agricultural Engineering, North Carolina State University.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hunt, William F.
    Biological & Agricultural Engineering, North Carolina State University.
    Evaluation of factors affecting soil carbon sequestration services of stormwater wet retention ponds in varying climate zones.2017In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 583, p. 133-141Article in journal (Refereed)
    Abstract [en]

    The carbon sequestration services of stormwater wet retention ponds were investigated in four different climates: U.S., Northern Sweden, Southern Sweden, and Singapore, representing a range of annual mean temperatures, growing season lengths and rainfall depths: geographic factors that were not statistically compared, but have great effect on carbon (C) accumulation. A chronosequence was used to estimate C accumulations rates; C accumulation and decomposition rates were not directly measured. C accumulated significantly over time in vegetated shallow water areas (0–30 cm) in the USA (78.4 g C m− 2 yr− 1), in vegetated temporary inundation zones in Sweden (75.8 g C m− 2 yr− 1), and in all ponds in Singapore (135 g C m− 2 yr− 1). Vegetative production appeared to exert a stronger influence on relative C accumulation rates than decomposition. Comparing among the four climatic zones, the effects of increasing rainfall and growing season lengths (vegetative production) outweighed the effects of higher temperature on decomposition rates. Littoral vegetation was a significant source to the soil C pool relative to C sources draining from watersheds. Establishment of vegetation in the shallow water zones of retention ponds is vital to providing a C source to the soil. Thus, the width of littoral shelves containing this vegetation along the perimeter may be increased if C sequestration is a design goal. This assessment establishes that stormwater wet retention ponds can sequester C across different climate zones with generally annual rainfall and lengths of growing season being important general factors for C accumulation.

  • 38.
    Muthanna, Tone Merete
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Thorolfsson, Sveinn T.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Snowmelt pollutant removal in bioretention areas2007In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 41, no 18, p. 4061-4072Article in journal (Refereed)
    Abstract [en]

    Snow accumulating in urban areas and alongside roads can accumulate high pollutant loads and the subsequent snowmelt can produce high pollutant loads in receiving waters. This paper examines the treatment of roadside snowmelt in bioretention with respect to pollutant removal, pollutant pathways, and major sinks. Bioretention was used to treat snowmelt from three types of urban roads in Trondheim, Norway: residential, medium, and roads with high-density traffic. Metal retention in bioretention boxes had a mass reduction in zinc, copper, lead, and cadmium in the range of 89-99%, and a decrease in outflow concentrations in the range 81-99%. Cadmium was only measured in the water samples, while the other three metals were traced through the system to identify the main sinks. The top mulch layer was the largest sink for the retained metals, with up to 74% of the zinc retained in this mulch layer. The plant metal uptakes were only 2-8% of the total metal retention; however, the plants still play an important role with respect to root zone development and regeneration, which fosters infiltration and reduces the outflow load. Dissolved pollutants in snowmelt tend to be removed with the first flush of meltwater, creating an enrichment ratio with respect to the average pollutant concentrations in the snow. The effect of this enrichment ratio was examined through the bioretention system, and found to be less predominant than that typically reported for untreated snowmelt. The enrichment factors were in the range of 0.65-1.51 for the studied metals.

  • 39.
    Rentz, Ralf
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Malmgren, Charlotte
    Luleå University of Technology, Department of Business Administration, Technology and Social Sciences, Business Administration and Industrial Engineering.
    Öhlander, Björn
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Stormwater impact on urban water bodies: seasonal variations in sediment metal concentrations in a cold climate - preliminary results2011Conference paper (Other academic)
    Abstract [en]

    In this paper, preliminary results of a study investigating the impact of stormwater discharges on the bottom sediment of stormwater recipients in Luleå, northern Sweden are presented. The aim was to evaluate sediment metal concentrations taken in front of stormwater sewer discharge points from two ditches/recipients, their seasonal variation and the influence of geomorphology and vegetation on the metal distribution. Compared with northern Sweden background values, the Cd, Cu, Pb and Zn concentrations in the sediment samples were elevated. However, besides stormwater discharges, local sulphide soils in the catchment areas can affect the metal concentrations. Partly, seasonal variations in the metal concentrations were noticed; higher metal concentrations were observed in spring associated with a high LOI content and large fractions of fine grain size particles (<0.125 mm). Low/no runoff in winter and metal accumulation in snow followed by continuous snow melt runoff transports mostly fine grain sizes and therewith associated metals, which then settle and accumulate in the ditches/recipients. Dense reed vegetation can retain coarse grain sizes and supplies the sediment with decomposing organic material. Decomposition processes affect the redox conditions in the sediment through oxygen consumption. In the reduced sediment metals can be trapped in combination with sulphide formation.

  • 40.
    Stott, Rebecca
    et al.
    Aquatic Pollution Group, National Institute of Water and Atmospheric Research, Hamilton.
    Tondera, Katharina
    Stormwater Research Group, University of the Sunshine Coast, Maroochydore.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Schreiber, Christiane
    GeoHealth Centre, Institute for Hygiene & Public Health, University Hospital, University of Bonn.
    Microbial Loads and Removal Efficiency Under Varying Flows2018In: Ecotechnologies for the Treatment of Variable Stormwater and Wastewater Flows / [ed] Katharina Tondera, Godecke-Tobias Blecken, Florent Chazarenc, Chris C. Tanner, Cham: Springer, 2018, p. 57-74Chapter in book (Refereed)
    Abstract [en]

    A variety of ecotechnologies have shown promising yet variable results in reducing faecal microbial contaminants under challenging operational conditions. But relatively limited work has been conducted to investigate and understand faecal microbe removal in these systems under highly fluctuating hydraulic and contaminant loading. In most instances, ecotechnology-based systems such as sedimentation ponds, constructed wetlands and bioretention filters have proved effective for treating episodic discharges and demonstrated performance resilience removing faecal microbial contaminants with modest to good efficiency particularly where inflow concentrations are high. However, microbial removal may depend greatly on the type of microorganism, treatment system design and operational factors. Design characteristics such as type of filter material and depth, presence of a submerged zone, type of vegetation and operational conditions such as inflow concentration, and antecedent dry periods in combination with temperature changes can all affect the removal of faecal microbes. Factors influencing survival, fate and behaviour of retained faecal microbes are still poorly understood. These knowledge gaps need addressing in order to fully evaluate microbial removal from fluctuating contaminated flows and more accurately interpret faecal indicator bacteria-based water quality and potential health risks associated with discharge from these ecotechnology-based systems

  • 41.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    The influence of temperature and salt on metal and sediment removal in stormwater biofilters2014In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 69, no 11, p. 2295-2304Article in journal (Refereed)
    Abstract [en]

    Stormwater biofilters are used to treat stormwater runoff. In countries with cold winter climates, biofilters are subject to low temperatures which, in some cases, are combined with potentially high salt concentrations from road de-icing, potentially affecting the biofilter’s performance. Since stormwater biofilters have been developed without consideration of their critical winter use, a laboratory study was carried out to evaluate the performance of stormwater biofilters subjected to low and high temperatures, with and without salt. Both factors and their interaction had a significant effect on outflow concentrations and removal percentages. Salt had a negative impact on outflow concentrations, causing lower removal percentages for (especially dissolved) metals, this impact being most pronounced for Cu and Pb. The unrealistic combination of salt with high temperature seemed to further amplify the negative impacts of salt despite the fact that temperature alone did not cause significant differences in outflow concentrations and removal percentages. Still, biofilters showed the ability to treat stormwater efficiently under the simulated winter conditions; outflow concentrations for total metals as a minimum met the class 4 threshold value defined in the Swedish freshwater quality guidelines, while inflow concentrations clearly exceeded the threshold value for class 5. The relatively coarse filter material (which is recommended to facilitate infiltration during winter) did not seem to exacerbate biofilter performance.

  • 42.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Metal uptake in three different plant species used for cold climate biofilter systems2014Conference paper (Refereed)
    Abstract [en]

    Stormwater biofilters have been developed without consideration of their cold climate design and performance. Vegetation has been shown to play an important role in biofilter effectiveness. Due to the effect of winter conditions on plants (no/reduced growth, high salinity from road salt), winter-related factors affecting biofilter vegetation, and especially the selection of vegetation for cold climate biofilter systems, need further investigation. The impacts of temperature, salt and the presence of a submerged zone on Cd, Cu, Pb and Zn uptake in three native wet/drought tolerant plant types, Juncus conglomeratus, Phalaris arundinacea and Carex panacea, were thus examined in 24 biofilter mesocosms under controlled laboratory conditions. The shoots of all three plant species accumulated higher metal concentrations than the roots. Generally, a higher metal uptake was observed under cold conditions. No significant difference in metal uptake was found between different biofilter combinations, indicating that these three plant species were not particularly affected by different temperatures and/or the presence/absence of salt and a submerged zone. The results of this study indicate the potential to use the investigated plant species for targeted cold climate biofilter design.

  • 43.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Do salt and low temperature impair metal treatment in stormwater bioretention cells with or without a submerged zone?2017In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 579, p. 1588-1599Article in journal (Refereed)
    Abstract [en]

    Although seasonal temperature changes and (road) salt in winter and/or coastal stormwater runoff might interfere with the metal treatment performance of stormwater bioretention cells, no previous study has evaluated the effect of these factors and their interactions under controlled conditions. In this 18 week long study 24 well established pilot-scale bioretention columns were employed to evaluate the individual and combined effect(s) of low/high temperature, salt and presence of a submerged zone with an embedded carbon source on metal removal using a three factor, two-level full factorial experimental design. In most instances, the three factors significantly influenced the metal outflow concentrations and thus the treatment performance; the effect of temperature depended on the metal in question, salt had an overall negative effect and the submerged zone with carbon source had an overall positive effect. Despite these statistically significant effects, the discharge water quality was generally markedly improved. However, leaching of dissolved Cu and Pb did occur, mainly from bioretention cells dosed with salt-containing stormwater. The highest concentrations of metals were captured in the top layer of the filter material and were not significantly affected by the three factors studied. Overall, the results confirmed that bioretention provides a functioning stormwater treatment option in areas experiencing winter conditions (road salt, low temperatures) or coastal regions (salt-laden stormwater). However, validation of these results in the field is recommended, especially focusing on dissolved metal removal, which may be critically affected under certain conditions.

  • 44.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Hedström, Annelie
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Reduction of Escherichia coliEnterococcus faecalisand Pseudomonas aeruginosa in stormwater bioretention: Effect of drying, temperature and submerged zone2019In: Journal of Hydrology X, ISSN 2589-9155, Vol. 3, article id 100025Article in journal (Refereed)
    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.

  • 45.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Vollertsen, Jes
    Department of Civil Engineering, Aalborg University.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Nielsen, Asbjørn Haaning
    Department of Civil Engineering, Aalborg University.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bioaccumulation of heavy metals in two wet retention ponds2016In: Urban Water Journal, ISSN 1573-062X, Vol. 13, no 7, p. 697-709Article in journal (Refereed)
    Abstract [en]

    Metal accumulation in stormwater ponds may contaminate the inhabiting fauna, thus jeopardizing their ecosystem services function. We evaluated bioaccumulation of metals in natural fauna and caged mussel indicator organisms in two wet retention ponds. Mussel cages were distributed throughout the ponds to detect bioaccumulation gradients and obtain a time-integrated measure of metal bioavailability. We further investigated if sediment metal concentrations correlate with those in the fauna and mussels. Metal concentrations in the fauna tended to be higher in the ponds than in a reference lake, but statistical significance was only shown for Cu. Positive correlations were found for some metals in fauna and sediment. Sediment metal concentrations in one pond decreased from inlet to outlet while no gradients were observed in the mussels in either pond. These findings indicate that metal accumulation in the examined ponds currently does not pose a threat to their habitat function.

  • 46.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Vollertsen, Jes
    Section of Water and Soil, Department of Civil Engineering, Aalborg University.
    Nielsen, Asbjørn Haaning
    Section of Water and Soil, Department of Civil Engineering, Aalborg University.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    A comparison of freshwater mussels and passive samplers as indicators of heavy metal pollution in aquatic systems2013Conference paper (Refereed)
    Abstract [en]

    The utility of passive sampling as a tool for determining the ecological state of wet retention ponds was investigated as an alternative to the analysis of living organisms. The accumulation of heavy metals over time in mussels and passive samplers exposed to artificial stormwater was examined under controlled conditions in order to determine whether either system was capable of functioning as a reliable source of data on aquatic pollution. The laboratory results indicated that mussels are useful in this context. However, passive samplers will require further development to be useful since there was no strong correlation between the heavy metal concentrations observed in the mussels and those in the passive samplers.

  • 47.
    Søberg, Laila
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Winston, Ryan
    Departments of Food, Agricultural, and Biological Engineering and Civil, Environmental, and Geodetic Engineering, Ohio State University, 590 Woody Hayes Drive, Columbus, OH, United States of America.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Dissolved metal adsorption capacities and fractionation in filter materials for use in stormwater bioretention facilities2019In: Water Research X, ISSN 2589-9147, Vol. 4, article id 100032Article in journal (Refereed)
    Abstract [en]

    The dissolved metal adsorption and association was determined for ten different filter materials recommended and/or implemented in bioretention facilities. Batch adsorption and batch kinetic experiments were performed at lab-scale using both single and multi-metal solutions. Metal strengths and association were determined by sequential extraction analysis. All materials adsorbed metals and 90% of adsorption occurred within 1 h. However, as metal solutions became more complex, adsorption behavior changed. Generally, filter materials classified as sand with a naturally high pH, relatively low organic matter (OM) content and large specific surface area seem to be good choices for removing dissolved metals. Additionally, a chalk additive might improve metal adsorption whereas biochar did not significantly improve metal retention and may be an unwanted (due to degradation over time) extra source of OM. Regardless of filter material, metals primarily adsorbed to the exchangeable form which indicates that metal adsorption might not be permanent, but rather substantially reversible in some cases. More research is needed to assess whether dissolved metals adsorbed in filter materials of bioretention systems pose a delayed threat instead of an immediate threat. Finally, the authors strongly recommend filter materials intended for stormwater bioretention facilities to be tested prior to implementation.

  • 48.
    Tondera, Katharina
    et al.
    Stormwater Research Group, University of the Sunshine Coast, Maroochydore.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Chazarenc, Florent
    Department of Energy Systems and Environment, Institut Mines Telecom Atlantique, Nantes cedex 3.
    Lucke, Terry
    Stormwater Research Group, University of the Sunshine Coast, Maroochydore .
    Tanner, Chris C.
    National Institute of Water and Atmospheric Research, Hamilton.
    Treatment Techniques for Variable Flows2018In: Ecotechnologies for the Treatment of Variable Stormwater and Wastewater Flows / [ed] Katharina Tondera, Godecke-Tobias Blecken, Florent Chazarenc, Chris C. Tanner, Cham: Springer, 2018, p. 7-30Chapter in book (Refereed)
    Abstract [en]

    A wide range of ecotechnologies has been applied to treatment of variable stormwater and wastewater flows. Stormwater ponds and basins were already introduced as common ‘end-of-the-pipe’ treatment solutions in the 1960s, almost parallel to the first attempts to develop structured wastewater treatment with the help of plants, inspired by natural wetlands. Constructed wetlands specifically designed for the treatment of variable flows emerged in the 1990s and were joined by a growing group of vegetated filter systems, named bioretention filters, raingardens or retention soil filters, all following the principle of gravity-driven wastewater filtration. This chapter provides a general overview of these treatment facilities, including swales and buffer strips. Although the latter ones are gravity-driven filtration systems, they are commonly used for the treatment of road runoff and are highly adapted to fit into their landscape structure, they are described in a separate section. Each section includes references to detailed design and operation guidelines.

  • 49.
    Tondera, Katharina
    et al.
    Institute of Environmental Engineering, RWTH Aachen University, Aachen.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Tournebize, Julien
    Hydrosystems and Bioprocessus Research Unit, Irstea—National Research Institute of Science and Technology for Environment and Agriculture, Antony.
    Mander, Ülo
    Department of Geography, University of Tartu.
    Tanner, Chris C.
    National Institute of Water and Atmospheric Research, Hamilton.
    Nutrient Removal from Variable Stormwater Flows2018In: Ecotechnologies for the Treatment of Variable Stormwater and Wastewater Flows / [ed] Katharina Tondera, Godecke-Tobias Blecken, Florent Chazarenc, Chris C. Tanner, Cham: Springer, 2018, p. 31-55Chapter in book (Refereed)
    Abstract [en]

    When nutrient loads are discharged into surface waters with variable stormwater and wastewater flows, surface water pollution is impaired. Nutrients can lead to oxygen depletion and eutrophication of surface waters, including excessive plant and algae growth. Popular examples of structures harmed by excessive nutrient inflow are the Baltic Sea or the Great Barrier Reef in Australia. Hence, removing nutrients, especially nitrogen and phosphorus compounds, is a major target when variable flows should be treated. This chapter gives an overview of the available removal mechanisms and the potential efficiencies of different treatment facilities. While particle-bound nutrients can be removed via sedimentation processes, dissolved nitrogen and phosphorus compounds cannot as they differ in their biochemical degradation: the adsorption capacity for nitrogen compounds is often renewable, whereas the uptake of phosphorus compounds is limited over time. Hence, treatment facilities need to be able to address the different requirements.

  • 50.
    Tondera, Katharina
    et al.
    Institute of Environmental Engineering, RWTH Aachen University, Aachen.
    Blecken, Godecke-Tobias
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Tournebize, Julien
    Hydrosystems and Bioprocessus Research Unit, Irstea—National Research Institute of Science and Technology for Environment and Agriculture, Antony.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Österlund, Helene
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Andersson-Wikström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Tanner, Chris C.
    National Institute of Water and Atmospheric Research, Hamilton.
    Emerging Contaminants: Occurrence, Treatment Efficiency and Accumulation Under Varying Flows2018In: Ecotechnologies for the Treatment of Variable Stormwater and Wastewater Flows / [ed] Katharina Tondera, Godecke-Tobias Blecken, Florent Chazarenc, Chris C. Tanner, Cham: Springer, 2018, p. 93-109Chapter in book (Refereed)
    Abstract [en]

    Emerging contaminants became a major topic in water treatment when laboratory detection methods for concentrations at a nanogram-scale improved approximately two decades ago. Research on using ecotechnologies to remove emerging contaminants in variable stormwater and wastewater flows has been conducted for more than a decade, but so far, not all removal mechanisms are well understood and only few setups have been investigated. This chapter summarises the current knowledge, focussing on pesticides and emerging contaminants listed on the watch list of the European Union. However, large-scale investigations are still rare and further research will have to be conducted in this field to enable practitioners to provide recommendations for design and maintenance of treatment facilities in the field of ecotechnologies.

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