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  • 1. 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

  • 2.
    Borris, Matthias
    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.
    Gustafsson, Anna-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.
    Simulating future trends in urban stormwater quality for changing climate, urban land use and environmental controls2013In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 68, no 9, p. 2082-2089Article in journal (Refereed)
    Abstract [en]

    The effects of climatic changes, progressing urbanization and improved environmental controls on the simulated urban stormwater quality in a northern Sweden community were studied. Future scenarios accounting for those changes were developed and their effects simulated with the Storm Water Management Model (SWMM). It was observed that the simulated stormwater quality was highly sensitive to the scenarios, mimicking progressing urbanization with varying catchment imperviousness and area. Thus, land use change was identified as one of the most influential factors and in some scenarios, urban growth caused changes in runoff quantity and quality exceeding those caused by a changing climate. Adaptation measures, including the reduction of directly connected impervious surfaces (DCIS) through the integration of more green spaces into the urban landscape, or disconnection of DCIS were effective in reducing runoff volume and pollutant loads. Furthermore, pollutant source control measures, including material substitution, were effective in reducing pollutant loads and significantly improving stormwater quality

  • 3.
    Borris, Matthias
    et al.
    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.
    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.
    An exploratory study of the effects of stormwater pipeline materials on transported stormwater quality2017In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 76, no 2, p. 247-255Article in journal (Refereed)
    Abstract [en]

    Implications of three sewer pipe materials (concrete, galvanized corrugated steel, and polyvinyl chloride (PVC)) for stormwater quality were explored in laboratory experiments, in which three types of stormwater, SW1-SW3, were circulated in 0.5 m long sewer pipe sections. SW1 and SW2 represented synthetic rainwater, without and with fine street sediment added (CTSS = 150 mg/L), respectively, and SW3 was actual stormwater with the same sediment addition as SW2. Following 20-min runs, with an equivalent distance of 500 m travelled by water particles, a number of statistically significant changes in the stormwater chemistry were observed: (i) pH of all the simulated stormwaters increased in the concrete pipe (from 7.0-7.3 to 8.1-9.3), (ii) turbidity decreased in two stormwaters with sediments (SW2 and SW3) in concrete and galvanized corrugated steel pipes (by 50 and 85%, respectively), (iii) the type of stormwater affected the observed copper (Cu) concentrations, with Cudiss concentrations as high as 25.3 μg/L noted in SW3 passing through the PVC pipe, and (iv) zinc (Zn) concentrations sharply increased (Zntot = 759-1,406 μg/L, Zndiss = 670-1,400 μg/L) due to Zn elution from the galvanized steel pipe by all three stormwaters. Such levels exceeded the applicable environmental guidelines.

  • 4. Bäckström, Magnus
    Grassed swales for stormwater pollution control during rain and snowmelt2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 123-134Article in journal (Refereed)
    Abstract [en]

    The retention of suspended solids, particles and heavy metals in different grassed swales during rain events and snowmelt is discussed. The experimental results derived from investigations performed in existing grassed swales in the Luleae. region, Northern Sweden. During high pollutant loading rates, grassed swales retain significant amounts of pollutants, mainly due to sedimentation of particulate matter. Low to moderate removal efficiencies could be expected for heavy metals, especially metals in solution (i.e. the dissolved phase). When grassed swales receive urban runoff with low pollutant concentrations, they may release rather than retain pollutants. Swales are important snow deposit areas in the city and particle bound pollutants do to a large extent remain in the swale after snowmelt. However, dissolved pollutants (i.e. dissolved heavy metals) are likely to escape the swale with the melt water. Grassed swales may be regarded as facilities that even out the peaks in pollutant loads without being capable of producing consistent high removal rates. This suggests that swales should be considered as primary treatment devices. Possible design parameters for grassed swales are mean hydraulic detention time, surface loading rate or specific swale area.

  • 5. Bäckström, Magnus
    Sediment transport in grassed swales during simulated runoff events2002In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 45, no 7, p. 41-49Article in journal (Refereed)
    Abstract [en]

    Particle trapping in nine different grassed swales was measured successfully with a standardised runoff event simulation procedure. The percentage of total suspended solids removed ranged from 79 to 98%. It was found that sedimentation processes, rather than grass filtration governed the overall particle trapping efficiency. The highest particle trapping efficiency was observed in the field swales with dense, fully developed turf. A high infiltration rate was beneficial for the particle trapping and an increased swale length made it possible for smaller particles to be captured. A densely vegetated, ten metre long swale, receiving a stormwater flow of 1.0 litres per second, may capture a majority of the waterborne particles with settling velocities larger than 0.1 metres per hour. A simple model of particle trapping efficiency in grassed swales was developed and tested. It was found that mean swale residence time could be used as a design parameter for particle removal in grassed swales. The suggested exponential relationship between mean swale residence time and particle settling velocity associated with a certain trapping efficiency is so far only valid for a limited range of swale designs and residence times.

  • 6. Bäckström, Magnus
    et al.
    Malmqvist, Per-Arne
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Stormwater management in a catchbasin perspective - best practices or sustainable strategies?2002In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 46, no 6-7, p. 159-166Article in journal (Refereed)
    Abstract [en]

    A strategy for sustainable stormwater management is needed. This study has focused on the relative importance of stormwater as a pollutant source in a catchbasin, if Best Management Practices (BMPs) result in pollutant removal or pollutant redistribution, and methods for screening of stormwater strategies. Stormwater is most likely an important pathway for pollutants in a catchbasin perspective. True pollutant removal can only be achieved if the pollutant sources are eliminated. Until that is reached, we should have the best possible control of the pollutant fluxes in the watershed. This study indicates that the search for a sustainable stormwater strategy could be easier to handle if different "screens" could be used. The Swedish environmental objectives, which try to encapsulate all aspects of sustainability, may be used as a foundation for a "sustainability screen". By using this screen, the "unsustainable" features of different stormwater strategies could be pointed out. A "standards and legislation screen" will be based on the EU Water Framework Directive. As this study has shown, it is doubtful whether the conventional BMPs, such as stormwater ponds and infiltration facilities, produce a sufficient pollutant control.

  • 7. Hanaeus, Jörgen
    et al.
    Hellström, Daniel
    Johansson, Erica
    Luleå tekniska universitet.
    A study of a urine separation system in an ecological village in northern Sweden1997In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 35, no 9, p. 153-160Article in journal (Refereed)
    Abstract [en]

    The development of a sustainable sewerage system includes the utilisation of nutrients from human urine and faeces in agriculture. One strategy for developing a sustainable sewerage system is to handle urine separately and use it as a fertiliser. One important reason for this strategy is the fact that urine is the source of around 70% of phosphorus and around 90% of nitrogen in black wastewater (wastewater from water closets). However, experience from systems with urine separation is limited. In this study a urine separation system in an "ecological" village in northern Sweden has been investigated. The village consists of 17 self-contained houses and the number of inhabitants have varied around 55 persons. The sewerage system is equipped with urine separation toilets. Thus, the urine is intended to be collected separately and led through a sewer system to a collection tank for urine. However, the collected urine was found to be relatively diluted. This could to some extent be explained by errors in the construction of the toilet. However, the main reason for the dilution is probably leakage of water into the urine sewer system. The study also showed that less than about half of the nitrogen and phosphorus from human urine disposed of through the toilets of the village was successfully collected. Thus, the study shows that the successful operation of a urine separation system is very dependent on well-designed toilets and a user behaviour that promotes a high degree of separation.

  • 8.
    Hellström, Daniel
    et al.
    Luleå tekniska universitet.
    Kärrman, Erik
    Exergy analysis and nutrient flows of various sewerage systems1997In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 35, no 9, p. 135-144Article in journal (Refereed)
    Abstract [en]

    There is an increasing demand for more sustainable sewerage systems. An important tool in the analysis of the sustainability of a sewerage system is energy analysis. It is possible, by using an exergy analysis, to estimate the consumption of physical resources. In the present study, the demand on resources in the sewerage system of Bergsjon, a district of Goteborg, Sweden, was evaluated through exergy analysis. The case study included the existing system and two sewerage system alternatives. One important aspect of a sustainable sanitary system is nutrients recycling from sewage to agriculture. The exergy analysis has therefore been complemented with an analysis of the mass-flows of phosphorus and nitrogen. The study shows that the hypothetical calculated exergy consumption during operation will be lower in a system with local treatment and urine separation toilets compared with a conventional alternative. The amount of phosphorus that could be recycled is the same for the studied alternatives, but the amount of nitrogen that could be recycled is considerably higher for systems with urine separation techniques

  • 9.
    Kleidorfer, Manfred
    et al.
    University of Innsbruck, Unit of Environmental Engineering.
    Leonhardt, Günther
    University of Innsbruck, Unit of Environmental Engineering.
    Rauch, Wolfgang
    University of Innsbruck, Unit of Environmental Engineering.
    Identifiability analysis in conceptual sewer modelling2012In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 66, no 7, p. 1467-1474Article in journal (Refereed)
    Abstract [en]

    For a sufficient calibration of an environmental model not only parameter sensitivity but also parameter identifiability is an important issue. In identifiability analysis it is possible to analyse whether changes in one parameter can be compensated by appropriate changes of the other ones within a given uncertainty range. Parameter identifiability is conditional to the information content of the calibration data and consequently conditional to a certain measurement layout (i.e. types of measurements, number and location of measurement sites, temporal resolution of measurements etc.). Hence the influence of number and location of measurement sites on the number of identifiable parameters can be investigated. In the present study identifiability analysis is applied to a conceptual model of a combined sewer system aiming to predict the combined sewer overflow emissions. Different measurement layouts are tested and it can be shown that only 13 of the most sensitive catchment areas (represented by the model parameter 'effective impervious area') can be identified when overflow measurements of the 20 highest overflows and the runoff to the waste water treatment plant are used for calibration. The main advantage of this method is very low computational costs as the number of required model runs equals the total number of model parameters. Hence, this method is a valuable tool when analysing large models with a long runtime and many parameters

  • 10.
    Lagerkvist, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Geosciences and Environmental Engineering.
    Chen, Huiting
    Luleå University of Technology.
    Control of two step anaerobic degradation of municipal solid waste (MSW) by enzyme addition1993In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 27, no 2, p. 47-56Article in journal (Refereed)
    Abstract [en]

    The addition of cellulolytic enzymes to MSW has been tried under methanogenic and acidogenic conditions in 0.1 m3 landfill models. An enhanced degradation seems to follow the enzyme addition in both cases. During acidogenic conditions the observed conversion of cellulose was 42 and 29% respectively, with and without enzyme addition. The enzyme addition did not result in a change from methanogenic to acidogenic conditions. A similar conversion of VS can be achieved during methanogenic and acidogenic conditions; at the completion of this experiment the conversion of VS was in excess of 50% in the methanogenic models and somewhat lower than 40% in the acidogenic models (the latter still yielding strong leachates). The results of some standard waste-water analyses were compared and it is concluded that especially acid leachates may cause analytical problems.

  • 11.
    Leonhardt, G.
    et al.
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    D'Oria, M.
    Department of Civil, Environmental and Land Engineering and Architecture, University of Parma.
    Kleidorfer, M.
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Rauch, W.
    Unit of Environmental Engineering, Institute for Infrastructure Engineering, University of Innsbruck.
    Estimating inflow to a combined sewer overflow structure with storage tank in real time: Evaluation of different approaches2014In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 70, no 7, p. 1143-1151Article in journal (Refereed)
    Abstract [en]

    The performance assessment of storage tanks and combined sewer overflow (CSO) structures in sewer systems requires knowledge of the total inflow from the catchment during rainfall events. Many structures are, however, only equipped with sensors to measure water level and/or outflows. Based on the geometry of the tank, expressed as a level-storage relationship, inflow can be calculated from these data using a simple conceptual storage model. This paper compares a deterministic and a Bayesian approach for estimating the inflow to a CSO structure from measurements of outflows and water level. The Bayesian approach clearly outperforms the deterministic estimation which is very sensitive to measurement errors. Although computationally more demanding, the use of a simple linear storage model allows the online application of the Bayesian approach to repeatedly estimate inflow in short time intervals of a few minutes. The method could thus be used as an online software sensor for inflow to storage structures in sewer systems.

  • 12.
    Leonhardt, Günther
    et al.
    Unit of Environmental Engineering, Institute for Infrastructure, University of Innsbruck.
    Fach, Stefan
    Unit of Environmental Engineering, Institute for Infrastructure, University of Innsbruck.
    Engelhard, Carolina
    Unit of Environmental Engineering, Institute for Infrastructure, University of Innsbruck.
    Kinzel, Heiko
    Hydro-IT GmbH.
    Rauch, Wolfgang
    University of Innsbruck, Unit of Environmental Engineering.
    A software-based sensor for combined sewer overflows2012In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 66, no 7, p. 1475-1482Article in journal (Refereed)
    Abstract [en]

    A new methodology for online estimation of excess flow from combined sewer overflow (CSO) structures based on simulation models is presented. If sufficient flow and water level data from the sewer system is available, no rainfall data are needed to run the model. An inverse rainfall-runoff model was developed to simulate net rainfall based on flow and water level data. Excess flow at all CSO structures in a catchment can then be simulated with a rainfall-runoff model. The method is applied to a case study and results show that the inverse rainfall-runoff model can be used instead of missing rain gauges. Online operation is ensured by software providing an interface to the SCADAsystem of the operator and controlling the model. A water quality model could be included to simulate also pollutant concentrations in the excess flow

  • 13.
    Malmqvist, P A
    et al.
    Chalmers University of Technology.
    Palmquist, Helena
    Luleå tekniska universitet.
    Decision support tools for urban water and wastewater systems: focussing on hazardous flows assessment2005In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 51, no 8, p. 41-49Article in journal (Refereed)
    Abstract [en]

    The Swedish research programme Urban Water has developed a concept of a multi-criteria basis intended to support decision-making for urban water and wastewater systems. Five criteria groups were established for sustainability assessment of urban water systems: Health and Hygiene, Environment, Economy, Socio-culture, and Technology. Each criterion requires a set of indicators corresponding to quantifiable facts and figures, or qualitative data to comparatively assess the different alternatives in the decision process. The decision support process starts as a baseline study where the existing conditions are addressed. Alternative strategies of the future urban water system are developed and analysed by different tools and methodologies in assessing the five criteria groups. Eventually, the results and conclusions are integrated and synthesised into a basis for decision-making. As an example of a decision support basis for chemical safety, a barrier perspective was introduced to find out if and to what extent hazardous substances can be stopped, diverged, or transformed at various points in the wastewater system. A set of barriers was suggested, i.e. behaviour, systems design, process design, optional recipients, and organisational. The barrier approach was applied to two alternative municipal wastewater system designs--a combined wastewater system vs. a source separated system--analysing the fate of phosphorus, cadmium, and triclosan. The study showed that the combined system caused a higher substance flow to the receiving waterbody than the separated system. The combined system also brought more phosphorus and cadmium to the farmland than the separated system, but only half the amount of triclosan.

  • 14.
    Marsalek, J.
    et al.
    National Water Research Institute, Burlington, Ontario.
    Oberts, G.
    Emmons and Olivier Resources, Oakdale, Minnesota.
    Exall, K.
    National Water Research Institute, Burlington, Ontario.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Review of operation of urban drainage systems in cold weather: water quality considerations2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 11-20Article in journal (Refereed)
    Abstract [en]

    Cold climate imposes special requirements on urban drainage systems, arising from extended storage of precipitation and pollutants in the catchment snowpack, processes occurring in the snowpack, and changes in catchment surface and transport network by snow and ice. Consequently, the resulting catchment response and runoff quantity differ from those experienced in snow- and ice-free seasons. Sources of pollutants entering urban snowpacks include airborne fallout, pavement and roadside deposits, and applications of de-icing and anti-skid agents. In the snowpack, snow, water and chemicals are subject to various processes, which affect their movement through the pack and eventual release during the melting process. Soluble constituents are flushed from the snowpack early during the melt; hydrophobic substances generally stay in the pack until the very end of melt and coarse solids with adsorbed pollutants stay on the ground after the melt is finished. The impacts of snowmelt on receiving waters have been measured mostly by the snowmelt chemical composition and inferences about its environmental significance. Recently, snowmelt has been tested by standard bioassays and often found toxic. Toxicity was attributed mostly to chloride and trace metals, and contributed to reduced diversity of benthic and plant communities. Thus, snowmelt and winter runoff discharged from urban drainage threaten aquatic ecosystems in many locations and require further studies with respect to advancing their understanding and development of best management practices.

  • 15.
    Muthanna, Tone M.
    et al.
    Norwegian University of Science and Technology, Department of Hydraulic and Environment Engineering, Trondheim.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Thorolfsson, S.T.
    Norwegian University of Science and Technology, Department of Hydraulic and Environment Engineering, Trondheim.
    An evaluation of applying existing bioretention sizing methods to cold climates with snow storage conditions2007In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 56, no 10, p. 73-81Article in journal (Refereed)
    Abstract [en]

    Eight of the current sizing and design methods proposed for bioretention facilities were evaluated for rainfall runoff and snow storage volumes for a costal cold climate in Trondheim, Norway. The RECARGA bioretention infiltration model was used to compare the performance of the methods using 30 months of observed data from a pilot scale bioretention box. The surface areas, total ponding time, number and duration of overflow events, and snow storage volumes were compared. It was found that even in a costal cold climate with several intermittent melt cycles die snow storage requirements were an important design parameter, and if more than 25% of the total snow volume should stored this became the deciding design parameter

  • 16.
    Nyström, Fredrik
    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.
    Herrmann, Inga
    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.
    Treatment of road runoff by coagulation/flocculation and sedimentation2019In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 79, no 3, p. 518-525Article in journal (Refereed)
    Abstract [en]

    A laboratory investigation of the treatment potential of a coagulation process in the context of stormwater treatment was undertaken. The initial 25 L road runoff generated from four rain events was collected and subjected to a jar-testing regime with two commercial coagulants. The treatment effect was assessed by analysing the runoff before and after treatment for turbidity, suspended solids and metal content. The coagulation process resulted in particle and total metal reduction of more than 90% compared to 40% for only sedimentation. Up to 40% reduction of dissolved Cr, Cu and Pb was also observed compared to 0% for sedimentation. This study shows that coagulation may be a useful process for stormwater treatment systems when the treatment requirements are high.

  • 17.
    Pelkonen, Markku
    Laboratory of Environmental Engineering, Helsinki University of Technology.
    Upgrading oxygen transfer in the activated sludge process1990In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 22, no 7-8, p. 253-260Article in journal (Refereed)
    Abstract [en]

    The objectives were to get some information on the variation of the alpha factor and to study factors affecting oxygen transfer efficiency in fine-bubble aeration. Results from a 5 week continuous operation of a batch aeration column process show that the variation of the alpha factor was considerable in the aeration basin, especially at the inlet end. The variation follows a diurnal rhythm and the weekly variation is much smaller. The off-gas method was used to examine factors affecting oxygen transfer in process conditions. Regression models were constructed to describe the transfer process both on a semitechnical scale and on a full scale. The most important factors are the specific air flow rate, the respiration rate and the DO concentration. The enhancement in OTE through the respiration rate and the DO concentration is due to a biological mechanism. To optimize the transfer process it is necessary to maintain a high respiration rate and a sufficiently high DO concentration.The objectives were to get some information on the variation of the alpha factor and to study factors affecting oxygen transfer efficiency in finebubble aeration. Results from a 5 week continuous operation of a batch aeration column process show that the variation of the alpha factor was considerable in the aeration basin, especially at the inlet end. The variation follows a diurnal rhythm and the weekly variation is much smaller. The off-gas method was used to examine factors affecting oxygen transfer in process conditions. Regression models were constructed to describe the transfer process both on a semitechnical scale and on a full scale. The most important factors are the specific air flow rate, the respiration rate and the DO concentration. The enhancement in OTE through the respiration rate and the DO concentration is due to a biological mechanism. To optimize the transfer process it is necessary to maintain a high respiration rate and a sufficiently high DO concentration.--------------------------------------------------------------------------------

  • 18.
    Pelkonen, Markku
    et al.
    Helsinki University of Technology.
    Tenno, Robert A.
    Laboratory of Environmental Engineering, Helsinki University of Technology, Helsinki University of Technology.
    New control parameters and measurement techniques for the activated sludge process1993In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 27, no 5-6, p. 287-295Article in journal (Refereed)
    Abstract [en]

    An on-line oxygen uptake and CO2-production rate measurement system was used to analyse the biomass activity. CO2-production rate corresponded well with oxygen uptake rate in the carbon oxidation process. In the nitrification process the ratio CO2-prod./O2-consumed (r(q)) had a larger variation, but CO2-production had a good correlation with utilized COD; variation of the r(q)-value indicate differences in the auto-/heterotrophic oxidation balance. From this basis the oxygen uptake rate for carbon oxidation and nitrification can be separated. The comparison with two biomass determination methods based on ATP-analysis shows that for heterotrophic biomass the methods indicate clearly different changes of ATP, for nitrification process the results were more compatible. By combining the biomass and on-line measurements with biomass growth model based on IAWPRC-model equations reasonably good estimates were obtained. Best fit of model was in the nitrification process; by using VSS as the measure of biomass the fit was poor. The differences in the ATP-measurement results affect also the model coefficients.An on-line oxygen uptake and CO2-production rate measurement system was used to analyze the biomass activity. CO2-production rate corresponded well with oxygen uptake rate in the carbon oxidation process. In the nitrification process the ratio CO2-prod./O2-consumed (rg) had a larger variation, but CO2-production had a good correlation with utilized COD; variation of rg-value indicate differences in auto-heterotrophic oxidation and nitrification can be separated. The comparison with two biomass determination methods based on ATP-analysis shows that for heterophil biomass the methods indicate clearly different changes of ATP, for nitrification process the results were more compatible. By combining the biomass and on-line measurements with biomass growth model based on IAWPRC-model equations reasonably good estimated were obtained. Best fit of model was in the nitrification process; by using VSS as the measure of biomass the fit was poor. The differences in the ATP-measurement results affect also the model coefficients

  • 19.
    Pericault, Youen
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Risberg, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    Vesterlund, Mattias
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Energy Science.
    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.
    A novel freeze protection strategy for shallow buried sewer pipes: temperature modelling and field investigation2017In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 76, no 2, p. 294-301Article in journal (Refereed)
    Abstract [en]

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

  • 20. Reinosdotter, Karin
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Malmqvist, Per-Arne
    Comparison of the effects of using local and central snow deposits: a case study in Luleå2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 71-79Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to determine if an increased use of local land-based snow deposits would be more sustainable than the use of a central snow deposit. The study focused on transport related emissions, costs for transporting the snow, technical attendance, local effects, public acceptance, land use, effects on the recipient environmental control and potential for accidents. General information was obtained from an inventory regarding snow handling that was made in 14, geographically spread, Swedish municipalities during 2001. The comparison of costs for transporting snow and transport-related emissions was based on information gathered from the municipality of Luleå. The study showed that using local land-based snow deposits would decrease traffic-related emissions such as CO2, CO and NOx by 40% annually and would decrease the annual cost for transporting snow by nearly 80%. On the other hand local snow deposits may lead to an increased risk of accidents and to negative local effects such as delayed growing season, flooding and drainage problems. Available land for local snow deposits in the cities is hard to find, and is usually expensive. Therefore a combination of local and central snow deposits is likely to be the most realistic option.

  • 21. Reinosdotter, Karin
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Malmqvist, Per-Arne
    Chalmers University of Technology, Urban Water.
    Polycyclic aromatic hydrocarbons and metals in snow along a highway2006In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 54, no 6-7, p. 195-203Article in journal (Refereed)
    Abstract [en]

    Snow quality and its variations due to distance from the road were studied. Also, how the snow quality changes over time during the melting period was discussed. Snow samples were collected at three occasions during the winter of 2004. The samples were taken along a highway in the Luleå region, Sweden, with an average daily traffic load of 9,200 vehicles. Snow samples were taken perpendicular to the road and at different distances. The snow samples were analysed for metals and polycyclic aromatic hydrocarbons (PAH). Also, weather parameters such as temperature, precipitation, and wind speed and wind direction were measured. The highest total metal and PAH concentrations were found at the sample site closest to the road and at the end of the season. Before the melting period started, 42-57% of the total amount of metals and PAH were found in the first 1 m of the snow pack. This information could be valuable when one is discussing how to achieve sustainable snow-handling management.

  • 22.
    Sellgren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Some environmental consequences of water and energy conservation in the handling of mine tailings in sub-arctic regions1986In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 18, no 2, p. 141-149Article in journal (Refereed)
    Abstract [en]

    Great savings of energy and water can be obtained at concentrators if the tailings slurry is thickened more effectively and water is reused directly instead of being transported the long way around the disposal area. With direct circulation in sub-arctic regions, large amounts of heating energy can be recovered using a heat pump arrangement. The potential savings at a Swedish concentrator were estimated to be about 10-20 GWh per year, the majority of which would be savings in oil. In cold areas, temperature and hydrological conditions greatly influence spreading and dissipation mechanisms of pollutants released in the process. Monthly variations of the discharge to the recipient of a substance emitted in the process were simulated in an example. The degree of direct circulation in flotation of complex sulphide ores may be limited by water quality problems in the process. A mathematical model was developed and used to simulate the accumulation of a substance in the process for different degrees of direct circulation. Finally, a schematic layout of a simple aeration plant for recycled process water was outlined and some regional water-related problems were discussed

  • 23.
    Stenmark, Christer
    Luleå tekniska universitet.
    Alternative road construction for stormwater management in cold climates1995In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 32, no 1, p. 79-84Article in journal (Refereed)
    Abstract [en]

    A field study of an infiltration and detention facility in northern Sweden is presented. Streets in a housing area were reconstructed to increase the permeable area. Permeable asphalt was used covering a coarse fill material and swales (ditches) were constructed along both sides of the streets. The project will include studies of the water balance during different seasons, frost heave and frost penetration of the streets and the storm water quality. Due to the reduced infiltration capacity during snowmelt periods, detailed studies will be performed on components of the facility that are important for the disposal of meltwater. Some initial tests of the infiltration capacity of permeable asphalt in cold temperatures indicated sufficient capacity during snowmelt periods.

  • 24.
    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.

  • 25.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Dissolved and particle-bound substances in urban snow1999In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 39, no 12, p. 27-32Article in journal (Refereed)
    Abstract [en]

    In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Lulea, northern Sweden. Sampling sites were chosen in the city centre and in a housing area three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher.In order to create a picture of the pollutant pathways for snow in urban areas, snow samples were collected in the city of Lulea northern Sweden. Sampling sites were chosen in the city centre and in a housing area - three different sites in each area. Snow samples were collected during the whole winter of 1995. The results showed that the amounts of dissolved substances as percentages of the total amounts varied according to time, site and the type of substance. For the sites along the roadsides in the city centre, the amounts that were in solution were less than 1% of the lead, 2.5% of the phosphorus, 11% of the copper, and 18% of the zinc. For the site with no-traffic, the dissolved fractions were considerably higher

  • 26.
    Viklander, Maria
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Marsalek, J.
    National Water Research Institute, Burlington, Ontario.
    Malmquist, P-A
    Chalmers University of Technology, Urban Water.
    Watt, W.E.
    Queen's University, Department of Civil Engineering, Kingston, ON.
    Urban drainage and highway runoff in cold climates: conference overview2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 1-10Article in journal (Refereed)
    Abstract [en]

    This overview of research findings presented at the conference on urban drainage and highway runoff in cold climates starts with generation of urban runoff and snowmelt, followed by snowmelt and winter runoff quality, best management practices for urban snowmelt and winter runoff, and snow management in urban areas. Research on the urban hydrological cycle is lagging behind the needs in this field, particularly in terms of data availability. The current studies of winter urban runoff quality focus on road salts in the urban environment and their environmental effects. The needs for better source controls in salt applications, improved management of chloride-laden runoff, and selective adoption of environmentally safer alternative de-icers were reported. Adaptation of the conventional stormwater best management practices (BMPs) for winter operation remains a challenge. The first step in refining the existing BMPs for winter operation is to advance the understanding of their operation, as reported for some cases at the conference. Finally, snow management in urban areas may require local storage of fresh (unpolluted) snow and disposal of more polluted snow at central snow disposal sites.

  • 27. Westerlund, Camilla
    et al.
    Viklander, Maria
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Architecture and Water.
    Bäckström, Magnus
    Seasonal variations in road runoff quality in Lulea, Sweden2003In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 48, no 9, p. 93-101Article in journal (Refereed)
    Abstract [en]

    In regions with cold climate the urban drainage and highway runoff processes become much more complex, compared to temperate regions. Therefore, climatic conditions should be taken into account in planning and design of BMPs and snow handling strategies. In order to increase the knowledge of road runoff quality during melt and rain periods, respectively, measurements were carried out at a field site during a two-month period. The field site was situated at Sodra Hamnleden, a road with 7,400 vehicles/day, in the central part of Lulea. Runoff samples were analysed for suspended solids and heavy metals (Pb, Cu, Cd, Ni and Zn). The results showed that the concentrations of suspended solids, lead, copper and cadmium were higher for the melt period, compared to rain generated runoff on the catchment without snow, and the highest concentrations were found during the rain-on-snow events. The results indicate a flow dependent increase in the concentration of suspended solids during the melt period. A comparison of the total mass of suspended solids over a one-month period showed that the melt period produced about 3 times more suspended solids. Metal elements during melt period were more particulate bound as compared to the rain period characterised by a higher percentage of the dissolved fraction

  • 28.
    Zischg, Jonatan
    et al.
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Goncalves, Mariana L. R.
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Bacchin, Taneha K.
    Environmental Technology & Design, Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology, The Netherlands.
    Leonhardt, Günther
    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.
    van Timmeren, Arjan
    Environmental Technology & Design, Department of Urbanism, Faculty of Architecture and the Built Environment, Delft University of Technology, The Netherlands.
    Rauch, Wolfgang
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Sitzenfrei, Robert
    Unit of Environmental Engineering, University of Innsbruck, Austria.
    Info-Gap robustness pathway method for transitioning of urban drainage systems under deep uncertainties2017In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 76, no 5, p. 1272-1281Article in journal (Refereed)
    Abstract [en]

    In the urban water cycle, there are different ways of handling stormwater runoff. Traditional systems mainly rely on underground piped, sometimes named ‘gray’ infrastructure. New and so-called ‘green/blue’ ambitions aim for treating and conveying the runoff at the surface. Such concepts are mainly based on ground infiltration and temporal storage. In this work a methodology to create and compare different planning alternatives for stormwater handling on their pathways to a desired system state is presented. Investigations are made to assess the system performance and robustness when facing the deeply uncertain spatial and temporal developments in the future urban fabric, including impacts caused by climate change, urbanization and other disruptive events, like shifts in the network layout and interactions of ‘gray’ and ‘green/blue’ structures. With the Info-Gap robustness pathway method, three planning alternatives are evaluated to identify critical performance levels at different stages over time. This novel methodology is applied to a real case study problem where a city relocation process takes place during the upcoming decades. In this case study it is shown that hybrid systems including green infrastructures are more robust with respect to future uncertainties, compared to traditional network design.

  • 29.
    Ödegaard, H.
    et al.
    Norwegian University of Science and Technology (NTNU), Trondheim.
    Balmer, P.
    Chalmers University of Technology.
    Hanaeus, Jörgen
    Chemical precipitation in highly loaded stabilization ponds in cold clomates: scandinavian experiences1987In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 19, no 12, p. 71-77Article in journal (Refereed)
    Abstract [en]

    Results both from a pilot-plant investigation and from full-scale stabilization ponds operating with phosphate precipitation are presented. Since the removal of organic matter by coagulation is more important than that by biodegradation, the ponds may be heavily loaded. Biodegradation during winter can be improved by pond aeration, and chemical precipitation in an aerated pond may give a very good and stable effluent

1 - 29 of 29
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