Stockholm, Sweden
Stockholm, Sweden

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Morling S.,Sweco Environment | Plaza E.,KTH Royal Institute of Technology
Desalination and Water Treatment | Year: 2011

Many earlier publication presented the lowest temperature of 10°C as feasible for nitrification process. The article evaluates long-term experience with biological nitrogen removal at low temperatures (between 2 and 10°C), studied at four wastewater treatment plants operated with SBR-technology: Holbaek (Denmark), Nowy Targ (Poland), Nynäshamn and Skaulo (Sweden). Influence if nitrogen loads and COD/N ratio on nitrification rate was studied. Despite of operation at low temperatures during 3-4 months of the year good relation between the nitrogen load and the specific nitrification rate has been obtained. Long-term studies regarding nitrification, temperature and SRT demonstrated that the actually needed (aerated) SRT were lower than the normally recommended values. In some cases the nitrification was maintained at a lower efficiency even during non-aerated phases due to remaining free oxygen in the reactor that is used for nitrification. © 2011 Desalination Publications.


The large-scale geological structure of the crystalline rock at the proposed high-level nuclear waste repository site at Forsmark, Sweden, has been classified in terms of deformation zones of elevated fracture frequency. The rock between deformation zones was divided into fracture domains according to fracture frequency. A methodology to constrain the geometric and hydraulic parameters that define a discrete fracture network (DFN) model for each fracture domain is presented. The methodology is based on flow logging and down-hole imaging in cored boreholes in combination with DFN realizations, fracture connectivity analysis and pumping test simulations. The simulations suggest that a good match could be obtained for a power law size distribution where the value of the location parameter equals the borehole radius but with different values for the shape parameter, depending on fracture domain and fracture set. Fractures around 10-100 m in size are the ones that typically form the connected network, giving inflows in the simulations. The report also addresses the issue of up-scaling of DFN properties to equivalent continuous porous medium (ECPM) bulk flow properties. Comparisons with double-packer injection tests provide confidence that the derived DFN formulation of detailed flows within individual fractures is also suited to simulating mean bulk flow properties and their spatial variability. © 2013 Springer-Verlag Berlin Heidelberg.


Ulusoy I.,Hacettepe University | Ulusoy I.,Lund University | Dahlin T.,Lund University | Bergman B.,SWECO Environment
Hydrogeology Journal | Year: 2015

Managed aquifer recharge (MAR) is an efficient way to remove organic matter from raw water and, at the same time, reduce temperature variation. Two MAR sites were constructed by Karlskrona municipality on Johannishus Esker in Sweden. One of these sites, Vång, was monitored for electrical conductivity and electrical resistivity (using electrical resistivity tomography - ERT) during a 9-week tracer infiltration test. The aim of the monitoring was to map the pathways of the infiltrated water, with the overall goal to increase the efficiency of the MAR. ERT proved useful in determining both the nature of the esker formation and the water migration pathways. In Vång, the esker ridge follows a tectonically controlled paleo-valley. The fault/fracture zone in the bedrock along this paleo-valley was mapped. During the tracer test, the infiltrated water was detected in the area close to the infiltration ponds, whereas far-situated observation wells were less affected. For sequential infiltration and recharge periods in MAR, the timing of the well pumping is another important factor. Natural groundwater flow direction was a determinant in the infiltration process, as expected. ERT measurements provide supplementary data for site selection, for monitoring the functionality of the MAR sites, and for revealing the geological, hydrogeological and structural characteristics of the site. © 2014, Springer-Verlag Berlin Heidelberg.


Ulusoy E.,Hacettepe University | Ulusoy E.,Lund University | Dahlin T.,Lund University | Bergman B.,SWECO Environment
Hydrogeology Journal | Year: 2015

Managed aquifer recharge (MAR) is an efficient way to remove organic matter from raw water and, at the same time, reduce temperature variation. Two MAR sites were constructed by Karlskrona municipality on Johannishus Esker in Sweden. One of these sites, Vång, was monitored for electrical conductivity and electrical resistivity (using electrical resistivity tomography - ERT) during a 9-week tracer infiltration test. The aim of the monitoring was to map the pathways of the infiltrated water, with the overall goal to increase the efficiency of the MAR. ERT proved useful in determining both the nature of the esker formation and the water migration pathways. In Vång, the esker ridge follows a tectonically controlled paleo-valley. The fault/fracture zone in the bedrock along this paleo-valley was mapped. During the tracer test, the infiltrated water was detected in the area close to the infiltration ponds, whereas far-situated observation wells were less affected. For sequential infiltration and recharge periods in MAR, the timing of the well pumping is another important factor. Natural groundwater flow direction was a determinant in the infiltration process, as expected. ERT measurements provide supplementary data for site selection, for monitoring the functionality of the MAR sites, and for revealing the geological, hydrogeological and structural characteristics of the site. © 2014, Springer-Verlag Berlin Heidelberg.


There is a need to revise existing design methods for stormwater pollutant treatment, flow transport and detention facilities. The aim is to increase the accuracy in predicting the performance compared with design only based upon areal and volumetric functions and to optimize design by considering more site-specific data, receiving water quality criteria and forecasted climate effects. During the latest years, flow proportional concentration data from in- and outlets from wet ponds and constructed wetlands, have been compiled. Furthermore, other kind of data from the specific facilities have been compiled, such as areas, volumes, proportion of vegetation, outlet design details and length:width ratio. The parameters are used to revise design methods and are implemented in the operative stormwater and recipient software model StormTac. Design criteria and parameters for calculating design flow and sizing required detention volume are also presented. The climate effects on some of the studied parameters, e.g. design flow and inlet concentration, are discussed. The paper presents the climate factor based upon the hypothesis that it is a function of the design rain duration and reoccurrence time. © IWA Publishing 2014.


Edwards Y.,Swedish Cement and Concrete Research Institute | Emilsson T.,Swedish University of Agricultural Sciences | Malmberg J.,The Roof | Skog A.P.,Sweco Environment
WIT Transactions on Ecology and the Environment | Year: 2014

Eco neighborhoods with green infrastructure solutions are increasingly being prescribed today in Swedish cities for reducing and attenuating storm water runoff, increasing biodiversity, having a temperature moderating effect and for energy saving. Thus, contractors are simply required to build with green gardens on concrete decks, such as green roofs, green terraces, green courtyards and green complete neighborhoods. A lot of knowledge and experience is in fact lacking today, and consequences may therefore be devastating. If green system solutions are to be seen as an obvious choice in future settlements, and not as a problem, there must be clear guidelines and specifications that ensure a sustainable outcome. This is missing today. This paper reports a project aiming at bringing together researchers, government and industry to the collaborative development of new and attractive solutions for green roof gardens with consideration to the environment and high requirements for durability, materials, construction and energy efficiency. These solutions must also be adaptable to similar types of facilities, specific needs and environments. One such area concerns public land such as parks, streets and squares on concrete decks. Certification and tailored guidelines for different types of systems are being developed. The initiating part of this project clearly indicates that there is a need for better understanding, more research and long term monitoring/follow up of green roofs. Furthermore, a holistic approach is introduced to ensure that one good green roof function will not have severe negative effects on other functions. © 2014 WIT Press.


Morling S.,Sweco Environment | Franquiz A.,Nynashamn municipality | Mahlgren J.,Nynashamn municipality | Westlund A.,Sweco Environment
Water Practice and Technology | Year: 2014

A biological wastewater treatment plant, Nynäshamn treating municipal wastewater and septic sludge operated with a combination of sequencing batch reactor (SBR) units and constructed wetland is presented in this paper. The plant has to treat low temperature wastewater in winter time, still with demands for a biological nitrogen removal. Treatment results from a 13 year operation period are presented. Special attention was given to the nutrient removal during low temperature conditions. The combination of a SBR system along with classical chemical precipitation and a polishing step based on 'natural' extensive treatment has been a sustainable way to keep the discharge levels low. The combined treatment with SBR and the wetland at the Nynäshamn plant has resulted in improved discharge levels typically as follows (annual mean values); BOD7 3 mg/l, to be compared with the formal consent value of,15 mg/l, total P, 0.1 mg/l, to be compared with the formal consent value of,0.5 mg/l and total N 7 mg/l, to be compared with the formal consent value of,15 mg/l. It is also important to underline that the change of process train has resulted in a substantial saving of the precipitant agent for phosphorus removal. The needed dosage is now 50% of the previous dose, before the implementation of the SBR-units. © IWA Publishing 2014.


Van Praagh M.,Sweco Environment | Van Praagh M.,Lund University | Modin H.,Sweco Environment | Trygg J.,WSP Environmental
Waste Management | Year: 2015

This study aims to verify the effect of physically removing the outer surface of contaminated concrete on total contents and on potential mobility of pollutants by means of leaching tests. Reclaimed concrete from 3 industrial sites in Sweden were included: A tar impregnated military storage, a military tar track-depot, as well as concrete constructions used for disposing of pesticide production surplus and residues. Solid materials and leachates from batch and column leaching tests were analysed for metals, Cl, F, SO4, DOC and contents of suspected organic compounds (polycyclic aromatic hydrocarbons, PAH, and pesticides/substances for pesticide production such as phenoxy acids, chlorophenols and chlorocresols, respectively). In case of PAH contaminated concrete, results indicate that removing 1 or 5mm of the surface lead to total concentrations below the Swedish guidelines for recycling of aggregates and soil in groundwork constructions. 3 out of 4 concrete samples contaminated with pesticides fulfilled Swedish guidelines for contaminated soil. Results from batch and column leaching tests indicated, however, that concentrations above environmental quality standards for certain PAH and phenoxy acids, respectively, might occur at site when the crushed concrete is recycled in groundwork constructions. As leaching tests engaged in the study deviated from leaching test standards with a limited number of samples, the potential impact of the leaching tests' equipment on measured PAH and pesticide leachate concentrations has to be evaluated in future work. © 2015 Published by Elsevier Ltd.


Van Praagh M.,Sweco Environment | Van Praagh M.,Lund University | Modin H.,Sweco Environment
Waste Management | Year: 2016

Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH. > 12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values. © 2016 Elsevier Ltd.


PubMed | Lund University and Sweco Environment
Type: | Journal: Waste management (New York, N.Y.) | Year: 2016

Concrete samples from demolition waste of a former pesticide plant in Sweden were analysed for total contents and leachate concentrations of potentially hazardous inorganic substances, TOC, phenols, as well as for pesticide compounds such as phenoxy acids, chlorophenols and chlorocresols. Leachates were produced by means of modified standard column leaching tests and pH-stat batch tests. Due to elevated contents of chromium and lead, as well as due to high chloride concentrations in the first leachate from column tests at L/S 0.1, recycling of the concrete as a construction material in groundworks is likely to be restricted according to Swedish guidelines. The studied pesticide compounds appear to be relatively mobile at the materials own pH>12, 12, 9 and 7. Potential leaching of pesticide residues from recycled concrete to ground water and surface water might exceed water quality guidelines for the remediation site and the EU Water Framework Directive. Results of this study stress the necessity to systematically study the mechanism behind mobility of organic contaminants from alkaline construction and demolition wastes rather than rely on total content limit values.

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