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  • 1.
    Dienus, Olaf
    et al.
    Ryhov County Hospital, Medical Services, Clinical Microbiology.
    Sokolova, Ekaterina
    Chalmers University of Technology, Department of Civil and Environmental Engineering, Water Environment Technology.
    Nyström, Fredrik
    Ryhov Cty Hosp, Clin Microbiol, Med Serv; Linkoping Univ, Dept Clin & Expt Med.
    Matussek, Andreas
    Ryhov County Hospital, Medical Services, Clinical Microbiology.
    Löfgren, Sture M.
    Ryhov County Hospital, Medical Services, Clinical Microbiology.
    Björklund Blom, Lena
    Chalmers University of Technology, Department of Civil and Environmental Engineering, Water Environment Technology.
    Pettersson, Thomas J.R
    Chalmers University of Technology, Department of Civil and Environmental Engineering, Water Environment Technology.
    Lindgren, Per Eric
    Chalmers University of Technology, Department of Civil and Environmental Engineering, Water Environment Technology.
    Norovirus Dynamics in Wastewater Discharges and in the Recipient Drinking Water Source: Long-Term Monitoring and Hydrodynamic Modeling2016Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 50, nr 20, s. 10851-10858Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Norovirus (NoV) that enters drinking water sources with wastewater discharges is a common cause of waterborne outbreaks. The impact of wastewater treatment plants (WWTPs) on the river Göta älv (Sweden) was studied using monitoring and hydrodynamic modeling. The concentrations of NoV genogroups (GG) I and II in samples collected at WWTPs and drinking water intakes (source water) during one year were quantified using duplex real-time reverse-transcription polymerase chain reaction. The mean (standard deviation) NoV GGI and GGII genome concentrations were 6.2 (1.4) and 6.8 (1.8) in incoming wastewater and 5.3 (1.4) and 5.9 (1.4) log10 genome equivalents (g.e.) L-1 in treated wastewater, respectively. The reduction at the WWTPs varied between 0.4 and 1.1 log10 units. In source water, the concentration ranged from below the detection limit to 3.8 log10 g.e. L-1. NoV GGII was detected in both wastewater and source water more frequently during the cold than the warm period of the year. The spread of NoV in the river was simulated using a three-dimensional hydrodynamic model. The modeling results indicated that the NoV GGI and GGII genome concentrations in source water may occasionally be up to 2.8 and 1.9 log10 units higher, respectively, than the concentrations measured during the monitoring project

  • 2.
    Nyström, Fredrik
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Coagulation process characteristics and pollutant removal from urban runoff2019Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Many different stormwater control measures (SCMs) can be implemented in order to mitigate issues with polluted stormwater flows into receiving water bodies.  The treatment function of  SCMs is commonly based on the removal of particles by sedimentation, thereby also removing pollutants associated with particles. In recent years, more attention has been given to characterizing and understanding of different particle size fractions and their association with pollutants commonly found in stormwater. It has become increasingly clear that the smaller sized particles are very important pollutant transporters and should be considered when designing and implementing SCMs. However, the settling velocities for smaller sized particles are very low and may not be effectively removed in existing SCMs. One treatment process with a proven ability to enhance sedimentation is coagulation/flocculation, widespread in water and wastewater treatment, but with very few accounts of it being used in a stormwater context. This thesis aims to investigate the treatability of stormwater with a coagulation/flocculation process. This includes the determination of operating conditions, the dominating coagulation mechanism and the reduction efficiency of stormwater related pollutants. The objectives of the thesis were achieved in laboratory tests treating stormwater in a jar-testing procedure.

    An initial screening of primary coagulants and flocculant aids was conducted using an urban snowmelt mixture. Five of the chemicals were then selected for an extended testing regime which was setup up to determine the operating conditions where maximal turbidity reduction was attained by measuring the pH, conductivity, alkalinity and zeta-potential over the tested doses for each coagulant. Criteria used for chemical selection included high turbidity reduction, low dose requirement and low pH/alkalinity impacts.

    Charge reversal was observed at positive zeta-potential indicating that the dominating coagulation mechanism was charge neutralization. The content of turbidity/total suspended solids, total organic carbon, total metals and hydrocarbons by >90%. Dissolved copper was reduced by 40% on average, and the reduction rates for dissolved zinc were varying with up to a 300% increase, presumably due to changes in pH, leading to a higher mobility. Changes in the particle size distribution after coagulation/flocculation as compared to sedimentation indicated an effect on the size fraction corresponding to smaller particles.

    The performance of the coagulation/flocculation process was also tested on road runoff collected from a central road in Luleå with a high traffic intensity. Two coagulants were tested, iron chloride and pre-hydrolyzed aluminum chloride. Reduction rates for the total metal fraction were >90% on average for both coagulants, but for the dissolved metal fractions differences could be observed between the coagulants with the iron chloride resulting in higher reductions for dissolved chrome (57% compared to 34%) and copper (47% compared to 30%). Both products increased the dissolved fractions of nickel and zinc due to lower final pH.

  • 3.
    Nyström, Fredrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordqvist, Kerstin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Flocculation and membrane filtration of stormwater: laboratory experiments2016Konferensbidrag (Övrigt vetenskapligt)
  • 4.
    Nyström, Fredrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordqvist, Kerstin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Laboratory evaluation of coagulants for treatment of urban snowmeltManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The treatment effect and process characteristics of coagulation were investigated in urban snow at laboratory scale using jar tests. An initial screening of twelve coagulants and flocculant aids was carried out to find a selection of chemicals that efficiently reduced turbidity and suspended solids. Five coagulants were then further investigated and additional parameters measured (conductivity, alkalinity and ζ-potential). The urban snowmelt mixture was characterized by high, but variable, particle content and low alkalinity. In the jar tests, high treatment efficiency (>90% reduction of both turbidity and suspended solids) was achieved for all coagulants. For very low alkalinity waters, the use of a biopolymer such as chitosan may be advantageous due to minimal alkalinity consumption. Based on the occurrence of charge reversal for all chemicals investigated, the mechanism for coagulation was likely charge neutralization. Treatment effect occurred in the ζ-potential range of -14 to +1 mV depending on the coagulant used. Initial turbidity and the ζ-potential are interesting parameter candidates for dosing control in stormwater treatment applications.

  • 5.
    Nyström, Fredrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordqvist, Kerstin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Removal of metals and hydrocarbons from urban snowmelt by coagulation and flocculationManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The treatment efficiency of a coagulation/flocculation and sedimentation process was investigated in urban snowmelt. Five different coagulants were evaluated for their effectiveness in reduction of particle content, organic carbon, total and dissolved metals, hydrocarbon oil index, PAHs and if any changes occurred in the particle size distribution. The pollutants in the snow melt were mostly in the particulate phase, and for both oil index and PAHs characterized by the larger sized molecules. An iron chloride coagulant was the only coagulant that had an effect on the particle size distribution post-treatment, where the distribution was shifted towards larger particles. In terms of total metal removal, the performance for the coagulants were similar with above 90% removal on average. Dissolved Cu, was one of the metals found in the dissolved phase, and it was reduced by 40% by coagulation treatment. The iron chloride coagulant did increase the dissolved Zn, attributed to a larger drop in pH resulting in a higher ion mobility. Similarly, the reduction in organic content, both TOC/oil/PAH were above 90% for most coagulants.

  • 6.
    Nyström, Fredrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordqvist, Kerstin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation2017Ingår i: 14th IWA/IAHR International Conference on Urban Drainage: Conference Proceedings, 2017, 2017Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

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

  • 7.
    Nyström, Fredrik
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Nordqvist, Kerstin
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Herrmann, Inga
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Hedström, Annelie
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Viklander, Maria
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Arkitektur och vatten.
    Treatment of road runoff by coagulation/flocculation and sedimentation2019Ingår i: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 79, nr 3, s. 518-525Artikel i tidskrift (Refereegranskat)
    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.

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