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Sökning: WFRF:(Herrmann Inga 1978 )

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1.
  • Hamisi, Rajabu, 1978-, et al. (författare)
  • Reactive transport modelling of long-term phosphorus dynamic in the compact constructed   wetland using COMSOL Multiphysics
  • Ingår i: Ecological Engineering Journal.
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • A three-dimensional reactive transport model (RETRAP-3D) was developed by this study in the COMSOL Multiphysics®software to evaluate the long-term sorption capacity and mechanisms of dissolved reactive phosphorus removal in reactive adsorbent. The model coupledphysics interfaces for water flow, transport of reactive species, reaction kinetics for chemical compositions and biofilm development. Simulations were conducted for Polonite®, Filtralite P®, and Blast Furnace Slag mediaat fully saturated media, equilibrium miscible solution and isothermal heat transfer conditions. The model was validated using column experimental data ofsimilar media for application in constructed filter beds. The general modelling results showed good agreement with the measured breakthrough data. The most significant DIP retention capacity (P < 0.02) and longest residence time(1250 days) has been found for Polonite® and the most insignificant DIP retention for blast furnace slag (P > 0.54). The DIP removal was significantly correlated to factors of pH change, media characteristics, hydraulic dosage and retention times. These results demonstrate the reliability of the model as aflexible tool to predict the long-term performance of filter media and better understand processes within the system under various operational, weather and wastewater conditions.
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2.
  • Herrmann, Inga, 1978-, et al. (författare)
  • Discharge of indicator bacteria from on-site wastewater treatment systems
  • 2017
  • Ingår i: Desalination and Water Treatment. - : Desalination Publications. - 1944-3994 .- 1944-3986. ; 91, s. 365-373
  • Tidskriftsartikel (refereegranskat)abstract
    • Small-scale on-site wastewater treatment facilities present the risk of microbial pollution of groundwaterused for drinking water and surface water used for recreational purposes. This study assessedthe discharge of indicator bacteria, total coliform, Escherichia coli, intestinal enterococci and Clostridiumperfringens, by flow-proportional sampling from 12 full-scale on-site treatment systems featuringbiological treatment units (mainly sand filters) and alkaline filter beds for phosphorus treatment(P-filters). Correlations of effluent bacterial concentrations with pH, total and dissolved organic carbon,filter age and hydraulic load were evaluated. The bacterial concentrations in the effluents ofthe sand filters were considerable. The concentrations for excellent bathing water quality set in theEU bathing water directive, 200 and 500 colony forming units (cfu)/100 mL for intestinal enterococciand E. coli, respectively, were exceeded in three (intestinal enterococci) and one (E. coli) of the eightinvestigated sand filters. In one of the sand filters, effluent E. coli concentrations were high althoughno obvious malfunction of the filter was observed. In the effluent from the other investigated biologicaltreatment units (a trickling fibre filter, two units with attached growth treatment and one aeratedactivated sludge technique), bacterial concentrations were very high (75,000 cfu/100 mL of Clostridiumperfringens and 85,000 cfu per 100 mL of total coliform), possibly because of a shorter retention time ofthe wastewater in these facilities, missing aeration and little time between start-up and measurements.Three and four of the nine investigated P-filters exceeded excellent bathing water quality in coastalwaters as stipulated by the EU bathing water directive in respect of E. coli and intestinal enterococci,respectively.
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3.
  • Herrmann, Inga, 1978-, et al. (författare)
  • Markbaserad rening - design, funktion och bedömningkriterier vid tillsyn
  • 2021
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Markbaserade reningsanläggningar för avloppsvatten har använts länge i Sverige och anses som en robust och driftsäker reningsmetod. Kommunerna som ansvarar för tillsynen har vid inspektionsbesök av anläggningar observerat olika brister i sådana markbaserade anläggningar, t.ex. förhöjd slamförekomst i slamavskiljare, fördelningsbrunn, spridarledningar och/eller luftningsrör, för höga vattennivåer i delar av anläggningen och/eller problem med ventilation. Dessa problem har också uppmärksammats i olika projekt. Det är dock generellt svårt att bedöma huruvida dessa brister har en negativ påverkan på reningsanläggningens funktion. Det finns ett behov av ökad kunskap om när en markbaserad anläggning fungerar eller inte och hur detta ska bedömas, både för att en anläggning inte ska dömas ut i onödan och för att en anläggning som inte fungerar tillfredsställande får rätt typ av åtgärd.I detta projekt undersöktes design-, funktions- och tillsynsprinciper för markbaserade anläggningar med hjälp av litteraturstudier och intervjuer. Syftet var att bidra till utformning av relevanta bedömningskriterier för markbaserade reningsanläggningar som kan användas vid prövning och tillsyn. Målen var att:- granska litteraturen inom markbaserad rening för att lista viktiga faktorer som påverkar funktionen,- jämföra svenska dimensioneringskriterier för slamavskiljare och infiltrationer med kriterier som används i andra länder (Norge och USA),- beskriva hur tillsyn av markbaserade anläggningar genomförs hos kommuner som är aktiva inom tillsyn,- belysa hur olika kommuner resonerar angående bedömningen av olika typer av brister (i detta mål ingår att bedöma hur allvarliga olika typer av brister är – det vill säga om bristerna kräver en uppföljning i form av föreläggande eller förbud eller om det räcker med information eller enklare uppföljning – och hur pass stor samstämmighet som finns mellan olika kommuner vid bedömning av bristers allvarlighet),- uppmärksamma svårigheter med att bedöma funktionen i markbaserade anläggningar och peka ut framtida områden som behöver vidare arbete, samt att- sammanfatta hur tillsyn bedrivs i andra länder och resonera kring vilka lärdomar som kan dras därur.
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  • Herrmann, Inga, 1978-, et al. (författare)
  • Slutrapport av projekten "Fosforfällor för små avlopp - hur länge fungerar de?" och "Bakterieutsläpp från små avlopp"
  • 2017
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Små enskilda avloppsanläggningar i Sverige består ofta av en slamavskiljare med markbädd eller infiltration. I områden med hög skyddsnivå har på senare år ett stort antal fosforfilter installerats. Syftet med denna studie var att undersöka markbäddars och fosforfilters förmåga att reducera halten bakterier och fosfor i avloppsvattnet. Avloppsanläggningar i Västerbotten, Norrbotten och Norrtälje kommun identifierades och inspekterades. Prover togs mellan september 2015 och september 2016 från tolv avloppsanläggningar, åtta markbäddar och nio fosforfilter. Provtagning skedde minst tre gånger vid varje anläggning, och varje provtagningstillfälle varade cirka 3–4 timmar då det togs två stickprover från slamavskiljarens tredje kammare alternativt från fördelningsbrunnen, samt två flödesproportionella samlingsprover efter den biologiska reningen (det vill säga efter markbädden eller biosteget i minireningsverket) och efter fosforfiltret. I proverna mättes pH, mängden suspenderat material, temperatur, indikatorbakterier (E. coli, totala koliforma, intestinala enterokocker och Clostridium perfringens/C. perfringens), halten löst och total fosfor, halten löst och totalt organiskt kol (DOC, TOC) samt BOD. Spårämnesförsök genomfördes i tre fosforfilter med färgen rhodamin. 22 av de 34 inspekterade avloppsanläggningarna (65 procent) lämpade sig inte för flödesproportionell provtagning, vilket visar på svårigheten med att kontrollera funktionen av små avloppsanläggningar med hjälp av provtagning. Nio av 21 inspekterade fosforfilter lämpade sig inte för provtagning på grund av att det inte fanns något vattenflöde genom filtret, vilket indikerar att filtren inte fungerade som avsett. I utloppen från tre av de åtta undersökta markbäddarna var medelkoncentrationen intestinala enterokocker högre än badvattendirektivets gränsvärde för inlandsvatten med utmärkt vattenkvalitet. För E. coli-koncentrationer var detta fallet bara i en enda markbädd, men detta trots att det utgående vattnet var klart och hade TOC koncentrationer på en acceptabel nivå. Det här visar att bakteriekoncentrationer kan vara höga även om markbädden ser ut att fungera. Efter de nio undersökta fosforfiltren var bakteriekoncentrationen särskilt hög efter fosforfilter utan markbädd som förbehandlingssteg. I flera fall översteg koncentrationerna gränsvärdet för utmärkt badvattenkvalitet enligt badvattendirektivet; i tre fosforfilter med avseende på E. coli och i fyra fosforfilter med avseende på intestinala enterokocker. Medelkoncentrationen av E. coli-bakterier reducerades signifikant (p = 0,044) i fosforfiltren, vilket tyder på att fosforfilter kan tjäna som ett reningssteg som ytterligare reducerar bakterier. Detta kunde dock inte påvisas för intestinala enterokocker, totala koliforma eller C. perfringens. Koncentrationen av koliforma bakterier var beroende av fosforfiltrets hydrauliska belastning, vilket tyder på att flödesregimen och vattnets uppehållstid i filtret är viktiga parametrar som påverkar bakteriereduktionen. Både för markbäddarna och för fosforfiltren fanns ett samband mellan koncentrationen av indikatorbakterierer och utloppskoncentrationen av TOC och DOC, vilket tyder på att en högre halt av organiskt kol i utgående vatten visar på en sämre bakteriereduktion. Två av de åtta undersökta markbäddarna visade på god fosforreduktion som uppgick till 70 procent (slamavskiljare exkluderad) vilket krävs vid normal skyddsnivå enligt nuvarande regelverk. Fosforreduktionen i tre andra markbäddar var lägre (21–29 procent). Övriga tre markbäddar kunde inte betraktas vara godtagbara reningsanläggningar eftersom det troligtvis skedde en betydande inströmning av vatten in i dessa markbäddar med utspädning som följd. Den högsta koncentrationen av fosfor i utgående vatten från en markbädd var omkring 15 mg/l. Dock var utgående fosforkoncentrationer från de undersökta markbäddarna endast i fyra av åtta fall så höga (>2mg/l) att ett efterföljande fosforfilter skulle vara meningsfullt. Därför är det viktigt att markbäddar med efterföljande rening i fosforfilter byggs med tätskikt för att undvika in- och exfiltration. Fem av de nio utvärderade fosforfiltren reducerade (tillsammans med den biologiska förbehandlingen) mer än 90 procent av den inkommande fosforn från slamavskiljaren. Det betyder att de klarade reningskravet för fosfor i områden med hög skyddsnivå. Två av filtren uppvisade utgående koncentrationer av totalfosfor på 1–3 mg/l och den högsta utgående medelkoncentrationen var 4,4 mg/l. I anläggningar med biologiska behandlingsenheter som inte var markbäddar stod fosforfiltren för merparten av fosforavskiljningen. Fosforreduktionen i fosforfiltren korrelerade med pH i utgående vatten från filtren, med en beräknad korrelationskoefficient på 74 procent, vilket indikerar att pH kan användas som indikator på filtrets funktion. Dock visade resultaten också att fosforfilter med liknande pH-värde (nära 9) kan skilja sig mycket med avseende på fosforreduktion. Koncentration av organiskt kol eller fosfor i inkommande vatten till fosforfiltren kunde inte korreleras till filtrens fosforreducerade förmåga. En hög hydraulisk belastning påverkade dock fosforfiltrens funktion negativt. Liknande effekt hade filtrets ålder, om än inte lika tydligt. De preliminära resultaten från spårämnesförsöken indikerar att de fosforfilter som hade längre uppehållstid också hade högre fosforavskiljning än filter med kortare uppehållstid.
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8.
  • Herrmann, Inga, 1978-, et al. (författare)
  • Steel slag used in landfill cover liners: laboratory and field tests
  • 2010
  • Ingår i: Waste Management & Research. - 0734-242X .- 1096-3669. ; 28:12, s. 1114-1121
  • Tidskriftsartikel (refereegranskat)abstract
    • Stricter rules for landfilling within the EU have led to the closure of many landfills and a need for large amounts of cover liner materials. Therefore, the potential utilization of mixtures of electric arc furnace slag (EAFS) and ladle slag (LS), which are currently deposited in landfills, as a material for use as landfill liner was investigated. Laboratory analyses showed the mixtures to have similar compression strength to that of high-strength concrete and low hydraulic conductivity (<10-11 m s-1 in some cases). However, both their hydraulic conductivity and compaction properties were strongly affected by the time between adding water to the mixtures and compacting them (tests showed that a delay of 24 h can lead to an increase in hydraulic conductivity, so it should be compacted as soon as possible after mixing the material with water). In addition, the performance of a cover liner constructed using EAFS and LS was studied in a 2-year field trial on a landfill for municipal solid waste, in which the average amount of leachate collected from ten lysimeters was only 27 L m-2 year-1, easily meeting Swedish criteria for the permeability of covers on non-hazardous waste landfills (≤50 L m-2 year-1). Thus, the material seems to have promising potential for use in barrier constructions.
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11.
  • Herrmann, Inga, 1978-, et al. (författare)
  • Treatment of Phosphorus and Bacteria in Filters used for On-Site Sanitation in Cold Climate
  • 2016
  • Konferensbidrag (refereegranskat)abstract
    • Swedish rural on-site wastewater facilities need to reduce the phosphorus (P) concentrations in the wastewater to prevent eutrophication of the Baltic Sea, as well as the bacteria concentrations to comply with EU standards for bathing water quality. The aim of this study was to investigate two different on-site filter systems at full-scale, sand filters and (often subsequently used) alkaline P filters towards their performance to treat P and bacteria from domestic wastewater. Flow-proportional composite samples were taken from five sand filter beds and two P filters. Four of the five investigated sand filters considerably reduced the concentration of total P in the wastewater. However, infiltrating soil / ground water may have diluted the effluents. The investigated P filters varied in performance. While one of them treated P effectively, the other one performed poorly, probably due to old age and clogging. Low inlet P concentrations impeded the general assessment of the P filters’ efficiency. Concentrations of four indicator bacteria, intestinal enterococci, E. coli, total coliforms and C. perfringens, were considerably reduced in four of the five investigated sand filter beds. Bacteria removal in the two investigated P filters was difficult to assess because of low bacteria concentrations in the influents.
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12.
  • Isaksson, Frida, et al. (författare)
  • Greywater reuse for different purposes in Sweden : A literature review
  • 2023
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Globally, water demands are increasing as a result of e.g., population growth and a warmer climate; at the same time freshwater supplies are becoming scarcer. Also in parts of Sweden where water shortage historically has not been a concern, the availability of freshwater for potable water use is declining, especially in the summer. As a result, alternative water management strategies are receiving increased attention in an effort to reduce the pressure on potable water sources. One strategy is the treatment, recirculation and re-use of greywater, a type of water that can be collected in source-separating wastewater systems. Hence, the aim of this literature review was to provide knowledge necessary to understand how greywater can be treated, recycled and re-used in the society, with an emphasis on reuse in Sweden. The review covers different aspects including greywater characteristics, greywater treatment processes, legal frameworks and guidelines on greywater re-use, global examples as well as summary of findings from sustainability analyses conducted on greywater re-use systems.Greywater makes up 75–90% of the total domestic wastewater volume and thereby represents an important source for water reuse in systems with source-separating wastewater systems. Data of the quantity of greywater produced in households globally and in Sweden vary. According to Swedish studies, one person may produce between 66 to 150 l/d. Additionally, research indicates that greywater contains less pathogens and nutrients compared to mix wastewater due to the separation of greywater from blackwater, which in turn contains the human excreta. However, the concentrations of measured parameters vary significantly between different areas. Therefore, in order to ensure the quality of greywater, site-specific measures are necessary.Studies have been conducted on different greywater treatment methods for non-potable re-use, with biological and filtration techniques receiving the most attention. However, it is challenging to make generalizations about the optimal treatment techniques based on the end-usage, due to the variation in greywater characteristics between sites. In addition, this review shows that there is a lack of legal guidance for greywater reuse, which makes it more challenging for practitioners to understand what levels of treatment that are required before the reclaimed water can be reused in used in society. The review also shows that further sustainability analyses should be conducted on greywater reuse systems, in order to understand their benefits more comprehensively.
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Applicability of using sedimentation and membrane filtration for stormwater treatment
  • 2021
  • Konferensbidrag (refereegranskat)abstract
    • Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid arsenic, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology has shown acceptable treatment ability in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and a membrane process with different pore sizes and pulsatile flow (fluid flow with periodical variation) were evaluated with respect to separation of pollutants from a snowmelt mixture. For the aim of this research work, polyether sulfone nanofiltration and ultrafiltration membranes (PES NF, UF membrane) were used to assess the ability of the overall process to postpone fouling and treat the snowmelt mixture. The variation of pulse frequency was chosen between 0 and 2 Hz. A peristaltic pump with a constant rotational velocity of 220 rpm was used in all the experiments. Sedimentation as pre-treatment method was investigated in pre-experiments and it was shown that a variation in sedimentation time between 0.5-1 hours did not affect the treatment ability of the process. Therefore, 0.5 hour of sedimentation time was chosen in order to reduce the experimental run time. The experimental runs will be carried out during the winter period Feb-April 2021. The concentration of TSS, pH, total and dissolved metals and chloride, as well as the particle size distribution, turbidity and volume of clean water achieved in each experimental run is measured. The results from these experiments will give valuable information about treatment efficiency, if pulsatile flow increases the treatment performance as well as knowledge about the clogging process of the filter.
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Enhancing stormwater treatment through ultrafiltration: impact of cleaning chemicals and backwash duration on membrane efficiency
  • 2023
  • Ingår i: Water Reuse. - : IWA Publishing. - 2709-6092 .- 2709-6106. ; 13:4, s. 634-646
  • Tidskriftsartikel (refereegranskat)abstract
    • The effect of chemical cleaning and regular backwashing on the efficiency of an ultrafiltration membrane fouled during stormwater treatment was studied. Increasing backwash time from 30 to 60 s resulted in an increase in productivity by 20%. However, the productivity was highest when a backwash time of 45 s was used (3% higher than using 60 s). Chemical cleaning was carried out using an alkaline solution (NaOH with or without NaOCl) followed by acid washing with HCl. The addition of NaOCl to the cleaning chemical did not significantly increase the efficiency of chemical cleaning, and the average pure water permeability increase was 97 ± 13 LMH bar−1 after chemical cleaning with NaOH followed by HCl and 117 ± 15 LMH bar−1 after chemical cleaning with NaOH + NaOCl followed by HCl, on average. In addition, reversibility after chemical cleaning was 96 ± 67%, on average. The result from scanning electron microscopy showed that at the end of the experiments, inorganic foulants existed in both the inner layer (feed side) and the outer layer (permeate side) of the membrane.
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Stormwater treatment using an ultrafiltration membrane and pulsatile fluid flow
  • 2023
  • Ingår i: Urban Water Journal. - : Taylor & Francis. - 1573-062X .- 1744-9006.
  • Tidskriftsartikel (refereegranskat)abstract
    • A polymeric ultrafiltration (UF) membrane was used for stormwater treatment, with the focus on evaluating the increase in the membrane process productivity by adding pulsatile fluid flow to UF membrane treatment. Sedimentation and sieving were used as pre-treatment. The result showed that increasing the pulse frequency from 0 to 4 Hz increased productivity from -6.6 to 82 LMH. UF membrane removed suspended solids, oil and turbidity below detection limit. The UF membrane also separated total coliforms, E. coli and P. aeruginosa below detection limit. Total organic carbon (TOC) was reduced by between 70 and 91%. In addition, the UF membrane was able to reduce BOD7 and COD to below 7 mg/L in the permeate. According to the US EPA, WHO, and national regulations in Canada,  Japan, and South Korea, treated stormwater can be used for flushing toilets and streets irrigation and agricultural use. 
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Stormwater treatment using membrane filtration with pulsatile fluid flow
  • 2021
  • Konferensbidrag (refereegranskat)abstract
    • Stormwater runoff is one of the most important contributor of pollutants to natural waters. Therefore, separation of pollutants from stormwater runoff before entering the receiving waters is an important issue. Nitrogen (ammonium, nitrite, nitrate, total nitrogen), phosphorus (organic and inorganic), metals (Fe, Cd, Zn, Pb, As, Al, metalloid As, Cr, Cu, Ni in total, dissolved and truly dissolved form) are main compounds that are contained in various concentrations in the runoff and should be separated. Various methods have been used for stormwater treatment. Membrane technology is applied in water and wastewater industries1, but is not yet used for treatment of stormwater. Ceramic, polymeric and metallic membranes have been used in other research studies in order to optimise removal efficiency for separation of particulate, colloidal and dissolved substances in runoff. To prevent fouling, which is the major problem in membranes and to decrease the operational cost, use of a proper pre-treatment is helpful 2–4, as is periodical cleaning of the membrane surface 5,6. This process can be further assisted by using membranes with larger pore size (microfiltration, ultrafiltration) than nanofiltration and reverse osmosis membranes which have smaller pore size but higher removal efficiency. In this study, sedimentation was used as a pre-treatment method and an ultrafiltration membrane process and pulsatile flow were evaluated with respect to separation of pollutants from snowmelt mixture. A bench-scale membrane unit was used with a polyether sulfone ultrafiltration membrane (PES/PVP UF membrane) to assess the efficiency of the process and to evaluate if pulsatile flow at different pulse frequencies (0 and 4 Hz) can postpone fouling. The feed and permeate was sampled and analysed on the concentration of TSS, pH, total and dissolved metals and chloride content, as well as the particle size distribution, TOC, turbidity and oil index. The volume of permeate achieved in each experimental run was monitored. The results from these experiments showed that by increasing pulse frequency from 0 to 4 Hz, the productivity of membrane increased from 13.5% to 65.5%. In addition, TOC removal increased from 70% to 87%. Regardless of pulse frequency the ultrafiltration membrane set-up removed TSS, particles and oil fractions completely. Dissolved As, Cd, Cu, Cr, Ni, Pb and P were reduced by 16, 12.6, 11.8, 23.5, 21, 44 and 73.1%, respectively.
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Stormwater treatment using ultrafiltration – Effect of cleaning chemical and backwash time on membrane efficiency
  • 2022
  • Konferensbidrag (refereegranskat)abstract
    • Stormwater runoff is known as one of the main contributors of pollutants which is often discharged untreated to the water bodies and causes environmental risk [1]. Membrane treatment may be a good option for treatment of heavily polluted stormwater as it can also remove small particles and colloids that are not normally captured in typical stormwater facilities such as ponds, wetlands, etc. However, fouling in membranes is challenging to control. Application of a pre-treatment prior to the membrane process might help to postpone fouling [2]. In addition, a proper combination of backwash and chemical cleaning for the membrane is essential but this has not yet been studied specifically for stormwater runoff treatment with membranes. In this study, a combination of ultrafiltration PVP/PES membrane with pulsatile fluid flow was used for separation of pollutants from stormwater. Sieving was considered as pre-treatment. In addition, a combination of backwash and chemical cleaning was used to assess reversibility, flux recovery and productivity of the membrane. The results showed that by increasing backwash time from 30 to 60 s, the reversibility and flux recovery increased from 26% to 75% and 55% to 87%, on average and also resulted in 20% increase in productivity. Cleaning chemically with alkaline solution (NaOH, pH=12), followed by acidic solution (HCl, pH=2), had a good impact on removing foulants from membrane surface. According to the experiments, addition of NaOCl to the alkaline solution did not have significant effect on pure water flux recovery. From environmental point of view, using NaOCl is not recommended [3].
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  • Kaykhaii, Saida, 1989-, et al. (författare)
  • Stormwater treatment with ultrafiltration: Characterisation of backwash water : [Traitement des eaux pluviales par ultrafiltration: Caractérisation deseaux de rétrolavage]
  • 2023
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • Backwash water is an integral part of membrane treatment, normally making up between 2 and 10 % of the clean water production which constitutes a large volume on an industrial scale. To identify suitable treatment or disposal methods for backwash water, it is important to understand the characteristics of the backwash water and what contaminants it contains. In this study, the backwash water from an ultrafiltration membrane process for stormwater treatment was analysed. Concentrations of TSS and TOC were 2.4 and 24 times higher in the backwash water than the influent stormwater. The concentration of particulate and dissolved (<0.45µm) metals in the backwash water was high, for example, the average concentration of total Cu and Cr was 742 ± 215 and 737 ± 243 µg/L. In addition, the average concentration factors for Cu and Cr were 29 ± 9 and 41 ± 15.9. Methods such as coagulation, electrocoagulation and evaporation could be used to further treat backwash water. The residue fraction would contain high concentrations of metals that need to be disposed or could potentially be a good resource for metal recovery in the future.
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  • Kaykhaii, Saida, 1989- (författare)
  • Urban Stormwater Treatment with Ultrafiltration and Pulsatile Fluid Flow
  • 2023
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Stormwater can be a potential water resource if it is treated, and the quality meets the demand, depending on the application. Various nutrients and pollutants, for example microorganisms can enter stormwater and can vary depending on time and place, as the contaminants come from different sources. Sometimes the quality of stormwater can also deteriorate during its collection and storage. Therefore, the treatment of stormwater could be necessary before reuse and before discharge into the environment. Various treatment methods exist for this purpose. Ponds, wetlands, and bioretention systems are used in various countries to remove pollutants from stormwater. In addition to these methods, the use of membranes for stormwater treatment has become of interest.The application of membrane technology in new areas such as stormwater treatment requires a great deal of research to evaluate the potential opportunities and challenges. Research has been conducted to separate one or a few pollutants from stormwater using membranes. However, more research is needed to evaluate the applicability of using membranes for stormwater treatment, and their challenges and advantages. For this purpose, three experimental studies have been carried out. Polluted snow along a road was collected and treated using an ultrafiltration membrane. To prevent any damages to the membrane, a pretreatment step was included before the membrane process. It was of interest to evaluate the membrane process ability for treating snowmelt and to evaluate the potential for water reuse depending on regulations in different countries. Another objective was to investigate the productivity of the membrane process and try to improve it by adding pulsatile fluid flow to the experimental set-up. To investigate membrane cleaning, backwashing was carried out at regular intervals, and different backwash times and two chemical cleaning combinations were used. In addition, the fouling layer on the membrane was studied using a scanning electron microscope. Afterwards, the quality of the backwash water from the membrane cleaning was analyzed, which may be helpful in the future when looking for a suitable method to recycle the backwash water.When evaluating pulsatile fluid flow, the productivity of the membrane process increased significantly as the frequency of pulses increased (from -6.6 to 82 L/m2/h). The treated snowmelt mixture was of high quality and could be used for various applications, such as wetland maintenance, toilet flushing, and other municipal use. If the treated stormwater is disinfected, it can also be reused as drinking water. In this study, the optimal backwash duration was found to be 45 s in relation to productivity, although the backwash efficiency and permeability were higher with a backwash time of 60 s. The use of chemicals (NaOH with or without NaOCl followed by HCl) could restore the pure water permeability of the membrane to 107 L/m2/h/bar-1, in average. The pure water reversibility after chemical cleaning was 96% on average. Analysis of the backwash water showed that it is a concentrated solution of stormwater pollutants. TOC concentration was 24 times higher than pretreated stormwater. In addition, the backwash water contained significant concentrations of particulate metals and the concentration factor for various metals varied between 15 to 40.
  •  
20.
  • Klapp, Rasmus, 1990-, et al. (författare)
  • The French two-stage vertical flow constructed wetland in subarctic climate
  • 2022
  • Ingår i: 17th International Conference on Wetland Systems for Water Pollution Control: Conference Proceedings. - : IWA Publishing. ; , s. 579-580
  • Konferensbidrag (refereegranskat)abstract
    • Conventional small wastewater treatment plants in Sweden produce a sludge that needs to be collected and transported long distances to a centralised treatment facility. As many of these small plants are old and need replacement, the question arises weather a more sustainable solution is possible. The French two-stage vertical flow constructed wetland (VFCW) is a method where very little sludge handling is required, as the sludge is treated on-site. Therefore, this study aims to investigate cold climate performance of such a system in northern Sweden. A pilot-scale VFCW was built and sampled for BOD, nutrients and microplastics since November 2021. Results indicate that treatment performance is adequate and that microplastic can also be treated.
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21.
  • Lehtoranta, Suvi, et al. (författare)
  • Circular Economy in Wastewater Management—The Potential of Source-Separating Sanitation in Rural and Peri-Urban Areas of Northern Finland and Sweden
  • 2022
  • Ingår i: Frontiers in Environmental Science. - : Frontiers Media S.A.. - 2296-665X. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • Current practices in wastewater management lead to inefficient recovery and reuse of nutrients and can result in environmental problems. Source separation systems have been shown to be an efficient way of recovering nutrients and energy from wastewaters, both in rural and urban context. Studies on nutrient recovery potential and life cycle impacts of source separation systems are mainly limited to small systems (for example a few households) while the impacts of upscaling source separation to a regional level have hardly been studied, especially in sparsely populated areas where the cost of the connection to a main treatment plant is higher. This study examines the regional nutrient balance of two source separation scenarios—black water separation and urine diversion—and compares them to the existing conventional wastewater system. The analysis comprises three sparsely populated regions of northern Finland and Sweden, including rural, peri-urban and urban areas. In addition, climate impacts are assessed based on existing life cycle assessment (LCA) studies. According to the results, by source separation it is possible to achieve a significant increase in the recovery rate of phosphorus (41–81%) and nitrogen (689–864%) compared to the conventional system. Depending on the region up to 65% of the mineral phosphorus and 60% of mineral nitrogen fertilisers could be theoretically replaced. Furthermore, the climate and eutrophication impacts would decrease with the implementation of such systems, but an increase in acidification may occur. However, even if the benefits of source separation systems are undisputed in terms of nutrient recovery, the implementation of such systems would to a large extent require an entire system change of the wastewater treatment sector and a wide paradigm change towards a circular economy.
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22.
  • Milovanovic, Ivan, 1990- (författare)
  • Components for area-efficient stormwater treatment systems
  • 2021
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • With progressing urbanisation, treatment of urban stormwater is a vital issue that should be addressed to ensure good water quality in receiving water bodies. Treatment may be performed near the source, with different filter systems using various filter materials, or by using an end-of-pipe method, e.g. a stormwater pond. One constraint in the urban environment is the lack of available space in developed areas, where stormwater treatment facilities are needed the most. Methods developed to treat the stormwater runoff have been the focus of previous studies but the increasing standards of water quality and increasing land constraint pressures demand the further development of stormwater treatment systems. Both laboratory and field experiments are necessary to understand and improve the treatment processes as well as to evaluate how the implemented methods perform under field conditions. The aim of the thesis was to increase the knowledge about the components in stormwater treatment systems that can be used in area-efficient treatment facilities. In order to compare four potential stormwater filter materials (peat, bark, air-blown polypropylene and milkweed), column experiments were carried out using synthetic stormwater that simulated road runoff. Experiments were carried out to evaluate the impacts of the ageing of synthetic stormwater quality during laboratory testing, including dissolved metal concentrations and their impact on the estimation of filter efficiency. In a field study, a full-scale application of a zeolite filter installation was investigated, with a focus on service life and the efficiency of treating copper roof runoff. In order to further investigate a novel sedimentation device, a bottom grid structure (BGS), promoting sediment settling in a smaller area of a stormwater pond, a hydraulic modelling study was conducted to investigate the impact of the cell geometry of the structure on sediment settling and the impact of the structure on pond maintenance and sediment resuspension.  The column tests of four different filter materials showed that bark and peat had higher treatment efficiency for dissolved metals than milkweed and polypropylene, with the order of efficiency being peat>bark>milkweed>polypropylene. All four of the filter materials showed a total metal reduction of over 70%, which could be due to the separation of particle-bound metals in the columns. The ageing of the synthetic stormwater showed that dissolved metals, particularly copper, decreased in concentration, quite rapidly. During one experiment run, the dissolved copper concentration was reduced to 15% of its initial value. In order to account for the concentration changes an equation was proposed that normalised the concentration of dissolved metal over the duration of the experiment. During the observation period of 16 months, the zeolite installation removed 52% to 82% and 48% to 94% of total and dissolved copper, respectively. However, the effluent concentrations were still high (360-600 μg/l). There was also an indication of the decreasing filter performance over time with a prediction that the treatment level of total copper would drop to approximately 25% by the end of the service life of three years. The hydraulic experiments on a scaled model of a BGS showed that wider cells were on average 13% more efficient in trapping the particles than the narrower variant. The cell wall angle also had an impact (tilted walls added to the sedimentation efficiency), although the applicability of such cell structures can be questioned, as this cell shape may hinder maintenance efforts. It was also hypothesised that the inclusion of the BGS in the pond reduces the area needed for sediment settling, thus making the pond more area-efficient and easier to include in an urbanised setting. 
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23.
  • Milovanovic, Ivan, 1990-, et al. (författare)
  • Enhancing stormwater sediment settling at detention pond inlets by a bottom grid structure (BGS)
  • 2020
  • Ingår i: Water Science and Technology. - London, UK : IWA Publishing. - 0273-1223 .- 1996-9732. ; 81:2, s. 274-282
  • Tidskriftsartikel (refereegranskat)abstract
    • Stormwater sediments of various sizes and densities are recognised as one of the most important stormwater quality parameters that can be conventionally controlled by settling in detention ponds. The bottom grid structure (BGS) is an innovative concept proposed in this study to enhance removal of stormwater sediments entering ponds and reduce sediment resuspension. This concept was studied in a hydraulic scale model with the objective of elucidating the effects of the BGS geometry on stormwater sediment trapping. Towards this end, the BGS cell size and depth, and the cell cross-wall angle were varied for a range of flow rates, and the sediment trapping efficiency was measured in the model. The main value of the observed sediment trapping efficiencies, in the range from 13 to 55%, was a comparative assessment of various BGS designs. In general, larger cells (footprint 10 × 10 cm) were more effective than the smaller cells (5 × 5 cm), the cell depth exerted small influence on sediment trapping, and the cells with inclined cross-walls proved more effective in sediment trapping than the vertical cross-walls. However, the BGS with inclined cross-walls would be harder to maintain. Future studies should address an optimal cell design and testing in an actual stormwater pond.
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24.
  • Milovanovic, Ivan, 1990-, et al. (författare)
  • Performance of a Zeolite Filter treating Copper Roof Runoff
  • 2022
  • Ingår i: Urban Water Journal. - : Taylor & Francis. - 1573-062X .- 1744-9006. ; 19:5, s. 499-508
  • Tidskriftsartikel (refereegranskat)abstract
    • Copper is a common roofing material used in urban environments, yet it poses a threat to the ecosystem. Space requirements for stormwater treatment in urban areas are often problematic. This study investigated the treatment efficiency of a filter system containing zeolite as filter medium and treatment of copper roof runoff in field conditions. Emphasis was placed on copper and zinc treatment, while the release of sodium and aluminium was also evaluated. The filter system was monitored over a period of 16 months (7 sampling events). The filter reduced the total and dissolved copper by 52–82% and 48–85%, respectively. Although the average observed treatment efficiency of copper and zinc was high, considerable decline in filter efficiency was noticed, indicating potential saturation of the filter medium. Moreover, the copper concentrations in the outlet were still high, 350–600 μg/l, and significantly higher than the concentrations recommended by the relevant authorities.
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25.
  • Milovanovic, Ivan, 1990-, et al. (författare)
  • Synthetic stormwater for laboratory testing of filter materials
  • 2023
  • Ingår i: Environmental technology. - : Taylor & Francis. - 0959-3330 .- 1479-487X. ; 44:11, s. 1600-1612
  • Tidskriftsartikel (refereegranskat)abstract
    • Synthetic stormwater was tested to determine the ageing effects on dissolved metal concentrations and used in a column experiment to determine efficiency of four different filter materials (milkweed, bark, peat, polypropylene) in removing total and dissolved metals. Synthetic stormwater was created by adding metal salts, oil and collected stormwater sediment to tap water. Two ageing experiments were performed to determine the change of synthetic stormwater quality over time. One experiment lasted for 11 days and another focused on rapid concentration changes one day after preparation. The one-day ageing experiment showed rapid decrease in dissolved concentration of certain metals, specifically Cu. To consider this change, correction coefficients for each metal were developed and used to estimate the average dissolved metal concentration in the synthetic stormwater during the experiment to determine filter treatment efficiency. During the 11-day experiment on metal concentrations, no noticeable quality changes were observed for at least six days after the preparation of synthetic stormwater. Furthermore, a column experiment was run with duplicate filter columns. Inflow and outflow samples were analysed for total and dissolved metals, turbidity, particle size distribution, and pH. High removal of total metal concentrations was noticed in all tested filter media (58-94%). Dissolved metal concentration removal varied among different filter media. In general, columns with bark and peat media were able to treat dissolved metals better than polypropylene and milkweed. The level of treatment of dissolved metals between the different filter media columns were bark > peat > milkweed > polypropylene.
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26.
  • Milovanovic, Ivan, 1990-, et al. (författare)
  • Zeolitfilter för avrinning från koppartak
  • 2024
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Koppar används ibland som takmaterial i städer, men det medför problem för miljön. Avrinningen från koppartak är svår att behandla i stadsmiljöer. En ny studie har tittat på hur effektivt ett filtersystem med zeolit som filtermedium kan vara för att minska kopparhalten. Resultaten visar att filtret lyckades minska total och löst koppar med 52–82 % respektive 48–85 %. Trots detta var kopparhalterna i avrinningen fortfarande höga, mellan 350–600 μg/l. Detta överstiger rekommenderade nivåer och indikerar behovet av fortsatt forskning för att förbättra behandlingsmetoderna och minimera miljöpåverkan från koppartak.
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27.
  • Nyström, Fredrik, 1983- (författare)
  • Coagulation process characteristics and pollutant removal from urban runoff
  • 2019
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • 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.
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28.
  • Nyström, Fredrik, 1983- (författare)
  • Kemisk fällning - en möjlig reningsprocess för dagvatten
  • 2023
  • Rapport (populärvet., debatt m.m.)abstract
    • Dagvatten från starkt förorenade ytor, såsom motorvägar och större vägkorsningar, leds ofta till dagvattendammar eller andra dagvattensystem. Reningseffekten hos dessa system har ett samband med deras area eftersom de har sedimentering som främsta reningsprocess. Urbaniserade områden bebyggs i dag allt tätare och de tillgängliga ytorna för dagvattenhantering är begränsade. Samtidigt blir miljökraven mer stringenta. Då kan det vara svårt att anlägga system som är dimensionerade för att avskilja föroreningarna tillräckligt effektivt. Flera studier har därför fokuserat på hur effekten hos befintliga system kan förstärkas. I rapporten beskrivs hur väl en reningsprocess med kemisk fällning fungerar på förorenat dagvatten.Kemisk fällning är en välkänd process i vattenverk och avloppsreningsverk där den används för att den är mycket effektiv när det gäller att avskilja både partiklar och fosfor. Många föroreningar i dagvatten förekommer i hög grad som partiklar eller är bundna till partiklar. Därför borde en process med kemisk fällning kunna åstadkomma hög avskiljning även för dagvatten. Men det har inte gjorts särskilt många studier på ämnet, och det har inte genomförts någon bredare undersökning av hur processen fungerar för dagvattenrening. Syftet med projektet var därför att undersöka vilka fällningskemikalier som lämpar sig för dagvatten, vad som bör beaktas i en sådan process och hur bra processen kan bli på att avskilja typiska dagvattenföroreningar. Insamlat dagvatten testades under kontrollerade förhållanden på laboratorium. För att utvärdera processen användes dels en snösmältblandning från en plogbank i Luleå, dels vägdagvatten. Det viktigaste resultatet var att reningsgraden blev mycket hög, över 90 procent, för merparten av metallföroreningar och organiska föroreningar. Reningsgraden hade även låg variation, motsvarande cirka en till fem procentenheter. De fällningskemikalier som presterade bäst var kommersiella förhydrolyserade fällningsprodukter. För att erhålla en kemisk fällning är parametrarna pH och alkalinitet viktiga, och vissa dagvatten kan behöva en pH-justering. Kemisk fällning hade även en tydlig effekt på avskiljning av mindre partiklar (<1μm). Vid enbart sedimentering avskildes inte den fraktionen utan hölls i suspension.Resultaten ska bidra till kunskap om kemisk fällning av dagvatten som kan ge verksamhetsutövare en bredare verktygslåda för effektiv dagvattenrening.
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29.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Laboratory scale evaluation of coagulants for treatment of stormwater
  • 2020
  • Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 36
  • Tidskriftsartikel (refereegranskat)abstract
    • The treatment effect and process characteristics of coagulation were investigated in semi-synthetic stormwater in laboratory-scale using jar tests. An initial screening of twelve coagulants and flocculant aids was carried out to find a selection of chemicals that efficiently reduced turbidity and suspended solids. Five coagulants were then further investigated with additional parameters measured (conductivity, alkalinity, and ζ-potential). The semi-synthetic stormwater was characterized by a high but variable, particle content, and low alkalinity. In the jar tests, a high treatment efficiency (>90 % reduction of both turbidity and suspended solids) was achieved for all coagulants. For very low alkalinity waters, the use of a biopolymer such as chitosan may be advantageous due to minimal alkalinity consumption. Based on the occurrence of charge reversal for all chemicals investigated, the mechanism for coagulation was likely charge neutralization. Treatment effect occurred in the ζ-potential span of -14 to +1 mV depending on the coagulant used. Initial turbidity and the ζ-potential are interesting parameter candidates for dosing control in stormwater treatment applications.
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30.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Polymer-assisted hydraulic dredging for quality control of stormwater pond sediment and reject water – Influence of polymer choice and its preparation
  • 2023
  • Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 51
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydraulic dredging of stormwater ponds may include on-site dewatering of dredged materials using polymersand geotextile filtration. The choice of polymer and its preparation affect the overall operational effectivenessand the quality of the reject water (filtrate) returned to the stormwater pond. This study examined the resultingparticle content as well as nutrient and metal concentrations in the filtrate conducted on hydraulically dredgedstormwater sediment that was chemically conditioned and filtered through geotextile. This study investigateshow polymer choice and preparation affects the outcome. In total, three types of polymers were tested (powder,emulsion commercial cationic polymers and chitosan), the water (tap water or reclaimed) the polymer wasprepared in, and the aging time of the polymer solution. Deviations from manufacturer's instructions on thepolymer preparation increased the amount of polymer needed for an optimal conditioning process. In terms ofpollutant retention, there was no difference between polymer preparations. In the filter cake there was nodiscernable difference between conditioned and unconditioned sediment, rather the difference was noticeable onthe filtrate. Conditioned stormwater sediment produced a geotextile filtrate with considerably less metal andnutrient content than the unconditioned stormwater sediment.
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31.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Removal of metals and hydrocarbons from stormwater using coagulation and flocculation
  • 2020
  • Ingår i: Water Research. - : Elsevier. - 0043-1354 .- 1879-2448. ; 182
  • Tidskriftsartikel (refereegranskat)abstract
    • As the understanding of how stormwater pollutants are fractioned and need for mitigation has increased, so has the investigation into more advanced treatment techniques. The present study investigated the treatment efficiency of coagulation/flocculation and sedimentation in semi-synthetic stormwater. Five coagulants were evaluated in terms of reducing particle content, organic carbon, total and dissolved metals, hydrocarbon oil index, and polycyclic aromatic hydrocarbons (PAHs). Changes in the resulting particle size distribution as a consequence of the coagulation treatment were also investigated. The pollutants in the semi-synthetic stormwater were predominantly in the particulate phase. The medium and longer chained hydrocarbons dominated the hydrocarbon oil index, while medium to high molecular weight PAHs were most abundant. Iron chloride was the only coagulant that affected particle size distribution post-treatment, shifting the distribution toward larger particles. In terms of total metal removal, the performance of the coagulants was similar, with over 90% removal on average. Concentration of zdissolved copper, one of the metals found in the dissolved phase, was reduced by 40% via coagulation treatment. The iron chloride coagulant increased dissolved Zn, a change attributed to a considerable drop in pH resulting in higher ion mobility. Similarly, the reduction in organic content (total organic carbon, oil, and PAHs) was over 90% for most coagulants.
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32.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Removal of metals and hydrocarbons from urban snowmelt by coagulation and flocculation
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • 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.
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33.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Removal of small particles from urban snow melt mixture by coagulation/flocculation and sedimentation
  • 2017
  • Ingår i: 14th IWA/IAHR International Conference on Urban Drainage.
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • 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.
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34.
  • Nyström, Fredrik, 1983-, et al. (författare)
  • Treatment of road runoff by coagulation/flocculation and sedimentation
  • 2019
  • Ingår i: Water Science and Technology. - : IWA Publishing. - 0273-1223 .- 1996-9732. ; 79:3, s. 518-525
  • Tidskriftsartikel (refereegranskat)abstract
    • 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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35.
  • Sami, Mashreki, et al. (författare)
  • Greywater treatment in a green wall using different filter materials and hydraulic loading rates
  • 2023
  • Ingår i: Journal of Environmental Management. - : Elsevier. - 0301-4797 .- 1095-8630. ; 340
  • Tidskriftsartikel (refereegranskat)abstract
    • Green walls in urban environments can be both an aesthetic feature and be of practical use in greywater treatment. This study evaluates the effect of different loading rates (4.5 l/d, 9 l/d, and 18 l/d) on the efficiency of treating actual greywater from a city district in a pilot-scale green wall with five different filter materials as substrates (biochar, pumice, hemp fiber, spent coffee grounds (SCG), and composted fiber soil (CFS)). Three cool climate plant species, Carex nigra, Juncus compressus, and Myosotis scorpioides, were chosen for the green wall. The following parameters were evaluated: biological oxygen demand (BOD), fractions of organic carbon, nutrients, indicator bacteria, surfactants, and salt. Three of the five materials investigated – biochar, pumice, and CFS - showed promising treatment efficiencies. The respective overall reduction efficiencies of BOD, total nitrogen (TN) and total phosphorus (TP) were 99%, 75%, and 57% for biochar; 96%, 58%, and 61% for pumice; and 99%, 82% and 85% for CFS. BOD was stable in the biochar filter material with effluent concentrations of 2 mg/l across all investigated loading rates. However, higher loading rates had a significantly negative effect on hemp and pumice for BOD. Interestingly, the highest loading rate (18 l/d) flowing over pumice removed the highest levels of TN (80%) and TP (86%). Biochar was the most effective material in removing indicator bacteria, with a 2.2–4.0 Log10 reduction for E. coli and enterococci. SCG was the least efficient material, giving a higher BOD in the effluent than in the influent. Therefore, this study presents the potential of natural and waste-derived filter materials to treat greywater effectively and the results can contribute to the future development of nature-based greywater treatment and management practices in urban areas.
  •  
36.
  • Sami, Mashreki, et al. (författare)
  • On-site greywater treatment systems - influent and effluent quality
  • 2023
  • Annan publikationabstract
    • The dataset presented here consists of raw data on the quality of influent and effluent greywater from eight on-site greywater treatment systems situated in Södertälje municipality, Sweden. These on-site treatment systems included three types of commercially available package plants and one sand filter. The influent and effluent samples were taken as grab samples between August 2020 and December 2021 and analysed for organic material, nutrients, pathogens, anionic surfactants, salt and (for two of the eight on-site systems) microplastics. Supporting parameters, e.g. suspended solids and pH, are also included. Further, for microplastics, results from blank samples are included.This dataset was used to evaluate the treatment efficiency of the on-site greywater treatment systems and to assess the suitability of the treated water for reuse.
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37.
  • Sami, Mashreki (författare)
  • Performance of on-site systems and a green wall for greywater treatment
  • 2023
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Greywater contains inorganic and organic substances, nutrients, pathogens, micropollutants and microplastics. Source-separated greywater using decentralized systems can potentially provide energy-efficient and low-maintenance treatment. If effectively treated, greywater could be a source for non-potable water use in for instance urban landscaping or agricultural irrigation. The overall aim of this thesis was to investigate the treatment efficiencies of two different types of decentralized greywater treatment systems: a) on-site package plants and b) a nature-based solution (NBS) - green wall. These two different treatment systems were assessed based on their removal efficiency of organic matter (BOD, COD, TOC), nutrients (nitrogen (N) and phosphorus (P)), surfactants, indicator bacteria (E. coli and enterococci) as well as microplastics.The study of the on-site package plants investigated eight on-site greywater treatment facilities of four different types (A, B, C and D). Systems types A-C were commercially available and type D was an onsite built sand filter. The treatment unit of type A consisted of a trickling filter fitted with geotextile resting on a sand filter bed. The treatment unit of type B included a fibrous mineral wool filter material while type C contained a series of fine-meshed plastic filters. Prior to types A, B and D, septic tanks were located to contribute with pre-treatment, whereas type C, the smallest system investigated, included a septic tank within the treatment unit. >90% removal of organic matter (BOD and COD) was achieved by types A and D, but the N removal was comparatively higher by type B (44-68%). Effective P removal was only observed in type D (56%). However, the effluent concentration from all the systems was <3mg/l. The treatment efficiency of type C was found to be relatively low.In the green wall study, the efficiency of five filter materials (pumice, biochar, hemp fiber, spent coffee ground (SCG) and compost fiber soil) were evaluated with regards to hydraulic loading rates (HLRs) (4.5, 9, and 18 l/d). The treatment efficiency varied significantly with materials and HLRs. Biochar consistently removed 99% of BOD for all HLRs. High N removal (>80%) was observed by pumice and biochar during the high HLR (18 l/d). However, P removal by hemp was comparatively higher (75-85%) than by biochar and pumice. SCG and compost soil was tested with only 4.5 l/d, where compost soil showed effective treatment of BOD (99%), N (82%) and P (85%). SCG was the least effective material releasing more organics and nutrients in the effluent. Both the studies showed high concentration (>105 cfu/100 ml) of E. coli and enterococci in the influent and effluent greywater. The treatment systems were in general not effective in removing E.coli and enterococci. The most efficient system was the sand filter (D), achieving 1.4-3.8 log10  E.coli reduction and 2.3-3.3 log10 reduction for enterococci. Biochar achieved similar removal at HRL 4.5 l/d. Using thermal extraction desorption gas chromatography-mass spectrometry (TED-GCMS) technique, polyvinylchloride, polystyrene, poly-ethylene-terephthalate, polyethylene, polypropylene, and polyamide 6 were detected in the influent and effluent greywater in both studies. Even though there was variability in the influent concentrations, low concentrations were observed in the effluents, suggesting the systems were effective in retaining the microplastics.
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38.
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39.
  • Sami, Mashreki, et al. (författare)
  • Quality of greywater from a city district before and after treatment in a green wall
  • 2023
  • Annan publikationabstract
    • The dataset presented here consists of raw data on the quality of influent greywater generated from a city district with 800 PE (population equivalent) and the effluent quality of greywater after treatment using a green wall. Five natural filter materials (pumice, biochar, hemp fiber, spent coffee ground, and composted fiber soil) were used in the green wall and tested for three hydraulic loading rates (54, 108 and 216 l/m2/d). The influent and effluent samples were taken manually between November 2021 and March 2022 and were analyzed for organic material, nutrients, pathogens, anionic surfactants, salt and microplastics. Supporting parameters e.g. suspended solids and pH, are also included in the dataset. Further, for microplastics, results from blank samples are included. This dataset was used to evaluate the treatment efficiency of the filter materials at different hydraulic loading rates.
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40.
  • Sami, Mashreki, et al. (författare)
  • Removal of Microplastics from Greywater Using a Green Wall Treatment System
  • 2022
  • Ingår i: 17th International Conference on Wetland Systems for Water Pollution Control: Conference Proceedings. ; , s. 505-508
  • Konferensbidrag (refereegranskat)abstract
    • A green wall with four filter media - pumice, biochar, hemp, and compost soil - was investigated with regard to the removal of microplastics from real greywater. Nine polymers were analysed using thermal extraction desorption gas chromatography-mass spectrometry (TED-GC/MS). The results showed the presence of polyvinylchloride (PVC), polystyrene (PS), poly-ethylene-terephthalate (PET), polypropylene (PP), and polyamide (PA) in the influents and effluents. High concentration of PS (22 μg/l) and PET (73 μg/l) were observed in the influent but were removed efficiently in the green wall with effluent concentrations of <2 μg/l from all filter materials except for hemp. The effluent from one hemp replicate showed higher concentrations of PVC (58 μg/l) and PET (114 μg/l) than the influent. During the sampling period, all filter materials removed TSS, BOD and TOC by >90%.
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41.
  • Söderholm, Kristina, 1973-, et al. (författare)
  • Flexible and Resource-Recovery Sanitation Solutions: What Hindered Their Implementation? A 40-Year Swedish Perspective
  • 2023
  • Ingår i: The Journal of urban technology. - : Taylor & Francis. - 1063-0732 .- 1466-1853. ; 30:1, s. 23-45
  • Tidskriftsartikel (refereegranskat)abstract
    • Although Sweden pioneered in the development of resource-recovery sanitation solutions, and there has existed a political awareness of such solutions since the 1990s, their implementation has been slow. We adopt a historical (40-year) perspective and use the main journal of the Swedish sanitation sector as source material to go into depth why this has been the case. Central explanations emerge in terms of previously strong governmental control and continuously tightened environmental requirements that ceaselessly have expanded and strengthened the large-scale centralized sanitation system. In parallel, the sector has continuously been reminded of the shortcomings of alternative (and smaller) solutions and of the tension between recovery and treatment/risk management. The study highlights the possibility of achieving long-term and profound impacts from policy mixes, as well as the strong influence of the sum of challenges and choices over a long time, on today’s perspectives and propensity for change.
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42.
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43.
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44.
  • Vidal, Brenda, 1987-, et al. (författare)
  • Assessing the sustainability of on-site sanitation systems using multi-criteria analysis
  • 2019
  • Ingår i: Environmental Science. - Cambridge : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 5:9, s. 1599-1615
  • Tidskriftsartikel (refereegranskat)abstract
    • Small on-site sanitation systems are widely present in suburban and rural areas in many countries. As these systems often underperform and have an impact on receiving waters, understanding their overall sustainability is of interest for policy and decision-makers. However, the definition and estimation of indicators defining sustainability are challenging, as it is finding the methodological approach to combine qualitative and quantitative indicators into one comprehensive assessment. In this study, twelve indicators defined by environmental, economic, social, technical and health-related criteria were used to compare nine alternatives of on-site sanitation for single households. A non-compensatory method for multi-criteria decision analysis, ELECTRE III, was used for the assessment together with weights assigned to each indicator by a reference group. Several scenarios were developed to reflect different goals and a sensitivity analysis was conducted. Overall, the graywater-blackwater separation system resulted as the most sustainable option and, in terms of polishing steps for phosphorus removal, chemical treatment was preferred over the phosphorus filter, both options being implemented together with sand filters. Assessing the robustness of the systems was a crucial step in the analysis given the high importance assigned to the aforementioned indicator by the stakeholders, thus the assessment method must be justified. The proposed multi-criteria approach contributes to aid the assessment of complex information needed in the selection of sustainable sanitation systems and in the provision of informed preferences. © 2019 The Royal Society of Chemistry.
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45.
  • Vidal, Brenda, 1987- (författare)
  • On-site sanitation systems - An integrated assessment of treatment efficiency and sustainability
  • 2018
  • Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Small on-site sanitation systems for wastewater collection and treatment are prevalent in suburban and rural areas in many countries. However, these systems often underperform, causing potential impact to the receiving waters and increasing the risks to public health, thus hindering the overall sustainability of the systems. Understanding the different sustainability dimensions and trade-offs between assessment indicators can support the planning of sustainable on-site sanitation systems for a specific context. The overall aim of this thesis was to evaluate the sustainability and function of on-site sanitation systems by defining a set of indicators to assess on-site sanitation options and estimating them for different scenarios, and by investigating the treatment efficiency of on-site facilities for domestic wastewater treatment in a field study. Particular attention was given to the removal of phosphorus (P) and indicator bacteria due to their relevance in terms of eutrophication risk and public-health concern.In a multi-criteria approach, twelve indicators were defined to assess nine on-site sanitation systems. A reference group representing stakeholders’ views assigned weights to express the relative importance of each indicator. The reference group assigned the highest weights to the indicators robustness, risk of pathogen discharge and nutrient removal. Assessing the robustness proved to be challenging, as there is a gap between how the sanitation systems are expected to perform based on their design, and how they actually perform in practice, mainly due to incorrect construction, operation and maintenance. The discriminating power of the indicators was calculated using the entropy method, which showed that the indicators energy recovery and capital cost had little impact in the final ranking of the alternatives. A sustainability ranking was obtained by using the method ELECTRE III. A scenario analysis based on different settings of interest based on socio-economic and geographical factors was done to evaluate the changes in the ranking of alternatives. Overall, the greywater–blackwater separation system ranked the highest in the baseline scenario and when nutrient-related indicators were important (Scenario 2), together with the urine diversion system. The sand filter and drain field were the most sustainable options when nutrient removal and recycling was not important (Scenario 1), and (in combination with chemical P-removal) when the indicators related to energy and climate change had the highest weights (Scenario 3). In terms of P-removal, chemical removal outranked the alkaline P-filter.In a field study, the effluent wastewater from twelve on-site wastewater treatment facilities with sand and alkaline P-filters was evaluated in terms of removal and discharge of organic content, total and dissolved phosphorus, and indicator bacteria (E. coli, total coliforms, intestinal enterococci and C.perfringens). The results showed that the investigated sand filters generally had low P-removal capacity and sometimes exceeded the criteria for excellent water quality set by the EU bathing water directive with regard to intestinal enterococci and E. coli. Only one sand filter of eight was confirmed to remove P according to the Swedish guidelines for areas with non-sensitive receiving waters with a tot-P effluent concentration below 3 mg L−1. This indicates that a downstream treatment step is needed to meet the guidelines regarding P discharge concentrations. Alkaline P-filters generally removed P efficiently. Despite high effluent pH, the collected data did not generally confirm a further reduction of the bacterial content of the wastewater in the P-filters, as had been previously hypothesized. However, effluent concentrations of indicator bacteria showed moderate positive correlations with effluent concentrations of P and organic matter, indicating the potential of the P-filters to serve as a polishing step also for bacteria.
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46.
  • Vidal, Brenda, 1987-, et al. (författare)
  • Phosphorus reduction in filters for on-site wastewater treatment
  • 2018
  • Ingår i: Journal of Water Process Engineering. - : Elsevier. - 2214-7144. ; 22, s. 210-217
  • Tidskriftsartikel (refereegranskat)abstract
    • Discharges of phosphorus (P) from on-site wastewater treatment systems generally contribute to eutrophication problems in Swedish freshwaters and, ultimately, in the Baltic Sea. Such concerns have led to a growing interest in improving P removal in treatment facilities. This study investigated the reduction of P in 12 full-scale on-site treatment systems featuring sand filters and alkaline P-filters by sampling and analysing filter influents and effluents. The flow-proportional samples collected were analysed for total and dissolved P, BOD7, total and dissolved organic carbon (TOC and DOC), and pH. Seven of the eight investigated sand filters did not provide satisfactory total P reduction; the likely explanations are filter clogging and wastewater dilution by extraneous water. In addition, effluents from four of the eight sand filters had total P concentrations higher than 3 mg L−1, which is the Swedish effluent limit recommended for common receiving waters, indicating that a subsequent polishing step would be needed. Six of the nine investigated P-filters reduced P adequately, with total P concentrations in the effluent ranging between 0.1 and 1.9 mg L−1. The three underperforming P-filters had effluent pH values below 9; filter age, clogging, and hydraulic overload were identified as probable reasons for their poor performance. A statistically significant correlation was found between total-P reduction and filtrate pH, but no significant correlation was detected between organic load in the influent and P reduction by the P-filters. The P-filter media replacement frequency could not be established, but filtrate pH appeared to be a good estimator.
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47.
  • Vidal, Brenda, 1987- (författare)
  • Small Sanitation Systems – Treatment Efficiency, Sustainability and Implementation
  • 2022
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Current socio-technical wastewater system paradigms are being challenged by emerging global issues such as climate change, environmental degradation and scarcity of resources. Thus, exploration of innovative new urban water management solutions is required that enable closure of resource loops. On-site and decentralised wastewater systems are seen as emerging solutions, partly because of their flexibility, as they increase the potential for recovery and reuse of resources like nutrients. At the smallest scale, on-site wastewater treatment systems are widely present in rural and peri-urban areas globally. However, they often do not meet acceptable levels of nutrient and bacterial discharge, thereby contributing to environmental degradation and health risks. The overall aim of this doctoral dissertation is to improve knowledge and understanding of small sanitation systems in terms of treatment processes and efficiency, their sustainability and implementation. At a greater scale, the dissertation explores the historical and current contexts that have shaped, and are shaping, the existing wastewater sector, dominated by large-scale centralised mixed wastewater collection and treatment, and barriers to implementation of alternative, innovative sanitation solutions with higher resource recovery capacities, like source separating systems.Sixteen full scale on-site facilities for wastewater treatment in Sweden were investigated in the research the thesis is based upon, including sand filters and package plants. Sand filters followed by alkaline phosphorus filters showed good removals of organic matter and high P-removal capacity (>92%). Six (of 11) investigated package plants showed >78% phosphorus removal (including chemical precipitation and alkaline phosphorus filters as treatment steps). Nitrogen removal was generally low in the package plants, likely because of the low average temperatures, and appeared to be mainly mediated by sedimentation of particulate organic nitrogen. Denitrification was observed to a limited extent in facilities with effective water/sludge recirculation. High densities of indicator bacteria were found in the effluent of most facilities as the removal rates were low, often exceeding the EU Bathing Water Directive’s limits for excellent water quality in terms of intestinal enterococci and Escherichia coli. Levels of pharmaceuticals detected in the effluent of package plants were within the range or higher than previously reported in effluents from conventional wastewater treatment plants, and included anti-inflammatories, β-blockers, ACE inhibitors, anticonvulsants and antidepressants. Effluent concentrations of phthalates were below those previously reported in the literature.A scenario analysis comparing nine on-site sanitation options suggested that source separation of greywater and blackwater and urine diversion were the most sustainable options when nutrient removal and recycling were highly prioritised. A conventional sand filter or drain field were the most sustainable options when nutrient removal and recycling were less prioritised and, (in combination with chemical P-removal) when CO2 emissions and energy use and recovery were important aspects.When planning wastewater services for a given area, results of interviews with water professionals confirmed the general trend to opt for a centralising approach, whenever technically feasible, by installing pumping stations and connecting sewer pipes to a main treatment plant, in contrast to building decentralised systems. Reasons mentioned by the interviewees included the robustness of the system, simplicity of operation and maintenance and protection of the receiving waters. Identified barriers hindering implementation of alternative sanitation solutions with focus on resources recovery included factors categorized as legislative factors (lack of requirements and law interpretation), technical factors (immature technologies, uncertainties), organizational factors (lack of initiative, competence and experience) and economic factors (financial limitation, lack of incentives). From a historical perspective, strong governmental control and continuous enforcement of environmental requirements drove the expansion and strengthened the domination of the large-scale centralised sanitation system. Alternative sanitation systems with higher resource recovery capacities have received less attention and institutional support, and their shortcomings were constantly highlighted during the period covered by a historical review (1974-2015).
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48.
  • Vidal, Brenda, 1987-, et al. (författare)
  • Små avloppssystem – hur hållbara är de?
  • 2019
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Små avloppssystem släpper ut avloppsvattnet lokalt, och därför är det viktigt att systemen uppfyller de krav som finns för utsläpp av organiskt material och näringsämnen och även klarar krav på smittskydd. Ofta fungerar, tyvärr, de små systemen inte som de borde, och när anläggningar ska uppgraderas eller när det ska byggas nya system bör det ske med tanke på hållbarheten. I ett nyligen avslutat projekt har vi arbetat med små avloppssystem i relation till hållbarhetskriterier och olika scenarier. Studien visar att det är viktigt att sätta upp mål och prioriteringar när man ska välja avloppslösning. Vilket som är det mest hållbara alternativet beror på vilka aspekter som prioriteras.
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49.
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50.
  • Vidal, Brenda, 1987-, et al. (författare)
  • Utvärdering av drifts- och underhållsinstruktioner för markbaserade avloppsprodukter : En analys av nuvarande praxis och möjliga förändringar
  • 2023
  • Rapport (övrigt vetenskapligt/konstnärligt)abstract
    • Alla avloppslösningar kräver skötsel och underhåll för att fungera ändamålsenligt under hela sin livslängd. Underhållsbehovet varierar beroende på storlek, typ och reningsgrad. I Havs- och vattenmyndighetens vägledning om prövning av små avlopp finns ett avsnitt om drift- och underhållsinstruktion samt ett översiktligt informationsblad. Redan i tillståndsansökan bör sökanden redovisa anläggningens behov av underhåll, kontroll och service i en så kallad drift- och underhållsinstruktion. Instruktionen bör innehålla både den egenkontroll som verksamhetsutövaren själv avser utföra och den eventuella kontroll som behöver utföras av sakkunnig. Instruktionen måste sammanfattningsvis innehålla nödvändiga uppgifter för att säkerställa anläggningens funktion i drift.Tidigare studier om uppföljande besök på prefabricerade markbädd visade att det finns brist på tydliga skötselinstruktioner till fastighetsägaren och brist på insikt om skötselansvar hos fastighetsägarna. Syftet med detta projekt var att undersöka i vilken utsträckning det finns drifts- och underhållsinstruktioner som motsvarar HaV:s nuvarande vägledning för markbaserade avloppsprodukter på marknaden, samt att i dialog med branschen utvärdera om det finns anledning att göra förändring i vägledning, i drift- och underhållsinstruktioner för markbaserade avloppsprodukter på marknaden och/eller i fysisk utformning av anläggningarna.
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