The river  Österdalälven  deposits  large  amounts  of sediment  when it  passes through  the city of Mora. The sediment  deposition  risks  clogging  the inlet  to the lake  Siljan,  hampers navigation,  and creates a risk  of the river  forming  new channels.  This study  has addressed the problem  by creating  a numerical  2D depth-averaged combined hydrodynamic  and sediment  transport  model  of the reach. The study focused on the mechanisms  behind  the sedimentation  and erosion  patterns. River  training  structures in  the form of groynes  were added to the model  to investigate  whether  mitigation  of the problem  by physical  structures was possible.  Because  of the lack  of field  data, some of the flow  and sediment  transport parameters  had to be estimated. Sensitivity  analyses were performed to analyse the model’s response to the choice  of boundary  conditions,  input parameters, and auxiliary  models. The study concluded that erosion  occurs in areas where  the shear stress or flow  velocity  is  high  and sedimentation  in  areas with flow circulation and lower flow  velocity.  The sediment yield at the problem  area, i.e. at the mouth in Siljan  was flow-dependent  and increased  with  larger  flow discharges. The yearly  sediment  yield was low  compared  to stations  downstream. The model  was sensitive  to the choice of boundary conditions,  Manning’s roughness  coefficient,  and sediment  transport  mode and transport  capacity  formula.  The main  conclusion was that it  is  crucial  to collect  the relevant  field  data to obtain more reliable  result  for further  studies. It was further concluded  that physical  structures  in  the form of groynes  could  decrease the amount  of sediment  that deposits at the mouth of Österdalälven in  Siljan. The study has shown that it  is  possible  to create a working  numerical  river  model  based on the physical  understanding  of the flow  despite  the lack of field  data.

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.

Disease related to unsafe water, poor sanitation, and lack of hygiene is some of the most common causes of illness and death all around the world. Since the first detection of Legionella in Philadelphia 1976, Legionella is recognized to cause Legionellosis which is associated with two distinct forms: Legionnaires’ disease and Pontiac fever. The fact that vaccination against Legionella disease is not efficacious enhances the effort towards developing the existence disinfection methods and inventing new technologies. Re-colonization of Legionella in hot water systems may occur within a few days or weeks after disinfection since conventional disinfection methods significantly reduce but do not eliminate pathogens. Understanding the conditions favoring Legionella occurrence in hot and cold systems will aid in developing new treatment technologies that minimize or eliminate human exposure to legionella pathogens. The work introduces the Anti-Bact Heat Exchanger (ABHE) system as a new innovative system inspired by nature. Compared to conventional disinfection methods, the ABHE system proposed to achieve continuous thermal disinfection of bacteria in hot water systems and in simultaneously saving energy and reducing the required costs. Thermodynamic analysis, experimental test and simulation validation of the ABHE by the Engineering Equation Solver (EES)-based model were achieved to define the thermal performance of the ABHE system at given operation conditions. The experimental test shows high potential of recovering heat and thus saving energy by the ABHE system. In addition, pumping power (PP) was relatively small compared to the recovered heat which implies that less energy was required compared to the recovered heat. The effect of working parameters such as temperatures and flow rate on the thermal performance of the ABHE system was furthermore investigated. The study shows that supplied water temperature has similar effects as the disinfection temperature. Namely, increasing supplied water temperature enhances the regeneration ratio (RR) but it requires a large plate heat exchanger (PHE) area and PP. On the contrary, increasing the temperature in use results in a reduced PHE area and PP. Flow rate has the greatest influence on the thermal performance of the ABHE system. Increasing flow rate leads to an increase in the required area of the PHE. The EES-based model investigated the effect of the length and the width of the plates used in the PHE on the RR and the required area of the PHE. Then, the EES-based model was used to optimize the ABHE system in which the PHE area is minimized or the RR of the ABHE system is maximized.

The global energy consumption, which increased ~84% during last thirty years, exceeded 1.4.1011 MWh in 2008. It is projected to increase another ~39% until 2030. Current energy trends are unsustainable. Considering that 30-50 % of the global energy consumption is consumed for heating and cooling, more efficient heating and cooling systems are needed. The current power situation in Syria is serious and is likely to speed up the implementation of renewable energy systems. Comparison between the conventional fuel heater, electrical heater, air source heat pump and ground source heat pump in Syrian climate shows that GSHP systems have big potential and can make huge contributions to overcome the current energy shortage in Syria. Since the heating demand in Syria is almost twice the cooling demand, it is possible to use such systems for free cooling. Therefore, heat recharge of the borehole field is important. The amount of available solar energy in Syria, means that the combination of solar and GSHP has great potential. Climatic and geological conditions were analyzed for GSHP systems in Syria, which was chosen as a case study for the Middle East. A general study was made on the need for large-scale utilization of renewable energy, including an overview of different energy storage systems for heating and cooling. Chicken farms were chosen as a study case since the poultry industry is an important sector in Syria. There are 13,000 chicken farms with an annual production of 172,000 tons of meat. It employs almost 150,000 people and has a large heating and cooling demand (1.34 TWh/year).Next step was the design and simulate the operation of a GSHP system for a typical chicken farm in Syria. Based on this study the national potential for such systems was estimated. GSHP systems at all Syrian chicken farms would annually save 114,000 m3 of oil. Since GSHPs use the ground as a source or sink of thermal energy, the ground temperature is most important for its operation and efficiency. The ongoing global warming, which means that air, ground, and water is getting warmer, has therefore some consequences on such systems. Firstly, the effect of global warming on the ground temperature was studied. An equation, which describes the change of ground temperature field as a function of depth, time, and ground thermal properties, and local (global) warming, was derived. Secondly, the effect of the warming on heating and cooling demand of a certain building was studied in combination with its affects on the efficiency of GSHP system.The proper design of BHE requires knowledge of ground thermal properties, i.e. effective ground thermal conductivity, thermal resistance, and undisturbed ground temperature. Such site specific data were determined by thermal response test for heating and cooling of the Kharseh chicken farm in Hama, Syria. Used thermal response test equipment was designed and constructed within the project. Borehole thermal resistance has considerable effect on the performance of borehole heat exchangers. Therefore, forced convection in a water filled borehole (i.e. non-grouted) was tested to improve the heat transfer. Injected air, at the bottom of a borehole, resulted in a 28% reduction of thermal resistance. Since injected air bubbles caused convection also in the groundwater, surrounding the borehole, the effective thermal conductivity was increased 28%. Future work aims at the construction, operation, and monitoring of suggested GSHP system at the Kharseh chicken farm in Syria. The idea is to demonstrate the GSHP system as a means of promoting and implementing such systems in the Middle East. The main problem now is to get required permissions to build the ground heat exchangers since there is no existing permit procedure for such systems.

Urban runoff often contains high concentrations of particles. Pollutants that adsorbs to surfaces of particulate material will be transported to receiving waters or a sewage treatment plant. For the recipient, the particles in the runoff are a significant cause of water quality impairment. The particles are associated with impacts of surface waters such as increased turbidity, and effects on water-living organisms and fish. The particle concentration is one of the most common parameters to measure in urban runoff.The main objective was to investigate and compare the accuracy of analysis methods for measuring total particle concentration in urban runoff. The methods to be compared are total suspended solids (TSS), suspended sediment concentration (SSC-A, SSC-B and SSC-C), and one new method; multiple filter method (MFM). General differences between the analysis methods:Handling of sample: * SSC and MFM – analysis of entire sample * TSS –aliquot analysisFilter pore size: * TSS and SSC – 1.6 μm * MFM – 0.45 μmThe studies were performed with artificial and natural runoff samples. Three studies with artificial samples were performed a) high amount of small particles, b) high amount of large particles and c) different particle intervals. The study with natural runoff samples, were performed with rainfall runoff, undisturbed snow and snowmelt runoff. The result for artificial samples showed that SSC and MFM gave comparable result irrespective of particle concentration or size, approximately 100 % of the initial concentration. TSS which measures the suspended solids underestimates the particle concentration with 55-90 %. Measured concentrations for samples with particles larger than 0.063 mm were underestimated. The underestimation increased with increased particle size.For rainfall runoff samples a statistical analysis, ANOVA test, showed that MFM gave a significantly higher result than SSC-B and TSS at a confidence level of 95 %. These result implied that small particles of size 0.45 – 1.6 μm influence the results. The ANOVA test showed no significant difference between SSC-B and TSS. The results from this study show that the particle size distribution has importance for the result and the particle concentrations showed to have no influence. / Dagvatten är en bidragande orsak till försämringen av vattenkvaliteten i sjöar och vattendrag bland annat eftersom dessa ökar grumligheten i recipienten vilket påverkar växter, vattenlevande organismer och djur. Partiklar i dagvatten är dessutom av intresse eftersom en stor del av föroreningarna sitter adsorberade på partiklarna, vilka transporterar föroreningarna till recipienter. En av de mest analyserade parametrarna vid karaktärisering av dagvatten är suspenderade partiklar. Syftet med denna uppsats var att studera och jämföra metoder för analys av koncentrationen partiklar i dagvatten. Metoderna är Suspenderade ämnen (TSS), Sediment koncentration (SSC-A, SSB-B och SSC-C) och en ny metod Multi filter metod (MFM) som är under utveckling. Generella skillnader mellan metoderna:Provhantering: * SSC and MFM –analys hela prov * TSS – analys delprovPorstorlek filter: * TSS and SSC – 1,6 μm * MFM – 0,45 μm Försök har utförts med artificiella och naturliga dagvattenprov. För det artificiella dagvattnet utfördes tre försök a) stor andel små partiklar, b) stor andel stora partiklar och c) olika partikelintervall. Försöken på naturliga dagvatten utfördes på dagvatten från regn och snösmältning. Resultaten från prov med artificiellt dagvatten visade att metoderna SSC och MFM ger jämförbara resultat, oberoende av koncentration eller partikelfördelning var resultatet cirka 100 % av invägd mängd. TSS som mäter suspenderade ämnen och där ett delprov tas ut vid analys, underskattade den invägda partikelkoncentrationen med 55-90 %. För prov med partiklar större än 0,063 mm underskattades uppmätt koncentration, underskattningen ökade medökad partikelstorlek.För dagvatten från regn visade en statistisk analys ANOVA test att metoden MFM ger ett signifikant högre resultat (95 %) jämfört med SSC-B och TSS. ANOVA testet visade ingen signifikant skillnad mellan metoderna SSC-B och TSS. Detta tyder på att små partiklar i intervallet 0,45-1,6 μm påverkar resultatet. Resultatet visar att partikelstorleksfördelningen har betydelse för analysresultatet, däremot påverkar koncentrationen inte resultatet.

Stormwater quality monitoring and control is a prerequisite for sustainable water resources management in urban areas. Stormwater monitoring programs are based on general water sampling guidance and, in the absence of standard procedures, employ various sampling and analytical methods. The aim of this thesis is to assess stormwater sampling methods and sample analyses with respect to the bias which may be introduced at different stages of the process of monitoring suspended solids and indicator bacteria.The focus was on the bias introduced by automated sampling methods and by analyses of suspended solids. Towards this end, suspended solids and four indicator bacteria (total coliforms, E. coli, int. enterococci and C. perfringens) concentrations were compared in stormwater samples in two urban catchments, which were collected manually or by automatic samplers. The impact of automatic samplers on E. coli concentrations in stormwater samples was further investigated by conducting a study of sampling line cross-contamination. The representativeness of suspended solids results obtained by the standard Total Suspended Solids (TSS) method was studied in urban bulk snow by assessing the ratio of suspended and settleable solids. TSS concentrations were compared to those obtained by other analytical procedures, including the Suspended Sediment Concentration (SSC) method and a newly introduced Multiple Filter Procedure (MFP). The MFP builds on the existing standard methods involving the filtration of whole water samples, but uses three filters with decreasing pore sizes to reduce filter clogging, and is designed to retain a broad range of solids, which is typical for stormwater. Finally, recognizing the affinity of indicator bacteria to suspended solids, both constituents were manually sampled in stormwater in four urban catchments during fall to assess their natural variation and correlation patterns between these contaminants.The comparison of samples collected manually and by automatic samplers yielded large differences in suspended solids concentrations, especially in the lower concentration range (0-100 mg/L), whereas the agreement between the two types of samples was within the analytical uncertainty (±30%) for all the four indicator bacteria. During the laboratory study, E. coli concentration in the first sample (following sudden bacteria concentration changes) were positively biased in automated samples due to the stormwater residue in the sampling line. When high E. coli concentrations were followed by low concentrations, the low concentrations were overestimated 10-20 times depending on the sampling line length (tested up to 5 m). The study findings should be helpful for improving field protocols for suspended solids and indicator bacteria sampling.The standard TSS analytical method underestimated solids in urban snow packs, because of high amounts of settleable particles remaining in situ, rather than leaving with snowmelt. The comparison between analytical procedures, including TSS, SSC and MFP yielded highly varying results for stormwater samples. The methods using whole water-samples, rather than aliquots withdrawn from such samples, as done in the case of TSS, produced more accurate estimates of solids concentrations, with a fairly good precision. The precision of the newly proposed MFP was generally better than ±10% and its results were comparable to those of standard methods using whole water samples, but the new procedure was less labourious. Consequently, the MFP was recommended for use when the total mass of solids in stormwater runoff is needed.The suspended solids and indicator bacteria concentrations in stormwater runoff varied from catchment to catchment and weak correlations were found between solids and bacteria, partly due to low concentrations of bacteria during the fall period. However, it was shown that the natural variation of the studied concentrations was affected by the sampling and the analytical method. Thus, the bias introduced during the stormwater quality monitoring process is relevant when assessing pollutant concentrations and the compliance of stormwater discharges with prescribed threshold values in the receiving waters.

Separate sewerage systems are designed so that the wastewater and stormwater are carried separately. However, in practice, untreated wastewater discharges to receiving waters are not that rare, impairing the quality of the receiving waters and increasing the risks to public health and aquatic organisms. The two main causes for such discharges are wastewater that enters stormwater sewers as well as sanitary sewer overflows (SSOs) from the separate wastewater sewers. The overall aim of this licentiate thesis is to review and improve the strategies used for detection of wastewater inputs to stormwater sewers and their location, and to address the issue of quantification of untreated wastewater discharges into the receiving waters by developing two methods: one for SSO discharges and one for the estimation of the wastewater amounts in stormwater sewers.A review of methods for detecting the entry of wastewater into stormwater sewers and the location of the entry points has been carried out by a critical literature review of the effectiveness of the current methods, their advantages, weaknesses and limitations in use. Additionally, an evaluation of the factors affecting the performance of a selected number of methods has been made from specially designed field studies, focusing on detectability of certain indicative pollution parameters and the effects of travel distance. The parameters selected based on those identified as being potentially the most useful in the literature review were E. coli, total coliform, Enterococci, conductivity, turbidity, TSS, and ammonium.The estimation of the volumes of untreated wastewater discharged into receiving waters was addressed by developing two methods: (1) volume estimation of SSO discharges based on already available infrastructure—backflow preventing flap gates—by performing full-scale studies to establish flow rating curves as a function of water head; and (2) estimation of wastewater ingress volumes into a stormwater system by using data from field studies as input to a Monte Carlo simulation to generate the probability distribution of possible fractions of wastewater in stormwater sewers.The reviewed indicator parameters and methods all demonstrated potential for detecting stormwater contamination by wastewater. However, there was no single method or strategy that would work under all conditions investigated. Human waste specific indicators—microbiological (adopted in microbial source tracking methods) and chemical markers (e.g., caffeine and carbamazepine)—as well as the Distributed Temperature Sensing method provided the best indication of wastewater pollution in the literature. However, these methods are currently beyond the capabilities of typical municipal expertise due to their costs and/or complexity and, therefore, combinations of methods that minimise the limitations of individual approaches have been identified in this thesis as the most effective provided these are tailored to specific cases.The travel distance from the point at which the wastewater entered the stormwater sewer is an important factor affecting the detectability of the investigated parameters, as the concentrations of the indicator parameters may change along the sewer length due to dilution, dispersion, physical, chemical, and microbiological processes. A Maximum Detection Distance (MDD) away from the origin of the input was determined which was in general shorter for the microbiological parameters than for the physicochemical parameters. Among the microorganisms analysed, Enterococci showed the shortest MDD of about 330–550 m, and E. coli — the longest of about 635–1245 m. Of the physicochemical parameters, the shortest MDD was for TSS (800–1130 m) and the longest for conductivity (1220–1560 m). MDD itself is not the main factor for selecting what parameters should be used, but rather how the sampling strategy for a particular parameter should be planned.The full-scale experiments on circular flap gates provided flow-rating curves for diameters of 200, 300, 400, 500 and 600 mm with high precision (R2>0.99). There are a large number of such gates installed in Sweden and the flow rating curves developed in this study could help practitioners to monitor SSO discharges with minimal onsite measurements (water head before and after the flap gate) in a reliable and inexpensive way.From the field study results, an equation was developed to estimate the volume of wastewater entering into the stormwater sewer. Monte Carlo simulation was selected as a means to increase the robustness of the outcome of the developed equation. The results of the simulation showed that the efficiency of the suggested method varied to a great extent depending on the selected combination of parameters: for example, for TSS and conductivity the percent error between the most probable and actual wastewater fractions in the sewer was less than 2%, while TSS combined with microbiological parameters failed as a combination to estimate the wastewater fraction in sewer.

Runoff generation in cold regions is characterized by snowmelt contributions to runoff during the periods of thawing and changing runoff patterns due to frozen ground. This thesis project aimed at addressing these challenges by advancing the procedures for winter urban runoff computations and the assessment of control measures during the winter/spring period, when the snowmelt and frozen soils dominantly impact runoff generation in the current and future climates. In such considerations, contributions of green/pervious areas to runoff and stormwater drainage systems were found particularly important and were addressed in one of the study components by conducting sensitivity analysis of the runoff modelling tool used, the MIKE SHE model. For this purpose, four runoff generation scenarios were defined, including the baseline reference scenario, a future climate scenario with up-scaled precipitation, and two scenarios with widely different infiltration rates. The results showed that the variations of infiltration capacity and the precipitation magnitude largely influenced runoff generation and impacted on the drainage system. Such impacts were measured by the number of flooded nodes and surcharged pipes, which greatly increased with decreasing infiltration capacity (described by Ks=1×10-10 m/s, which corresponds to the bedrock) and somewhat increased for increasing future precipitation (+20%). Projection of future climatological parameters to 2100 (i.e. temperature, precipitation and maximum hourly precipitation) were obtained for investigating seasonal changes in the town of Kalmar (southern Sweden). The results indicated that the seasonal precipitation patterns would become more similar in all the seasons, and the winter period would experience more changes in runoff generation, which would require more attention in stormwater management with respect to both snowmelt simulation and considerations of frozen grounds. To advance the understanding of urban snowmelt modelling, a literature review of selected snowmelt models was undertaken to identify which of them could be readily used, or easily modified, for improving the current snow modelling practice. For this purpose an urban snow cover classification (13 classes) was developed on the basis of the following considerations: human activities affecting snowmelt, land use, and the origin of deposited snow. Various snow covers in urban areas were then assessed and general recommendations were made for selecting the most appropriate model for specific studies, considering the study goals, constraints on the collection of field data, budget/time restriction, and the required accuracy. Urban runoff controls by green infrastructures, during the cold season, were studied for green roofs and infiltration facilities. Green roofs were found to be effective in warm weather, when they could counterbalance almost all the extra rainfall imposed by climate change, in a mixed land use catchment in Luleå, retrofitted with green roofs covering 30% of the catchment area. On the other hand, green roofs produced no benefits in the cold season with sub-zero temperatures and snow removal. Infiltration of runoff into two frozen engineered (sandy) soils, with slightly varying gradation, was studied in the laboratory for two values of the initial gravimetric water content (5 and 10%). Soil thawing process and restoration of infiltration capacity was slowed down by increasing water content and the content of fines in the soil. Thus, the soil with higher water content and finer gradation required more time for attaining full infiltration capacity after soil thawing. Practical implications of study results for bioretention facilities include the recommended use of coarser engineered soils, conservative estimation of infiltration rates, provision for bypassing of high flows, and fitting the facility with a valve-controlled under-drain facilitating bioretention drainage before the onset of freezing weather.

Heavy metals in urban stormwater runoff affect the ecological status of receiving surface waters. To avoid this, various stormwater treatment systems have been developed and implemented during the last 50 years. One of themost common and continuously popular systems is wet stormwater ponds. Another and relatively new type of system is stormwater biofilters. In wet stormwater ponds the function and design with respect to both waterquantity and water quality has been comprehensively addressed in scientific studies. Concerns today are more related to the fact that they serve as aquatic and wildlife habitats thereby posing a possible ecological risk. Incontrast, for stormwater biofilters, a knowledge gap regarding function and factors affecting their performance still exists.Understanding metal pathways in these two systems can support development of future stormwater management by identifying ways to improve the treatment of stormwater discharges and minimize risks of metals spreadingfrom treatment facilities to the natural environment. Thus, in this thesis metal pathways in wet stormwater ponds and stormwater biofilters were investigated in laboratory studies and field experiments to evaluate metal accu-mulation in different compartments of the two systems. For wet stormwater ponds the primary issue addressed in focus was their risk of affecting the wider environment whereas for stormwater biofilters was about their capaci-ty to improve stormwater runoff discharge. The study was performed by sampling resident fauna in wet stormwater ponds to evaluate bioaccumulation and biomagnification in wet stormwater ponds; sediment was sampled to estimate pollutant loads they receive; and mussel biomarkers were used to assess bioaccumulation over time in them. In addition, a laboratory study wasconducted to assess the reliability of mussels as biomarkers. To assess metal removal pathways and efficiency in stormwater biofilters, heavy metal concentrations were measured in the influent and effluent, as well as in thefilter material and the roots and shoots of stormwater biofilter vegetation.Mussel biomarkers were not confirmed to be a reliable method to assess the ecological state of wet stormwater ponds since they did not reflect the overall bioaccumulation in them. However, the use of resident fauna seemspromising for this purpose since the metal pollution load received by the wet stormwater ponds was reflected in the resident fauna. The results of this study indicated that despite being continuously loaded with heavy metalswet stormwater ponds have the ability to provide high biodiversity and thus ecosystem services without critically contaminating the resident fauna. However, with time wet stormwater ponds will likely end up constituting anecological risk to the surrounding environment.The investigated stormwater biofilters showed an overall efficient metal removal. The retained metals were trapped in the top layer of the filter material and in the roots and shoots of the biofilter vegetation. However, saltwas found to have a negative effect on stormwater biofilter performance inducing leaching of dissolved Cu and Pb and impeding plant metal uptake. Temperature variation did not generally affect metal removal but low tem-peratures caused a higher plant metal uptake than high temperatures. The presence of a submerged zone had a positive effect on stormwater biofilters, improving the overall metal removal from stormwater and plant metaluptake as well as plant health. By drawing parallels between the two studied systems, wet stormwater ponds will most likely be negativelyaffected by wintry conditions, constituting a risk for receiving waters at the same time as they are more likely to pose an ecological risk to the wider environment than stormwater biofilters. Use of stormwater biofilters wherepossible is therefore recommended, to improve future urban stormwater management. / Tungmetaller i dagvatten försämrar ekologiska statusen i mottagande ytvattnen. För att minimera negativa effekter har olika dagvattenbehandlingssystem utvecklats och implementerats i urbaniserade områden de senaste 50 åren. Ett av de vanligaste och än idag dominerande systemen är våta/kontinuerligt fyllda dagvattendammar. En annan och relativt ny systemtyp är dagvattenbiofilter. Beträffande våta dagvattendammar har funktion och design med avseende på både vattenkvantitet och vattenkvalitet studerats av många, medan en kunskapslucka fortfarande existerar när det gäller biofilter för dagvatten. För våta dagvattendammar är fokus av idag mera relaterat till det faktum att de fungerar som akvatisk habitat och livsmiljö for naturligt förekommande djur, vilket skapar en möjlig ekologisk risk.Att bättre förstå hur metaller beter sig i dessa två system kan bidra till att utveckla och förbättra framtida dagvattenhantering, genom att förbättra utsläpp och minimera risk för metallspridning. För att utvärdera metallackumulering i olika sektioner av våta dagvattendammar och dagvattenbiofilter utfördes laboratoriestudier och fältförsök. För våta dagvattendammar var frågan eventuella risker för omgivning, medan den för dagvatten biofilter var förmåga att förbättra utsläppskvalité.Musslor som biomarkörer bekräftades inte vara en tillförlitlig metod för att bedöma de ekologiska förhållandena i våta dagvattendammar eftersom de inte återspeglade den övergripande bioackumulationen. Dock verkar användningen av fastplacerad fauna lovande för detta ändamål eftersom den återspeglade de metallföroreningen som belastar våta dagvattendammar. Resultaten från denna studie visade att våta dagvattendammar, trots kontinuerlig belastning med tungmetaller, har förmåga till hög biologisk mångfald och därmed ekosystemtjänster utan att kritiskt förorena dammens fauna. Dock kommer våta dagvattendammar med tiden sannolikt att utgöra en ekologisk risk gentemot omgivande miljö.Dagvattenbiofilter visade sig ge effektiv metallrening med ackumulering av metall i såväl topplager (översta 5cm) av filtermaterialet som i rötter och skott av biofiltervegetation. Dock medförde salt en negativ effekt på biofilterprestanda, framkallande urlakning av löst Cu och Pb och även hindrande växtmetallupptag. Varierande temperatur påverkade i allmänhet inte metallreningen, men låga temperaturer orsakade jämfört med höga temperaturer ett ökat växtmetallupptag. Förekomst av en nedsänkt zon (SZ) gav en allmänt positiv effekt vad gäller metallrening, växtligt metallupptag och växternas välbefinnande.Jämförande studier de två systemen sinsemellan visar att våta dagvattendammar sannolikt påverkas negativt av vinterrelaterade villkor och därmed kan utgöra en risk för recipienter. Dessutom är de mer riskabla ur ekologisk synvinkel jämfört med dagvattenbiofilter. Det är därför rekommendabelt att använda dagvattenbiofilter när så är möjligt, för att förbättra den framtida stadens dagvattenhantering.

Climate change is regarded as one of the main future challenges implyingchanging hydrological conditions in urban areas. At the same time many urbanareas are expected to grow due to increasing population, which will most likelycause a higher level of urbanization. Combined effects of climatic changes andprogressing urbanization will have an impact on the abundance of pollutantsand the capacity for their transport. Due to this it is most likely that stormwaterquality will change as well. Effects of climatic changes, progressingurbanization and changing environmental policies on urban stormwater qualitywere studied by means of computer simulations for different test catchments inSweden. Scenarios accounting for such changes were developed and simulatedwith the Storm Water Management Model (SWMM), in which stormwaterquality was described by total suspended solids (TSS) and two heavy metals,namely copper and zinc. The simulation results showed that pollutant loadsdepended mainly on rainfall depth and intensity, but not on antecedent periods.Storms with low to intermediate depths and intensities showed the highestsensitivities to climatic changes and the reason for that was the contribution ofpervious areas and pollutant supply limited conditions. Catchments with lowimperviousness were most sensitive to climatic changes, but the total TSSloads were low compared to catchments with high imperviousness. Generallypollutant loads increased due to climatic changes characterized by higherdepths and intensities of rainfall in future scenarios. Furthermore stormwaterquality changed significantly for scenarios considering a progressingurbanization. A changing catchment area and impervious fraction caused highchanges in runoff volumes and pollutant loads. Thus changes in suchcatchment characteristics were identified as the most influential factors; inmost of the cases changes caused by climate change were exceeded.Environmental policies, as for example the reduction of directly connectedimpervious areas were effective in reducing runoff volumes and consequentlypollutant loads. Furthermore pollutant source controls, including materialsubstitution, were identified to be an effective tool for reducing pollutant loadsand improving stormwater quality. Generally changes produced by climaticchanges were small compared to the effects of changes in land use and this hasimplications for the management of stormwater quality. / Klimatförändringen anses vara en av de viktigaste framtida utmaningarna och innebär förändrade hydrologiska förhållanden i stadsområden. Samtidigt förväntas många stadsområden växa till följd av ökande befolkning, som med största sannolikhet kommer att orsaka en högre grad av urbanisering. De kombinerade effekterna av klimatförändringar och urbanisering kommer att ha en påverkan på förekomsten av föroreningar. På grund av detta är det också mest troligt att dagvattenkvaliteten kommer att förändras. Effekter av klimatförändringar, urbanisering och förändrad miljöpolitik kring hantering av urban dagvattenkvalitet studerades med hjälp av datorsimuleringar för olika testavrinningsområden i Sverige. Scenarier som beskriver sådana förändringar har tagits fram och simulerats med en modell som kallas ’’Storm Water Management Model’’ (SWMM). I modellen beskrevs dagvattenkvaliteten av totalt suspenderat material (TSS) och två tungmetaller, nämligen koppar och zink. Simuleringen visade att föroreningsmängder främst berodde på nederbördsmängd och -intensitet, men däremot inte på torrperioder. Regn med låg till medellåg mängd och intensitet uppvisade den högsta känsligheten för klimatförändringar. Anledningen till det var bidrag från permeabla ytor och begränsningar av föroreningsutbud. Avrinningsområden med låg andel av hårdgjorda ytor var mest känsliga för klimatförändringar, men totala TSSmängder var låga jämfört med avrinningsområden med hög andel av hårdgjorda ytor. Generellt ökade föroreningsmängderna till följd av klimatförändringar som karaktäriserades av högre mängd och intensitet av nederbörd i framtidsscenarier. Dessutom förändrades dagvattenkvaliteten avsevärt för scenarier som beskriver en urbanisering. En förändring av area och andel av hårdgjorda ytor orsakade stora förändringar i avrinningsvolymer och föroreningsmängder. Förändringar av avrinningsområdenas egenskaper har identifierats som de mest inflytelserika faktorerna, i de flesta fall med större påverkan än klimatförändringar. Miljöpolitik, som till exempel en minskning av direkt anslutna hårdgjorda ytor, var effektiva för att minska avrinningsvolymer och därmed föroreningsmängder. Begränsning av föroreningskällor, inklusive materialsubstitution, identifierades också till att vara ett effektivt sätt för att minska föroreningsmängder och förbättra dagvattenkvaliteten. Generellt såg man att förändringar i dagvattenkvaliteten orsakade av klimatförändringar var små jämfört med effekterna av förändringar i markanvändning. Detta får konsekvenser för hanteringen av dagvattenkvaliteten.