Stormwater runoff generated from urban areas can be a source of contamination and may negatively impact receiving waters. Best management practices, including the use of treatment wetlands, are recommended to minimize impacts and maintain the quality of water bodies receiving stormwater discharge. This study focuses on the viability of a natural wetland in the treatment of urban runoff. Kuhn Marsh is a natural urban wetland located in Dartmouth, NS. The wetland is approximately 2 ha in size and the primary inlet is a stormwater outfall servicing a 28 ha urban drainage area. Kuhn Marsh has been receiving stormwater generated from the urban drainage area for decades. A wetland drainage area of approximately 9 ha contributes to surface runoff downstream of the wetland inlet. Project objectives are defined as: (i) characterization of the hydrology and hydraulics of the wetland system, (ii) characterization of contaminant fluxes within the wetland system, and (iii) analysis of the treatment performance of Kuhn Marsh. Research strategies used to achieve project objectives include physical and hydrologic characterization of the wetland and contributing watersheds as well as surface and ground water quality analysis. Monitoring was conducted in the wetland during both baseflow and stormflow conditions from May 2011 through October 2012, with the exception of November 2011 to January 2012. Surface water samples were analyzed in the laboratory for TSS, TOC, TN, TP, turbidity, E.coli, and a suite of heavy metals including Fe, Pb, Cu, Cd and Zn. In-situ surface water monitoring included DO, temperature, conductivity and pH. Groundwater samples were analyzed for E.coli and microbial source tracking was performed on all well samples in addition to samples from the inlet and outlet of the wetland. Results from the well samples and the wetland outlet were inconclusive, however the wetland inlet showed human source bacteria indicating potential sewer cross connections within the stormwater system. It was determined that the wetland is an area of groundwater discharge, with groundwater accounting for an average of 50% of the volume discharging through the outlet control structure. Largely due to groundwater influence, Kuhn Marsh shows no peak flow dampening or volume reduction between inlet and outlet. Minimal hydraulic retention times, between 2 and 4 hours, were calculated during stormflow conditions, indicating potential short circuiting of flows through the wetland. Wetland treatment performance was analyzed on a concentration and mass reduction basis and on the number samples that exceeded parameter guidelines at the outlet of the wetland. Guideline exceedances were reported for the majority of samples taken and increases in concentration between inlet and outlet resulted in a larger number of samples exceeding guidelines at the outlet. Despite dilution from groundwater discharge, minimal to no concentration reduction was reported between the inlet and outlet of the wetland. Mass reduction did not occur between the inlet and outlet and Kuhn Marsh was found to be a source of all contaminants sampled. Results of this study show that Kuhn Marsh is no longer acting as a reservoir for stormwater contaminants and, based on the fact that the wetland has been receiving stormwater input on the order of decades, study results may be indicative of the long-term treatment capacity of a stormwater treatment wetland. In the future, comprehensive sampling of groundwater is recommended to determine if contaminants are entering the wetland via groundwater discharge, and if possible, surface water sampling should be conducted on a finer scale to better estimate mass fluxes and contaminant loading rates.

Master of Landscape Architecture / Department of Landscape Architecture/Regional and Community Planning / Timothy D. Keane / All along the Gulf Coast, wetlands are disappearing due to saltwater intrusion from the draining of freshwater wetlands. Louisiana has about 40 percent of the coastal wetland in the lower 48 states but is currently losing approximately 24 square miles of wetlands a year (Louisiana Coastal 2009). Studies have shown that wetlands can help reduce the impact of a storm surge during a hurricane and have a cleansing ability from air to water. An increase in hurricane intensities due to climate change will likely result in bigger storm surges. Without wetlands to diffuse storm surges, disasters like Hurricane Katrina will recur. Cities spend millions of dollars on treating wastewater and stormwater with facilities and chemicals. Wetlands can treat wastewater through different processes without using chemicals, thus reducing costs and increasing sustainability. Bayou Bienvenue is a wetland located in New Orleans. This wetland was once a freshwater cypress swamp, but due to saltwater intrusion from the construction of Intracoastal Waterway and Mississippi River Gulf Outlet, has turned into a brackish lake. This wetland is separated from the Lower 9th Ward with a levee that creates a visual barrier which results in local residences not knowing that there is a former wetland behind the levee. Bayou Bienvenue’s Ecological Park’s discovery center with educational programs about successional wetland landscapes will educate people about the importance of wetlands to New Orleans. The restored of the bayou will be a landscape that functions as infrastructure through the treatment of stormwater and wastewater. The bayou will aid in reducing storm surge impacts, provide wildlife habitat, become part of schools’ curricula within the 9th Ward, stimulate the local economy and provide a community park for people to enjoy. Bayou Bienvenue’s Ecological Park will help spur further wetland projects of this caliber in and around New Orleans.

Oyster shells are normally applied in wastewater treatment in the form of a powder; but the possibility of whole oyster shells removing metal ions in stormwater has not been investigated. The objectives of this research are to assess the application of whole oyster shells for removing metals in low concentration solutions and to explore the influence of the following factors: surface area of shells, initial concentration and exposure time, on removal efficiency. Experimental results demonstrated very good removal efficiency by oyster shells for removing copper, followed by cadmium and zinc; but was not effective in hexavalent chromium removal. Up to 70% removal can be reached in just one hour for copper with initial concentrations of 0.2ppm with 550cm2 of surface area (SA) of shells in a beaker experiment treating two-liter solutions (with an accompanying pH increase from 5 to 6.42). A removal efficiency (RE) of 57.7% and 33.3% was found for cadmium and zinc, respectively, with one day contact using shells of 300cm2 SA treating one liter of the lowest concentration solution; while only 14.3% was achieved for chromium under the same conditions. Mid-scale experiments with continuous inflow based on the 6-hour Saanich Design Storm demonstrated an 85.5% and an 83.9% RE of cadmium and copper in one day’s worth of contact time. There was no removal but in fact an increase in chromium and zinc was found for the mid-scale experiment. There was a positive relationship between initial concentration (IC) and removal efficiency for copper and zinc, but a negative relationship for chromium, while no relationship was found for cadmium. Up to 80% of copper can be removed at IC of 2.4ppm compared to 60% with IC of 0.65ppm with same amount of shells (by surface area). RE of 70%, 75% and 83% was observed for IC of 0.3ppm, 0.58ppm and 1.07ppm for zinc, respectively, with 154 cm2 SA. When IC of chromium is reduced from 1 ppm to 0.2ppm, RE tends to drop from 60% to 26%. There was also a positive relationship between SA and RE, and ET and RE. However, after a certain exposure time, increase in RE was negligible and sometimes, desorption would occur. Additionally, when the difference in surface area is small, the influence of this factor on RE was also small. When treating certain ranges of solution concentration, the effect of surface area on RE is difficult to distinguish. Moreover, the role of HRT in stormwater systems was not clearly found. / Graduate

The Mulden-Rigolen system, a new urban stormwater management system implemented in Germany, has been examined in this study. The aim of this new system is to replace traditional sewer system for urban road runoff, by infiltrating the incoming water locally through a dual underground system: an active top soil layer and a deeper trench of packed gravel. For each site using this system, the characteristics of the soils in terms of pH, texture, organic matter, infiltration rate as well as Heavy Metals (Cd, Cr, Cu, Pb, Zn) and Phosphorus soil concentrations were successfully determined. The measured values for the soil characteristics were still, after an operation time of up to 15 years for some sites, globally in the range of the recommendation of the German Association for Water, Wastewater and Waste, except for organic matter in some sites, suggesting the need for a more cautious maintenance. Concerning heavy metals and phosphorus content, no alarming soil contamination was observed indicating that the studied “Mulden-Rigolen” systems were still acceptable in terms of soil pollution after several years of use, according to the Danish standards. If this system seemed to have a good flexibility and adaptability to different urban land uses, its treatment efficiency still has to be fully assessed. Indeed, only a primary evaluation of its performance war carried out through a simplistic model which brought up some questions about pollutant retention (especially in case of Zn). Further research (intact soil columns experiments, sequential extractions, on-site runoff sampling) would be necessary to fully determine how well this system works in terms of water treatment.

Highway runoff and its pollutants are of growing concern. These pollutants require treatment as their concentration often are increased. A common removal method is the use of sedimentation ponds that removes particulates through gravity. However, sedimentation does not remove the pollutants inside very fine particulate material or the dissolved pollutants. An additional treatment step is required to remove these pollutants and necessary to reach more stringent discharge demands. In this report, the removal of metals was studied on stormwater after sedimentation in a dam in the existing treatment facility at Lilla Essingen. The runoff reaching the facility largely comes from the highway Essingeleden, which has an annual average daily traffic of 140 000 vehicles. The commercial filter material D-Rainclean was used in this study, which started in late August 2021 and ended in November 2021. The filter material was filled equally into two separate filter wells. After sedimentation, the runoff was pumped to each filter well with a constant flow of around 600 L/h. This load caused a hydraulic retention time of about 41 minutes. The stormwater flowed through the filter material from the bottom towards its surface, i.e. upward flow, creating saturated conditions. The removal of dissolved zinc (Zn) was just above 90% while dissolved copper (Cu) was in average removed by 50 %. The effluent concentrations of Cu were generally above the regulation limits set by Järfälla municipality and Gothenburg city. Dissolved calcium (Ca) and potassium (K) was released by the filter material itself through the entire trial and dissolved vanadium (V) was released initially but decreased continuously and reached close to zero at the end of the trial. Influent stormwater concentrations of sodium (Na), magnesium (Mg), chromium (Cr) and molybdenum (Mo) was unaffected by the filter as was the dissolved fraction of nickel (Ni), iron (Fe) and aluminium (Al). Particulate material was removed by the filters. However, at the end of the trial a release of particulate material was observed. This is likely caused by filter erosion that occurred through the combination of clogging and the high surface load. Surface loading and retention time was elevated during the trials. The sharp increase of suspended solids loads in November followed by increased filter pressure drop shows the importance of having a functional sedimentation to prevent physical clogging of the filter media. / Dagvatten från vägar och föreningarna inuti detta vatten är ett ökande problem. Avskiljningen av dessa föroreningar är en utmaning, en konventionell reningsmetod är användandet av sedimenteringsdammar för att avskilja de partikulära föroreningarna. Med hårdare krav på utsläpp av metaller krävs ytterligare reningsmetoder för att hantera de lösta metallföreningarna i dagvatten, vilka ej kan avskiljas med sedimentering. Av speciellt intresse är de lösta fraktionerna av zink (Zn) och koppar (Cu). Zink (Zn) och koppar (Cu) är av störst intresse när de förekommer till stor del i löst form, varvid de ej tas bort i sedimenteringsdammar. Försöket i den här rapporten testar avskiljningsförmågan hos det reaktiva filtermaterialet D-Rainclean under hög ytbelastning, 0,35 m/h och kort uppehållstid, 41 min. Dagvattnet kommer från ett område på 1,76 ha där majoriteten av ytan består av hårt trafikerad väg. Dagvattnet når två separata reaktiva filter efter försedimentering. Filtermaterialet ligger fördelat i två filterbrunnar, F1 och F2, med samma mängd D-Rainclean.Totalt passerade ungefär 3000 provolymer genom filtren. Den totala mängden suspenderat material som belastade filtren var 35 kg. Efter 600 porvolymer uppstod ett tryckfall på 40 cm för både F1 och F2. En 60 cm tryckpelare nåddes i båda filtren efter ungefär 1000 till 1200 porvolymer. Under flöden med hög turbiditet mot slutet av försöket nådde tryckfallet 110 cm för F1 och över 80 cm för F2.Avskiljningen av löst Zn var över 90%. Avskiljning av löst Cu var runt 50 %. Koncentration av Cu efter de reaktiva filtren översteg de riktvärden som satts av Järfälla kommun samt Göteborg stad. Löst kalcium (Ca) och kalium (K) släpptes av filtren under hela försöket. Löst vanadin (V) släpptes också av filtret men halten V minskade kontinuerligt och nådde till slut en koncentration nära detektionsgränsen. Inkommande koncentrationer av natrium (Na), magnesium (Mg), krom (Cr) och molybden (Mo) var opåverkade av filtret, likaså den lösta fraktionen av nickel (Ni), järn (Fe) och aluminium (Al). Majoriteten av metallernas partikelfraktioner avskildes av filtren men mot slutet började filtren släppa partikulärt bundna metaller.Uppehållstiden för vattnet i filtret var antagligen för kort för att få hög avskiljning av Cu varför den föreslås att den förlängs om det är praktiskt möjligt.

In the recent century, a process of urbanization has increased globally. Previously rural or natural land have been converted into impervious surfaces to make way for housing, industries, and roads. This anthropogenic process has resulted in an increased amount of surface runoff from precipitation, so-called stormwater. Stormwater can accumulate a range of pollutants when it flows over the impervious surfaces of our cities. These pollutants can have a negative impact on the lakes and streams that receive the stormwater from the urban environments. To reduce the environmental problems associated with the content of stormwater, various techniques have been developed for stormwater treatment, with the aim of reducing the pollutant load in the runoff before it enters the receiving waterbody. One such technology is stormwater biofiltration, also known as bioretention. Stormwater biofilters were developed in the USA in the early 90's and they utilize the natural water remediation properties of plant-soil systems. They are generally characterized by a vegetated submerged filter bed with an underlying drainage layer. They have shown to be an effective method for stormwater pollutant removal. The treatment processes take place both in the vegetation and in filter material. As th ematerial choices and design of the biofilters can vary, so can its treatment performance. Stormwater biofilters have grown in popularity in the last decades since their development and numerous studies have been conducted to evaluate the systems’ treatment efficiency. However, knowledge gaps still exist regarding their implementation in colder climates and the suitability of different configurations and materials. This study examines the removal performance of total and dissolved heavy metals (Cd (cadmium),Cu (copper), Pb (lead) and Zn (zinc)), phosphorus, nitrogen and total suspended solids (TSS) in three stormwater biofilters in a Swedish climate, located in central Malmö. The current biofilters are designed with different configurations of their filter media and are built with 1) sand-basedfilter material 2) sand-based filter material with a submerged zone and 3) filter media consisting of 50% sand-based material in combination with 50% pumice. The results showed that the treatment capacity of the biofilters with a filter media of only sand (biofilter S) and with sand as well as a submerged zone (biofilter S_SZ) was similar for all pollutants. The reduction of total levels of metals (> 85 %) and TSS (>90 %) was consistently high and similar to levels achieved in previous studies for both temperate and colder climates. The removal of dissolved metals was lower in comparison to the removal of the total metal fractions, but the dissolved fractions were still generally reduced in the effluent. A positive removal of total phosphorus and total nitrogen was overall displayed in the effluent from the two biofilters; however,leaching was shown for the dissolved fractions. For nitrogen (N) species, the concentrations in the runoff were generally below the detection limit for the analysis making it difficult to establish probable removal percentages. For the biofilter S_P, which contained a mix of sand and pumice, the removal capacity was lowerfor all parameters compared to the other designs. Overall, the pollutant removal performances are regarded to be satisfactory for biofilters S andS_SZ and their implementation suitable for the given site. However, further investigations should be performed during warmer seasons, especially regarding the removal of nutrients.

No description available.

Green adsorption media with the inclusion of renewable and recycled materials can be applied as a stormwater best management practice for copper removal. A green adsorption media mixture composed of recycled tire chunk, expanded clay aggregate, and coconut coir was physicochemically evaluated for its potential use in an upflow media filter. The results found that the use of the green adsorption media mixture in isolation or the coconut coir with an expanded clay filtration chamber could be an effective and reliable stormwater best management practice for copper removal. A suite of tests were conducted on the media mixture and the individual media components including studies of isotherm, reaction kinetics, column adsorption and reaction kinetics. Batch adsorption tests revealed that the media and media mixture follow both the Freundlich and Langmuir isotherm models and that the coconut coir had the highest affinity for copper. A screening of desorbing agents revealed that hydrochloric acid has good potential for copper desorption, while batch tests for desorption with hydrochloric acid as the desorbing agent showed the data fit the Freundlich isotherm model. Reaction kinetics revealed that the adsorption reaction took less than 1 hour to reach equilibrium and that it followed pseudo-second order kinetics for the mixture and coconut. Desorption kinetic data had high correlation with the pseudo-second order model and revealed a rapid desorption reaction. Batch equilibrium data over 3 adsorption/desorption cycles found that the coconut coir and media mixture were the most resilient and demonstrated that they could be used through 3 or more adsorption/desorption cycles. The coconut coir also performed the best under dynamic conditions, having an equilibrium uptake of 1.63 mg?g-1, compared to 0.021 mg?g-1 at an influent concentration of 1.0 mg?L-1 and a hydraulic retention time of 30 minutes. A physical evaluation of the media found the macro-scale properties, such as particle size distribution and mass-volume relationships, and observed the micro-scale properties such as surface and pore microstructures, crystalline structures, and elemental composition. FE-SEM imaging found a strong correlation between the porosity of the micro pore structure and the adsorptive capacity. The equilibrium and dynamic adsorption testing results were confirmed by elemental analysis, which showed measureable quantities of copper in the coconut coir and media mixture after adsorption followed by partial desorption. A new scaling-up theory was developed through a joint consideration of the Damköhler and Péclet numbers for a constant media particle size such that a balance between transport-controlled and reaction-controlled kinetics can be harmonized. A series of column breakthrough tests at varying hydraulic residence times revealed a clear peak adsorptive capacity for the media mixture at a Damköhler number of 2.7. The Péclet numbers for the column breakthrough tests indicated that mechanical dispersion is an important effect that requires further consideration in the scaling-up process. However, perfect similitude of the Damköhler number cannot be maintained for a constant media particle size, and relaxation of hydrodynamic similitude through variation of the Péclet number must occur.

For high groundwater table areas, stormwater wet detention ponds are utilized as the preferred stormwater management throughout the state of Florida. Previous research has found that accumulations of nutrients, algae, heavy metals, pesticides, chlorophyll a, fecal coliform bacteria and low concentrations of dissolved oxygen (DO) are common characteristics of stormwater wet detention ponds. Although these pollutant levels are not regulated within the ponds, states are required to compute the pollutant load reductions through total maximum daily load (TMDL) programs to meet the water quality requirements addressed by the Clean Water Act (CWA). In this study, field sampling data of stormwater ponds throughout Florida are presented to identify concentration levels of the main contaminants of concern in the discharge of wet detention ponds. Sampling was done to identify possible sources, in addition to possible removal mechanisms via the use of specific sorption media. Nutrients were found as a main problematic pollutant, of which orthophosphate, total phosphorus, ammonia, nitrate, and total nitrogen were targeted whereas heavy metals exhibited minor concerns. Accumulation of high nutrient concentrations may be mitigated by the adoption of best management practices (BMPs) utilizing biosorption activated media (BAM) to remove phosphorus and nitrogen species through physical, chemical, and biological processes. This study aims to increase overall scientific understanding of phosphorus removal dynamics in sorption media systems via Langmuir and Freundlich isotherms and column studies. The removal of phosphorus (P) was proven effective primarily through chemophysical processes. The maximum orthophosphate adsorption capacities were determined under varying conditions of the media within the columns, which were found up to 0.000534 mg-P adsorbed per gram BAM with influent concentrations of 1 mg∙L -1 orthophosphate in distilled water and 1 hour hydraulic residence time (HRT). When using iv spiked pond water under the same conditions, the adsorption capacity was increased about 30 times to 0.01507 mg-P∙g -1 BAM presumably due to the properties and concentrations of ions affecting the diffusion rate regulating the surface orthophosphate reactions. These equilibrium media uptake values (q) were used to calculate the life expectancies of the media under varying HRT and influent concentrations of treatment. Chemophysical and biological removal capabilities of the media for total nitrogen, ammonia, and nitrate were effective in columns using 1100 g of BAM. In flow-through column conditions, ammonia had a consistent ~95% removal while effluent nitrate concentrations were highly variable due to the simultaneous nitrificationdenitrification processes once an aerobic-anaerobic environment was established. Batch column experiments simulating no-flow conditions within a media bed reactor resulted in orthophosphate removals comparable with the continuous flow conditions, increased total phosphorus effluents indicative of chemical precipitation of orthophosphate, decreased ammonia removal, and increased nitrate removal. Due to a biofilm’s sensitivity to even low copper concentrations and accumulation in ponds, a copper sorption media mix of "green" materials was generated. Freundlich and Langmuir isotherm tests concluded a successful mix resulting in copper removal efficiencies up to 96%.

Development of cities, new buildings and other impervious surfaces entails increased stormwater flows, volumes and pollutant loads. Heavy metals, nutrients, sediments and salt are common pollutants in stormwater. The conventional way to manage stormwater, which is by discharge to the receiving water body via a sewage network, will not be sufficient for mitigating high flows, flood risks and pollution export. Thus, Low Impact Development (LID) stormwater facilities, such as stormwater biofilters, are built in an increasing rate in Sweden and worldwide. The main function of a stormwater biofilter is water quality treatment, which is achieved when stormwater percolates through a vegetated filter media. Sometimes a pre-treatment facility is installed before the biofilter to reduce the sediment load on the biofilter and extend its life-length. However, there are knowledge gaps regarding pollutant removal in biofilters and the role of associated pre-treatment facilities. In this study the impact of a pre-treatment facility, calcium carbonate as amendment in the filter media and vegetation was investigated regarding treatment of heavy metals (Cd (cadmium), Cu (copper), Pb (lead) and Zn (zinc)), phosphorus and total suspended solids. To do this, influent and effluent stormwater samples from an existing biofilter in Sundsvall were analysed and evaluated regarding removal performance of the above-mentioned pollutants.  In general, the stormwater biofilter facility (including pre-treatment) removed total metals well while the removal of the dissolved fraction showed higher variations. Influent concentrations of TP were always higher than effluent concentrations. Leaching of phosphate repeatedly occurred from the filter sections. The mean removal of TSS was high (96.9%). CaCO3 as amendment in the filter material had a beneficial effect on the overall metal removal of the stormwater facility. Although leaching of phosphate occurred from all filter sections, the leaching was lowest from the section with CaCO3,indicating possible benefits of CaCO3 as amendment. CaCO3 did not seem to affect the mean total phosphorus removal significantly. Removal of total metals seemed to be improved by vegetation, but the removal of dissolved metals, total phosphorus and phosphate did not seem to be enhanced by vegetation. The filter section with vegetation and without CaCO3 amendment contributed with the highest effluent concentrations of total phosphorus and phosphate (leaching), considering that vegetation released more phosphate that it captured. The main treatment of the stormwater pollutants occurred within the biofilter and both positive and negative removal of all pollutants was observed by the pre-treatment facility. The result showed that the pre-treatment facility was most beneficial for removal of dissolved metals. / Utvecklingen av städer, nya byggnader och andra hårdgjorda ytor ökar både mängden dagvatten och föroreningshalterna. Vanligt förekommande föroreningar i dagvatten är tungmetaller, näringsämnen, sediment och salt. Det traditionella sättet att hantera dagvatten är genom avledning via avloppsnätet till närliggande recipient, men med den förändrade kvalitén och kvantitet på dagvatten blir kapaciteten i det befintliga ledningsnätet otillräckligt för de ökade flödena och föroreningsinnehållet. Därför byggs bland annat dagvattenbiofilter, som är en typ av Low Impact Development (LID), i en ökande takt i Sverige och globalt. Huvudsyftet med dagvattenbiofilter är dagvattenrening, vilket uppnås när dagvattnet filtreras genom en filterbädd med växter. För att minska (sediment)belastningen och förlänga livslängden på biofiltret kan ibland en förbehandlingsanläggning placeras i före biofiltret. Dock finns det fortfarande kunskapsluckor om reningspotentialen i biofilter och betydelsen av en förbehandlingsanläggning. I den här studien undersöktes betydelsen av en förbehandlingsanläggning, kalciumkarbonat som tillsats i filter materialet och växter på biofiltret för reningen av tungmetaller (Cd (kadmium), Cu (koppar), Pb (bly) och Zn (zink)), fosfor och totalt suspenderat material. För att undersöka detta analyserades och utvärderades dagvattenprover på inkommande och utgående vatten från ett biofilter i Sundsvall, med avseende på reningsprestation av ovan nämnda föroreningar. Resultatet visade att biofiltret (med förbehandlingsanläggningen inkluderad), renade totala metaller bra medan reningen av lösta metaller varierade mer. Inkommande koncentrationer av totalfosfor var alltid högre än utgående koncentrationer och fosfat lakades kontinuerligt ut från filtersektionerna. Den genomsnittliga reningen av TSS var hög (96,9%). CaCO3 som tillsats i filtermaterialet hade en positiv effekt på reningen av totala och lösta metaller i biofiltret. Fosfat lakades ut från alla filtersektioner, men urlakningen var lägst från filtersektionen med CaCO3, vilket tyder på möjliga positiva effekter det som tillsats i filtermaterialet. CaCO3 verkade inte öka genomsnittliga reningen av totalfosfor signifikant. Vegetationen verkade öka reningen av totala metaller men inte reningen av lösta metaller, totalfosfor eller fosfat. Filtersektionen med vegetation men utan CaCO3 genererade de högsta utgående koncentrationerna av totalfosfor och fosfat (urlakning), vilket tyder på att vegetation avgav mer fosfor än den tog upp. Den dominerande reningen av dagvattenföroreningarna skedde inuti biofiltret och både högre och lägre koncentrationer av samtliga föroreningar observerades efter förbehandlingsanläggningen. Resultatet visade att förbehandlingsanläggningen var mest effektiv för reningen av lösta metaller.