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Feine abfiltrierbare Feststoffe (AFS63) sind ein neuer Parameter zur Bewertung von Niederschlagsabflüssen in Deutschland. Während die gesamten abfiltrierbaren Feststoffe (AFSges) gemäß DIN 38409-2 analysiert werden können, fehlt bisher eine genormte Methode zur AFS63-Bestimmung. Hierzu müssen methodenspezifische Einflussfaktoren auf die AFS63-Wiederfindung von Feststoffen, die in Verkehrsflächenabflüssen vorliegen, im Labor untersucht werden. In einem mehrstufigen Verfahren wurden Feststoffmaterialien in bekannter Korngrößenverteilung und Organikanteilen aus Straßenstäuben hergestellt und systematisch getestet. Hiermit wurden die Einflüsse verschiedener Filtermaterialien, Siebmethoden und Dispergiermethoden auf die AFSges- und AFS63-Bestimmung in Flüssigproben mit zudosierten Feststoffmaterialien untersucht. Anhand der Laborversuche wurde festgestellt, dass sowohl Glasfaser- als auch Membranfilter als Filtermaterialien geeignet sind. Drei Siebmethoden zur Abtrennung der groben Feststofffraktionen (AFSgrob) wurden getestet und Empfehlungen zur Anwendung formuliert. Je nach Dispergierung kommt es bei einigen Feststoffmaterialien zu Über- und Unterbefunden an AFS63, wobei die händische Methode „kräftig Schütteln“ die höchste Wiederfindungsrate hatte.

Road-deposited sediments (RDS) contain metals that can pollute receiving waters during precipitation events. The concentration of particle-bound metals tends to increase with decreasing particle size. In terms of metal load, the highest loads were often located in the medium range of particle sizes. Many studies have used varying or undocumented sieving techniques without showing the quality of the separation process. This is important as different particle size classes are documented with different pollution contents and loads. This knowledge builds the foundation for the selection of best management practices to improve receiving water quality. Based on the knowledge that the separation of particle sizes by the commonly applied dry sieving can be methodologically biased, this study compares particle size classes obtained by dry and wet sieving methods. The aim of the study was to show the methodological influence of the sieving process on the particle-size distribution (PSD) with focus on the metal distribution within RDS. Therefore, concentrations of Cu, Zn and Pb were determined and loads were calculated per sieve fraction after wet and dry sieving. Wet sieving causes a shift of the PSD to finer particles and both metal concentrations and loads are significantly higher especially in the smallest sieve fractions. Fine, highly polluted particles remained in coarser sieve fractions after dry sieving. This leads to diverging metal contents and especially loads in the fractions > 250 µm and thus lead to varying conclusions from the results. The results of the comparison of sieving methods however confirmed the relevance of the fine particle fractions in terms of best management practices. The fraction < 40 µm showed highest concentration and load in RDS after wet sieving. The results also showed the considerable influence of the sieving method used and the need to document laboratory methods as part of good laboratory practice.

Pollutants (e.g. heavy metals) are to a large extent bound to particles in runoff from traffic areas. Sedimentation is the prevailing process of treatment in most cases. The effectiveness of treatment depends largely on the characteristics of the particles, especially their size and density. Road-deposited sediments (RDS) are the main source of solids in runoff. The sizes and density vary over a wide range, as the particles are composed of mineral and organic components of different origin (e.g. tire and road wear, plant debris, erosion from surrounding areas, atmospheric deposition). While many previous studies have dealt with particle-size distributions, there are still relatively few studies on density. The aim of this study was to investigate the relationship between particle size, organic content and density in RDS on a large data set from different sites and the influence of site-specific conditions on the composition. In addition, it should be checked whether the loss on ignition (LOI) is suitable as a surrogate parameter for density. Density was obtained by gas pycnometry, LOI by ignition in a muffle furnace at 550 °C. In total, 85 RDS samples were collected at 11 sites over a 5 year period and sieved into ten sieve fractions2000 μm. Each sieve fraction was analyzed for LOI and density (n = 848). This novel data set covers a wide range of boundary conditions in terms of traffic intensity and surrounding vegetation. The results show that there is a strong negative linear correlation of density and LOI independent of particle size2000 μm (R

Separation of particulate matter (PM) is the most important process to achieve a reduction of contaminants present in road runoff. To further improve knowledge about influencing factors on the settling of road-deposited sediment (RDS), samples from three sites were collected. Since particle size distribution (PSD) has the strongest effect on settling, the samples were sieved to achieve comparable PSDs so that the effects of particle density, shape, fluid temperature, and deicing salt concentration on settling could be assessed using settling experiments. Based on the experimental data, a previously proposed model that describes the settling of PM was further developed and validated. In addition, RDS samples were compared to a standard mineral material, which is currently in use to evaluate treatment efficiency of stormwater quality improvement devices. The main finding was that besides PSD, particle density is the most important influencing factor. Particle shape was thoroughly described but showed no significant improvement of the prediction of the settled mass. Temperature showed an effect on PM settling, deicing salts were negligible. The proposed models can sufficiently predict the settling of RDS in settling column experiments under varying boundary conditions and are easily applicable.

Dezentrale Behandlungsanlagen für Verkehrsflächenabflüsse werden zum Rückhalt von Feststoffen, organischen Stoffen wie Kohlenwasserstoffe und Schwermetallen verwendet. Daneben wird in einigen Einzugsgebieten aus Gründen des Gewässerschutzes auch ein Rückhalt von Nährstoffen, wie Phosphor, gefordert. Spezielle Filtermaterialien können zum gleichzeitigen Rückhalt verschiedener Stoffgruppen geeignet sein. Zwei dieser Materialien, ein granuliertes Eisenhydroxid (GEH) und ein neu entwickeltes Calciumsilikat, wurden anhand von Schüttel- und Säulenversuchen im Labor auf ihren jeweiligen Rückhalt von Kupfer, Nickel, Zink und ortho-Phosphat untersucht. Zusätzlich wurden die Material-Eigenschaften des Calciumsilikats bestimmt sowie die Einflüsse verschiedener Zulaufkonzentrationen und Kontaktzeiten auf den Rückhalt ermittelt. Die Ergebnisse zeigen, dass sich beide Materialien für die Behandlung der untersuchten Stoffe eignen, wobei zusätzliche Labor- und Felduntersuchungen zur Quantifizierung weiterer Einflüsse auf den Rückhalt notwendig sind.

In recent years, there has been a significant increase in the development and application of technical decentralized filter systems for the treatment of runoff from traffic areas. However, there are still many uncertainties regarding the service life and the performance of filter materials that are employed in decentralized treatment systems. These filter media are designed to prevent the transport of pollutants into the environment. A novel pilot-scale test method was developed to determine - within a few days - the service lives and long-term removal efficiencies for dissolved heavy metals in stormwater treatment systems. The proposed method consists of several steps including preloading the filter media in a pilot-scale model with copper and zinc by a load of n-1 years of the estimated service life (n). Subsequently, three representative rain events are simulated to evaluate the long-term performance by dissolved copper and zinc during the last year of application. The presented results, which verified the applicability of this method, were obtained for three filter channel systems and six filter shaft systems. The performance of the evaluated systems varied largely for both tested heavy metals and during all three simulated rain events. A validation of the pilot-scale assessment method with field measurements was also performed for two systems. Findings of this study suggest that this novel method does provide a standardized and accurate estimation of service intervals of decentralized treatment systems employing various filter materials. The method also provides regulatory authorities, designers, and operators with an objective basis for performance assessment and supports stormwater managers to make decisions for the installation of such decentralized treatment systems.

Sediments deposited on road surfaces are contaminated with pollutants; the load of pollution increases from coarse to fine particles. When it rains, different fractions of the road-deposited sediments are washed off depending on the rain intensity, the slope of the catchment, and other site-specific factors. This road runoff is often treated using settling processes implemented in different types of manufactured treatment devices. These devices can be tested with well-defined artificial test materials to determine the removal efficiencies of particulate matter in a reproducible manner. However, the suitability of the currently deployed artificial test materials to represent the settling behavior of real runoff particle collectives is largely unknown. In this study, a laboratory method to measure and compare the settling behavior of artificial and real particle collectives with a reproducible particle size composition was developed. The particle collectives were obtained from different road surfaces, fractionated into sieve classes, and then recomposed into a defined particle size distribution that represented the road runoff. The settling velocity was analyzed in a modified settling column setup under constant conditions. The resulting data form a cumulative curve of the settling velocities for both artificial and real particle collectives. The main result from this work is that the tested artificial material and the recomposed real particle collectives have comparable settling behaviors despite different losses on ignition and densities.

Biofiltration has proved to be a useful system to treat combined sewer overflow (CSO). The study presented uses numerical simulation to detect the critical operating conditions of the filter. The multi-component reactive transport module CW2D was used for the simulation study. Single-event simulations of lab-scale-column experiments with varying boundary conditions regarding the throttle outflow rate were carried out. For the calibration of the CW2D model measurement results of four experiments in two lab-scale columns were used. The model was validated by simulating four events of two further columns filled with the same filter material. These columns were operating with higher throttle outflow rates than the columns used for calibration. For ammonium (NH4-N) a good fit between measured and simulated data could be achieved. However, the comparison of simulated and measured effluent concentrations of nitrate (NO3-N) showed that there is a need for further investigations mainly due to the uncertainties in the degradation process during dry periods between the loadings.

The stormwater runoff and infiltration performance of permeable pavements has been systematically evaluated within an intensive monitoring program. The primary objective of the investigation was to generate a broad database, which enables the development of an advanced simulation module for urban drainage modelling. Over 160 field and lab scale experiments have been completed and analyzed for surface runoff and infiltration characteristics. The test series include several pavement types under various boundary conditions such as diverse precipitation impacts, varying surface slope and layer construction as well as different stages of surface clogging and several base and subgrade layer characteristics. The results represent a reliable and comprehensive database that allows profound conclusions and substantial recommendations.

A dataset of 294 monitored sites from six continents (Africa, Asia, Australia, Europe, North and South America) was compiled and evaluated to characterize the occurrence and fate of heavy metals in eight traffic area categories (parking lots, bridges, and three types each of both roads and highways). In addition, site-specific (fixed and climatic) and method-specific (related to sample collection, preparation, and analysis) factors that influence the results of the studies are summarized. These factors should be considered in site descriptions, conducting monitoring programs, and implementing a database for further research. Historical trends for Pb show a sharp decrease during recent decades, and the median total Pb concentrations of the 21st century for North America and Europe are approximately 15 μg/L. No historical trend is detected for Zn. Zn concentrations are very variable in traffic area runoff compared with other heavy metals because of its presence in galvanized structures and crumbs of car tire rubber. Heavy metal runoff concentrations of parking lots differ widely according to their use (e.g., employee, supermarket, rest areas for trucks). Bridge deck runoff can contain high Zn concentrations from safety fences and galvanizing elements. Roads with more than 5000 vehicles per day are often more polluted than highways because of other site-specific factors such as traffic signals. Four relevant heavy metals (Zn, Cu, Ni, and Cd) can occur in the dissolved phase. Knowledge of metal partitioning is important to optimize stormwater treatment strategies and prevent toxic effects to organisms in receiving waters.

The benefits of nationally coordinated schemes to manage the introduction of new stormwater quality improvement devices (SQIDs) have been acknowledged in various countries. This review compares the existing frameworks used in Australia, Austria, Germany, New Zealand, Switzerland, and the United States. The review describes the framework and structure of each system, and their individual components are presented. The Australian and New Zealand protocols have yet to be formally adopted and remain largely untested. The Australian and New Zealand protocols are compared with successfully established processes operating in Austria, Germany, Switzerland, and the United States. Adequate resourcing of administrative processes and having the technical capability to review test results were found to be a critical component of the successfully adopted certification schemes. Based on the level of success of the introduction of alternative certification systems, the most successful have been integrated into the formal legislative frameworks found in each country. The creation of a successful SQID certification pathway in Germany has been driven by the implementation of new fees on the release of stormwater from private property, with exemptions where stormwater is actively managed at source. The review presented in this paper may be of benefit to countries considering the development of their own SQID evaluation and verification protocols.

This is an investigation into possible changes to quantity and composition of sewage in the combined sewer system and the waste water treatment plant (WWTP) caused by new stormwater management strategies (mainly by disconnecting areas from the sewer system). Various scenarios were developed and the consequences on the water systems were calculated by using the simulation model KOSMO, in a fictional catchment. The results of the combined sewer overflow-calculation show an enormous decrease of the overflow annual load for different parameters (COD, ammonia) by the reduction of impervious surfaces. Thus, the overflow concentrations of some parameters increase dramatically under these conditions, in particular the ammonia concentration might cause critical situations (e.g. sensitive receiving water).

Selected organic pollutants are classified based on an intensive literature survey. Two wastewater parameters (COD and ammonium) and six selected organic pollutants (polycyclic aromatic hydrocarbons (PAH), diethylhexylphthalate (DEHP), estradiol (E2), ethinylestradiol (EE2), ethylenediamine tetraacetic acid (EDTA) and nitrilo triaceticacid (NTA)) are specified. As a result, for the first time representative concentrations in dry weather flow, surface runoff and effluent of wastewater treatment plants (WWTPs) in combined sewer systems (CSS) are stated. The second part of the paper presents a first estimation of main emission out of a combined sewer system and possible receiving water impacts in terms of (1) annual discharged loads calculated by pollution load simulations in a hypothetical catchment and (2) concentrations calculated in combined sewer overflows (CSO) discharges and resulting receiving water concentrations.

The EU Water Framework Directive (WFD) calls for a good quality of all water bodies. Retention soil filters (RSF) have been developed to treat discharges from combined sewers systems. RSF have proved over the past 15 years to be the most effective measure to meet the EU WFD standards, especially for small or particularly sensitive receiving waters, which require an enhanced reduction of emissions from combined sewer overflows (CSOs). The paper presents results from laboratory-scale experiments, in which the oxygen measurement in the filter plays a main role. The results show remarkable differences in oxygen concentrations in different filter depths. The highest oxygen consumption takes place in the upper part of the filter. In the lower part the re-aeration of sewage from the soil air dominates. This indicates that the biological activity is limited to the upper part of the filter. The availability of oxygen in the filter is a sign for degradation of wastewater compounds (ammonium, COD) under certain conditions and already takes place during the filter operation. The removal of ammonium especially cannot be strictly divided into phases of sorption during the loading and oxidation during the dry period any more.

Emissions of selected organic substances from a hypothetical combined sewer system are calculated by pollution load simulation. The results are subsequently discussed. First, representative concentrations of chemical oxygen demand (COD), ammonium (NH4-N) and eight selected organics (polycyclic aromatic hydrocarbons (PAH), isoproturone, Di(2-ethylhexyl)phthalate (DEHP), ibuprofen, 17-ß-estradiol (E2), 17-a-ethinylestradiol (EE2), ethyl-enediamine tetraacetic acid (EDTA), nitrilo triaceticacid (NTA)) in dry weather flow, surface runoff and effluent of WWTP in combined sewer systems are stated based on a literature survey. The second part of the paper presents pollution load simulations and first calculations of possible dis-tributions of organics in combined sewer systems for a hypothetical catchment. Different scenarios of annual discharge loads of main emission matrices of the catchment (waste water treatment plant (WWTP) effluent and combined sewer overflow (CSO)) are compared to determine significant dis-charge points. The results of the pollution load simulations show that generally discharges from the WWTP dominate the total emissions of combined sewer systems. Nevertheless, emissions from CSOs are not negligible in some cases (e.g. for estradiol). In summary, the results give first indications about possible strategies to reduce pollutant emissions from combined sewer systems. The paper also formulates recommendations for the selected organic compounds.

Alternatively to single combined sewer overflow (CSO) tanks, vortex separators can substitute small CSO tanks for urban drainage treatment in combined sewer systems. In spite of a smaller storage capacity compared to conventional CSO tanks, vortex separators show an increased removal efficiency of settleable solids. Additionally a combination of vortex separators subsequently followed by CSO tanks can be applied. Such a combined structure is the focal point of a monitoring program at the Institute of Environmental Engineering of University Kaiserslautern.

Considering different flow components of the urban drainage an enormous variety in quantities of important quality parameters (COD, ammonia, copper and lead) can be observed. This is due to different influence factors which are divided in objectives of the study and in influence factors concerning the investigation methodology and site specific conditions. An important chemical quality parameter in urban drainage is the COD. One advantage is the relatively easy determination which leads to a good data basis and provides a good transferability of data in different flow types. A disadvantage of COD and other sum parameters used in urban drainage monitoring programs is, that it is only to a minor extent possible to formulate statements about ecotoxic potential for receiving waters. Therefore recently alternative to the sum parameters other pollutant parameters have been discussed and are presented in this paper. Beside standard (waste water related) chemical organic parameters new lately discussed organic pollutants are listed and a first evaluation of an environmental potential is given. Groups of substances, like pesticides and nitrophenols, which are often found in surface runoff were taken into account as well as pollutants originating from dry weather flow, e.g. human medicines. Especially in the group of the endocrine disruptors certain substances (e.g. nonylphenol) are already listed in several environmental guidelines and also have a potential of occurrence in different flow types of the urban drainage system.