Diffuse nitrate (NO3) contamination from intense agriculture adversely impacts freshwater ecosystems, and can also result in nitrate concentrations exceeding limits set in drinking water regulation, when receiving surface waters are used for drinking water production. Implementation of near-natural mitigation zones such as reactive swales or wetlands have been proven to be promising measures to reduce nitrate loads in agricultural drainage waters. However, the behavior of these systems at low temperatures and its dependence on system design is not well known until now. In this study, the behavior of a full scale (length: 45 m) reactive swale treating drainage water of an agricultural watershed in Brittany (France) with high nitrate concentrations in the receiving river, was monitored for one season (6 months). As flow in this field scale system is usually restricted to winter and spring months (December – May), it usually operates at low water temperatures of 5°C - 10°C. Tracer tests revealed shorter than designed retention times due to high inflows and preferential flow in the swale. Results show a correlation between residence time and nitrate reduction with low removal (<10%) at short residence times (<0.1 d), increasing to >25% at residence times >10h (0.4 d). Performance was compared to results of two technical scale reactive swales (length: 8 m) operated for 1.5 years at two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency (UBA) in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and residence time, showing that up-scaling is a suitable approach to transfer knowledge gathered from technical scale experiments to field conditions. For the design of new mitigation systems, one recommendation is to investigate carefully expected inflow volumes in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.

In recent years, organic micropollutants have been detected in urban storm runoff in several European studies. As rain water runoff in Berlin and other German and European cities is often discharged untreated in separated sewer systems, urban stormwater is a large potential source of micropollutants affecting receiving surface waters. As a consequence, it is important to know the local extent of the issue to be able to evaluate potential measures. In this study, a one year monitoring programme is conducted in the city of Berlin to estimate yearly loads of micropollutants from urban stormwater entering Berlin surface waters. Five different catchment types typical for Berlin were determined after analysis of GIS data (old building areas <1930, newer building areas >1950, single houses with gardens, roads and commercial areas) and monitoring points were selected fulfilling a number of criteria (including representativeness of catchment type, accessibility, sufficient flow, manhole size). Samples are taken using automatic samplers and a sampling strategy was developed to obtain best possible representative composite samples representing the average concentration of the sampled storm event. Results will then be used with measured flow data to calculate micropollutant loads of individual catchment types. A runoff model for Berlin applied to the individual catchment types and coupled with pollutant concentration relationships will be used to extrapolate results to city scale.

Diffuse nitrate (NO3-) contamination from intense agriculture adversely impacts freshwater ecosystems, and can also pose a risk to human health if receiving surface waters are used for drinking water production. Implementation of near-natural mitigation zones such as reactive swales or wetlands have been proven to be promising measures to reduce nitrate loads in agricultural drainage waters. However, the behaviour of these systems at low temperatures and its dependence on system design is not well known until now. In this part of the Aquisafe project, the behaviour of a full scale (length: 45 m) infiltration ditch and two parallel wetlands (surface flow wetland and infiltration wetland) treating drainage water of two agricultural watersheds in Brittany (France) with high nitrate concentrations in the receiving river, were constructed and monitored for 3 flow seasons in 2011, 2012 and 2013 to evaluate field scale performance of these systems. As the flow in both sites is usually restricted to winter and spring months (December – May), systems usually operate at low water temperatures of 5°C - 10°C. Tracer tests revealed shorter than designed retention times (average values for whole flow season 2013: 1.1 h for infiltration ditch, 4.3 h for infiltration wetland and 8.4 h for surface wetland) due to high inflows and preferential flow. This likely is the main reason for observed low average retention of nitrate loads of 1.5-3% during the whole flow season. However, increase of relative nitrate retention to up to 80% during low flow conditions at the end of flow season in May with higher HRT and increasing temperatures show that investigated systems generally work. Results show a stronger correlation between residence time and nitrate reduction for all three systems compared to correlation with temperature. Retention times necessary in existing systems to achieve nitrate retention >30% were 1 day for infiltration ditch and 3 days for wetlands. Performance was compared to results of two technical scale reactive swales (length: 8 m) operated for 1.5 years at two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency (UBA) in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and HRT values (during low flow conditions at end of flow season 2013), showing that up-scaling is a suitable approach to transfer knowledge gathered from technical scale experiments to field conditions. For the design of new mitigation systems, expected inflow volumes have to be investigated carefully in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.

According to the European Water Framework Directive, ‘good ecological and chemical status’ must be achieved for all surface waters by 2015 (European Parliament, 2000). Therefore, it is important to extend knowledge on pollutants that run off with urban rainwater. This study has the objective to determine which micropollutants occur in Berlin’s urban rain water run-off and how the most detrimental pollutants can be managed in a sustainable manner to reduce their impact on receiving waters. To reach these objectives, five catchments with different land use characteristics that together represent Berlin were selected for the collection of rainwater samples. These catchments consisted of New buildings (New), Old buildings (Old), One family homes (Ofh), Commercial buildings (Com) and Streets (Str). Actual sampling was done by installing an automated water sampler at each location, together with a flow measuring device to start the sampler during rain events. The following number of rain events were sampled and analysed; New (n=8), Old (n=7), Ofh (n=6), Com (n=11) and Str (n=4). Samples collected during rain events were processed to one volume proportional composite sample that represents the entire event. This sample was then analysed on the presence and concentration of micropollutants. With that information, measures where determined that can be applied for the reduction of pollutant loads. Micropollutants from the following groups were found during this study; pesticides / biocides, industrial chemicals, PAH’s, heavy metals, tracers, flame retardants and phthalates. From these groups, the most detrimental are; Nickel, Diuron, Isoproturon, Cadmium, Lead, PFOA, PFOS , polycyclic aromatic hydrocarbons (PAH), Nonylphenol, DEHP, Zinc, Copper, TCPP, Mecoprop, Glyphosphat, OHBT and Di-iso-decylphthalat. To assess measures for micropollutant reduction, the concept of source-path-threatened object was used to identify where pollutants come from and what pathway they follow to which vulnerable objects. Possible measures to reduce the load of these substances are banning or substituting the pollutant by legislation. Furthermore, vegetation infrastructure, decentralized pre-treatment, infiltration and sedimentation can be applied for reduction of pollutant loads. These measures should be applied in an integrated manner to enhance one another. Pollutant characteristics -and thus behaviour in the environment- is one of the most relevant criteria for the selection of measures to reduce these substances. The most effective approaches for particle and non-particle bound pollutants are end-of-pipe solutions. These consist of sedimentation systems for particle bound, and infiltration structures for non-particle bound micropollutants. Emitting sources (e.g. traffic) and paths (e.g. air) that contribute to pollutants in urban rainwater run-off are further relevant criteria. These can only be directly reduced by legislation, vegetation infrastructure can however be applied to reduce the mobility of these pollutants.

Der Regenwasserabfluss von versiegelten Flächen kann zu erheblichen Beeinträchtigungen von Flüssen und Seen führen. Durch das schnelle Ableiten des Regenwassers bleibt das positive Potenzial für die Stadtbevölkerung und die Umwelt zudem oft ungenutzt. Für eine nachhaltige Regenwasserbewirtschaftung stehen eine Vielzahl von Maßnahmen auf Gebäude-, Quartiers- und Kanaleinzugsgebietsebene zur Verfügung. Im laufenden BMBF-Projekt KURAS werden diese Maßnahmen hinsichtlich Ihrer stadträumlichen, klimatischen, ökologischen und ökonomischen Effekte umfassend untersucht. Daraus werden Empfehlungen für Planer und Behörden für den Umgang mit Regenwasser im städtischen Raum abgeleitet. Beispielhaft für den verfolgten Bewertungsansatz werden im vorliegenden Beitrag Indikatoren vorgestellt, mit denen die Maßnahmeneffekte auf drei ausgewählte Wirkungsbereiche (Biodiversität, Grundwasser und Oberflächengewässer) quantifiziert werden können. Erste Ergebnisse zeigen bereits, wie unterschiedlich Maßnahmen wirken können und wie wichtig die Berücksichtigung lokaler Schutz- und Entwicklungsziele bei der Maßnahmenauswahl ist. Aus der starken Streuung einzelner Bewertungsindikatoren kann zudem ein bedeutender Einfluss von Standortfaktoren und der konkreten Umsetzung einer Maßnahme abgeleitet werden, der bei der Planung ebenfalls berücksichtigt werden sollte.

Zum Erzielen guter Erträge in der Landwirtschaft und in Ermangelung nennenswerter fossiler Vorkommen müssen alljährlich ca. 1 Million Tonnen mineralisch gebundenen Phosphors nach Europa importiert werden. Gleichzeitig werden Rückgewinnungs- und Recyclingpotentiale dieser lebenswichtigen Ressource nicht bzw. wie im Falle des Klärschlamms nur zu einem geringen Anteil genutzt. In den letzten Jahren wurden zahlreiche technische Verfahren entwickelt, die dazu beitragen sollen, den Nährstoff Phosphor alternativ zur umstrittenen Praxis der Klärschlammausbringung wieder für die Landwirtschaft verfügbar und nutzbar zu machen. Insbesondere praxisnahe Lösungen haben bereits den Sprung in die großtechnische Umsetzung geschafft bzw. stehen kurz davor. Nationale wie internationale Initiativen widmen sich dem Zusammenbringen von Akteuren aus Wissenschaft, Politik und Wirtschaft, um die Implementierung voranzubringen. Für ein Nährstoffrecycling genügt es nicht, bei der Nährstoffrückgewinnung aufzuhören. To sustain good harvests, about one million tons of mineral phosphorus have to be imported to Europe annually, while the potentials to recover and recycle this essential resource remain untapped or are just inefficiently used as in the case of sewage sludge. In the recent years various technical alternatives to the traditional but disputed application of sludge in agriculture have been developed to recover the nutrient. Especially user friendly solutions have already made their way to full-scale or at least pilotscale application. National and international initiatives are dedicated to bridge the gaps between the relevant sectors of science, policy and industry to finally foster wide-spread implementation of phosphorus recovery and recycling. It is not enough to just recover nutrients. To achieve real recycling, the gap between recovery and return of phosphorus into the nutrient cycle needs to be closed. The supply side needs to match with the requirements of the demand side.

Durch das EU-Forschungsprojekt P-REX soll die Implementierung und Verbreitung technischer Phosphorrückgewinnungsverfahren vorangetrieben werden. Langfristiges Ziel ist die EU-weite Umsetzung von effektiver und nachhaltiger Phosphorrückgewinnung und Recycling aus dem Abwasserpfad, wobei regionale Bedingungen und Bedarfe berücksichtigt werden sollen. Bei den Phosphor-Rückgewinnungsverfahren wird der Phosphor in den meisten Fällen mittels chemischer beziehungsweise biologischer Eliminationstechniken zunächst in eine feste Phase, den Klärschlamm, überführt. Hierbei kommt es zu einer deutlichen Aufkonzentration des Phosphors. Dies ist für die Effizienz einer anschließenden Rückgewinnung entscheidend. Unterschieden werden können zunächst Verfahren, die den Phosphor aus dem Klärschlamm zurückgewinnen, und Verfahren, die den Phosphor aus der Asche im Anschluss an die Monoverbrennung zurückgewinnen. Bei der Rückgewinnung aus Klärschlamm kann zwischen den Verfahren mit direkter P-Fällung und den Verfahren mit chemischer Rücklösung und anschließender P-Fällung unterschieden werden. Bei der Rückgewinnung aus Klärschlammaschen kann zwischen nasschemischen Aufschluss-/Leachingverfahren und thermochemischen Verfahren unterschieden werden. In diesem Beitrag werden die verschiedenen Rückgewinnungsverfahren mit den wichtigsten Verfahrensansätzen und Prozessschritten vorgestellt und bewertet.

Energy and resource recovery from raw municipal wastewater is a pre-requisite for an efficient and sustainable wastewater treatment in the future. This paper evaluates several processes for upgrading existing wastewater treatment plants or new concepts towards energy positive and resource efficient wastewater treatment in their life-cyle impacts on the energy balance. In addition, future challenges for integrating both energy and resource recovery in wastewater treatment schemes are identified and discussed.

This report compiles the results of three consecutive work packages that have been worked on during the Aquisafe II project. The approach developed is based on the previous Aquisafe I project where the Soil Water Assessment Tool (SWAT) was used as an analytical instrument to develop mitigation strategies for N loads and concentrations in the Ic catchment. During Aquisage I we concluded that SWAT should include a wetland function with which the effect of artificially, constructed wetlands on solute N fluxes can be evaluated. Chapter 1 compiles results of an extensive literature review that was made to identify potential wetland routines and processes that can be included in SWAT. The SWAT add-on to be developed should allow to individually test the effect on single wetlands (e.g. in a given hydrological response unit or subcatchment) as well as the effect of multiple wetlands on the landscape scale. We therefore implemented a stand alone version of the new wetland module which is described in Chapter 2. Here we show the general functionality and individual components of the wetland module. The chapter ends with a virtual application of the modules using SWAT outputs copied from the Ic results. Additionally, a Monte Carlo based sensitivity analyses of the wetland module input parameters showed that the denitrification rate seems to be the most constrained parameter for the simulation of N turnover in the new wetland module. A full implementation of the new wetland module is described in chapter 3. Here, the structural embedment of the wetland module in the SWAT architecture is described. To proof the functionality of the SWAT wetland module model runs were compared to the stand alone version to make sure that the module was correctly implemented. We conclude that the SWAT wetland extension is ready to be tested in real world catchments. Such a full test of the SWAT wetland model was planned towards the end of Aquisafe II. However, as data from the wetlands constructed within Aquisafe II were not available in due time, this last test of the SWAT module was possible.