The main aim of this study was a survey of micropollutants in stormwater runoff of Berlin (Germany) and its dependence on land-use types. In a one-year monitoring program, event mean concentrations were measured for a set of 106 parameters, including 85 organic micropollutants (e.g., flame retardants, phthalates, pesticides/biocides, polycyclic aromatic hydrocarbons (PAH)), heavy metals and standard parameters. Monitoring points were selected in five catchments of different urban land-use types, and at one urban river. We detected 77 of the 106 parameters at least once in stormwater runoff of the investigated catchment types. On average, stormwater runoff contained a mix of 24 µg L⁻¹ organic micropollutants and 1.3 mg L⁻¹ heavy metals. For organic micropollutants, concentrations were highest in all catchments for the plasticizer diisodecyl phthalate. Concentrations of all but five parameters showed significant differences among the five land-use types. While major roads were the dominant source of traffic-related substances such as PAH, each of the other land-use types showed the highest concentrations for some substances (e.g., flame retardants in commercial area, pesticides in catchment dominated by one family homes). Comparison with environmental quality standards (EQS) for surface waters shows that 13 micropollutants in stormwater runoff and 8 micropollutants in the receiving river exceeded German quality standards for receiving surface waters during storm events, highlighting the relevance of stormwater inputs for urban surface waters.

A large variety of substances are used in building materials to improve their properties. In recent years, attention to organic additives used, for example, in renders, façade paints or roof sealing sheets has increased as these compounds have been detected in urban stormwater runoff and surface waters. In this paper, we show the extent of emissions induced by rain events in two study sites in Berlin. For this purpose, stormwater runoff from roofs, façades, and in storm sewers was sampled and analysed over a period of 1.5 years in two residential catchments. Results show that, in particular, the biocides diuron and terbutryn from façades, the root protection agents mecoprop and MCPA in bituminous sheeting, and zinc from roofs and façades reach concentrations in the stormwater sewer that exceed limit values for surface waters. Additionally, transformation products of the biocides were also detected. However, many other analysed substances were below the quantification limit or inconspicuous in their concentration levels. The emissions, modelled with the software COMLEAM, demonstrate that in urban areas the limit values in smaller surface waters are exceeded during wet weather. Furthermore, the orientation of the buildings to wind-driven rain is essential for the emitted load from façades. The calculated mass balances of both catchments show that a major portion of all substances remains on-site and infiltrates diffusely or in swales, while the remaining portion is discharged to stormwater sewers. For example, in one of the two study sites, <5% of diuron emissions are discharged to surface waters. Infiltration, in particular, is therefore a crucial pathway of pollution for soil and groundwater. Measures for source control are proposed to mitigate the leaching of environmentally relevant substances from construction materials.

Bank filtration schemes for the production of drinking water are increasingly affected by constituents such as sulphate and organic micropollutants (OMP) in the source water. Within the European project AquaNES, the combination of bank filtration followed by capillary nanofiltration (capNF) is being demonstrated as a potential solution for these challenges at pilot scale. As the bank filtration process reliably reduces total organic carbon and dissolved organic carbon (DOC), biopolymers, algae and particles, membrane fouling is reduced resulting in long term operational stability of capNF systems. Iron and manganese fouling could be reduced with the possibility of anoxic operation of capNF. With the newly developed membrane module HF-TNF a good retention of sulphate (67–71%), selected micropollutants (e.g., EDTA: 84–92%) and hardness (41–55%) was achieved together with further removal of DOC (82–87%). Fouling and scaling could be handled with a good cleaning concept with acid and caustic. With the combination of bank filtration and capNF a possibility for treatment of anoxic well water without further pre-treatment was demonstrated and retention of selected current water pollutants was shown.

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 has not been well known until now. In this study, the behavior of a full-scale (length: 45 m) reactive swale treating drainage water from 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 full-size field system is usually restricted to winter and spring months (December–May), it usually operates at low water temperatures of 5–10 °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%) for short residence times (<0.1 day), increasing to >25% at residence times >10 h (0.4 day). Performance was compared to results of two technical-scale reactive swales (length: 8 m) operated for 1.5 years with two different residence times (0.4 and 2.5 days), situated at a test site of the German Federal Environmental Agency in Berlin (Germany). Similar nitrate reduction was observed for comparable temperature and residence time, showing that up-scaling is a suitable approach to transferring knowledge gathered from technical-scale experiments to field conditions. For the design of new mitigation systems, one recommendation is to investigate carefully the expected inflow volumes in advance to ensure a sufficient residence time for effective nitrate reduction at low temperatures.