Im Rahmen einer etwa zweijährigen Studie wurde für Berlin erstmals das Ausmaß der Belastung von Regenabfluss mit Spurenstoffen durch ein einjähriges Monitoringprogramm in Einzugsgebieten unterschiedlicher Stadtstrukturtypen (Altbau, Neubau, Gewerbe, Einfamilienhäuser, Straßen) untersucht. Insgesamt wurden etwa 90 volumenproportionale Mischproben auf über 100 Spurenstoffe analysiert (zum Beispiel Phthalate, Pestizide/ Biozide, Flammschutzmittel, polycyclische aromatische Kohlenwasserstoffe, Schwermetalle), von denen ein Großteil (über 70) detektiert wurde. Die höchsten Konzentrationen an organischen Spurenstoffen wurden für Phthalate gefunden (DIDP - DINP: durchschnittlich über 12 µg/L), während Schwermetalle von Zink dominiert wurden (durchschnittlich 950 µg/L). Für die Mehrzahl der Stoffe gab es dabei signifikante Unterschiede zwischen den Stadtstrukturen. Für einige Substanzen (zum Beispiel DEHP, Carbendazim, einige polycyclische aromatische Kohlenwasserstoffe) wurden im Regenwasserabfluss Umweltqualitätsnormen (UQN) für Gewässer überschritten. Zusätzlich bei Regenwetter in einem Fließgewässer genommene Proben zeigen, dass es auch im Gewässer zur Überschreitung von zulässigen Höchstkonzentrationen (ZHK-UQN) bei Regen kommen kann. Eine Hochrechnung der über das Regenwasser in die Gewässer gelangenden Spurenstofffrachten für Gesamt-Berlin hat ergeben, dass etwa 1,5 Tonnen an organischen Spurenstoffen über Regenabfluss jährlich in die Berliner Gewässer gelangen. Ein Vergleich mit modellierten Frachten abwasserbürtiger Spurenstoffe, die über Kläranlagenablauf in die Berliner Gewässer gelangen, zeigt, dass Frachten regenwasserbürtiger Spurenstoffe in der gleichen Größenordnung wie schmutzwasserbürtige Spurenstoffe liegen können.

One way of coping with water shortness is through reusing wastewater. In order to enhance potable water production in sites dealing with water shortness, treated wastewater can be fed into an intermediate storage system, generally a natural water reservoir from which drinking water is produced. This procedure is called indirect potable reuse. Although this technique may be an innovative way of coping with water shortness, little is known about the effect of this procedure concerning environmental and human health. In order to find more about the environmental and health human risks arising from indirect potable reuse technologies a risk assessment was carried over in the French Department of Vendée. This site deals with water shortness from May to October through a significantly enhanced water consumption in the coastal aera of this department caused by the increase of tourism activities and intensified crop irrigation. To achieve this task 35 different organic micropollutants, in its majority pesticides and pharmaceuticals were studied. Therefore, a risk assessment on water reuse technologies was performed at the site of concern. Furthermore, the impact of two tertiary treatments developed within the framework of the European DEMOWARE project on minimising arising risks was also taken into account. Results showed that 16 substances present a potential risk to the environment and/or to human health at the WWTP effluent. Similar results were achieved in fresh water, in this case 14 compounds have a risk quotient higher than 1 indicating a risk for both, health and environment. Furthermore, outcomes from the tertiary treatments risk characterisation showed that none of the studied tertiary techniques is cappable of reducing environmental and health risks for all substances to acceptable levels (RQ < 1). Same results were achieved for the risk characterisation in fresh water.

This study aimed at characterizing the groundwater flow pattern in a semi-arid agricultural area in northern India crossed by an intermittent monsoon-controlled watercourse, the Najafgarh drain. More specifically, it focused on studying the impact of groundwater recharge from the riverbed to the regional aquifer using hydrogeochemical and isotopic data. Significant hydrogeochemical zonation was observed between the northern, central and southern sides of the drain, linked to different mineralization processes and mixings. Northward from the drain, groundwater was mainly brackish (4.1–23.4 mS/cm), due to dissolution of evaporites (halite and anhydrite). Southward from the drain, mostly fresh groundwater was found (from 0.5 to 2.3 mS/cm), revealing notable cation exchange processes. In the vicinity of the drain (central area), mineralization was intermediate (0.7–4 mS/cm) and groundwater showed low geochemical evolution, supposing a distinct origin. Stable isotopes of water (d18O, d2H) confirmed that central groundwater was not a simple mixing between northern and southern groundwater masses, but had a significant component of infiltrated surface water from the drain. Potentiometric data supported these findings and confirmed the contribution of the drain to the recharge of the aquifer, setting up a hydraulic barrier between north and south, despite surface water availability limited to the monsoon season and low hydraulic conductivity of the riverbed. This study demonstrates the value of the geochemical and isotopic analysis of groundwater to characterize groundwater flow pattern in peri-urban agricultural areas, especially surface water–groundwater interactions.

Nutrients, phosphorus and nitrogen, from municipal and industrial water streams contribute to the pollution or reduce the ecological potential of receiving water bodies. Recovering or reducing the nutrient content of waste streams, thus reducing the amounts of phosphorous and nitrogen that ends up in the water bodies, will contribute to a better environment. The first part of this report describes two tests performed to treat the concentrate of the reverse osmosis process at the Torreele facility. The first test used a natural system based on willows; the second test was based on post-denitrification MBBR. The willows proved able to remove nutrients for more than 30%, resulting in a substantial cost benefit for discharge which could make it economical feasible when installed at full-scale to treat the total volume of RO concentrate. Contrary to the willows, that even remove part of the nitrogen in winter, the post-denitrification MBBR was only efficient when N-NO3- exceeded 30 mg/L. The variable N-NO3- N-NO3- concentration and salinity of RO concentrate seemed to be limiting factors for a good performance. The second part of this report summarizes the activities regarding the optimization of water and nutrient (nitrogen and phosphorus) management at the reuse site Braunschweig, Germany. A detailed analysis of supply and demand of both, water and nutrients, for the reuse site was conducted. The optimization potential is especially high for nitrogen management, since the simultaneous supply via the Braunschweig wastewater treatment plant and additional conventional nitrogen fertilizer application by farmers result in an oversupply of nitrogen, losses to environment and a low efficient reuse compared to the total potential of renewable nitrogen in wastewater or sludge. Following this analysis, two possible solutions are discussed (fertigation and technical nutrient recovery), which are practically relevant for the Braunschweig reuse scheme in mid- and long-term timescale. Results indicate a high potential to increase the efficiency of nitrogen recycling. Simultaneously irrigation adopted on water demand of plants can be achieved.

This report describes different options for tertiary treatment of secondary effluent from municipal wastewater treatment plants for the purpose of water reuse. For each of the treatment trains, associated environmental impact (represented by energy demand and related global warming potential) and risk reduction potential (i.e. removal of chemical and microbial contaminants) are described based on the results of the DEMOWARE case studies. This should inform water professionals about impacts and benefits of different options for producing reclaimed water, enabling an informed decision on an adequate treatment train depending on the water quality targets for the respective reuse purpose.