Combined sewer systems are one of the major sources of microbiological contamination in urban water bodies. However, identification of hotspots for pathogen emissions is not straightforward, especially in large and complex drainage systems. To determine the relevance of different CSO outlets for bathing water quality a simple tracer approach which uses wastewater volume as a proxy for pathogen emissions has been developed and tested for the city of Berlin, Germany. The approach reveals that the average wastewater ratio in CSO varies largely between different river outlets (0 to 15%). Hence, the outlets with the largest CSO volumes are not automatically the greatest wastewater emitters and assumed hotspots for pathogen contamination do not coincide with hydraulic hotspots. This is verified with own measurements that show enormous differences in pathogen concentrations between waste and stormwater of 4 orders of magnitude. As a result, wastewater which represents only 5% of the CSO volume contributes > 99% of the pathogen loadings to the river. The study highlights the relevance of wastewater volumes for the identification of point sources for the hygienic impairment of water bodies.

Soil aquifer treatment (SAT) is one of the most promising water reclamation and storage techniques in water reuse. This document summarizes the experiences gained in two full scale sites (Shafdan and El Port de la Selva) focused on overcoming the barriers associated with this low-cost technology.

Swimming in urban surface waters is still an exception in European cities. At the same time there are numerous initiatives trying to achieve a quality of urban surface waters that allows recreational activities including swimming. In order to manage bathing waters properly the EU Bathing Water Directive (2006/7/EC) demands the elaboration of bathing water profiles in which sources of pollution have to be assessed. In order to investigate the relevance of stormwater as a source of microbial contamination as well as the influence of catchment characteristics on the faecal loading, E.Coli, intestinal Enterococci and colony counts have been measured in event related stormwater samples of three different catchment areas in Berlin. The catchment areas were chosen to be as homogeneous as possible representing catchments of old housing buildings (OLD), new housing buildings (NEW), and commercial areas (COM). N-Formylaminoantipyrine (FAA) was measured as a tracer for raw wastewater. Results showed elevated concentrations (1-2 log units) of faecal indicator organisms (FIO) in catchment OLD (104-105 in comparison to 103 cfu/100mL) suggesting illicit connections of wastewater discharges to rainwater drains, which is supported by elevated concentrations of FAA in the same catchment type. This underlines the relevance of these illicit connections as a source of hygienic contamination, which has to be considered when planning urban bathing water activities.

This report summarizes the results of Life Cycle Assessment, Water footprinting, and quantitative microbial and chemical risk assessment for selected demosites of water reuse in Europe, measuring the potential impacts of different types of water reuse on environment and human health. The case studies show that water reuse is often preferable from an environmental point of view in areas with water scarcity problems if compared to other alternatives such as water import or seawater desalination. Potential risks of water reuse for ecosystems or human health can be adequately managed if suitable processes for reclaimed water treatment are used and operated correctly. However, the study also shows the trade-offs between a higher level of reclaimed water treatment and increased environmental impacts from associated efforts in energy, chemicals and infrastructure. This inherent trade-off requires a site-specific assessment of reuse schemes to choose an adequate treatment scheme for risk management with reasonable global environmental impacts.

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.

This report presents the assessment of the planned water reuse scheme at Le Jaunay reservoir (Vendée) in its potential risks for human health and ecosystems, and also in its overall environmental impacts. Methods of risk assessment (quantitative microbial and chemical risk assessment) and Life Cycle Assessment are used to characterize the potential hazards associated with the use of reclaimed water, but also the environmental benefits compared to other options for additional drinking water supply. The assessments show that water reuse can be operated without unacceptable risks for humans and the environment, and that it is competitive to other options of water supply in its energy demand and greenhouse gas emissions. Data quality should be improved in a demonstrator phase to validate the outcomes of this first assessment.

The practice of using the wastewater of the city of Braunschweig for irrigation on the surface areas of the Braunschweig Wastewater Association, over decades, starting in 1954, has changed from being a disposal of raw wastewater to a sprinkle irrigation of biologically treated wastewater including the use of the nutrients from sewage sludge. Future requirements on the disinfection of wastewater and also the expansion of agricultural crop growing portfolios could require the installation of a wastewater disinfection system. For this various processes have been tested in pilot trials. Generally, UV disinfection with long project run times and high average usage of the processing capacity are advantageous whereas short project run times or a lower utilisation of the maximum capacity rather favour a dosing of performic acid. A near-natural secondary treatment on the other hand proved itself to be not reliable enough.

In recent years several ways of recovering phosphorous from municipal wastewater have been developed. Depending on the applied technology the recovered products as well as the quality of sewage sludge vary significantly concerning the concentrations of heavy metals and organic residues. Within WA 4 “environmental, economic and risk assessment of P recovery options” of the P-REX project a quantitative risk assessment of substances in phosphorus products for humans and environment is intended. In this deliverable risk assessment is done as a relative risk ranking for PCDD/F, dl-PCB, PAH, As, Cd, Cr, Cu, Hg, Ni, Pb and Zn between seven secondary phosphate fertilizers from wastewater stream, sewage sludge, mono-incinerated ash from sewage treatment and conventional phosphorus fertilizers.

This report provides the reader with an overview of assessment methodologies used within DEMOWARE and the specific features when using QMRA, QCRA, LCA, and WFP approach for the assessment of water reuse systems. For the actual application of LCA and water footprint databases and assessment software is needed. Therefore, three complementing goals shall be achieved: (i) to provide practitioners with the principles, methods and limitations of QMRA, QCRA, LCA and WFP (ii) to provide LCA, WFP, RA practitioners with additional information when using the respective method for the assessment of water reuse systems. For QMRA a summary of guidelines and default values is collected from different guidelines documents (WHO, Australia, US-EPA), which allow a first simplified and thus user friendly risk estimate.