The Berliner Wasserbetriebe are the largest water supply and wastewater disposal company in Germany. They are challenged to tackle various kinds of odour problems emerging from the sewer network. The continuous extension of sewer networks and a decrease in water consumption (in Berlin: ~ 20 % in the last 16 years, according to the statistical office BB, 2009) have led to elevated odour emissions arising from sewer systems. Together with growing public concern over odours from water treatment works, this has led to increasing numbers of odour complaints in urban catchments (Stuetz and Frechen, 2001; ATV-DVWK-M 154, 2003; Barjenbruch, 2003). Different odour abatement technologies are widely-used but often response only after consumer complaints and do not consider adequate identification of odour problems beforehand. An operational, together with a scientific approach is necessary in order to apply effective measures or combinations thereof. In Berlin annually almost 3 Mio € are spent by BWB to reduce odour emissions from the Berlin sewer system (BWB, 2006). Applied measures vary from dosing of nitrate or iron hydroxide sludge, flushing, or compensation by means of bio-filters or masking. The quantification of odour by means of continuous odour monitoring solutions such as electronic noses can contribute to minder economic and operational risks in odour management. The paper presents the research project ODOCO-ARTNOSE, dealing with the evaluation of electronic noses for the online application in sewer systems. The KompetenzZentrum Wasser Berlin (research centre) in cooperation with the Berlin water utilities Berliner Wasserbetriebe and Veolia Water will carry out bench tests with selected, commercially available chemosensor arrays to identify advanced applications of electronic noses in odour management in sewer networks. Objectives of the project are to analytically assess the online-ability of electronic noses by means of a multi-criteria methodology and to specify future odour control services based on the application of e-noses in sewer networks. The potential of electronic noses will be evaluated as tool to fulfil certain needs, namely (i) support for planning/designing of odour preventive measures and abatement strategies, (ii) support for real-time odour control and (iii) data acquisition tool to supervise and document (industrial) dischargers, document the effect of abatement measures and document legal compliance. Tests are possible to be carried out in the frame of a sewer research plant or within the sewer system of Berlin. A large-scale research plant was developed by Berliner Wasserbetriebe for investigating different odour and corrosion strategies. The plant consists of 2 independent gravity lines and is fed by combined wastewater from Berlin, pumped directly from the sewer. Various milieu conditions can be generated. The paper places current challenges within the city of Berlin into perspective and displays examples of odour abatement strategies of Berliner Wasserbetriebe. Expected outcomes and correlated benefits of the project will be presented. The methodological approach relies on a transparent selection of chemosensor array systems, on bench tests following a sophisticated measurement program and the evaluation of the electronic noses by clear defined criteria.

The Berliner Wasserbetriebe are the largest water supply and wastewater disposal company in Germany. They are challenged to tackle various kinds of odour problems emerging from the sewer network. The continuous extension of sewer networks and a decrease in water consumption (in Berlin: ~ 20 % in the last 16 years, according to the statistical office BB, 2009) have led to elevated odour emissions arising from sewer systems. Together with growing public concern over odours from water treatment works, this has led to increasing numbers of odour complaints in urban catchments (Stuetz and Frechen, 2001; ATV-DVWK-M 154, 2003; Barjenbruch, 2003). Different odour abatement technologies are widely-used but often response only after consumer complaints and do not consider adequate identification of odour problems beforehand. An operational, together with a scientific approach is necessary in order to apply effective measures or combinations thereof. In Berlin annually almost 3 Mio € are spent by BWB to reduce odour emissions from the Berlin sewer system (BWB, 2006). Applied measures vary from dosing of nitrate or iron hydroxide sludge, flushing, or compensation by means of bio-filters or masking. The quantification of odour by means of continuous odour monitoring solutions such as electronic noses can contribute to minder economic and operational risks in odour management. The paper presents the research project ODOCO-ARTNOSE, dealing with the evaluation of electronic noses for the online application in sewer systems. The KompetenzZentrum Wasser Berlin (research centre) in cooperation with the Berlin water utilities Berliner Wasserbetriebe and Veolia Water will carry out bench tests with selected, commercially available chemosensor arrays to identify advanced applications of electronic noses in odour management in sewer networks. Objectives of the project are to analytically assess the online-ability of electronic noses by means of a multi-criteria methodology and to specify future odour control services based on the application of e-noses in sewer networks. The potential of electronic noses will be evaluated as tool to fulfil certain needs, namely (i) support for planning/designing of odour preventive measures and abatement strategies, (ii) support for real-time odour control and (iii) data acquisition tool to supervise and document (industrial) dischargers, document the effect of abatement measures and document legal compliance. Tests are possible to be carried out in the frame of a sewer research plant or within the sewer system of Berlin. A large-scale research plant was developed by Berliner Wasserbetriebe for investigating different odour and corrosion strategies. The plant consists of 2 independent gravity lines and is fed by combined wastewater from Berlin, pumped directly from the sewer. Various milieu conditions can be generated. The paper places current challenges within the city of Berlin into perspective and displays examples of odour abatement strategies of Berliner Wasserbetriebe. Expected outcomes and correlated benefits of the project will be presented. The methodological approach relies on a transparent selection of chemosensor array systems, on bench tests following a sophisticated measurement program and the evaluation of the electronic noses by clear defined criteria.

The study aims at validating the point-of-use investigations on long-term gravity-driven ultrafiltration for a scaled-up system, which could produce drinking water for a community of 100-200 inhabitants using natural surface water. Eawag, KWB and Opalium conceived a membrane-based small-scale system (SSS) which can operate without crossflow, backflush, aeration or chemical cleaning. Equipped with a biosand filter as pre-treatment (not used in South Africa), it is designed to be robust, energy-sufficient (gravity-driven) and run with restricted chemical intervention (only residual chlorine). The containerised unit (10’) requires to be fed with raw water at a 2 m-height (energy-equivalent to <8 Wh/m3). As sole operational requirement, the membrane reactor is to be drained (i.e. emptied) on daily to weekly basis to superficially remove the material retained by the membrane and accumulated in the module. Otherwise, the system, which is only driven by a 40 cm differential pressure head (i.e. 40 mbar), is totally self-determined and autonomous. This report details the validation tests performed at Ogunjini in the region of Durban (South Africa) from February to April 2010: the gravity-driven UF compact unit showed promising results in regards to flux stabilization and flow capacity. The unit was operated in South Africa with Ogunjini surface water and was run with restricted chemical intervention or maintenance (no backflush, no aeration, no crossflow and no chemical). Under South African environmental conditions and with direct filtration of the river water and only one manual drainage of the membrane reactor every weekday, the unit could fulfill the design specification in terms of water production (5 m3/d) as long as the turbidity of the raw water remained in a reasonable level (up to 160 NTU), with a filtration flux typically around 4 to 6 L/h.m² (corrected to 20°C). This value was in the same range as the lab results and was consistent with the first phase results (around 5-7 L/h.m² after biosand filtration). However, the flux dropped significantly to a range of 2 to 4 L/h.m² after a rain event resulting in a turbidity peak over several days up to > 600 NTU. This demonstrated that for variable raw water types with expected turbidity peaks above 100 NTU, a pre-treatment would be required for the system (biosand filter or other). The performance of microbiological tests confirmed the integrity of the membrane and the ability of the system to achieve complete disinfection.

This report presented recent developments in the field on the UV-LED disinfection. This technological field is very recent and further interests - along with rapid and continuing improvements in performance (especially in terms of emission power) - are expected within the next years. After the physical characterisation of the few UV-LEDs - at 269 and 282 nm - that are currently available on the market, their disinfecting action was to be measured via biodosimetric tests. They show an increase of the inactivationwith an increasing fluence using different types of raw water, although some early static tests tend to highlight potential recontamination and inhomogeneous distribution of UV-light - which may be explained by the module configuration. Main other results indicate that UV-absorbing compounds in the various waters reduce the disinfection capacity. Morevoer, a more effective disinfection is observed at 269 nm than at 282 nm for a similar fluence. However, the emission output is better with 282 nm - UV-LEDs. Therefore, an interesting aspect, worth being investigated in the future is to ensure an optimized configuration, which balances the input power, which is necessay to run the UV-LED module, and its disinfecting action. With potential enhanced emission powers, new developments for UV-LED water purification applications would enable to perform larger-scale tests and shorten UV exposure times.

The present study examines the contribution of combined sewer overflows (CSO) to loads and concentrations of trace contaminants in receiving surface water. A simple method to assess the ratio of CSO to wastewater treatment plant (WWTP) effluents was applied to the urban River Spree in Berlin, Germany. The assessment indicated that annual loads are dominated by CSO for substances with removal in WWTP above w95%. Moreover, it showed that substances with high removal in WWTP can lead to concentration peaks in the river during CSO events. The calculated results could be verified based on eight years of monitoring data from the River Spree, collected between 2000 and 2007. Substances that are well removed in WWTP such as NTA (nitrilotriacetic acid) were found to occur in significantly increased concentration during CSO, while the concentration of substances that are poorly removable in WWTP such as EDTA (ethylenediaminetetraacetic acid) decreased in CSO-influenced samples due to dilution effects. The overall results indicate the potential importance of the CSO pathway of well-removable sewage-based trace contaminants to rivers. In particular, high concentrations during CSO events may be relevant for aquatic organisms. Given the results, it is suggested to include well-removable, sewage-based trace contaminants, a substance group often neglected in the past, in future studies on urban rivers in case of combined sewer systems. The presented methodology is suggested for a first assessment, since it is based solely on urban drainage data, which is available in most cities.

The effect of combined sewer overflow (CSO) control measures should be validated during operation based on monitoring of CSO activity and subsequent comparison with (legal) requirements. However, most CSO monitoring programs have been started only recently and therefore no long-term data is available for reliable efficiency control. A method is proposed that focuses on rainfall data for evaluating the effectiveness of CSO control measures. It is applicable if a sufficient time-series of rainfall data and a limited set of data on CSO discharges are available. The method is demonstrated for four catchments of the Berlin combined sewer system. The analysis of the 2000-2007 data shows the effect of CSO control measures, such as activation of in-pipe storage capacities within the Berlin system. The catchment, where measures are fully implemented shows less than 40 % of the CSO activity of those catchments, where measures have not yet or not yet completely been realised.

A mixed surface and sub-surface flow riparian zone in Brittany (France), which is mainly fed by water from drainage ditches, was monitored for nitrate retention over three years from 2005 to 2007. Results show high time-averaged nitrate retention of >90 % for subsurface and ~70 % for surface passage. However, no retention could be detected during major rain events, which reduced the overall (flow-averaged) retention to ~40 %. Based on the findings, higher nitrate retention can be reached by increasing (i) the water residence time in buffer systems, (ii) the fraction of subsurface passage or (iii) denitrification rates in the system. (i) is only feasible if (active) buffer volume is enlarged, which may be difficult in practice. In the case of Brittany an enlargement can also be reached by extending buffer systems into existing drainage ditches. (ii) is of particular importance in areas with low soil permeability. In such areas, addition of gravel or sand beds can be considered. Regarding (iii), denitrification turns maximal under anaerobic conditions if sufficient carbon sources are available. In straw- and bark-filled column experiments we found high nitrate retention rates of >99 % and ~40 %, respectively, during a comparably low residence time of ~5 hours. As a result, the addition of external carbon sources to buffer systems is suggested. Currently, several pilot sites are constructed in the Ic watershed in Brittany attempting to take into account points (i) to (iii). For the following four buffer types, monitoring will start in February 2010: (a) two short drainage ditches, filled with carbon sources, (b) one drainage ditch and (c) one riparian wetland, each filled with a gravel filter, and optional upstream addition of carbon sources.

The present study aims at developing a universal method for the localization of critical source areas (CSAs) of diffuse NO3- pollution in rural catchments with low data availability. Based on existing methods land use, soil, slope, riparian buffer strips and distance to surface waters were identified as the most relevant indicator parameters for diffuse agricultural NO3-pollution. The five parameters are averaged in a GIS-overlay to localize areas with low, medium and high risk of NO3- pollution. A first application of the GIS approach to the Ic catchment in France, shows that identified CSAs are in good agreement with results from river monitoring and numerical modelling. Additionally, the GIS approach showed low sensitivity to single parameters, which makes it robust to varying data availability. As a result, the tested GIS-approach provides a promising, easy-to-use CSA identification concept, applicable for a wide range of rural catchments.