Die Umfrage des DVGW wurde Anfang 2009 in Zusammenarbeit mit dem Kompetenzzentrum Wasser Berlin gGmbH (KWB) durchgeführt. Der Fragebogen mit insgesamt 16 Fragen (-> Anhang A) zielt darauf ab, einen bundesweiten Überblick zum Brunnenbetrieb und unterschiedlichen Instandhaltungsmaßnahmen derjenigen Wasserversorger zu erhalten, die eigene Brunnen betreiben. Die vorliegende Auswertung wurde am Kompetenzzentrum Wasser Berlin durchgeführt. Nicht enthalten sind die vier ersten Fragen mit den allgemeinen Angaben des beantwortenden Unternehmens und einer Frage zum Thema Energieeffizienz (Seite 1 des Umfragebogens). Diese wurden durch den DVGW selbst ausgewertet (vgl. Plath and Wichmann 2009). Der brunnenbezogene Teil (Seiten 2 und 3) enthielt die vier Themenkomplexe: (1) Stammdaten (Fragen 5 bis 7) Es wurden die absolute Anzahl der in Betrieb befindlichen Brunnen und ihr durchschnittliches Alter erfragt. Diese Fragen dienen der Klassifizierung und Auswertung. Den Brunnenneubau betreffend, wurde eine Angabe zur Budgetplanung erbeten, um die folgenden Fragen zu Brunnenzustand, Alterung und Regenerierung in Bezug zum Neubau setzen zu können. (2) Brunnenbetrieb, Brunnenzustand und Alterung (Fragen 8 bis 11). Zum Brunnenbetrieb wurden die Art der Brunnensteuerung und die während des Betriebes erfassten Daten und Intervalle zur Betriebsüberwachung abgefragt, ebenso die Methoden und Intervalle zur Brunnenzustandsermittlung. (3) Brunnenregenerierung (Fragen 12 bis 14) Die Fragen zur Notwendigkeit, Veranlassung und Erfolgsbemessung von Regenerierungen dienen der Charakterisierung der Instandhaltungsstrategie. (4) Betriebsstrategie (Fragen 15 und 16) Abschließend wurde nach der Betriebsstrategie und einer möglichen Einflussnahme auf die Brunnenalterung durch Änderungen im Betrieb gefragt. Ziel der Auswertung ist es, den Stand der Praxis der Betriebsführung von Brunnen zu erarbeiten. Durch die gekoppelte Auswertung aller vier Themenkomplexe kann weiterhin geprüft werden, inwiefern die festgestellten Betriebs- und Instandhaltungsstrategien von der Größe des Betreibers oder der Altersstruktur der Brunnen abhängen. Durch den Vergleich der erarbeiteten Ergebnisse mit den in DVGW-Arbeitsblatt W125 (DVGW 2004) festgehaltenen Empfehlungen Forschungskann Raum für Verbesserungen, wie z.B. oder Weiterbildungsbedarf identifiziert werden. Gleichzeitig bietet die bundesweite Ermittlung Gelegenheit zur Einordnung des eigenen Standes der Praxis für die einzelnen Betreiber.

The impact of a pre-treatment by pre-ozonation (2-10 mg O3/L) and subsequent coagulation (FeCl3: 2-6 mg Fe3+/L) on the performance of a polymeric ultrafiltration membrane was studied. No free dissolved ozone was in contact with the membrane. Lab tests were performed using Amicon test cells fed with secondary effluent and the flux decline during filtration tests was measured. Flux decline was reduced with increasing coagulant concentration as well as with increasing ozone dosage. This effect was confirmed by a reduction in the amount of biopolymers measured with size exclusion chromatography by organic carbon detection (LC-OCD). Conducted multi filtration cycles revealed a significant increase in irreversible fouling after pre-ozonation that might be caused by increasing colloidal iron concentrations. Phosphorus in the permeate was successfully reduced to concentrations < 60 µg/L

Die EU-Wasserrahmenrichtlinie (2000) verlangt bis zum Jahre 2015 für alle europäischen Gewässer die Wiederherstellung eines „guten ökologischen Zustands“. In Berlin muss zur Erfüllung dieses Ziels insbesondere der Phosphoreintrag aus Kläranlagen minimiert werden, da Phosphor als limitierender Nährstoff für die Eutrophierung der Gewässer hauptverantwortlich ist. Vor diesem Hintergrund wird die Einführung einer Membranfiltrationsstufe mit vorgeschalteter Phosphatfällung in der Berliner Kläranlage Ruhleben diskutiert (Gnirß 2008). Das Jahresmittel der Phosphorkonzentration im Ablauf der Kläranlage Ruhleben beträgt 0,3 - 0,4 mg P/L. Der Zielwert für die weitergehende Behandlung des Klarlaufes wurde mit 0,05 - 0,1 mg P/L festgelegt. Die Filtration von Klärwerksabläufen mit Niederdruckmembranen bietet in Kombination mit einer Flockungsstufe eine wirkungsvolle Möglichkeit für das Erreichen niedriger Phosphorkonzentrationen und einer zusätzlichen Entfernung von Pathogenen. Das Hauptproblem beim Betrieb von Niederdruckmembranen stellt jedoch nach wie vor der durch Fouling auftretende Verlust der Filtrationsleistung dar. Dieser entsteht durch das Verblocken der Membranporen mit organischem Material sowie Kuchenbildung auf der Membranoberfläche und schlägt sich entweder in der Verringerung des transmembranen Fluxes oder im Anstieg der transmembranen Druckdifferenz mit der Zeit nieder. Als Folge des Foulings müssen die Membranen regelmäßig physikalisch bzw. chemisch gereinigt werden, was zu einer Verringerung ihrer Standzeit führt. Lediglich 10 % der im Klarlauf enthaltenen organischen Substanzen leisten dabei einen Beitrag zum Fouling (Laabs 2004). Diese Substanzen eluieren bei einer Größenausschlusschromatographie im sogenannten Biopolymer-Peak, der sowohl Polysaccharide als auch organische Kolloide und Proteine umfasst. In Studien zum Fouling von Niederdruckmembranen wurden Biopolymere (BP) in Form von Proteinen und Polysacchariden sowie Partikel und Kolloide in der Größenordnung von 10 bis 450 nm als Hauptverursacher des Membranfoulings ermittelt (Zheng 2009, Poele 2006). Im Rahmen des Projekts „Oxeram“ (Technische Universität Berlin, KompetenzZentrum Wasser Berlin, Berliner Wasserbetriebe) wird untersucht, ob durch eine Ozonierung vor der Flockungsstufe das Fouling der nachgeschalteten Membran reduziert und somit die Leistungsfähigkeit der Membranfiltration verbessert werden kann und ob sich aus deKombination dieser Prozesse synergetische Effekte ergeben. Eine Ozonierung kann bei einem Einsatz von geringen Ozondosen (1 - 2 mg/O3/L) in Kombination mit einer Flockung aufgrund des Mikroflockeneffekts zu größeren, stabileren und robusteren Flocken führen. Diese können sich bei einer nachgeschalteten Membranfiltration positiv auf die Filtrationsleistung auswirken. Höhere Ozondosen (10 - 12 mg O3/L) dienen der Oxidation von organischen Wasserinhaltsstoffen und Spurenstoffen. Die hier dargestellten Ergebnisse beziehen sich auf Versuche, die in AmiconTestzellen im Labormaßstab durchgeführt wurden. Ziel war es zunächst, eine optimale Kombination von Ozoneintrag und Flockungsmittelkonzentration zu ermitteln.

Low-pressure membrane filtration of secondary effluents allows disinfection and, combined with chemical coagulation, advanced phosphorus removal. However, the loss of filtration performance due to membrane fouling is still a fundamental problem and has a strong impact on the costs of the process. Biopolymers as well as colloids in the range of 50 to 350 nm were identified as main foulants during ultrafiltration (UF). In this project the impact of a pre-treatment by ozonation (2-10 mg O3/L) and subsequent coagulation (FeCl3: 2-6 mg Fe3+/L) on the performance of a polymer UF membrane was studied. No free dissolved ozone was in contact with the membrane. Lab tests were performed using Amicon test cells in dead-end mode fed with 500 mL secondary effluent of the WWTP Ruhleben (Berlin) and the flux decline during filtration was measured. The effect of the two pre-treatment steps on the character of DOC, especially the biopolymer fraction, was investigated using size exclusion chromatography. The pre-treatment enables phosphorus removal of 75 up to 95 % with permeate concentrations of 30 to 50 µg P/L. In filtration tests pre-ozonation without flocculation leads to a less distinct flux decline (1-7 %). Coagulation without pre-ozonation increases the flux by 5 to 14 % compared to filtration of effluent without pre-tretament. The combination of both pretreatment steps improves the filtration performance up to 30 % and reduces the filtration time for 500 mL by 50 %. Different mechanisms are considered as reasons for the improved performance. It is known that coagulation partially removes the fouling-active biopolymers and humic substances. The pre-treatment with ozone, even at low dosages (2 mg/L), leads to a significant decrease of UV254 absorbance, pointing on a shift to more polar molecules. Higher ozone dosages (> 6 mg/L) additionally induce disintegration of biopolymers and a shift to smaller organic compounds. The interaction between ozonation and coagulation leads to a partial complexation of iron in solution. As a consequence, less iron is provided for the coagulation process. As the percentage of complexation of iron decreases with increasing coagulant dosage, the synergetic effect of pre-ozonation and coagulation on the filtration performance increases with increasing iron dosage. These results suggest that combining pre-ozonation and coagulation can be a promising pretreatment process to reduce the fouling of organic membranes, without the necessity of applying free dissolved ozone on the membrane surface.

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.