This report compiles the results of three consecutive work packages that have been worked on during the Aquisafe II project. The approach developed is based on the previous Aquisafe I project where the Soil Water Assessment Tool (SWAT) was used as an analytical instrument to develop mitigation strategies for N loads and concentrations in the Ic catchment. During Aquisage I we concluded that SWAT should include a wetland function with which the effect of artificially, constructed wetlands on solute N fluxes can be evaluated. Chapter 1 compiles results of an extensive literature review that was made to identify potential wetland routines and processes that can be included in SWAT. The SWAT add-on to be developed should allow to individually test the effect on single wetlands (e.g. in a given hydrological response unit or subcatchment) as well as the effect of multiple wetlands on the landscape scale. We therefore implemented a stand alone version of the new wetland module which is described in Chapter 2. Here we show the general functionality and individual components of the wetland module. The chapter ends with a virtual application of the modules using SWAT outputs copied from the Ic results. Additionally, a Monte Carlo based sensitivity analyses of the wetland module input parameters showed that the denitrification rate seems to be the most constrained parameter for the simulation of N turnover in the new wetland module. A full implementation of the new wetland module is described in chapter 3. Here, the structural embedment of the wetland module in the SWAT architecture is described. To proof the functionality of the SWAT wetland module model runs were compared to the stand alone version to make sure that the module was correctly implemented. We conclude that the SWAT wetland extension is ready to be tested in real world catchments. Such a full test of the SWAT wetland model was planned towards the end of Aquisafe II. However, as data from the wetlands constructed within Aquisafe II were not available in due time, this last test of the SWAT module was possible.

In Germany 35% of the total energy consumption in water utilities is due to well pumping (Plath et al., 2010). Therefore, a more efficient abstraction, besides the reduction of the carbon footprint, will lead to economic benefits for the operator. Different strategies exist for energy saving both in the operation of well fields as well as with the use of adapted, energy-efficient technical equipment (pumps, pipes, etc.) (Madsen et al., 2009). The objective of this study is the development and testing of a well field optimization tool, which is based on a hydraulic pipe network model (EPANET) but also takes steady-state well drawdown into account. The optimizer, based on coupling EPANET with the programing language R, simulates automatically the different optimization strategies (e.g. smart well field management, pump renewal) and evaluates their impact on the energy demand. The developed well field model was tested for a case study in France and predicted the measured energy demand with an error of less than 2%. The identified energy saving potential found by the optimizer reaches up to 17% in case of implementing only smart well field management and close to 50% combining the latter option with pump renewal.

Sludge treatment and disposal is one of the key positions of operating costs in large wastewater treatment plants (WWTPs). On large WWTPs, dewatering of digested sludge is mainly performed with centrifuges. The performance of the centrifuge and thus, the (cost-)efficiency of the whole sludge dewatering process, strongly depends on the operating parameters of the centrifuge and the properties/preparation and dosage of the polymer used as flocculation aid. The research project “Decamax” therefore mainly focuses on these aspects and their impact on the dewatering result, i.e. mainly the dry solid content of the sludge cake and the quality of the sludge liquor. Moreover, the impact of sludge pre-heating on sludge dewatering is assessed, because it is known that the dewatering temperature has a high influence on the process as well. Besides a technical study (Work Package 3) and full-scale trials at a WWTP in Berlin (WP 1), the project included trials with a 0.4 m³/h pilot-scale centrifugation unit in Braunschweig (Work Package 2). The results of this work package (performed by the Institute of Sanitary and Environmental Engineering, Technische Universität Braunschweig (ISWW)) are summarised in this report. Besides the ISWW, the pilot-scale trials were supported and evaluated by the Stadtentwässerung Braunschweig (SE|BS), the KompetenzZentrum Wasser Berlin (KWB) – also responsible for the overall project management and control – and Kläranlagenberatung Kopp (KBK). Moreover, the Decamax project team and technical committee include the Berliner Wasserbetriebe (BWB) and Veolia Wasser. The project is financially supported by Veolia Water and BWB.

Unbehandeltes Abwasser ist ein wertvoller Energieträger. Die hier enthaltenen organischen Stoffe haben so viel chemische Energie, dass sich damit die bisher in der Abwasserbehandlung benötigte Energiemenge komplett kompensieren und sogar noch ein Energieübersch uss erzeugen ließe. Wissenschaftler vom Kompetenzzentrum Wasser Berlin (KWB) haben einen neuen Prozess der Abwasserbehandlung entwickelt und im Pilotmaßstab getestet, um das erhebliche Energiepotenzial im Abwasser besser auszuschöpfen. Das Forschungsprojekt CARISMO ("CARbon IS MOney") hat eine Expertenjury für den Deutschen Nachhaltigkeitspreis nominiert.