Synergistic benefits between stormwater management measures and a new pricing system for stormwater in the City of Hamburg.

Hamburg is a growing metropolitan city. The increase in sealed surfaces of about 0.36% per year and the subsequent increased runoff impacts on the city's wastewater infrastructure. Further potential risks to the drainage infrastructure arise also from effects of climate change, e.g. increased intensity and frequency of heavy rainfalls. These challenges were addressed in the Rain InfraStructure Adaption (RISA) project conducted 2009-2015 by HAMBURG WASSER and the State Ministry for Environment and Energy, supported by several municipal stakeholders. RISA addressed intensifying conflicts in the context of urban development and stormwater management at that time. Major results of the project are improvements and recommendations for adequate consideration of stormwater management issues during urban planning as well as new funding mechanisms for stormwater management measures. The latter topic resulted in the introduction of a separated stormwater charge based on the amount of sealed area connected to the sewer system of each property. For both undertakings - the RISA project and the introduction of the separated stormwater charge - a novel, comprehensive, digital database was built. Today, these geographical information system (GIS)-based data offer various scale-independent analysis and information opportunities, which facilitate the day-to-day business of HAMBURG WASSER and stormwater management practice in Hamburg.

Characteristics of source-separated household wastewater flows: a statistical assessment.

Knowledge of concentrations or loads in wastewater flows is a basic prerequisite for the design of wastewater treatment units and the assessment of the environmental impacts. With respect to new sanitation concepts that are based on the source-separation of domestic wastewater flows not much general data is available yet on characteristics or design values of the different flows. A desk study of more than 130 references was carried out in order to arrive at design values for different source-separated wastewater flows including the fractions urine, faeces and greywater. The evaluation was carried out focussing on European data. The different values were analysed by the use of statistical parameters. In order to arrive at design values for different parameters, the median as well as minimum-maximum ranges of the available data were calculated. The collected data include volumes and characteristics like organic pollution (COD and BOD), nutrients (N, P, K & S) and heavy metals for the different source-separated flows. Loads and concentrations are listed respectively. A comparison is drawn between data from different regions in order to assess the impact of differences in nutrition and habits.

Material flow analysis as a tool for sustainable sanitation planning in developing countries: case study of Arba Minch, Ethiopia.

Material Flow Analysis is a method that can be used to assess sanitation systems with regard to their environmental impacts. Modelling water and nutrients flows of the urban water, wastewater and waste system can highlight risks for environmental pollution and can help evaluating the potential for linking sanitation with resource recovery and agricultural production. This study presents the results of an analysis of nitrogen and phosphorus flows of Arba Minch town in South Ethiopia. The current situation is modelled and possible scenarios for upgrading the town's sanitation system are assessed. Two different scenarios for nutrient recovery are analysed. Scenario one includes co-composting municipal organic waste with faecal sludge from pit latrines and septic tanks as well as the use of compost in agriculture. The second scenario based on urine-diversion toilets includes application of urine as fertiliser and composting of faecal matter. In order to allow for variations in the rate of adoption, the model can simulate varying degrees of technology implementation. Thus, the impact of a step-wise or successive approach can be illustrated. The results show that significant amounts of plant nutrients can be provided by both options, co-composting and urine diversion.