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Danijela Milosevic and Martina Winker, ISOE - Institute for Social-Ecological Research, Germany
Why water?
The city is dependent on water, because water plays an essential role for its development and functioning. The functions of water are diverse and cover not only domestic purposes and discharge of waste but also include ecological functions. These are linked to green space management, landscape design, crop cultivation and biodiversity. But also functions such as temperature buffering are becoming more important. Water thus forms a cross-sectional topic that integrates several areas such as climate protection, quality of life, resource and energy efficiency. These connections show the importance of water for an urban development.
Because urban planning and municipal water management have significant influence on water infrastructure, it is worth taking a closer look at the potential for sustainable development in terms of water management designs that lies here. This post mainly focusses on the discourses and the developments in the German context.
Water infrastructure for a sustainable urban development – an example
One way towards sustainable development is to close water and resource circuits at the city-level. This decreases the city’s water requirement from, and its influence on, the ecosystem and makes itself more independent and resilient. Technical intelligent solutions that serve this purpose are based on the separate collection of various wastewater streams, targeted and appropriate water treatment, the recirculation of water resources, and the recovery of nutrients and organic matter contained. The New Sanitation Systems (NASS) offer solutions to these principles. Many of these technologies focus on domestic wastewater, which plays a central role in urban areas. Due to its modular design and the choice of the degree of centrality, such solutions can be combined and implemented at the level of the bathroom, the house, the block, the neighborhood or even the whole city.
An example of an innovative system solution that enables the transformation of the existing water infrastructure is shown in Figure 1. The separate collection of greywater (low contaminated wastewater produced during showering and hand washing or from the washing machine and in some cases from the kitchen sink) allows an uncomplicated treatment and heat recovery. After all, the average water temperature leaves the building at 22°C (Berliner NetzwerkE, 2011). The recovered heat is used to heat drinking water and to support heating spaces in the house. The treated greywater can then be used for toilet flushing, for the washing machine, to irrigate green spaces or to supply a nearby water body. The blackwater (wastewater from toilets) is transported with minimal water content through vacuum or excess pressure. Its organic material can generate energy by the means of a biogas plant or substrate for soil by a composting facility. As for the rainwater management, green r