Nexus – Water, energy and food in Asian cities

Initial situation

Cities in Asia are undergoing extremely dynamic development – the economy is growing and many people are being drawn from the countryside into towns. But with this huge growth come several challenges: supplying the population with water, food and energy, disposing of wastewater and garbage, and protecting the populace from disasters are all things which need to be safeguarded. At the same time, the people in cities responsible for these matters ought to ensure that natural resources are protected and that the city is offering its citizens a high quality of life. Only in this way can sustainable development be guaranteed long term. Because of the very dynamic situation, this can only succeed if the thinking is broken down into sectors and innovative solutions are found through synergy (Nexus) between the areas of water, energy and food security.

Concept development for eight cities in six countries

In this context, the Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ) [German Federal Enterprise for International Cooperation] is advising different key players in selected cities as part of the project: “Integriertes Ressourcenmanagement in asiatischen Städten: der urbane Nexus [Integrated resource management in Asian cities: the urban nexus]” funded by the Bundesministerium für wirtschaftliche Zusammenarbeit und Entwicklung (BMZ) [Federal Ministry for Economic Cooperation and Development] . Last year, the Fraunhofer IGB contributed to this project in the area of water and wastewater management and developed customized, innovative concepts for some of the cities. To this end, the following cities were visited, discussions held with those responsible and the initial situation analyzed in each case: Yogyakarta (Indonesia), Santa Rosa, Naga City (both in the Philippines), Ulaanbaatar (Mongolia), Rizhao, Weifang (both in the PR China), Da Nang (Vietnam) and Korat (Thailand).

The result – tailored and sustainable approaches

For each of the cities, the experts from the Fraunhofer IGB identified approaches for sustainable development in the areas investigated. For example, for a development area outside Weifang they drew up a semi-decentralized, modular water management concept using graywater for the flushing of toilets, and for Naga City a concept for the joint treatment of wastewater from a newly built housing complex, a slaughterhouse, a prison and a school. In Korat, they analyzed an existing but not satisfactorily functioning biogas plant for the treatment of organic household waste and made suggestions for improvement measures.

For a stretch of coastline in Da Nang, currently inhabited by approximately 200 000 people, the Fraunhofer IGB together with the experts from the GIZ developed a concept whose starting point is the collection of wastewater – which previously seeped into pits – through a vacuum system. The wastewater is then treated together with kitchen waste from nearby hotels; the biogas generated can in turn be used for cooking in the kitchens of the hotels. With 45 liters per inhabitant per day, this concept enables twice as much biogas to be produced as in conventional sewage treatment plants in Germany. The plan is for the purified water to be used outside of the rainy season for irrigation purposes for the intensive agricultural activity within the city; this will contribute towards less groundwater being extracted and hence the threat of salinization of the groundwater through subsequent influx of seawater being reduced. Here the nutrients can be left in the wastewater, so that a fertilizing effect is achieved at the same time.

Outlook

Because no investment resources are being made available within the context of the BMZ-financed Nexus project, the towns involved have to either finance the implementation of the proposed solutions from their own resources or apply for grants from donor organizations. In Da Nang, a decision has already been made to put into practice the vacuum system – for testing – for 110 sites. Once satisfactory testing of the vacuum system has been completed, the plan is to implement the overall concept from the end of 2015 onwards including use of the energy present in the wastewater and use of the wastewater for irrigation and fertilization.

In September 2014, the mayor of the Georgian capital Tiflis, Davit Narmania, visited the Institutszentrum Stuttgart. He showed great interest in carrying out an analysis of his town as part of the Fraunhofer Initiative ‘Morgenstadt’. The plan is to begin this together with the Fraunhofer IAO in 2015. The experience from the Nexus project will be used in the work.