SEMIZENTRAL is an integrated, district-related infrastructure approach that has been developed for fast-growing cities, in order to meet their challenges in regard to the supply of water and the treatment of biowaste and wastewater.SEMIZENTRAL is characterised by high resource efficiency.In Qingdao (People's Republic of China), the SEMIZENTRAL Resource Recovery Centre (RRC) has been implemented for the first time worldwide, in full-scale.Water being reused for toilet flushing and irrigation is derived from greywater and blackwater from the catchment area of the RRC.Due to the integration of food waste into the anaerobic sludge treatment, the production of biogas and electricity within the RRC is increased, thus enabling an energy self-sufficient operation.The effects of source separation of wastewater and the integration of food waste on process design, energy balance, and discharged nutrient loads are evaluated.Water reuse can save energy, compared to alternative water resources.The discharged nutrient load from the wastewater treatment to the receiving water bodies decreases considerably.Nevertheless, the effort required for wastewater treatment increases.

Der Ansatz SEMIZENTRAL wurde als mögliche Lösung für Herausforderungen im Bereich der Wasserver- und Entsorgung schnell wachsender Städte entwickelt und im chinesischen Qingdao erstmalig realisiert. Für 12000 Einwohnerwerte wurde ein semizentrales Resource Recovery Center (RRC) errichtet. Ausgehend von einem Referenzentwurf erfolgte eine Anpassung an den realen Standort. Hierbei mussten insbesondere Stoffströme den lokalen Randbedingungen und die Verfahrenstechnik des Resource Recovery Centers Qingdao ShiYuan angepasst werden. Der Beitrag evaluiert den Einfluss der veränderten Stoffströme auf Verfahrenstechnik und Energiebilanz.

The development of the world population is characterized by an absolute population growth and a rapid urbanization. This process, taking place in Asia, Latin America, and Africa, poses major pressure on the affected urban regions. In Asian countries, this development is combined with high economic growth rates. At the same time, the climate change is proceeding, and the energy supply is going to become an existential problem. The rapidly growing cities therefore face the issue that the supply of infrastructures and public services lag behind the rapid urbanization. The increasing energy costs and the imperative to reduce the CO2 emissions aggravate the situation. The centralized systems which started to be implemented in the industrialized countries more than 100 years ago are no longer the appropriate way to solve these problems. The semicentralized integrated approach, recently developed for rapidly growing urban regions in China, in contrast, offers with its flexibility a sustainable solution to cope with these developments. This article presents objectives and first results of an interdisciplinary R&D project aiming at the adaptation of the semicentralized integrated approach to the case of Hanoi, the rapidly growing capital of Vietnam, to contribute to the solution of the sanitation problems of both the old City Center and the urban expansions in conjunction. This article focuses on the planning and institutional aspects. The technical questions will be presented later in separate articles. The ongoing project is conducted by the Technische Universität Darmstadt in cooperation with the National University of Civil Engineering Hanoi and an industrial partner.

The development of the world population is characterised by two trends: absolute population growth and rapid urbanisation. In the urban region of Hanoi, the capital of the Socialist Republic of Vietnam, extensive urbanisation contributes to a deficient provision of infrastructure causing environmental degradation and health problems for large parts of the population. The protection of the environment, as well as the preservation of historic urban fabric, requires new approaches to infrastructure supply. The semicentralised approach, focusing on supply and treatment structures on the neighbourhood level, offers a solution to the challenges imposed by urbanisation. Contrasting existing plans for conventional centralised sewerage systems in Hanoi, it allows the closing of certain cycles on a local level. Within an integrated approach local technologies, such as septic tanks, can be used further on. As it is process oriented, existing management structures of waste and wastewater treatment are to be considered and incorporated.

Dynamics like climate or demographic changes require a new flexibility, which existing infrastructure systems in Germany cannot perform. The general assumption centralized systems within urban areas of middle or high density offer advantages compared to decentralized structures has to be scrutinized under changing conditions. The following paper introduces an innovative approach of integrated, sector crossing infrastructure systems developed for fast growing urban areas in Asia and screens for transfer potentials of this approach, in order to develop strategies to cope with arising problems in infrastructure matters in Germany. The paper closes with strategic recommendations for changing infrastructure development and offers strategies for adapting current infrastructure elements in order to perform better under changing conditions.

Currently, the development of the world population is characterised by two trends: absolute population growth and rapid urbanisation. Especially rapid urbanisation, taking place in Asia, Latin America and Africa, poses major pressure on the affected regions. The development of e.g. Asian countries today is stamped by a combination of urbanisation with high economic growth rates. Conventional centralised infrastructure of supply, treatment and disposal of water is not able to cope with the new challenges arising from these, in history incomparable, high growth rates. Therefore new approaches to infrastructure supply and treatment systems are required - for ecological, sociocultural and economic reasons. The semicentralised approach, focusing on integrated water supply and treatment structures for wastewater and waste on the neighbourhood level, offers one possible solution to the challenges imposed by rapid urbanisation and growing resource needs. The change from centralised to semicentralised supply and treatment systems will minimise the grave discrepancy between the rapid urban growth and the provision of supply and treatment infrastructure. Integrated semicentralised supply and treatment systems face the challenge of growing amounts of wastewater and solid waste combined with rising needs of water for private households and industrial use. The semicentralised approach offers a wide range of flexibility in implementation, energy self-sufficient operation, enormous saving potentials in water demands through intra-urban water reuse and further more advantages in comparison to centralised sectored solutions as practised today.