Sponge city elements impress with simplicity and efficiency. At the same time, they must fit to the specific local situation. Hence, a general design catalog helps planners to develop a suitable stormwater concept and particular sponge city elements. Several typical Sponge City elements are applied in Germany since the 1990s. In China, starting with 16 pilot cities in 2015, and 14 more in 2016, Sponge City Implementation has become one main method to deal with the urban water management issues. In Tongzhou District, Beijing, the implementation of Sponge City facilities is planned on 16 sub-catchments. Some of the already planned or realized Sponge City concepts will be reviewed and the the German partners will provide suggestions for optimization or upon special issues. For the newly started or not started catchments in Tongzhou, the German partners will support the Chinese planners with ideas and recommendations regarding concept and design. Overall, based on the specific conditions in China, a comprehensive catalogue of sponge city elements is to be developed by the German side. Alongside, the feasibility of transferring German sponge city design experience into Chinese conceptions will be evaluated.
For a better operational strategy for the Sponge City Elements, e.g. rain garden, pervious pavements, stormwater retention tank etc., information about rainfall, volume flows, hydraulic loading and water quality parameters should be collected. Accordingly, German partner NIVUS will provide the online monitoring equipment. Besides, technical training upon how to use this equipment will also be carried out on site for the Chinese partners. In addition, from the Chinese side, there is interest in monitoring and evaluating flow fractions caused by infiltration inflow into sewers and for leakage from the sewer system. In order to evaluate the already implemented Sponge city concepts, German partners will also provide an evaluation and monitoring concept. In this context NIVUS monitoring equipment for online observation of rain fall and volume flows in water systems will be available for the Chinese partners for monitoring campaigns in the Tongzhou catchment close to Beijing. The equipment will be handed out to the School of Environment of the Tsinghua University in the framework of a workshop on rainfall and flow monitoring in July 2019. The objective of the workshop is a scientific exchange about planning, implementing and evaluating results of monitoring campaigns. Further, the handling of the equipment will be introduced to the Chinese Partners. The picture shows a selection of monitoring equipment to be used in the project.
Picture shows a selection of NIVUS monitoring equipment for the application in monitoring campaigns in the Tongzhou catchment.
The Luofang WWTP is located in the Luohu District of Shenzhen City, China. Shenzhen Water Group treatment facility is being faced with the need to treat an increased hydraulic and biological load and meet more stringent regional discharge limits. In cooperation with Chinese partners, Harbin Institute of Technology (HIT) and HIT Shenzhen, the MBR-Demonstration in Project KEYS aims to promote the demand-based implementation of eco-sensitive and particularly energy-efficient wastewater treatment methods featuring new approaches like membrane processes and worm reactor (based on nematodes) in China.
The German partner Martin Systems (MS) provides two pilot MBR plants (each 14 m³/d) for the demonstration at Luofang WWTP. Chinese Partner HIT will provide a pilot scale worm reactor in combination of German MBR-technology. The pilot-scale system will be tested and validated at WWTP Luofang for at least six months. From a scientific point of view, Kompetenzzentrum Wasser Berlin (KWB) and HIT’s activities comprise the efficiency analysis of MBR and the combination effect of MRB and worm reactor.
The close cooperation with the Chinese research partners in this particular field is expected to yield a considerable knowledge growth for all parties involved.
MBR Pilot Plant on wwtp Luofang, Shenzhen (photo credit: Kuangxin Zhou)
In the Tongzhou District, the focus is on sponge city elements, which also aim at treating pollution through runoff reduction (objective: > 60% runoff reduction). Besides, there has to be an integrated approach of sewer system and WWTP (both research topics of Chinese partners). Thus, in order to simulate pollution pathways, flooding and river management covering the catchment, models were developed at larges scales.
Focusing on small scales and data offered by the Chinese partners, German partners would build up models for stormwater runoff focusing on a small sub-catchment of i.e. 1 km² in Tongzhou urban area in order to integrate the surface and thus sponge city elements in the modeling task of evaluation. Then the model should be tested, so that the sponge city strategies and scenarios can also be checked. Furthermore, based on the Chinese Sponge City evaluation criteria, a long-term strategy will also be identified and visualized.
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In WWTP, one goal in the Chinese project is to achieve a stable nitrogen removal performance and to reduce the plant footprint of biological treatment by 30 %. Another is to do an ecological assessment of the eco-complex (WWTP + Public Park) in order to characterize the ecological benefits of underground WWTPs until the end of June 2020. At last, is to achieve a stable operation, and the effluent can reach the discharge standard, even when one of the four biological treatment lines stops running because of upgrading. In the WWTP Bishui, Tongzhou District, what needs to be done are: maximizing treatable stormwater inflow; reducing energy consumption by aeration control strategies and new treatment concepts (deammonification); energy balance of WWTP Bishui + plant design to increase energy efficiency vs. CO2-Footprint; recovery of phosphorous and nitrogen. Therefore, based on the data given by Chinese partners, German partners will develop different operational strategies and plant designs, and investigate them with model-based approach using different inflow scenarios. For different applications (operational, strategic, evaluation), the model concepts and data management will also be provided. And thus, the potential ecological evaluation criteria will be identified and an evaluation method in order to evaluate the eco-complex (WWTP + public park) will be developed.
The Bishui WWTP is located in the Tongzhou District of Beijing, China. It was built into the underground and has innovative technologies implemented such as step-feed process, membrane filtration and UV-disinfection. Together with the Chinese partner “China Water Environment Group Limited” the overall objective of this demonstration is to find opportunities to further improve the design and operation of Bishui WWTP by a modelling approach.Modelling studies are carried out in order to identify possible future plant designs with the objective to achieve a reduction of the overall specific footprint of the plant, a reduction of the CO2-footprint as well as an enhancement of the energy and cost efficiency. Within the context of sponge city another important objective is to find possible ways to integrate the municipal wastewater treatment plant into the sponge city concept. Therefore it is investigated how the treatment capacity of the wastewater treatment plant could be increased with regard to combined water by application of specific operational strategies.
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