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Case Studies for Options of Sustainable Sewage Sludge Disposal in China - Abstract and Conclusive Information - Dr. Weimin Shen, Kocks Consult, Koblenz, Germany. Introduction of the Project “Case Studies”. Financed by KfW Conducted by a consulting consortium with following members
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Case Studies for Options of Sustainable Sewage Sludge Disposal in China - Abstract and Conclusive Information - Dr. Weimin Shen, Kocks Consult, Koblenz, Germany
Introduction of the Project “Case Studies” • Financed by KfW • Conducted by a consulting consortium with following members • Ingenieure Meschke und Schuster • Dahlem Beratende Ingenieure • Hamburger Stadtentwässerung • Kocks Consult • NCMEDRI • Supported by seven major cities in China
Present Situation of Landfills • Disposed within WWTP sites or dumped on public areas • Shortcomings of disposal of sewage sludge on sanitary landfills: • such as high water content, low shear strength and insufficient stabilization Present problems with operation and safety • Limited sanitary landfill capacity for medium or long term needs
Future Development of Landfills • Advanced preconditions for sludge characteristic for disposal on sanitary landfill • water content of sewage sludge less than 65% • shear strength of sewage sludge more than 25kN/m2 Additional costs for sludge post-treatment on WWTP • Requirements for location and operation of sanitary landfill • distance to cities with regard to the environmental protection • advanced treatment of landfill gas and seepage water Additional costs for transportation and operation
Future Development of Landfills • In general, the total costs for sludge disposal on sanitary landfill will increase significantly in the future. • In the long term, such solutions are not sustainable for major cities due to shortage of landfill capacity.
Present Situation of Agricultural Use • Reasons for the lack of positive examples • does not comply with regulations and standards, such as concentration limits for relevant pollutants in sewage sludge • no stable and sustainable market needs, such as available farmland • no sufficient control and management, such as limits for quantity, time and location • minor acceptance of public, especially against the epidemic risks such as SARS in China
Future Development of Agricultural Use • Advanced preconditions for agricultural use • limits for pollutant concentrations in sewage sludge • limits for sludge application quantities • limits for use objects and sites, such as forestry or non-food products • limits for contaminants concentrations in the soil • Agricultural use should be considered as the most economic solution if the above mentioned pre-conditions can be fulfilled. • In the future, the agricultural use will play only a minor role for major cities in China.
Present Situation of Incineration • A high potential for sludge incineration has been identified since last years. • Realized mono-incineration, for example: • Shanghai • Realized co-incineration, for example: • Changzhou in coal power plant • Suzhou in coal power plant • Nanjing in coal power plant • Beijing in cement industry
Future Development of Incineration • In the future, co-incineration will play a important role for the sludge disposal in major cities in China. • Simple pre-conditions on co-incineration in coal power plants • water content of sewage sludge less than 80% available Possibly: maybe limited capacity of one coal power plant • High acceptance of coal power plants • generation of extra income • reuse of ashes • no additional measures for waste gas cleaning But: investment for installation of a station for reception, storage and dosage
Conclusion • Agricultural use plays a minor role for major cities and will not be applicable on a large scaled. • Landfill is generally limited by scare capacities of the existing landfill sites and an intermediate solution for the following years. • Clear preference is given to the sludge incineration in coal power plants if available.
Outlook • Small Cities Landfills are present and pragmatic solutions for most small cities. If possible, it should be tried to realize agricultural use as the most economic option. • Major Cities Landfills are only intermediate solutions before other options will be realised. Co-incineration will be the preferred option for major cities in the future, if facilities are available.
Thank you for your Attention ! Address: Dr.-Ing. Weimin Shen Kocks Consult GmbH Stegemannstr. 32-38, D-56068 Koblenz, Germany Tel.: +49 (0)261 / 1302-162 Fax. : +49 (0)261 / 1302-152 E-Mail: shen@kocks-ing.de