An integrated wastewater treatment and reuse concept for the Olympic Park 2008, Beijing

In a Sino-German research project, a joined developed sustainable water reclamation concept was developed for different applications of municipal water reuse at the Olympic Green 2008. The concept combines advanced technological processes like membrane bioreactors, specific phosphorus (P) adsorption columns and ultrafiltration (UF) with nature-based treatment processes like wetland and bank filtration mechanisms. The project’s approach is not only to comply with the reclamation requests of the Olympic Green 2008, but also to give an example for better, adapted and energy efficient reuse applications throughout China. The study shows that fixed-bed granular ferric hydroxide (GFH) adsorbers after a membrane bioreactor (MBR) can maintain a total phosphorus (TP) concentration of <0.03 mg L–1. A low P concentration will be necessary to control eutrophication in the artificial Olympic Lake filled with treated wastewater. With an adsorption capacity of approx. 20 mg g–1 d.m. at a corresponding equilibrium concentration of 1 mg L–1 P, GFH reaches long operation times and can be repeatedly regenerated by caustic solutions with an efficiency of 50%. Apart from scenic impoundments, treated wastewater will be used for irrigation and toilet flushing. The latter requires a superior quality that will be delivered by low pressure UF treatment after lake (bank) filtration. A crucial reduction of fouling potential for dead-end UF is expected.

The present paper summarizes the concept and preliminary results of the Sino-German project “Wastewater Treatment and Reuse for the Olympic Park 2008”. A combination of advanced technological approaches and natural treatment processes was developed jointly to account for the necessities of water quality requirements for different water reclamation uses. Irrigation of lawn and crops, urban reuse like toilet flushing and car washing and last but not least scenic impoundment reuse for the Olympic Lake require adapted treatment processes to cover not only the needs for the Olympics, but give examples for sustainable reuse technology throughout China. For shallow artificial lakes filled with treated municipal wastewater, pathogen indicators and TP are critical parameters. TP can be reduced to values <0.03 mg L–1 by bio-P MBR systems and subsequent orthophosphate adsorption onto GFH material. The granular media shows high loading rates for phosphorus (>20 mg P g–1 d.m. at initial P concentration >1 mg L–1 and pH »7) relatively independent on the water matrix and competing ion concentrations. In laboratoryscale column tests with real MBR effluents, GFH could be repeatedly regenerated by caustic solutions with an efficiency of 50%. According to the consortiums preliminary results, the existing water reuse regulation for nutrients (TP and TN) does not seem to be sufficient if treated municipal effluents are to be used as the only source for an artificial lake in the Olympic Green. Further pilot-scale tests are in progress.