Biological Nutrient Removal System for Improving Effluent Quality at One of the Largest Municipal Wastewater Treatment Plants in China  

Siemens Water Technologies & Engineering (Tianjin) Co., Ltd. (SWTE) signed a 42 million Renminbi (approx. 4.2 million Euro) contract with Tianjin Capital Environmental Protection Group Co., Ltd. in China (TCEPC) to provide a Biological Nutrient Removal (BNR) system for upgrading and retrofitting the facilities of Tianjin Xianyang Road Wastewater Treatment Plant (Xianyang Road WWTP) in Tianjin, China. The BNR system will be designed to treat 450,000 m3 per day and to significantly improve the effluent discharge standard of Xianyang Road WWTP from the national standard of Class II to Class I. The project is scheduled for start up in April 2010.

As one of six main drainage systems in Tianjin, the Xianyang Road WWTP serves an area of 6806 hectares. The WWTP upgrade is one of the key sewage treatment projects for pollution control of the Hai River. The project was awarded to Siemens following a successful BNR pilot study conducted for TCEPC in June 2009.

The BNR system uses an aerated anoxic reactor, where simultaneous nitrification and de-nitrification occurs, followed by two aerobic reactors to increase the efficiency of total nitrogen removal when compared to conventional processes. With the BNR process, the biological reaction tank footprint is minimized, and therefore the capital cost is significantly reduced. TCEPC will not need to construct additional basins that otherwise would be required for conventional activated processes. In addition, the dissolved oxygen profile of 0/1/2 mg/l maintained in the three respective reactors greatly reduces oxygen demand, thereby reducing energy usage. The unique “Smart BNR” automation system allows optimal operation of the whole system. Not only can the BNR be easily retrofitted into existing plants, but is also ideal for new plants.