HONG KONG, July 2, 2001— The recently commissioned Ngau Tam Mei Water Treatment Works is the first water treatment plant in the world to use dual-stage biological filtration with granular activated carbon (GAC) to remove ammonia, replacing break-point chlorination.
The Hong Kong $1.8 billion (U.S. $227 million) facility treats raw water from the Dongjiang, a river that is being polluted by rapid development. Water drawn from the Dongjiang in Guangdong, a province in southern China, is the primary source of drinking water for Hong Kong.
A long-term record of poor water quality guided selection of the process train at Ngau Tam Mei.
CDM, the global consulting, engineering, construction, and operations firm, designed the plant with an initial capacity of 230 million liters/day (MLD) expandable to 450 MLD. Speaking at the opening ceremony for the Ngau Tam Mei facility, Financial Secretary Donald Tsang Yam-kuen noted that the plant will provide much needed potable drinking water to the North West New Territories, where the population is projected to increase by 18 percent to more than 8 million residents within the next 15 years.
Comprehensive Pilot Program
Since many of the recommended treatment processes including ozonation had never been used in Hong Kong, CDM conducted a 14-month pilot study to confirm design criteria and optimize overall processes for the new waterworks, focusing on pre- and intermediate ozonation and biological filtration for ammonia removal.
The study accounted for seasonal variations in raw water quality and for the transition of the raw water source from river water to reservoir water each December. The pilot study clearly demonstrated that the selected treatment process could be operated safely and effectively to produce high-quality potable water under all seasonal variations in raw quality.
Efficient operations minimize cost
The on-site production of high-quality oxygen and reduced use of chemicals for treatment, such as chlorine, are environmentally friendly advancements and cost-effective operations. Automation of plant operations using a state-of-the-art supervisory control and data acquisition (SCADA) system further reduce costs by reduce the number of necessary staff. Currently a CDM Plant manager is supervising the initial operation and maintenance of the new plant in Hong Kong.
CDM is a global, full-service consulting, engineering, construction, and operations firm helping public and private clients improve the environment and infrastructure.
