Facility Doubles Output While Setting New Standards for Sustainability
The same thing that helps make water safe to drink also can cause serious illness, even death.
With that kind of responsibility, the Hong Kong Water Supplies Department is bringing more clean drinking water to its citizens in much safer ways.
Ultimately, the department set out to double the Tai Po Water Treatment Works’ production to 800 million liters per day (211 million gallons per day). Achieving that goal was an amazing feat in itself, but the department saw beyond the infrastructure to boldly address the equally complex challenge of safe and sustainable treatment.
Meeting that objective required a commitment to innovative technology. The department’s Tai Po Water Treatment Works led the way in making life’s critical resource even more accessible to one-third of Hong Kong’s people.
That achievement started with a challenge the supplies department was determined to overcome. One of the most crucial elements necessary for water treatment - chlorine - was not available in Hong Kong and was imported from China in its liquid form.
Transportation and storage of chlorine could be dangerous. Past spills on roadways, railways and at industrial facilities have caused death and serious injuries around the world, including long-term respiratory and stomach disorders.
Producing Chemicals Onsite and On Demand
In response, the Water Supplies Department focused not only on expansion and water supply resilience, but on sustainably generating ozone and chlorine gas on site at the Tai Po facility. Both elements efficiently remove pathogens to make water safe for humans. On-site creation eliminates the need to transport chlorine, thus protecting public safety.
The department generates ozone gas using vacuum pressure swing adsorption, and chlorine gas is created by electrolyzing brine from food-grade salt. The use of ozone, in addition to chlorine, allows the Tai Po facility to decrease chlorine requirements by about 30 percent. Plus, the chlorine is produced as it’s needed, which eliminates the need for potentially hazardous on-site storage.
The expansion of the treatment works and integration of on-site disinfectants is a pioneering effort that sets an example of environmental sustainability and resilience for 11 other major water treatment facilities in Hong Kong. In addition, the plant’s increased production supplies more fresh water to residents of Tai Po, Kowloon and the Central and Western districts of Hong Kong.
The Tai Po WTW is also now one of the largest municipal water treatment installations in the world with on-site generation of both ozone and chlorine gas.
Saving Water and the Environment, Safely
“The project represents the Hong Kong Water Supplies Department’s vision to improve the reliability and flexibility of water supply and distribution networks,” said Luk Wai-Hung, Assistant Director of New Works for the department. “Tai Po Water Treatment Works is at the forefront of environmental innovation and stewardship.”
Black & Veatch*, which has worked in Hong Kong since the 1930s, designed the facility and provided construction management supervision for the project. To maintain future safe operation of four on-site chlorine generation units, the company also helped create a Building Information Modelling (BIM), augmented-reality mobile application that trains operators in safety procedures. Black & Veatch also designed Stage 1 of the award-winning plant that came online in early 2005.
The plant also features a zero-water discharge design, which means nearly every drop of water, including what’s used for operations, is treated for reuse.
“We cherish our water resources and have achieved a water-conversion efficiency of 99.7 percent,” said Thomas Chan, Chief Engineer for the department. “We’re also using gravity discharge and on-site solar panels to decrease our demand for electricity from the grid.”
*A project undertaken in Hong Kong SAR when Black & Veatch owned that business.