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HKUST Invents a Novel Sewage Treatment Technology
HKUST Invents
a Novel Sewage Treatment Technology

"Throughout my life, I have close connections with water," said Prof Guanghao Chen of the Department of Civil and Environmental Engineering. The professor leads a research team which has invented an environmentally- friendly sewage treatment technology SANI® which had been recognized by the International Water Association (IWA) as one of the world's most successful water management systems. It may provide solutions to water-scarce coastal cities on Mainland China.

In 1978, Prof Chen went to a university in Zhejiang which had one of China's first discipline in environmental science and engineering. In 1982, he was among the top scorers in the province of Zhejiang when he took a public examination for graduates pursuing studies abroad. This eventually brought him to Kyoto University where he did his Master's and PhD in Environmental Engineering. He worked in Japan for three years as an environmental engineering consultant, after which he went to Singapore to become an environmental research scientist in the National University of Singapore. With this portfolio, it is not surprising that he was among the first generation of environmental engineers in China.

"I like water, especially wastewater," said Prof Chen half-jokingly. "Sewage is the main hazard to the environment, and proper treatment is important. Contaminated water can cause deaths."

As a civil engineer, Prof Chen could have built bridges or dams, or built his career in clean water resources or hydroelectric power. But he chose sewage. He and his research team members have been working day and night in a laboratory where there is large amount of sewage water. "I don't mind the dirt or the odour at all," he said.

Known as the 'Sulphate Reduction, Autotrophic Denitrification and Nitrification Integrated Process', SANI uses sulphate reduction bacteria, integrated with seawater toilet flushing system of Hong Kong. The novel technology boasts the following advantages:

  • Minimizes the adverse environmental impact of sewage treatment plants
  • Eliminates 90% of sewage sludge production
  • Minimizes energy consumption, odour and greenhouse-gas emission
  • Largely reduces the sewage treatment cost and space requirement by 50%

"Conventional biological wastewater treatment technology makes use of heterotrophic microbes to clean up sewage by converting organic pollutants into carbon dioxide. These microbes grow rapidly, resulting in the daily production of 2,000 tonnes of sludge in Hong Kong. Handling of sludge means high costs and the use of incinerators," Prof Chen said. "The SANI Process on the other hand, can reduce daily sludge production to 200 tonnes or below, hence reducing treatment costs and space requirement."
In recognition of his contributions, the IWA elected Prof Chen as a Fellow of the IWA and its first Fellow in Hong Kong.

Prof Chen's research team and partners include international participants from the Delft University of Technology in the Netherlands and the University of Cape Town in South Africa. In Hong Kong, he has been working with the Drainage Services Department, the Water Supplies Department and the Airport Authority for technology application. But his vision goes beyond Hong Kong. "SANI means good news to water-scarce coastal cities on the Mainland. We will be establishing a wastewater treatment laboratory at the HKUST Fok Ying Tung Graduate School for technology application. Agreements have been made with the Sun Yat-sen University to establish an innovative water treatment center, where we will jointly nurture talents in water treatment."

Prof Chen's relationship with water is definitely more than intricate.

"The SANI Process, when integrated with seawater toilet flushing and grey water reuse, gives the best results. Its strength lies in reducing freshwater demand and minimizing sludge production. It provides an economic and sustainable solution for water-scarce coastal cities in Mainland China."

— Prof Mogens Henze,
 Technical University of Denmark