HONG KONG, January 30, 2026 /PRNewswire/ — SUEZ was rewarded the contract for the supply of sludge dewatering solution for the relocation of Sha Tin wastewater treatment plants to caverns by the Drainage Services Department (DSD) of the Hong Kong SAR Government. The project will be carried out by SUEZ, relying on sludge dewatering technology developed and continuously improved for more than 15 years thanks to SUEZ’s collaboration with Bucher Unipektin AG.[1]. This sludge dewatering contract covers the design, equipment supply and delivery of the new Sha Tin Cavern Wastewater Treatment Plant (STCSTW).
Scheduled to be completed in 2030, the new facility is expected to become one of Asia’s largest wastewater treatment plants, built in an artificial cave. With its compact design and advanced process standards, the STCSTW will optimize land use and set a new benchmark for green and sustainable infrastructure in Hong Kong.
New cavern wastewater treatment facility to meet sanitation needs and relieve land pressure
Sha Tin’s existing wastewater treatment plants have served approximately 700,000 residents for more than 40 years. As the facility was in need of modernization, the DSD decided to not only address the challenge of aging facilities, but also address the acute problem of land shortage and improve the surrounding community environment.
The DSD initiated the relocation of the Sha Tin wastewater treatment plants to a purpose-built cavern, comprising a 14-hectare site and an upstream wastewater collection system. This strategic approach brings major benefits to the population of Hong Kong: it will limit olfactory nuisances since the caves act as natural barriers which contain and attenuate odors. Additionally, inside the cavern, odor sources will be enclosed and dedicated deodorization facilities will be installed. It will free up 28 hectares of land for other beneficial uses.
Long-term technology collaboration between SUEZ and Bucher Unipektin AG to support cavern operations in Hong Kong
Recognizing the constraints of cavern installations, including limited space, controlled access and strict safety requirements, SUEZ will equip the 16-unit project with its proven Dehydris™ Twist sludge dewatering system. Fully enclosed and highly automated, this system allows for safer operations in confined areas and helps reduce operator exposure. Its compact design reduces footprint by 25% and provides greater flexibility for allocating other essential cavern equipment.
The Dehydris™ Twist sludge dewatering solution has proven stable and reliable in SUEZ projects in France, Italy, Australia and mainland China. In Hong Kong, seawater flushing for approximately 85% of the population increases the salinity of wastewater, typically between 5000 and 6000 mg/L, which can influence dewatering performance.
To confirm the results under local conditions, Dehydris™ Twist was tested in Hong Kong for several years. Trials have shown consistent performance, increasing solid sludge content from approximately 3% to as much as 30%, thereby reducing sludge volume and associated transportation and disposal costs. The system is expected to produce approximately 120,000 tonnes of dewatered sludge per year, supporting energy recovery and Hong Kong’s circularity and carbon emissions reduction targets.
Commenting on the long-term technological collaboration supporting this project, Daniel Schneider, CEO of Bucher Unipektin AG, said: “The implementation of Bucher HPS technology at the new STCSTW as part of the SUEZ Dehydris™ Twist workshop marks an important step in recognizing the growing need for advanced biosolids dehydration solutions. Our technology sets new standards in efficiency and sustainability, demonstrating what is now achievable in modern wastewater treatment.
Pierre Pauliac, Deputy General Manager of SUEZ, in charge of international activitiessaid: “This project represents an important opportunity for SUEZ to deliver its core business sludge dewatering solution for the new cavern wastewater treatment plant, integrate our global expertise to create local value for Hong Kong. In the Greater Bay Area, we have been committed to providing sustainable environmental solutions for decades.: exploitation of two waste water processing plants in Hong Kong for improve the aquatic environment; provide quality drinking water services to the entire city of Macau; and support Guangdong industries with advanced wastewater treatment solutions for It is green transition. In the future, wWe will continue to leverage our water and waste expertise, working closely with all stakeholders to lead the Greater Bay Area toward a greener, more resilient and sustainable future.“
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[1] Bucher Unipektin AG, a subsidiary of Bucher Industries |
About SUEZ:
Faced with growing environmental challenges, SUEZ has been providing essential services that protect and improve our quality of life for more than 160 years. SUEZ offers its customers innovative and resilient solutions for water and waste services. With 40,000 employees spread across 40 countries, the Group supports its clients to create value throughout the life cycle of their assets and services, and manage their low-carbon transition. In 2024, SUEZ provided drinking water to 68 million people around the world and sanitation services to 44 million people. The Group generated 8 TWh of energy from waste and wastewater. In 2024, SUEZ generated a turnover of 9.2 billion euros. For more information: www.SUEZ.com.
In Asia, SUEZ’s adventure began around 70 years ago, first in South-East Asia before expanding to China 50 years ago. With more than 6,500 employees in Asia, SUEZ has built more than 600 water and wastewater treatment plants. Today, SUEZ works with municipal and industrial customers in more than 30 major cities and regions, providing water and waste recycling and recovery services to more than 25 million people and 23 industrial parks.
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