How a new Hong Kong desalination plant placed sustainability at the heart of its design

The Tseung Kwan O desalination plant, which is due to start operations by the end of 2023, is a crucial part of Hong Kong’s water management strategy.

It aims to build resilience and mitigate the effects of climate change.

Hong Kong’s water supply is facing challenges including increased demand, extreme weather, and competition from the Pearl Delta area.

Diversifying its water sources beyond rainwater collection and Dongjiang water import is therefore vital.

As Hong Kong is a peninsula, desalination is a promising potential new water source.

How is the Tseung Kwan O desalination plant being built?

The plant is being built on eight hectares of former landfill to eliminate the need for virgin land or reclamation.

It’s located close to Hong Kong’s population centres and pipeline network to allow for efficient water distribution.

The first phase of the development will have a water production capacity of 135 million litres per day.

This is equivalent to 5% of Hong Kong’s total daily demand and enough for more than 370,000 people.

The ultimate plan is to double capacity to 270 million litres per day.

Green credentials

The plant has been designed with sustainability in mind. Its features include:

• ActiDAFF – an integrated structure combining flotation and filtration processes that will reduce the plant’s carbon footprint. When incoming seawater has only a limited amount of impurities, air flotation will be unnecessary and switched off to save energy.
• Reverse osmosis – positive displacement energy recovery devices will recover up to 96% of the pressure energy from the brine, reducing the required pumping energy by up to 50%.
• Pressure centre configuration for high-pressure pumps – this will enable the use of large, fixed speed pumps, which increases efficiency.

Numerous other elements reflect the project team’s efforts to alleviate the effects of climate change wherever possible.

Making the plant sustainable

In addition to installing more than 1,800 roof solar panels, planning is under way for a large-scale 10MW solar panel farm that will generate electricity solely for the plant’s use.

Design for Manufacture and Assembly (DfMA) and Multi-trade integrated Mechanical, Electrical and Plumbing (MiMEP) methods are being used in the construction process.

Many elements are being fabricated offsite before being assembled onsite.

This will improve safety and quality as well as reducing waste and transportation to lower the project’s embodied carbon.

Lots of greenery will be provided to help the plant blend in with the surrounding rural environment.

Grey water re-use and rainwater harvesting will be adopted to reduce freshwater consumption by more than 50%.

Such measures have led to the project achieving a top platinum rating in its provisional assessment by BEAM Plus, a set of green building assessment tools designed to evaluate building sustainability in Hong Kong.