ConstructioNews
Vol 34 No 1 (09-2024)
Deep Dive into Tseung Kwan O Desalination Plant - First plantation to use reverse osmosis in Hong Kong
Tseung Kwan O Desalination Plant (TKODP) aims to alleviate water supply problems caused by rising population, climate change, and competition for water resources with the Pearl Delta Area. It is the first waterworks to utilise reverse osmosis (RO) technology in Hong Kong. The project is delivered as a Design, Build and Operate (DBO) contract, with the design and build period spanning from December, 2019 to the second quarter of 2024, followed by 10 (plus an optional 5) years of operation period. The first stage of the plant started construction in December, 2019 and began operation in December, 2023.
Located in Tseung Kwan O Area 137 of about 10 hectares, the desalination plant is close to the seaside. The nearby seawater has low turbidity with relatively stable water quality, making it suitable for desalination.
The plant will produce up to 135,000 cubic metres of drinkable water per day during its first stage, amounting to about 5 percent of Hong Kong’s intake. The plant, together with the Pak Kong Water Treatment Works and the Tseung Kwan O Primary Fresh Water Service Reservoir, will supply drinking water to Sai Kung, as well as parts of East Kowloon and Hong Kong Island.
Reverse Osmosis
RO technology accounts for more than 60 percent of global desalination production. The first stage of the TKODP has 12 reverse osmosis racks with a total of 2,336 reverse osmosis pressure vessels installed in the racks. Each vessel contains seven spiral reverse osmosis membrane elements, and this is where the reverse osmosis process takes place.
Seawater entering the TKODP will undergo four main stages of treatment: screening, pre-treatment, reverse osmosis, and post-treatment. Extracted seawater will first be screened and pre-treated to prevent marine organisms from entering the facility and removing impurities and suspended solids. After that, reverse osmosis technology will be used to remove salt, impurities and micro-organisms from the pre-treated seawater.
Osmosis is a natural phenomenon where fresh water migrates from low salinity to high salinity. The principle of reverse osmosis is to apply excessive pressure on the seawater side to force water from the seawater through a semi-permeable membrane to the fresh water side so as to remove salt, impurities and micro-organisms to purify seawater.
After the reverse osmosis process, permeate will go through a post-treatment process where chemicals are added to adjust water hardness and pH levels, etc. to meet the Hong Kong Drinking Water Standards.
After all treatment processes, seawater becomes potable water, which will then be blended with treated water from the Pak Kong Water Treatment Works at the Tseung Kwan O Primary Fresh Water Service Reservoir, providing potable water for Sai Kung, East Kowloon and part of Hong Kong Island.
Design for Manufacture and Assembly (DfMA)
About 40 percent of construction work at TKODP have adopted the DfMA approach. Parts of the RO racks were assembled in Shanghai before being shipped to Hong Kong. The RO racks were delivered to TKO site for installation after the superstructure of the RO building was completed. DfMA panels were then installed.
Since civil works onsite progressed simultaneously as the required parts are manufactured, this improves time effectiveness while decreasing labour demand and ensuring safety.
Smart Safety
(i) Underwater Inspection Drones
Underwater inspection drones were utilised during the construction process of the intake and outfall shaft. The drone is controlled above ground and comes equipped with an eight vectored-thruster layout that allows omni directional movement, a 4k camera that records up to 100 metres deep, a replaceable battery lasting up to four hours, and two 2000 lumen LED lights. This ensures the shaft installations do not damage the marine ecosystem while also reducing the need of personnels physically surveying underwater.
(ii) Global Navigation Satellite System (GNSS)
GNSS is a satellite constellation that provides real time positioning and navigation on a global or regional scale. The system is able to accurately measure latitude and longitude with a margin of error 2 millimetres. The team is able to monitor a site’s live location at all times by installing a GNSS. Solar panels with an IP67 water resistance rating are also installed at the shaft to provide self-sufficient power.
During the planning stage, the team opted to use GNSS to monitor the fluctuation of the temporary shafts from sea waves or construction. The process of building the intake and outfall shafts required temporary shafts and support systems. Workers would also periodically survey the sites to ensure it is up to safety standards. GNSS decreased the need for personnels to survey the shafts directly, which increases safety while simplifying the surveying process.
(iii) AI Cameras
The AI cameras automatically detect, record, and notify other project members if a worker is not abiding to the safety standards. The cameras are installed at four strategic locations to ensure the safety of workers at all times.
The first camera is installed at the entrance of the construction site which checks if a worker is wearing a safety helmet or not. The second camera is located at the scaffolding area, checking if the workers up high are wearing a safety belt. The third camera is set for monitoring of site personnel’s entrance to dangerous /restricted zones. The last camera is installed by the dock to check if workers are wearing a life jacket.
(iv) Lifting Appliances and Lifting Gear (LA/LG) Management Systems
Due to the large amount of lifting required, an LA/LG management system is employed for the project to enhance workplace safety. The system combines QR code, mobile app and centralised platform.
Lifting appliances and gears are thoroughly examined when they arrive at the site and have their data uploaded to the system. The system will then generate a unique QR code for each appliance, where personnels can scan it with their mobile devices to check the statutory forms and other relevant information. If an error is spotted, a report can be made and automatically notify relevant contractors for follow-ups. Personnels at the central platform can also check the positions and data of the appliances. These measures lowers the chances of working with outdated or damaged appliances. Moreover, it also allows contractors to access data of the equipment, leading to more transparency and management efficiency.
(v) 360° Smart Monitoring System
A safety monitoring system is installed on heavy construction plant for obstacles detection and real-time acquisition of surrounding environment. It provides synthesised image with 360° bird’s-eye view, panoramic detection of obstacles within 1 metre, and siren and signal light when there are obstacles in the detection range, thus improving workers’ safety when plant is in operation.
Second Stage Construction
The Water Supplies Department has started the preliminary design for the second stage of the plant, and the adjacent site is also earmarked for future expansion, with a water production capacity that will meet around 10 per cent of the overall fresh water demand in Hong Kong.
Source of Information and pictures: TKO Desalination Plant Website of Water Supplies Department
Located in Tseung Kwan O Area 137 of about 10 hectares, the desalination plant is close to the seaside. The nearby seawater has low turbidity with relatively stable water quality, making it suitable for desalination.
The plant will produce up to 135,000 cubic metres of drinkable water per day during its first stage, amounting to about 5 percent of Hong Kong’s intake. The plant, together with the Pak Kong Water Treatment Works and the Tseung Kwan O Primary Fresh Water Service Reservoir, will supply drinking water to Sai Kung, as well as parts of East Kowloon and Hong Kong Island.
Reverse Osmosis
RO technology accounts for more than 60 percent of global desalination production. The first stage of the TKODP has 12 reverse osmosis racks with a total of 2,336 reverse osmosis pressure vessels installed in the racks. Each vessel contains seven spiral reverse osmosis membrane elements, and this is where the reverse osmosis process takes place.
Seawater entering the TKODP will undergo four main stages of treatment: screening, pre-treatment, reverse osmosis, and post-treatment. Extracted seawater will first be screened and pre-treated to prevent marine organisms from entering the facility and removing impurities and suspended solids. After that, reverse osmosis technology will be used to remove salt, impurities and micro-organisms from the pre-treated seawater.
Osmosis is a natural phenomenon where fresh water migrates from low salinity to high salinity. The principle of reverse osmosis is to apply excessive pressure on the seawater side to force water from the seawater through a semi-permeable membrane to the fresh water side so as to remove salt, impurities and micro-organisms to purify seawater.
After the reverse osmosis process, permeate will go through a post-treatment process where chemicals are added to adjust water hardness and pH levels, etc. to meet the Hong Kong Drinking Water Standards.
After all treatment processes, seawater becomes potable water, which will then be blended with treated water from the Pak Kong Water Treatment Works at the Tseung Kwan O Primary Fresh Water Service Reservoir, providing potable water for Sai Kung, East Kowloon and part of Hong Kong Island.
Design for Manufacture and Assembly (DfMA)
About 40 percent of construction work at TKODP have adopted the DfMA approach. Parts of the RO racks were assembled in Shanghai before being shipped to Hong Kong. The RO racks were delivered to TKO site for installation after the superstructure of the RO building was completed. DfMA panels were then installed.
Since civil works onsite progressed simultaneously as the required parts are manufactured, this improves time effectiveness while decreasing labour demand and ensuring safety.
Smart Safety
(i) Underwater Inspection Drones
Underwater inspection drones were utilised during the construction process of the intake and outfall shaft. The drone is controlled above ground and comes equipped with an eight vectored-thruster layout that allows omni directional movement, a 4k camera that records up to 100 metres deep, a replaceable battery lasting up to four hours, and two 2000 lumen LED lights. This ensures the shaft installations do not damage the marine ecosystem while also reducing the need of personnels physically surveying underwater.
(ii) Global Navigation Satellite System (GNSS)
GNSS is a satellite constellation that provides real time positioning and navigation on a global or regional scale. The system is able to accurately measure latitude and longitude with a margin of error 2 millimetres. The team is able to monitor a site’s live location at all times by installing a GNSS. Solar panels with an IP67 water resistance rating are also installed at the shaft to provide self-sufficient power.
During the planning stage, the team opted to use GNSS to monitor the fluctuation of the temporary shafts from sea waves or construction. The process of building the intake and outfall shafts required temporary shafts and support systems. Workers would also periodically survey the sites to ensure it is up to safety standards. GNSS decreased the need for personnels to survey the shafts directly, which increases safety while simplifying the surveying process.
(iii) AI Cameras
The AI cameras automatically detect, record, and notify other project members if a worker is not abiding to the safety standards. The cameras are installed at four strategic locations to ensure the safety of workers at all times.
The first camera is installed at the entrance of the construction site which checks if a worker is wearing a safety helmet or not. The second camera is located at the scaffolding area, checking if the workers up high are wearing a safety belt. The third camera is set for monitoring of site personnel’s entrance to dangerous /restricted zones. The last camera is installed by the dock to check if workers are wearing a life jacket.
(iv) Lifting Appliances and Lifting Gear (LA/LG) Management Systems
Due to the large amount of lifting required, an LA/LG management system is employed for the project to enhance workplace safety. The system combines QR code, mobile app and centralised platform.
Lifting appliances and gears are thoroughly examined when they arrive at the site and have their data uploaded to the system. The system will then generate a unique QR code for each appliance, where personnels can scan it with their mobile devices to check the statutory forms and other relevant information. If an error is spotted, a report can be made and automatically notify relevant contractors for follow-ups. Personnels at the central platform can also check the positions and data of the appliances. These measures lowers the chances of working with outdated or damaged appliances. Moreover, it also allows contractors to access data of the equipment, leading to more transparency and management efficiency.
(v) 360° Smart Monitoring System
A safety monitoring system is installed on heavy construction plant for obstacles detection and real-time acquisition of surrounding environment. It provides synthesised image with 360° bird’s-eye view, panoramic detection of obstacles within 1 metre, and siren and signal light when there are obstacles in the detection range, thus improving workers’ safety when plant is in operation.
Second Stage Construction
The Water Supplies Department has started the preliminary design for the second stage of the plant, and the adjacent site is also earmarked for future expansion, with a water production capacity that will meet around 10 per cent of the overall fresh water demand in Hong Kong.
Source of Information and pictures: TKO Desalination Plant Website of Water Supplies Department