In the coastal city of Rabigh in southwestern Saudi Arabia, a project aimed at obtaining fresh water from the sea has entered its peak construction period. This is the Rabigh IV seawater desalination project undertaken by Chinese enterprises in Saudi Arabia. After the project is put into operation, 1.5 million tons of seawater will enter the water intake pump room through the water intake pipeline every day, go through multiple "checkpoints" such as pretreatment, high-pressure pump pressurization, reverse osmosis seawater desalination, and post-treatment, and ultimately produce 600000 tons of clean domestic water, benefiting thousands of households. At the construction site, large-scale facilities have taken shape: two rows of 42 dual medium pressure filters with a capacity of 1100 cubic meters are neatly arranged; The steel structure reverse osmosis factory building, covering an area of nearly 12000 square meters, stands tall and magnificent; Eight water storage tanks with a diameter of 100 meters and a height of 19 meters stand aside... As the crawler crane with a rated lifting capacity of 750 tons slowly lowers the water intake device into the seabed, the grab ship begins the next step of construction. The core of reverse osmosis seawater desalination technology is the reverse osmosis membrane Feng Quntao, the project manager of Shandong Electric Power Construction Third Company, a subsidiary of China Electric Power Construction, introduced that seawater needs to undergo multiple filtration treatments before entering the reverse osmosis plant. Firstly, the trash rack and rotating filter screen in the water intake pump room intercept debris with a volume greater than 5 millimeters; Next, by adding coagulants and coagulants, suspended solids and colloids in seawater are condensed into flocculent substances that are easy to filter; Subsequently, seawater is sent into a dual medium pressure filter filled with materials such as pebbles, quartz sand, and pumice to further remove insoluble impurities. What if there are still impurities' leaking through the net ' Faced with the reporter's question, Feng Quntao pointed to a row of standing "cylinders" and said, "This is a security filter with a filter element with a gap of only 5 microns inside, which can effectively protect the safety of the reverse osmosis membrane." Duan Wenshuai, the chief engineer of the project, explained the reverse osmosis technology using the principle of a household water purifier: "After seawater is pressurized, it is processed by a secondary reverse osmosis system to ensure that the final water produced meets the salt content standard." The power consumption of water treatment has always been a focus of industry attention. Shandong Electric Power Construction Third Company and the owner Saudi International Power and Water Company jointly tackled the problem and adopted advanced technology to reduce the electricity consumption per ton of water production to the lowest level in the industry, only 2.773 kilowatt hours. In traditional technology, a set of reverse osmosis membrane shells is usually connected in series with 7 reverse osmosis membranes. The seawater passing through in sequence will cause a gradual loss of pressure, while the salt content of the produced water in the later stage increases. In the Rabig Phase IV project, the team innovatively installed plugs in the production water pipes of the third and fourth membranes, directly sending the low salt production water from the first three membranes into the secondary reverse osmosis system. This not only reduces the need for additional pressure, but also significantly reduces energy consumption. Feng Quntao said, "The company has rich experience in the field of seawater desalination, and has successfully constructed multiple projects such as Rabigh Phase III, Jubail Phase II, 3A, and 3B through EPC (Engineering, Procurement, and Construction) methods, which have been well received by owners and provided important guarantees for Saudi Arabia's water supply. The Rabigh Phase IV seawater desalination project demonstrates Saudi Arabia's efforts to address water scarcity issues. At present, Saudi Arabia has become the world's largest producer of seawater desalination water and one of the leaders in seawater desalination technology. As of the end of 2024, there are 43 seawater desalination plants in China, with a maximum daily output of 13.3 million tons of fresh water. At the 10th World Water Forum held in Indonesia in 2024, Saudi Deputy Minister of Environment, Water Resources and Agriculture Abdullah stated that Saudi Arabia will continuously improve seawater desalination efficiency and promote sustainable development by increasing investment and technological innovation. (New Society)