Ultrasonic sand desalination device operating beside a seawater desalination plant and DAC pilot on a coastal site.
Muscat, Oman, August 20, 2025
Researchers and companies are advancing ultrasonic sea-sand desalination, a DAC-plus-desalination pilot, and a major financed desalination plant in Oman to secure materials and water for construction and industry. The ultrasonic device uses cavitation to reduce sand salt to 0.04% or lower while cutting water use compared with traditional washing. A pilot linking direct air capture with seawater desalination aims to remove about 1,000 metric tons of CO2 per year and produce fresh water. Separately, $130 million in financing was arranged for a 100,000 m³/day desalination plant west of Muscat to supply utilities and industry.
Three developments this week could affect construction, heavy industry water supply, and carbon removal. First, a new ultrasonic device has been reported to remove salt from sea sand while using less water than traditional washing. Second, a memorandum of understanding was signed to build a pilot that pairs direct air capture with seawater desalination and uses desalination brine in the carbon-removal process. Third, finance was arranged for a large desalination plant in the Middle East that will supply industrial water and be operated under a long-term contract.
As river sand becomes harder to get because of environmental rules and overuse, builders are looking to sea sand as an alternative. But sea sand carries a lot of salt, and salt left inside concrete aggregate speeds up corrosion of steel reinforcement. Corroded steel weakens structures and can lead to early failure, increasing repair costs and safety risks. For construction, regulators recommend keeping salt content very low; one government guideline sets a maximum salt level of 0.04 percent for sand used as aggregate.
A research team developed an ultrasonic washing device aimed at removing salt from sea sand faster and with less water than conventional washing. Traditional washing methods typically use about four tons of water to clean one ton of sand. The ultrasonic method mixes sea sand with water at a ratio of one part sand to two parts water and applies ultrasonic energy of 300 watts or higher for about three minutes. The process relies on cavitation, where tiny bubbles form and collapse to clear particles and boost penetration into sand grains. Tests published in a peer-reviewed journal show the method can reduce salt in sand to the 0.04 percent target or below.
The device is reported to work in confined spaces, provide non-contact cleansing, and reduce overall water use compared with standard sand washing. Researchers describe it as a way to make sea sand safer for reinforced concrete and say it could help ease pressure on river sand supplies if scaled up.
A startup signed an agreement with a state-owned water utility and a wastewater company to develop a pilot that combines seawater desalination with direct air capture (DAC). The pilot, named Project Octopus, plans to use desalination brine as a feedstock to produce a liquid sorbent that removes CO2 from the air. That CO2 can then be converted into a mineral form similar to chalk or limestone, locking it away. Fresh water is a byproduct of the combined process, meant to serve nearby heavy industry.
The pilot aims to capture roughly 500 metric tons of atmospheric CO2 per year and also filter about 500 tons of smokestack CO2 before release. The initial build cost is put at about 2 to 3 million dollars, while a future commercial facility could cost between 100 and 200 million dollars and aim to capture up to 500,000 tons annually. The pilot will be grid-connected, and partners acknowledge that the process is energy-intensive and that grid power can mean continued fossil fuel use. Observers note that the pilot’s capture amounts are small compared with emissions from a large petrochemical complex in the area, but proponents see it as a realistic path to reduce some local pollution while supplying water.
Finance has been raised for a new desalination plant to be built about 60 kilometers west of a Middle Eastern capital. The project will be operated by a water-services company for 20 years on behalf of a national buyer. Total finance for the scheme reached about 130 million dollars, with roughly 70 percent expected from an export credit agency and local lending institutions and the remainder from a commercial bank. When complete, the plant will deliver about 100,000 cubic meters of water per day, and operators expect significant revenue over the life of the contract.
If ultrasonic desalination can be scaled, it could make sea sand a safer and more practical replacement for river sand in concrete production, lowering pressure on riverbeds and reducing environmental harm from sand mining. The combined DAC-desalination pilot shows how desalination plants and carbon-removal tech may be paired to serve industrial water demands while seeking to reduce CO2. Financing wins for large desalination plants indicate continued investment in water supply for industrial growth.
Important caveats remain: desalination and DAC are energy intensive, pilot CO2 capture rates are small relative to industrial emissions, and integrating new processes into industry raises questions about lifecycle emissions, water security, and long-term sustainability.
The main problem is salt trapped in the sand. Salt accelerates corrosion of steel reinforcement inside concrete, which weakens structures and shortens service life.
One commonly cited guideline recommends a maximum salt content of 0.04 percent for sand used as aggregate in reinforced concrete.
The method uses ultrasonic waves that create cavitation bubbles. When those bubbles collapse they dislodge salt and particles from sand grains, improving cleaning without direct mechanical contact.
Traditional sand washing can require about four tons of water per ton of sand. The ultrasonic process mixes sand and water at a 1:2 ratio by weight, which is about two tons of water per ton of sand, and claims additional water savings from faster and more effective cleaning.
It is a pilot that pairs seawater desalination with direct air capture. The plan is to use desalination brine in a process that produces a liquid sorbent to capture CO2, yielding fresh water and a mineralized form of CO2 as outputs.
Yes. Both desalination and DAC typically use significant energy, and if powered by grid electricity with fossil-fuel sources, the net climate benefits can be limited unless low-carbon power is used.
Key steps include scaling experiments to larger volumes, validating long-term effects on concrete durability, ensuring energy is supplied from low-carbon sources where possible, and evaluating cost and regulatory compliance for widespread use.
| Project | Purpose | Key technical points | Water use / Capacity | Cost / Finance | Environmental notes |
|---|---|---|---|---|---|
| Ultrasonic sea-sand desalination | Remove salt from sea sand for safe use in concrete | Cavitation-driven ultrasonic washing; 300 W or higher for ~3 minutes; 1:2 sand-to-water ratio; non-contact cleaning | Uses about 2 tons water per ton sand (mix 1:2) | Research-stage; published validation in a peer-reviewed journal | Reduces water use vs traditional washing; aims to meet 0.04% salt limit |
| Project Octopus (pilot) | Combine desalination and direct air capture to supply water and remove CO2 | Uses desalination brine to produce a liquid sorbent; mineralizes CO2 | Pilot provides fresh water as byproduct; capture target 500 t atmospheric + 500 t smokestack CO2 per year | Pilot cost ~ $2–3M; potential commercial cost $100–200M | Energy intensive; grid-connected pilot may rely on fossil-based power; aims to serve heavy industry |
| Barka 5 desalination plant | Large-scale desalination to supply industrial and public water needs | Design and long-term operation contract for 20 years | 100,000 cubic meters per day capacity | Approx. $130M financing secured; mixed export credit and commercial bank finance | Major new water supply; long-term revenue expected for operator |
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