Common uranium salts in water and removal/purification technologies

Uranium measured in water is usually reported as total uranium, not as a single dissolved salt. Its aqueous form depends on oxidation-reduction conditions, pH and ligands such as carbonate, hydroxide, sulfate and phosphate. These factors affect mobility and the treatment process that may work.

For uranium-bearing groundwater, mining water or process brine, treatment selection starts with a representative analysis and an understanding of uranium speciation. Treatment also needs a plan for managing uranium-containing concentrates, spent media and sludge.

Common uranium species and compounds in water

The table separates dissolved aqueous species from solid minerals and process chemicals. Finding uranium in a sample does not by itself show that a named salt is present: analytical results are generally reported as total uranium (U).

Species or compound	Formula or representative form	Typical water or process context	Water behaviour
Uranyl–carbonate complexes	UO₂CO₃(aq), UO₂(CO₃)₂²⁻, UO₂(CO₃)₃⁴⁻; calcium–uranyl–carbonate complexes can also form	Oxic groundwater with bicarbonate/carbonate alkalinity; some alkaline mine waters	Often soluble and mobile. The distribution among species depends on pH, carbonate, calcium and ionic strength; it is not a fixed “uranium carbonate salt” concentration.
Uranyl hydrolysis species	UO₂²⁺ and hydrolysed forms such as UO₂OH⁺ or neutral hydroxo complexes	Oxic waters where carbonate is limited, with the exact forms changing with pH	Speciation changes as pH changes; hydrolysis, sorption and precipitation can affect dissolved uranium.
Uranyl–sulfate complexes	For example, UO₂SO₄(aq) and higher sulfate complexes	Acidic sulfate-rich mine drainage, uranium leach solutions and metallurgical process waters	Complexes can keep U(VI) in solution. Concentration and speciation depend on acidity, sulfate and other ions.
Uranyl–phosphate species and uranium-phosphate minerals	Aqueous uranyl–phosphate complexes; solids include autunite-group minerals	Phosphate-bearing groundwater, sediments and waters affected by phosphate treatment or uranium-bearing minerals	Phosphate can complex uranium and, under suitable conditions, form low-solubility solids. Outcomes depend on pH and competing ions; a mineral formula should not be mistaken for a dissolved salt.
Uranyl nitrate	UO₂(NO₃)₂ (often hydrated)	Laboratory, nuclear-fuel-cycle and specialized chemical process solutions; not a typical naturally occurring groundwater salt	Readily soluble as a process chemical. Once dissolved, uranium speciation depends on the solution chemistry rather than remaining solely as intact uranyl nitrate.
Uranium(IV) oxide and silicate minerals	UO₂(s) (uraninite); USiO₄(s) (coffinite)	Reducing aquifers, sediments, ore zones and mine residues	Generally sparingly soluble under reducing conditions, though oxidation and changing water chemistry can mobilize uranium.
Uranium concentrates and precipitated process products	Composition varies; commonly uranium oxides or uranium-bearing precipitates	Mining and uranium-processing circuits, residues and tailings	These are solids, not common dissolved salts in ordinary water. Dust, leachate or process-water contact may create uranium-bearing water that requires assessment.

Key point: Under oxidizing conditions, U(VI) commonly forms uranyl complexes. Carbonate and hydroxide are major ligands in many groundwaters; sulfate, phosphate, fluoride and organic matter may also influence speciation. Under reducing conditions, U(IV) solids are often less soluble. See the USGS review of uranium speciation in groundwater and its study of uranium and other elements in groundwater.

Uranium removal, separation and purification options

Objective	Potential technology	Selection considerations
Remove dissolved uranium from groundwater	Anion exchange	Can be effective for negatively charged uranyl–carbonate complexes. Resin selection, alkalinity, sulfate, nitrate and other competing ions affect capacity and breakthrough; regeneration creates a uranium-bearing brine.
Reduce uranium and other dissolved ions	Reverse osmosis (RO) or nanofiltration (NF)	Membrane separation can reduce dissolved uranium, but performance depends on membrane, speciation and feed chemistry. The concentrate contains rejected constituents and requires managed handling.
Capture uranium with solids for subsequent separation	Coagulation, adsorption and filtration using suitable iron- or aluminium-based treatment	Removal depends on pH, coagulant dose, uranium form and water matrix. Bench testing is needed; the resulting sludge or filter backwash may contain concentrated uranium.
Remove uranium during hardness treatment	Lime softening or lime-soda softening	May co-precipitate uranium under appropriate conditions, but performance is variable and strongly dependent on pH and source-water composition. Residual sludge needs appropriate management.
Recover uranium from mining or process solutions	Ion exchange, solvent extraction and controlled precipitation	These are established hydrometallurgical process steps in suitable circuits. They require process-specific design, safety controls and management of uranium-bearing products and residuals; they are not interchangeable with household drinking-water treatment.

WHO and the U.S. EPA identify treatment approaches that include ion exchange, reverse osmosis, coagulation/filtration and lime softening. Their performance varies with feedwater chemistry and process operation. Confirm treatment with representative testing and monitor both finished water and residual streams. For uranium-specific drinking-water considerations, see the WHO uranium fact sheet and the U.S. EPA guidance on treatment residuals.

Discuss a water-treatment challenge

For a specific uranium-bearing water or process stream, treatment options should be assessed against its analysis, target quality and residual-management requirements.

Last reviewed: 9 November 2026 by Lenntech.

Sources and further reading

Request a quote

Phone: +31 152 610 900
info@lenntech.com

Request a quote