Purification of effluents via membrane separation
An innovative process to purify your wastewater or effluent
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Historically, the treatment and/or purification of an effluent was carried out by classical physico-chemical processes such as adsorption, precipitation, ion exchange, etc. Separation of dissolved species of different sizes (e.g.: Na+ and UO22+) were only feasible through the above processes. To achieve the final goal, the different steps of the process could be complex and costly. Direct separation of two dissolved species was not possible by filtration, which consisted of separating only a liquid and a solid phase.
The membrane process is a relatively recent technology developed since the middle of the 20th century. New developments in the fields of materials science and engineering have led to the development of research on the subject. The principle is relatively simple: a supply solution comes into contact with a semi-permeable membrane, which acts as a filter. Large particles are retained, smaller elements pass through it. This process allows the separation of many elements of very different sizes. Particles of a few hundred µm by microfiltration with ions in the order of 2-3 Å by reverse osmosis. Thus, over the past ten years, many industrial separation processes have emerged in the mining, pharmaceutical, effluent treatment and drinking water treatment sectors... Aware of the prospects in this field, CIME has developed this process in all possible fields of application.- Reduced consumption of reagents
- Solution purification
- By-product recovery
- Process simplification
Laboratory tests have been conducted to confirm the possibility of using membrane technology to treat radiologically scarred effluents. The removal rates for uranium and radium were greater than 99.5% for two nanofiltration membranes. This process was transferred to the pilot scale, positioned on site. Lab results have been confirmed: several m3 of mine draining water were treated effectively. Uranium concentrations in the permeate were below the World Health Organisation (WHO) specifications of 30 µg/L.
Application at the Katco mine:
The objective of the membrane project at the Katco site was to assess the technical and economic feasibility of placing membranes on acid uranium eluates to separate sulphuric acid and uranium. The results showed that between 30 and 60% of the free acidity can be recovered in the permeate with, in parallel, uranium recovery rates of between 70 and 98%. This technology will be deployed onsite in 2019.
Application at the Trekkopje mine:
Membrane studies at the Trekkopje site were initiated in order to find a financially competitive solution for treating alkaline eluates and separating uranium and sodium bicarbonate. The objective was to reduce the overall costs of reagents to precipitate uranium. Laboratory and pilot-scale tests have shown that, of all the membranes tested, the DOW NF 270 membrane is the most effective for this problem. This process has not been defined on an industrial scale, the mine being placed in care and maintenance.
- Study of the process from laboratory to pilot scale
- Several test formats: from 100 mL to 1 m3
- Mobile pilot to work on site (20-foot container)
