Malvési

Treatment of liquid effluents and rainwater 
All liquid effluents generated during the conversion process are treated inside the facilities dedicated to recovering the natural uranium. They are then transferred to settling and evaporating ponds. Rainwater is also collected, stored in rainwater basins, controlled and treated by osmosis and evaporation, before being releases into the Tauran canal. 

Limiting and controlling atmospheric releases 
To limit atmospheric releases, stacks are equipped with purification and measuring systems. The gases are cleaned and purified by passing through scrubbing columns before being released into the environment. 

Developments designed to reduce risks 

To reduce its environmental footprint, Orano Malvesi has invested nearly 500 million euros over 10 years to renew its industrial facilities and to secure and reinforce the structures in the lagooning area. 

Securing the lagooning area 

Further to the undertakings made following the breach of a dike in one of the site's settling ponds in 2004, and the severe weather events of 2006, a major investment program was carried out from 2004 to 2013 to secure and reinforce the structures in the lagooning treatment area. Other work was also carried out on the site to reduce water withdrawals and discharges into the environment, in particular through further improvements, including the creation of an efficient management system for collected water and the creation of a closed-loop cooling water system. With these major works already completed, the entire lagoon area has been revamped, enhancing the safety of the ponds: 

• Reinforcement of the dikes 
  
• Reduction of the environmental footprint with the construction of an underground wall to capture groundwater for monitoring and analysis before release into the natural environment 
  
• Reinforcement of the mechanisms for periodic monitoring of the stability of the dikes: survey markers, piezometers for measuring the water level in the dikes and inclinometers.

With TDN, a waste product that meets the requirements of final disposal channels 

Treating the nitrated liquid effluents resulting from the natural uranium conversion stage is the great challenge for the future TDN (Traitement Des Nitrates) nitrates treatment facility at the Malvési industrial site.  

Since the beginning of the conversion activity in the early 1960s, the processes used with the mining concentrates have produced nitrate-laden liquid effluents, which undergo various treatments.  
These effluents first go through a settling stage in specific ponds and then an evaporation stage in further ponds (lagoons). Today, the storage ponds contain 350,000 m3 of nitrate-bearing liquid effluents.  

The implementation of the TDN facility will lead to the following benefits in the treatment of these effluents:  

• resolve the liability by eventually eliminating the evaporation ponds;  
  
• secure the site against a major local "cévenol" rainfall event;  
  
• destroy the nitrates and create a very low-level waste (VLLW) suitable for final disposal and meeting ANDRA's acceptance criteria for its Aube facility, where this type of waste will be accommodated over the very long term in France.  

Twenty-five years of R&D and 10 million euros were needed to identify the treatment process adapted to the challenges of the Orano Malvési plant and the specific nature of the nitrates. More than fifteen solutions were looked into before the teams made their selection of a process developed for the US Department of Energy (DOE) by the company Studsvik in Colorado.  
The process used is one of steam reforming, which reduces nitrates to nitrogen and produces a smaller volume of solid waste (volume reduced by a factor of 3). This waste, which is chemically inert, can then be sent to the approved VLLW (Very Low Level Waste) disposal channel.  
In terms of releases, the process used in TDN has no significant impact on the environment and no health impact. Atmospheric emissions are well below the limit values set by the authorities and will comply with their requirements in all respects. In particular:  

• TDN emissions are composed of more than 90% of nitrogen, oxygen and water vapor;  
  
• Nitrogen oxides (NOx) represent only 0.02% of TDN emissions. 
  

In total, the Malvési facility will have reduced NOx emissions by 70% in 7 years, taking future TDN emissions into account. This investment is a demonstration of the site's commitment to reducing its environmental footprint.  

On November 8, 2017, the Prefect of the Aude department authorized the implementation of the TDN facility by prefectoral decree following a favorable opinion from the CODERST (the department's Council for Environment, Health and Technological Risks) dated October 13, 2017. Prior to that, in accordance with statutory process, a public inquiry was held in 2016 to allow all persons to become acquainted with the project and express their views on its content. It concluded with a favorable opinion from the Investigating Commissioner. In 2019, the final engineering studies were completed before work began.