REUSE of stripping effluents from nuclear power plant

CTP environnement set up a treatment solution that provided the customer with several reuse options:

• Recycling on an ultra-high pressure stripping unit with the following water quality constraints: T° < 30°C, pH 6-8, TSS < 5 ppm, COD < 20 ppm, metals < 5 ppm, conductivity < 1000 µS/cm²
• Refrigeration of pre-treated water
• Washing and rinsing water

Because of the high cost of disposal, it was impossible to discharge the effluent.
It was therefore necessary to treat the 250 m3 of hot, highly charged effluent from the stripping process on line and minimise its volume:

• TSS > 1 g/L,
• Metals > 100 mg/L,
• Lead >10 mg/L,
• COD > 100 mg/L

The recommended technical solution was as follows:

• Physico-chemical treatment (metal insolubilisation, coagulation, flocculation and decantation)
• Dewatering sludge in geotextile membranes 1 m³
• Filtration of clarified water, then adsorption on activated carbon
• Addition of plate heat exchanger cooling before GAC

The meticulous and frequent analytical monitoring, with a field laboratory, set up during the operation enabled:

• Adjustment and optimization of the treatment
• Demonstration of changes in the load and quality of treated water: T°, pH, COD, SS, metals, conductivity, etc.

The results were very positive, with effective treatment of the 250 m³ of reused effluent, resulting in:

• Treated water with a very significant reduction in suspended solids, metals, lead and COD, with stabilization of conductivity
• < 2 tons of solid sludge with a dryness of > 50 %
• < 50 m³ of water used vs. 250 m³, an 80 % saving
• 20 m³ of clarified effluent + 1 ton of solid waste eliminated

The total cost of the service, including waste disposal, has been cut in half compared with conventional effluent disposal.