Sludge clearing and dewatering for a final ATEX zone tank

Our client, a major player in the refining industry, asked CTP environnement to clear out the final tank located close to their plant. The discharged effluent had created a build-up of sludge at the bottom of the tank of around 120 m³ (157 yd³) with 35 % dryness (estimate for an area of 200 m² /2153 ft²).

After draining and treating the supernatant water, the sludge accumulated at the bottom of the tank needed to be cleared and dewatered.

CTP environnement suggested implementing a cost-effective solution in terms of mechanical equipment, which was quick and easy to set up. Dewatering using the Geofloc^® process combined with geotextile membranes has indeed various advantages:

• High clearing speeds
• Low energy consumption
• Treatment and safe storage in the same facility

On the basis of the data provided by the client, two 58 m³ (76 yd³) filtering storage tanks were installed and supplied by two pneumatic pumps and a Geofloc^® online flocculation unit. Thanks to their design, these geotextile membranes allowed the sludge to continue drying after draining. Samples of this sludge were taken regularly to assess the quality of the treatment and to monitor the change in dryness over time.

Despite significant safety constraints and adverse weather conditions, treatment went well. Excellent cooperation between the client’s and CTP environnement’s teams allowed work to be carried out in the best possible safety conditions and in a climate of trust, while adhering to commitments in relation to results, time and cost (2 to 3 times less expensive than a standard solution).