Becoming liberated from the constraints of wastewater: SIKA invests in Clearcat vacuum distillation system

Current situation

After visiting the H2O stand at the Pollutec trade fair, SIKA France explained its requirements.

Manufacturing at the SIKA site in Gournay-en-Bray is carried out in tanks to which different reagents are added. To be able to move from one production process to the next, the tanks must be cleaned and rinsed with water. This rinse water is then stored in large tanks before being treated. It contains various pollutants such as hydrocarbons, salts and surfactants.

Treatment is currently carried out by evaporation and concentration using equipment dating from 2001 and the distillate is stored before being discharged to the municipal biological treatment plant. In accordance with the agreement entered into with the Gournay-en-Bray treatment plant, the wastewater is periodically inspected and analysed. The municipal plant accepts effluents in which the level of pollutants does not exceed a certain limit. As a last resort, non-compliant distillate must be eliminated in an authorised treatment plant, a very costly operation.

Launching the project

The search for a solution to replace the ageing evaporators involved several criteria:

• Partial recycling of the distillate initially, with the possibility of recycling all of it.
• Wastewater compliant with the prefectural order and within the limits imposed by the municipal treatment plant.
• Resistance to corrosion linked to chlorides.
• Easy maintenance and simple operation.
• Sufficient treatment capacity to treat all of the flow.

The Sika project team has drawn up a register of the loads, defining the quality of distillate necessary for recycling, whilst not ruling out the possibility of discharge into the municipal treatment plant. In addition, easy automated operation, as well as maintenance requiring few resources, were essential criteria when choosing a supplier.

Stages of the study

• Drawing up a full report on effluent flows and their corresponding volumes.
• Creation of a list of products used (lignosulfonates, carboxylates, gluconates and polymers). This part is crucial as it enables a list to be drawn up and products to be isolated whereby the flow may be critical.
• Performance of laboratory tests at H2O to determine the suitability of merging. During these tests we established that the effluents contained chlorides that are responsible for the corrosion of the existing evaporators. A special corrosion-resistant material therefore had to be taken into account: Uranus B6.
• Definition of the upstream and downstream storage capacities: the existing tanks had sufficient capacity.
• Definition of the post-treatment necessary to meet the quality requirements of the distillate: according to the distillation tests performed in the laboratory, no post-treatment is necessary to be able to respect the wastewater limits. However, for the recycling solution, it is preferable to pass the distillate over activated charcoal to reduce the COD.
• Definition of the average flow rate of the evaporator over the concentration factor obtained.

A VACUDEST 4,500 Clearcat evaporator, which can treat up to 15 m³/day with a concentration factor of 20, or 5% concentrate, meets this demand. Sika adopted this vacuum evaporation solution and decided to embark on the path towards zero liquid discharge and recycling of distillates. This means that Sika will no longer discharge water into the municipal treatment plant and will eventually be liberated from the constraints of wastewater control.

Vacutouch machine control panel. Optimum availability and easy operation of the system.

Operation and initial feedback

After two years in operation, the evaporator is producing some highly satisfactory results. In fact, Mr Montier, Head of Environment and Energy affirmed,

“Installation was very quick and the training comprehensive. We have been able to recycle the distillate as its quality allowed it. The H2O after-sales service is competent, attentive and responsive. They called us back within the hour or within 24 hours at most. An H2O technician needs calling out at least twice a year to ensure that the machine is working correctly.

In 2 years, we have only produced 160 tonnes of concentrate in a treatment capacity of 3,500 tonnes. This means that the return on investment will be less than 2 and a half years.”

Comparison with the naked eye of the distillate from a traditional vacuum evaporator with that from a VACUDEST with the Clearcat option shows that the integrated Clearcat oil separator represents true progress in terms of the quality of the treated wastewater.