Oil Water separator: Bypass & treatment of polluted waste stream

Challenge:
Whilst maintenance was carried out on a customer’s oil/water separator, the system needed to be bypassed to allow the continuation of production. 

Pollution such as oil , benzene and naptha resulting from several different processes is contained  within the customer’s tank containment areas and normally fed into the oil/water separator after rainfall or cleaning. 
As the containment/bunding is made of concrete, particles  such as small stones, grid and sand are contained in the wastestream.

These particles, along with the rainwater and oil, needed to be separated from the waste stream so no polluted water would be discharged towards surface water and the process of removing heavy metals (using Activated Carbon) was unaffected.

Solution:  
United Rentals engineered a solution to treat the polluted waste consisting of the following:

• Separation tanks were installed to receive the influent stream which differed in composition and capacity. The tank allowed larger particles to settle and the stream could be handled continuously and homogeneously.
• An oil skimmer was placed within the separation tanks to skim off the fastest floating oil layer.
• A Bag Filter system was used as a strainer,  capturing particles up to 6 mm to protect the Lamella filter tank from clogging.
• For the further filtration of slower floating oil and particles, a Lamella filter tank was installed.
• 6” ATEX Electric Centrifugal pumps are installed with automatic start/stop for the transfer of liquids through the filtration system.
• For further treatment, a 4” Electric Eccentric Screw Pump transferred the sludge for dewatering or disposal.

Benefits: 
Thanks to the integrated treatment solution, the filtration system bypassed the existing Oil/Water separator which resulted in no production losses during maintenance and significant cost savings due to limited downtime. 

Due to this filtration solution, oil, sand, stones and grit were removed resulting in more cost and handling savings, as the treatment step to remove heavy metals (using Activated Carbon) was not overloaded and no additional change-outs where needed.

The United Rentals ATEX pumps meant the installation of the treatment solution was safe and adaptable within ATEX zones ensuring safety as the top priority.