Slip Stream Filtration for Western Hemisphere’s Largest Cooling Tower


Near completion, the western hemisphere’s largest cooling tower, built for the Sasol USA Mega Project, required a temporary filtration system to treat water for the duration of the pre-commissioning passivation process. During pre-commissioning, the client would not have access to their WWTP as it was part of the newly constructed facility and not yet online. The passivation process would create high amounts of TSS in the water stream consisting of nearly eight million gallons of waterwhich would need to be treated in order to be re-used.  


Sasol and Rain for Rent had been in contact for over 2.5-years discussing the logistics of pre-commissioning, passivation, design, and flushing. After multiple bids and various engineered designs, Sasol agreed to partner with Rain for Rent on a slip stream filtration project design. Water was pulled from a Sabine River Authority canal and treated through 3rd party ultrafiltration units. Roughly eight-million gallons of filtered water was required to fill the cooling tower basin and the underground piping. The water circulated through several miles of underground piping and through each individual unit of the newly constructed chemical facility. Sasol and their chemical provider added passivation chemistry to this water stream for pre-commissioning purposes. Water returning to the cooling tower basin went through a 10,000 GPM slip stream filtration system to clarify solids flushed out of the lines.


  • This is the largest cooling tower in Western Hemisphere
  • Rain for Rent’s Sewer Water A-Team and Engineering Dept. collaborated with the local Rain for Rent Branch to provide the client with plans including quality CAD drawings and Google Earth overlays.   
  • A thorough pre-work Safety Plan was created for the site and project by a Rain for Rent Regional Safety Manager. 
  • Rain for Rent initially designed and bid the project with bag filtration that would step down the micron level as water was cleaned during circulation. The client requested sand media filtration instead, but that came with the risk of the media blinding if a chemical such as polyacrylamide was to be added, which was likely. Rain for Rent worked with the client to design a large change order that would fulfill their request and safely meet their needs by adding a full system of bag filters to polish the effluent water from sand filters. 
  • This two-stage system saved the customer money by reducing manpower and providing a filtration system that was more efficient than other bidders options.   
  • We provided and continue to provide start to finish service. The project is expected to last roughly one-year while all new units are brought online.   

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