Module 2: Refinery Processes & Units
Process Water: Four Sources of Refinery Wastewater
"Process Water" is a category of refinery wastewater loosely defined as water that has been in intimate contact with hydrocarbons. [1]
Four Major Sources
Desalter effluent comes from the desalting unit, which washes salts out of crude oil before processing. Corrosion will occur more rapidly if salts are not removed. Sour water is water containing hydrogen sulfide and ammonia: it is typically routed first to sour water strippers and then to wastewater treatment. Tank bottom draws come from crude storage tanks, where Bottom Sediment and Water (BS&W) settles and must be removed periodically. Spent caustic is formed from the extraction of acidic components, such as hydrogen sulfide, from hydrocarbon streams. Routing to wastewater is one option for disposal, though off-site disposal may be more economical. [1]
Common Contaminants
Process water contaminants include free hydrocarbons, sulfides, ammonia, and suspended solids.