Suspended Solids (un-dissolved/insoluble)
Floating Materials (mainly FOG)
Dissolved (soluble) Impurities
Volatile Organics (VOC)
Biodegradable Compounds (BOD; FOG)
Refractory or Persistent (eg. Phenols)
Metals (as salts)
Nutrients (N, P)
Sulfur (as -SO4, S-)
Color (can be colloidal or dissolved)
Crude Oil Impurites
Since the types of waste generated from crude oil processing is accompanied with the crude oil, a discussion of these impurities is included. All crude oil contains impurities which contribute to corrosion, heat exchanger fouling, furnace coking, catalyst deactivation and product degradation. These contaminants are broadly characterized as salts, BS&W, solids, and metals. The amounts of these impurities vary for different crudes. Generally, crude oil salt content ranges between 3 and 200 pounds per 1,000 barrels (ptb). Bottom sediment and water (BS&W) averages about 0.25 volume percent. Solids content typically varies between 5 and 100 ptb.
Crude oil brine analysis varies, with 75 percent sodium chloride, 15 percent magnesium chloride, and 10 percent calcium chloride considered average. Chloride salts are the source of hydrogen chloride that is evolved during distillation. Magnesium chloride is the most prolific producer of HCI with calcium chloride and sodium chloride ranking second and third, respectively, in HCl production. As the concentration of a chloride decreases, the evolution rate diminishes, but the proportion of chloride converted to HCl increases. The presence of organic acids and other impurities intensifies HCI generation.
Carbonates and Sulfates 2
These salts are sometimes present in concentrations that equal or exceed the chloride concentration in the brine. Carbonates and particularly sulfates may be present in sufficient quantity to promote crude preheat exchanger...