Petroleum hydrocarbons suspended solids

Since desalting is a closed process, there is little potential for exposure to the feedstock unless a leak or release occurs. However, whenever elevated temperatures are used when desalting sour (sulfur-containing) petroleum, hydrogen sulfide will be present. Depending on the crude feedstock and the treatment chemicals used, the wastewater will contain varying amounts of chlorides, sulfides, bicarbonates, ammonia, hydrocarbons, phenol, and suspended solids. If diatoma-ceous earth is used in filtration, exposures should be minimized or controlled. 

Petroleum hydrocarbons, either dissolved, emulsified, or occurring as free-phase, will be the key constitnents, although wastewater may also contain significant concentrations of phenols, amines, amides, alcohols, ammonia, sulfide, heavy metals, and suspended solids. 

In aquatic environments, the heavier and less vola-tile/soluble compounds in crude oil will adsorb to suspended solids and subsequently settle in the sediments. Some heavy fractions with high density may sink into the sediment. This happens after the initial removal of the smaller and more volatile chemicals by either dissolution or volatilization. This is followed by biodegradation of those crude oil constituents that can serve as a food source for bacteria. Biodegradation is a significant mechanism for removal of hydrocarbons released into the environment. However, this generally occurs on the order of months and years. It is not believed that there is significant bioaccumulation of petroleum hydrocarbons in aquatic organisms. 

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