Aqueous solutions generated in mining, oil, gas, and other industries or operations involving boring a hole in the earth may comprise naphthenic acid which may need be removed. For example, water produced with oil from underground formations may comprise contaminants such as naphthenic acid. A source of an aqueous solution comprising naphthenic acid may be from most any borehole drilled in the earth's crust. Another source may be from contacting any type of water with petroleum, gas, coal (e.g., mining), etc. may lead to the formation of naphthenic acid.
Naphthenic acids are the major contaminant in water used for extraction of oil from tar sands. In the oil industry, after a hole is drilled, on-shore or offshore, oil and water come out of the borehole. The water may contain contaminants such as alcohol, aldehydes, and naphthenic acid. The alcohols and aldehydes may be bound to the naphthenic molecules forming naphthenic alcohols and naphthenic aldehydes. Therefore, an aqueous solution containing naphthenic aldehydes, naphthenic alcohols, and naphthenic acids may come from the borehole. The naphthenic acids contaminating aqueous solution may present environmental concerns with respect to discharging of the aqueous solution. Additionally, naphthenic aldehydes and naphthenic alcohols may be poisonous. Therefore, naphthenic aldehydes, naphthenic alcohols, and naphthenic acids need to be removed from the aqueous solution prior to discharge into the environment.
The naphthenic acids may have a solubility in the aqueous solution preventing removal by traditional oil-water separation methods. In the past, industry has transported the contaminated aqueous solution into manmade lakes or holding ponds. Over long periods of time, oxygen from the air may oxidize the naphthenic aldehyde and naphthenic alcohol into naphthenic acid and then the oxygen may oxidize the naphthenic acids into more environmentally friendly compounds.
However, this traditional approach in removing naphthenic aldehyde, naphthenic alcohol, and/or naphthenic acid may not be practical in many situations. For example, in offshore oil drilling it may not be practical to have a holding tank to provide the residence time for oxidation with oxygen in air as traditionally done. Other inadequacies of traditional methods may include increased stringency of governmental regulations on discharging and increasing water volume in the oil being produced.
Therefore, a need exists for improved processes and systems for removing naphthenic alcohol, naphthenic aldehyde, and naphthenic acid and other naphthenic compounds from an aqueous solution.