Introduction to Electrokinetics - Electrokinetics for Petroleum and Environmental Engineers - page 16

of 18,000 sq. ft. and penetrated to the depth of about 15 ft. The total volume
of spill was estimated at 300,000 gallons. The initial concentration of gaso-
line in the plume averaged about 40 mg/l of total BTEX (Benzene, Toluene,
Ethylbenzene, and Xylenes).
A special enhanced bioremediation system was designed to clean this
site. The system consisted of two groundwater recovery wells, a treatment
unit and an infiltration gallery. The treatment unit consisted of transfer
pumps, pressure filters, granulated activated carbon filters, air spray-
ers, holding tanks, chemical feed system, water heater and monitoring
means. The bioenhancement process included heating, addition of nutri-
ent amendments (monoammonium phosphate and trisodium phosphate),
and oxygen addition (dilute hydrogen peroxide). In six months of opera-
tions, BTEX in the plume had been reduced to a level less than 6.5 mg/l
with the passage of 11 pore volumes of displacement.

1.8 Electrical Enhanced Oil Recovery (EEOR)

In 1952, Tchilingarian (Chilingar) suggested the possibility of using direct
electric current for the separation of fine sediments into grades on the basis
of different cataphoretic velocity exhibited by clay particles of different
size. This was achieved on treatment of clays with NaOH, because OH - ions
impart greater negative change to clays and, consequently, greater veloc-
ity towards the positive electrode. He started this research because he was
questioning the statement in textbooks that “cataphoretic velocity is inde-
pendent of size and shape of colloids”. Also, knowing the success in dewa-
tering of clays by soil engineers, he started research on EEOR together with
his students at the Petroleum Engineering Laboratories of the University of
Southern California (e.g., Anbah, 1963).
Chilingar and his students (Ace, 1955; Anbah et al., 1964, 1965; Chilingar
et al., 1968a,b, 1970,1997) conducted numerous laboratory tests involving
electrokinetics since the 1950s, which indicated that this low-power drain
mechanism could be used for EOR. Tikhomolova (1993) described similar
studies conducted at the University of St. Petersburg, also suggesting elec-
trokinetics as a potential EOR technology. Hill (1997) conducted bench-
scale studies, which suggested that hydrocarbons could be transported
via electrokinetic mechanisms. Pamukcu et al. (1993) and her students at
Lehigh University, demonstrated electrokinetic transport of hydrocarbons
(PAH), in clay-rich soils, as a method of remediating manufactured gas
plant site contamination.