Prince William Sound Regional Citizens’ Advisory Council ~ Citizens promoting environmentally safe operation of the Al yeska terminal and associated tankers. VALDEZ: PO Box 3089 / 130 S. Meals, Ste. 202, Valdez AK 99686 ~ toll-free: 877.478.7221 ph: 907.834.5000 fax: 907.835.5926 ANCHORAGE: 3709 Spenard Rd., Ste. 100, Anchorage, AK 99503 ~ toll-free: 800.478.7221 ph: 907.277.7222 fax: 907.277.4523 www.pwsrcac.org ~ see other PWSRCAC fact sheets at www.pwsrcac.org/resources/factsheet.html **FACT SHEET** 

# Ballast Water Treatment Facility February 2007

Overview The Ballast Water Treatment Facility at the Valdez tanker terminal processes “dirty” ballast—seawater stored in the cargo tanks of empty oil tankers for stability on the open ocean. When tankers arrive in Valdez to load oil, they must first offload oily ballast water. At the ballast water facility, the oil and water are separated. The recovered oil is put back into the system and loaded onto tankers as cargo, while the treated water is discharged into Port Valdez. Treatment is a three-stage process.

see also: www.pwsrcac.org/projects/TermOps/bwtf.html www.pwsrcac.org/projects/TermOps/airqual.html www.pwsrcac.org/newsroom/bwtfads.html Air Pollution Air emissions from the ballast wa

ter treatment facility are currently unregulated, yet they greatly exceed the threshold at which the Environ

mental Protection Agency deems a facility a major source of hazardous air emissions. The council continues to monitor this issue and to vigor

ously support reduction of hazard

ous air emissions from the facility. 

# Stage 1: GRAVITY SEPARA

TION . Oily ballast water and other facility waste water is pumped into large gravity separation tanks (also called 90s tanks) where the oil floats to the surface. That oil is then skimmed off, stored in recovered crude oil tanks (also called 80s tanks) and eventually loaded onto tankers as cargo.

Gravity separation tanks. 

# Stage 2: DISSOLVED AIR FLO

TATION . Next, waste water is routed into dissolved air flotation (DAF) cells for further removal of hydrocarbons. Air and polymers are introduced and dissolved into the waste water under pressure as it is piped to the DAF cells. Release of the pressure as the water en

ters the DAF cells causes the formation of very tiny bubbles that accelerate the process of separating the remaining oil droplets from the water. The polymer binds the oil together, while tiny air bubbles float the polymerized oil to the surface. Oil recovered at this stage is also reloaded as cargo.

Dissolved air flotation cells. 

# Stage 3: BIOLOGICAL TREAT

MENT . Waste water from the DAF cells is sent to biological treatment tanks for the final stage of hydrocarbon removal. Oil-consuming microbes and volatiliza

tion to atmosphere removes additional hydrocarbons including certain aro

matic hydrocarbons known as BTEX (benzene, toluene, ethylbenzene, and xylene). Benzene is a known human carcinogen. The hydrocarbon content of the treated water discharged into Port Valdez is strictly regulated by a federal permit.

Biological treatment tank.



### Alyeska Pipeline Service Co. is in the process of substantially upgrading and redesigning this facility to reduce air and water pollution.