CASRM BARGE SUPPORTS WASTEWATER TREATMENT FACILITY
New environmental standards set by the commonwealth of Virginia will soon make shipyards work harder to remove tributylin (TBT) from their wastewater. And with the help of Old Dominion's Center for Advanced Ship Repair and Maintenance (CASRM), shipyards soon will set a national precedent for TBT reduction.
A year ago, CASRM received a $4.28 million grant from the state's Department of Environmental Quality and the Environmental Protection Agency to help Virginia shipyards eliminate TBT waste. These funds followed on the heels of new
environmental regulations requiring shipyards to reduce the levels of TBT -- a chemical used in the paint on ship hulls -- in their wastewater.
Using the grant monies, CASRM built a pilot wastewater treatment facility aboard a floating barge. The 100-foot by 60-foot barge can move to various shipyards in Hampton Roads, including Newport News Shipbuilding and the Norfolk Naval Shipyard.
CASRM is a partnership between Old Dominion, Virginia's Center for Innovative Technology, the city of Norfolk and the South Tidewater Association of Ship Repairers, which includes all of the private shipyards having operations in the Norfolk/Newport News area.
Its overall objective, says director Tom Fox, is to focus on shipyard problems, including finding ways to meet or exceed environmental requirements while remaining cost effective.
CASRM's barge-mounted TBT pilot plant began operating in December, treating two 20,000-gallon batches of TBT wastewater. The test run proved successful. The influent TBT levels are the lowest so far observed using activated carbon and are well under environmental limits, according to Fox.
TBT poses a serious environmental threat to waterways and marine life, he explained. It is used in paint to keep marine life from attaching to the ships' bottoms. According to Fox, many ships continue using the paint for this reason. When marine organisms stick to the bottom, the ships' fuel efficiency decreases. "The paint makes the surface slippery, so barnacles cannot attach themselves, and with less friction there is better fuel efficiency," Fox explained.
The Navy, which stopped using TBT in paint several years ago, spends about $150 million on fuel each year.
While the International Maritime Organization soon may call for a global ban, many ships have not stopped using the TBT-based paint. And even once they do, shipyards still will be dealing with the issue when ships come in for overhaul, repainting and repair. About 28,000 large vessels with TBT-painted hulls are in use today.
Although TBT leeches into waterways continuously at an alarming rate, TBT wastewater is more concentrated when ships are being cleaned and repainted, posing an even greater environmental risk.
While harbor traffic cannot be regulated, shipyards can, said Fox.
"If ships don't want to use these shipyards, they can go up to Baltimore or Jacksonville, where the wastewater is then put straight back into the waterways without treatment," said CASRM's director, who has already received inquiries from Australia and Germany about the new treatment facility.
To treat a ship that is being cleaned or repainted, the barge is tied to the pier near the ship's drydock. The shipyard is responsible for pumping the wash water onto the barge, where 100,000 gallons -- roughly the same amount of wastewater from one large ship -- can be stored and filtered. The shipyard supplies the power, air and water.
Instead of being added back to Hampton Roads waterways, the water that is used to clean the hull is pumped into four storage tanks aboard the barge, which can store and filter thousands of gallons of TBT-contaminated wastewater.
Two Old Dominion researchers have played a significant role in the operation: Gary Schafran, associate professor of civil and environmental engineering, and Greg Cutter, professor of ocean, earth and atmospheric sciences.
It was Cutter's ingenuity that led to the development of a faster method to measure TBT. His new method offers the CASRM project team opportunities to explore numerous operational conditions with the pilot plant and evaluate other treatment technologies such as chemical oxidizers that may be needed to exceed the 50 parts per trillion standard.
Schafran conducted a variety of treatability studies, determining that it was indeed possible to take TBT out of the wash water.
Aboard the barge, Schafran oversees treatment of the contaminated water, which is turned into a clear solution and discharged back into the waterway.
Schafran's process, which utilizes a combination of coagulates, pH additives and activated carbon filters to clean the wastewater, can currently reduce 1 million parts TBT per trillion to 50 parts per trillion, which is the state standard. The goal, Schafran said, is to be below 50 parts per trillion consistently.
This article was posted on: April 27, 2000
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