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 The National Paint and Coatings Association – International Marine and Offshore Coatings Conference: Virginia Beach, VA. June 5 to June 7, 2000Development of a Technology to Remove TBT (tributyltin) from Shipyard Wastewater
– Thomas Fox, CASRM  Virginia Beach, VA, June 7
– Last September, CQD Journal for the Maritime Environment Industry reported on
Thomas Fox's work with CASRM
. At that time Fox and his team were in the process of helping shipyards and drydocks in the Commonwealth of Virginia attempt to meet severe state restrictions on TBT in wastewater of
under 50 parts per trillion (ppt). Since then Fox's group has had great success and NPCA members were given a full update. The first problem, Fox explained, was the pressing need for a rapid TBT analysis method. Currently accepted TBT analysis is by commercial laboratories that produce an answer in
about two weeks. The coming ban of TBT worldwide and the inability to detain a ship in port for a lengthy period of time means rapid TBT analysis is sorely needed. Using a method
established by Dr. Greg Cutter, the CASRM team has developed a means of measuring TBT levels as low as 6 parts per trillion (ppt) in wastewater within eight minutes. The new
method is expected to be less costly as well, mentions Fox.
The lab and pilot programs to remove TBT have also been progressing well, says Fox.
In the lab, the CASRM team has had success in removing TBT traces from one million ppt down to 6 ppt. CASRM has also created a barge mounted pilot treatment plant for TBT. The 140 ft
barge carries 4 tanks with 20,000 gal. capacity. Fox explained the pilot plant is capable of treating a rate of 100 gals/minute to levels below the 50 ppt discharge limit.
The advantage of the barge, said Fox, is the ability to move the plant from shipyard to shipyard as different jobs require. Not all vessels come into U.S. shipyards with TBT on
their hulls, so the barge makes it easy for the team to treat multiple facilities. Fox points out that yard permits are now tied to the barge which has its own discharge permit.
Fox says the big worry for the CASRM project at this time is the treatment system is pulling out more then just TBT from the wastewater. A lot of dissolved organics are
present in the water as well, which load up the system. This makes treatment more expensive since the activated carbon columns must be replaced more often. He says
the barge charges about $40,000/ship currently, but he is hoping by the time the pilot program is finished, they will be able to treat at $5,000/ship.
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