June 1996 Issues Online June 2007 April 2007 February 2007 December 2006 October 2006 August 2006 June 2006 April 2006 February 2006 December 2005 October 2005 August 2005 June 2005 April 2005 February 2005 December 2004 October 2004 August 2004 June 2004 April 2004 February 2004 December 2003 October 2003 August 2003 June 2003 April 2003 February 2003 December 2002 October 2002 August 2002 June 2002 April 2002 February 2002 December 2001 October 2001 August 2001 June 2001 April 2001 February 2001 December 2000 October 2000 August 2000 June 2000 April 2000 February 2000 December 1999 October 1999 August 1999 June 1999 April 1999 February 1999 December 1998 October 1998 August 1998 June 1998 April 1998 February 1998 December 1997 October 1997 August 1997 June 1997 April 1997 February 1997 December 1996 October 1996 August 1996 June 1996 April 1996 February 1996 December 1995 October 1995 August 1995 June 1995 April 1995 February 1995 December 1994 October 1994 August 1994 June 1994 April 1994 February 1994 December 1993 October 1993 August 1993 Select any issue from the menu in this bar.

Refineries Research Selenium Disposal

Unocal, Shell, and Exxon are taking three different paths toward what hopefully will be a common destination - a significant reduction of selenium flowing from their refineries into the Bay. Under terms of an out of court settlement with state regulators, the three oil companies agreed to reduce selenium discharge levels to 50 ppb by July 1998. The type of selenium - called selenite - discharged by the North Bay oil industry bioaccumulates in the food chain four times faster than the stuff coming downriver from the selenium-rich soils in agricultural areas upstream. But at the time of the settlement, no technology existed that would allow the oil companies to reach the reduction goal.

The refineries (along with three others that were already in compliance) undertook a joint study to identify potential selenium reduction methods. That study was completed last summer, and the three are now engaged in separate pilot testing programs.

Each refinery is using a proprietary approach it believes best fits its own circumstances. Exxon is developing a "reverse osmosis" technology, removing the selenium with a membrane filter, then feeding the waste products into a fluid coker. This bonds the selenium with coke, which then can hopefully be used as a fuel.

Unocal is testing an "ion exchange" method, circulating contaminated wastewater through a column packed with resin. As water flows through the column, selenium ions replace chloride ions on the outside of the resin beads. The refinery estimates that the process will generate 500-600 pounds of solid waste a day, which would contain about five pounds of actual selenium. Unocal engineer Marjorie Hatter says that the fact the process "is real specific to selenium," doesn't need wastewater ponds, and produces relatively small amount of solid waste make it especially suitable for the Rodeo refinery.

Shell is redesigning its refinery in order to meet the state's clean fuels guidelines, and is pilot testing new wastewater treatment systems. It is also testing an iron coprecipitation-based control measure, in which iron particles bond with the selenium. The sludge, which contains selenium by products, is then treated as a hazardous waste product.

The S.F. Regional Board's Kim Taylor says the new technologies look "promising," although there are "still bugs to be worked out." Once the pilot tests are completed, the refineries will design and build full scale systems.

Taylor says the Board is "satisfied that all three refineries are complying" with the settlement, but environmentalists aren't so sure. They want board members to impose specific timelines for completion of the pilot tests and implementation of the new processes. They point out that high selenium levels have been found in Bay seals, birds and fish, and they fear that the substance could cause genetic and reproductive problems like those found in waterfowl living in the polluted Kesterson Refuge. "We believe that some assurances are needed," says BayKeeper's Mike Lozeau.

Contact: Kim Taylor (510)286-3821

«To @@(newsletter_title)@@ Index