Bacteria could be savior in Travis clean-up

Bacteria could be savior in Travis clean-up

Travis' Environmental Restoration Program has enlisted a new, very small ally in its war to clean up soil contaminated by solvents decades ago.

Actually, lots and lots of little allies -- naturally occurring bacteria that can break down those solvents.

The bacteria are a key component in an experimental contamination treatment process called a bioreactor which the base is now testing.

For years, the Air Force base has used a large network of wells to pump out contaminated groundwater that was then treated above ground.

As more and more groundwater was treated and most of the contamination was dealt with, it had become tougher to get to the residual contamination that has remained.

This was an especially tough problem for Travis because of a large amount of less-porous clay in the soil that traps the contamination. Regular pumps have a hard time reaching it.

'This is the hard stuff that drags on groundwater treatments for years and decades,' Anderson said. 'The solvents down there are really hard to pull out.'

Early last year, members of Travis' Environmental Restoration Program heard about an experimental way to leech out that remaining contamination called a bioreactor.

A solar-powered pump pulls contaminated water out of the ground which is sprayed over a buried chamber full of mulch and a mixture of gypsum and iron sand.

The decomposing mulch creates a population explosion in bacteria which breaks down the contamination in the water. Iron sulfide, created by the water and the iron sands, also helps the process.

'We are encouraging naturally growing bacteria to break down the contaminants,' Anderson said.

The water, which now has organic carbon from the mulch in it, percolates back into the soil. The carbon-rich water helps deal with contamination in the soil itself.

In summer 2010, Anderson and the other Restoration Program members will examine the bioreactor to see how much of a difference it has made in eliminating the contamination.

The bioreactor could potentially reduce the time taken to clean up contamination from decades to months. Given the fact it is solar-powered, the process would be more energy efficient and environmentally friendly.

'If it can work in this environment, it can work in a lot of places,'Anderson Said.