Crews added living microbes to the Pueblo Chemical Agent-Destruction Pilot Plant (PCAPP) biotreatment system, and began processing hydrolysate, the product of the mustard agent neutralization process, April 19.

“Immobilized Cell Bioreactor seeding began on Monday. Seeding means we added biomass to ICB modules one and two,” said Dr. James Earley, chief scientist, PCAPP.

“We are using microorganisms commonly found in nature to treat the hydrolysate,” said Earley. “Active biomass is needed to degrade the hydrolysate.”

In basic terms, the microbes will ingest the thiodiglycol (TDG) in the hydrolysate and break it down into sulfuric acid, carbon dioxide and water. The sulfuric acid is neutralized by the addition of caustic to the bioreactors, Earley said.

“During start-up and acclimation, our objective is to increase the number of TDG degrading microbes in the bioreactors in order to operate the plant as efficiently and effectively as possible,” Earley said.

In the course of two days, microbes from the local wastewater treatment plant were added to module two. On the third day, the module was batch fed with hydrolysate to give an initial TDG concentration of approximately 500 milligrams per liter in each of the four ICB reactors in the module. The same protocol will apply for the first module, Earley said.

“We will progressively increase the initial concentration of TDG as the biomass becomes more active, which further increases the activity,” Earley said. “Our goal is to increase the population of TDG degrading microorganisms to increase throughput.”