Making the Pueblo Chemical Agent-Destruction Pilot Plant, or PCAPP, biotreatment system work the way it is intended is a key priority for Army leaders overseeing the project.
The PCAPP facility will destroy Pueblo Chemical Depot’s stockpile of mustard agent by neutralization coupled with biotreatment and brine reduction systems for water recovery — systems that have never been previously operated together at a full-scale level to destroy chemical weapons.
Surrogate testing of the biotreatment system, which began in early June, is currently ongoing with favorable results so far. The bioreactors are being tested with pure thiodiglycol, the primary component of mustard agent hydrolysate. Preliminary results showed greater than 99 percent thiodiglycol removal efficiencies during batch and initial continuous flow operations, reports Dr. Yakup Nurdogan, cognizant system engineer, PCAPP.
During actual plant operations, the hydrolysate produced by mustard agent neutralization may affect the biotreatment process differently than the pure thiodiglycol being used in testing.
Planning for this contingency is currently underway and is integral in ensuring potential biotreatment issues do not interrupt the pace of chemical weapons destruction, said Greg Mohrman, PCAPP site project manager.
“The planning is being conducted early to ensure successful plant operations if, for some reason, the biotreatment system fails to perform as designed,” Mohrman said. “We fully expect it to effectively destroy mustard agent hydrolysate as it is designed to do, and the National Academies of Sciences supports that expectation.”
“We want to prevent any future shortfalls in the biotreatment area that may impact chemical weapons destruction,” said Conrad Whyne, Assembled Chemical Weapons Alternatives program executive officer.
Once the plant is operational, the biotreatment system will process mustard hydrolysate for a minimum of six months to allow for sufficient time and data to assess whether it is working as designed, or if it is negatively impacting chemical agent destruction, Whyne said.
There will be a slow ramp-up before the first mustard hydrolysate is produced. Once plant operations begin, it will take approximately 10 weeks before enough hydrolysate is accumulated to start feeding the biotreatment area, Whyne said. Data will then be collected and analyzed for six months to determine how well the process is working and, if necessary, to develop the most practical path forward to ensure the uninterrupted destruction of the chemical weapons stockpile.
If the biotreatment process fails during operations, the plant can accommodate up to 30 days of hydrolysate storage, Mohrman said. If this happens, and the plant’s hydrolysate storage capacity is maxed out with no other contingencies in place, the plant cannot continue operating until alternate means of hydrolysate storage or treatment are implemented.
“Because the National Environmental Policy Act permitting process can be lengthy, we have started the process now in case it is needed in the future,” Mohrman said. “We have begun data collection, analyzing decision pathways and determining NEPA requirements.”
Whyne said that no decision will be made or implemented to change from biotreatment until a minimum of six months of agent hydrolysate processing has occurred, unless the Citizens’ Advisory Commission requests otherwise.