Aquatic Agility

Tapping the Ultra-Pure Potential in Wastewater

As director of engineering John Monk notes, clean water “is critical to our ability to make microelectronics. It is used for all wet processing, working with acidic or basic chemicals, etching materials and, in some cases, depositing materials such as when plating metal.” The use of UPW makes it possible for ATL to create some of the world's most advanced microelectronics, including key technology infrastructure for projects such as the James Webb Space Telescope and the APG-81 and APG-83 radars.

But “clean” isn't enough; water must be ultra purified to remove any trace of chemical or mineral contamination. To streamline the process and ensure UPW is always available on-demand, Northrop Grumman recently replaced an on-site deionization plant capable of treating municipally supplied water and turning it into UPW. However, as production output ramped up, so did the amount of potable water used and the amount of wastewater created. To help improve efficiency and reduce total potable water usage, Facilities, Environmental Health and Safety (EHS), and UPW plant operators and engineers began looking for ways to reduce water consumption without impacting operational throughput. The solution? Resource repurposing.

Water, Water Everywhere

Water is water, right? Not quite. In the case of potable drinking water, dissolved minerals and chemicals are absorbed by humans to benefit bodily functions. In the case of microelectronics manufacturing, those same organic and inorganic materials can create critical defects or unexpected electric currents that render the products being made unreliable at best and useless at worst.

The same is also true in reverse. While Scientific American notes that the negative charge of water molecules in an ultra-pure state make them a “super cleaner” given their ability to capture even the tiniest specks of dirt or debris, UPW would be terrible as a thirst-quenching beverage since, as the SA piece puts it, “If you were to drink ultra-pure water, it would literally drink you back,” sucking out valuable chemicals from saliva. Not a great choice.

And just as consumed drinking water is converted into waste by the human body, so too is UPW as it is used in the manufacturing process and discharged to the local municipality. To help reduce total resource use, the EHS team first reached out to the deionization plant's operations team and then, in 2016, contracted Stantec to conduct water use assessments. These were “designed to identify cost-effective water conservation measures and provide rough order of magnitude cost estimates for conceptual opportunities identified by Stantec and the site personnel,” according to environmental sustainability program lead Mike Ensor.

The results were clear: The greatest potential savings came from the addition of secondary treatment process that could repurpose used UPW as supply water for the deionization plant.

Reduce, Reuse, Repurpose

“When I suggested reusing the wastewater, they jumped on the idea,” said Lou Yannone, the plant's chief engineer. But the path to repurposed UPW wasn't easy. The original deionization plant was nearing its end of life in 2018, so the team decided to double up and combine the two efforts into a single new plant. However, as Monk notes, “It was critical that they proved to everybody that the water quality was still the same before we made any changeovers — and we are measuring some things in the parts per billion category.”

After confirming that the content of the repurposed and treated resource met or exceeded the original supply water quality, the team was free to move forward with redevelopment, but according to Yannone, “It was very, very high pressure because what we were doing could potentially shut down the labs, which was the last thing we wanted to do.”