454 Water Recycling, Innovation, and Industry Wisdom with Dr. Kelle Zeiher

 Industrial cooling is one of the biggest levers industrial facilities can pull on water use—and it's getting harder to ignore as data centers and other high-heat operations grow. Returning guest Dr. Kelle Zeiher (Project Manager at Garratt Callahan) breaks down what water reuse looks like when you move past slogans and into the realities of pretreatment, concentrate management, footprint, and cost. 

Cooling water reuse: the scale of the opportunity 

Dr. Zeiher reframes "drought" beyond rainfall, emphasizing aquifer recharge and the limits of focusing only on household restrictions. She contrasts domestic use (~12%) with the much larger share tied to cooling (~50%), then connects that to why optimizing industrial cooling matters—especially when operations sit in arid, desert-like regions with limited water availability. She also shares a data-center statistic that puts "the cloud" into physical terms: ~53 gallons of purified water per gigabyte of data stored to keep environments cool enough for microchips. 

Higher cycles, RO blending, and the concentrate question 

The conversation moves into practical tower strategy: driving cycles up as far as the water and metallurgy allow. Dr. Zeiher describes a case moving from three cycles to six with RO blending and pretreatment, resulting in millions of gallons saved annually. From there, the engineering problem becomes unavoidable: higher cycles create a concentrated cooling-water stream, and RO adds its own waste stream. The key operational question is how to manage both streams without trading water savings for disposal and reliability issues. 

Minimal liquid discharge, and the AEROS approach 

"Zero liquid discharge" (ZLD) remains a theoretical target, but Dr. Zeiher is clear about the realities: ZLD can require large equipment and high energy demand. She shares a cost example where a 20 gpm ZLD concept came in at nearly $8 million in capital. Her team's approach focuses on minimal liquid discharge (MLD)—recovering roughly 80–90% of water rather than 98–99%, while reducing energy intensity and footprint. She introduces .css-j9qmi7{display:-webkit-box;display:-webkit-flex;display:-ms-flexbox;display:flex;-webkit-flex-direction:row;-ms-flex-direction:row;flex-direction:row;font-weight:700;margin-bottom:1rem;margin-top:2.8rem;width:100%;-webkit-box-pack:start;-ms-flex-pack:start;-webkit-justify-content:start;justify-content:start;padding-left:5rem;}@media only screen and (max-width: 599px){.css-j9qmi7{padding-left:0;-webkit-box-pack:center;-ms-flex-pack:center;-webkit-justify-content:center;justify-content:center;}}.css-j9qmi7 svg{fill:#27292D;}.css-j9qmi7 .eagfbvw0{-webkit-align-items:center;-webkit-box-align:center;-ms-flex-align:center;align-items:center;color:#27292D;}