End-user Insight: Water strategy at Intel's Ocotillo site

Kelly Osborne is a staff engineer and Site Water Champion at Intel Corporation. Her focus is water conservation through optimizing water use, wastewater treatment, and reclaim. She spoke with Ultrafacility about Intel’s water strategy at the Ocotillo site and globally.

The group provides a collaborative forum for facilities experts to align on best practices, benchmark performance, and communicate the unique needs of semiconductor facilities to the community.

How would you describe the incoming water quality at the Ocotillo site and how does this influence your water management decisions?
We have fairly hard water at our Ocotillo site. The City of Chandler supplies our water, drawn from the Colorado, Verde, and Salt rivers, and some groundwater. The Salt River, true to its name, contributes higher hardness than we see elsewhere, so we face challenges that most other Intel sites don't have to worry about.

For example, unlike in a typical UPW system, here in Arizona, the first pass reverse osmosis (RO) reject can't be sent directly to the publicly owned treatment works (POTW) or for immediate reuse because that cycles up the waters hardness. Chandler is unique in that it's a zero-discharge city; all treated wastewater gets reused for reclaim purposes, including for irrigation within the communities in Chandler and in the Gila River Indian Community. High total dissolved solids (TDS) water can’t be used for irrigation, so we generated a public private partnership facility called the Ocotillo Brine Reduction Facility (OBRF). The facility uses cold lime softening, followed by Ion Exchange (IX) and RO processes to treat the first pass RO reject, helping the city meet lower TDS levels in their POTW effluent and allowing us to reuse that water on site.

What technologies are currently used for water reuse at the site and where in the fab is reused water applied most effectively?

We have several layers of reuse at the site. We've worked with tool vendors to push direct reuse on the tool. We also have systems that capture water from tool maintenance purges or cleaner wafer rinses. That water is reused within facilities equipment without any treatment. Then the OBRF allows us to reuse the first pass RO reject water which goes back to our UPW makeup tanks.

The site is also able to send most of its industrial wastewater to our onsite treatment facility. Here we have the bio nutrient removal, the membrane bioreactors for ultrafiltration, and then that permeate is treated by ion exchange and reverse osmosis. The brine from that RO process goes to thermal treatment, so it's a near Zero Liquid Discharge (ZLD) process. The thermal process includes a brine concentrator, crystallizer and centrifuge to produce a salt and recover as much water as possible. That recovered water is sent for facilities use onsite including cooling towers, abatement units and scrubbers.

Is Intel exploring ways to move towards recycling for UPW makeup? Do you think that would be something that would see in the future?
It’s definitely a goal and I think we are closer than before. We are working on using our onsite water permeate for UPW makeup, but we must understand which constituents can cycle up. The more you reuse water internally, the more low molecular weight compounds can build up. We've got to prove to the factory that new makeup source will not create defect issues which could impact their yield. We are exploring how to pilot recycling in one of our sites, looking at opportunities to segregate tools that are fed with recycled water to see how that would perform. So, it's under investigation and qualification.

How have digital tools and sustainability modelling influenced your water strategy, at the Ocotillo site and more globally?

Our overall corporate sustainability goal is to be net positive for water use by 2030. Since some water is lost to evaporation, we do replenishment projects to restore that water. We look at the Aqueduct tool, the WEF water modelling tool for what areas of water stress there are within our basins, then work with NGOs to figure out the best projects within those basins.

Within our development factories, we model what the waste profiles, its constituents and the water usage will be for any new technologies. Having those projections, enable us to analyse current system capacity, determine if a new waste needs treatment whether existing systems can handle it or if expansion is needed. This ensures that we can treat specialty waste and recover as much for upcycling as possible.

We also have a water modelling application or digital twin that reflects the various systems on site. The modelling shows how potable water comes in, how it gets treated to UPW levels, facilities equipment water use, the wastewater generated, how it's reclaimed, and then how we can optimize the use of that reclaim. We can prioritise how that reclaim water is used to optimize freshwater withdrawal as well as remaining compliant with any regulations.

What advantages and disadvantages do you see in onsite water treatment compared to working with external partners such as municipalities?
The advantage of having an onsite water plant is direct control and ability to influence is operational output. You know exactly what's going into it, have control over operations and treatment capabilities and can optimize operations to maximize the reclaimed water production for your needs. Limiting the unknowns is especially important as you're moving towards feeding UPW with that reclaim.
The downside is obviously the cost and full responsibility falling on your company. When you use external reclaim sources, you partner with the municipality or other companies in a technology park, so you're sharing that capital intensive and operation expense budget. But you don't have as much control over what's going into the plant, or the operations.

With the OBRF, although Intel finances it and is the only source and only customer, it’s owned and operated by the city. Sometimes the two parties can have different operational views. But it's also a very good opportunity to work through those two different lenses and understand the best path forward, using the municipalities’ decades of experience.

Our private on-site water treatment plant, the OBRF, and the POTW wastewater facility all in close proximity. We're able to tap into the knowledge base of our municipality. When we see something like biological issues at our onsite plant, we can go to them as experts to understand how to react. I think it makes us stronger, and it gives the municipality an insight into what their industrial partners are doing.

Just Oregon and Arizona have on site reclamation plants. What influences the decision to invest in on-site reclaim?
Cost is obviously a big consideration. You also certainly want to look at whether there are opportunities or plans to expand one day. One of the benefits with the onsite water treatment plant at the Ocotillo site is that we were able to build 2 new factories on site without having to renegotiate permit limits with the municipality. We’re able to treat our wastewater to maintain the current limits.

However, the infrastructure required for these on-site treatment plants is massive and costly, so there are barriers to fast flexibility. For example, our end-of-pipe solution is pretty power intensive. When we were developing the site years ago, that was not as big a consideration. Now, there are lower energy cost solutions available, and the water energy nexus is becoming more important. How do we get this water use with less energy, would you rip out what you have and put something new in? Probably not, but as you're proliferating across sites, or if you start to get to end of life equipment, making changes to reduce energy consumption is definitely a consideration.

One of the things that we do to offset that is looking at renewable energy sources. We work with our providers to diversify their energy portfolios to make sure that we're, doing that in a sustainable, responsible manner. At the Arizona site, we are on 100% renewable electricity.