Campus Recycles Wastewater

WATER CONSERVATION AT THE EMORY UNIVERSITY CAMPUS IN ATLANTA, GA HAS BEEN SIGNIFICANTLY BOLSTERED WITH A WATERHUB SYSTEM.

 

Since 2015, the campus utilizes WaterHub, a water reclamation and reuse system that reduces Emory’s demand for potable water. Water use was 350 million gallons annually, which included operating five chiller plants and one steam plant.

Matthew Early, vice president for campus services at Emory University, shares the story behind the project.

By Facility Executive Staff
From the April 2018 Issue

What was the motivating factor and goals for this project?

In 2011, when we discovered WaterHub, Emory already had many water conservation efforts in place—low flow fixtures, urinals, and showerheads; rainwater collection; and capturing graywater for reuse in toilet flushing. But, these efforts seemed finite, and by that I mean: What was the next innovation to push conservation further?

How did you discover the WaterHub approach?

One of my engineers and one of my project managers were at a conference and they came across a company exhibiting there, Sustainable Water [a water management services provider based in Glen Allen, VA]. The company was showing its WaterHub system technology, which at its core is manmade wetlands; the system uses plants to clean wastewater. My engineer, project manager, and their leadership at Emory presented the idea to me, and then we met with Sustainable Water. After their presentation, I wanted to move forward.

What did your decision-making process entail?

We agreed that I would fund a feasibility study, and if we moved forward that would go into the cost of execution. The study examined our systems, such as how much domestic water do we use across the enterprise? And what are the uses? At Emory, our buildings are metered for water, but we didn’t have a breakdown on water by use (e.g., toilets, sinks, the heating and cooling systems).

Our team, working with a third party, found the percentage across the board of what the various domestic water uses were on campus. They presented this to me, and a significant finding was that 40% of our domestic water use (350 million gallons annually) was being used on the mechanical side (chiller plant and steam plant usage). This 40% equaled 400,000 gallons per day.

I thought that 40% for the chiller and steam plants was a huge number (in terms of potable water being used for those applications; this is not above the national norm), and that put our research into WaterHub into the second phase. Now, the question became: Can this technology supply enough water to the chiller and steam plant facilities to eliminate the need for domestic water there?

Since the WaterHub would draw from the campus sewer system for the water it reclaims, we needed to find out if that source was feasible. We’d be building the system on our campus, and we needed to know if it could be sited efficiently. You put the facility near the source so you’re not pumping sewage a great distance.

We found on of our major sewer trunk lines runs on the shop side of our campus, so the systems could be built on the industrial side of the campus, which worked out really well. They tested the water flow in the trunk line to ensure it could provide the 400,000 gallons per day we needed, and it did.

Next, we visited several sites in France that were using similar technology. These were not WaterHub projects, but similar. (At the time, our WaterHub was the first of its kind in the United States.) One of my main concerns was that the system would not smell like sewage. It did not. Their systems, like ours, look like greenhouses and the plants within act like wetlands in nature do by cleaning the water. The cleaning processes occur under the plants in the reactors (the concrete tanks that house the plants) After that visit, we decided to move forward.

How does the system integrate into the campus?

The system is a 4,400 linear foot distribution system, and it is divided into two locations: an upper site and lower site. The upper site is a 3,200 square foot greenhouse, and this is the main area of the system. Nearby, the lower site includes outdoor plantings. This was done on two sites, because the upper site could not accommodate the full system that we needed.

What have the results been? What are the lessons learned?

The WaterHub began operating in the spring of 2015, and we hit the goal of 400,000 gallons of reclaimed water per day within the first year.

We also learned important things as the system continued operation. For one, as demand for the chiller plants and the steam plant changed throughout the year… there’s a high need for chilled water in summer and low steam demand in summer, for instance. There were times when we only needed 100,000 gallons of water per day for those facilities. We needed to tweak the WaterHub operations, in terms of how much water it processed. We throttled the water to meet the demand, but this impacted how the plants were processing the water and the resulting water chemistry (which impacted the steam plant maintenance).

Ultimately, we decided not to throttle, and that we would produce a consistent volume of water. Any excess from the 400,000 gallons, not used by the chiller and steam plants, are now used elsewhere. That is why we added other uses, such as the residential hall toilets. And we are considering irrigation uses now.

Another lesson learned was related to the sewer line. Initially in feasibility and through time, the operators took samples of what was in the sewer system (e.g., various objects). But once the plant was up and running, the impellers on the pumps would jam up as they tried to grind objects. They upsized the impellers to solve that issue.

What is operations and maintenance like for you and your team?

 

 

 

 

 

 

 

 

 

As part of the Water Purchase Agreement we have, Sustainable Water maintains and operates the system. They have one person doing that. My engineers on the utility side keep me up to date, which includes reports on the system.

As part of the agreement, we pay for only the water we use and we’re not held liable for the 400,000 gallons per day. We’re always looking to reduce energy load, so as we reduce heating load and cooling load, that reduces the needs for the chiller and steam plants to be operating, which will reduce water use. However, we want to use that water and we want to be good partners, so we look for ways to use excess water. For example, using the water for toilets in several residential halls was a follow on to the initial planning. And we are looking at irrigation possibilities.

Can you share any additional comments?

Our water costs aren’t very high, so other organizations might get better return on investment, based on their water costs. Still, I worked with our municipality to try to obtain sewer credits, since we would be using less domestic water from that system. We were able to get sewer credits.

That was part of the feasibility conversations we were having with the municipality and other groups, beginning in 2012 to 2015. We met with the county, Georgia EPA, and the federal EPA. My recommendation to anyone interested in this technology for their facilities is to talk with the municipality, the county, etc. to make sure the system would be approved. There are a lot of interesting conversations to have around this type of system.

Also, the system uses very little electricity. And we worked with Georgia Power and asked for a partnership. They donated solar panels, which provides power to the pumps.

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