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A More Resilient Campus Through Water Reuse

Reprinted with permission from Sustainable Water, www.sustainablewater.com

The WaterHub™ is an on-site water recycling system on the Emory University campus in Atlanta, Georgia which utilizes eco-engineering processes to clean wastewater for future non-potable uses. It is the first system of its kind to be installed in the United States. Emory’s WaterHub is capable of recycling up to 400,000 gallons-per-day—nearly 40% of Emory’s total campus water needs. The facility officially opened on April 17, 2015. McKim & Creed was part of the design/build/own/operate team, along with Sustainable Water and Reeves Contracting Company, that delivered the 400,000-gpd facility.

WaterHubSustainable Water, Reeves Contracting and McKim & Creed, Inc. formed a design/build/own/operate team to deliver a 400,000-gpd water reclamation facility and reclaimed water distribution system for Emory University in DeKalb County, Georgia. The system meets roughly 40 percent of the campus water needs and will reduce the university’s draw from the DeKalb County’s municipal water supply by up to 146 million gallons annually.  (Photo courtesy of Sustainable Water)

In the last decade, Atlanta has witnessed numerous water-related stresses, including: severe drought, EPA mandates to resolve critical infrastructure failures, and an extended political dispute over water rights in the so-called “Tri-State Water Wars.” As a result of these challenges, Emory University set out to explore ways to minimize its impact on community water resources and the environment. Using close to 350 million gallons annually, the University deployed conservation tactics ranging from low-flow fixtures to stormwater water reuse. As regional water stresses persisted, the campus turned to a more strategic and impactful water management solution: campus-wide water reclamation and reuse.

With an extensive district energy system supplying steam heat and chilled water to campus, the University has significant process water demands that equate to nearly 40% of campus water use. A majority (85%) of this water is used by the steam plant and five campus chiller plants. These utility plants provide an ideal opportunity for displacing a significant portion of the campus water footprint with a reliable and sustainable source of water at discounted costs.

WaterHub“The [WaterHub™] facility, housed in a greenhouse structure near Emory’s baseball fields, utilizes a unique biological treatment method involving a series of interconnected, sequentially operated, cascading reactors. Water is circulated through both aerobic and anaerobic chambers in which suspended plant roots serve as a natural habitat for a diverse set of microorganisms that form a unique ecosystem specially engineered to break down waste,” according to news release from Emory University. (Photo courtesy of Sustainable Water)

Sustainable Water designed Emory’s reclamation system to integrate into the existing campus framework using two small parcels near Chappell Park field. Up to 400,000 gallons of wastewater is mined directly out of the campus sewer system daily. Water is cleaned to Georgia reclaimed water standards through an energy efficient eco-engineered treatment process supported by solar (PV) energy production. The system has 50,000 gallons of clean water storage capacity, providing N+1 redundancy for campus district energy systems. Recycled water is distributed to the multiple utility plants and select dormitories for toilet flushing via a 4,400 linear foot “purple pipe” distribution system. At full build-out, the system will displace nearly 105 million gallons of potable water annually - providing tens-of-millions of dollars in savings to the University over the next 20 years.

The system is designed to promote research and community outreach, enhancing the concept of the campus as a “living laboratory.” With built-in lab space and easy access ports for water quality testing, the facility enables research in a variety of topics. The lower site also includes a demonstration reciprocating wetland system as a showcase to visitors interested in other sustainable treatment technologies.

WaterHub(Left) The cooling towers at Michael St. Chiller Plant now receive reclaimed water. (Right) The outdoor hydroponics and 5,000-gpd reciprocating wetland system are used by the University for demonstrative and research purposes. (Photos courtesy of Sustainable Water)

Technology Description
The WaterHub at Emory is an adaptive ecological water reclamation system designed to treat domestic sanitary sewage for beneficial reuse. Wastewater is mined from a 30-inch sewer line near the lower site and then pumped to the upper site where it enters a rotating drum screen before entering the moving-bed bioreactor (MBBR) system. The process design combines submerged fixed-film hydroponic reactors with a MBBR as an initial treatment step. After primary treatment, water passes through a small clarifier, a disk filter, and a dual-stage disinfection system consisting of ultraviolet (UV) light and an oxidizing agent (chlorine).

The hydroponic reactors utilize plants and their root systems to mimic and maximize natural treatment efficiencies associated with oxygen diffusion and habitat creation. Below the root zone is an artificial media, called BioWeb, that extends the submerged fixed-film surface area for higher levels of microbial incubation. The system is designed to provide a high hydraulic throughput with a small physical footprint and low energy demands. Along with outdoor hydroponic reactors, the lower site also boasts a small 5,000-GPD reciprocating wetland system, which is used by the University for demonstrative and research purposes.

WaterHub

The WaterHub project at Emory University recycles 400,000 gallons of water per day for use in boilers, cooling towers and toilet flushing. "With this facility, we're taking a major step forward by reclaiming our own wastewater, which will save tens-of-millions of gallons of potable water every year," said Matthew Early, vice president of campus services at Emory. (Photo courtesy of Sustainable Water)

WaterHub

(Drawing courtesy of Sustainable Water)