The state-of-the-art plant is easily expandable to handle projected growth, and is the centerpiece of a long-range plan to meet future Chesapeake Bay watershed water regulations, which are likely to be stricter than current requirements.
The BRWRF is the first large-scale wastewater treatment plant to use a combination of GE ZeeWeed® membrane bioreactor (MBR), granular activated carbon (GAC) and ultraviolet (UV) technologies to meet enhanced nutrient removal rules.
Owned and operated by Loudoun Water, the plant was constructed to accommodate future growth and to reduce loading to nearby Blue Plains WWTP, which limits flow to 13.8 MGD.
Design Challenges
In selecting an appropriate water-treatment technology and process, Loudoun
Water planners and design engineers faced two major challenges:
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Achieve stringent enhanced nutrient removal (ENR) standards to improve water quality, reduce algal blooms and restore aquatic habitats in the Chesapeake Bay. |
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Implement a robust treatment process to protect drinking water quality for communities located just 10 miles downstream. |
"We have met very stringent permit requirements from the day we opened in May, 2008, a major accomplishment given the Chesapeake Bay preservation effort that drove the requirements," said Thomas Broderick, program manager for the Broad Run facility. "Phosphorous is of particular concern because it is a nutrient that promotes algae growth. Thanks in large part to membrane technology, effluent from the Broad Run Water Reclamation Facility contains just 0.1 parts per million of phosphorous, one-third the level most other wastewater treatment plants in the Chesapeake Bay watershed are allowed to discharge."
MBR Technology Is Key
A preliminary design study for the Broad Run WRF evaluated several conventional
and membrane treatment alternatives. The evaluation showed that the membrane
bioreactor (MBR) options were cost-competitive with the conventional options,
and also offered several advantages such as a reduced plant footprint, fewer
unit processes, and the provision of a pathogen barrier.
The system also allows wastewater to be reclaimed and used. “Right now we are using some of the treated effluent in the plant itself for process water and for non-potable uses such as flushing toilets,” Broderick said. “Later this year we will connect with our first commercial customer for reclaimed water, a data center that will use it for cooling. We have one other customer lined up that will use the water for irrigation, sprinkler fire suppression and toilet flushing.”
Process Overview
GE Water, a business unit of GE Energy, participated in a 2001 pilot study of
MBR technology conducted by Loudoun Water and engineering builder/contractor
CH2M HILL. The study demonstrated that the proposed treatment process would
meet the required effluent quality, and it also provided data to help optimize
the full-scale process design. A competitive bidding process followed the pilot
study, and GE Water was selected to provide ZeeWeed MBR technology.
Designed by CH2M HILL, the BRWRF incorporates coarse screening, grit removal, primary clarification, biological treatment, ZeeWeed ultrafiltration, granular activated carbon, and UV disinfection. The ZeeWeed immersed ultrafiltration membranes form the basis of the MBR system, and filter out virtually all solid particles, bacteria and other pathogens. The modular system achieves nutrient removal through the use of biological and chemical treatment processes. Biological treatment is based on a modified five-stage Bardenpho process, enabling the removal of both nitrogen and phosphorus compounds. Alum is used to maintain the effluent total phosphorus concentration below the 0.1 mg/L limit.
Engineers took advantage of the modular expandability that a ZeeWeed system
offers, building additional space into the facility’s 12 treatment trains.
The spare tankage can be filled with ZeeWeed cassettes on an as-needed basis
to increase capacity.
Phase one provides an average treatment capacity of 5.0 MGD and uses two ZeeWeed
membrane cassettes in each train. When required, phase two will add two more
cassettes per train to increase the plant’s average treatment capacity
to 10 MGD.
Award-Winning Plant
In recognition of the state-of-the art facility, the American Association of
Environmental Engineers awarded designer CH2M HILL its 2009 E3 Design Grand
Prize. The award says the plant “sets a new world-wide technology standard
for water reclamation and also provides a community amenity that will have long-lasting
educational, aesthetic, and recreational value.”
