WQIF - LCSA - Broad Run Water Reclamation Facility

 

Project  Grant Amount Grant Percentage
LCSA - Broad Run Water Reclamation Facility $20,734,526 35%
 Revolving Loan Fund Project DEQ Regional Area Date Agreement Signed
No Northern Virginia Regional Office 5/30/08

Brief Project Description

Loudoun County Sanitation Authority (LCSA) owns and operates the Broad Run Water Reclamation Facility (BRWRF), which has a permitted design flow of 11.0 MGD.  The discharge is within the confines of the Dulles watershed, so advanced treatment was already dictated by the State Water Control Board’s Dulles Area Watershed Policy.  Under new nutrient discharge control regulations for the Chesapeake Bay and its tributaries, effluent limitations for total nitrogen and total phosphorus were also incorporated in the VPDES permit.

The new WRF consists of the following:  preliminary and primary treatment, secondary/biological treatment, ultra-filtration, and ultraviolet radiation for disinfection.  Solids handling processes include combined primary and waste activated solids thickening, aerobic digestion, and dewatering. 

Facilities included in the Project are described as follows:

Preliminary Treatment:  A new Preliminary Treatment Facility (not grant eligible) was constructed to provide raw wastewater influent screening, pumping, grit removal, and residuals handling.

Primary Treatment (grant eligible):  Three rectangular clarifiers are provided to enhance the biological treatment process.  In this process, solids will settle out which allowed for the biological reactors to be sized smaller.  

Secondary Treatment (partially grant eligible):  The bioreactor basins (BRB) configuration employs 5 stages for treatment: (1) Return activated sludge de-aeration/anaerobic (2) Primary Anoxic Denitrification; (3) Oxic nitrification; (4) Secondary anoxic denitrification; and (5) Membrane filtration (ultra-filtration), accompanied by reaeration.  The design incorporates flexible swing zones between most stages with a controlled dissolved oxygen level that allows simultaneous nitrification and denitrification.  The three BRB tanks – which are rectangular in shape and constructed of concrete -  are configured as three 30-foot wide passes.

The aeration system consists of six centrifugal multistage blower units that provide low pressure air to the fine bubble air diffuser system installed in Zones 5 through 10 of each reactor. Submersible mixers are used to maintain the mixed liquor suspended solids (MLSS) in suspension in anaerobic and anoxic zones.

There are three recycle streams in the biological treatment system: Nitrified Recycle (NRCY), Anoxic-Recycle (ARCY), and return activated sludge.  The NRCY and ARCY recycles will be pumped by submersible pumps installed directly in the reactors.

Effluent Filtration (partially grant eligible):  Membrane Tanks - The membranes are installed in 12 parallel concrete tanks on the east side of the BRBs and the tanks completely covered with fiberglass.  The membrane tanks are sized to process the peak hydraulic flow with two tanks out of service. Each tank has a total volume sufficient to house five 48-module membrane cassettes. Each module contains 340 ft2 of membrane fiber; therefore, one cassette could hold up to 16,320 ft2 of membrane area.

The Membrane Filtration System relies on air blowers to agitate the membrane fibers and remove accumulated solids from the fibers. The blowers discharge to a common air header that feeds all 12 membrane tanks and the blowers will improve the filterability of the MLSS The

Waste Activated Solids Thickening Improvements (partially grant eligible):  The solids retention time selected for the biological system is controlled by regularly withdrawing solids from the system as waste activated sludge (WAS). The WAS system is designed to remove solids from the surface of the BRBs. The three pumps are designed to withdraw mixed liquor or scum from either of the two WAS/scum locations.

Odor Control Facility (partially grant eligible) includes the following components: Odor Control Fan Building; Bioscrubbers, and Biofilters.

Chemical Feed Systems:  A chemical storage and feed system is provided for alkalinity addition for the nitrification process and also for controlling odor and foam.  A new methanol storage and feed system to provide supplemental carbon to the denitrification process was constructed for nitrogen reduction; chemical storage and feed for phosphorus reduction is also included in this project.

Electrical System Improvements (partially grant eligible):  Generator and Switchgear Building, along with a new standby generator, and plant wide electrical system is included.

Distributed Control System (partially grant eligible):  A new plant-wide programmable logic controller based distributed control system is provided to improve treatment plant automation and control.

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Virginia Department of
Environmental Quality
P.O. Box 1105
Richmond, VA 23218
(804) 698-4000


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