July 2012, Vol. 24, No.7

Plant Profile

Coppermine Water Reclamation Facility

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Location: Hiram, Ga.

Startup date: July 2009

Service population: 6000 

Average daily flow: 2271 m3/d (0.6 mgd)

Peak flow: 7570 m3/d (2 mgd)

Annual operating costs:

Membrane system — $252,000

Aerated lagoon/land application system — $90,000

The Coppermine Water Reclamation Facility in Hiram, Ga., which was built in 2008 and commissioned in July 2009, is unique for several reasons. First, a 3785-m3/d (1-mgd) membrane bioreactor (MBR) sits adjacent to an older, 3910-m3/d (1.033-mgd) aerated lagoon system with a clarification step on the back end. While the older system land-applies its effluent, the MBR four-stage process meets strict permit limits, including a total phosphorus limit of 0.13 mg/L to enable effluent discharge into the Chattahoochee River Basin (see table, below). Two Class 1 operators run both the aerated lagoon/land-application system and the MBR system.

Second, the Coppermine facility is one of four MBR plants that operate as part of a decentralized water reuse system in Paulding County. Two of these plants supply three golf courses with irrigation water. One of the plants supplies water for residential irrigation. The Coppermine facility currently has no end users for reuse water but will supply water to a new hospital for cooling-tower makeup and landscape irrigation.

Phase 1 of the Coppermine MBR system includes 22 membrane cassettes, each containing 400 membrane cartridges. The total membrane area is 7031 m2 (75,680 ft2), and the MBR operates at a mixed liquor suspended solids concentration of about 14,500 mg/L. When dictated by flow, an additional 22 membrane cassettes can be added to the system (Phase 2) to double its capacity to 7570 m3/d (2 mgd). The tanks for this expansion were constructed during Phase 1 and are ready to be put into service when needed.

 

Absent permeate pumps 

Perhaps the most unique thing about the Coppermine MBR system is that it does not use permeate pumps. Instead, the system uses gravity to push flow through the membranes.

Gravity systems are the simplest systems from a control and component standpoint. They eliminate the need for permeate pumps, lower total system cost, shrink the installation footprint, and simplify the control system. The driving force required to move permeate across the membranes and through the permeate piping system is generated solely by the head of water — between 1.2 and 1.8 m (4 and 6 ft) — above the membrane units. 

The permeate from the gravity MBR system at the Coppermine facility is disinfected using two banks (one duty, one standby) of ultraviolet lamps and discharged into an unnamed tributary of Mill Creek, which in turn flows into the Chattahoochee River Basin. Solids from the MBR process are dewatered using a centrifuge and sent to a local landfill.

 

Shared headworks 

The gravity MBR system shares its headworks treatment with the aerated lagoon system. Two 3-mm band screens remove debris from the influent and are followed by grit removal. Then, the flow is split between the site’s two treatment systems; 3785 m3/d (1 mgd) goes to the MBR, and the rest goes to the land-application system.

The shared headworks led to a challenging situation at the facility. For 9 months, debris bypassed the fine screens and accumulated in the MBR system, due in part to a 102-mm (4-in.) gap around the screen. The result was some minor membrane damage and localized dewatering (i.e., sludging or caking). 

In response, Ovivo USA (Salt Lake City), the MBR system supplier, sent an emergency team to assist the facility’s operators in assessing the damage and helping with cleanup. To manually clean the system’s 8800 cartridges would be a labor-intensive and time-consuming process, taking 4 to 6 weeks. Instead, the company deployed its automated Rapid Recovery Unit to reduce cleaning time significantly. Using this equipment, the membranes were completely recovered and the system returned to 100% permeability in a fraction of the time.

Of the 8800 membrane cartridges that were exposed to the debris, only 220, or 2.5%, were damaged and had to be replaced.

 

 

Information compiled by Maria Hamlin, product engineer for MBR systems in the Austin, Texas, office of Ovivo USA (Salt Lake City), and Russell Kelly, wastewater division manager at the Paulding County Water and Sewer System (Dallas, Ga.).

 

Coppermine Water Reclamation Facility effluent limits 

Parameter 

Permit limit 

Average performance 

Carbonaceous biochemical oxygen demand

2.7 mg/L

1.78 mg/L

Total suspended solids

5 mg/L

2.0 mg/L

Ammonia–nitrogen

0.5 mg/L

0.3 mg/L

Total phosphorus

0.13 mg/L

0.08 mg/L

Turbidity

3 NTU

0.05 NTU

NTU = nephelometric turbidity units.

 

©2012 Water Environment Federation. All rights reserved.