In Fulton County, Georgia, USA, the community, commerce and the environment are set to reap the benefits of a multi-million dollar investment in the expansion of its Big Creek Water Reclamation Facility. Originally constructed 51 years ago with a capacity of 0.75mgd, by 2015 the facility had reached 80% of its average daily flow capacity. By law, plans had to be formulated to upgrade and increase its capacity. The result has been Fulton County Public Works Department investing $300 million on a progressive design-build upgrade of Big Creek to meet current and future drinking water and wastewater treatment demands. Construction commenced in 2018 and the plant will come on stream in 2024.

The project replaces aging equipment, removes older and unused facilities at Big Creek, and incorporates additional enhancements to improve operational reliability. Central to this performance is the introduction of advanced Membrane Biological Reactor (MBR) technology which will produce significantly cleaner water and contribute to increasing flow capacity from 24mgd to 38mgd. While the flow capacity is raised, the discharges to the nearby Chattahoochee River in Big Creek Basin will be reduced by up to 50% from existing permit limits.

Commenting on the project, Roy Barnes, P.E., Deputy Director of Public Works, Water Reclamation says: “The discharge levels are very strict so we standardize our operation on certain parameters. Monitoring is undertaken daily and we also have to submit monthly reports to the regulatory authorities. Certainly, the water that we put back into the river is much cleaner than when we take it out.”

The massive investment in the treatment plant demonstrates Fulton County’s commitment to providing its one million-plus citizens in the north of the county with the highest quality services, protecting the environment and enabling growth and further economic development.

Pump Requirements

A significant aspect of the new treatment plant is that it operates by gravity. Because the wastewater entering the plant is received from external pump stations, and taking into account the influence of the significant elevation change across the site, the design for the new facility reduces the need for pumping in several parts of the plant. This even includes the flow through the membranes of the biological reactor. As a result, significant long-term operational savings have been identified as fewer pumps reduce power consumption costs.

However, pumps are required for certain special process applications. Where power is a major consideration is the demand for operating the Return Activated Sludge (RAS) pumps and the blowers used for process aeration and membrane cleaning. This equipment requires large pumps with motors up to 250hp.

This aspect of the project has involved Georgia and Alabama-based Pump & Process Equipment Inc. (P&PE), an authorized representative of KSB. P&PE has had a close working relationship with Fulton County over many years, supplying the Big Creek plant with several pump types, primarily wastewater process pumps manufactured by KSB.

Thus, when the expansion project was first discussed in 2018, P&PE was well-positioned to present the capabilities of KSB pumps for various process fluid handling applications around the new plant. The introduction of the MBR plant using Kubota technology also provided the opportunity to highlight the proven capabilities of KSB’s KRT dry pit submersible pump series for handling RAS. Working in concert with Kubota Engineers and KSB, proposals and design data was provided to Fulton County and Brown & Caldwell (the project engineer), who included KSB’s offering for RAS and CIP pumping requirements.
Fulton County had specific requirements for the new project, as Roy Barnes explains: “We specified dry pit submersible pumps with internal self-cooling because we did not want to use wastewater for cooling. These capabilities, combined with high output requirements could be met by the KSB KRT pump range.”

KSB KRT Pumps

Bill Uhrig, Vice President at P&PE takes up the narrative. “The KSB KRT pump has been designed specifically for wastewater treatment applications where solids-laden fluids are encountered and clogging is a challenge,” explains Bill. “Suitable for both dry and wet pit installations, this robust pump series provides a variety of material offerings, several types of impellers and premium efficiency motors. These cutting-edge technologies were detailed in the project tender specifications drawn up by the plant’s design engineers, Brown & Caldwell.”

KSB KRT pumps are true workhorses for the wastewater treatment and water supply sectors, operating in many applications around the world where the most challenging water industry applications have to be satisfied. As dedicated wastewater pumps, the KRT range is more than capable of handling the type of solids-laden fluids present in wastewater treatment plants.

P&PE has treated the selection of pumps for the MBR’s RAS pumps as a separate project, largely due to the complex design and operating requirements of the station. “Our response to the brief was to supply eight vertically mounted KRT 235HP dry pit submersible pumps for recycling biologically active sludge from the membrane basins back into the treatment process at the Biological Nutrient Removal (BNR) basins. The pumps are located in the membrane gallery and share the space with all of the large aeration and agitation blowers.”

RAS Pump Installation

Nick Abbatiello, KSB’s Southeast Water Market Regional Manager reports that the RAS pumps are the largest pumps at Big Creek. “Utilizing duplex stainless steel, three-vane non-clog impellers, each pump has a 20-inch discharge and a 30-inch suction line feeding them. The rated duty point is 17,385 GPM @ 31.3ft TDH and will run at different speeds to accommodate the initial flows, but are sized for the ultimate buildout of the facility,” says Abbatiello. “The difficult part of this application was accommodating the very high flow when there was only 32ft of head. This means that each of the pumps is brought on stream in sequence as the flow increases to handle the demands of the plant.

Two KSB Sewatec 50HP end suction centrifugal pumps were also installed in the MBR gallery for CIP chemical cleaning of the membranes. These are rated for 1,500gpm @33ft TDH. When it becomes necessary to clean the membranes, these pumps are activated and recirculate the cleaning solution for future reuse.

Process Duty Pumps

Running alongside this part of the contract, P&PE was also involved in providing contractor Archer Western with a range of KSB KRT pumps for specific process duties. P&PE is providing three different types of impellers for these varying applications, along with three different types of motors to meet all specific requirements. The design of the K-type, E-type and D-type impellers and the pump housing ensure a free flow of solids-laden liquids; combined with high-efficiency motors, the KRT delivers significant operating cost savings.

In the majority of applications the pumps incorporate K-type impellers and come in various sizes and flow capabilities for handling different processes throughout the rest of the treatment works. These include pumps for digester basin recirculation pumping, servicing the de-watering, filtrate and building drainage system, servicing the equalizing basin return water, anaerobic feeding, fine screening, RAS anaerobic screening, and RAS rescreening. Three of the six areas of use are being equipped with closed-looped, internally recirculated glycol for a dry type installation. These are similar to the RAS pumps, but on a much smaller scale.

E impellers (single vane non-clog design) are being used for the fine screening pumping application. These impellers are providing high pumping efficiencies, low HP requirements and premium efficient motors. Elsewhere, D impellers (open, diagonal single vane design) are being used for the digester basin pumping requirements. The D impellers are an ideal solution for pumping fluids with higher solids contents. These pumps are also being provided with special high-temperature rated motors, good for liquids up to 140⁰ F.

Summary

“By the middle of 2023 we had supplied roughly 45 KSB pumps,” says Jimmy Mulvaney, President of Pump & Process Equipment in Georgia and Alabama. “Throughout the year-long intensive process of design considerations for the RAS pumps in particular, and through collaboration with the Design Build Team consisting of the Engineer (Brown & Caldwell), the contractor (Archer Western), Fulton County Engineers, KSB, and P&PE, we were able to successfully meet the difficult hydraulic conditions to the satisfaction of all the involved parties.”

“We have been impressed by the relationship between all the parties involved in the project, which has been well managed by the contractor,” comments Roy Barnes. “I am grateful for the effort that KSB exerted particularly during COVID, as this gave us concerns about delivery dates being met. Because of access to parts of the plant, it was essential that the pumps had to be installed while the building work was going on. They worked it out and the pumps arrived right on time.”

Serving one of the fastest growing regions around the Atlanta, Georgia area, the Big Creek Water Reclamation Facility upgrade and expansion, with a service area of 70 square miles, is the single largest project in Fulton County’s history. Through years of planning, collaboration, and a culmination of vision, engineering, and equipment, Fulton County businesses and residents will soon be the beneficiaries of this sweeping design-build project providing plentiful and clean water and waterways for years to come.

About the Author:
Bryan Orchard is a UK-based independent journalist. He has been reporting on the global pump industry and process technologies for over three decades.