Operators at the Southampton Regional Water Reclamation Facility had a lot to learn when their brand new five-stage Bardenpho plant started up in 2010. Now, having mastered the new processes, they’re in the driver’s seat. That’s because any expansion of the plant, which has a modular plug-and-play design, will simply involve more of the same.

A thorough training program has been the key. The transition was difficult, recalls Raymond Bryant, chief systems operator at the 1.25 mgd (design) plant, in the Town of Courtland in Southampton County, Va. The county’s old plant was a 0.3 mgd oxidation ditch with sludge drying beds. “We’d never seen this new process before, myself included,” Bryant says. “But we have a good bunch of guys who are dedicated to wastewater treatment.”

Adds Ron Eisele of the Timmons Group, Richmond-based designers of the plant, “That was their biggest challenge — training the operators to run these new processes. It was quite an undertaking for these guys, just the size of it, getting your mind around a 50-foot clarifier when you’ve been used to 20 feet, or going from a small aeration process to the Bardenpho, which is the first five-stage system of its kind in the state.”

Vendors and the Virginia Rural Water Association provided most of the training, which took about two months. Bryant says the trainers provided good leave-behinds, including useful videos: “I still find myself pulling out a video to see if I’ve missed anything.” Mid-Eastern Builders, the contractor, was helpful during startup. “Sometimes when you have problems it’s just nice to have somebody pick up the phone at the other end,” Bryant says.

Old to new

For years, the previous plant treated flow from a small number of customers and several industries in the eastern part of this rural southern Virginia county. But the facility was prone to overflows from severe infiltration and inflow to the sewers or from high water in the Nottoway River, the plant’s receiving stream.

“The plant was antiquated, and things were breaking down all the time,” says Bryant. “We were feeding gaseous chlorine, and we have a trailer park within 1,500 feet of our property.” With industrial expansion on the horizon, the county hired the Timmons Group to design the improvements, and the firm used an efficient design-build process to construct an entirely new plant alongside the old one in about 18 months.

“We broke ground just 40 days after signing off on the paperwork,” says Eisele. “Design-build is a very efficient approach. Designer, contractor, and owner work hand-in-hand.” The new plant was built within the footprint of the old one and was elevated to meet floodplain regulations.

Driven by influent pumps (Gorman-Rupp Co.), raw wastewater enters through a headworks with a stair-step screen (Vulcan Industries) and a screenings compaction and washing unit (Ovivo). Grit is removed and dewatered in a vortex system (Hydro International).

The five-stage Bardenpho process (Ovivo) provides biological treatment using a series of anaerobic, anoxic, and aerobic zones equipped with submerged mixers. Bryant and his staff carefully control dissolved oxygen to achieve the desired results.

Treated water settles in a pair of 50-foot-diameter clarifiers (Ovivo), and then passes through a cloth disc filter (Aqua-Aerobic Systems). Three banks of UV light units (Ozonia) disinfect the effluent before post-aeration on the way to discharge. Pumps (Gorman-Rupp) are on hand to move water away from the plant to the river in case of storms or floods.

Solids are digested aerobically, thickened, and dewatered in a centrifuge (Alfa Laval). Dewatered cake is taken to a nearby composting site. All plant processes are automated and monitored via a new SCADA system (Systems East).

At startup, the state required the county to staff the new facility 16 hours a day because of the high performance standards. However, once the staff showed competence and met effluent permit limits regularly, that requirement was lifted, and the plant is now staffed on a typical 8-hour shift. “We’ve never had a violation since startup,” Bryant says.

Like a Lego set

The county kept the future in mind in planning the new facility, and the Timmons firm took a modular approach to the design. “We essentially built in future expansion using today’s money,” says designer Eisele. “It’s pretty forward-looking.”

The current design of 1.25 mgd can easily be expanded to 2.5 and 3.75 mgd, just by adding more units to the processes. “We knew that we didn’t need 3.75 right now, but everything is in place to allow us to expand quickly in the future,” Eisele says.

Actually, the headworks is already set up for 3.0 mgd, but with the rest of the plant, it’s just a matter of adding equipment and opening valves. The design also means the staff will be ready for any expansion because the equipment will simply mirror what’s already there.  

Learning the ropes

Besides Bryant, the plant team includes Dennis Beale and Bruce Whichard, lead operators; Keith Jackson and Tim Christianson, operators; and Milton Billups, trainee and pump technician. Charles Hyman, Daniel Fowler, and David Joyner staff another Southampton County plant but are trained on the treatment processes and are available to help out if necessary.

Once trained, Bryant and the staff had to move to the hands-on stage and make things work. The new biological system and SCADA setup proved challenging. “The hardest thing was trying to figure out the proper balance in the biological system, since we had a small load of only about 100 mg/L of BOD coming in,” says Bryant. “The food to the system was real limited.”

The team had to get the proper dissolved oxygen (DO) and mixed liquor in each of the tanks or zones. “In the Bardenpho process, influent enters the anaerobic zone first, requiring a low DO, then the anoxic zone requiring zero DO,” says Bryant. Another anaerobic zone follows, and there the mixers bring DO back to about 0.5 mg/L. Next is a second anoxic zone, and finally the reaeration zone, where DO needs to be at least 2.0.

Bryant sees a lesson from his team’s experience for those starting up new biological treatment trains: If you previously had a biological process and it was working fine, apply some of the same numbers to the new system. “Basically, after we got started, we used the same mixed liquor levels we used in the old plant and achieved the same settling ability in the clarifiers,” he says.

The SCADA system required another learning curve. “Most of us didn’t grow up with a computer,” says Bryant. He admits it was difficult until staff understood the workings of the system — it took about six months to work out all the bugs. “It’s simple now, and useful,” says Bryant. “We can control just about everything from the control room in the lab area.”

While most everything worked as planned, the staff made some changes with the aerobic digesters. The three digesters (one small, two larger in size) have a combined capacity designed to serve the plant at its maximum flow (3.75 mgd). As existing flows are relatively low, the treatment plant staff started off just using the smallest one. Soon, however, the material from the pumping stations and scum pumps forced a switch to one of the larger digesters.

“That way we could hold the sludge a little longer,” Bryant says. “We were pushing it through the small digester too quickly.” The change improved the thickening and dewatering properties of the final biosolids product, which averages about 20 percent solids out of the centrifuge.

Looking ahead

With startup and training in the rearview mirror, a Virginia Rural Water Association System of the Year plaque on the wall, and a perfect record of compliance from day one, the staff is well prepared for the future. The plant has no phosphorus or nitrogen requirements yet, but Bryant expects to see those limits down the road. In fact, the plant is designed to meet an expected nitrogen limit of 10 mg/L.

In addition, future industrial expansion will add to the amount of wastewater needing treatment. “A new wood pellet mill will come online fairly soon,” explains Bryant, “and it will use a lot of water and produce a lot of wastewater.” With the new processes and expandable features of the Southampton Regional Water Reclamation Facility, Bryant and his staff are in a good position to deal with these new challenges.

Meantime, says Bryant, it’s just nice to have a new plant: “With the old plant, something was always broken or not running. Nowadays, we don’t have to worry about that.”