George Calloway and Joe Derbyshire came from different backgrounds: Calloway from a machine shop business he owned and operated, and Derbyshire from a lifetime in water and wastewater treatment.

Yet they combined their strengths, ingenuity and hard work to operate the City of Fruitland (Md.) Wastewater Treatment Plant, built as a biological nutrient removal (BNR) facility, as an enhanced nutrient removal (ENR) operation.

“Because our effluent ultimately reaches Chesapeake Bay, our nutrient removal specs are fairly stringent, with a monthly average phosphorus of 2.0 mg/l and total nitrogen of 10.0 mg/l,” says Derbyshire, director of utilities for the City of Fruitland. “We are consistently achieving total nitrogen levels of less than 3.0 mg/l, which is considered to be enhanced nutrient removal.”

That would not be impressive if the plant were designed as an ENR facility. The facility, where Calloway is plant superintendent, was upgraded in 2002 from a 0.5 mgd trickling filter plant to a 0.8 mgd (design) BNR plant to meet a growing population and a more stringent discharge permit. The facility includes:

• Andritz Hydrasieve fine-slot screens
• Eutek (Hydro International) grit removal system
• Two Jet Tech (Siemens) 800,000-gallon concrete sequencing batch reactor (SBR) tanks
• Jet Tech post equalization tank
• Davco (Siemens) traveling bridge sand filters
• TrojanUV disinfection system

The plant is controlled by an Allen-Bradley (Rockwell Automation) programmable logic controller and a Jet Tech/Integrated Controls SCADA system with the Wonderware program (Invensys Operations Management). The control system is key to the enhanced nutrient removal.

“Our ultimate goal was to achieve 8 mg/l nitrogen removal and 2 mg/l phosphorus removal,” says Derby-shire. “But our permit specified that we would operate the plant to achieve the lowest levels we could. We were able to do this with George’s expertise in control systems and his modifications to our SCADA system.”

Controls expertise

Calloway was hired as plant superintendent in 2002, halfway through the new plant’s construction. Although his background was in machine operations, he had known Derbyshire for years and was looking to change professions. After the upgraded Fruitland plant started up in 2003, Calloway operated the SBR system for a few months to understand where he could make changes to optimize the process. He looked at the SCADA system and saw the need for some additional controls.

“We wanted to have more control over the aeration process monitoring, but the SCADA provider was a little leery of having us do that, because they were afraid we would mess it up,” he says. “They did end up allowing us to make changes so that we could monitor the anoxic times and the mixed liquor, and that gives us a lot more control over our process. We added blower controls on the screen, additional controls for some valve operations, and timing.”

Calloway also added remote access for operators to check plant status at any time so they could make process adjustments when needed. His background owning a machinery fabrication/installation business in the sawmill and poultry processing industries was invaluable, as was his work in managing and operating a soft-shell crab production plant. At that facility, he monitored and maintained dissolved oxygen and pH, and maintained all test results and discharge monitoring results required by the state.

“The mechanical processes at the Fruitland plant were the easiest for me because of my previous experience with pumps, blowers and piping,” he says. “I learned the biological part from in-house training with Joe and took classes from the Maryland Rural Water Association (MRWA), the Wastewater Operators Association (WWOA), and the Maryland Center for Environmental Training (MCET) during my first three years.”

Peter Bozick, project director with the George, Miles & Buhr (GMB) consulting firm, says, “By integrating the DO control and being able to turn the air system on and off, George maximized the ability to denitrify. In my opinion, it’s the automated DO control that set this plant apart.”

Biological expertise

The plant’s third-year annual average results were outstanding: 2.3 mg/l total nitrogen and 1.2 mg/l total phosphorus, obtained biologically with no chemical addition. But that took time to achieve.

“We experimented with the SRT (solids retention time) for the SBRs and found that we had a narrow range to work within,” Derbyshire says. “We were never far off, but we ran it both at the low and high ends of the scale before getting it in the middle.”

The plant has also met or beaten its permit limits for BOD, TSS, pH, DO and fecal coliform. The success is a team effort. Says Bozick, “Joe had a hand in choosing the equipment, and used his expertise on the biological side of the wastewater treatment process. George’s talent is on the controls side. They worked together closely to monitor the process and tweak the controls to get the best results.”

Derbyshire started his career as superintendent at the Fruitland plant in 1973. In 1978, he was promoted to director of utilities for the water and wastewater facilities. From 1975 to 1985, he was lead instructor for water and wastewater courses at Wor-Wic Community College in Salisbury.

Derbyshire started learning about the biological wastewater process in 2003, after the upgraded Fruitland plant came online. Although he has a bachelor’s degree in biology and did post-graduate work in environmental science, he learned about wastewater treatment from a book. “I spent many months reading Biological Wastewater Treatment, second edition, by Grady, Daigger and Lim,” he says. “It discusses the chemistry and biology of nutrient removal.”

Relying on teamwork

Calloway and Derbyshire have some great company in chief operator Dominic Dilegge and operator/lab technician Mike Wilson. Derbyshire, Calloway and Dilegge are Class 5A certified in operations, and Wilson is a certified lab technician working on his 5A operator certification.

“Dominic and Mike were on board during the construction,” says Derbyshire. “Dominic worked for the contractor who built the new system and came to work for us when the project was completed. They got hands-on, in-house training with the new equipment through the MRWA and MCET.”

Regular nutrient testing in the laboratory is key to the plant’s success. “You have to do process control testing daily; you’d be lost without it,” says Derbyshire. They sample for nutrients twice a week for reporting purposes, and their lab technician samples throughout the day to get batches at different times in certain portions of the cycle. For compliance, the plant prefers to have third-party verification on the testing, which is why they also send samples to an outside lab for nitrogen and phosphorus analysis.

The plant staff does most of its own maintenance and grounds work. Four years ago, they started using pre-release inmates from the state prison to do grounds work, painting and general maintenance, freeing up the staff to do other jobs. That enabled the plant to continue operating with current staffing.

“We have gotten the results we have because of teamwork,” says Calloway. “All parties involved are contributors to that success.” Derbyshire agrees: “We have a really good staff, and they take pride in their work. They like what they do and they’re not just here to get a paycheck. They’re self-motivated.”

Calloway has high praise for his boss. “Joe tries to make himself part of the process, not just someone in the office,” he says. “He rolls up his sleeves, and the operators see him out there. He’s not afraid to do the same job they’re doing.”

They agree that constructive criticism is important. “If a guy makes a mistake, I don’t jump all over him,” says Derbyshire. Calloway adds, “If you see something that isn’t correct, you offer a solution to the problem.”

Future challenges

Derbyshire says the next step is to finish addressing issues with infiltration and inflow. They have purchased a camera to inspect the collection system, have lined the manholes, and have slip-lined the pipes that were in the worst condition.

They would also like to explore the beneficial reuse of biosolids. At present, sludge from the SBR tanks is wasted at a rate set by the operations staff to two aboveground concrete aerobic digesters. Supernatant from these is returned to the head of the plant. Biosolids from the digesters is sent to asphalt drying beds or to a Somat screw press for dewatering. The dewatered material is landfilled.

“Our future goal is to have a tri-county biosolids facility,” says Calloway. “It isn’t cost-effective to build a facility for a small plant like ours. It’s an environmental issue, and there are uses out there for the material.”

As for the ENR process, Derbyshire says the plant is reviewing the best way to meet the future permit requirement of 0.3 mg/l total phosphorus. “We will have to do this in the next three years, for the new permit in 2014,” he says. “We won’t add more plant capacity, but will tweak the current process for better phosphorus removal.”

Derbyshire advises other plants to have a good working relationship with their consulting engineers. “This is critical, and it goes both ways,” he says. “You have to know what you’re talking about if you want the consultant to listen to you.”

Says Calloway, “You have to really analyze your wastewater system. You could have a great system, but everything is interrelated. So, wherever you have a weakness is going to create a problem somewhere else.”