Back to the Land

A meticulous staff operates an award-winning plant in Bonita Springs, Fla., that recycles all wastewater for irrigation and bios.
Back to the Land
The Bonita Springs Utilities East Wastewater Reclamation Facility provides tertiary treatment for a population of 30,000. (Photography by Greg Kahn)

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Cliff Morris is like a man with a new car. As chief operator of the three-year-old East Water Reclamation Facility in Bonita Springs, Fla., he’s as proud as can be of his staff, the plant, and the pristine effluent that is 100 percent recycled.

Started up in April 2007, the membrane bioreactor plant has functioned flawlessly, thanks to the TLC of Morris and his conscientious staff. Professionals from around the world have come to see it.

“I can’t take credit for it,” Morris says, “but it’s the easiest plant I’ve ever had to supervise.” That’s saying a lot for someone who has managed treatment plants in South America and Guantanamo Bay, among other locations.

“After all these years bopping around the industry,” he says, “I feel like I’m driving a Ferrari.” The facility has won state and national engineering awards for its design by the engineering firm of CH2M HILL.

Public sensitivity

The plant wasn’t easy to build. Constructed to supplement the agency’s 7 mgd West Water Reclamation Facility eight miles away, the East WRF was placed on 470 acres along Interstate 75, but complaints from a neighboring trailer home community forced construction to the rear of the property. Wetlands had to be restored and a bird habitat created, requiring close control of all plant lighting, noise and odors.

The odor-control system, consisting of covered areas and a trio of bio-towers from Bioway ( LLC), is very effective. “People visit and comment on the fact that nothing smells,” Morris says.

Just under 4 mgd flows from a collection system that includes 315 lift stations. Wastewater is channeled through a 6-mm rotating band screen (Ovivo), and a manual bar screen. A cyclone grit remover and classifier follow, and the water then passes to a 1.25 mgd equalization tank. The tank features blowers (Dresser Roots) and a Jet Tech jet aeration system (Siemens Water Technologies Corp.) to keep the contents agitated.

From the EQ tank, the wastewater undergoes additional screening and then enters the modified Ludzack-Ettinger biological process, consisting of an anoxic basin divided into two trains, and an aerobic basin divided into three trains. Each train contains three zones, separated by baffle walls. The zones are equipped with Flygt (ITT Water & Wastewater) mixers, Hoffman blowers (Gardner Denver), and Sanitaire (ITT Water & Wastewater) fine-bubble diffusers.

“It’s a step-down design with dissolved oxygen probes before and after the process,” says Morris. “We have automatic controls on the blowers and valves to automatically turn down the airflow and maintain proper biological activity.”

The four membrane trains are the ZeeWeed systems from ZENON, a Division of GE Water & Process Technologies. There are five cassettes per train, and each train is designed to process 1 mgd. Each cassette has 48 modules, manifolded together, and is connected to a common permeate header linked to a dedicated air separation tank and permeate pump. A small vacuum produced by the pump draws water through the membranes and leaves mixed liquor suspended solids on the outsides of the membranes. Air scour blowers (Aerzen) agitate the membrane surfaces to prevent biomass from accumulating.

Fully recycled

“The MBR technology is amazing,” Morris says. “It takes the place of clarifiers and filters.” The plant design allows for two recycle flows. The mixed liquor recycle stream feeds the membranes at 4,000 to 7,000 ppm of suspended solids and is concentrated after filtering and returned to the head of the aerobic basins. The second stream consists of a nitrified recycle and is returned to the anoxic basins.

The East WRF uses multi-channel sodium hypochlorite to disinfect the effluent. But that’s not the end of the story. The plant recycles 100 percent of its effluent. The clear water is pumped to a pair of 4-million-gallon lined ponds, one for reject and one for recycle.

Water is transferred to the reject pond only in rare cases where there may have been a glitch somewhere in the treatment process. That water is treated again. The water in the recycle ponds joins water from the West WRF and is sold to a private company, which distributes it as irrigation water to local golf courses. A small portion of the reclaimed water is returned to the East plant for process water.

The water quality is simply magnificent. In the lobby of the plant, Morris and his staff maintain a 200-gallon aquarium filled with effluent where healthy fish swim around and attract interest from plant visitors.

“The last few months, I’ve taken grab samples before the disinfection step, and it’s pretty amazing,” Morris says. “We look for fecals and suspended solids, and we haven’t had a hit yet. The membranes do a great job.”

Membrane care

Morris says the key is protecting the membranes by keeping them and the screens ahead of them clean and functioning. “We clean all our membranes twice weekly with sodium hypochlorite, and every third clean is with citric acid,” he says.

The cleanings are triggered automatically by the plant’s SCADA system, and staff members are careful not to damage membrane fibers as they work around the units. “We clip everything (pens, sunglasses, tools) so they don’t drop on the fibers,” says Morris. “In three years, we haven’t had a broken fiber.”

Biosolids are not wasted either. After aerobic digestion, a Vulcan rotary drum thickener brings them to 1.5 percent solids, and they are transferred to a GEA Westfalia Separator centrifuge that produces material at 19 to 20 percent solids. A natural-gas-fired Andritz dryer processes the material into 93 to 94 percent solids Class AA pellets.

Two 40-ton-capacity silos store the pellets, and a drive-through scale station dispenses the pellets onto trucks that convey them to a local fertilizer manufacturer. It represents yet another revenue stream for Bonita Springs Utilities.

The agency used to sell the pellets to a wholesaler who sold them to farmers, but the current arrangement creates a steady demand for the material. “The dryer is a good unit,” Morris says. “It puts out a real nice product.” No odors. No outfall. No landfilling of biosolids. “Everything gets recycled here,” says Morris. “That’s a good thing.”

It’s automatic

As pleased as he is with his MBR system, Morris is just as enthused about his plant’s controls. The system, made up entirely of Allen-Bradley (Rockwell Automation) components, is both powerful and loaded with redundancy.

“We have lots of PCs, and both primary and secondary PLCs,” says Morris. “We have four electrical rooms, all with PLC racks. All our probes for DO, nitrates, pH, and total dissolved solids feed into the system.” Morris says a key to success was that the system integrator (Revere Control Systems of Birmingham, Ala.) worked with all subcontractors and equipment suppliers so that all controls and automation throughout the plant are tied together in a single system.

Fiber optics connect all the agency’s water and wastewater treatment plants, and a Category 5 hurricane center built next to the East plant also hosts all controls, so that any and all of the plants can be operated from it in a bad storm. “There are multiple places to monitor all operations,” Morris says. Two separate electrical sub-feeds to the plant, and an on-site 1,750 kW generator (Caterpillar), provide even further redundancy.

Staffing and teamwork

Morris’s enthusiasm transfers to his staff, which includes electrician/technician Scott Becker, in charge of the automation system; maintenance technician Jim Davis; biosolids technicians Mike Fedczak, Bruce Keller and Dennis White; and operators Chad Peets, Brian Daniels, Steve Frates and Martin Hennigan, all Class C; and Neil Harden and Mark Sweitzer, Class A. “Everybody is proud of this plant,” Morris says. “Staff members find things on their own to make the place better than it was when we started up.”

He points to a team project to clean and refinish floors in portions of the plant so they absolutely shine. “In the biosolids room, we have a policy of no dust,” Morris says. “You could eat off the floor in there.

“I admit I’m a clean-freak. Spit-and-polish is all I ask. When I started out, I was a micro-manager. Not anymore. Our people have the authority to make decisions. We demand professionalism here and we get it.”

The plant is required to have a licensed operator on site only 16 hours a day, but Bonita Springs has chosen to staff it around the clock. Much of the staff is cross-trained for wastewater and drinking water. Morris himself holds Florida Double A certification in both. “Actually,” he observes, “running a membrane plant like this is almost the same as running a water plant.”

Morris says morale is aided by the flow of visitors who come from around the world, interested in the MBR process. “Plus,” he says, “I’ve given papers and webinars on the plant and the process. We’ve received a lot of accolades. There’s a ‘wow factor’ here.”

Pride and teamwork carry over into activities outside the plant. “Six of us ride motorcycles,” Morris says. They go on rides together on weekends and during off hours. “We’re proud of what we do, on and off the job,” Morris says. “Everybody accepts each other.”


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