When the Florida town of Davie built its new water reclamation facility with a membrane bioreactor, the operators had no experience with the technology.

They did have substantial experience in the wastewater treatment industry, and that enabled them to bring the plant online smoothly, delivering high-quality effluent from the start. After 3 1/2 years in operation, the plant treats an average of 1.4 mgd, up to 70 percent of it delivered to customers for reuse in landscape irrigation.

“In starting up a brand new facility, besides learning the equipment and developing operating procedures, we were faced with having no support structure on site,” says John McGeary, chief operator. “We had a maintenance shop, but no tools, equipment or supplies, and limited spare parts. It was the same with the lab. We had specified some equipment but it was not stocked initially.

“Next, we had to do subtle upgrades and modifications, like adding signage, installing lockout/tagout stations, adding hoses and reels, placing lockers for personal protective equipment, building the Material Safety Data Sheet collection, deciding where to install valves and sample ports, setting up an office, and more. Having an experienced staff was extremely helpful.”

The team’s success has been recognized with the 2016 David W. York Water Reuse Facility of the Year Award (1 to 5 mgd category) from the Florida Water Environment Association.

Securing the resource

The fast-growing town of Davie (population 96,000) lies about 10 miles inland from Fort Lauderdale. Davie is home to several institutions of higher education, including Nova Southeastern University, Broward College, and satellite campuses of Florida Atlantic University and the University of Florida. The Bergeron Rodeo Grounds, next to the town hall, is a stop on the national professional rodeo circuit.

The history of the water reclamation facility goes back to 2007, when the South Florida Water Management District (SFWMD) adopted the Regional Water Availability Rule, requiring utilities to develop alternative water supplies to meet future demands and minimize impact on aquifers. For the town of Davie, that meant 0.6 mgd reduction in the available water supply.

After a thorough needs assessment, town officials determined that a 6 mgd brackish water treatment facility and a 3.5 mgd reclaimed water facility would be needed by 2013. The brackish water reverse osmosis plant reduced withdrawals from the freshwater Biscayne aquifer by instead drawing from the deeper Floridian aquifer.

Both new treatment facilities were built in the same complex, which also includes town Utilities Department administrative offices. The town also operates an older water treatment plant and a 5.5 mgd secondary wastewater treatment plant with three contact stabilization packaged units, sending effluent to the nearby city of Hollywood for reuse and ocean discharge.

Efficient process

The water reclamation facility was designed and built by AECOM; Ovivo supplied the MBR. Influent from two pump stations first enters the headworks, passing through two 23 mm rotating drum screens (Huber Technology) and then a cyclonic grit removal system (Fluidyne Corp.).

A biofilter (Evoqua Water Technologies) controls odors from the headworks. “It doesn’t use harsh chemicals,” says McGeary. “We fill it with plant food. The media develops a biomass that consumes the hydrogen sulfide. That is followed by an activated carbon absorber (Evoqua). We just don’t have odors.”

From the headworks, the flow moves to two covered anoxic basins for denitrification. It is then pumped to an aeration zone where nitrification occurs. The blowers are controlled on a feedback loop based on a programmed dissolved oxygen setting.

In the MBR channels, aeration continues. A thin microbiological film on the membranes aids BOD and TSS removal. “Part of the startup stage of the MBR process is to build that biofilm on the front of the membranes,” says McGeary. “At startup, the effluent is good, but it continues to get better as you build the biomass.

“We regulate the flow through the membranes with pumps controlled by variable-frequency drives. If the level goes up in the anoxic tanks, then the system pumps more. If the level goes down, it pumps less. Our pumps are on the discharge side of the membranes; we pull the flow through the system. Our favorite feature is that we don’t have clarifiers. We’re not dependent upon settleability. We don’t have to worry about filaments. We don’t have to worry about cleaning weirs.”

On to reuse

The mixed liquor suspended solids not processed after the MBR flows by gravity back to the anoxic basin. The permeate goes through a TrojanUVFit disinfection system. The finished water is then sent to reuse storage and then on to customers; excess over customer demand is injected down deep wells.

Solids are wasted to a 400,000-gallon two-stage aerobic digester. A membrane biothickener in Stage 1 continuously removes water, thickening the material from 1 percent to 3 percent solids. Aeration continues in Stage 2. The material is then delivered to a rotary press (Fournier Industries) to dewater. “The press is self-contained,” says McGeary. “The solids and the polymer enter a mixing chamber and then go into the press.”

An automatic system loads truck trailers with finished Class B biosolids for transport to farms for land application. Contractor H&H Liquid Sludge Disposal handles hauling, site permitting and application for biosolids from both the town’s treatment plants. “We also have permits to send material to lined landfills or to residuals management facilities,” McGeary says.

Disinfected effluent is sent to two storage tanks designated “reclaim” and “reuse.” The difference between the two is that if the process becomes upset, the connection between the tanks is severed and effluent is delivered only to the reclaim tank, from which it is pumped down the deep wells.

“If turbidity and disinfection are good, then the two tanks are interconnected and we pump reuse to customers on pressure demand,” says McGeary. “We maintain pressure at 70 psi, and customers use what they need. If the level goes up and the tanks are full, then the deep well pumps come on. Our usage can vary greatly. If it rains five days in a row and nobody uses any water, that’s when the deep wells come into play.”

Major reuse customers are the University of Florida Agricultural Testing Center, which abuts the plant property; Nova Southeastern University across the street; and a golf course down the road from the plant. The distribution system has been extended to a town park and a town golf course, but neither receives reuse water because capacity is insufficient.

In the near future, an additional wastewater pump station will be rerouted to the reclamation plant, raising its average flow to about 2 mgd.

Meeting the challenge

MBR technology challenged the operations team, which McGeary joined shortly before startup. He holds a Class A Wastewater Operator license and previously spent 33 years with the city of Fort Lauderdale, ending as chief operator of the city’s 55 mgd regional treatment plant. He was also captain of a seven-time state champion Operations Challenge team.

His staff members are:

• Scott Hull, plant operator II, Class B, 35 years in the industry, Operations Challenge team member
• Charles Arline, plant operator II, Class B, 35 years, former superintendent at another utility
• Todd Tysinger, plant operator 1, Class B/C, 20 years
• Jewerl Foster, plant operator 1, Class C
• Walter Fletcher, plant operator trainee
• Gregory Cavicchia and Anthony Tristram, utilities maintenance mechanics
• Cynthia Doyon, compliance and efficiency manager

“Other than a small pilot plant here and there, I believe we were the first MBR in our county,” says McGeary. Ovivo provided classroom training during the late stage of construction, and technical representatives from the company were on site during startup. AECOM, as the facility designer, also provided training.

“There was excitement in being at a place that had never been in service before,” McGeary says. “Most everybody starts a career in a place that’s well established. We were not. It was up to us to set the parameters and build the new standard operating procedures.

“We started in a half-mode with just one aerator and one anoxic tank because we only had one pump station feeding the plant in the beginning. That gave us a chance to learn at lower flows. The process worked quite well. I would say most of our startup headaches were just minor bugs, like electrical and plumbing problems.

“Between Ovivo, AECOM and our own maintenance staff, we got everything fixed and got the plant running smoothly. We were extremely pleased with the quality of the effluent, even right away. We started by only discharging to the deep wells until we had a good track record. We ran that way for six months to make sure we had a good quality consistency before we began to push reuse water out to customers.”

Keeping it running

Along the way, the team built the SOPs based on a U.S. EPA model that includes seven phases for each procedure. An in-house lab allows operators to perform tests for process control. Samples for compliance testing are sent to a certified laboratory.

The team has developed an extensive safety program. All members are trained in first aid and in the use of the plant’s automatic electric defibrillators. Team members and compliance officer Doyon do full walkthroughs of the plant every two months to identify issues that need attention. All SOPs include a safety component. The fire alarm and suppression system is thoroughly tested annually. Training courses for continuing education credit are offered periodically to staff by vendors, the city of Fort Lauderdale safety training bureau, and the local operators association.

For McGeary and his team, starting and running the plant has been a good ride and a source of satisfaction. “Once we moved the influent pipe here from the other plant, it was the point of no return,” he says. “We had to learn quickly how to get things right. The plant works very well. It’s very consistent. If you have the machines running right, they will produce results for you.”

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Keeping it green

The Town of Davie Water Reclamation Facility and the adjoining brackish water treatment plant and offices operate in keeping with the town’s larger focus on sustainability, embodied by the slogan: Make Davie Clean Through Green.

“When this facility was designed, it had a lot of green features built in,” says John McGeary, chief operator. The buildings have multizone heat pumps for air conditioning. The lights are on motion sensors so that they turn off when spaces are unoccupied.

“We capture all the rainwater here on site,” says McGeary. “We have retention areas, and they are interconnected. An underdrain takes all the rainwater and percolates it back into the aquifer. We even capture the rain from the roofs and parking lots. This facility is not an aquifer drawer but an aquifer adder.”

In general, the town acts affirmatively to promote water conservation. Residents can pick up low-flow showerheads and sink faucet aerators. A town park hosts Broward County’s annual Water Matters Day, where water utilities and product vendors set up exhibits — as many as 90,000 people attend.

Town utility officials also meet with homeowner associations to advocate wise use of water and discuss topics such as best practices for irrigation. “Water conservation is a big deal,” says McGeary. “It is becoming more important in South Florida, as consumptive-use permits from the Biscayne Aquifer are being restricted.”