According to the Madison Water Utility, throughout 2017 the city of Madison, Wis....
Reliable, cost-effective wastewater treatment and recycling in Orlando, Fla
The residents of Orlando, Fla., and nearby communities are more likely to see lightning strike than their toilets run dry. Extensive high-tech upgrades, including new automation and control systems, at Orlando’s three advanced wastewater treatment plants have assisted city staff in their quest to process more sewage and graywater effectively and reliably.
As growth continues to put increasing demand on Florida’s freshwater supplies, more communities in and around Orlando are counting on reclaimed water to meet many of their residential and business needs. Water shortages, stringent environmental protection laws, surging sewer service demand, fewer qualified workers and a virtual rate freeze are the major challenges placed on a smaller yet smarter wastewater management team.
“It’s expensive and tough to find experienced and qualified people in this business. Automation has solved that issue for us,” said Industrial Automation Manager Bill Wood, as he walked the southern end of the city’s Iron Bridge Regional Water Reclamation Facility. “It used to take a dozen or more operators to run this plant alone. Even though the operation has grown significantly in scope, running the plant now is more manageable and precise thanks to the vision of Orlando’s public works and environmental leadership.”
The Iron Bridge plant was built in the 1980s to treat about 5 million gal of wastewater per day. After several modifications and upgrades, it now can treat and reclaim up to 40 million gal in 24 hours.
“The automation simplifies operators’ decision-making. All the information they need to run the plant is at their fingertips no matter where they are,” said Wood, whose team has installed a totally integrated Siemens automation and energy system to assist in the operations and power distribution throughout the plant.
Standardized on the Siemens S7-300 programmable logic controller (PLC) and Profibus and Industrial Ethernet networks, the automation platform controls everything from the flow of electricity to the amount of reclaimed water being discharged safely from the plant. Treated water is sent to the Little Econ River and the Orlando Wetlands Park, while pipelines also deliver purchased reclaimed water to residential neighborhoods, golf courses, citrus groves and other customers as far as 20 miles away.
“Our daily objectives focus on keeping the toilets flushing and meeting the growing demand for wastewater treatment and reclaimed water across the region,” Wood said. “We can’t reach those goals without the reliability and flexibility provided by [these] automation and communication systems.”
Eyes & Ears of the Plant
Iron Bridge is a 320-acre operation—a series of treatment processes that must be monitored and managed closely. The PLC at the master pumping station reads real-time intake levels and signals variable-frequency drives to speed up or slow down the eight 400-hp pumps designed to handle peak loads of wastewater rushing into the facility through an 84-in. pipe.
Halfway across the plant, Flowmeters measure the air being pumped into aeration tanks where organic waste is consumed by bacteria. A PLC controls the air flow and records and stores data gathered during the intricate, five-stage biological process known as Bardenpho.
Human machine interface (HMI) touch screens are located in every process station and linked to the facility-wide Industrial Ethernet network, offering operators a real-time view into every layer of the plant. Siemens WinCC SCADA software offers that same vantage on the laptops, desktops and kitchen countertops of authorized plant and city personnel.
“It used to be a real juggling act for an opera- tor to ensure that water leaving the plant through three separate exits met a variety of strict environmental standards for the river, wetlands and applications in action irrigation,” Wood said. “Now we trust Siemens automation to handle this once-intimidating task with Web-based WinCC SCADA software, integrated over our S7 platform, that provides reliable snapshots of our operation status and water conditions anytime, anywhere. Coupled with the opera- tor’s expertise, the PLCs have become the eyes and ears of the plant, and they have changed the way we do business.”
Operating Cost Control
Orlando has three advanced wastewater treatment facilities (Iron Bridge, Water Conserv I and Water Conserv 2) and 210 lift stations pumping sewage away from the homes and neighborhoods to these plants. Like most municipalities, Orlando has treated and operated each facility autonomously for decades. To reduce costs and increase efficiency, the plants were integrated.
“Rate freezes and infrastructure, inventory and labor requirements put a real squeeze on productivity, so we had to find a solution that would benefit all of our facilities,” Wood said. “Instead of having staff dedicated to a single plant, we now share our resources across the entire enterprise using Siemens automation.”
“As the treatment plant grows with the city, we simply can’t continue to staff up. It’s too costly,” said Wastewater Systems Manager Guy Mecabe, who has been instrumental in the deployment of the automation system and the Profibus and Industrial Ethernet networks. “The reach of our networks has grown 10 times over in the last two years, as we’ve expanded our ability to monitor and manage the whole system 24/7 from just about anywhere using WinCC SCADA software.”
Authorized managers, operators and technicians can view the Iron Bridge plant from any one of 10 onsite HMIs or a remote computer. They also can monitor and control operations at Water Conserv I, Water Conserv II or the lift stations throughout the city without leaving the Iron Bridge plant.
“Secure remote monitoring means I can respond to a trouble call in the middle of the night by simply tapping into any of the treatment facilities from home or wherever I am. It’s amazing,” Mecabe said.
“Because we can’t physically push the buttons that start, stop and reset processes, we’ve called on the best technology to do it automatically and reliably. It’s just one of many new cost-cutting practices we’ve initiated that are really making a difference to the bottom line,” Wood said.
“A lightning strike could instantly cut power to this plant, but all the Siemens PLCs and networks consumer with a monthly Progress Energy bill averaging $180,000. But the question of the bill’s accuracy long nagged Wood and his counterparts. As part of a re-rating plant upgrade, Siemens 9600 and 9330 utility-grade power meters were installed at the plant’s power intake and at each of the facil- ity’s switchboards and motor control centers.
“Until now, we had no way to verify the accuracy of the electric bill. The Siemens metering, linked to our networks, offers real-time consumption data and monthly peace of mind, as well as an effective way to identify the equipment power hogs in the treatment process,” Wood said. “That’s a powerful capability that we fully plan to leverage in the months and years to come.”
Code to Success
There is no secret to the successful control evolution at the Iron Bridge plant, nor is there any hidden blueprint; it is more like an open book. Wood, Mecabe and the team are more than happy to share their experience with other industry professionals like Pat Brechbill, a wastewater treatment specialist with the Cobb County system near Atlanta, who recently toured Iron Bridge.
“I’m most impressed with the amount of sys- tem information and feedback reports available, and how it’s easily and quickly displayed using Siemens HMIs and WinCC,” Brechbill said. “A single purple Profibus network cable has made wiring, maintaining and troubleshooting the plant easier and faster than a conventional facility. All in all, Orlando has one of the most innovative and efficient systems I’ve ever encountered.”
“I’ve seen too many treatment facilities spend lots of money on upgrades only to end up with out- dated and patchwork solutions,” Wood said.
Therefore, Wood and the Orlando team have designed an upgraded treatment system with the future in mind. “Every piece of automation and control equipment and software—from the PLCs and HMI touch screens to the SCADA that provides
the graphical, insightful views into the plant—is modular in design, so we can keep adding new functionality and applications along the way,” Wood said. “We could run this entire plant on two Siemens PLCs, but we’ve put a PLC in every process station to minimize our risk through a distributed architecture that’s given us the ability to do whatever we need to do when demands change in the future.”
Even the minimal hardwired functionality in the plant is future-proofed with a recent addition to the plant’s automation platform: a multipurpose workhorse called SimoCode. “SimoCode is a very flexible product,” Wood said. “We’ve actually changed our specifications to include [one] in every starter bucket so we can remotely check the status of smaller feeder breakers, as well as detect and reset faults over Profibus.”
SimoCode has dramatically reduced the wiring required in the motor control centers at Iron Bridge. “You can see how clean this cabinet is compared to the elaborate conduit chases with cables running back and forth in control rooms like this,” Wood said. “Instead, a SimoCode has been placed in each bucket as a piece of I/O that can easily be added and viewed on the net- work. It’s all part of a totally integrated automation solution that works seamlessly.”
“With SimoCode, I have very smart switchgear,” said Wood, who also noted the power savings and preventative maintenance benefits that the solution can deliver each month.
For Wood, Mecabe and the Orlando team, wastewater treatment is all about protecting the community and the environment. “It includes state-of-the-art automation that runs reliably for weeks, months and years, enabling us to put clear, clean water back into the aquifer with confidence,” Mecabe said.
“This is the product of our treatment plant,” Wood said, holding up a beaker full of clean water bound for the Little Econ River. “Siemens automation helps give us the confidence and information we need to secure the most important return on investment of all: the return of clean water to our rivers, streams and irrigation systems across the region. That’s special treatment.”