City of Sarasota, Sarasota, FL, USA

Sarasota, a city of 55,000 on the southwestern coast of Florida, owns and operates a facility that utilizes reverse osmosis (RO) and ion exchange (IX) processes to produce drinking water from raw water taken from wells in the Verna field, 15 miles east of the city, and the Downtown field. The facility’s RO plant produces 4.5 million gallons per day (mgd) and the IX plant produces 7.5 mgd, of which 2.3 mgd is blended bypass water, giving the facility a total capacity of 12 mgd.

Over the years Sarasota has initiated a series of projects to improve this water treatment facility, installing newer RO membranes, 1 micron pretreatment cartridge filters, high service pumps, a SCADA system, and well monitoring equipment ahead of RO equipment. Additional improvements include upgrading the seawater handling system for IX regeneration, retrofitting hollow fiber with spiral wound RO technology, and replacing a legacy control system with a late model production control system.

The retrofit of the spiral wound RO technology was designed and piloted by Boyle Engineering Corporation, a local consulting engineer, and implemented by Harn RO, a local RO OEM. Classic Controls Inc., a system integrator that works closely with Yokogawa Corporation of America, was assigned the installation of a CENTUM CS 3000 distributed control system (DCS) and FOUNDATION™ fieldbus devices. This work was completed on schedule and on budget for the city of Sarasota.

Total system integration for greater efficiency and reduced power consumption
The legacy control system at the Sarasota water treatment was fully outmoded, with an instrument panel board that relied on push buttons, selector switches, and other analog controls, as well as single loop controllers, recorders, an annunciator box, and other aging instruments. Not only was this system expensive to maintain, operations were not fully automated and it was difficult for operators to quickly assess what was happening throughout the facility and intervene in a timely fashion.

The migration to the Yokogawa CS 3000 DCS was accompanied by the installation of magnetic flowmeters, differential pressure transmitters, and other Yokogawa FOUNDATION fieldbus-enabled instruments in several key processes, and the DCS was completely integrated with all the other vendor systems throughout the facility. From modern graphic user interface (GUI) terminals in the central control room, operators are now able to get a complete overview of operations throughout the plant by viewing a single screen. Information on display includes pressure and total volume readings for the main distribution pumps, chemical feed process data, and main tank levels. From this screen, operators can drill down to view detailed information on individual processes such as the IX process, which requires a periodic rinse procedure that is fully automated by the CS 3000 system. In addition, they are able to manage devices throughout the plant by means of the CS 3000’s Device Manager tool.

The complete integration of these systems and the use of FOUNDATION fieldbus technology has made a significant contribution to operational excellence at this facility, and has significantly reduced its power consumption. It is estimated that the facility’s operating costs have been reduced by $0.21 for every gallon of drinking water produced. In addition, the RO retrofit has improved water quality.

Peter Perez, plant supervisor at the Sarasota facility, had the following to say about Yokogawa’s contributions in this project:“Our mission is always to enhance the quality of life of all residents by providing safe, reliable, effective water serviceconsistent with the vision and goals of the community. Drinking water is a lifeline of all the people. We are very proud of working in this plant to supply steady and high quality water everyday. We are very satisfied with Yokogawa’s system and products, because they are very reliable. We are striving to improve the total plant operation and we are always challenging new technology to purifying water. Currently our pilot skids are equipped with Yokogawa’s magnetic flowmeters and differential pressure transmitters, utilizing FOUNDATION fieldbus. We believe that FOUNDATION fieldbus technology allows for us further proactive maintenance to reduce operational cost.”

Classic Controls, Inc. of Lakeland, Florida, provides total solutions, including system engineering, selection of instrumentation, and process design, as well as system installation and training. In terms of systems engineering capability, the company is one of the highest qualified Yokogawa system integrators in the US.

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