Wastewater Treatment Plant Process
Helping protect water quality by replacing obsolete control systems.
A large wastewater treatment plant in the United States that provides service to a major metropolitan area and its neighboring communities covering an area of 946 square miles.
The sewer overflow basins’ process control system varied widely and were no longer supported by the original manufacturer. The control system needed to not only be upgraded by integrated as well. Their key considerations were standardization, capital expenditure, and total lifecycle costs.
The city maintains eight different sewer overflow facilities that are different in size and design but apply the same water treatment process of retaining the overflow, mechanically screening out solids, and disinfecting the water with bleach. All basins use equipment that monitor flow rate and volume, collect samples, remove residual water from the basins, and clean them after a rain storm.
The basins were built over the course of 3 decades, so despite the fact that their functions were similar their process and automation control technology varied greatly. Another factor was that previous projects were completed at different times which resulted in each basin being built with different federal and state water quality standards. This caused process control systems to be updated at different times and resulted in a numerous systems at all locations. At one facility it was so bad that they had process control equipment from four different manufacturers.
With such an assortment of legacy equipment it made integration at best difficult and mostly impossible. With all the basins not on a standard platform, troubleshooting and maintenance were hindered and inventory expenses were high because multiple spare parts needed to be kept on hand for all the facilities
The city’s water and sewer department chose the Rockwell Automation PlantPAx™ Process Automation System to solve their issues. PlantPAx™ is an integrated control and information solution package that combines the capabilities of a Distributed Control System while enabling plant wide control and optimization. This scalable, multidiscipline platform helps users who need both process and sequential control to achieve lower total cost of ownership and plant wide control.
The installation of the process library and toolkit was cut in half saving approximately $120,000 in programming and systems-integration time. There was an additional $90,000 saved in factory-acceptance testing and startup/commissioning.
City officials estimated the new tools provided a 50 percent reduction in design time, contract oversight, and post-contract documentation and support. The improved diagnostics of the system allows for preventive and predictable maintenance to be done easily.
PRODUCTS AND SERVICES USED
- Plant PAx System
- FactoryTalk View SE
- Water/Wastewater Accelerator toolkit
- Stratix 8000 Switches