The project at EPCOR’s Gold Bar Wastewater Treatment Plant in Edmonton, Alberta involved developing a comprehensive automated operational strategy for addressing a key bottleneck at the plant: the thickener/fermenter tanks. SMA Consulting and Cybertech Automation worked with EPCOR on simulating the operations of the tanks to allow EPCOR to test various strategies for handling the loads safely.
The Gold Bar plant treats over 100 billion litres of Edmonton’s wastewater every year. The city’s growth and its Combined Sewer Overflow (CSO) Control Strategy is steadily increasing this amount. The plant is set to increase its peak daily loading requirements to 1.2 billion litres or more. The plant therefore faces great pressure to treat as much wastewater as possible while minimizing the impact on the river and surrounding region.
The plant is surrounded on three sides by public parks, and on the fourth by the river. The approach used in this project – developing a draft strategy and testing via simulation – improved the treatment capacity of the existing plant without immediately requiring the construction of additional infrastructure. New infrastructure could have cost up to $15 million and taken at least a year to design and build.
Virtual, not real, risks
Because the development and testing of the operational narrative was undertaken within the confines of a simulation model, it meant that all of the risks were virtual, rather than occurring under a live flow test. Potential issues that came up in the simulation could be dealt with and thoroughly tested in the simulation.
Cybertech drew on its experience with the petroleum industry to suggest a new method for developing a wastewater strategy. The company’s process controls staff were embedded in a team of EPCOR operators and managers.
Once a draft strategy was in place, SMA developed a combined discrete event and continuous simulation to capture the solids flow in the system using real minute-by-minute input data. They incorporated both the new automation system and new strategies for operators.
Balancing massive fluctuations
Developing the new strategy required balancing: (1) massive fluctuations in input volume and density; (2) biological processes in the fermenter tanks, which are time-dependent and can be dangerous if mishandled; (3) the multiple operating modes of the thickener/fermenter tanks; (4) the constraints on total output volume, which are themselves impacted by the biological processes in the digester tanks; (5) the constraints on instantaneous output volume, which must maintain a certain ratio with other sources of flow; (6) the possibility of operator intervention to deal with an emergency or maintenance; and (6) the realities of operation, such as operator error and equipment usage.
Simulating the strategy under the different scenarios required 16,000 lines of code and produced 24 million total pieces of data. The data were analyzed and visualized to provide hour-by-hour insight into an entire month’s worth of operation for each scenario.
The direct results of the control upgrades have been a 1.5% increase in solids concentration for the digester feed, equating to it having 30% higher capacity. cce
Gold Bar Thickener/Fermenter Control Upgrade
Award-winning firms (prime consultants and structural
SMA Consulting and Cybertech Automation (Mohammed Al-Bataineh, P.Eng., Holly Parkis, Kevin Yachimec).