The Western Lake Superior Sanitary District and Donohue & Associates received a 2023 Engineering Excellence Honor Award from the American Council of Engineering Companies (ACEC) of Minnesota for the Oxygen Supply Improvements Project.

Western Lake Superior Sanitary District provides cost-effective wastewater treatment for a 530-square mile region encompassing Duluth, Minnesota, and 16 area communities and townships. The water resource recovery facility provides High Purity Oxygen (HPO) biological treatment. Its aging cryogenic oxygen production system was energy and maintenance intensive. This project used a novel sensitivity analysis to evaluate oxygen production strategies and, ultimately, select and install an efficient and robust one. The solution, a new 80-ton-per-day Vacuum Pressure Swing Adsorption (VPSA) system, is the first VPSA system producing oxygen for an HPO facility in the upper Midwest.

The new system requires relatively little operator interaction and District personnel are able to perform routine maintenance activities previously outsourced. Annual estimated maintenance cost savings are over $100,000. Other advantages include a compact footprint, mechanical simplicity, and mechanical redundancy.

The Donohue team was able to fit the new oxygen supply system in a very tight space. Since startup, the facility has been achieving excellent effluent water quality. Energy savings realized are significant; this project and others have helped the District avoid $1M of annual energy spending compared to 2013.

With this project the District was able to accommodate a recent major development reliably, cost effectively, and sustainably.

Engineering Excellence awards recognize quality engineering achievements. Entries are judged on the basis of excellence in design, the degree to which the client’s needs are met, as well as benefit to the public welfare and to engineering practices.