The city of Detroit Lakes, Minnesota, was faced with one of the state’s most stringent nutrient limits for its planned new wastewater facility: a 94% reduction from the previous plant. The reduction was directed by the Minnesota Pollution Control Agency to preserve area water quality in neighboring Lake St. Clair, which was experiencing algal blooms from phosphorus. Like many municipalities, Detroit Lakes also had to deal with a complex mix of aging infrastructure, population growth, new regulations, funding challenges and environmental considerations.

The engineering firm of Short Elliott Hendrickson worked with the Detroit Lakes Public Utility on various options to identify the most cost-effective, high-performing approach to meet the new limits and to replace the 60-year-old plant. This video below walks through the history of the facility and what went into the planning for the new plant’s engineering and design. It also provides an overview of the wastewater process at the plant from start to finish.

In addition, the video goes into detail on the membrane bioreactor complex and the hollow-tube membrane filters. Achieving low levels of phosphorus requires membranes to physically separate solids, and the MBR membranes replaced two traditional wastewater processes, clarification and filtration. The end result: a better level of treatment in a smaller footprint, which was a requirement of the new plant site. The new plant accommodates 2.2 mgd of wastewater.

Since the MBR went online, the facility has performed better than expected and was below the phosphorus limit.