Phosphorus

Minnesota’s waters must be clean and healthy to sustain aquatic life and provide recreational use. Although phosphorus is a nutrient for plant growth, excess phosphorus can speed up the aging process of lakes and streams by over stimulating algae growth. Algae blooms are unsightly and create high biochemical oxygen demand (BOD) as the algae decomposes and uses up available oxygen supplies, sometimes threatening the survival of fish and other aquatic organisms.

The majority of phosphorus loading comes from nonpoint sources during high rainfall periods causing significant runoff from agricultural lands. During these high flow periods, the Minnesota Pollution Control Agency's (MPCA) monitoring data has documented that only 10% of total phosphorus comes from point sources. But during low flow or low rainfall conditions, point sources contribute as much as 64% of total phosphorus to the river basin. These point sources include wastewater treatment plants and industrial dischargers. Industrial sources of phosphorus include food processing, phosphatizing, and cleaning operations.

• Are you required to develop a Phosphorus Management Plan? MnTAP can help you and your industrial users identify opportunities to reduce phosphorus use.
• Is your city facing a phosphorus limit in a few years? MnTAP can help you reduce the phosphorus in your influent by working with your industrial users to reduce their phosphorus discharges

Phosphorus Management Planning
Developing a Phosphorus Management Plan (PMP) will help you understand your wastewater treatment facility's (WWTF) influent and effluent phosphorus levels, and how those levels may be reduced, with potential cost savings.

The PMP Development Resources have been designed by the Minnesota Technical Assistance Program (MnTAP) and the MPCA to make the phosphorus management planning process easier for all WWTF operators.

The resources can help you:

• Understand how commercial, industrial, institutional, domestic and water treatment plant sources contribute phosphorus
• Assess the potential for phosphorus reduction and evaluate strategies to reduce phosphorus levels in your WWTF discharge
• Prepare a thorough and well-organized PMP

In the future, the Minnesota Legislature may pass a statewide effluent phosphorus limit for all POTW's. In the meantime, when a wastewater treatment plant renews its permit, the Minnesota Pollution Control Agency (MPCA) may give the facility an effluent phosphorus limit or require a PMP.

Identifying and Reducing Sources of Phosphorus
Business users—commercial, industrial and institutional operations—likely to contribute phosphorus to the WWTF include agricultural co-ops, car/truck washing facilities, dairies, food processing plants, meat packing and locker plants, metal finishing facilities, municipal water treatment plants that add phosphorus to drinking water, nursing homes, restaurants, schools and other institutions. WWTF operators should identify these and other phosphorus sources and work to reduce phosphorus wherever possible.

A WWTF should consider working with its business users on phosphorus reduction strategies. MnTAP has a number of resources that can provide information on phosphorus sources and reduction strategies for different business sectors and examples of companies saving money through these activities.