Town Talk: Reducing phosphorus

Phosphorus is a nutrient that the wastewater treatment plant treats every day. It is an essential nutrient for humans, animals and plants to survive. It plays an important role in cell development and usage of energy. Phosphorus comes to the wastewater treatment plant through human waste, food waste, cleaning products, industrial waste and through the soil.

The New Ulm Wastewater Treatment Plant treats phosphorus using a series of tanks collectively called a biological nutrient removal system. We provide a place and ideal conditions for the phosphate accumulating organisms to grow and reproduce while they are using the phosphorus to do so. Some of the tanks have minimal oxygen and other tanks are provided with more oxygen. There are times when a large amount of waste (organic load) comes into the plant and we lose some of this treatment. If this happens, we feed ferric chloride which binds with the phosphorus and settles it out of the system. This helps us meet our discharge limit set by the Minnesota Pollution Control Agency while the biological system is recovering from the large organic load.

The New Ulm Wastewater plant must reduce phosphorus because too much discharged into the river will have a negative influence on the fish and other aquatic life. A large amount of phosphorus will cause excessive algal growth in the body of water that affects the water quality, habitats and plant growth. Too much plant growth will decrease the amount of oxygen available to fish and other aquatic life and in turn affect the quality of life and reproduction. A large amount of phosphorus in a lake will cause a green algae bloom or blue-green algae growth.

As a homeowner, there are a few things you can do to reduce the phosphorus output from your home. Read the labels of your home and car cleaning products. Some cleaners contain a large amount of phosphorus. The ingredient list will have compounds like orthophosphate, polyphosphate and pyrophosphate. A good option would be green cleaners that are phosphate free. Another thing that you can do as a homeowner is to limit the amount of fertilizer placed on your lawn. Excess fertilizer runs into the storm sewer and into the river.


Editor’s Note: The City of New Ulm presents a weekly column highlighting activities in different departments in the city government. Once a month the city will answer questions from readers. Questions on New Ulm city issues can be sent to comments@ci.new-ulm.mn.us.


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