Algae water treatment strategyTo preserve the health of Muscatine’s watershed and of communities downstream, the Iowa Department of Natural Re...Algae water treatment strategy
To preserve the health of Muscatine’s watershed and of communities downstream, the Iowa Department of Natural Resources requires water treatment plants to limit the amount of nitrogen and phosphorous in the water they release. Beginning in late April and continuing through September, the Muscatine Water and Resource Recovery Facility will pilot using algae to remove these nutrients in an effort to save both money and energy.
About 10 years ago, Muscatine Water and Resource Recovery Facility Director Jon Koch saw algae used to treat wastewater in a graduate project in progress at Iowa State University. Now, the company Gross-Wen Technologies has brought the method to market as the Revolving Algal Biofilm System.
The system uses large conveyer belts suspended vertically in wastewater treatment tanks to cycle algae through the wastewater. With each pass, algae remove some of the nitrogen and phosphorous from the water. Once enough algae have built up on the conveyer belt, it gets harvested and replaced with new algae. The water treatment plant can sell the harvested algae for a number of uses, such as serving as an all-natural fertilizer or getting converted into aviation fuel.
Before treated water gets released back into the watershed, the facility adds oxygen to it to benefit aquatic life. Because the process of putting the algae through the water aerates the water without using a lot of energy, it can help reduce the amount of electricity and money it takes to treat wastewater. It also slows the buildup of struvite, caused by high concentrations of certain minerals, on wastewater treatment equipment, reducing the amount of work and expense the plant must do to get it off of their machines and pipes.
For all these reasons, Koch considers it a promising technology: “This will act to remove nitrogen and phosphorous, which we are required to do. It adds oxygen, which we already do, but with very little energy input, which saves us money, and it’s a natural process.”