Mahamalage Kusumitha Perera, a PhD candidate in the College of Engineering’s Department of Civil, Architectural and Environmental Engineering, presented his research, entitled, “Simultaneous Chemical-free Nitrogen and Phosphorus Recovery from Municipal Wastewater,” on April 2, at the American Chemical Society conference in Orlando, Florida.
Perera’s research focuses on recovering nitrogen and phosphorus from wastewater. These nutrients are essential for plant and animal growth and nourishment, but their overabundance in freshwater causes uncontrolled algae growth, destroying freshwater ecosystems. This process – called eutrophication – has detrimental ecological effects: decreased biodiversity, depleted oxygen levels, toxicity effects, and changes in species composition and dominance. Perera has been testing a technology that combines electrochemical and chemical precipitation with gas-liquid stripping to remove nitrogen and phosphorus from wastewater without using any chemicals. This innovative technology has the capability of being adapted to onsite and packaged treatment plants, which can produce fertilizer requiring minimal post-processing beyond filtration.
“Our preliminary results using this new technology in a laboratory scale using actual sewage indicate a significant removal of nitrogen and phosphorus through the use of environmentally friendly and cost-effective methods,” says Perera. “This is great news as we intend to construct a pilot scale plant to demonstrate the process.”
The objective of the study he presented at the conference was to provide a sustainable solution to nutrient pollution in the environment by recycling nutrients. Production of nitrogen fertilizer is energy intensive and production of phosphorus fertilizer from non-renewable phosphate ores produce large amounts of radioactive phosphogypsum waste. Thus, the team has demonstrated efficient nitrogen and phosphorous recovery, directly from settled sewage, by shifting the pH of water electrochemically, a process they call electrohydromodulation (EHM).
“With our process we demonstrated 88 and 97% of nitrogen and phosphorous from settled sewage with a total energy demand,” continued Perera. “We are now designing a version suitable as a septic tank add-on, to address the impact of sea-level rise on leach field performance, and applying electrohydromodulation to other water treatment applications.”
