CAREER: Design of surface modified membranes for recovery of key fertilizer macronutrients from wastewater

The demand for the constituent nutrients of fertilizer (Nitrogen(N), Phosphorus (P) and Potassium(K)), which is already high, is expected to grow as the world population grows. The traditional technologies to produce these nutrients are energy intensive and are associated with large carbon footprints. On the other hand, these nutrients are abundantly present in wastewater and, in fact, their release into lakes and streams leads to environmental problems like excessive algal blooms and eutrophication, which requires billions of dollars for remediation. Membrane processes could play an important role in solving both of these challenges by recovering key fertilizer components and preventing their release into the environment while reducing the reliance on traditional energy-intensive processes. In this work, the investigator aims to identify and analyze the critical separation mechanisms in polyelectrolyte-modified membranes for the recovery of two key macronutrients - nitrogen (as ammonium ion, NH4+) and potassium (K+) from wastewater. The educational activities will provide mentored research opportunities to low- income, first-generation students, who are traditionally underrepresented in STEM higher education via summer workshops. Additionally, the project also aims to improve the recruitment and retention of students in engineering via introduction of a new experiential learning initiative. The investigator aims to identify and analyze the critical separation mechanisms in polyelectrolyte modified membranes that enable selective recovery of fertilizer macronutrients from wastewater under neutral pH conditions, with the goal to guide advanced membrane development. The PI’s research will analyze the role of size exclusion, charge based transport, and hydration-based separation in polyelectrolyte-modified membranes to facilitate organic/nutrient partitioning and recovery of nutrients in tunable proportions. The PI aims to develop a fundamental framework that relates membrane morphological properties to different separation mechanisms like size-exclusion, charge-based transport and hydration-based ion separation which must be synergized to achieve desirable organic/nutrient separation. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.