Discipline: Technology and Engineering
Subcategory: Environmental Engineering
Elena Lopez - University of Southern California
Co-Author(s): Heyang Yuan and Zhen He, Virginia Tech
Nutrient pollution is a widespread environmental problem caused by the discharge of excess nutrients, i.e., nitrogen and phosphorus. In this study, we use bioelectrochemical systems to remove and recover nutrients from wastewater in the form of struvite and achieve multiple benefits. First, the recovery of nutrients will limit the adverse effects of eutrophication while producing a beneficial fertilizer product for the agricultural industry. Second, this approach enables the integration of bioelectrochemical technologies like microbial desalination cells (MDCs) with conventional wastewater treatment processes to improve its sustainability. A four-chamber MDC was constructed to test the feasibility of struvite precipitation from synthetic wastewater. Ammonium and phosphate ions would, in theory, migrate across the ion exchange membranes and be concentrated in the second chamber. After one month of start-up, the MDC produced a stable current of 14.0 mA for a hydraulic retention time (HRT) of 16 hours and a stable average current of 14.6 mA for a 24-hour HRT. Influent and effluent chemical oxygen demand (COD), pH, ammonium and phosphate concentrations were monitored for both 16-hour and 24-hour hydraulic retention periods. Based on the successful concentration of ammonium and phosphate ions, the concentrated solution containing ammonium and phosphate could be transferred to an external bottle and precipitated by adjusting the pH and adding magnesium. The influent COD concentrations and the hydraulic retention times are expected to exert a strong influence on MDC performance and would be examined in the following studies. Based on the high electrical current generation and nutrient recovery concentrations, theoretically, it is expected to have struvite precipitation, which would encourage further development to improve the potential within the MDC and wastewater treatment nexus for larger scale applications.
Funder Acknowledgement(s): I acknowledge the support of the National Science Foundation through NSF/REU Site Grant EEC-1359051.
Faculty Advisor: Zhen He, firstname.lastname@example.org
Role: Throughout the progression of the project, I worked with my graduate student mentor, Heyang Yuan. He advised me throughout the process; however, I took part in building the microbial desalination cell, making the solutions and changing them regularly, as well as monitoring the reactor's performance daily, and making adjustments as deemed necessary. Additionally, I collected and interpreted data, making the necessary figures in order to convey my findings through a poster presentation at the undergraduate research symposium held at Virginia Tech, in an oral presentation, and a written report. I conducted this research throughout the 10 weeks that I was at Virginia Tech through the REU program this summer; however, thereafter my research mentor has continued to collect more data.