BACKGROUND: Urine is an abundant waste product which requires energy intensive treatment processes in modern wastewater treatment plants. However urine can be utilised as fertiliser in the form of struvite. Microbial fuel cells (MFCs) are a promising technology for treating waste while producing electricity. Combining these two approaches, a 3-stage MFC/struvite extraction process system was developed and its feasibility tested in order to maximise urine utilisation in terms of electricity generation and struvite recovery.
RESULTS: In the first stage, while generating electrical energy, MFCs accelerated urea hydrolysis, which was beneficial for the struvite precipitation process in the following stage. After collecting struvite by adding magnesium into the initial effluent, the supernatant was used at the final stage for additional power and more efficient COD reduction. In total, 82% of PO43--P and 20% of COD of undiluted human urine were removed by the 3-stage system. Also 14.32 W m-3 (absolute power: 358 μW) and 11.76Wm-3 (absolute power: 294μW) of power was produced from the 1st and 3rd stages of the system, respectively, during operation.
CONCLUSION: This work shows how MFCs and struvite precipitation could be integrated for both energy generation and resource recovery from urine, leading to a more sustainable energy future.
You, J., Greenman, J., Melhuish, C., & Ieropoulos, I. (2016). Electricity generation and struvite recovery from human urine using microbial fuel cells. Journal of Chemical Technology and Biotechnology, 91(3), 647-654. https://doi.org/10.1002/jctb.4617