In situ utilization of generated electricity for nutrient recovery in urine treatment using a selective electrodialysis membrane bioreactor.

Recovering resources, especially energy and nutrients, from source-separated urine, is attracting increasing interest. By integrating electrodialysis into an electrochemical membrane bioreactor, a novel, selectively electrodialysis membrane bioreactor (EDMBR) was developed for the treatment of source-separated urine and nutrient recovery. Before injection into the EDMBR system, the diluted urine was pretreated by ammonia stripping. The concentration of ammonia in the urine decreased from 1292.2 ± 47.5 mg/L to 235.1 ± 5.7 mg/L upon stripping, denoting an 81.8% ammonia removal efficiency. Phosphate and sulfate recovery from urine were then achieved in situ , utilizing the electricity generated by selective electrodialysis in the EDMBR. In this EDMBR system, which was fed with treated urine after stripping, a maximum power density of 23.5 W/m 3 was obtained at an external resistance of 1000 Ω. Consequently, 97.4% of the NH 4 + , 76.7% of the PO 4 3− , and 94.5% of the SO 4 2 − was removed, while 65% of the phosphate and 54.9% of the sulfate (based on their amounts in urine after stripping) were recovered as a concentrated solution. Moreover, other salts, especially NaCl, were selectively retained as brine, indicating that the EDMBR shows promise for urine desalination. This study demonstrates a new strategy for nutrient separation and recovery from source-separated urine by utilizing bioelectricity generated in situ . [ABSTRACT FROM AUTHOR]