Simultaneous desalination and ammonia recovery using microbial electrolysis desalination and chemical-production cell: A feasibility study of alkaline soil washing wastewater

The high concentrations of ions and ammonia nitrogen (NH 3 −N) in soil washing wastewater can remarkably affect ecosystem balance. This study aims to prove the feasibility of using alkaline soil washing wastewater as inlet water of microbial electrolysis desalination and chemical-production cell (MEDCC) to desalinate and recover NH 3 -N, from the views of performance and mechanism. The system could obtain desalination, and NH 3 -N removal efficiencies of 73 ± 7% and 85 ± 3%, respectively, within 12 h at the maximum current density of 9.8 ± 0.1 A/m 2. Importantly, 82.5% of the removed NH 3 -N could be recovered in the form of NH 3 ·H 2 O. The addition of electrochemically active bacteria in the anode chamber of MEDCC improved desalination and NH 3 -N recovery efficiencies by strengthing electric field. Bioenergy provided 58% of the total energy consumption, forming an energy-saving method for soil washing wastewater treatment. Alkalization pretreatment and acid immersion could reduce precipitation from membranes to improve desalination performance and reduce energy consumption. From the standpoint of the mechanism of desalination and NH 3 -N recovery, the MEDCC is expected to have the potential to simultaneously complete desalination and NH 3 -N recovery in alkaline wastewater with low energy consumption.