Ammonia recovery from wastewater using a bioelectrochemical membrane-absorbed ammonia system with authigenic acid and base

Ammonia recovery from wastewater was achieved by developing a bioelectrochemical membrane-absorbed ammonia system with authigenic acid and base. With the microbial electrolysis desalination, the cathode chamber of the system produced base to raise wastewater pH value and convert ammonium to free ammonia, and the acid chamber simultaneously produced acid to supply the absorption chamber and recover ammonia via membrane absorption. Ammonia was finally recovered as (NH4)2SO4 in the authigenic acid solution. The removal and recovery efficiencies of ammonia were up to 97.3 ± 0.5% and 68.1 ± 3.4% with low initial ammonium concentration (20 mM), respectively. Both high applied voltage and low initial ammonium concentration could accelerate the ammonia recovery, while the exorbitant salt concentration in the desalination chamber could delay the ammonia recovery. The energy consumption of this system for ammonia recovery was 2.91 kWh/kg-N, which is relatively low compared with some reported processes. The results demonstrate that the developed system has the potential for energy-saving ammonia recovery from wastewater.