As one of the most important chemicals and fertilizer sources, ammonia has a worldwide annual production of 150 million tons, and is mainly produced by the conventional high temperature and high-pressure Haber-Bosch process, which is responsible for the massive energy consumption and CO2 emissions. Here, a novel cost-effective flow-electrode capacitive deionization (FCDI) unit combined with a hydrophobic gas-permeable flat-sheet membrane contactor (designated as “CapAmm”) is described and used for efficient ammonia recovery from wastewaters. During the operation, ammonia undergoes migration across a cation exchange membrane and selective accumulation in the cathode chamber of a flow electrode followed by transformation to dissolved NH3 with subsequent stripping via membrane contactor and recovery as ammonium fertilizer (for example, as (NH4)2SO4). The CapAmm cell exhibited excellent ammonia removal efficiency (~90%) and recovery efficiency (~70%) under a low energy consumption (~10 kWh Kg−1 N). These findings suggest that the CapAmm technology has the potential for the dual purposes of cost effective salt removal and ammonia recovery from wastewaters, with greater stability, better flexibility and greater energy efficiency than other methods.

Capacitive membrane stripping for ammonia recovery (CapAmm) from dilute wastewaters

256th National Meeting (2018)

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