Hydrogen production and ammonium recovery from urine by a Microbial Electrolysis Cell

•Urine is a suitable wastewater for high rate hydrogen production in an MEC.•Ammonium recovery is possible, but requires enhancement in the design and operation.•High COD and ammonium removal rates are achieved in an MEC.•MECs allow for higher ammonium recovery rates compared to MFC.

We investigated the use of a Microbial Electrolysis Cell (MEC) for the ammonium removal, COD removal and hydrogen production from five times diluted urine. During operation with a batch cathode, a current density of 23.07 ± 1.15 A m−2 was achieved corresponding to a hydrogen production rate of 48.6 ± 7.47 m3 H2 m−3 MEC d−1, an ammonium removal rate of 173.4 ± 18.1 g N m−2 d−1 and a COD removal rate of 171.0 ± 16.9 g COD m−2 d−1. Ammonia stripping was not possible in the applied MEC and ammonia diffusion from cathode to anode compartment led to a relatively short stable operation period. The stable operation period was prolonged by addition of new cathode media (HRT 6 h), but this resulted in a lower current density (14.64 ± 1.65 A m−2), hydrogen production rate (32.0 ± 0.89 m3 H2 m−3 MEC d−1), ammonium removal rate (162.18 ± 10.37 g N m−2 d−1) and COD removal rate (130.56 ± 4.45 g COD m−2 d−1).