FIGURE 6.

A schematic representation of the combination of partial-nitritation/anammox (PN/A) and N-dAOM processes in WWT. (A) Canonical denitrification where space, energy, and organic carbon, are needed for complete nitrogen removal in WWT. Denitrification produces sludge and GHG emissions as by-products under unfavorable conditions. (B) Partial-nitritation/anammox process, as a short cut to complete denitrification. AOB (in yellow) oxidize ammonia to nitrite, anammox bacteria (in red) oxidize ammonia anaerobically using nitrite as electron acceptor. (C) Incorporation of N-dAOM processes to PN/A, where both achieve the simultaneous removal of ammonia and methane (represented in green and blue for nitrate- and nitrite-dAOM, respectively). Broken arrows indicate competing processes that are deemed undesirable or processes that are circumvented by the implementation of the PN/A and N-dAOM processes. Adapted from Guerrero-Cruz (2018).