The importance of the electron acceptor: Comparison between flooded and tidal bioelectrochemical systems for wastewater treatment and nutrients enriched solution production

In this study, a new bioelectrochemical system (BES) with an alternative setup of microbial fuel cell (MFC) is proposed: an additional cathodic collecting chamber is added to the air-exposed cathode to allow the recovery of the cations migrating from the anodic chamber. Up to 60 % of inorganic nutrients and 85 % of COD were removed from wastewater (WW). In the cathodic chamber, recovered nutrients partitioned differently depending on their solubility: P, Mg and Ca were predominantly found in precipitates as insoluble salts, while Na and K in the cathodic solution. N was recovered from the cathodic chamber as ammonia (NH3) (22 %) and as precipitate while deposited on the cathode as salts (15 %). Flooded versus tidal operation modes were further compared to achieve the best oxygen (strong electron acceptors) supply in the anodic chamber to increase biological COD degradation and nutrients migration towards the cathodic chamber.