Removal of Organic Micropollutants from Municipal Wastewater by Aerobic Granular Sludge and Conventional Activated Sludge

Biotransformation of micropollutants in moving bed biofilm reactors under heterotrophic and autotrophic conditions

“…The two other compounds (NPX and DCF) have moderate average removal efficiencies of around 35.6-70.3% and 15.8-36.8%, respectively. Such differences suggest a compound-specific pattern of the MPs biotransformation in the MBBR system, which is consistent with the observations in other treatment systems like CAS, MBR and AGS (e.g., [12] and [35]). In these recent studies, DCF removal percentage of approximately 12.5% and 25% was reported in CAS and AGS systems, respectively, but values as low as 20% or even negative removal percentage was observed for CBZ.…”

“…This is particularly pronounced for NPX and DCF that had a larger removal percentage (i.e., more than twice for DCF) under dominant heterotrophic conditions in phase II (with higher biomass concentration) compared to the subsequent phases III and IV where the reactor was operated under fully autotrophic conditions. Except for CBZ which is a well-known recalcitrant compound [12,35], the MPs were degraded with varying degrees under autotrophic conditions in phase III and IV and are in the range of the previously reported studies [18,36]. The outcomes also indicate that increasing the COD/N ratio and thus the organic load in phase II led to a noticeable rise in the removal efficiencies of NPX and DCF, but did not have a significant impact on the IBP and CBZ degradation in the reactor.…”

“…The latter can be associated with production of more toxic by-products and needs to be accompanied by further post-treatment processes [9][10][11]. In order to minimize the use of such processes, the feasibility of emerging biological technologies like biofilm-based systems for enhanced degradation of MPs in WWTPs has been recently explored [12][13][14]. One notable example is moving bed biofilm reactors (MBBRs) that have been shown as a promising option for enhanced biodegradation and elimination of recalcitrant MPs (e.g., Diclofenac) in comparison to CAS systems [14][15][16][17].…”