Circumneutral microbial Fenton catalysis: Harnessing iron-redox synergy for sustainable pharmaceutical degradation.

The persistence of pharmaceutical contaminants like ketoprofen (KET) in aquatic environments poses escalating ecological and health risks, yet conventional Fenton processes remain constrained by acidic pH dependency and unsustainable chemical inputs. Here, we present a nature-inspired, self-sustaining micro-Fenton (MFenton) system that harnesses indigenous facultative anaerobic iron-reducing microbial consortia to achieve > 80 % KET degradation under circumneutral pH without exogenous reagents. Unlike single-strain bio-Fenton models, this community-driven strategy leverages synergistic iron-redox cycling where DIRB (Dissimilatory Iron-Reducing Bacteria) biogenically generate Fe(II) and H2O2 through alternating anaerobic-aerobic phases, enabling in-situ hydroxyl radical (HO˙) production at pH 7.0. Decoding microbial black-box interactions, we identify Sporanaerobacter, Sedimentibacter, Clostridium, Petrimonas, and Actinomyces as keystone genera orchestrating Fe2+/H2O2 dynamics, while UPLC-ESI-HRMS analyses reveal KET degradation pathways dominated by side-chain decarboxylation (yielding 3-ethylbenzophenone) and ketone CC cleavage (forming benzoic acid). Crucially, this system eliminates pH adjustment needs and reduces energy demand compared to conventional Fenton methods, offering a scalable prototype for low-carbon pharmaceutical wastewater remediation. Our findings redefine the boundaries of microbially-driven advanced oxidation, providing mechanistic insights into how natural iron-redox networks can be engineered for contaminant elimination in dynamic environments.