Bio‐electro‐Fenton systems for sustainable wastewater treatment: mechanisms, novel configurations, recent advances, LCA and challenges. An updated review

Abstract

Bio‐electro‐Fenton processes use biological electrons produced from bioelectrochemical systems to treat wastewater. The most significant advantages of bio‐electro‐Fenton systems are high effectiveness, low toxicity, gentle operation conditions, environmentally friendly treatment without sludge accumulation and energy conservation. Though promising, bio‐electro‐Fenton systems still face several challenges, such as high power density, H2O2 concentration, cathode materials, Fe2+ concentration and pH. This review comprehensively discusses the mechanisms of bio‐electro‐Fenton systems. Then, structural configurations are critically reviewed, including microbial fuel cells coupled with electro‐Fenton systems, microbial electrolysis cells coupled with electro‐Fenton systems and other bioelectrochemical systems coupled with electro‐Fenton systems. Furthermore, recent advances in bio‐electro‐Fenton systems for wastewater treatment are introduced, including dye solution, pharmaceuticals and personal care products, oily wastewater, landfill leachate and other pollutants. In addition, the current challenges and specific future prospects of bio‐electro‐Fenton, such as possible mechanisms for improving the power output, electrode materials that are potentially useful, self‐designed electrodes and methods of maintaining circumneutral pH values, are also explored. Heretofore, great progress in bio‐electro‐Fenton has been made, but further improvements are still needed in order to make this system more economical and practical. © 2020 Society of Chemical Industry

Degradation of dexamethasone in water using BDD anodic oxidation and persulfate: reaction kinetics and pathways

“…This new approach to the treatment of resistant pollutants is attractive because it depends on producing free radicals, which are capable of oxidizing a wide range of pollutants to mostly harmless compounds, or complete mineralization to CO 2 , H 2 O and inorganic ions 11,12 . Electrochemical oxidation has been a promising technology for the degradation of micropollutants since the development of boron‐doped diamond (BDD) as anodic material 13 .…”

A novel bio-electro-Fenton system with dual application for the catalytic degradation of tetracycline antibiotic in wastewater and bioelectricity generation

“…59,83 Generally, in the BEF system, in situ electrogenerated H 2 O 2 as a strong oxidant is the most important factor because H 2 O 2 is considered as a major source of cOH production in Fenton oxidation. 56 Therefore, this alternative approach, due to its high efficiency in the generation of Fenton reagent (e.g., H 2 O 2 ) and the saving costs related to the storage and transport of chemicals, is advantageous in comparison to the other AOP processes, such as conventional Fenton process, 84 UV/H 2 O 2 , 85 photocatalysis, 45,46 etc., in which H 2 O 2 needs to be added. 15 For example, Naushad et al 86 investigated the photo-degradation of methylene blue dye by applying different concentrations of H 2 O 2 .…”

“…55 The results of previous studies showed that Shewanella, Geobacter, Arcobacter, Comamonas, Dechloromonas, Sphingobacterium, Desulfobulbaceae, Firmicutes, and Clostridium were wellknown and dominant electrochemically active bacterial species in mixed culture biolm that attach to the anodic electrode and form a dense biolm layer. 50,56,120…”

“…53,54 In BEF systems, biomass as an organic substrate is oxidized by electrochemically active bacteria through bioelectrochemical reactions in the anaerobic anodic chamber, so no external electricity supply is required as opposed to the EF process. 50,55,56 Then, the produced bio-electrons and protons from the microbial metabolism in the oxidation of biologically degradable substrate are transferred simultaneously to the cathodic compartment via the external circuit and proton exchange membrane, respectively. 52,57,58 H 2 O 2 is also formed through the two-electron reduction of electron acceptors (O 2 ) (eqn (1)) in the cathodic chamber, which reacts with the iron catalyst to generate cOH through eqn (2) and the EF oxidation occurs.…”

Austenitic Stainless Steel as a Catalyst Material for Photo-Fenton Degradation of Organic Dyes

“…Zero-valent iron is a strong reducing agent and has been used in particulate form for the removal of different organic (aromatic compounds) for groundwater remediation in the form of permeable reaction barriers [9] or as a slurry [10]. ZVI in the form of micropowders with diameters in the range of 50 to 200 µm [11] or in the form of nanopowders [12] shows a good reactivity in the presence of H 2 O 2 , meaning it could react with the surface iron to produce Fe 2+ and Fe 3+ and initiate the Fenton process [13][14][15]. Several studies have demonstrated that the optimal pH in the case of ZVI shifts to higher values (4 to 6), allowing outstanding degradation efficiencies for organic aromatic compounds [16,17].…”