Industrially scalable surface treatments to enhance the current density output from graphite bioanodes fueled by real domestic wastewater

•Electromodified graphite promoted the ESEA and fixation of bacteria•Surface electromodification increased mostly surface nanotopography capacitance•Bioanodes fed only with domestic wastewater continuously supplied 2.8 A/m2•The predominance bacteria did not differ despite modification Acid electrochemical treatments electrode, used individually or in combination, significantly improved microbial anode current production, by +17% to +56%, well-regulated duplicated electroanalytical experimental systems.Of all consequences induced treatments, modifications nano-topography preferentially justify an improvement bacteria, increase specific area electrochemically accessible electrodes, which are at origin higher performances bioanodes wastewater. The evolution chemical composition appearance C-O, C=O, O=C-O groups on created combining acid was prejudicial formation efficient domestic-wastewater-oxidizing bioanodes. comparative discussion, focused positioning performances, shows industrial interest applying treatment method world bioelectrochemical systems. Of Bio-electrochemical technologies such as electrolysis cells (MECs) fuel (MFCs) promising processes for energy recovery (Zhu et al., 2011Zhu N. Chen X. Zhang T. Wu P. Li J. Improved performance membrane free single-chamber air-cathode nitric ethylenediamine modified activated carbon fiber felt anodes.Bioresour. Technol. 2011; 102: 422-426Crossref PubMed Scopus (167) Google Scholar). However, deployment these is (generally) limited low oxidation kinetics bioanode, especially when low-COD (chemical oxygen demand) effluents (dWW) treated (Liu 2014Liu W. Cheng S. Guo Anode formic acid: a simple effective improve power generation cells.Appl. Surf. Sci. 2014; 320: 281-286Crossref (23) Among possible ways boosting anodic reaction process, one option densities generated bioanode materials (Li Cheng, 2019Li C. Functional group enhancing exoelectrogenic biofilms system.Crit. Rev. Biotechnol. 2019; 39: 1015-1030Crossref (12) Scholar; Mohamed 2018Mohamed H.O. Sayed E.T. Cho H. Park M. Obaid Kim H.-Y. Barakat N.A.M. Effective strategies harvesting using cells.J. Environ. Manage. 2018; 206: 228-235Crossref (16) Electrode modify several aspects bioanodic Scholar), improving extracellular electron transfer (EET), increasing anode, promoting adhesion that initiate electroactive biofilms, example. Surface electrode can be achieved chemical, electrochemical, mechanical, thermal, pressure, vacuum combination methods. A distinction made between methods exogenous added (coating, grafting, painting, etc.) those do involve any additional material (passivation, polishing, machining, etc.). Using electrodes new approach development Table 1 summarizes major that, applied carbon-based materials, have All cited included this literature review, particular attention being paid features necessary make them widely available scale, i.e., simplicity implementation, cost, rapidity execution, possibility benefiting from existing industries. In fine, significant gains, ranging 20% 256%, been reported depending pre-treatment (Fiset Puig, 2015Fiset E. Puig Modified electrodes: systems.J. Bioremed. Biodegrad. 2015; 6: 1000e161Google Scholar).Table 1Effect density bioanodesType treatmentAnodic materialEffect surfaceUntreated densityTreated densityCurrent improvementReferenceAcid bath (nitric acid)Activated fibersIncreases number N functional surface, improves bacterial adhesion6 A/m29.5 A/m258%(Zhu Scholar)Acid (formic acid)Carbon clothDecreases O increases EET rate3.6 A/m24.8 A/m233%(Liu Scholar)Doping (Ag nanoparticles)Graphite plateIncreases rate1,100 A/m31,400 A/m327%(Sadri 2017Sadri F. Khodavandi A. Shamsazar Negahdary Rahimi G. Nano-biological cell.Fresenius Bull. 2017; 26: 4561-4567Google (Ca-S particles)Activated granulesImproves adhesion23.1 A/m340.1 A/m374%(Yasri Nakhla, 2017Yasri N.G. Nakhla 3-D doped anodes Power Sourc. 342: 579-588Crossref (18) Scholar)Electrochemical (applied voltage)Graphite porosity capacitance1.6 A/m22.6 A/m263%(Tang 2015Tang Yuan Y. Cai Zhou situ graphene layers surfaces cells.Biosens. Bioelectron. 71: 387-395Crossref (78) potential)Carbon feltCreates micro-cavities adhesion450 mA/m21,600 mA/m2256%(Cercado-Quezada 2011Cercado-Quezada B. Delia M.-L. Bergel Electrochemical micro-structuring accelerated anodes.Electrochem. Commun. 13: 440-443Crossref (44) current) + sulfuric acids)Carbon clothIncreases decreases resistance EET, adhesion153 ?A/cm2183 ?A/cm220%(Li 2014Li Baitao Wang Baikun Santoro Grattieri Babanova Artyushkova K. Atanassov Schuler A.J. anodes: approaches practical design.Electrochim. Acta. 134: 116-126Crossref (62) Scholar)Mechanical (roughened surface)Graphite area33 A/m343 A/m330%(Ebrahimi 2017Ebrahimi Kebria D.Y. Darzi G.N. Enhancing biodegradation via roughened desalination cell.Water 76: 1206-1214Crossref (17) Scholar)HydrothermalGraphite wettability, rate520 mA/m2990 mA/m290%(Liu 2017Liu Liu Feng Z. Jia Gong L. Xu Enhanced cell microspheres anode.Energy Eng. 5: 217-225Crossref Scholar) Open table tab among simplest treatment, their technologically easy achieve. addition, through experiments MFCs, Scholar already validated advantages coupling pre-treatments cloth anodes. start-up MFCs integrating due stronger faster biomass. Above all, long-term (by 20%) compared based untreated commercial This pioneering work highlights effect modifying chemistry has electrical material, (EASA), and, finally, fixation. questions persist concerning type interactions electrolytes carrying soluble molecules, colloids (macromolecules), particles, various other cells. It now well known broad field (Carniello 2018Carniello V. Peterson B.W. van der Mei H.C. Busscher H.J. Physico-chemistry initial surface-programmed biofilm growth.Adv. Colloid Interf. 261: 1-14Crossref (98) 2018Wu Suo Influence topography adhesion: review.Biointerphases. 060801Crossref (50) more specifically (Champigneux 2018bChampigneux Renault-Sentenac Bourrier D. Rossi M.L. Effect nano/micro-structuring early Geobacter sulfurreducens: theoretical approaches.Bioelectrochemistry. 121: 191-200Crossref (20) solid play essential roles stages (detection, adsorption, adhesion, anchoring). therefore logical infer forming whose scales terms morphology may different singular electrocatalytic properties. present study, we understanding individual combined effects anodization (Cercado-Quezada flat they generate regarding microorganism-material properties biofilm-material interfaces. protocols were first evaluated standpoints changes (roughness [Pocaznoi 2012aPocaznoi Calmet Etcheverry Erable Stainless steel cells.Energy 2012; 9645Crossref (130) Scholar], [Roberts Slade, 2010Roberts Slade R.C.T. capacitance asymmetric carbon/?-MnO2 supercapacitors.Electrochimica 2010; 55: 7460-7469Crossref (81) Scholar]), elemental (X-ray photoelectron spectroscopy [XPS]), reactivity (material capacitance, active surface). Then compared, under conditions (electrode potential concentration maintained constant values [Rimboud 2014Rimboud Pocaznoi Electroanalysis systems: basics, progress perspectives.Phys. Chem. 16: 16349-16366Google Roubaud 2019Roubaud Lacroix R. Da Silva Basséguy Benchmarking synthetic grades, felt, cost-efficient cells.Front. Energy Res. 7: 1-12Crossref (5) ability act dWW-fueled produced control (i.e., electrodes). Finally, biodiversity communities established both determined molecular inventory species (Lu 2012Lu Xing Ren Pyrosequencing reveals highly diverse involved enhanced H 2 production waste sludge.Water 46: 2425-2434Crossref (270) Mateo 2018Mateo Cañizares Rodrigo M.A. Fernandez-Morales F.J. Biofilm planktonic population distribution. Key carbonaceous 93: 3436-3443Crossref After had performed plain following (A), (E), E protocols, imaged scanning microscopy (SEM) detect main topographic microscale changes, roughness, sharpness, deposits, damage surface. SEM images clearly showed substantial underwent (without treatment) (Figure 1). detail, result very sharply cracked layers, reminiscent obtained Tang Scholar, also plate, exfoliation direct +10 V plate 5, 15, 40 min (Tang presence extended double layer graphite, leading formed engineered material. application alone seemed slightly; simply became little irregular. Two roughness parameters then quantified optical microscopy: Sa, arithmetic mean Sku, measures sharpness Sku 2018aChampigneux Impact micro- nano-scale electrodes.Biosens. 118: 231-246Crossref (26) Sa measurements raw acid, given 2. 18% electrode. Surprisingly, decreased 8% A, whereas interpretation image rather suggested rougher. 70% after 65% respect These visible but still interpretable electrode.Table 2Surface (A, E, E) non-treated (control) electrodesGraphite electrodeA EAEControlSurface parametersSa (?m)2.9 ± 0.12.3 0.12.9 0.12.5 0.3Sku6 17 16 120 3A, acid; electrochemical. Parameters represented standard deviation 10 test data determination areas classical Brunauer-Emmett-Teller (BET) gas adsorption qualitative (Table 3). measured BET 2.7 m2/g 2.1 respectively, A-treated below measurement limit quantifiable Belsorp-Max system equipment.Table 3Electrochemically EAEControlSpecific (m2/g)2.7<12.1<1EASA (cm2)214341714A, electrochemical; EASA, area.<1: less than quantitative analytical method. area. <1: To understand greater detail evaluate operating conditions, cyclic voltammetry (CV) dWW electrolyte solution previously 4-cm2 non-colonized 2). Compared (Control), subjected and/or presented voltammograms rectangular shape characteristic capacitive behavior. exhibited high resistive properties, indicated inclination curve I/E abscissa axis. graphical representation actually appeared follow Ohm's law relationship, average almost directly proportional potential. calculated equation:JC=Jox?Jred2=v.Cwhere JC corresponds half-width pseudo-rectangular part voltammogram, Jox Jred currents during CV plotting reduction directions, respectively; v scan rate (V/s); C (F). values, whole range explored, 632 mF, 504 100 12 mF showing capacity collect stock charges layer. If it assumed graphite; area, equation Scholar):EASA=CCsp=JCv.1Cspwhere Csp (F/m2). Thus calculation EASA predicated prior (Csp) Assuming 4 cm2, 29.5 F/m2. 3. With multiplied 54 43 8 treatment. last case (A treatment), enough accurately, quantitatively results quantification appear relatively consistent each support our argument consequence treatments. XPS analysis 4) slight electrodes. percentage ranged 13.0% 15.0% 16.0% respectively. More rose 25.7%, 0.5% 2.6%. phenomenon occurring observed groups. same linked pH performed: medium (pH ?0.6) H2SO4/HNO3 instead mild (phosphate electrolyte) acidic easily O2 pH-neutral conditions. could groups.Table 4XPS (control)ElectrodeA EAEControlC68.580.981.383.6O25.715.016.013.0N2.60.50.60.5S3.03.11.72.7P0.20.50.40.2C-C; C-H; C=C47.371.871.374.6C-O; C-N13.46.05.77.1C=O2.51.40.80.6O=C-O5.31.73.51.3First five lines: atomic % element, four distribution content. First Microbial ?0.1 V/SCE system) strict comparison detailed (Roubaud successive runs two batches sludge (AS) duplicate results. batch AS reactors run, where run Monitoring exchange over 25 days gave curves shown Figure S1. steady-state (simply noted “current densities” rest text) averaged recorded chronoamperometry (CA) reactor 5. resulted delivering 17% 56% higher. series 20%–35% lower second experiments, no link difference caused inoculum temperature, thermostatically controlled experiments.Table 5Steady state electrodesElectrodeA EAEControlRun (A/m2)1.7 0.51.7 0.32.2 0.61.6 0.5Run (A/m2)2.4 0.42.5 0.43.4 0.62.0 0.2Average (A/m2)2.12.12.81.8Current improvement+17%+17%+56%NASteady averaging day stability (10th day) end experiment (25th day). Steady polarization V/SCE, turn-over CVs containing 360 mg COD/L experimentally allow Jmax reached without dependence organic matter