Merging Microbial Electrochemical Systems with Conventional Reactor Designs for Treating Wastewater
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Escuela de Posgrado de la Universidad de Alcalá Programa de Doctorado en Hidrología y Gestión de Recursos Hídricos Merging Microbial Electrochemical Systems with Conventional Reactor Designs for Treating Wastewater Memoria presentada para optar al título de Doctor por la Universidad de Alcalá por : Sara Tejedor Sanz Dirigida por: Abraham Esteve Núñez Departamento de Química Analítica, Química Física e Ingeniería Química de la Universidad de Alcalá Alcalá de Henares, 2016 Cuando emprendas tu viaje hacia Itaca debes rogar que el viaje sea largo, rico en aventuras, lleno de conocimientos. No has de temer ni a los lestrigones ni a los cíclopes, ni la cólera del airado Poseidón. Nunca tales monstruos hallarás en tu ruta si tu pensamiento es elevado, si una exquisita emoción penetra en tu alma y en tu cuerpo. Los lestrigones y los cíclopes y el feroz Poseidón no podrán encontrarte si tú no los llevas ya dentro, en tu alma, si tu alma no los conjura ante ti. 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Index Summary……………………………….……………………………...………….……….. 11 Resumen………………………….………………………………………………...……... 15 CHAPTER 1: Introduction, Objectives And Research Framework Introduction………………………………………………………………………............. 21 1.1 Microbial Electrochemistry: Fundaments………………………………..……. 21 1.1.1 The Origins Of Microbial Extracellular Electron Transfer (EET)…….…. 21 1.1.2 How Do Microbes Perform Extracellular Electron Transfer?.................. 23 1.1.3 Geobacter As Model Bacteria In Microbial Electrochemistry…………… 25 1.2 Microbial Electrochemical Technologies: A Versatile Platform For Dd Environmental Applications………………………...………………….…......... 28 1.2.1 Classification Based On The Electrochemical Operation Mode……...… 29 1.2.2 Prototypes Of METs And Applications………………………...…............. 31 1.3 METs As A Novel Technology For Wastewater Treatment…………………. 37 1.3.1 Fundaments And Objectives……………………………...……………….. 39 1.3.2 Scaling Up METs In WWTP: State Of The Art…………………………... 43 1.3.3 Future Perspectives For The Bioelectrochemical Wastewater D Treatment…………………………………………………………………...... 47 J Objectives And Thesis Outline……………………………………………………....... 51 Research Framework…………………………………………………………...……….. 53 CHAPTER 2: The Planktonic Relationship Between Fluid-Like Electrodes And Bacteria: Wiring In Motion 2.1 Abstract……………………....…………………………………………………... 59 2.2 Introduction……………………...………………………………...…...……..…. 59 2.3 Materials And Method.……………...……………………………….………..… 61 Experimental Procedures………………………….……………………….. 63 2.4 Results And Discussion..……………………………………….….…..……….. 65 Discharging Of Plug-And-Play Geobacter Cells In The ME-FBR………. 65 Geobacter Growth Performing EET In The ME-FBR……………………. 67 Discharging Assays Of G. sulfurreducens After Open Circuit Periods... 70 5 Fe (III) Respiration Of Geobacter Planktonic Cells Grown In The ME- Kk k FBR……………...………………..………………...………………..…….… 89 2.5 Conclusions………………………...………………..…………………………... 74 2.6 Supplementary Information……………………....………………..….….......... 77 CHAPTER 3: Fluidized Bioanodes Versus Non-Conductive Classical Fluidized Beds On The Treatment Of A Brewery Effluent 3.1 Abstract………………………....……………….………………….…..........….. 83 3.2 Introduction………………………...…………….………………………............ 83 3.3 MaterialsAnd Method.……………...……………………………………………. 86 3.4 Results And Discussion..………………...……………………….….……...….. 89 Treating brewery wastewater: ME-FBR versus a Classical Fluidized Bed Reactor………………………………………………………………….. 89 Performance of the Systems Under a Fixed Bed Scenario………….….. 92 Influence of Organic Loading Rate on Reactor Performance…………... 92 Microbial Colonization of the Particles…………………………………….. 95 3.5 Conclusions………………………...……….…….……………..……...…..…… 93 3.6 Supplementary Information……………………...………………….……......... 95 CHAPTER 4: Complementary Technologies To ME-FBRs For Achieving A Complete Wastewater Treatment Part I: Integrating A Microbial Electrochemical System Into A Classical Wastewater Treatment Configuration For Removing Nitrogen From Low COD Effluents 4.1 Abstract………………………..……………………………………………......... 107 4.2 Introduction………………………...…………..……………………...…………. 107 4.3 Materials And Method.……………...…………………………………………... 109 Experimental Procedures…………………………………………………… 111 4.4 Results And Discussion..…………………………………………..……........... 113 Start-up of The System……………...……………………………………… 113 Assessment of Different COD/N Ratios in the Influent Under Continuous Mode……………...…………………………………………….. 114 Operation Of The System Without Internal Recirculation at COD/N=4... 117 Effect of the Electrodes Polarization of the Nitrogen Removal Process. 118 6 Sludge Production……………...……………………………………………. 120 Biofilm Characterization And Microbial Community Analysis…………… 120 4.5 Conclusions………………………....…………….…………………….…......... 124 4.6 Supplementary Information……………………...……………..………………. 127 Part II: Merging Microbial Electrochemical Systems With Electrocoagulation Pretreatment For Achieving A Complete Treatment Of Brewery Wastewater 4.7 Abstract……………………….…………………………….…….….…….......... 137 4.8 Introduction………………….…...…………………….…………….…..………. 137 4.9 Materials And Method.……………...…………………………………………... 138 4.10 Results And Discussion..………………………………………….….…..…….. 140 Electrocoagulation for Removing Solids and Nutrients………………….. 141 Microbial Electrochemical-Fluidized Bed Reactor for Removing Soluble COD……………...……………………………………….........…… 143 4.11 Conclusions………………………...……….…….…….………………...……... 145 CHAPTER 5: General Discussion, Conclusions And Future Work 5.1 General Discussion And Conclusions……………………...….……………… 149 5.2 Final Conclusions……………………...………….……………………..…........ 161 5.3 Recommendations And Future Work…………………….……………............ 162 References……………………...…………………….………………………..….……… 167 Annex………..…………….……………………………………………………………….. 189 List Of Figures……………………....……………………………..…………………….. 191 List Of Tables……………………....………………………………………................... 197 Abbreviations……...………………………………………………………….…..….….. 199 Agradecimientos……………………...….……………………………….……………… 203 93 7 8 Summary UMMARY S 9 10 Summary Summary Microbial electrochemistry or electromicrobiology has emerged as a new subdiscipline of the biotechnology based on the study of the interactions between microbial living cells and electrodes. The catalytic properties of these microorganisms are very versatile and a diversity of fields can benefit from these UMMARY systems known collectively as Microbial Electrochemical Technologies (METs). S These technologies have emerged as novel systems that fill well within the recently recognized water-energy nexus by reason of their attractive applications in wastewater treatment and water desalination. However, the implementation of METs in real-world applications depends upon the resolution of microbial, technological and economical challenges. To date, METs have been understood as devices in which the catalysis is located at the electrode interface due to the need of microbial attachment forming a biofilm. The need of optimizing this interaction is the main challenge of the field, and has been mainly focused on improving the reactor and electrodes design, in addition to achieving better extracellular electron transfers mechanisms. In this thesis, we have explored new scenarios and strategies for overcoming the technological bottlenecks of METs in the wastewater treatment applications. The work has been organized in 5 chapters, 3 of them being experimental. Chapter 1 constitutes an introductory section to the microbial electrochemistry field with a description concerning the state of the art of the applying METs to wastewater treatment. Fundamenetal studies of the microbe-electrode interaction and the catalytic process are essential for optimizing the performance of the bioelectrochemical systems. In this regard, Geobacter sulfurreducens is considered the model microorganism of choice performing direct extracellular electron transfer (DEET) in microbial electrochemistry and thus, is extensively used in proof-of-concept assays. This bacterium typically forms multi-layer biofilms on METs electrodes. However, Geobacter, in its natural habitat, is typically planktonic when respiring insoluble electron acceptors as iron oxides. The biofilm configuration limits the performance of the system due to the restriction of having the reaction occur at the electrode-biofilm interface. This presents problems associated with the activity of the cells within the biofilm. In Chapter 2, we have designed a microbial electrochemical fluidized bed reactor (ME-FBR) with the aim of maximizing the superficial area of anode being 11 Summary available for electroactive microorganisms, and of improving the kinetics of the