The purpose of this study is evaluating a new water treatment technology; electrochemical technique and see if the technique is an alternative for municipal wastewater treatment. The aim of the project was also to test the electroflotation by purification of phosphorus from synthetic wastewater and separation of green algae from the culture medium so the technology can be evaluated. To answer the purpose, two different experiments were made at laboratory. In the first experiment, wastewater was purified from phosphorus with electroflotation. In the second experiment, green algae were separated with the same technology, but with different machine. The results of the study show that the electrochemical technology is a good technique to separate green algae from the culture medium. In the tests the removal efficiency was over 90 %. Results from the phosphorus purification did not go so well, because sources of error in the system. To summarize the results of the project the electrochemical technology is a good alternative to other wastewater treatments because it’s more environmental friendly and easy to operate.

Hexachlorobenzene (HCB) is a pollutant, and there is an urgent need to degrade it. Two methods of degrading HCB to ethers are nucleophilic substitution and electroreduction, chosen for their viability and safety. The kinetics of substitution of HCB by potassium hydroxide and methanol were examined. The substitution of HCB by methoxide produced 1,2,3,5-tetrachloro-4.6-dimethoxybenzene (1,2,3,5-TCDMB) as the major substitution product, and side reactions produced extra chloride due to other substitution products. Thus, the proposed reaction mechanism is complicated due to the formation of ethers and phenols due to consecutive and parallel reactions. The substitution products of HCB were uncatalytically and catalytically electroreduced. Products with increasingly more methoxy substituents had lower electron affinities and increasing positive free energies. Catalysed electroreduction was more effective than uncatalysed electroreduction in dechlorinating the HCB substitution products to aromatic ethers. The most effective organic catalysts were those that possessed the lowest electron affinity as reflected in the reduction potential. A combination of nucleophilic substitution and electroreduction of HCB and its substitution products produced mono-, di- and trimethoxide chloroaromatic ethers and phenols. These products, particularly the ethers, may have future applications as fragrance ingredients / Doctor of Philosophy (PhD)

Anaerobic digestion (AD) is a widespread technology for treating waste streams such as livestock manure. During AD, biogas is produced and subsequently used as renewable energy for certain purposes, such as injection into the natural gas grid or as fuel for transportation. Despite its many advantages, AD can be limited by various factors, including process instability against volatile fatty acids (VFA), nitrogen overloads, or the presence of inhibitors, as well as the need for biogas post-processing to increase its methane content. Therefore, strategies are needed to monitor the AD process, control the effluent quality and upgrade the biogas recovered. Microbial electrochemical technologies (MET) have the potential to optimize AD. MET are systems in which oxidation and/or reduction reactions are catalyzed by electroactive microorganisms (EAM) on the surface of an electrode. Typically, EAM used in AD-MET combinations are dominated by Geobacter spp., that form multilayer biofilms on electrodes (e.g., anodes) used as solid terminal electron acceptors. However, using Geobacter spp. dominated biofilm anodes in AD-MET combinations has so far encountered several hurdles, ranging from biofilm dispersal to inhibition of biofilm performance. Thus, the intention of the present thesis was to identify and to address the different inhibition processes of Geobacter spp. dominated biofilm anodes in AD-MET combinations. Particular attention was devoted to the impact that planktonic methanogens, particles and dissolved components present in AD effluents may have on the activity, stability and microbial community of Geobacter spp. dominated biofilm anodes. This was achieved by investigating the effect of biofilm age, applied anode potentials as well as the role played by specific methanogens with different metabolisms on the activity, stability and microbial community of Geobacter spp. dominated biofilms. The results indicated that older Geobacter spp. dominated biofilm anodes (≥ 5-week-old) are far more active and stable than younger biofilms (≤ 3-week-old) in AD environments. Compared to high applied anode potential (0.4 V vs. Ag/AgCl sat. KCl), low applied anode potentials (-0.2 V to 0.2 V vs. Ag/AgCl sat. KCl) resulted in higher activities of Geobacter spp. dominated biofilm anodes in AD environments. Other results indicated that AD effluents dominated by strict acetoclastic methanogens (e.g., Methanothrix spp.) cause deterioration in biofilm stability and activity, in contrast to AD effluents dominated by hydrogenotrophic methanogens (e.g., Methanobacterium spp.). In conclusion, the thesis provides useful information for understanding and improving the performance of AD-MET combinations and ways to overcome the multiple hurdles encountered so far.:1 Introduction 12 1.1 Basics of microbiology of anaerobic digestion 12 1.1.1 Methanogens and their functionality 12 1.1.2 Anaerobic digestion - methanogens and bacteria 13 1.1.3 Microbial diversity in anaerobic digestion: focus on methanogens 14 1.1.4 Metabolism and syntrophy in anaerobic digestion 16 1.1.5 Parameters influencing anaerobic digestion 18 1.2 Microbial electrochemical technologies 19 1.2.1 Primary microbial electrochemical technologies - possible applications 19 1.2.2 Basic examples of primary microbial electrochemical technologies 21 1.2.3 Geobacter spp. as model electroactive microorganism in microbial electrochemical technologies 23 1.2.4 Modes of electron transfer between electroactive microorganisms and electrodes 24 1.2.5 Electrochemical characterization of biofilm anodes 27 1.3 Combination of anaerobic digestion and microbial electrochemical technologies 28 1.3.1 Benefits: biotechnological applications 28 1.3.2 Challenges: factors limiting the combination anaerobic digestion - microbial electrochemical technologies 29 1.4 Aims and thesis outline 30 2 Publication 1: Benefits of Age – Improved Resistance of Mature Electroactive Biofilm Anodes in Anaerobic Digestion 33 2.1 Supplementary information for “Benefits of Age – Improved Resistance of Mature Electroactive Biofilm Anodes in Anaerobic Digestion” 43 3 Publication 2: Combining Geobacter spp. dominated biofilms and anaerobic digestion effluents - the effect of effluent composition and electrode potential on biofilm activity and stability 55 3.1 Supplementary information for “Combining Geobacter spp. dominated biofilms and anaerobic digestion effluents - the effect of effluent composition and electrode potential on biofilm activity and stability” 67 4 Publication 3: A unified and simple medium for growing model methanogens 91 4.1 Supplementary information for “A unified and simple medium for growing model methanogens” 105 5 Publication 4: Effect of model methanogens on the activity, stability, and microbial community structure of Geobacter spp. dominated biofilm anodes 117 5.1 Supplementary information for “Effect of model methanogens on the activity, stability, and microbial community structure of Geobacter spp. dominated biofilm anodes” 153 6 Discussion 167 6.1 The older the biofilm, the higher its activity and resistance when combined with anaerobic digestion effluents 167 6.2 Low applied anode potential leads to high activity of Geobacter spp. dominated biofilm in anaerobic digestion environments. 168 6.3 The role of methanogens, abiotic particles, dissolved components in the combination anaerobic digestion – microbial electrochemical technologies 170 6.3.1 Abiotic particles, dissolved components present in anaerobic digestion effluents do not always interfere with the activity, stability and community of Geobacter spp. dominated biofilm anodes 170 6.3.2 The activity and community of Geobacter spp. dominated biofilm anodes in anaerobic digestion environments vary with the predominant group of methanogens 171 7 Conclusions and future prospects 173 8 References 176 9 Appendix 187 9.1 Author contribution statements of published articles 187 9.2 Curriculum vitae 193 9.3 List of publications and conference contributions 196 9.4 Acknowledgment 199 9.5 Declaration of authorship 201

Microbial resource mining of electroactive microorganism (EAM) is currently methodically hampered due to unavailable electrochemical screening tools. Here, we introduce an electrochemical microwell plate (ec-MP) composed of a 96 electrochemical deepwell plate and a recently developed 96-channel multipotentiostat. Using the ec-MP we investigated the electrochemical and metabolic properties of the EAM models Shewanella oneidensis and Geobacter sulfurreducens with acetate and lactate as electron donor combined with an individual genetic analysis of each well. Electrochemical cultivation of pure cultures achieved maximumcurrent densities (jmax) and coulombic efficiencies (CE) that were well in line with literature data. The co-cultivation of S. oneidensis and G. sulfurreducens led to an increased current density of jmax of 88.57 ± 14.04 μA cm−2 (lactate) and jmax of 99.36 ± 19.12 μA cm−2 (lactate and acetate). Further, a decreased time period of reaching jmax and biphasic current production was revealed and the microbial electrochemical performance could be linked to the shift in the relative abundance.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-08-28T16:30:59Z No. of bitstreams: 1 ILZA MARIA DO NASCIMENTO BRASILEIRO - TESE PPGEP 2006..pdf: 2336923 bytes, checksum: 7428c7728ba45c4c9d6d5bc534fc602b (MD5) / Made available in DSpace on 2018-08-28T16:30:59Z (GMT). No. of bitstreams: 1 ILZA MARIA DO NASCIMENTO BRASILEIRO - TESE PPGEP 2006..pdf: 2336923 bytes, checksum: 7428c7728ba45c4c9d6d5bc534fc602b (MD5) Previous issue date: 2006-07-07 / A presença de água associada ao petróleo provoca uma série de problemas nas etapas de produção, transporte e refino. Na produção e transporte os maiores inconvenientes está ligada à necessidade de superdimensionamento das instalações de coleta, armazenamento e transferência, incluindo bombas, linhas de tubulações, tanques, etc, além do maior consumo de energia e segurança operacional. Em virtude de sua composição (material em suspensão, microrganismos, sais e gases dissolvidos) a água de produção pode sofrer variações de temperatura e pressão, provocar problemas de corrosão e/ou incrustação, causando danos às tubulações, equipamentos e acessórios (válvulas, instrumentos, etc.), podendo redundar em acidentes humanos e/ou ambientais. No processo de extração e refinação do petróleo, por exemplo, o efluente gerado apresenta concentrações elevadas de sulfetos, N-amoniacal, fenóis, óleos e graxas. Todos estes são compostos altamente nocivos ao meio ambiente e necessitam de tratamento antes do descarte para se enquadrarem às normas ambientais e com isso não causar danos ao meio ambiente. Os processos eletroquímicos possuem um grande potencial no tratamento de efluentes devido ao reduzido tempo de tratamento, pequena área de instalação quando comparada aos processos convencionais, além da possibilidade de serem associadas a outros processos no pré ou pós-tratamento de efluentes e não exigem, de maneira geral, insumos químicos. O principal objetivo de este trabalho é à aplicação da tecnologia eletroquímica na oxidação de poluentes advindos do processo de produção/refino da indústria de petróleo, para este propósito foi estudado e desenvolvido um reator que possa funcionar com eficiência no processo de eletroxidação. Além disto, o trabalho aborda o estudo da incrustação nos eletrodos, a mesma que causa diminuição considerável no rendimento do processo. O reator utilizado em este estudo foi um reator eletro número total de experimentos e consequentemente diminuir os custos operacionais do estudo em questão. Foram analisados os seguintes parâmetros dependentes: salinidade (mg/L), potencial elétrico (V), vazão volumétrica (l/h) e intervalo de eletrólise (h). Como indicadores da eficiência do tratamento eletroquímico foram analisados os seguintes parâmetros independentes: percentual de remoção de sulfeto, N-amoniacal, fenol e índice de incrustação relativo. Após a análise de todos os resultados feitos com o efluente sintético, puderam-se estabelecer as condições limites para os parâmetros (dependentes) a serem estudados no processamento com o efluente real do Pólo Industrial de Guamaré/RN e que apresentaram os melhores resultados. As melhores condições operacionais para as variáveis de entrada foram: vazão volumétrica de 380 l/h, potencial elétrico de 4 V e intervalo de eletrolise de 0,29 horas. O percentual de remoção de sulfeto foi avaliado na forma de perfil de concentração, e conforme o esperado, a remoção foi em torno de 100 %. A remoção do fenol foi em torno de 100 %, para o tempo total de eletrólise, que foi de 2 horas. Com a finalidade de avaliarmos o nível de incrustação nos eletrodos que também foi um dos objetivos de nossa pesquisa, foram realizadas análises físico-quimicas de alcalinidade e dureza em CaCO3, índice de incrustação por cronoamperometria e microscopia eletrônica de varredura dos eletrodos. / The presence of water associated to the oil provokes a series of problems in the production, transport and refining stages. In the transport and production stages the greatest inconvenient are the necessity of supersizing the collection of installations, storage and oil/water transfer. Here are included pumps, tubings, tanks, etc., beyond the biggest energy consumption and operational security. In virtue of its composition (suspended material, microorganism, salts and dissolved gases). The water production may suffer temperature and pressure variation, to provoke corrosion and/or incrustation problems, causing damages to the tubings, equipment and accessories (valves, instruments, etc.) being able to result in human and/or environmental damages. In the extraction and refinement of oil process, for example, the generated effluent presents high concentration of sulphide, N-ammoniacal, phenols, oil and greases. All these compounds are highly harmful to the environment and need treatment before the discharging in order to fit itself to environmental norms and did not cause damages to the environment. The electrochemical processes possess a great potential in effluents treatment due to the reduced time of treatment, small area of installation when compared to the conventional processes beyond the possibility to be associates to other processes such as before and posttreatment effluent, and they do not demand, in general way chemical reagents. The main objective of the present work is the application of the electrochemical technology in the oxidation of pollutants coming from the production/refining process of oil industry, for this purpose, was studied and developed an electrochemical reactor that can operate with efficiency in the electro-oxidation process. Moreover, the work approaches the study of the incrustation in the electrodes, which the same which causes the greatest decreasing in the electro-oxidation process efficiency. The reactor used in this study was following dependent parameters had been analyzed: salinity (mg/L), electric potential (V), volumetric flow rate (l/h) and electrolysis time (h). As efficiency indicators the following independent parameters had been analyzed: sulphide removal, N-ammoniacal and phenol percentage and relative index of incrustation. After analysis of all results mode with the synthetic effluent had been able to be established the conditions limits for the parameters (dependents) to be studied in the processing with the real effluent of the Industrial GuamaréPolo/RN and that they had presented the best results. The best operational conditions for the entrance variables had been: volumetric flow rate of 380 l/h, electric potential of 4 V and electrolysis time of 0,29 h. The sulphide removal percentage was evaluated in the form of concentration profile, and according to the expectation the removal was around 100 %. The phenol removal was around 100%, for the total electrolysis time that was of 2 hours. With this purpose of evaluating the incrustation level in the electrodes that also was one of the aims of our research, was carried out physical-chemistry analysis of alkalinity and hardness in CaCO3, incrustation index for chronoamperometric technique and scanning electronic microscopy of the electrodes.