Orientador: Jairo Osvaldo Cazetta / Banca: Miguel Angelo Mutton / Banca: Silvelena Vanzolini Segato / Resumo: Com o objetivo de estudar o comportamento do concentrado de vinhaça biodigerida (CVB) em relação à vinhaça in natura (VN), no crescimento e na nutrição de plantas de cana-de-açúcar, foi desenvolvido um experimento em vasos contendo a combinação de dois solos (latossolo e argissolo), com dois níveis de fertilidade (sem e com a correção da fertilidade) e com quatro tratamentos qualitativos em relação ao K (sem adição de K; com VN na dose de 100 m³ ha-1, com CVB ou KCl em dose de K igual à da VN). Os resultados revelaram que houve comportamento similar entre as vinhaças, tanto na ausência como na presença da correção da fertilidade do solo, sendo que para o concentrado de vinhaça biodigerida os valores tenderam a serem inferiores. O latossolo na ausência da correção da fertilidade induziu maiores resultados para crescimento e nutrição das plantas, em relação ao argissolo, por ter fertilidade original melhor. Porém na presença da correção da fertilidade o latossolo induziu menores resultados. A correção da fertilidade do solo é fundamental para se obter melhores respostas para o crescimento e nutrição da planta de cana-de-açucar, assim tanto o latossolo quanto o argissolo, bem manejados, podem proporcionar bons resultados / Abstract: In order to study the effect of concentrated of biodigested vinasse (CVB) compared to in natura vinasse (VN) on the growth and nutrition of sugar cane plants, an experiment was conducted in pots containing a combination of two soils (Oxisol and Ultisol) with two fertility levels (with and without fertility correction) and with four qualitative treatments related to K (control = without addition of K; with VN in a dose of 100 m³ ha-1; with CVB or KCl at a dose of K equal to the VN). The results showed that with soil fertility correction, the CVB had similar behavior regarding to plant height, stem diameter, internodes number, leaf area, K and Mg content, and accumulation of P. The VN promoted higher values for P content, and accumulation of Cu and K, N, Ca, S and Cu. In the absence of soil fertility correction, CVB was similar to overall plant growth and accumulation of K, N, Ca, S and Cu; the highest values for VN on K content and higher values for CVB regardong to Mg, P and Cucontent, and accumulation of P. In the Oxisol, both vinasses induced similar values for content of K, S, Cu and Mn, and accumulation of S, N, Ca, Mg, Mn and Zn. In the Ultisol vinasses had similar values for content of Mg, Cu and Mn, and Ca, Mg, Mn and Zn accumulation. The highest values of K and S levels, and S and N accumulation were found when plants were fertilized with VN. Both vinasses showed better results of K, Mg and Cu content in the Oxisol. The VN had similar behavior on both soils for S content, and induced higher values for Zn accumulation in Ultisol. The CVB induced higher values for S content and accumulation of Mg in both tested soils / Mestre

The Municipality of Quelimane, the fourth biggest city in Mozambique, aims to apply an EcoCity concept in the city. Therefore, the municipality initiated a waste-to-energy project in order to improve the lacking waste management, valorize resources and lessen the burden on the environment. The purpose of the current project was to investigate the potential for implementing a waste-to-energy system in Quelimane. In particular, the technology of anaerobic digestion. This technology had been identified as the best alternative based on local conditions according to a study performed by students at KTH, the municipality of Quelimane and GreenLight about waste-to-energy in Quelimane the spring of 2015. The present project was performed during eight weeks in Mozambique; five weeks in the capital Maputo and three weeks on-site in Quelimane, where the collection of data mainly was made in Quelimane. The gathered information resulted in a model for a small scale anaerobic digestion system in Quelimane. An assessment of the potential for an implementation of an anaerobic digestion system in Quelimane was determined using a feasibility assessment tool. The study was performed using the following methods: literature study, interviews, surveys, on-site observations, modelling and by using a feasibility assessment tool. The analysis performed with the feasibility tool identified the socio-cultural attitude towards the technology and the willingness among the residents to use the end products as key factors for a successful implementation. The attitude towards the technology was determined as mainly positive and the willingness to use the end product high. The strong involvement and initiative from the municipality were also identified as key factors and determined as positive. The environmental, policy and legal and the technological aspects of the system are other identified key factors were mainly identified as positive according to the feasibility assessment tool. However, there is currently no end user for the small scale plant and no established funding for the project. This altogether results in a current marginally high potential for the implementation of a small scale anaerobic digestion plant, with good chances to increase the potential in the future.

For enhancing anaerobic sludge digestion and biogas recovery, an increase in organic load rate (OLR) from 1.0 to 3.0kgVS/(m3·day) was imposed upon a new anaerobic digestion process combined with a sludge recirculation. The new setup requires a traditional mesophilic anaerobic digester coupled with a centrifuge for maintaining relatively high solid content within the digester. The hypothesis of this study was that increasing continuously OLR from 1.0 to 3.0kgVS/(m3·day) in a pilot-scale anaerobic digester with recycled sludge would not badly influence the digester stability, based on which biogas production would be enhanced. To test this hypothesis, a continuous 73-day study with laboratory experiment was conducted. Due to scarcity of original feeding sludge and its deteriorating quality, OLR had to be increased relied on introduction of extra sludge followed by measurement of total solid (TS) and volatile solid (VS) contents in both feeding sludge and digester sludge, for calculating OLR and examining its variations. To assess the relationship between biogas production and OLR, a measurement of gas yield and methane content was a necessity, performed by applying a biogas flow meter and MSA AUER EX-METER II (P). Moreover, temperature, pH value, volatile fatty acid (VFA) and alkalinity must be tested frequently, for the purpose of preventing system failure. The results demonstrate that the digester succeeded in withstanding an OLR up to 3.15kgVS/(m3·day). Furthermore, an enhancement in biogas yield and methane content were observed after increasing the OLR by introducing extra sludge. Biogas production measurement performed during this study indicated that biogas yield was enhanced by 73%, with a maximum production of 14.5m3/day, when OLR was increased from 2.05 to 3.15kgVS/(m3·day). However, methane content was merely promoted by 10.5%, to the highest value of 63%, with the same increase in OLR. Specific gas production (SGP), as another means of evaluating the relationship between biogas production and OLR, was observed to be 0.65Nm3/kg VSin averagely.

PhD (Department of Chemical Engineering, Faculty of Engineering and Technology), Vaal University of Technology / Anaerobic digestion (AD) is usually applied in the treatment of distillery effluent due to the fact that it is effective in chemical oxygen demand (COD) reduction and bioenergy recovery. However, due to the presence of biorecalcitrant melanoidins present in distillery effluent, AD is ineffective in colour reduction. For this reason, ultraviolet (UV) photodegradation, which is effective in melanoidins’ degradation, can be integrated with AD to achieve high efficiency in colour and COD reduction. However, the UV process is energy intensive, majorly due to the electricity requirement of the UV lamp. In contrast, the AD process has high potential of renewable energy production in the form of biomethane, which can be transformed into electrical energy and applied to supplement the energy requirement of the UV process. The aim of this study was to evaluate the efficiency of a combined AD-UV system in colour and COD reduction for the treatment of distillery effluent in fluidised bed reactors. The potential of the application of the bioenergy produced by the AD process to supplement the energy intensive UV process was evaluated and modelled using response surface methodology. In the first place, the optimal hydrodynamic conditions of the fluidised bed reactors were determined using optical attenuation technique. The best homogeneity in the bioreactor, in which zeolite was used as microbial support, was found to be at a superficial liquid velocity of 0.6 cm/s while the best catalyst and gas hold up in the photoreactor were found to be 0.077 and 0.003, respectively. At these conditions, it was found that the initial biological step removed about 90% of COD and only about 50% of the colour while photodegradation post-treatment removed 98% of the remaining colour. Kinetic analysis of the bioreactor showed that ~ 9% of the feed total organic carbon (TOC) was non-biodegradable and this was attributed to the biorecalcitrant melanoidins. Photodegradation post-treatment mineralized the biorecalcitrant melanoidins via a reductive pathway as was indicated by the formation of NH4+ in large quantity compared to NO3-. Kinetic analysis further showed that the rate of substrate utilization in the bioreactor increased with an increase in organic loading rate and it was inversely proportional to the rate of photodegradation post-treatment. Modeling using response surface methodology (RSM) was applied to predict the effects of the operating parameters of the initial AD step on the performance of the photodegradation post-treatment process and the energy efficiency. Energy analysis of the integrated system showed that the AD process could produce 59 kWh/m3 of electricity which could supplement the electricity demand of the UV lamp by 30% leading to operation cost reduction of about USD 4.8/m3. This led to a presumed carbon dioxide emission reduction (CER) of 28.8 kg CO2e/m3.

Thesis (Master of Environmental Management)--Cape Peninsula University of Technology, 2018. / Fresh water is a renewable resource, but it is also finite, especially given environmental impacts from anthropogenic activities. Globally, there are countless signs that untreated industrial discharge into fresh watercourses is one of the main causes of ecosystem degradation. Poultry slaughterhouse wastewater (PSW) amongst the main pollutants of fresh water sources. In recent years, the world’s pre-eminent researchers have developed innovative wastewater treatment processes to treat the large quantity of wastewater generated as well as to manage the environmental health concerns arising from PSW discharged into the environment. Furthermore, increasing wastewater treatment capital costs and the implementation of increasingly rigorous government legislation to mitigate environmental pollution whilst minimizing fresh water source contamination, requires that wastewater such as PSW, be adequately treated prior to discharge. In order to assist the small-scale poultry producers in South Africa (SA), process simulation for a small-scale poultry slaughterhouse wastewater treatment plant was proposed using Sumo Wastewater treatment plant (WWTP) simulation software. Sumo is an innovative and most versatile wastewater simulation package on the market. The simulator is capable of modelling treatment plants of unlimited complexity, focusing largely on Biochemical oxygen demand (BOD), Chemical oxygen demand (COD), nitrogen and phosphorus removal; with digester, and side streams design options, being available. Considering the possible advantages in modelling and ongoing studies of implementing wastewater treatment to increase water management, anaerobic digestion of high strength wastewater such as PSW, warranted this research study. Model development from the simulation included the evaluation of numerous design options to assist small scale poultry producers, to have a variety of designs to choose from in their PSW WWTP designs. With the aid of Sumo, two models were designed in this study, namely a single-stage and a two-stage anaerobic digestion without a recycle. The PSW used as feed was obtained from a local poultry slaughterhouse (Western Cape, South Africa). Both model designs predicted the reduction of the organic matter (COD, BOD5) total suspended solids (TSS), and volatile suspended solids (VSS) in the PSW. The digester for the single stage anaerobic digestion system modelled was set to operate at steady state for 150 days under mesophilic temperature (35 ˚C) with a solid retention time (SRT) of 25 days. The COD, TSS, VSS and BOD removal efficiencies reached a maximum of 64%, 77%, 84%, and 94%, respectively, at an organic load rate (OLR) of 143.6 mg COD/L/day. A minute increase in the ammonia (NH3) and phosphate (PO3- 4) concentration was observed once the simulation was completed. As for the two-stage anaerobic digestion system, both digesters were set to perform at mesophilic temperatures (35 ˚C) and a SRT of 13 days in the first digester and 25 days in the subsequent digester. The two-stage anaerobic digestion showed better performance in comparison to the single-stage anaerobic digestion system. The COD, TSS, VSS and BOD5 removal efficiencies reached a maximum of 69%, 79%, 85%, and 96%, respectively, at an at an OLR of 143.6 mg COD/L/day. A similar trend regarding phosphate and ammonia removal was noticed in the two-stage anaerobic digestion, suggesting a tertiary treatment system to be in place for further treatment. Although, the two-stage anaerobic digestion demonstrated adequate performance, for the purpose of this study, the single-stage was the process recommended for PSW treatment, as it is less costly and will be suitable for small scale poultry producers; albeit biogas production is much higher when digesters are connected in series. The PSW treatment modelling for this study was successfully employed with the resultant effluent being compliant with the City of Cape Town (CCT) wastewater and industrial effluent by-law discharge limits. Although, both the PO3- 4 and NH3 were suggested to require further monitoring. Therefore, the poultry slaughterhouse from which the PSW was obtained will be able to safely discharge the treated wastewater proposed in this research into local water bodies, i.e. rivers in the Western Cape, SA; however, the treated PSW will not be suitable for re-use as process water.

The organic wastes including olive oil mill residues are an inseparable part of food manufacturing processes while implying multi-faceted damages to the environment. A good quantity of research has been conducted to examine the biogas enhancement level in the anaerobic process of olive residues.  Seeking the optimum pretreatment method and the co-digesting substrates, the current study has conducted aggregative research on 155 experiments out of 22 studies. The conducted meta-analysis recognized the chemical type of pretreatments as the most effective treating procedures, according to which, application of the combined alkaline and lime, followed by trace metal cobalt supplementations are recognized as the most effective methods.  Furthermore, the study found intriguing results on the optimum type of olive main substrate, inoculum, digester type and effective volume as well as the superior country and year, in the anaerobic digestion of the olive mill residues.

No description available.

No description available.

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

[pt] Em um cenário onde a geração de resíduos ao redor do mundo cresce cada vez mais, técnicas de tratamento de resíduos são fundamentais para garantir menores emissões de gases de efeito estufa ao meio ambiente. Esta pesquisa apresenta uma análise realizada com cascas de dois tipos distintos de tangerina, com a finalidade de estudar o potencial de geração de biogás das mesmas através da realização de um ensaio BMP (Biochemical Methane Potential). A digestão anaeróbia de resíduos orgânicos corresponde a um tratamento biológico que apresenta uma solução com produtos valiosos, como o biogás, no combate ao aumento de emissões poluidoras, já que o mesmo pode ser utilizado como energia térmica, elétrica ou combustível em detrimento aos combustíveis fósseis. Dessa forma, esta pesquisa também realiza um estudo acerca do processo de fabricação de sucos naturais por parte de pequenos e grandes produtores e de como os mesmos podem utilizar as cascas dos restos da produção dos sucos para a geração de biogás como fonte de energia limpa. Os resultados encontrados apresentam para a casca da tangerina Ponkan um potencial de geração de biogás de 615,38 NmL/gSV e, para a casca da tangerina Montenegrina, o valor encontrado foi de 565,84 NmL/gSV. Os resultados obtidos sugerem um potencial de geração de biogás positivo para o substrato analisado, a tangerina, quando comparados aos demais resultados de outras frutas encontradas na literatura. / [en] The constant increase in global warming that occurred after the middle of the twentieth century and intensified by anthropogenic actions based on the emission of greenhouse gases such as methane, is a reality that worries not only for the harmful damages to the environment and the quality of life of human beings, but also for the preservation of future generations (Silva and Paula, 2009). In the mid-1980s, with the Brundtland conference, the concept for sustainable development emerged which is defined as meeting the needs of the present without compromising future generations (BRUNDLAND, 1987). In order to avoid excessive damage to the existence of human beings, recent studies by the Intergovernmental Panel on Climate Change (IPCC, 2018) examined the need to limit global warming to 1.5 Celsius instead of 2 Celsius, as previously predicted by the Paris Climate Agreement signed in 2015. According to the study, the absence of measures to be taken at present may generate extremely harmful damage to the environment, human beings, fauna, and flora of the planet. Limiting global warming to 1.5 Celsius involves large reductions in the emission of methane (CH4) and carbon dioxide (CO2). Thus, a strong demand in the bioenergy sector is necessary, highlighting the importance of using appropriate management measures which contribute to minimizing the problem, as is the case with the use of anaerobic digestion as a treatment for organic solid waste. The growing increase in the world population and the accelerated urbanization process of cities have resulted in the generation of excessive amounts of solid urban waste (Roth & Garcias, 2008), which, if poorly managed, contribute not only to the increase in damage caused to environment, but also inflict several problems in the social and economic aspect of modern society, thus aggravating the problem.