Thesis (MBA (Business Management))--University of Stellenbosch, 2007. / ENGLISH SUMMARY: Fossil fuel has been the preferred source for the production of transportation fuel for many years. However, this is not a renewable resource. Many conflicting reports have been published as to how long this resource will last. One thing is certain: eventually the supply of cheap crude oil will run out. It is therefore crucial to start the search for renewable alternatives now. There are a number of possible candidates vying for replacing fossil fuel as primary transportation fuel. Hydrogen, methanol, biodiesel and bioethanol all have the characteristics required of a good transportation fuel. It is unlikely that only one of these will replace oil. A more likely scenario would be that they all play a role in transportation in the future. Apart from being renewable, these alternatives have the further advantage of being less damaging to the environment, something that will become essential in future. Among the renewable alternatives, bioethanol has the second highest energy density. Currently, ethanol production worldwide almost exclusively uses sugarcane and maize as raw material. However, both these are food crops and using them for ethanol could lead to an increase in food prices. Furthermore, there is not enough agricultural land available to produce sufficient quantities of sugarcane and maize for ethanol to replace fossil fuel. Producing ethanol from plant material has the potential to meet the capacity requirements without impacting directly on food production. Approximately 180 million tons of agricultural biomass are produced in the United States each year, sufficient to produce 75 to 110 billion litres of ethanol. Despite its abundance, the technical challenges in converting cellulose to ethanol are significant. One major obstacle to the production of ethanol out of plant material is that most of the sugar in plant material is unavailable for fermentation by micro-organisms. In order to render the sugars in the cellulose fraction accessible to conversion, it is necessary to treat the plant fibres with a combination of chemical and enzymatic processes. Only when a complex mixture of enzymes is used, does it become possible to break down cellulose to glucose for subsequent fermentation to ethanol. Biomass processing by means of enzymes currently involves four separate biological steps: (i) production of enzymes (cellullases and hemicellulases), (ii) hydrolysis of cellulose and hemicellulose to sugars, (iii) fermentation of hexose sugars and (iv) fermentation of pentose sugars. Consolidated BioProcessing (CBP) will combine all these steps into one. However, CBP is not yet possible and the magnitude of research and developmental advancement required to realize this goal is significant. Both sugar and starch ethanol technologies are well established and major process advances are therefore unlikely. Currently there are no commercial-sized plants for the production of ethanol from lignocellulosics, however this is likely to change in the near future considering the progress made in this field during recent years. This study will focus on the current status of the bioethanol industry, as well as on the potential for future development. / AFRIKAANSE OPSOMMING: Fossielbrandstof was vir baie jare die hoofbron vir die produksie van brandstof vir die vervoerbedryf. Fossielbrandstof is nie ’n hernubare energiebron nie en daar is al baie gespekuleer oor presies hoe lank daar nog goedkoop olie beskikbaar sal wees. Baie min van die gepubliseerde bronne stem ooreen, maar almal is dit eens dat olie op een of ander stadium sal opraak. Om hierdie rede is dit noodsaaklik om nou reeds te soek na alternatiewe. Daar is ’n hele aantal hernubare alternatiewe wat gebruik kan word in die plek van olie. Waterstof, metanol, biodiesel en bioetanol beskik almal oor die nodige eienskappe om ’n effektiewe vervoerbrandstof te wees. Die hoofvoordeel van hierdie brandstowwe is dat hulle minder skadelik is vir die omgewing as olie, ’n eienskap wat baie belangrik sal wees in die toekoms. Die kans is eger skraal dat een van bogenoemde bronne die mark totaal sal oorheers soos wat olie tot op hede oorheers het. ’n Meer waarskynlik uitkoms sou wees dat al hierdie bronne op een of ander manier ’n rol gaan speel in die vervoerbedryf in die toekoms. Etanol het die tweede hoogste energie digtheid van die vier genoemde hernubare brandstowwe. Etanol word tans uitsluitlik van suikerriet en mielies geproduseer. Beide suikerriet en mielies is voedselgewasse en die gebruik daarvan vir brandstof kan lei tot ’n toename in voedselpryse. Daar is ook nie genoeg landbougrond beskikbaar vir die verbouing van suikerriet en mieles sodat genoeg etanol geproduseer kan word om fosielbranstof te vergang nie. Die vervaardiging van etanol vanaf lignosellulose het die potensiaal om etanolkapasiteitprobleme te oorkom sonder om direk met voedselproduksie te kompeteer. Ongeveer 180 miljoen ton landbouafval word jaarliks in die Verenigde State geproduseer, genoeg vir die vervaardiging van tussen 75 en 110 biljoen liter etanol. Die tegniese kompleksiteit gekoppel aan die omskakeling van sellulose na etanol is beduidend. Die belangrikste hindernis vir die produksie van etanol vanaf plantmateriaal is die feit dat die meeste van die suiker nie beskibaar is vir fermentasie deur mikroörganismes nie. Plantvesels moet daarom met ’n kombinasie van chemikalieë en ensieme behandel word om sodoende die suiker beskikbaar te maak vir omskakeling. Sellulose kan slegs met ’n komplekse mengsel van ensieme afgebreek word tot glukose wat dan daarna gefermenteer kan word tot etanol. Die verwerking van biomassa met behulp van ensieme behels tans vier afsonderlike biologiese stappe: (i) ensiemproduksie (sellulases en hemisellulases), (ii) hidrolise van sellulose en hemisellulose tot fermenteerbare suikers, (iii) fermentasie van heksose suikers en (iv) fermentasie van pentose suikers. Consolidate BioProcessing (CBP) poog om al vier hierdie stappe te kombineer. Ongelukkig is die CBP proses nog nie moontlik nie en daar moet nog baie navorsing en ontwikkeling gedoen word om dit ’n realiteit te maak. Beide die metodes vir suiker- en styseletanolproduksie is goed gevestig, dus is die kans vir beduidende verbeteringe klein. Daar is tans geen aanlegte van kommersiële grootte vir die produksie van etanol vanaf lignocellulose nie, maar dit gaan waarskynlik binnekort verander as ’n mens die vordering in ag neem wat daar onlangs gemaak is in hierdie veld. Hierdie studie fokus op die huidige stand van sake in die etanolbedryf en die ontwikkelingsmoontlikhede vir die toekoms.

Thesis (MBA (Business Management))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The objective of the study was to establish whether a small-scale biomass renewable energy project that uses waste fruit and pomace as the predominant feedstock could be a feasible clean development mechanism (CDM) project. The study was based on the solid waste streams of a pome fruit processor. Renewable energy technologies that convert biomass into a methane rich gas were evaluated. These included the various anaerobic digestion technologies that yield biogas and gasification technologies that yield syngas. Gasification was not found to be a feasible technology due to the moisture content requirement of less than 20% against that of the biomass of 70-80% and due to the low bulk density of the biomass of 250 kg/m3 versus the required minimum of 500kg/m3. The biogas could either be fired in a combined heat and power (CHP) unit or in a dual fired burner with heavy furnace oil (HFO). Feeding the thermal energy and electricity from the CHP unit back to the processor or supplying the electricity to the national electricity grid was considered. The plant would supply electricity to the national electricity grid as an Independent Power Producer (IPP). Eskom would be the renewable energy purchasing agent (REPA) that purchases the electricity at an anticipated R0.96/kWh under a power purchase agreement (PPA) in terms of the renewable energy feed-in tariff phase II (REFIT) guidelines. The anticipated revenue for electricity was six fold the coal offset cost of R0.16/kWh, while there was no demand for the heat energy after the processing season, thus firing biogas in a dual fired burner was not feasible. The most feasible technology was the anaerobic digestion of the biomass using a continuous stirred tank reactor (CSTR) process followed by a CHP unit that feeds the heat to the processing facility and the electricity into the national electricity grid. Waste fruit and wet pomace would be codigested with abattoir waste during the operating season. Dried pomace, abattoir waste, waste fruit and any other non-woody material from the surrounding farms and packhouses would be digested after the season to optimize the utilisation of the plant capacity. A capacity of 11 dry tons per day for the case study at a cost of R13 138 889 yielded an IRR of 15.2% and a net present value (NPV) of - R1 498 616 based on a discount rate of 18%, when excluding revenue from the sale of carbon emission reductions (CERs). Therefore, without the sale of CERs, this project would be rejected as a non-feasible investment. The project is eligible for CDM registration as a small-scale renewable energy project activity. No barriers were identified that would prevent the registration of this project activity as a CDM project in South Africa. The sale of CERs increased the NPV of the optimum solution to R156 483 and the IRR to 18.3%. Registering the project as a CDM project activity improved the feasibility of the project to the extent that it was marginally feasible. The fermentation and hydrolysis of the biomass into bioethanol was investigated as an alternative to the generation of heat and electricity. Although the technology is proven, no facilities were identified that use spoilt apples or apple pomace as the substrate. This increased the risk of the project and a discount rate of 24% was set when calculating the project NPV. This project activity yielded an NPV of - R1 296 057 when excluding CDM revenue. The feasibility improved to an NPV of - R263 507 and an IRR of 23.4% when taking the additional revenue from the sale of CERs into account. This project alternative was only marginally out of the money. With the development of newer technology, this alternative could prove to be more attractive in the future.

Thesis (MBA)--Stellenbosch University, 2011. / The global energy industry is actively moving toward renewable energy sources in order to meet the ever-increasing demand for energy in a sustainable manner. The South African government, however, has only recently begun creating an environment which is truly conducive to investment into the renewable energy industry. Metso, a Finnish multi-national corporation, has a strong global position in the field of biomass-based power generation for heat, power or combined heat and power applications. The corporation has developed a modular biomass-based power generation solution for power generation in the 3MW to 10MW range, which is highly automated and can essentially operate without the need for extensive human intervention and is known as the Metso Bio-energy Solution. Considering the current state of the South African energy environment, Metso management requested the researcher to investigate the opportunities that exist in the South African market for Metso’s Bio-energy Solution, and to propose a market entry strategy which Metso should follow in order to enter the South African market. In the findings, the researcher observed that South Africa has a clear potential for the development of a bio-energy industry for power generation, although the limited availability of biomass in certain regions and the various harvesting methods in industries such as the forestry and sugar industries do restrict the access to this resource. The municipal solid waste industry appears to be an area of interest as well, although very little information exists regarding the volumes of waste available and sorting practices, which may be required in order to access these resources. Interviews were held with experts in the field of energy, renewable energy and energy policy in order to obtain opinions on the market potential for Metso’s Bio-energy Solution. The general perception of all interviewees was that the technology has its place within the South African energy mix. The interviewees, however, did confirm that there currently appears to be a major focus on wind and solar energy in the country, although biomass technology may well be a better solution due to its baseload capabilities. It was found that the local policy environment, the lack of government initiative on renewable energy licensing and unclear tariff structures have all inhibited the proliferation of the renewable energy industry. In many cases, frustration with power outages and policy delays has caused companies to invest in biomass co-firing facilities for their own consumption. The factors for success for biomass-based technologies in the South African market would appear to be directly linked to job creation potential, access to reliable and sustainable biomass resources and access to investment capital, from both private equity and the state. It is the recommendation of the researcher that Metso enters into a joint venture with a large international environmental finance company, which would base their business model on the technology provided by Metso, whilst securing the political and financial support for projects of this nature in the country.

Thesis (MBA)--Stellenbosch University, 2012. / Bioethanol and biodiesel are currently the main biofuels. The United States of America and Brazil are the major bioethanol producers from maize and sugar cane respectively. European and Asian countries produce and consume biodiesel as transportation fuel. Generally, governments want to avoid importing biofuels, since this erodes the advantage of fuel security from growing fuel locally. There are however opportunities for many African countries to export to Europe and the United States of America, since they have preferential import tax exemption agreements with African countries. Sub-Saharan Africa has large potential to produce biomass. Inherently, South Africa has poor potential to produce biomass, due to the climatic conditions and water scarcity. However, South Africa has infrastructure, skills, commercial farmers and, importantly, government policy on biofuels. These advantages should be leveraged to optimise gains from a biofuel industry. A biofuels industry holds potential in terms of job creation and rural development gains, apart from the advantages of fuel security, greenhouse gas (GHG) emission reductions, stimulation of the agricultural sector, and reduced fuel imports with the balance of payment advantages. The South African government aims to develop rural communities in former homeland areas. If degraded land in these areas is recovered and used for production of biofuels, the environmental benefits are immediate and substantial. Fuel crop production in these areas does not compromise food security nor does it result in further deforestation. Creating jobs in rural areas can contribute to reduction of poverty. The Department of Minerals and Energy (DME) published its strategy in 2007. This excluded maize as permitted bioethanol feedstock, it sets a two per cent liquid fuels penetration target, and gave fuel tax exemptions for biodiesel and bioethanol. The biofuels would be distributed through voluntary low concentration blending into petroleum products by oil companies. The industry would be regulated and producers require licensing through the South African Revenue Service (SARS). The license conditions were mainly related to the type of feedstock, where it was produced, volumes produced, local consumption, environmentally friendliness, compliance with broad based black economic empowerment requirements and it should not compete with food sources. The strategy is up for review after the initial five years phase. Currently there are no commercial bioethanol fuel production plants in South Africa and only some small scale biodiesel production plants with very limited outlets to consumers. With all the apparent advantages, why is nothing happening in the industry? Business is not showing interest, proving that the economic conditions are not favourable. The government wants to control the production side to maximise the gains from it, but instead of assisting the industry, it has practically inhibited it from getting started. The consumers must also be prepared to accept the new fuels. Awareness, education and a culture of sustainable use are vital to create the required market. This is an exciting industry with potential benefits to South Africa and its society as a whole, but the fundamental elements of business must be in place in order for it to become self-sustainable.

Submitted in fulfillment for the requirements for the degree of Doctor of Technology: Biotechnology, Durban University of Technology, Durban, South Africa, 2015. / Main focus of this study is to investigate the enzymatic-conversion of microalgal lipids to biodiesel. However, preceding steps before conversion such as drying of microalgal biomass and extraction of lipids were also studied. Downstream processing of microalgae has several challenges and there is very little literature available in this area. S. obliquus was grown in the pilot scale open pond cultivation system for biomass production. Different techniques were studied for biomass drying and extraction of lipids from harvested microalgal biomass. Effect of these drying and extraction techniques on lipid yield and quality was assessed. Energy consumption and economic evaluation was also studied. Enzymatic conversion of microalgal lipids by extracellular and whole cell lipase application was investigated. For both applications, free and immobilized lipases from different sources were screened and selected based on biodiesel conversion. Process parameters were optimized using chosen extracellular and whole cell lipases; also step-wise methanol addition was studied to improve the biodiesel conversion. Immobilized lipase was studied for its reuse. Final biodiesel was characterized for its fuel properties and compared with the specifications given by international standards. Enzymatic conversion of microalgal lipids was compared with the conventional homogeneous acid-catalyzed conversion. Enzymatic conversion and chemical conversion were techno-economically investigated based on process cost, energy consumption and processing steps. Freeze drying was the most efficient technique, however at large scale economical sun drying could also be selected as possible drying step. Microwave assisted lipid extraction performed better compared to sonication technique. Immobilized P. fluorescens lipase in extracellular application and A. niger lipase in whole cell application showed superior biodiesel conversion. The extracellular immobilized P. fluorescens lipase showed better biodiesel conversion and yields than the immobilized A. niger whole cell lipase. Both the enzyme catalysts showed lower biodiesel conversion compared to conventional chemical catalyst and higher processing cost. However, techno-economic analysis showed that, the reuse potential of immobilized lipases can significantly improve the economics. Fewer purification steps, less wastewater generation and minimal energy input are the benefits of enzymatic route of biodiesel conversion. Microalgae as a feedstock and lipase as a catalyst for conversion makes overall biodiesel production process environmentally-friendly. Data from this study has academic as well as industrial significance. Conclusions from this study form the basis for greener and sustainable scaling-up of microalgal biodiesel production process. / D

Thesis (M.Com. (Development Theory and Policy))--University of the Witwatersrand, Faculty of Commerce, Law and Management, School of Economic and Business Sciences, 2016. / Energy security, particularly liquid fuels, is a vital economic goal for both developed and developing nations.As a region, SADC has large coal, oil and gas reserves,and land for potential crop production for biofuels, yet access to liquid fuels is still a major constraint to economic and social development. Some coal is utilised in the region for petrochemical industries, power generation, and for heating. Crude oil reserves are largely exported due to the lack of refineries and pipelines in the region. Whilst biofuels production is in its infancy. This paper explores the challenges and opportunitiesthe SADC region faces in developing refining capacity and in investing in new CTL/GTL facilities as well as liquid fuels from renewable energy resources. A primary focus will be on Malawi and her neighbouring states, as a case study. / MT2017

Cette thèse explore les possibilités en droit européen pour promouvoir les carburants et combustibles d'origine agricole et forestier. Ce sujet est d'intérêt pour l'Europe, parce qu'il peut à la fois offrir une source d'énergie plus propre (c'est une source d'énergie renouvelable pouvant réduire les émissions en gaz à effet de serre et des gaz polluants), un nouveau déboucher pour la surcapacité de l'agriculture européenne et réduire la dépendance énergétique de l'Europe et ainsi sa sécurité d'approvisionnement.<p>La thèse commence en présentant brièvement les différentes politiques de l'Union Européenne qui concernent les biocarburants et -combustibles et en énumérant les mesures déjà pris dans le cadre de ces politiques qui donnent du soutien à cette technologie. Ceci inclut les différentes programmes de financement de recherche ou du développement régionale, les mesures de protection de l'environnement concernés, le traitement de cette source d'énergie par les systèmes fiscales réglés au niveau européen (accises et TVA)et surtout les actions dans le cadre de la Politique Agricole Commune (PAC), avec son soutien pour les différentes secteurs agricoles qui peuvent fournir les matières premières pour ces carburants/combustibles. Ceci révèle que l'action actuelle en faveur de cette technologie n'est pas une action intégrée mais de caractère ponctuel et ancillaire. En fait avec beaucoup des mesures existantes, la promotion des biocarburants/biocombustibles n'est pas le but principal, mais un but ancillaire - comme un soutien de cette technologie peut aider à atteindre le but principal,elle est soutenue. Par exemple, dans le cadre de la PAC, le soutien aux biocarburants actuellement est du au souhait de réduire la capacité de production d'autres produits en crise.<p>Ma thèse par contre, propose des actions qui sont développés spécifiquement avec le but de promouvoir cette technologie, où ce résultat n'est pas le sous-produit du souhait d'atteindre un autre but. Il y a d'abord des propositions sur comment le droit européen peut agir ici sans des modifications majeures,en étendant certaines mesures existantes ou en appliquant d'autres par analogie pour inclure un soutien à cette source d'énergie.<p>Suit la proposition d'une action intégrée du droit communautaire pour l'intervention en faveur des biocarburants/biocombustibles moyennant un nouveau type d'organisation commune de marché:<p>Ceci est une application du droit tout à fait innovante dans cette domaine. Il est proposé d'organiser l'intervention moyennant des appels d'offre avant la campagne de culture. Les agriculteurs doivent alors planifier leur production en avance et essayer de trouver des débouchés pour leurs produits avant de commencer à produire.<p>Sur base des résultats ainsi obtenus, ils demandent du soutien pour obtenir un revenu net équitable. Cette intervention peut prendre tous les formes actuels comme l'achat, aide directe, restitutions à la production,etc.<p>La thèse ensuite examine la conformité de le méchanisme avec les exigences de base du droit européen,rappellant les principes fondamentaux de droit européen, comme le respect des droits de l'homme, la non-discrimination, le droit à la propriété et la proportionalité,qui doivent être respectés par toute action législative sur le niveau européen.<p>Puis il y a l'analyse des avantages de cette manière d'intervenir: <p>En obligeant les producteurs de demander du soutien avant l'ensemencement, tous les décisions sur les types de produit, prix, quantités, etc. doivent être déjà prises et, par conséquent, l'organisme d'intervention n'est pas confronté avec des faits accompli après la récolte.<p>Au contraire, il connaît à l'avance la production et son niveau envisagée. Ceci offre la possibilité d'éviter des problèmes: l'intervention a le moyen avec l'outil du appel d'offre et le soutien accordé par conséquence, de diriger cette production envisagée en provoquant des changements avant que la production est entamé. De cette manière on peut éviter des surproductions - en refusant des demandes de soutien au delà d'un certain seuil(obligeant les producteurs à chercher des alternatives)ou - en demandant une réduction de la productivité spécifique(exigeant une agriculture plus extensive) si on préfère du soutien spécifique (par unité produite)plus élevé pour combler l'écart entre le revenu de la production et un revenu considéré comme équitable. Cette manière d'intervenir permet aussi de cibler avec plus de précision le soutien aux producteurs qui en ont vraiment besoin en donnant de la priorité aux demandes des producteurs les plus désavantagés, p.ex. les exploitations familiales ou ceux avec une production écologique etc. Alternativement, en offrant plus de possibilités d'obtenir du soutien dans une certaine catégorie de production, ce système peut permettre de inciter d'autres à se convertir pour un type d'agriculture souhaité. Ceci peut donner une direction à l'évolution structurelle de l'agriculture. Actuellement ce souhait de diriger le type d'exploitation se fait par un soutien plus élevé, avec du gaspillage de ressources budgétaires. Le système des appels d'offre (de demandes de soutien)proposé individualise l'intervention pour mieux cibler le soutien à ceux qui en ont besoin sans la rigidité de quotas.<p>En plus, comme la décision sur le soutien est seulement prise après la formation de contrats de vente des produits (et par conséquence après fixation de leurs prix effectifs), ce système d'intervention en fait laisse plus de liberté au marché que les systèmes actuels, à l'exception des situations où l'évolution de la production (envisagée)risque de provoquer des problèmes et l'intervention par conséquence incite un changement des décisions prises. Normalement ces décisions commerciales ne sont pas influencés par le niveau de soutien accordé après. C'est un type de "deficiency payments" avec la possibilité d'intervenir de manière 'dirigiste' si des problèmes s'annoncent. / Doctorat en droit / info:eu-repo/semantics/nonPublished

O setor florestal apresenta impacto na economia do Brasil, com valores significativos no PIB, em exportações e geração de empregos. O país possui cerca de 7,74 milhões de hectares de florestas plantadas, o que corresponde a apenas 0,9% do território nacional. Os plantios podem ser realizados em áreas novas ou em áreas que já possuíam eucalipto no ciclo anterior. Neste caso, os tocos remanescentes representam um problema, dificultando o tráfego homogêneo de máquinas e influindo na qualidade das operações florestais. O aproveitamento dos resíduos, por meio da retirada dos tocos remanescentes, pode contribuir para minimizar esses problemas, trazendo benefícios econômicos e energéticos. Com isso, o objetivo deste trabalho consistiu em analisar a viabilidade operacional, econômica e energética de um sistema mecanizado florestal para o aproveitamento de resíduos florestais (toco). Para tanto, um modelo, em planilha eletrônica, foi desenvolvido. Os dados referentes à capacidade de trabalho dos equipamentos envolvidos foram obtidos por meio de um estudo de tempos e movimentos das operações mecanizadas de destoca, baldeio, processamento e transporte. O modelo foi empregado para avaliação de cenários e identificar variáveis críticas. Os resultados evidenciaram que o sistema mecanizado empregado para a destoca e retirada dos resíduos, tocos e raízes, é viável operacional e economicamente e tem um desempenho energético favorável. As restrições do uso desse sistema referem-se à área mínima e a distância de transporte, e que as variações na produtividade, no preço de venda da biomassa e na capacidade de campo operacional impactam sensivelmente na viabilidade econômica do projeto. / The forest sector plays an important role in Brazil\'s economy, with significant share in the GDP, exports and job creation. Brazil has about 7.74 million ha of planted forests, accounting for only 0.9% of the national territory. Plantations may occur in new areas or in areas that already had a previous eucalypt cycle. In this case, the remaining stumps represent a problem hindering the smooth traffic of machinery and affecting forest operations. The use of waste by removing the remaining stumps can help to minimize these problems, bringing economic and energy benefits. Therefore, the aim of this study was to examine the operational, economic and energy viability of a mechanized-harvest forest system for the use of forest waste (stumps). To this end, a model was developed in spreadsheet. The data related to the work capacity of the equipment involved were obtained by means of a time and motion study of mechanized operations of stumps removal, carrying, processing and transportation. The model was used to evaluate scenarios and identify critical variables. The results showed that the mechanized system used for stumps removal, stumps and roots, is operationally and economically viable and has a favorable energy performance. Restrictions of using this system refers to the minimum area and distance of transport. In addition, variations in productivity, selling price of biomass and field operational capacity significantly affect the economic viability of the project.

Da substituição da colheita manual de cana queimada pela mecanizada de cana crua, decorre grande demanda por pesquisas relacionadas aos efeitos do palhiço, residual da colheita, sobre a cana soca e sobre o ambiente de produção. O presente trabalho teve por objetivo estudar os efeitos do sistema de colheita e do manejo do palhiço residual sobre o desenvolvimento das soqueiras de cana-de-açúcar e sobre algumas propriedades físicas e químicas do solo. O experimento foi instalado em área de colheita mecanizada de cana-de-açúcar, variedade SP91- 1049, conduzido ao longo do ciclo da primeira soca, delineado em blocos completos casualizados, com quatro repetições e os seguintes quatro tratamentos: palhiço em área total (não manejado); remoção do palhiço de sobre as linhas de cana (desaleiramento); palhiço aleirado; e palhiço queimado. Uma medida mensal de temperatura do solo foi feita até o 9º mês após o corte. A biometria foi feita mensalmente até 8 meses após o corte, avaliando-se o perfilhamento da cana e o crescimento inicial da parte aérea. Próximo ao final do ciclo foram feitas análises químicas de solo e de folhas de cana, análises físicas de solo não deformado, avaliação da distribuição da umidade e do sistema radicular no perfil do solo, e análises tecnológicas de amostras de cana para avaliação da maturação. Por ocasião da colheita, pesou-se a produção. O maior efeito do palhiço sobre a cana-de-açúcar foi reduzir o perfilhamento inicial, sendo que o desaleiramento mostrou-se a forma de manejo do palhiço mais eficaz em mitigar o efeito negativo do mesmo sobre o perfilhamento inicial. O aleiramento, além de ser menos eficaz nesse sentido, induziu um perfilhamento inicial deveras heterogêneo. Quanto às propriedades químicas do solo, o palhiço não causou efeito significativo sobre os teores de MO, CTC, Al e pH; entre os nutrientes, apenas o manganês sofreu efeito significativo dos tratamentos, apresentando menor teor sob palhiço em área total do que onde o palhiço foi queimado. Quanto às propriedades físicas do solo, o palhiço favoreceu uma pequena compactação, indicada por redução da aeração do solo na capacidade de campo; além da redução da temperatura do solo, significativa só nos primeiros 6 meses após o corte. Sobre a distribuição da água no perfil do solo, avaliada no 11º mês após o corte e depois 2 semanas sem chuva, na camada de 0-20 cm a umidade foi significativamente maior sob palhiço em área total do que onde o palhiço foi queimado; e em profundidades maiores não houve diferença significativa devida aos tratamentos. Não obstante, sobre a distribuição do sistema radicular no perfil do solo, os tratamentos não produziram nenhuma diferença significativa. / Replacing the manual harvesting of burnt sugarcane for green sugarcane mechanical harvesting, follows a great demand for research about the effects of straw on sugarcane ratoon and on the production environment. This work aimed to study the effects of the harvest and of straw management on the development of the sugarcane ratoon and on some physical and chemical properties of soil. The experiment was conducted on an area of mechanical harvesting of sugarcane, variety SP91-1049, conducted during the first cycle of ratoon, the experimental design was randomized blocks with four repetitions and the following four treatments: straw in total area; straw removed from the sugarcane lines; with the straw between four lines moved to a ridge between two lines (straw tilling); and burnt straw. Measurements of soil temperature were made monthly, until the 9th month after the harvest. Biometric measurements were performed monthly until 8 months after harvesting, evaluating the sugarcane tillering and the initial growth of the tillers. Near the end of the cycle, chemical analyses of soil and of sugarcane leaves, and physical analyses of not deformed soil samples were performed; the distribution of moisture and of root system into the soil profile were evaluated; and technological analysis of sugarcane samples were made to evaluate the maturity stage of sugarcane. At the harvest, the production was weighed. The biggest effect of straw on sugarcane was reducing the initial tillering, and the removal of straw from sugarcane lines proved to be the more effective management to mitigate the negative effect of straw on the tillering. The straw tilling, less effective in this sense, also induced a very heterogeneous initial tillering. Regarding the soil chemical properties, straw did not cause significant effect on the levels of organic matter, capacity of cations exchange, Al and pH; among the nutrients, only Mn had a significant effect of the treatments, with lower content under straw in total area than where straw was burned. Regarding the physical properties of soil, straw provided a little compaction, indicated by reduction of the soil aeration at field capacity; as well as significant reducing of soil temperature only in the first 6 months after harvest. On the distribution of water in the soil profile, measured 11 months after harvest and after 2 weeks without rain, in the depth of 0 to 20 centimeters, moisture was significantly higher under straw in total area than where straw was burned, and in bigger depths there were no significant difference due to treatments. However, on the distribution of root system in the soil profile, the treatments produced no significant difference.

Thesis (Doctor of Engineering in Chemical Engineering)--Cape Peninsula University of Technology, 2018. / Lignocellulosic biomass (agro-waste) has been recommended as the most promising feedstock for the production of bioalcohols, in the biofuel industry. Furthermore, agro-waste is well-known as the most abundant organic matter in the agricultural and forestry product processing industry. However, the challenge with utilizing agro-waste as a feedstock is its highly recalcitrant structure, which limits hydrolysis to convert the holocelluloses into fermentable sugars. Conventional pre-treatment methods such as dilute acid, alkaline, thermal, hot water and enzymatic, have been used in previous studies. The challenge with these conventional methods is the generation of residual toxicants during the pretreatment process, which inhibits a high bioalcohol yield, by reducing the microbial populations’ (fermenter) ability to be metabolically proficient during fermentation. Numerous studies have been developed to improve the engineered strains, which have shown to have an ability to reduce the inhibition and toxicity of the bioalcohols produced or by-products produced during pre-treatment, while enhancing the bioalcohol production. In the present study (chapter 5), evaluation of common conventional methods for the pretreatment of the mixed agro-waste, i.e. (˃45µm to <100µm) constituted by Citrus sinensis, Malus domestica peels, corn cobs from Zea mays and Quercus robur (oak) yard waste without a pre-rinsing step at a ratio of 1:1 at 25% (w/w) for each waste material, was undertaken, focusing on hot water pre treatment followed by dilute acid (H2SO4) pre-treatment. To further pretreat the mixed agro-waste residue, cellulases were used to further hydrolyse the pre-treated agro-waste in a single pot (batch) multi-reaction process. The TRS concentration of 0.12, 1.43 and 3.22 g/L was achieved with hot water, dilute acid and cellulases hydrolysis as sequential pretreatment steps, respectively, in a single pot multi-reaction system. Furthermore, a commercial strain was used to ascertain low (C1 to C3) and high carbon content (C4+) bioalcohol production under aerobic conditions. Multiple bioproducts were obtained within 48 to 72 h, including bioethanol and 1-Butanol, 3-methyl, which were major products for this study. However, undesirable bio-compounds such as phenolics, were detected post fermentation. Since multiple process units characterised by chemical usage and high energy intensivity have been utilized to overcome delignification and cellulolysis, a sustainable, environmental benign pretreatment process was proposed using N. mirabilis “monkey cup” fluids (extracts) to also reduce fermenter inhibitors from the delignification of mixed agrowaste; a process with minimal thermo physical chemical inputs for which a single pot multi-reaction system strategy was used. Nepenthes mirabilis extracts shown to have ligninolytic, cellulolytic and xylanolytic activities, were used as an enzyme cocktail to pretreat mixed agro-waste, subsequent to the furtherance of TRS production from the agro-waste, by further using cellulase for further hydrolysis. N. mirabilis pod extracts were determined to contained carboxylesterases (529.41±30.50 U/L), β-glucosidases (251.94±11.48 U/L) and xylanases (36.09±18.04 U/L), constituting an enzymatic cocktail with a significant potential for the reduction in total residual phenolic compounds (TRPCs). Furthermore, the results indicated that maximum concentration of TRS obtainable was 310±5.19 mg/L within 168 h, while the TRPCs were reduced from 6.25±0.18 to 4.26 ±0.09 mg/L, which was lower than that observed when conventional methods were used. Overall N. mirabilis extracts were demonstrated to have an ability to support biocatalytic processes for the conversion of agro-waste to produce fermentable TRS in a single unit facilitating multiple reactions with minimised interference with cellulase hydrolysis. Therefore, the digestive enzymes in N. mirabilis pods can be used in an integrated system for a second generation biorefinery.