This study examined the effects of replicating woodland soil surface horizonation on the nutrient status of underlying soils and the initial establishment and growth of trees. A total of 283 container grown trees were planted in a bufferzone around a future landfill site. Control amendments consisted of an 8 cm layer (0.5 m3) of wood chips applied in a circular area of 4.6 m2 around the trees' planting pit. For the treatment, a 2.5 cm layer of composted biosolids (0.15 m3 or 80 Mg/ha) was applied in a circular area of 4.6 m2 around the trees' planting pit followed by an 8 cm layer (0.5 m3) of wood chips. The results indicate that the replication of woodland soil surface attributes using composted biosolids can significantly improve the nutrient status of underlying soil. Some significant effects were seen under control conditions, too. However, the effects on tree establishment and growth parameters were, for the most part, not statistically significant.

M.Sc. (Zoology) / Please refer to full text to view abstract

Comme dans les pays du Nord riches, il y a également une augmentation de la production de déchets organiques dans les pays du Sud moins avancés. Connues sous l'appellation de Matières Organiques Exogènes (MOEx), les déchets organiques peuvent être valorisables comme engrais ou amendement pour les sols agricoles ou bien une nouvelle source de biomasse pour la production d'énergie. L'utilisation raisonnée d'une MOEx exige toutefois une connaissance scientifique approfondie de leur nature et de leurs impacts sur l'environnement. Des analyses conventionnelles en laboratoire et des expérimentations doivent être effectués pour maîtriser leur structure complexe liée à leurs propriétés physiques, chimiques et biochimiques. Celles-ci sont généralement longues et onéreuses. Dans notre étude, la spectroscopie proche infrarouge (SPIR) a été choisie comme une alternative aux méthodes classiques pour la caractérisation de ces MOEx en milieu tropical humide. Les objectifs de notre travail sont (1) de montrer que la SPIR est une méthode appropriée pour la prédiction des caractéristiques de MOEx, (2) pour caractériser les MOEx en termes de leur potentiel agronomique et leur potentiel énergétique et (3) pour élaborer une typologie, construite à partir des données prédites par la SPIR, qui prend en compte quelques impacts négatifs liés à l'utilisation des MOEx. L'ensemble des données a inclus plus de 2000 échantillons de MOEx couvrant une large gamme de MOEx fraîches ou transformées issues de l'élevage, de la ville et des agroindustries. Le spectre SPIR de chaque EOM a été acquis. En plus des caractérisations classiques de laboratoire (les dosages de carbone, azote, phosphore, potassium, etc.), d'autres expérimentations ont été conduites en vue d’évaluer (1) les potentiels « positifs » des MOEx : (i) suivi de la minéralisation du carbone et de l'azote mesurée dans des conditions contrôlées pour une valorisation agronomique, (ii) détermination du pouvoir calorifique et du potentiel méthanogène pour une valorisation énergétique ; et (2) les potentiels « négatifs » des MOEx : (i) dénitrification potentielle et (ii) phytotoxicité en présence d’éléments trace métallique. Pour élaborer la typologie, la méthode SIRIS (Système d'Ingration des Risques par Interaction des Scores) a été appliquée pour formaliser les étapes d'une procédure logique menant à une classification des MOEx selon l'objectif de l'orientation de recyclage. La diversité des MOEx est illustrée à titre d'exemple par une large gamme des teneurs en (i) C (de 2 à 64 gC.100g-1MS), (ii) N (de 0,2 à 14gN.100g-1MS), (iii) P total (0,01 à 16gP.100g-1MS), K total (0,04 à 30 gK.100g-1MS). En prenant en compte l'ensemble des MOEx, les étalonnages des modèles SPIR sont acceptables pour la prédiction des teneurs en C, en N, en P et en K. Pour les potentiels « positifs » des MOEx (1) suivant les types de MOEx 102 à 955 kgMO.t-1MOEx pourraient être stockées dans le sol pour le maintien de la fertilité, (2) les pouvoirs calorifiques des MOEx varient de 7 à 28 MJ.kg-1MS et les potentiels méthanogènes vont de 69 à 488 NmlCH4.g-1MO. Quant aux potentiels négatifs, que ce soit pour les émissions de N2O ou pour la phytotoxicité des ETM, une forte interaction entre les propriétés du sol (pH, texture, …) avec les MOEx masque souvent certains effets. La méthode SIRIS a permis de classifier les MOEx selon un processus simple basé sur le classement de critères et de scores d'auto-pénalisation. Cette approche est intéressante en l'absence de données précises qui sont souvent difficiles à obtenir. L'aide des prédictions par la SPIR nous a été utile pour cette démarche d'orientation de la valorisation agronomique et/ou énergétique des MOEx. Des approches socio-économiques devraient compléter notre étude pour aboutir à l'orientation finale de valorisation des MOEx. / As observed in northern/rich countries, there is an increase in the production of organic wastes in southern/less advanced countries. So called, Exogenous Organic Matter (EOM), they can be a valuable fertilizer or amendment for agricultural soils or a new supply for energy production. The safe utilisation of EOM requires an in-depth scientific knowledge of their nature and impacts on the environment. Laboratory analysis and experiments have to be carried out in order to know their complex structure related to their physical, chemical and biochemical properties. These techniques represent a relatively high cost and are time consuming. In this study, the near infrared spectroscopy (NIRS) was chosen as an alternative to classical methods for laboratory characterisations of tropical EOM. The objectives of this study are (1) to show that NIRS is a suitable method for predicting EOM characteristics (2) to characterize EOM in terms of their agronomic potential and/or energetic potential, and (3) to elaborate a typology, build with predicted parameters by NIRS, taking into account some environmental impacts of the different utilisations of EOM.The dataset included more than 2000 EOM samples covering a broad range of fresh and transformed organic materials. Each EOM was scanned using a NIR spectrometer from 1100nm to 2500nm. In addition to the classical laboratory characterisations (dosages of total carbon, nitrogen, phosphorus, potassium), other experiments have been carried out: (1) for “positive” potentials: (i) C and N mineralization measured in controlled conditions (for an agronomic use), (ii) determination of High Heating Value and Biochemical Methane Potential (for an energetic use) and (2) for “negative” potential or risk: phytotoxicity assessment due to trace elements, and the determination of potential nitrous oxide emission. To elaborate the typology, the SIRIS method (System of Integration of Risk with Interaction of Scores) was carried out in order to formalize the steps of a logical procedure, leading to a decision according to objective of the recycling orientation.Diversity of EOM is illustrated by the variability of (i) C contents (from 2 to 64 gC.100g-1DM); (ii) N contents (from 0.2 to 14gN.100g-1DM); (iii) total P contents (from 0.01 to 16gP.100g-1DM),(iv) total K contents (from 0.04 to 30 gK.100g-1DM). When taking into account all EOM without regarding their nature, acceptable predictive models were obtained with NIRS calibration for estimating C, N, total P and total K contents for EOM.“Positive” potential assessment provided information about (1) remaining organic carbon might be stocked into soil after applying EOM (from 102 to 955 kg.t-1TOM) (2) High Heating Value of EOM when recycling as a supply of small scale combustion or thermo chemical conversion (from 7 to 28 MJ.kg-1DM), (3) Biochemical Methane Potential after EOM anaerobic digestion (from 69 to 488 NmlCH4.g-1TOM). Both “negative” potential which took into account phytotoxicity due to trace elements and nitrous oxide emissions were highly interacted on the soil properties (pH, texture). The SIRIS method appeared to be an efficient decision-making tool in this study. It made it possible to classify the EOM according to a simple process based on the ranking of criteria and a self-penalization scoring system. This approach can be used in the absence of accurate, reliable data, which are often difficult to obtain. The help of NIR prediction was useful for better orientate the EOM valorization between soil fertilization and energy production. Further concern will be focused on socio-economical approach in order to complete the final destination of EOM re-use.

[pt] O espaço urbano carioca funciona como um instrumento político e ideológico manipulado por atores hegemônicos que detêm o capital. O uso intencional do espaço cria uma iniquidade na distribuição dos serviços básicos, assim como, dos efeitos negativos do crescimento urbano expondo as áreas periféricas e a população de baixa renda a condições que atingem diretamente sua existência e qualidade de vida. O objetivo desta dissertação é analisar os problemas ambientais, sociais e econômicos decorrentes da criação de territórios do lixo em bairros de população de baixa renda, demonstrando que os interesses econômicos acabam por impor exteriorizações negativas do crescimento urbano a parcelas mais pobres da população em uma dinâmica de injustiças sociais que tiveram início no final do século XIX e se agravam nos dias atuais. Analisamos o processo de criação de quatro grandes territórios do lixo da cidade do Rio de Janeiro, tendo como destaque o Aterro Metropolitano de Jardim Gramacho. Neste analisamos as condições socioeconômica dos catadores de material reciclável, acompanhamos as discussões em torno de seu encerramento e a construção de um novo território do lixo. É possível compreender através de nossa análise que mesmo com as questões ambientais ganhando destaque no cenário nacional e internacional a dinâmica de aproximar os vazadouros de lixo das áreas carentes continua a mesma. / [en] The urban area of Rio de Janeiro serves as an ideological and political tool manipulated by hegemonic facts holding the capital. The intentional use of space creates an inequity basic delivery services , as well as the negative effects of urban growth in the outlying areas and expose in low-income conditions that directly affect their lives. The goal of this dissertation is to check the environmental matters, social and economic impact s of the trash territories creation in neighborhoods of low-income population, demonstrating the economic interests eventually imposed by the negative side of urban growth exteriorizations to the poorest side of the population in an injustice social dynamic that began in the last nineteenth century and it gets worse and worse nowadays. We analyze the process of creating four major areas of the city garbage in Rio de Janeiro, with the highlight the Metropolitan Landfill of Jardim Gramacho. In analyzing the socioeconomic conditions of recyclable material collectors, we follow the discussions about its closure and the construction of a new territory of garbage. You can understand through our analysis that even with environmental issues gaining prominence in the national and international setting to bring the garbage dumps of deprived areas remains the same.

En France, le cycle actuel de traitement du combustible usé génère un rejet de carbone 14 (déchet à vie longue, période  5730 ans) dans la géosphère. Ce document apporte des premiers éléments scientifiques et techniques pour évaluer la faisabilité d’un conditionnement du carbone, en tant qu’alternative aux rejets. Un matériau de type céramique a été choisi en raison d’un volume spécifique de 2 à 4 L.kg-1 de carbone, contre 12 à 17 L.kg-1 de carbone pour la cimentation actuellement mise en œuvre industriellement à l’étranger, afin de limiter les volumes produits en prévision d’un stockage géologique potentiel. La phase barytocalcite BaCa(CO3)2 a été étudiée en termes de (i) mode de synthèse compatible avec la forme existante du carbone 14 dans le cycle (ii) solidification par traitement thermique et (iii) résistance à la lixiviation. La barytocalcite a pu être obtenue par précipitation et densifiée à plus de 95% avec un frittage SPS de 30 min à 450°C sous 70 MPa typiquement, et ce, sans perte de carbone. Toutefois, le matériau présente une durabilité chimique limitée en eau pure à 30°C mais le carbone relâché précipite sous la forme de BaCO3 et CaCO3. Malgré cela, la potentialité de la barytocalcite en tant que matériau de conditionnement du carbone 14 reste réelle en raison des propriétés de rétention du site de stockage potentiel. Dans une seconde partie, ce document présente des résultats de caractérisation par diffusion et diffraction de rayons X appliqués à des matériaux liés à la R&D sur le traitement de déchets nucléaires. / In France, the current recycling process of the spent nuclear fuel produces a carbon-14 release in the geosphere (long life radionuclide, half-life  5730 y). This document provides scientific and technical data to evaluate the feasibility of carbon conditioning as an alternative to its release. A ceramic type material was chosen because of a specific volume of 2-4 L/kg of carbon, against 12-17 L/kg of carbon for the cementation process currently implemented industrially abroad, to limit the volumes in the case of a potential geological storage. The barytocalcite phase BaCa(CO3)2 has been studied in terms of (i) synthesis process compatible with the existing form of carbon-14 in the cycle (ii) solidification by heat treatment and (iii) leach resistance. The barytocalcite has been obtained by precipitation and densified to more than 95% with SPS sintering for 30 min at 450°C under 70 MPa, without any loss of carbon. This phase has a limited chemical durability in pure water at 30°C but the released carbon ions precipitate as BaCO3 and CaCO3. However the potentiality of barytocalcite as a carbon 14 conditioning matrix remains interesting because of the retention properties of the potential storage site. In a second part, this document provides the results of characterizations made by X-rays scattering and diffraction on different phases in relation with the nuclear waste conditioning R&D.

Este trabalho teve como objetivo a prospecção e caracterização de enzimas fúngicas, que degradam a biomassa, visando à aplicação no biobranqueamento da polpa de celulose. Para isto, foram selecionados 13 fungos filamentosos da Micoteca e entre estes Aspergillus versicolor e A. brasiliensis foram aqueles que se sobressaíram quanto à produção de xilanase, amilase, CMCase, avicelase e ?-glucosidase. As melhores condições de produção enzimática corresponderam à utilização de bagaço de cevada como fonte de carbono em meio SR (Segato Rizzatti) para xilanase, amilase e ?- glucosidase e meio M5 para CMCase, avicelase e FPase, nos cultivos incubados por tempos variáveis de 72 a 168 horas. Para otimizar a concentração da fonte de carbono e a temperatura nos cultivos foi realizado um Delineamentro Composto Central Rotacional. Como resultante da otimização do bioprocesso foram obtidos os extratos brutos: (i) meio BSR, para a produção de xilanase por A. brasiliensis, com 96 horas de cultivo estático, a 30°C, com bagaço de cevada 3% em meio SR; (ii) Meio VSR para amilase e ?-glucosidase a partir do A. versicolor, com 120 horas de cultivo estático, a 35°C, com bagaço de cevada 3,41% em meio SR; (iii) Meio VM5 para CMCase, avicelase e FPase de A. versicolor com 120 horas de cultivo estático, a 30°C, com bagaço de cevada 2% em meio M5. Lacase foi produzida por Trametes versicolor (iv), cultivado por quinze dias em Fermentação Submersa estática, a 30°C, em meio contendo vinhaça e água destilada (1:5 v/v), 1% de algodão e 0,1% de peptona. Paralelamente, a produção de xilanases de A. tamarii Kita (v) com bagaço de cevada 2,9% foi otimizada em meio ADAMS por 129 horas (recebendo a denominação - meio TKADAMS). Quanto à caracterização das enzimas de A. versicolor (xilanase) e A. brasiliensis (demais enzimas) a temperatura ótima de xilanase foi 70°C; amilase 60-65°C; CMCase 65°C; avicelase 50°C; FPase e lacase 60°C e ?-glucosidase 70-75°C. Quanto à estabilidade térmica, xilanase mostrou-se com 60% de atividade relativa por até 24 horas à 40°C e 30 minutos à 50°C. A 60°C mostrou-se pouco estável. A amilase mostrou-se estável por 24 horas a 40 e 50°C, com 80% da atividade relativa. CMCase e FPase mostraram-se pouco estável nas temperaturas citadas. Avicelase apresentou ativação quando exposta ao aquecimento de 40, 50 e 60°C. ?-glucosidase foi estável a 40°C por até 24 horas, com atividade relativa de 80%; a 50°C apresentou 60% de atividade relativa por 180 minutos e a 60°C exibiu 40% por até 30 minutos. Lacase foi estável a 50°C, com um t50 de 60 minutos; a 60°C teve atividade relativa próxima de 30%, por até 240 minutos e a 70°C apresentou 40% de atividade por 30 minutos. Quanto ao pH, xilanase apresentou uma faixa ótima de 4,0-5,0 e também entre 7,0-8,0. Amilase, CMCase, avicelase, FPase, ?-glucosidase e lacase apresentaram atividades mais expressivas na faixa de pH 4,0-5,5. Com relação à estabilidade ao pH em 24 horas, xilanase foi mais estável nos pH 5,5-7,0, amilase nos pH 5,0-6,5, CMCase, FPase e lacase em pH 4,5, avicelase em pH 3,0 e ?-glucosidase em pH 5,0-5,5. Quanto ao efeito de íons, CMCase e ?-glucosidase foram ativadas por K+, Zn+ e Ba2+; CMCase, ?-glucosidase e lacase foram ativadas por NH4+ e Ca2+; amilase, CMCase, ?-glucosidase e lacase foram ativadas por Co2+; amilase, CMCase e ?- glucosidase foram ativadas por Al3+ e Fe2+; xilanase, avicelase, CMCase e ?-glucosidase foram ativadas por Mn+; avicelase e CMCase foram ativadas por Ag+; lacase por EDTA; ?-glucosidase e lacase por Mg2+, CMCase por Hg2+ e xilanase, ?-glucosidase e lacase por Cu2+. Os extratos foram utilizados na formulação de coquetéis enzimáticos para biobranqueamento da polpa de celulose. A aplicação dos extratos BSR, VSR, VM5 sobre a polpa marrom não resultou em uma redução significativa do número Kappa quando comparados ao controle, uma vez que todos os extratos apresentavam uma coloração muito escura, a qual fora originada por componentes e pigmentos provenientes dos meios de cultivo dos micro-organismos com bagaço de cevada e que, consequentemente, interferiram na determinação do número Kappa. Desta forma, o coquetel otimizado teve como formulação: 20,3 mL do meio TKADAMS e 10 mL do extrato do meio produtor de lacase para cada 4 gramas de polpa tratada, pH 5,5; 35,9ºC, 48 horas. Este tratamento resultou na redução de 1,83 pontos no número Kappa da polpa marrom, representando uma eficiência de 20,3%, e aumento de 4,65 na alvura, em relação ao controle. A aplicação do coquetel nos resíduos lignocelulósicos ocasionou a formação máxima de 85 mg/mL de açúcares redutores, em 24 horas no tratamento do bagaço de cevada, e 25 mg/mL de açúcares redutores, em 3 horas no tratamento do bagaço de cana. A aplicação do coquetel nas polpas de papel reciclado ocasionou um maior destintamento. A aplicação do coquetel desenvolvido na polpa de celulose, nos resíduos lignocelulósicos e fibras secundárias mostrou-se promissora para biobranqueamento, biodegradação e destintamento destes, respectivamente. A aplicação de enzimas no processo de biobranqueamento da polpa de celulose é uma alternativa viável e que auxilia a redução de custos, água, energia e colabora com o meio ambiente. A lacase foi importante no biobranqueamento da polpa de celulose sendo que o aumento da escala de produção do T. versicolor para biorreator levou a uma produção 6,25 vezes maior comparada aquela em Erlenmeyer, provavelmente devido a aeração constante / This work aimed to prospect and characterize fungal enzymes, which break biomass, looking for the cellulose pulp biobleaching application. For this, 13 filamentous fungi of the Fungi Library were selected and among them Aspergillus versicolor and A. brasiliensis were those that stood out as inducers of xylanase, amylase, CMCase, avicelase and ?-glucosidase production. The use of barley bagasse as carbon source was the best condition for xylanase, amylase and ?-glucosidase production in SR medium (Segato Rizzatti) and M5 medium was the best for CMCase, avicelase and FPase production, in cultures incubated for 72-168 h. In order to optimize the concentration of the carbon source and the temperature of the cultures, a Central Composite Rotational Design was elaborated. (i) BSR extract, in SR medium for the xylanase production by A. brasiliensis, 96 hours, in static culture, at 30°C with barley bagasse 3%; (ii) VSR extract, in SR medium, for the amylase and ?-glucosidase from A. versicolor, 120 hours in static culture, at 35°C, with barley bagasse 3.41%. (iii) VM5 extract, in M5 medium for CMCase, avicelase and FPase from A. versicolor, 120 hours of static culture, at 30°C with barley bagasse 2%. Lacase was produced by Trametes versicolor (iv), in a medium containing vinasse and distilled water (1:5 v/v), cotton 1% and peptone 0.1%, for 15 days at 30ºC. In parallel, the production of a xylanase from A. tamarii Kita (v) with barley bagasse 2.9% was optimized in ADAMS medium for 129 hours (designated - TKADAMS medium). The thermal stability study showed that xylanase was stable with 60% of relative activity at 40°C for up to 24 hours and for 30 minutes at 50°C. At 60°C the enzyme was poorly stable. Amylase was stable for 24 hours at 40 and 50°C, with 80% of relative activity. CMCase and FPase was poorly stable at all temperatures tested. Avicelase was activated by the exposure at 40, 50 and 60°C. ?-glucosidase was stable at 40°C for up to 24 hours, with 80% of relative activity; at 50°C it showed a relative activity of 60% for 180 minutes and at 60° it showed 40% of relative activity for 30 minutes. Laccase was stable at 50°C with t50 for 60 minutes. At 60°C it showed an activity of 30% for up to 240 minutes and at 70°C it showed 40% of activity for 30 minutes. As for pH, xylanase showed the best activity in a range of pH 4.0-5.0 and 7.0-8.0. Amylase, CMCase, avicelase, FPase, ?-glucosidase and laccase showed expressive activities in a range of pH 4.0-5.5. The tests of pH stability in 24 hours showed that xylanase was stable at pH 5.5-7.0, amylase at pH 5.0-6.5, CMCase, FPase and laccase at pH 4.5, avicelase at pH 3.0 and ?-glucosidase at pH 5.0-5.5. The effect of ions showed that CMCase and ?-glucosidase were activated by K+, Zn+ and Ba2+; CMCase, ?-glucosidase and lacase were activated by NH4+ and Ca2+; amylase, CMCase, ?-glucosidase and lacase were activated by Co2+; amylase, CMCase and ?-glucosidase by Al3+ and Fe2+; xylanase, avicelase, CMCase and ?-glucosidase by Mn+; avicelase and CMCase by Ag+; lacase by EDTA; ?-glucosidase e lacase by Mg2+, CMCase by Hg2+ and xylanase, ?-glucosidase and lacase by Cu2+. The extracts were used in the formulation of enzymatic cocktails for cellulose pulp biobleaching. The application of BSR, VSR and VM5 extracts on the brown pulp did not result on a significant reduction of the Kappa number when compared to the control, on account of the dark coloration of these extracts caused by the components and pigments from the cultivation with the microorganisms and barley bagasse, which as a consequence, interfered in the determination of the Kappa number. Thus, an optimized cocktail was formulated: for each 4 grams of treated pulp 20.3 mL of TKADAMS extract and 10 mL of laccase extract, pH 5.5; 35.9°C, 48 hours. This treatment resulted in the reduction of 1.83 points in the Kappa number of the brown pulp, representing an efficiency of 20.3%, and a brightness increase of 4.65 when compared to the control. The application of the cocktail in the lignocellulosic residues resulted in the formation of 85 mg/mL of reducing sugars in barley bagasse treatment for 24 hours and, 25 mg/ml of reducing sugars in sugarcane bagasse treatment for 3 hours. The application of the cocktail in the recycled paper pulps caused a greater deinking. The application of the formulated cocktail in the cellulose pulp, lignocellulosic residues and secondary fibres was promising for biobleaching, biodegradation and deinking, respectively. The enzyme application in cellulose biobleaching is a viable alternative, which helps reducing costs, water, energy and collaborates with the environment. Laccase was important in the cellulose biobleaching and the increase of its production by T. versicolor through bioreactor led to a production 6.25 times higher than that in Erlenmeyer, probably due to the constant aeration

A dissertation submitted to the Faculty of Engineering, University of the Witwatersrand, in fulfillment of the requirements for the degree of Master of Science in Engineering / South Africa, like many other developing countries, is faced with rapid urbanisation with the associated increase in the pollution load. Much of this pollution is destined for our watercourses, that eventually run into storage reservoirs which may be used for drinking water or recreational purposes. This pollution is usually attributed to human waste products which include nitrogenous wastes, phosphates, microorganisms, organic material and litter, A 6km stretch of the Jukskei river just downstream of Alexandra Township, was used to determine the different biological, physical and chemical processes that pollutants undergo during natural assimilation, their rates and efficiencies of assimilation in rivers and their impact Oil the environment downstream of the urban area. "Grab" samples were taken over a period which included both low-flow and storm events. Due to the high concentration of nutrients in the run-off from Alexandra Township, the major changes seen were in the biological conversion of organic nitrogen compounds and ammonia to nitrates, in the BOD and in the concentration of dissolved oxygen in the river, with lows of 1.1 to 1.5 mg/l 02 being recorded at Alexandra. A rapid rise in the concentration of faecal coliforms has been seen with a high of 31 million/100 ml being recorded at Alexandra in September, 1994. Sedimentation at the Alexandra site is also a common occurrence with a lot of adsorbed pollutants being effectively removed from the water column with the suspended solids. The QUAL2E water quality model, used by the EPA in the United States, was used to model the reactions that the nutrients, BOD and DO undergo. BOD and DO were modelled very well with r of 0.98 and 0.94 being calculated respectively. QUAL2E did not model tile dissolved potlutants, dissolved phosphorus and ammonia very well with the observed results showing a greater reduction ill these pollutants. A method by which these pollutants adhere to SS and settle out was / AC2017

A dissertation submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfillment of the requirements for the degree of Doctor of Philosophy in Engineering, October 2017 / The dwindling fossil reserves coupled with environmental pollution necessitate the search for clean and sustainable energy resources. Biohydrogen is emerging as a suitable alternative to fossil fuels and has received considerable attention in recent years due to its economic, social, and environmental benefits. However, the industrial application of biohydrogen has been hindered by low yield. Therefore, development of novel techniques to enhance the yield is of immense importance towards large-scale production of biohydrogen. Thus, this research effort explored various options to enhance the yield of biohydrogen during dark fermentation process. Some options explored included (i) the utilization of feedstocks from the agricultural, industrial and municipal sectors, (ii) parametric optimization of biohydrogen production, (iii) investigation of biohydrogen production using metal ions and nitrogen gas sparging, and (iv) assessing the feasibility of biohydrogen scale-up study to pave the way for pilot-scale development. Solid biowaste feedstocks consisting of apple, bread, brewery residue, cabbage, corn-cob, mango, mealie-pap, pear, potato, and sugarcane were investigated for dark fermentative biohydrogen production using anaerobic mixed sludge. The experimental results showed that substrates which are rich in carbohydrates are suitable for dark fermentative biohydrogen-producing bacteria. Consequently, a maximum biohydrogen fraction of 43.98, 40.32 and 38.12% with a corresponding cumulative biohydrogen yield of 278.36, 238.32 and 215.69 mL H2/g total volatile solids (TVS) was obtained using potato, cabbage, and brewery wastes, respectively. Based on these results, potato waste was chosen as a suitable substrate for subsequent biohydrogen production studies. Parametric optimization was carried out on biohydrogen production via dark fermentation using potato waste as the substrate. Effects of operating variables such as pH, temperature, fermentation time, and substrate concentration were investigated via response surface methodology (RSM) approach using a two-level-four factor (24) central composite design (CCD). The obtained predictive model (statistical model) was used to explain the main and interaction effects of the considered variables on biohydrogen production. In addition, the model was employed in the optimization of the operating conditions. Consequently, a secondorder polynomial regression with a coefficient of determination (R2) of 0.99 was obtained and used in the explanation and optimization of operating variables. The optimum operating conditions for biohydrogen production were 39.56 g/L, 5.56, 37.87 oC and 82.58 h for potato waste concentration, pH, temperature and fermentation time, respectively, with a corresponding biohydrogen yield of 68.54 mL H2/g TVS. These results were then validated experimentally and a high biohydrogen yield of 79.43 mL H2/g TVS indicating a 15.9% increase was obtained. Furthermore, the optimized fermentation conditions were applied in the scale-up study of biohydrogen production that employed anaerobic mixed bacteria (sludge) which was immobilized in calcium alginate beads. A biohydrogen fraction of 56.38% with a concomitant yield of 298.11 mL H2/g TVS was achieved from the scale-up study. The research also investigated the influence of metal ions (Fe2+, Ca2+, Mg2+ and Ni2+) on biohydrogen production from suspended and immobilized cells of anaerobic mixed sludge using the established optimal operating conditions. A maximum biohydrogen fraction of 45.21% and a corresponding yield of 292.8 mL H2/g TVS was achieved in fermentation using Fe2+ (1000 mg/L) and immobilized cells. The yield was 1.3 times higher than that of suspended cultures. The effect of nitrogen gas sparging on biohydrogen conversion efficiency (via suspended and immobilized cells) was studied as well. Cell immobilization and nitrogen gas sparging were effective for biohydrogen production enhancement. A maximum biohydrogen fraction of 56.98% corresponding to a biohydrogen yield of 294.83 mL H2/g TVS was obtained in a batch process using nitrogen gas sparging with immobilized cultures. The yield was 1.8 and 2.5 times higher than that of nitrogen gas sparged and non-sparged suspended cell system, respectively. Understanding the functional role of microorganisms that actively participate in dark fermentation process could provide in-depth information for the metabolic enhancement of biohydrogen-producing pathways. Therefore, the microbial composition in the fermentation medium of the optimal substrate (potato waste) was examined using PCR-based 16S rRNA approach. Microbial inventory analysis confirmed the presence of Clostridium species which are the dominant biohydrogen-producing bacteria. The results obtained from this research demonstrated the potential of producing biohydrogen using South African solid biowaste effluents. These feedstocks are advantageous in biohydrogen production because they are highly accessible, rich in nutritional content, and cause huge environmental concerns. Furthermore, optimization techniques using these feedstocks will play a pivotal role towards large-scale production of biohydrogen by increasing throughput and reducing the substrate costs which accounts for approximately 60% of the overall costs. The findings from this research also provide a solid basis for further scale-up and techno-economic studies. Such studies are necessary to evaluate the competitiveness of this technology with the traditional processes of hydrogen production. In summary, the findings from this research effort have been communicated to researchers in the area of biohydrogen process development in the form of peer-reviewed international scientific publications and conference proceedings, and could provide a platform for developing an economic biohydrogen scaled-up process. / CK2018

O processamento do café via úmida inclui as etapas de despolpamento, fermentação, lavagem e separação dos grãos, no qual gera-se grande quantidade de resíduos sólidos (casca e polpa) e água residuária. O estudo dos aspectos microbiológicos na produção de hidrogênio a partir de resíduos do processamento do café é pouco explorado, o que torna esse resíduo atrativo e foco de pesquisas. Neste cenário, buscou-se avaliar o potencial uso destes resíduos como substrato e fonte de bactérias e fungos fermentativos para produção de H2. Adicionalmente, estudou-se a homoacetogênese, processo que afeta a produção de H2, uma vez que o H2/CO2 pode ser consumido para a síntese de ácido acético. Para isso, ensaios em reatores em batelada foram conduzidos para seleção da melhor condição de pré-tratamento hidrotérmico (severidade), dos fatores da fermentação (pH, temperatura, agitação, volume do headspace, concentração de bioaumentação do consórcio microbiano, resíduo de polpa e casca, água residuária e extrato de levedura) que afetam a produção de H2 (Planejamento Plackett-Burman) e homoacetogênese (planejamento fracionado 24-1), seguido do delineamento composto central rotacional (DCCR) para otimização da produção de hidrogênio. Verificou-se que a severidade de pré-tratamento hidrotérmico de 3,53 (180 °C, 15 minutos), resultaram no aumento da concentração de açúcares fermentáveis, com baixa concentração de lignina, fenol, furfural e 5-hidroximentil furfural, obtendo valores de potencial máximo de produção de H2 (P) de 1,8 mL H2. Em relação ao efeito dos fatores da fermentação sobre a produção de H2, obteve-se o maior P de 82 mL H2 em pH 7,0, 30 g DQO L-1 de água residuária, 6 g L-1 de polpa e casca, 30 ºC, 50% de headspace, 180 rpm, sem bioaumentação do consórcio microbiano e 2 g L-1 de extrato de levedura. Por outro lado, as condições que conduziram a consumo significativo de H2 por homoacetogênese foram em pH inicial entre 5,5 e 7,5, headspace entre 40 e 60%, concentração de água residuária entre 10 e 30 g DQO L-1 e concentração de casca e polpa entre 3 e 9 g L-1. Em relação às variáveis estatisticamente significativas (pH, concentração de polpa e casca e volume do headspace), as condições operacionais ótimas para obtenção de P de 240 mL H2, estimadas via planejamento DCCR, foram em pH 7,0, concentração de polpa e casca 7 g L-1 e volume de headspace 30%. No consórcio microbiano, houve predominância de bactérias semelhantes a Lactobacillus sp. e Clostridium sp. e de fungos semelhantes a Saccharomyces sp. e Kazachstania sp. Tais microrganismos foram associados a produção de ácido lático, H2, etanol e ácido acético nos reatores, identificando genes relacionados a enzimas para a degradação de lignina, fenol, celulose, hemicelulose e pectina. Observou-se alta abundância relativa de Clostridium sp. tanto nos ensaios de produção de H2 quanto nos ensaios com consumo de hidrogênio, sendo seus genes associados a homoacetogênese, produção de ácido propiônico e butanol. / Wet coffee processing includes pulping, fermentation, washing and grain separation, in which large amounts of solid waste (husk and pulp) and wastewater are generated. The study of microbiological aspects in the hydrogen production from coffee waste was little explored, which makes this residue attractive and the focus of research. In this scenario, we evaluate the potential use of coffee waste as substrate and source of fermentative bacteria and fungi for H2 production. In addition, homoacetogenesis, a process, that negatively affects H2 production, was studied since H2/CO2 can be consumed for acetic acid production. Assays in batch reactors were conducted to select the best hydrothermal pretreatment condition (severity), fermentation factors affecting the H2 production (pH, temperature, agitation, headspace, bioaugmentation of microbial consortium, concentration of pulp and husk, wastewater and yeast extract) (Plackett and Burman design) and homoacetogenesis (fractional factorial design 24-1), followed by the Rotational Central Composite Design (RCCD) to optimize the H2 production. It was verified that the hydrothermal pretreatment severity of 3,53 (180 °C, 15 minutes), resulted in the increase of fermentable sugars, with low concentration of lignin, phenol, furfural and 5-hydroxyximethyl furfural, obtaining values of the maximum H2 production potential (P) of 1,8 mL H2. The fermentation factors conducing to highest P of 82 mL H2 were pH 7,0, wastewater 30 g COD L-1, 6 g L-1 pulp and husk, 30 °C, 50% headspace, 180 rpm, without bioaugmentation of the microbial consortium and 2 g L-1 yeast extract. On the other hand, the conditions leading to significant H2 consumption by homoacetogenesis were initial pH between 5,5 and 7,5, headspace between 40 and 60%, wastewater concentration between 10 and 30 g COD L-1 and concentration of husk and pulp between 3 and 9 g L-1. In relation to the fermentation factors statistically significant in the H2 production (pH, pulp and husk concentration and headspace), the optimal operational conditions to obtain P of 240 mL H2, estimated through RCCD design, were at pH 7,0, 7 g L-1 pulp and husk concentration and 30% headspace volume. In the microbial consortium, there was a predominance of bacteria similar to Lactobacillus sp. and Clostridium sp. and fungi similar to Saccharomyces sp. and Kazachstania sp. These microorganisms were associated with the production of H2, lactic acid, ethanol and acetic acid in the reactors, identifying genes related to enzymes for the degradation of lignin, phenol, cellulose, hemicellulose and pectin. There was a high relative abundance of Clostridium sp. both in the H2 production assays and in the H2 consumption assays, with genes associated to homoacetogenesis, production of propionic acid and butanol.

A química limpa tem como principal objetivo o desenvolvimento e a implementação de processos e produtos químicos para reduzir ou eliminar o uso ou a geração de substâncias nocivas à saúde humana e ao meio ambiente. Neste trabalho, foram desenvolvidos procedimentos analíticos limpos para a determinação de nitrato e nitrito em águas naturais e para o tratamento dos resíduos gerados na determinação espectrofotométrica de nitrito e fenóis. Para tanto, foram exploradas as principais estratégias empregadas em química limpa: substituição dos reagentes tóxicos, minimização do consumo dos reagentes e dos resíduos gerados e tratamento desses resíduos. O procedimento analítico limpo para a determinação de nitrato em águas naturais foi baseado em medidas diretas no ultravioleta, após separação de nitrato dos interferentes utilizando um sistema de análises em fluxo com coluna de resina aniônica. O método desenvolvido emprega um único reagente (HClO4) em quantidades mínimas (18 µL/determinação) e permite a determinação de nitrato entre 0,50 e 25,0 mg L-1, sem interferência de ácido húmico, NO2-, PO43-, Cl-, SO42- e ferro(III) nas quantidades usuais em águas naturais. A freqüência de amostragem e o coeficiente de variação (n = 20) foram estimados em 17 determinações h-1 e 0,7%, respectivamente. Os resultados obtidos para amostras de águas de diferentes procedências foram concordantes com o método de referência (redução a nitrito por limalhas de cádmio cobreado seguida por reação de diazo-acoplamento) a nível de confiança de 95%. O tratamento do resíduo gerado na determinação de nitrito, empregando irradiação (UV) na presença do reagente de Fenton (80 mmol/L H2O2 e 1 mmol/L Fe2+), promoveu completa descoloração do resíduo com diminuição de ca. 87% na concentração de carbono orgânico total. A fotodegradação também foi aplicada no tratamento do resíduo gerado na determinação de fenóis totais com 4-aminoantipirina. A degradação ocorreu na presença de H2O2 e irradiação (UV). A completa supressão da absorção de radiação pela 4-aminoantipirina foi observada após 30 min de recirculação da solução no foto-reator, à vazão de 4 mL/min. O procedimento analítico para a determinação de nitrito foi baseado em sistema de análises em fluxo com multicomutação empregando mini-bombas solenóides para o gerenciamento das soluções. O sistema foi acoplado a um foto-reator para a degradação em linha dos resíduos gerados. O método desenvolvido minimiza as quantidades de reagentes (0,6 mg sulfanilamida e 0,03 mg N-naftil-etilenodiamina por determinação) e permite a determinação de nitrito entre 0,10 e 1,00 mg L-1 (r = 0,998) com sensibilidade comparável à alcançada no procedimento com adição contínua de reagentes. O limite de detecção (99,7% de confiança), coeficiente de variação (n = 20) e freqüência de amostragem foram estimados em 17 µg L-1, 2,6% e 80 determinações h-1, respectivamente. / Green chemistry has as principal objective the development and implementation of chemical processes and products to minimize or eliminate the use or generation of harmful substances to the human health and the environment. In this work, clean analytical procedures for determination of nitrate and nitrite in natural waters and for the treatment of wastes generated in the spectrophotometric determination of nitrite and phenol were developed. The principal strategies employed in green chemistry were explored to achieve these goals: replacement of the toxic reagents, minimization of reagent consumption and waste generation and waste treatment. The clean analytical procedure for nitrate determination in natural waters was based on the direct spectrophotometric measurement in the ultraviolet, after separation of nitrate from interfering species in a flow-injection system with an anion-exchange resin. The developed method employ only one reagent (HClO4) in minimum amount (18 µL/determination) and can be applied for nitrate determination within 0.50 and 25.0 mg L-1, without interference of humic acid, NO2-, PO43-, Cl-, SO42- and iron(III) in concentrations typically found in natural waters. The sampling rate and the coefficient of variation (n = 20) were estimated as 17 determinations per hour and 0.7%, respectively. Results obtained for natural water samples of different origin were in agreement with the reference method (reduction to nitrite by copperized cadmium filings followed by a diazo-coupling reaction) at the 95% confidence level. The treatment of the waste generated in nitrite determination employing UV irradiation in the presence of Fenton reagent (80 mmol/L H2O2 and 1 mmol/L Fe2+) caused the complete discoloration of the waste and reduced the total organic carbon concentration in 87%. The photodegradation was also applied for the treatment of the waste generated in the determination of total phenols with 4-aminoantipyrine. The degradation occurred in the presence of H2O2 and UV irradiation. Radiation absorption by 4-aminoantipyrine was completely suppressed after 30 min of treatment of solution in the recirculation mode at 4mL/min. The analytical procedure for nitrite determination was based on a flow system with multicommutation employing solenoid micro-pumps for the solution handling. The developed method minimizes the reagent amounts (0.6 mg sulfanilamide and 0.03 mg N-(1-Naphthyl)-ethylene-diamine per determination) and can be applied for nitrite determination within 0.10 and 1.00 mg L-1 (r = 0.998) with sensitivity comparable to the achieved in the procedure with continuous reagent addition. The detection limit (99.7% of confidence), coefficient of variation (n = 20) and sampling rate were estimated as 17 µg L-1, 2.6% and 80 determinations per hour, respectively.