Hexachloro-1,3-butadiene (HCBD) is a toxic aliphatic chlorinated hydrocarbon which is widely used as a fungicide, herbicide and heat transformer fluid. HCBD is resistant to microbial degradation and, therefore, persists in aquatic and soil environments worldwide. In this thesis, the ability of non-specific bacteria from various sources to dechlorinate HCBD in the presence of either acetate or lactate (as an electron donor) and cyanocobalamin (as an electron shuttle) under different conditions was investigated. Cultivating specific populations to reduce cyanocobalamin as a method to increase HCBD dechlorination rate was investigated. Also, the factors responsible for HCBD dechlorination and the stalling of dechlorination were studied. Lastly, redox potential measurement during the microbial reductive dechlorination of HCBD for online detection of ongoing dechlorination was evaluated. Findings from the Project „« Non-specific bacteria from activated sludge, anaerobic digested effluent from municipal waste, piggery waste and sheep rumen content are able to dechlorinate HCBD in the presence of cyanocobalamin to chlorine-free C4 gases in a biochemical reaction. „« Dechlorination was equated to the formation of completely dechlorinated end-products from HCBD dechlorination. „« Methanogens were found to be involved in HCBD dechlorination. „« Mediators rather than specific bacteria were responsible for the fast dechlorination rates. Results suggest that activated sludge may release synthesized mediators into the supernatant to enable enhanced HCBD dechlorination. „« HCBD dechlorination can be monitored using oxidation reduction potential (ORP). ORP has an effect on HCBD dechlorination rate. Scientific Significance/Novelty The most significant finding from this research is that it demonstrates chlorine-free end-products in contrast with other studies in literature (Booker and Pavlosthasis, 2000; Bosma et al., 1994) where dechlorination was equated with disappearance of HCBD into bacterial biomass and the detection of partially dechlorinated gases such as trichlorobutadiene. It also shows that, in contrast to literature where specific bacteria (i.e., pure strains/cultures) were commonly used for the dechlorination of polychlorinated hydrocarbons, results from this thesis show that non-specific bacteria were able to dechlorinate HCBD in the presence of cyanocobalamin at ratesƒx sufficiently high to be considered for bioremediation projects. Moreover, results demonstrate that ORP can be used to monitor HCBD dechlorination.

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Le manque de compréhension des réactions liées à l'utilisation de l'ozone a constitué un clair frein au développement de séquences de blanchiment non-chlorées efficaces. Considéré comme un élément central des séquences TCF face aux séquences ECF comprenant du dioxyde de chlore, l'ozone ne permettait pas l'obtention de pâtes cellulosiques de qualité aussi élevée. Le but de ce travail est l'élaboration de séquences de blanchiment non-chlorées permettant l'obtention d'un produit final de haute qualité. Ce type de séquence pourrait présenter de nombreux avantages, parmi lesquels sont envisagés des gains environnementaux indéniables. Afin d'atteindre cet objectif, les réactions liées à l'ozone et au peroxyde d'hydrogène ont été étudiées plus avant. Après une revue bibliographique, cet écrit revient dans un second chapitre sur certaines hypothèses de la littérature qui, confrontées entre elles et avec certains premiers résultats, permettent de mettre en évidence certaines incohérences. Dans une troisième partie, plusieurs pâtes de compositions différentes ont été étudiées, afin de vérifier l'ordre des réactions de l'ozone sur les divers composés d'une pâte kraft, et afin également d'envisager l'ampleur des dégradations subies par la cellulose dans ces différents substrats, qu'il s'agisse de dépolymérisation, ou de modifications fonctionnelles. Ces résultats ont permis de formuler une hypothèse relative aux réactions de l'ozone sur des composés insaturés, tels que ceux des acides hexenuroniques. Par l'utilisation d'une méthode de détection rarement utilisée en papeterie, cette hypothèse a été validée : la réaction de l'ozone sur certains composés insaturés non-aromatiques pourrait générer des radicaux, eux-mêmes à l'origine de mécanismes de modification de la cellulose. D'après les résultats, l'ozone ne serait que marginalement directement responsable des dégradations de la cellulose. L'effet des différents stades alcalin a également été envisagé dans une quatrième partie. C'est ainsi que la dépolymérisation de la cellulose et ses modifications fonctionnelles ont également été analysées à l'issue de ces stades. Les résultats suggèrent notamment l'existence d'un mécanisme de dépolymérisation impliquant les carbonyles cellulosiques et des agents nucléophiles. Une grande partie de la dégradation se produisant dans les stades au peroxyde d'hydrogène lui serait ainsi imputable. Le dernier chapitre revient sur ces différentes considérations, dans l'optique de minimiser les inconvénients liés à ces différents stades, et particulièrement aux stades à l'ozone. Différentes combinaisons des réactifs ont été envisagées pour former des séquences non-chlorées. Les résultats montrent que l'obtention de pâtes de qualité comparable à celle de pâtes issues de séquences de blanchiment chlorées est possible. / The lack of understanding regarding the reactions of ozone with pulp components is one of the reasons why chlorine-free bleaching never really developed. Ozone is actually believed to lead to an extensive degradation of cellulose, contrary to the agent it could replace: chlorine dioxide. However, as the use of chlorinated compounds has many drawbacks, including the generation of toxic compounds, non-degrading chlorine-free bleaching sequences have to be designed. To do so, a better understanding of reactions involving ozone and hydrogen peroxide has to be gained. The first part of this very work consisted of a literature review. In the second part, some of the main hypotheses extracted from the literature were compared with other elements and first results, to show they inevitably led to contradictions and that new theories were needed. The third part was dedicated to ozone. The order of its reactions with pulp components was first of all checked. The properties of pulps of various compositions were then measured through ozonations. This study led to a new hypothesis, which was validated thanks to ESR spectroscopy. The reaction of ozone with some non-aromatic unsaturated compounds seems to give radical species. Those radical species would be in turn responsible for the depolymerization of cellulose, and the formation of carbonyl groups on cellulose as well. The fourth part dealt with the impact of alkaline treatment on cellulose after ozonations. Observations about carbonyl content and degree of polymerization suggest a new mechanism related to carbonyl and nucleophilic agents, explaining a main part of the depolymerization undergone by the cellulose. The last chapter of this work summarizes the trials regarding the optimisation of a chlorine-free bleaching sequence. It proves that high-quality pulps can be obtained by chlorine-free processes.

Submitted by Rafael dos Santos (rafasantos01@hotmail.com) on 2017-07-11T13:22:05Z No. of bitstreams: 1 Tese_AVALIAÇÃO TÉCNICO-ECONÔMICA DO BRANQUEAMENTO SEGUNDO A SEQUÊNCIA ADP_VERSÃO FINAL.pdf: 2700905 bytes, checksum: 60e71eaa2391df1196b6055786ca2bd3 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-07-14T13:32:07Z (GMT) No. of bitstreams: 1 santos_r_dr_guara.pdf: 2700905 bytes, checksum: 60e71eaa2391df1196b6055786ca2bd3 (MD5) / Made available in DSpace on 2017-07-14T13:32:07Z (GMT). No. of bitstreams: 1 santos_r_dr_guara.pdf: 2700905 bytes, checksum: 60e71eaa2391df1196b6055786ca2bd3 (MD5) Previous issue date: 2017-06-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Diferentes sequências e condições de branqueamento têm sido exploradas ao longo dos últimos anos, nos quais o processo em múltiplos estágios tornou-se prática comum nas indústrias. A produção de celulose como um todo é uma atividade industrial que requer alto investimento e produz grande impacto ambiental. Sendo assim, alternativas que auxiliem na sua realização de forma socialmente responsável, economicamente viável e ambientalmente correta são de grande interesse. Este estudo teve como objetivo avaliar a viabilidade técnicoeconômica de uma nova sequência de branqueamento sob condições diferenciadas, em relação às comumente empregadas nas empresas do setor de celulose e papel. Para tanto, uma sequência de branqueamento utilizada em uma indústria do setor foi tomada como referência, sendo os estudos a priori conduzidos em laboratório com finalidade de ser possivelmente implementados em escala industrial. Os estágios que compõem a sequência proposta neste estudo são uma hidrólise ácida a quente (AHT), uma dioxidação (D) e uma peroxidação (P), ao passo que os estágios que compõem a sequência referência são uma hidrólise ácida a quente seguida de dioxidação (AHT/D), uma extração alcalina oxidativa com peróxido de hidrogênio (E+P) e uma dioxidação (D). Os branqueamentos foram conduzidos baseados nas condições industriais praticadas pela empresa parceira, bem como pelas condições descritas pela sequência proposta. Foram utilizadas as técnicas de valor presente líquido e payback como ferramentas de auxílio à tomada de decisão para a análise de viabilidade econômica. Os resultados obtidos mostraram a potencialidade do uso da tecnologia de branqueamento ADP, uma vez que a sequência descrita por esta tecnologia produziu polpa branqueada de qualidade similar à obtida pela sequência referência. A sequência proposta mostrou-se ainda mais econômica, principalmente no que tange a demanda por dióxido de cloro, principal reagente utilizado em fábricas que trabalham sob a premissa de branqueamento livre de cloro elementar (ECF). A polpa branqueada pela sequência ADP apresentou melhores resultados quanto à estabilidade da alvura do que a polpa branqueada pela sequência AHT/D(E+P)D. Do ponto de vista econômico, a implementação desta nova tecnologia de branqueamento em três estágios a nível industrial é completamente viável, sendo os seus resultados de viabilidade econômica destacadamente favoráveis à sua utilização. / Different bleaching sequences and conditions have been explored along the last years, in which the process in multiple stages has become common practice at the mills. The pulp production is an industrial activity that requires high investments and promotes a great environmental impact. Hence, alternatives which help its accomplishment in a responsible social way, economically feasible and environmentally correct are quite desirable. This study aimed to evaluate the technical-economic feasibility of a novel bleaching sequence under differential conditions, in relation to those commonly applied in pulp and paper mills. Therefore, a bleaching sequence used in a mill has been taken as reference, being the studies a priori carried out in laboratory with the intention of being possibly implemented in industrial scale. The stages that make part of the sequence proposed in this study are hot acidic hydrolysis (AHT), dioxide stage (D) and peroxide stage (P), while the stages that make part of the reference sequence are hot acidic hydrolysis followed by a dioxide stage (AHT/D), oxidative alkaline extraction with hydrogen peroxide (E+P) and a dioxide stage (D). The bleaching processes were carried out based on industrial conditions practiced by the partner company, as well as by the conditions described by the proposed sequence. Net present value and payback techniques were used as making-decision supporting tools in the economic feasibility analysis. The obtained results show the potentiality of the ADP bleaching technology usage, once the sequence described by this technology produced bleached pulp of similar quality to the reference sequence. The proposed sequence is also more economic, mainly regarding the chlorine dioxide demand, the main reagent used in mills that work under the premise of elemental chlorine free (ECF) bleaching. Pulp bleached by ADP sequence presented better results regarding brightness stability than pulp bleached by A/D(E+P)D sequence. Over economic point of view, the implementation of this novel bleaching technology in three stages at industrial level is completely feasible, being its results of economic feasibility quite favorable to its utilization.