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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Influência da estratégia de alimentação no desempenho do reator anaeróbio em batelada seqüencial contendo biomassa imobilizada / Influence of feeding strategy on the performance of anaerobic sequencing batch reactor containing immobilized biomass

Alisson Carraro Borges 07 April 2003 (has links)
Submeteu-se um reator anaeróbio operado em batelada seqüencial a diferentes tempos de enchimento, com o objetivo de verificar-se o desempenho do sistema. O reator, construído em acrílico e com capacidade de 6,3 L, tratou por ciclo um volume de 2,5 L de esgoto sintético com concentração de aproximadamente 500 mgDQO/L. O sistema foi operado à temperatura de 30 graus mais ou menos 1, com duração de 8 h para cada ciclo (tC) e agitação de 500 rpm implementada mecanicamente. Cubos de espuma de poliuretano foram usados como suporte para imobilização da biomassa. No início de cada ciclo, o reator foi carregado com 60 % do volume do esgoto; o restante foi preenchido durante tempos de enchimento (tF) que caracterizaram as diferentes estratégias de alimentação. Os resultados obtidos demonstram que para razões tF/tC <= 0,5 o sistema alcança médias de remoção de matéria orgânica acima de 75 % e 70% para amostras filtradas e não filtradas, respectivamente. Nos ensaios em que tF/tC > 0,5, registrou-se perda na eficiência e formação de polímeros extracelulares, apesar da estabilidade observada. O estudo contribuiu para o melhor entendimento do sistema e definição de técnicas de operação em futuras aplicações. / An anaerobic sequencing batch reactor was operated at different fill times with the objective to asses system performance. The reactor, made of plexiglas and with a capacity of 6.3 L, treated per cycle 2.5 L of synthetic wastewater with a concentration of nearly 500 mgCOD/L. The system was operated at a temperature of 30oC, with 8-h cycles (tC) and mechanical agitation rate of 500 rpm. Cubic particles of polyurethane foam were used as support material for anaerobic biomass immobilization. At the start of each cycle, the reactor was fed with 60 % of the wastewater volume, the remainder was filled at different feeding times (tF) that characterized the different feeding strategies. The results obtained showed that for a ratio of tF/tC <= 0.5 the system attained average filtered and non-filtered substrate removal efficiency of 75 % and 70 %, respectively. Ratios of tF/tC > 0.5, resulted in loss in efficiency and formation of extra cellular polymers, in spite of system stability. The study contributed to a better understanding of the system and definition of operational techniques for future applications.
12

Tratamento de esgoto sanitário em reatores anaeróbios operados em bateladas seqüenciais e periodicamente aerados / Treatment of domestic sewage in periodically aerated anaerobic sequencing batch reactors

Francisco José Vela 17 March 2006 (has links)
O avanço da tecnologia anaeróbia para tratamento de esgotos deve ser creditado em grande parte ao desenvolvimento dos modernos reatores de alta taxa de aplicação orgânica, com os maiores méritos ao filtro anaeróbio ascendente e principalmente, à configuração do UASB. A evolução dos reatores levou à busca para maximizar a aplicação prática para aproveitar todas as potencialidades dos processos anaeróbios. Todas as modernas configurações têm em comum a preocupação em atender requisitos essenciais em um reator: formação e retenção de grande quantidade de biomassa e melhoria do contato biomassa/matéria orgânica. Esta pesquisa tem como principal objetivo avaliar dois reatores anaeróbios, operados em batelada seqüencial e periodicamente aerados, como unidade de tratamento das águas residuárias geradas no campus da Universidade de São Paulo em São Carlos. Um dos reatores contém biomassa imobilizada em espuma de poliuretano e o outro é operado com biomassa suspensa ou auto-imobilizada, sem utilização de suporte inerte. Os sistemas, na primeira etapa operacional, anaeróbia, apresentaram remoção de matéria orgânica, com eficiências médias para espuma de 61% (ASBBR) e grânulos de 56% (ASBR) e eficiências na remoção de sólidos iguais a 62% de SST e 65% de SSV no ASBBR e 56 % de SST e 61% de SSV no ASBR. Na segunda etapa operacional, anaeróbia e aeróbia, os reatores ASBR e ASBBR, mostrou que a estratégia de operação com etapa anaeróbia seguida por período com aeração não foi adequada para remoções de matéria orgânica e nitrogênio. Os reatores operaram com grande instabilidade e baixas eficiências de remoção de matéria orgânica, abaixo das observadas em reator operado de forma anaeróbia. / The advance of anaerobic technology for wastewater treatment should be credited in great part to the development of the modern reactors with high rates of organic application, with merit to the ascendant anaerobic filter and mainly to the UASB configuration. The evolution of reactors led to the search to maximize the practical aplication to make the best use of all the potentialities of the anaerobic processes. All the modern configurations have in common the preoccupation to deal with essential requisites in a reactor: formation and retention of a large quantity of biomass and improvement in the biomass/organic matter contact. This research prime objective is to evaluate two anaerobic reactors, operated in sequential batch and periodically aerated, as unity of treatment of wastewaters generated at the campus of the University of São Paulo in São Carlos. One of the reactors contains biomass immobilized on polyurethane foam and the other is operated with suspended or autoimmobilized biomass, without the use of inert support. The systems, in the first operational step, anaerobic, presented organic matter removal, with medium efficiencies for foam of 61% (ASBBR) and granule of 56% (ASBR) and efficiencies in the removal of solids equal to 62% of TSS and to 65% of VSS in the ASBBR and to 56% of TSS and to 61% of VSS in the ASBR. In the second operational step, anaerobic and aerobic, the ASBBR and ASBR reactors showed that the strategy of operation with anaerobic step followed by a period with aeration was not adequate for the removal of organic matter and nitrogen. The reactors operated with great instability and low efficiency of organic matter removal, with results below of the ones observed in a reactor operated in the anaerobic way.
13

Estudo da diversidade microbiana em reator ASBR no tratamento da drenagem ácida de minas sintética sob diferentes condições operacionais

BELI, Euzebio 12 November 2014 (has links)
Neste trabalho foi realizada a caracterização microbiana, por meio de técnicas de Biologia Molecular, do lodo granular do processo de precipitação dos metais ferro, zinco e cobre por sulfeto gerado a partir de um reator biológico em batelada sequencial (ASBR) para redução de sulfato de drenagem ácida de minas (DAM) sintética em suas diferentes fases operacionais. O reator foi inoculado com lodo granular de reator UASB tratando efluente de abatedouro de aves, operando em relação DQO/sulfato 1,0. O etanol foi utilizado como doador de elétrons e o sulfato de sódio como receptor de elétrons. Para o presente estudo as amostragens de lodo foram realizadas em pH 5,0; pH 4,0; pH 4,0 + Fe2+, pH 4,0 + Fe2+; Zn2+; pH 4,0+Fe2+; Zn2+; Cu2+ sempre quando ocorria redução máxima de sulfato no reator, o inóculo também foi estudado para comparação. Após coleta de todas as amostras, realizou-se a extração do DNA, seguida de purificação e amplificação para o RNAr16S para os Domínios estudados e as sequencias foram separadas através de DGGE. A estrutura das comunidades foi analisada em função da composição e riqueza de bandas de DGGE nos consórcios microbianos. A análise do perfil de bandas do DGGE permitiu visualização da dinâmica da população microbiana presente em cada fase do tratamento biológico da DAM. Os resultados revelaram que ocorreu maior variação na diversidade de microrganismos do domínio Bacteria do que de Archaea nos tratamentos da DAM com os parâmetros operacionais estudados. Dentre essas observações, percebe-se que as sucessivas diminuições de pH foram menos influentes na diversidade do que foi a adição dos metais, principalmente quando houve adição do Fe. O Domínio Bacteria apresentou maiores reduções de bandas do que o domínio Archaea, que sofreu menores influências às condições operacionais. Comparando-se a diversidade de bactérias e arqueias neste estudo, observa-se que as bactérias foram 56,5% maior que as arqueias em termos de diversidade pelas bandas de DGGE apresentadas. Diminuições no pH e adição sucessiva dos metais Fe, Zn e Cu foram associados a alterações temporais na estrutura da comunidade bacteriana. Nas análises de sequenciamento para domínio Bacteria, apesar de baixa qualidade do sequenciamento das bandas recortadas, foi possível fazer uma comparação entre o BLAST e a base de sequências do NCBI. Uma das bandas apresentou similaridade de 88 e 87% com clones não cultivados de Geobacter e Clostridum, respectivamente. Estes microrganismos são relatados como sendo redutores de sulfato. Outras duas bandas apresentaram 91% de similaridade com clone não cultivado de bactérias. Já para o Domínio Archaea, a análise comparativa indicou similaridade de três das cinco bandas com os clones não cultivados de Methanomicrobiales archaeon F5OHPNU07IK8FO e duas das bandas com o gênero Methanosaeta sp. clone DI CO3, ambas arqueias relatadas como sendo presentes em lodo granular de diversos tratamentos anaeróbios. Conclui-se que a estimativa da diversidade permitiu inferir que as alterações nas composições das comunidades microbianas foram devidas as condições operacionais impostas. / The microbial characterization of this study was carried out by molecular biology techniques, of granular sludge samples from precipitation of the metals iron, zinc and copper in sulphide generated from a biological sequencing batch reactor (ASBR) to reduce the sulphate of synthetic acid drainage mines in its different operational phases. The reactor was inoculated with granular sludge from UASB reactor treating effluent from poultry slaughterhouse operating in ratio COD/sulphate 1.0. Ethanol was used as electron donor and sodium sulphate as electron acceptor. For this study, samples of sludge were taken on pH 5.0; pH 4.0; pH 4.0 + Fe2+, pH 4.0 + Fe2+; Zn2+; pH 4.0 + Fe2+; Zn2+; Cu2+ whenever maximum reduction of sulphate in the reactor occurred. The inoculums was also studied for comparison. After collecting all samples, the extraction of DNA was carried out, followed by purification and amplification to RNAr16S for the studied Domains and the sequences were separated by DGGE. The structure of the communities was analyzed in view of the composition and richness of DGGE bands in microbial consortia. The DGGE bands’ profile analysis allowed visualization of the dynamics of the microbial population present in each phases of the AMD biological treatment. Results showed that a higher variation occurred in diversity of microorganisms of the Bacteria domain than that in Archaea in treatment with the operating parameters studied. Among these observations, it is perceived that the successive decreases in pH were less influential in diversity than it was the metals additions, mainly when there was addition of Fe. The Bacteria domain presented higher reductions bands than the Archaea domain, which suffered lower influences from operational conditions. When comparing the diversity of Bacteria and Archaea in this study, it is observed that the bacteria were 56.5% higher than the Archaea in terms of diversity by DGGE bands presented. Diminishing in pH and successive addition of the metals Fe, Zn and Cu were associated with temporal changes in the structure of bacterial community. In sequencing analysis to Bacteria domain, although the low quality of the sequence of the cut bands, it was possible to make a comparison between BLAST and the base of sequence of the NCBI. One of the bands presented a similarity of 88% and 87 with uncultivated clones of Clostridum and Geobacter, respectively. These microorganisms are reported to be sulphate reducers. Two other bands presented 91% similarity with the uncultivated clone of bacteria. For the Archaea domain the comparative analysis indicated similarity of three of the five bands with the uncultivated clones of archaeon Methanomicrobiales F5OHPNU07IK8FO and two of the bands with the genus Methanosaeta sp. clone DI CO3, both of then reported as present in granular sludge of several anaerobic treatments. It is concluded that the estimate of diversity allowed inferring that the alterations in the composition of microbial communities occurred due the imposed operations conditions.
14

Performance Comparison of EIGRP/ IS-IS and OSPF/ IS-IS / Performance Comparison of EIGRP/ IS-IS and OSPF/ IS-IS

Lemma, Esuendale Shewandagn, Hussain, Syed Athar, Anjelo, Wendwossen Worku January 2010 (has links)
In modern communication networks, routing protocols are used to determine the shortest path to the destination. Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP) and Intermediate System to Intermediate System (IS-IS) are the dominant interior routing protocols for such networks. This thesis presents a simulation based analysis of these protocols. We used the combination of EIGRP&amp;IS-IS, OSPF&amp;IS-IS routing protocols on the same network in order to reveal the advantage of one over the other as well as the robustness of each protocol combination and how this is measured. To carry out the network simulations, we used Optimized Network Engineering Tool (OPNET). The comparison analysis is based on several parameters that determine the robustness of these protocols. The routing protocol convergence time is one important parameter which determines the time needed by the routers to learn the new topology of the network whenever a change occurs in the network. The routing protocol which converges faster is considered a better routing protocol. Point-to-point link throughput, HTTP object response time, database response time and e-mail download response time are other parameters we used to measure the routing performance of the network. / I moderna kommunikationsnät, är routingprotokoll används för att bestämma den kortaste vägen till destinationen. Open Shortest Path First (OSPF), Enhanced Interior Gateway Routing Protocol (EIGRP) och Intermediate System till Intermediate System (IS-IS) är den dominerande interiören routingprotokoll för sådana nät. Denna avhandling presenterar en simulering baserad analys av dessa protokoll. Vi använde en kombination av EIGRP &amp; IS-IS, IS OSPF &amp;-IS routingprotokoll i samma nätverk i syfte att avslöja fördel ovanpå varandra samt robustheten i varje protokoll kombination och hur detta mäts. Att utföra nät simuleringar har vi använt Optimerad Network Engineering Tool (OPNET). Jämförelsen Analysen bygger på flera parametrar som avgör hur starka dessa protokoll. De routingprotokoll konvergens tid är en viktig parameter som bestämmer den tid som krävs av routrar för att lära sig nya topologi i nätverket snart en ändring sker i nätet. Routing-protokoll som konvergerar snabbare anses vara en bättre routing protokoll. Punkt-till-punkt länk genomströmning, HTTP objekt svarstid, databas responstid och e-post nedladdning responstid är andra parametrar som vi använde för att mäta routing nätverkets prestanda. / Esuendale- +46738790290 Syed- +46738957792 Wendwossen +46738956203
15

Treatment of typical South African milking parlour wastewater by means of anaerobic sequencing batch reactor technology.

Du Preez, Jeanne 03 1900 (has links)
Thesis (MScEng (Process Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Due to the growing demands for fresh and clean water, the investigation into the treatment, reuse and recycling of wastewater from all industries are becoming more of a priority, both globally and in South Africa where as much as 62 % of the total water used per year is used by the agricultural sector. The investigation into the recycling and reuse of wastewater in the agricultural sector (especially the dairy farming industry) is therefore no exception. The water usage in five typical South African milking parlours was estimated in this study and ranged from 15 to 51 L.cow-1.day-1. However, the water used for the cleaning in place (CIP) washing of the milking equipment were rather similar in all five milking parlours and ranged between 4.9 and 6.4 L.cow-1.day-1. The possibility of handling and treating the CIP wastewater separately from the rest of the milking parlour wastewater has been considered in the past by other researchers. Anaerobic digestion, as a means of treating wastewater from the dairy industry, has been employed successfully in both full scale and laboratory scale projects. The wastewater from equipment washing of milking parlours is assumed to have similar characteristic to that generated from dairy factories. The anaerobic sequencing batch reactor (ASBR) system is gaining popularity as a wastewater treatment technology lately due to its simplicity, ease of operation and compact design and is therefore expected to be a suitable and practical solution for dairy farmers in treating milking parlour wastewater from equipment washing. Investigation into anaerobic treatment at lower temperatures than the conventional mesophilic range is also becoming of interest due to lower energy requirements. The aim of this study was to determine whether the ASBR technology could be considered as a suitable technology for treating wastewater from the CIP washing of milking parlour equipment. To support this study, the water usage and CIP effluent generated at typical South African milking parlours were firstly verified. Subsequently, laboratory work entailed: • Assessing the sensitivity of the ASBR process (at mesophilic temperature of 35 °C) to fluctuations in the concentration of the detergents in synthetic CIP milking parlour wastewater; and • Evaluating the performance of the ASBR process at 22.5 and 35 °C when treating real wastewater from the CIP washing of milking equipment. Chemical oxygen demand (COD) removal efficiencies between 89 and 98 % were achieved when the synthetic wastewater (similar to wastewater from the CIP washing of milking equipment with COD concentrations ranging between 12 600 and 13 400 mg.L-1) was treated in an ASBR. The results showed that an increase in the CIP detergent concentration up to four times the concentration normally used in milking parlours did not significantly affect the ASBR performance in terms of methane productivity, methane yield and COD removal efficiencies when OLRs between 0.6 and 5.2 g COD.L-1.day-1 were applied. The results also showed that COD removal efficiencies between 92 and 98 % could be achieved in the ASBR process operated at 35 °C when treating real CIP milking parlour effluent (with COD concentrations ranging between 14 900 and 28 800 mg.L-1) when applying OLRs up to 6.6 g COD.L-1.day-1, without nutrient control. Therefore, the ASBR process is suitable to treat real milking parlour wastewater with OLRs above 6 g COD.L-1.day-1 at mesophilic temperatures. At an operating temperature of 22.5 °C, the ASBR achieved TCOD removal efficiencies between 86 and 98 % when treating real CIP effluent. Despite these high COD removal efficiencies, the reactor failed at an OLR of 2.9 g COD.L-1.day-1. As such, the ASBR process appears to be susceptible to failure (due to overloading) when the OLR is increased too rapidly at this low operating temperature. This is most probably due to the fact that methanogenic bacteria do not acclimatise and operate as well at temperatures below the mesophilic range. However, during a second attempt at 22.5 oC, the ASBR achieved COD removal efficiencies between 89 and 97 % when the OLR was increased less rapidly, up to 3.3 g COD.L-1.day-1. These results show that the ASBR process can indeed treat real milking parlour wastewater at 22.5 °C without nutrient control at OLRs above 3 g COD.L-1.day-1. The COD concentration in the effluent from the ASBRs when the maximum OLRs were applied were always below 1 000 mg.L-1. This is notably lower than the South African legal limit for irrigation of up to 50 m3 of wastewater per day. However, this is significantly higher than the South African legal limit of 75 mg.L-1 for safe disposal into a fresh water body. / AFRIKAANSE OPSOMMING: Die wêreldwye toename in die aanvraag na vars, skoon water het tot gevolg dat die ondersoek in die behandeling, hergebruik en herwinning van afvalwater tans groot aandag geniet. Nie net wêreldwyd nie, maar ook in Suid-Afrika waar tans 62 % van die water wat gebruik word per jaar, aangewend word vir die lanbou sektor. Daarom is die ondersoek na besparing van water in lanbou aktiwiteite (veral melkboerderye) geen uitsondering nie. Die watergebruik tydens melktyd in 5 verskillende melkerye is ondersoek en dit blyk dat die watergebruik in die 5 melkery drasties van mekaar verskil. Dit strek van ‘n minimum van 15 litres per koei per dag tot ‘n maksimum van 51 liters per koei per dag. Die volume water wat gebruik word vir die outomatiese was van die melktoerusting het nie so baie gevarieer nie en het gestrek tussen 4.9 en 6.4 liter per koei per dag. Die moontlikheid om die afvalwater wat gegenereer word tydens die outomatiese was van die melktoerusting apart te hou van die res van die afvalwater, is in die verlede deur ander navorsers oorweeg. Afvalwater van suiwelfabrieke is in die verlede al deur middel van anaerobiese vertering in ‘n groot aantal laboratorium- en volskaalse anaerobiese aanlegte behandel. Daar word aangeneem dat die afvalwater wat gegenereer word tydens die was van melktoerusting min of meer dieselfde samestelling sal hê as die afvalwater van suiwelfabrieke. Die anaerobiese opvolgende lot reaktor (AOLR) word al hoe meer gewild in anaerobiesewaterbehandeling as gevolg van die eenvoudige en maklike werking en kompakte ontwerp. Dit word verwag dat hierdie tegnologie ‘n gepaste en praktiese oplossing sal wees om die afvalwater van die was van melktoerusting te behandel. Die anaerobiese behandeling van afvalwater by temperature laer as die normale mesofiliese temperature word ook al hoe meer gewild as gevolg van minder hitte wat benodig word. Die doel van hierdie studie was om te bepaal of die AOLR tegnologie ‘n gepaste tegnologie is om afvalwater wat gegeneer word tydens die outomatiese was proses van melkery toerusting te behandel. Ter ondersteuning van die doel, is die watergebruik in ‘n paar tipiese, Suid- Afrikaanse melkerye eers bevestig. Daaropvolgend, het die laboratoriumwerk die volgende behels: • The bepaal of die AOLR proses (wat by mesofiliese temperatuur van 35 °C bedryf was) sensitief is vir veranderinge in die konsentrasie van sepe in sintetiese waswater wat na ‘n AOLR gevoer word; en • Om die werking van die AOLR proses te ondersoek wanneer regte afvalwater van melkery by onderskeidelik 22.5 en 35 °C behandel word. Chemiese suurstof behoefte (CSB) verwydering van 89 to 98 % is bereik toe sintetiese afvalwater wat gelykstaande aan afvalwater gegenereer tydens die was van melk toerusting is (met CSB konsentrasies tussen 12 600 en 13 400 mg.L-1) in ‘n AOLR behandel is. Die resultate het getoon dat daar geen aanmerklike verskil in die werking van die AOLR in terme van metaanproduksie, metaanopbrengs en CSB verwyderingseffektiwiteit was met a toename tot en met so hoog as vier maal die normale seepkonsentrasie in die afvalwater was toe organiese ladingstempo’s (OLTs) tussen 0.6 en 5.2 g CSB.L-1.dag-1 aangewend was nie. Die resultate het ook getoon dat die CSB van regte afvalwater van melkerye (met CSB konsentrasies tussen 14 900 en 28 800 mg.L-1) met 92 tot 98 % verminder kan word wanneer dit in ‘n AOLR (wat by 35 °C bestuur word) en OLTs tot so hoog as 6.6 g CSB.L-1.dag-1 aangewend word, sonder dat die nutrientinhoud in die afvalwater beheer was. Hierdie AOLR proses wat is dus gepas om afvalwater van melkery te behandel met OLTs bo 6 CSB.L-1.dag-1 by mesofiliese temperature. Die AOLR wat by ‘n temperatuur van 22.5 °C bedryf was, het CSB verwydering tussen 86 en 98 % behaal. Ondanks die hoë CSB verwydering het die reaktor misluk by ‘n maksimum OLT van 2.9 g CSB.L-1.dag-1. Dit het getoon dat die AOLR proses meer geneig is om vatbaar te wees vir mislukking (as gevolg van ‘n oorlading) wanneer die OLT te vinnig verhoog word by laer temperature. Dit is moontlik as gevolg daarvan dat die metanogeniese bakterieë nie so goed aanpas en werk by temperature laer as mesofiliese temperature nie. Nietemin, tydens ‘n tweede probeerslag by 22.5 °C, het die AOLR CSB verwydering tussen 89 en 97 % behaal tydens ‘n stadiger toename in die OLT tot en met 3.3 g CSB.L-1.dag-1. Hierdie resultate dui aan dat die AOLR proses wat by ‘n temperatuur van 22.5 °C bedryf word ook gepas is om afvalwater van melkerye te behandel, sonder nutrient beheer by OLTs hoër as 3 g CSB.L-1.dag-1. Die CSB konsentrasies in die afvloeisel van die AOLR’e in die studie tydens die aanwending van die hoogste OLTs, was altyd laer as 1 000 mg.L-1. Dit is merkbaar laer as die limiet vir besproeiing van tot en met 50 m3 per dag in Suid-Afrika. Maar, dit was nogtans regdeur hoër as die limiet van 75 mg.L-1 vir veilige storting in ‘n varswaterbron.
16

Βιοτεχνολογικές μέθοδοι επεξεργασίας υγρών αποβλήτων ελαιοτριβείου / Biotechnological methods for olive mill wastewater treatment

Μπλίκα, Παρασκευή 14 September 2010 (has links)
Τα υγρά απόβλητα ελαιοτριβείου (ΥΑΕ) παράγονται κατά την εξαγωγή του ελαιόλαδου από τα παραδοσιακά και τα φυγοκεντρικά ελαιοτριβεία τριών φάσεων. Τα ΥΑΕ έχουν διαφορετικά χαρακτηριστικά τα οποία εξαρτώνται από τη διαδικασία παραγωγής και τον τύπο των ελιών που χρησιμοποιούνται. Τα περισσότερα ελαιοτριβεία στην Ελλάδα χρησιμοποιούν την τριφασική διαδικασία εξαγωγής του ελαιόλαδου. Παρόλα αυτά, κάποια καινούρια χρησιμοποιούν τη διφασική διαδικασία εξαγωγής του ελαιολάδου. Παραδοσιακά ελαιοτριβεία συνεχίζουν να υπάρχουν, αλλά σε μικρότερη έκταση. Τα ΥΑΕ αποτελούν ένα σημαντικό πρόβλημα για την περιοχή της Μεσογείου, όπου παράγεται το 95 % της παγκόσμιας παραγωγής ελαιολάδου, εξαιτίας της υψηλής τους συγκέντρωσης σε χημικά απαιτούμενο οξυγόνο (ΧΑΟ) και της ικανότητάς τους να αντιστέκονται στη βιοαποδόμηση εξαιτίας της υψηλής τους περιεκτικότητας σε φαινολικές ενώσεις. Αυτές οι ενώσεις οφείλονται για το μαύρο χρώμα και τις φυτοτοξικές και αντιβακτηριδιακές ιδιότητες των ΥΑΕ. Διάφορες φυσικοχημικές μέθοδοι έχουν προταθεί για την επεξεργασία των ΥΑΕ, συμπεριλαμβανομένων της απλής συμπύκνωσης, της επίπλευσης και καθίζησης, της εξάτμισης και της χρήσης επιλεγμένων μεμβρανών, της ουδετεροποίησης με την προσθήκη H2SO4, της οξείδωσης με O3 και αντιδραστήριο Fenton, καθώς επίσης και την επαναχρησιμοποίηση των ΥΑΕ με διασκορπισμό σε αγροτικά εδάφη σαν λίπασμα. Σε ότι αφορά τις βιολογικές μεθόδους, οι αναερόβιες βιολογικές διεργασίες είναι ιδιαίτερα αποδοτικές εξαιτίας των γνωστών πλεονεκτημάτων που εμφανίζουν και σχετίζονται με την εξοικονόμηση ενέργειας και χημικών και της μικρής παραγωγής λάσπης, ειδικότερα όταν αφορά την επεξεργασία αποβλήτων με υψηλή συγκέντρωση ΧΑΟ. Η εποχιακή λειτουργία των ελαιοτριβείων (Νοέμβριος – Φεβρουάριος) δεν αποτελεί μειονέκτημα για τις αναερόβιες διεργασίες εξαιτίας των χαμηλών παρατηρούμενων ρυθμών αποδόμησης των μεθανογόνων μικροοργανισμών και της εύκολης επαναλειτουργίας των αναερόβιων χωνευτήρων μετά από αρκετούς μήνες μη λειτουργίας. Παρόλο που η αναερόβια χώνευση χρησιμοποιείται κατά κύριο λόγο για τη μείωση του υψηλού οργανικού φορτίου των ΥΑΕ, η παρουσία ενώσεων στα ΥΑΕ τοξικών προς τους μεθανογόνους φαίνεται να είναι ένα σημαντικό πρόβλημα για την αναερόβια επεξεργασία των ΥΑΕ. Μία προσέγγιση στο πρόβλημα θα ήταν η αραίωση του αποβλήτου ώστε να μειωθεί η συγκέντρωση των φαινολικών ενώσεων και των λιπαρών οξέων. Σε αυτή την περίπτωση εξετάζεται και η απομάκρυνση των στερών του αποβλήτου πριν την αναερόβια χώνευση. Μία δεύτερη προσέγγιση θα ήταν η εφαρμογή αερόβιας προεπεξεργασίας του αποβλήτου ώστε να απομακρυνθούν ενώσεις που είναι τοξικές για τα μεθανογόνα βακτήρια. Πιο συγκεκριμένα, ένα πρώτο στάδιο αερόβιας προεπεξεργασίας του ΥΑΕ με μύκητα λευκής σήψης, έχει προταθεί ως η πιο κατάλληλη μικροβιακή διεργασία προεπεξεργασίας για την επιλεκτική απομάκρυνση των φαινολικών. Στόχος της παρούσας διατριβής ήταν να μελετηθεί η ικανότητα του μύκητα λευκής σήψης Pleurotus ostreatus κάτω από άσηπτες ή μη συνθήκες να λειτουργήσει σε έναν καινοτόμο βιοαντιδραστήρα καθοδικής ροής και να διευρενηθεί η αποδοτικότητα εναλλακτικά της αραίωσης ή/και της προεπεξεργασίας στην αναερόβια χώνευση ΥΑΕ σε αναδευόμενο μεσόφιλο αντιδραστήρα. Επίσης, μελετήθηκε η αναερόβια χώνευση ΥΑΕ σε αντιδραστήρα τύπου ASBR και αντιδραστήρα PABR, αντίστοιχα. Μία καινοτόμος μέθοδος ακινητοποίησης των μυκήτων αποδείχτηκε κατάλληλη για την ανάπτυξη μιας αποδοτικής διεργασίας προεπεξεργασίας για την απομάκρυνση των φαινολικών. Η αναερόβια χώνευση είναι η πιο αποδοτική διεργασία για την επεξεργασία υγρών αποβλήτων ελαιοτριβείου. Παρόλα αυτά, αραίωση ή/και κάποιου τύπου προεπεξεργασία είναι απαραίτητη για την αποφυγή τοξικότητας των φαινολικών στους μεθανογόνους. Θερμική προεπεξεργασία ακολουθούμενη από καθίζηση ώστε να απομακρυνθεί το στερεό περιεχόμενο, από την άλλη, αποδείχτηκε ένας μη επιθυμητός τρόπος προεπεξεργασίας. Επιπλέον, αραιωμένο ΥΑΕ 1:1, χωρίς την απομάκρυνση των στερεών μπορεί να υποστεί επεξεργασία αποδοτικά σε υδραυλικό χρόνο παραμονής 30 ημέρες, εξασφαλίζοντας σταθερή παραγωγή βιοαερίου. Βιολογική προεπεξεργασία με μύκητα μπορεί να οδηγήσει σε σταθερή διεργασία σε υδραυλικό χρόνο παραμονής 30 ημέρες. Η αναερόβια επεξεργασία του αποβλήτου σε αντιδραστήρα ASBR είναι εφικτή με ισοδύναμο χρόνο παραμονής 30 ημερών χωρίς να αραιωθεί το απόβλητο. Η επεξεργασία σε αντιδραστήρα PABR είναι ωστόσο πιο αποδοτική εξαιτίας του σχεδόν κατά μία τάξη μεγέθους μικρότερο υδραυλικού χρόνου παραμονής (3.75 ημέρες), που αυτός μπορεί να λειτουργήσει και της μεγαλύτερης απόδοσης του σε βιοαέριο. Το αναερόβια επεξεργασμένο απόβλητο μπορεί να καταστεί κατάλληλο για διάθεση μετά από κατάλληλη επεξεργασία μεμβρανών (συνδυασμός υπερδιήθησης και αντίστροφης όσμωσης). / Olive mill wastewater (OMW) is produced during the extraction of oil from the olive fruit by the traditional mill and press process. ΟΜW has a wide range of characteristics depending on the type of the mill and the type of olive and equipment employed. Most of the mills in Greece use a 3-phase extraction process. However, some of the newer ones use the 2-phase extraction process. Traditional mills are still present but to a limited extent. OΜW treatment and disposal has become a critical environmental problem in the Mediterranean area that accounts for approximately 95% of the world olive oil production. This is because of its high organic chemical oxygen demand (COD) concentration, and because of its resistance to biodegradation due to its high content in phenolic compounds. These compounds are responsible for its dark color, and its phytotoxic and antibacterial properties. Various physico-chemical methods have been proposed for treating OMW, including simple evaporation, flotation and settling, vaporization and use of selected membranes, neutralization with addition of H2SO4, oxidation by O3 and Fenton reagent, as well as reuse of the OMW by spreading onto agricultural soil as an organic fertilizer. As far as biological processes are concerned, anaerobic biological processes are particularly suitable because of their well known advantages related to energy and chemicals saving and to the low production of sludge, especially when it comes to treatment of high COD wastewaters. The seasonal nature of the operation of olive mills (typically November to February) is not a disadvantage for anaerobic processes because the observed decay rates for methanogens are very low and a digester can be easily restarted following several months of shut-down. Although anaerobic digestion may be in principle used for reducing the high organic content of OMW, the presence of compounds toxic to methanogens in OMW appears to be a significant problem for the anaerobic digestion of OMW. One approach to the problem has been to sufficiently dilute the OMW to reduce the concentration of phenolics and fatty acids. In this case, the possibility of prior solids removal needs to be examined. A second approach has been the use of aerobic pretreatment of OMW to remove compounds that are toxic to methanogenic consortia. In particular, a preceding aerobic treatment of OMW with white-rot fungi, has been proposed as the most suitable microbial pretreatment process for the selective removal of phenolics. The aim of the present study was to study the ability of the white rot fungus Pleurotus ostreatus under aseptic or non aseptic conditions to function in a novel trickling filter immobilized fungi bioreactor and to investigate the feasibility of alternative dilution and/or pretreatment processes for the anaerobic digestion of olive-mill wastewater in a stirred tank mesophilic digester. The anaerobic digestion of OMW in an anaerobic sequencing batch reactor (ASBR) and in a periodic anaerobic baffled reactor (PABR) was also studied. A novel fungi immobilization method proved very suitable for the development of an efficient pretreatment process for phenolics removal. Anaerobic digestion is the most effective process for the treatment of olive mill wastewater. However, dilution and/or some type of pretreatment are necessary to avoid toxicity of the phenolics on the methanogens. Thermal pretreatment followed by sedimentation to remove the solids content, on the other hand proved to be an undesirable type of pretreatment. Diluted 1:1 raw OMW on the other hand, without any solids removal, can be effectively treated at an HRT of 30d, securing a stable high biogas yielding operation. Biological pre-treatment with fungi may lead to a stable process at an HRT of 30d. Anaerobic digestion of OMW using an ASBR (anaerobic sequencing batch reactor) is feasible at an equivalent HRT of 30d with the advantage that it can treat nondiluted wastewater. Treatment in a PABR, however, is much more effective as it requires an order-of –magnitude lower HRT ( 3.75 d) and yields large amounts of biogas. The anaerobically treated effluent is still not suitable for disposal. A membrane process such as reverse osmosis may be effectively used to render the anaerobically treated wastewater readily disposable.
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Digestion anaérobie d'effluents d'une conserverie de thon tunisienne : aspects biotechnologiques et microbiologiques. / Anaerobic digestion of Tunisian manure from a tuna cannery : biotechnology and microbiological aspects

Hamdi, Olfa 02 April 2015 (has links)
Deux réacteurs, R1 et R2, ont été alimentés quotidiennement avec les effluents à traiter à des TRH de 13 jours et de 20 jours, respectivement. Les résultats obtenus ont montré un taux d'abattement de la dégradation de la matière organique de 53% pour R2, contre 35% pour R1. Afin de mieux comprendre le fonctionnement biologique de ces réacteurs, nous avons exploré les communautés microbiennes d'importance écologique impliquées dans la dégradation de la matière organique contenue dans ces effluents. Cela a été réalisé dans un premier temps par des approches moléculaires en utilisant la technique de DGGE et le pyroséquençage 454. Nous avons alors montré que les représentants du domaine des Bacteria étaient les plus représentés dans les deux réacteurs par rapport aux Archaea avec une plus grande diversité au niveau du réacteur R2. Les séquences de Bacteria obtenues sont affiliées principalement aux phylums des Firmicutes, des Bacteroïdetes, et des Synergistetes, impliquées dans l'hydrolyse et la fermentation de la matière organique des effluents. Une mention particulière est à accorder aux membres du phylum des Synergistetes qui ont été également détectés par pyroséquençage 454. Dans les deux réacteurs, ce phylum majoritaire était représenté par deux familles, celle des "Dethiosulfovibrionaceae" et celle des "Aminiphilaceae" dont on sait qu'elles interviennant dans la dégradation des acides aminés. Enfin, l'approche culturale nous a permis d'isoler dans nos réacteurs plusieurs souches bactériennes anaérobies mésophiles hétérotrophes. Parmi celles-ci, nous avons pu décrire deux nouvelles espèces Desulfocurvus thunnarius et A thunnarium. / For this purpose, two ASBR reactors R1 and R2 were tested. They were fed daily with the industrial effluents at HRT of 13 days and 20 days, respectively. The results obtained during the anaerobic treatment showed a degradation rate of the organic matter of 53% for R2 against 35% for R1. In order to better understand this process, we explored the microbial communities of ecological importance involved in the degradation of organic matter in the effluent to be treated. This was accomplished by initiating molecular approaches. Using the DGGE technique and 454 pyrosequencing, we showed that representatives of the domain Bacteria were the most dominant in both reactors as compared to Archaea with a greater diversity observed in R2 reactor. Bacteria sequences were affiliated to the phyla Firmicutes, Bacteroidetes and Synergistetes, known to be involved in the hydrolysis and fermentation of organic matter. A particular mention is given to members of the phylum Synergistetes which were also detected by pyrosequencing 454. In both reactors, this phylum was represented by two families, the "Dethiosulfovibrionaceae" and that of "Aminiphilaceae" which are recognized as significant amino acids degraders. Finally, the cultivation approach allowed us to isolate several mesophilic heterotrophic anaerobic bacteria. Among them, a new sulfate-reducing species belonging to the family Desulfovibrionaceae, Desulfocurvus thunnarius, and A thunnarium.

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