Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17542号 / 工博第3701号 / 新制||工||1563(附属図書館) / 30308 / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 高岡 昌輝, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当

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.

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.

Este trabalho apresenta e discute os resultados obtidos na operação de quatro reatores anaeróbios operados em bateladas seqüenciais, projetados em escala piloto, para tratamento de 7,8 m3.dia-1 de esgotos sanitários, coletados da rede coletora que atravessa o Campus da USP de São Carlos. Cada sistema (1,2 m3) foi concebido para tratamento de 1,95 m3.dia-1 de esgoto sanitário, com concepções geométricas (relação L-altura/D-diâmetro), mecânicas (agitação mecânica ou recirculação de líquido) e tipo de retenção de biomassa diferentes. Três unidades eram do tipo ASBR (anaerobic sequencing batch reactor) e outro tipo ASBBR (anaerobic sequencing batch biofilm reactor) com leito fixo composto de matrizes cúbicas de espuma de poliuretano. Os ciclos operacionais tinham duração de oito horas perfazendo no total três ciclos por dia em cada sistema. O monitoramento dos reatores incluiu a determinação de DQO, pH, sólidos em suspensão totais (SST) e voláteis, ácidos voláteis totais, alcalinidade no afluente e efluente, bem como a concentração de metano no biogás. O ensaio experimental foi dividido em duas etapas distintas, sendo que na primeira (227 dias), os reatores não receberam inóculo e na segunda (66 dias) houve a inoculação prévia de lodo anaeróbio granular. Em ambas etapas, os dois reatores ASBR com mesmo tipo de agitação por recirculação de líquido, mas com diferente relação L/D não apresentaram desempenho satisfatório. Os valores médios de eficiência de remoção de DQO e de SST foram próximos de 40% e 60%, respectivamente. No efluente a concentração média foi de 300 mgDQO/L e de 100 mgSST/L. Nos reatores, ASBR com agitação mecânica e, ASBBR com biomassa imobilizada, os resultados médios obtidos foram melhores. O reator ASBBR atingiu eficiência média de 65% e 75% em remoção de DQO e SST, enquanto no ASBR com agitação mecânica chegou-se a 60% e 85%, respectivamente. A concentração média no efluente dos reator foi de 150 mgDQO/L e 60 mgSST/L no ASBBR e 220 mgDQO/L e 50 mgSST/L no ASBR com agitação mecânica. / This study reports and discuss several data obtained using four pilot scale anaerobic sequencing batch reactor, treating 7.8 m3.d-1 of domestic sewage from the Sao Paulo University sewer treatment system (Campus- São Carlos). Each reactor system (1.2 m3) was designed for the treatment of 1.95 m3.d-1 of domestic sewage with different geometric reactor characteristics (ratio L-length/D-diameter), mechanical (mechanical mixing or liquor re-circulation) and biomass retention type. Three reactors were a conventional ASBR (anaerobic sequencing batch reactor) with granular biomass and another one, an anaerobic sequencing batch biofilm reactor (ASBBR), which was composed with cubic matrices of polyurethane foam. The reactors were operated within 8-h of a sequential batch cycle, which were attained in three cycles by day for each system. Chemical oxygen demand (COD), pH, total suspended solids (TSS), volatile fatty acids, bicarbonate alkalinity in both the influent and effluent were monitored in the different cycles. Methane concentration was also assessed in the same period using Gas Chromatography (GC). The experiments were divided in two different phases. In the first phase, which corresponded to 227 d, the reactors were not inoculated. In the second phase (66 d) the reactors were then inoculated with anaerobic granular sludge. It was observed that in both operational phases, the two ASBR reactors, with the same re-circulating process of the mixed liquor, but with different L/D ratio, showed non-satisfactory results. The average values of COD and TSS removal were close to 40 and 60%, respectively. In the effluent, the average values were of 300 mgDQO/L and 100 mgTSS/L. ASBR reactors with mechanical mixing and ASBBR reactor with immobilized biomass showed better results. The average removal efficiency observed was of 65 and 75% for COD and TSS, respectively. ASBR reactors with mechanical mixing reached the efficiency of 60 and 85% for COD and TSS removal. The average concentration in the effluent was of 150 mgDQO/L and 60 mgSST/l in the ASBBR reactor; and 220 mgCOD/L and 50 mgTSS/L in the ASBR reactor with mechanical mixing.

Este trabalho apresenta e discute os resultados obtidos na operação de quatro reatores anaeróbios operados em bateladas seqüenciais, projetados em escala piloto, para tratamento de 7,8 m3.dia-1 de esgotos sanitários, coletados da rede coletora que atravessa o Campus da USP de São Carlos. Cada sistema (1,2 m3) foi concebido para tratamento de 1,95 m3.dia-1 de esgoto sanitário, com concepções geométricas (relação L-altura/D-diâmetro), mecânicas (agitação mecânica ou recirculação de líquido) e tipo de retenção de biomassa diferentes. Três unidades eram do tipo ASBR (anaerobic sequencing batch reactor) e outro tipo ASBBR (anaerobic sequencing batch biofilm reactor) com leito fixo composto de matrizes cúbicas de espuma de poliuretano. Os ciclos operacionais tinham duração de oito horas perfazendo no total três ciclos por dia em cada sistema. O monitoramento dos reatores incluiu a determinação de DQO, pH, sólidos em suspensão totais (SST) e voláteis, ácidos voláteis totais, alcalinidade no afluente e efluente, bem como a concentração de metano no biogás. O ensaio experimental foi dividido em duas etapas distintas, sendo que na primeira (227 dias), os reatores não receberam inóculo e na segunda (66 dias) houve a inoculação prévia de lodo anaeróbio granular. Em ambas etapas, os dois reatores ASBR com mesmo tipo de agitação por recirculação de líquido, mas com diferente relação L/D não apresentaram desempenho satisfatório. Os valores médios de eficiência de remoção de DQO e de SST foram próximos de 40% e 60%, respectivamente. No efluente a concentração média foi de 300 mgDQO/L e de 100 mgSST/L. Nos reatores, ASBR com agitação mecânica e, ASBBR com biomassa imobilizada, os resultados médios obtidos foram melhores. O reator ASBBR atingiu eficiência média de 65% e 75% em remoção de DQO e SST, enquanto no ASBR com agitação mecânica chegou-se a 60% e 85%, respectivamente. A concentração média no efluente dos reator foi de 150 mgDQO/L e 60 mgSST/L no ASBBR e 220 mgDQO/L e 50 mgSST/L no ASBR com agitação mecânica. / This study reports and discuss several data obtained using four pilot scale anaerobic sequencing batch reactor, treating 7.8 m3.d-1 of domestic sewage from the Sao Paulo University sewer treatment system (Campus- São Carlos). Each reactor system (1.2 m3) was designed for the treatment of 1.95 m3.d-1 of domestic sewage with different geometric reactor characteristics (ratio L-length/D-diameter), mechanical (mechanical mixing or liquor re-circulation) and biomass retention type. Three reactors were a conventional ASBR (anaerobic sequencing batch reactor) with granular biomass and another one, an anaerobic sequencing batch biofilm reactor (ASBBR), which was composed with cubic matrices of polyurethane foam. The reactors were operated within 8-h of a sequential batch cycle, which were attained in three cycles by day for each system. Chemical oxygen demand (COD), pH, total suspended solids (TSS), volatile fatty acids, bicarbonate alkalinity in both the influent and effluent were monitored in the different cycles. Methane concentration was also assessed in the same period using Gas Chromatography (GC). The experiments were divided in two different phases. In the first phase, which corresponded to 227 d, the reactors were not inoculated. In the second phase (66 d) the reactors were then inoculated with anaerobic granular sludge. It was observed that in both operational phases, the two ASBR reactors, with the same re-circulating process of the mixed liquor, but with different L/D ratio, showed non-satisfactory results. The average values of COD and TSS removal were close to 40 and 60%, respectively. In the effluent, the average values were of 300 mgDQO/L and 100 mgTSS/L. ASBR reactors with mechanical mixing and ASBBR reactor with immobilized biomass showed better results. The average removal efficiency observed was of 65 and 75% for COD and TSS, respectively. ASBR reactors with mechanical mixing reached the efficiency of 60 and 85% for COD and TSS removal. The average concentration in the effluent was of 150 mgDQO/L and 60 mgSST/l in the ASBBR reactor; and 220 mgCOD/L and 50 mgTSS/L in the ASBR reactor with mechanical mixing.

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.

Neste trabalho de doutorado utilizou-se um reator anaeróbio em batelada seqüencial contendo biomassa imobilizada em matrizes cúbicas de espuma de poliuretano e agitação mecânica, com volume total de 5.5 L e volume útil de 4.5 L. A agitação do meio líquido foi realizada com quatro tipos de impelidores (turbina tipo hélice, lâminas planas, lâminas planas inclinadas e lâminas curvas, testados individualmente, sempre em número de 3), com 6 cm de diâmetro. A pesquisa foi realizada em quatro etapas experimentais. A etapa 1 objetivou determinar o tempo de mistura no reator para cada tipo de impelidor, ou seja, o tempo necessário para que o meio líquido ficasse totalmente homogêneo. A etapa 2 objetivou selecionar o tipo de impelidor e a respectiva intensidade de agitação que garantisse a minimização da resistência à transferência de massa externa no sistema. As intensidades de agitação testadas variaram de 200 a 1100 rpm, dependendo do tipo de impelidor. A etapa 3 foi realizada com tipo de impelidor e intensidade de agitação definidos na etapa 2, mas variando-se o tamanho da biopartícula (0,5, 1,0, 2,0 e 3,0 cm de aresta). O objetivo desta etapa foi selecionar o tamanho de biopartícula que minimizasse a resistência à transferência de massa interna. De posse das condições operacionais otimizadas (tipo de impelidor, intensidade de agitação e tamanho de partícula de suporte), a etapa 4 constituiu na aplicação das mesmas para o tratamento de um resíduo real, sendo escolhida água residuária de suinocultura. Na etapa 1, os resultados mostraram que os tempos de mistura para todos os tipos de impelidores foram desprezíveis em relação ao tempo total de ciclo. A etapa 2 revelou tempos de partida muito curtos (cerca de 20 dias), em todas as condições testadas, sendo atingidas remoções de DQO próximas de 70%. Além disso, o tipo de impelidor exerceu grande influência na qualidade final do efluente, fato este claramente constatado quando as frações de DQO foram consideradas separadamente (filtrada e suspensa). De acordo com os resultados obtidos na etapa 3, o tamanho da biopartícula teve influência decisiva no desempenho do sistema, nas condições testadas. As velocidades de dissolução foram aparentemente influenciadas pelo empacotamento do leito de espuma, enquanto que o consumo da fração de DQO correspondente às amostras filtradas foi provavelmente influenciado por fatores mais complexos. Finalmente, o teste realizado com resíduo diluído de suinocultura demonstrou que a operação do reator em estudo para o tratamento deste tipo de água residuária é possível. Os dados operacionais mostraram que o reator permaneceu estável durante o período testado. A agitação mecânica provou ser eficiente para melhorar a degradação da DQO suspensa, um dos maiores problemas no tratamento deste tipo de água residuária. Sendo assim, de acordo com os dados experimentais obtidos ao longo do trabalho, pode-se afirmar que a agitação em reatores em batelada mostrou-se importante não somente para proporcionar boas condições de mistura ou melhorar a transferência de massa na fase líquida, mas também para melhorar a solubilização da matéria orgânica particulada, melhorando as velocidades de consumo de matéria orgânica. / The bench-scale anaerobic sequencing batch reactor containing immobilized biomass and provided with mechanical stirring employed in this work had total and useful volumes of 5.5 and 4.5 L, respectively. The biomass was immobilized on cubic polyurethane foam matrices, and the agitation of the liquid medium was provided by four types of impellers (propeller, flat-blade, pitched-blade and curved-blade turbines, individually tested, always in a set of three), with 6 cm of diameter. The research was divided into 4 experimental steps. The first one aimed at determining the mixing time in the reactor for each sort of impeller, i.e., the time necessary for the system to be completely homogeneized. As for the second step, its objective was to choose the sort of impeller and the agitation rate suitable for minimizing the external mass-transfer resistance. The agitation rates tests ranged from 200 to 1100 rpm, depending on the impeller type. The step 3 was carried out utilizing the chosen impeller and agitation rate, but varying the bioparticle size (0.5, 1.0, 2.0 and 3.0 cm of side). The aim of these experiments was to determine the bioparticle size that minimized the solid-phase mass transfer. Using these optimized operational conditions (type of impeller and bioparticle size), the step 4 consisted of the utilization of them in the treatment of a real wastewater (diluted swine manure). As for the results, step 1 showed the mixing times were very low compared to the total cycle times employed in the experiments (8 and 24 h). Very short start-up periods were revealed by the second experimental part (about 20 days in average) for all conditions tested, and the removal efficiencies reached approximately 70%. Besides that, the impeller type exerted great influence on the final quality of the effluent, fact clearly observed when the COD fractions were analyzed separately (filtered and suspended). According to the data obtained in the step 3, the bioparticle size influenced decisively on the performance of the system, in the conditions tested. The bed packing apparently influenced the dissolution rates, whereas the consumption of the COD correspondent to the filtered samples was defined by more complex factors. Finally, the test with the diluted swine manure demonstrated that the operation of this reactor with this type of wastewater is feasible, as the operational data showed the reactor remained stable during all the period tested. The mechanical stirring proved to be efficient to improve the degradation of the suspended COD, one of the major problems in the treatment of this type of wastewater. In this sense, according to the experimental data obtained in this work, it can be affirmed the mechanical stirring in anaerobic sequencing batch reactors showed to be not only important to provide good mixing conditions and improve the liquid phase mass transfer, but also to improve the solubilization of the particulate organic matter and increase the overall organic matter consumption rates.

Neste trabalho de doutorado utilizou-se um reator anaeróbio em batelada seqüencial contendo biomassa imobilizada em matrizes cúbicas de espuma de poliuretano e agitação mecânica, com volume total de 5.5 L e volume útil de 4.5 L. A agitação do meio líquido foi realizada com quatro tipos de impelidores (turbina tipo hélice, lâminas planas, lâminas planas inclinadas e lâminas curvas, testados individualmente, sempre em número de 3), com 6 cm de diâmetro. A pesquisa foi realizada em quatro etapas experimentais. A etapa 1 objetivou determinar o tempo de mistura no reator para cada tipo de impelidor, ou seja, o tempo necessário para que o meio líquido ficasse totalmente homogêneo. A etapa 2 objetivou selecionar o tipo de impelidor e a respectiva intensidade de agitação que garantisse a minimização da resistência à transferência de massa externa no sistema. As intensidades de agitação testadas variaram de 200 a 1100 rpm, dependendo do tipo de impelidor. A etapa 3 foi realizada com tipo de impelidor e intensidade de agitação definidos na etapa 2, mas variando-se o tamanho da biopartícula (0,5, 1,0, 2,0 e 3,0 cm de aresta). O objetivo desta etapa foi selecionar o tamanho de biopartícula que minimizasse a resistência à transferência de massa interna. De posse das condições operacionais otimizadas (tipo de impelidor, intensidade de agitação e tamanho de partícula de suporte), a etapa 4 constituiu na aplicação das mesmas para o tratamento de um resíduo real, sendo escolhida água residuária de suinocultura. Na etapa 1, os resultados mostraram que os tempos de mistura para todos os tipos de impelidores foram desprezíveis em relação ao tempo total de ciclo. A etapa 2 revelou tempos de partida muito curtos (cerca de 20 dias), em todas as condições testadas, sendo atingidas remoções de DQO próximas de 70%. Além disso, o tipo de impelidor exerceu grande influência na qualidade final do efluente, fato este claramente constatado quando as frações de DQO foram consideradas separadamente (filtrada e suspensa). De acordo com os resultados obtidos na etapa 3, o tamanho da biopartícula teve influência decisiva no desempenho do sistema, nas condições testadas. As velocidades de dissolução foram aparentemente influenciadas pelo empacotamento do leito de espuma, enquanto que o consumo da fração de DQO correspondente às amostras filtradas foi provavelmente influenciado por fatores mais complexos. Finalmente, o teste realizado com resíduo diluído de suinocultura demonstrou que a operação do reator em estudo para o tratamento deste tipo de água residuária é possível. Os dados operacionais mostraram que o reator permaneceu estável durante o período testado. A agitação mecânica provou ser eficiente para melhorar a degradação da DQO suspensa, um dos maiores problemas no tratamento deste tipo de água residuária. Sendo assim, de acordo com os dados experimentais obtidos ao longo do trabalho, pode-se afirmar que a agitação em reatores em batelada mostrou-se importante não somente para proporcionar boas condições de mistura ou melhorar a transferência de massa na fase líquida, mas também para melhorar a solubilização da matéria orgânica particulada, melhorando as velocidades de consumo de matéria orgânica. / The bench-scale anaerobic sequencing batch reactor containing immobilized biomass and provided with mechanical stirring employed in this work had total and useful volumes of 5.5 and 4.5 L, respectively. The biomass was immobilized on cubic polyurethane foam matrices, and the agitation of the liquid medium was provided by four types of impellers (propeller, flat-blade, pitched-blade and curved-blade turbines, individually tested, always in a set of three), with 6 cm of diameter. The research was divided into 4 experimental steps. The first one aimed at determining the mixing time in the reactor for each sort of impeller, i.e., the time necessary for the system to be completely homogeneized. As for the second step, its objective was to choose the sort of impeller and the agitation rate suitable for minimizing the external mass-transfer resistance. The agitation rates tests ranged from 200 to 1100 rpm, depending on the impeller type. The step 3 was carried out utilizing the chosen impeller and agitation rate, but varying the bioparticle size (0.5, 1.0, 2.0 and 3.0 cm of side). The aim of these experiments was to determine the bioparticle size that minimized the solid-phase mass transfer. Using these optimized operational conditions (type of impeller and bioparticle size), the step 4 consisted of the utilization of them in the treatment of a real wastewater (diluted swine manure). As for the results, step 1 showed the mixing times were very low compared to the total cycle times employed in the experiments (8 and 24 h). Very short start-up periods were revealed by the second experimental part (about 20 days in average) for all conditions tested, and the removal efficiencies reached approximately 70%. Besides that, the impeller type exerted great influence on the final quality of the effluent, fact clearly observed when the COD fractions were analyzed separately (filtered and suspended). According to the data obtained in the step 3, the bioparticle size influenced decisively on the performance of the system, in the conditions tested. The bed packing apparently influenced the dissolution rates, whereas the consumption of the COD correspondent to the filtered samples was defined by more complex factors. Finally, the test with the diluted swine manure demonstrated that the operation of this reactor with this type of wastewater is feasible, as the operational data showed the reactor remained stable during all the period tested. The mechanical stirring proved to be efficient to improve the degradation of the suspended COD, one of the major problems in the treatment of this type of wastewater. In this sense, according to the experimental data obtained in this work, it can be affirmed the mechanical stirring in anaerobic sequencing batch reactors showed to be not only important to provide good mixing conditions and improve the liquid phase mass transfer, but also to improve the solubilization of the particulate organic matter and increase the overall organic matter consumption rates.