Thesis (MSc Food Sc )--Stellenbosch University, 2002. / ENGLISH ABSTRACT: South Africa is a developing country that relies heavily on its agricultural sector for economical welfare especially in the Western Cape Province. However, development gives rise to new technologies, new products, economical stability and unfortunately also to the production of larger volumes of liquid and solid waste. Anaerobic composting is becoming a very attractive treatment option for solid waste disposal because of its unique operational advantages and two valueadded by-products, compost and biogas. Over the last decade progress has been made in anaerobic digestion of solid wastes, but no literature could be found on the anaerobic composting of apple and peach pomace. The main objective of this study was to develop a method to anaerobically compost apple and peach pomace. In the first phase important operational parameters were identified and a method was developed to optimise the parameters. In the second phase of the study, the scaling-up and optimisation of the process were the major objectives. During the first phase of this research 2 L modified glass containers were used as composting units. The most important operational parameters (leachate pH, inoculum source and size, and initial moisture levels) were identified. Anaerobic compost from previous tests, brewery granules and anaerobic sludge were also used as inocula and evaluated for the best source of microbes. After optimising all the identified parameters, good results were obtained, which included higher biogas production, good volume reductions, less bad aromas and a compost product with a neutral pH. After developing the 2 L laboratory-scale method to compost the apple pomace anaerobically, the next step was to ascertain if the method would work if larger volumes of solid fruit waste were composted. A special 20 L composting unit made of PVC was designed to suit the operational requirements of the anaerobic composting process. It was also decided to mix apple pomace and peach pulp together and to use this solid waste source as part of the composting substrate. Different inocula, including cattle manure, anaerobic sludge, brewery granules and anaerobic compost produced in the previous tests, were used. Although good results were obtained with the anaerobic compost and cattle manure as inoculum, the aim was also to decrease the composting period by shortening the pH stabilisation period. To achieve this, it was decided to add NaHC03 to the substrate to be composted to facilitate a faster pH stabilisation. The composting period was subsequently shortened to 25 days with satisfactory results, which included a volume reduction, biogas production and faster pH stabilisation. An upflow anaerobic sludge blanket (UASB) bioreactor was also used to assist the composting process by facilitating the removal of the VFA's present in the composting leachate. This proved to be a valuable addition to the composting process as the UASB bioreactor also provided the composting units with a 'moisturising liquid', which was 'enriched' with a consortium of active anaerobic bacteria when the effluent from the bioreactor was re-added to the composting units. With all the operational parameters in place, good results were obtained and these included a volume reduction of 60% (m/m), a good biogas production, a composting period of only 25 days, a compost that was free of bad aromas, a final compost pH of > 6.5, final leachate COD values of less than 3 000 rnq.l", and a final leachate VFA's concentration of between 0 and 250 rnq.l". If in future research further scaling-up is to be considered, it is recommended that the composting unit be coupled directly to the UASB bioreactor, thus making the process continuous and more practical to operate. If the operational period of the anaerobic composting set-up could be further shortened and the inoculum adapted so that the process could be used for the treatment of other difficult types of solid wastes, it would probably be advantageous for the fruit processing industry to use this method as an environmental control technology. / AFRIKAANSE OPSOMMING: Suid-Afrika is 'n ontwikkelende land wat baie afhanklik is van die sukses van die landbousektor vir ekonomiese welstand, veral in die Wes Kaap Provinsie. Ontwikkeling gaan gepaard met nuwe tegnologie, nuwe produkte, ekonomiese stabiliteit en daarmee saam gaan die produksie van groter volumes vlooiebare en soliede afvalprodukte. Anaërobiese kompostering is tans besig om opgang te maak as en doeltreffende behandelingstegnologie vir vaste afvalstowwe. Tydens die laaste dekade is baie vooruitgang gemaak in die veld van anaërobiese vertering asook kompostering van afvalmateriaal met en hoë vaste stof inhoud. Anaërobiese kompostering van appel- en perskepulp, afkomstig van die versappingsindustrie, het tot dusver min aandag geniet. Die hoofdoel van hierdie navorsing was om 'n anaërobiese komposterings metode te ontwikkel vir die beheer van vrugte afval om sodoende die basis neer te lê vir en nuwe tegnologie wat baie voordele (biogas en kompos) inhou. In die eerste fase is die belangrikste operationele parameters geïdentifiseer om sodoende beter beheer oor die anaërobiese proses uit te oefen. In die tweede fase is die anaërobiese proses wat gedurende die eerste fase ontwikkel is, opgeskaal om optimum resultate te verkry. Gedurende die eerste fase van hierdie verhandeling was 2 L gemodifiseerde glas houers gebruik as komposteringseenhede. Die belangrikste operasionele parameters (pH beheer, inokulasie grootte, vloeistofvlakke en hoeveelheid vog asook vlugtige vetsuur produksie en verwydering) vir die beheer van die anaërobiese komposteringsproses was geïdentifiseer en gebruik as uitgangspunt om 'n anaërobiese komposteringsmetode te ontwikkel. Anaërobiese slyk, brouery granules en anaërobiese kompos van vorige eksperimente was as inokula gebruik. Gedurende hierdie studies was goeie resultate verkry en het 'n hoë biogas produksie, goeie volume reduksies, vermindering van slegte aromas en kompos met 'n neutrale pH ingesluit. . Nadat hierdie goeie resultate met die 2 L laboratorium-skaal metode verkry was, was groter volumes vaste vrugte afval gebruik om te bepaal of dieselfde metode toegepas kan word op en groter skaal. Spesiale 20 L komposteringseenhede was ontwerp om aan die operasionele vereistes van 'n anaërobiese proses te voldoen. Dit was ook besluit om appel pulp met perske pulp te meng en te gebruik as deel van die komposteringssubstraat. Verskeie inokula was weereens gebruik en het die volgende ingesluit: vars beesmis, anaërobiese slyk, brouery granules en anaërobiese kompos van vorige eksperimente. Hoewel baie goeie resultate met vars beesmis en anaërobiese kompos as inokula verkry was, was 'n volgende doel gewees om die kompoterings tydperk te verkort deur die pH vinniger te stabiliseer. Daar was besluit om NaHC03 by die komposteringssubstraat te voeg en so 'n vinniger pH stabilisasie te fasiliteer. 'n UASB ('upflow anaerobic sludge blanket') bioreaktor was ook gebruik om die komposteringsproses aan te help deur die vlugtige vetsure wat in die kompostloog teenwoordig was, te verwyder. Die insluiting van die bioreaktor in die anaërobiese komposteringsproses het bygedra tot die sukses van die proses deurdat die uitvloeisel as 'n vogmiddel vir die komposteringseenhede gebruik was en 'n konsortium van aktiewe anaërobiese bakterieë bevat het. Nadat al die operationele parameters in plek was, was goeie resultate bereik en het die volgende ingesluit: 'n volume reduksie van 60% (m/m), goeie biogas produksie, 'n komposteringstyd van 25 dae, 'n kompos wat vry was van slegste aromas, 'n finale kompos pH van >6.5, finale loog CSB van <3 000 rnq.l' en 'n finale vetsuur konsentrasie van tussen 0 en 250 mq.l'. lndien verdere navorsing onderneem word, word dit aanbeveel dat die UASB bioreaktor direk aan die komposteringseenheid gekoppel word om sodoende die proses meer aaneenlopend en die proses prakties makliker uitvoerbaar te maak. Indien die operationele tydperk nog korter gemaak kan word en die inokulum aanpasbaar kan wees om moeilik verteerbare afvalprodukte te akkomodeer, sal hierdie tegnologie baie voordelig wees as 'n metode om omgewingsbesoedeling te beheer

Made available in DSpace on 2015-03-03T11:52:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-09-06Bitstream added on 2015-03-03T12:06:23Z : No. of bitstreams: 1 000807962.pdf: 904239 bytes, checksum: 57c69c216cd1bad8465976c2fad345c9 (MD5) / A aplicação de reatores UASB (Upflow Anaerobic Sludge Blanket) passou a ocupar uma posição de destaque, principalmente no Brasil, face às condições ambientais de temperatura favoráveis, baixo custo, simplicidade operacional e baixa produção de sólidos. Com o intuito de aprimorá-lo, este estudo aliou as características construtivas e operacionais destes reatores com as dos Reatores Anaeróbios Compartimentados (RAC), caracterizados por oferecerem a possibilidade de separação das fases que ocorrem na digestão anaeróbia e o aumento do tempo de contato entre a biomassa e o efluente. Assim, foi projetado e construído um reator vertical, contendo dois tubos concêntricos em seu interior, visando à separação das etapas acidogênica e metanogênica, a partir da cinética de crescimento dos microrganismos presentes. A pesquisa teve como objetivo principal estudar o comportamento e avaliar o desempenho do reator UASB compartimentado sob nova configuração, no período de partida e operação, tratando esgoto doméstico. O monitoramento do sistema foi dividido em duas etapas: partida e operação. Durante a partida, os valores de pH e alcalinidade mantiveram-se estáveis dentro de uma faixa adequada. Os resultados apresentados durante seu monitoramente indicaram ainda, que o inóculo utilizado promoveu condições adequadas para a partida do reator, com remoção média de DQO de 53,8%, chegando a atingir 82,8% ao final desta etapa. Na segunda etapa de monitoramento, ocorreram diversos problemas relacionados à operação do sistema, ocasionando sua paralisação durante alguns dias. Os valores de pH encontraram-se dentro da faixa adequada, contudo, a alcalinidade sofreu variações quando houve interrupção no sistema. A remoção de matéria orgânica apresentou-se estável, mesmo após tais interrupções, com eficiência média de remoção de 80% para a DQO e 78% para a DBO. Além disso, ambas chegaram a alcançar 90% na ... / Application of UASB (Upflow Anaerobic Sludge Blanket) reactor has come to occupy a prominent position, especially in Brazil, due to favorable climatic conditions, low cost, operational simplicity and low production solids. In order to improve it, this study combined constructional and operational features of these reactors with the Compartmented Anaerobic Reactor (CAR), characterized by offering the possibility of phase separation occurring in the anaerobic digestion and increase the contact time between the biomass and effluent. Thus a vertical reactor was designed and constructed containing two concentric tubes inside, in order to separate the acidogenic and methanogenic steps from the kinetics of growth of microrganisms present. The research aimed to study the behavior and evaluate the performance of the UASB compartmentalized reactor under new configuration during starting and operation, treating domestic wastewater. The monitoring system was divided into two stages: starting and operating. During the start-up, the values of pH and alkalinity remained stable within a proper range. The results presented during its monitoring also indicated that the inoculum used promoted conditions for starting the reactor, with average COD removal of 53,8%, reaching 82,8% at the end of this step. In the second stage of monitoring, there were several problems related to system operation, causing a stoppage for a few days. The pH values were within the appropriate range, however, the alkalinity variations experienced when there was an interruption in the system. The removal of organic matter remained stable even after such interruption, with average removal efficiency of 80% to 78% for COD and BOD. Moreover, both even reached 90% removal efficiency

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Os conjuntos I e II foram compostos por dois reatores UASB em série com volumes de 908 e 350 L e de 908 e 188 L, respectivamente. No conjunto II, foi realizado pós tratamento do efluente em um reator operado em batelada sequencial (RBS) com alimentação contínua, com volume de 3000 L. As cargas orgânicas volumétricas (COV) aplicadas no primeiro reator dos conjuntos I e II variaram de 8,36 a 9,95 g DQO total (L d)-1 e de 7,83 a 11,6 g DQO total (L d)-1, respectivamente. As eficiências médias de remoção de DQO total, nitrogênio Kjeldahl (NK), fósforo total (P-total) foram elevadas e variaram de 95 a 97% e de 97 a 99%, de 64 a 67% e de 53 a 69%, e de 80 a 87% e de 71 a 89%, nos conjuntos I e II, respectivamente. As eficiências também foram elevadas para os metais Cu, Fe, Mn e Zn nos conjuntos I e II e variaram de 80 a 91% e de 63 a 80%, de 59 a 80% e de 51 a 72%, de 89 a 97% e de 81 a 98%, de 87 a 98% e de 91 a 99%, respectivamente. A semeadura do milho, foi realizado na safrinha 2009 e na safra 2009/2010, ambos em sistema de plantio direto e convencional, para a confecção de silagem. Os valores do pH observados na silagem não diferiram entre os tratamentos nas duas épocas de semeadura e nos sitemas de plantio direto e convencional. A adubação do milho para confecção de silagem, com dejeto bruto de suíno, com dejetos tratados em sistema anaeróbio e com os dejetos do pós-tratamento, quando comparada com a adubação mineral, não apresentou resultados com diferenças significativas na silagem na maioria dos atributos avaliados. O reúso dos efluentes tratados e do dejeto bruto, não promoveu alterações na nutrição da planta, porém os efluentes... / This study evaluated the performance of two sets of upflow anaerobic sludge blanket (UASB) installed in series. The sets I and II were composed of two UASB reactors in series with volumes of 908 and 350 L and 908 L and 188, respectively. In set II was conducted after the treatment of the effluent in a sequencing batch reactor (SBR) with continuous flux, with a volume of 3000 L. The volumetric organic loads (VOC) applied to the first reactor of the sets I and II ranged from 8.36 to 9.95 g total COD (L d) -1 and 7.83 to 11.6 g total COD (L d) -1, respectively. The average removal efficiencies of total COD, Kjeldahl nitrogen (NK), total phosphorus (total P) were high and ranged from 95 to 97% and 97 to 99%, 64 to 67% and 53 to 69% and 80 to 87% and 71 to 89% in clusters I and II, respectively. The efficiencies were also high for Cu, Fe, Mn and Zn in clusters I and II, and ranged from 80 to 91% and 63 to 80%, 59 to 80% and 51 to 72% from 89 to 97 and 81% to 98%, 87 to 98% and 91 to 99%, respectively. We carried out the swing of maize in the 2009 off-season and 2009/2010 season, both in no-tillage and conventional sistems for making silage. The pH values observed in the silage did not differ significantly between treatments in both seasons of swing and in the sistems of tillage and no-tillage. The fertilization of corn for silage making, with raw pig manure with waste treated in anaerobic system and the waste from the post-treatment compared to mineral fertilization, results showed no significant difference in silage in most parameters. The reuse of treated effluent and raw manure, did not promote changes in the nutrition of corn but the application of treated effluent increased concentrations of N readily available for plants in soil. Even in much larger doses applied compared to the raw waste, the treated effluent, promoted soil contamination by total coliforms and thermotolerant lower

Orientador: Tsunao Matsumoto / Banca: Liliane Lazzari Alberti / Banca: Marc Arpad Boncz / Resumo: A aplicação de reatores UASB (Upflow Anaerobic Sludge Blanket) passou a ocupar uma posição de destaque, principalmente no Brasil, face às condições ambientais de temperatura favoráveis, baixo custo, simplicidade operacional e baixa produção de sólidos. Com o intuito de aprimorá-lo, este estudo aliou as características construtivas e operacionais destes reatores com as dos Reatores Anaeróbios Compartimentados (RAC), caracterizados por oferecerem a possibilidade de separação das fases que ocorrem na digestão anaeróbia e o aumento do tempo de contato entre a biomassa e o efluente. Assim, foi projetado e construído um reator vertical, contendo dois tubos concêntricos em seu interior, visando à separação das etapas acidogênica e metanogênica, a partir da cinética de crescimento dos microrganismos presentes. A pesquisa teve como objetivo principal estudar o comportamento e avaliar o desempenho do reator UASB compartimentado sob nova configuração, no período de partida e operação, tratando esgoto doméstico. O monitoramento do sistema foi dividido em duas etapas: partida e operação. Durante a partida, os valores de pH e alcalinidade mantiveram-se estáveis dentro de uma faixa adequada. Os resultados apresentados durante seu monitoramente indicaram ainda, que o inóculo utilizado promoveu condições adequadas para a partida do reator, com remoção média de DQO de 53,8%, chegando a atingir 82,8% ao final desta etapa. Na segunda etapa de monitoramento, ocorreram diversos problemas relacionados à operação do sistema, ocasionando sua paralisação durante alguns dias. Os valores de pH encontraram-se dentro da faixa adequada, contudo, a alcalinidade sofreu variações quando houve interrupção no sistema. A remoção de matéria orgânica apresentou-se estável, mesmo após tais interrupções, com eficiência média de remoção de 80% para a DQO e 78% para a DBO. Além disso, ambas chegaram a alcançar 90% na ... / Abstract: Application of UASB (Upflow Anaerobic Sludge Blanket) reactor has come to occupy a prominent position, especially in Brazil, due to favorable climatic conditions, low cost, operational simplicity and low production solids. In order to improve it, this study combined constructional and operational features of these reactors with the Compartmented Anaerobic Reactor (CAR), characterized by offering the possibility of phase separation occurring in the anaerobic digestion and increase the contact time between the biomass and effluent. Thus a vertical reactor was designed and constructed containing two concentric tubes inside, in order to separate the acidogenic and methanogenic steps from the kinetics of growth of microrganisms present. The research aimed to study the behavior and evaluate the performance of the UASB compartmentalized reactor under new configuration during starting and operation, treating domestic wastewater. The monitoring system was divided into two stages: starting and operating. During the start-up, the values of pH and alkalinity remained stable within a proper range. The results presented during its monitoring also indicated that the inoculum used promoted conditions for starting the reactor, with average COD removal of 53,8%, reaching 82,8% at the end of this step. In the second stage of monitoring, there were several problems related to system operation, causing a stoppage for a few days. The pH values were within the appropriate range, however, the alkalinity variations experienced when there was an interruption in the system. The removal of organic matter remained stable even after such interruption, with average removal efficiency of 80% to 78% for COD and BOD. Moreover, both even reached 90% removal efficiency / Mestre

A escassez das fontes de fósforo e o alto consumo de energia associado à produção de fertilizantes nitrogenados serão problemas que deverão ser enfrentados no futuro. A recuperação de nutrientes das águas residuárias na forma de estruvita tem sido considerada como uma alternativa para atenuar estes problemas. Na América Latina, a produção de estruvita a partir de esgoto ainda não é uma tecnologia bem conhecida e, portanto, a finalidade deste trabalho é contribuir com uma melhor compreensão dos fenômenos envolvidos. Para isso, a pesquisa foi dividida em três etapas: 1) produção de estruvita a partir de efluente de reator anaeróbio de fluxo ascendente com manto de lodo (RAFA); 2) produção de estruvita a partir de sobrenadante de digestor anaeróbio de lodo de um processo com remoção biológica de fósforo (DALRBF) e 3) influência do cálcio na estruvita produzida na etapa 2. Nas três etapas, ajustaram-se as concentrações de magnésio, a fim de obter razões fósforo:magnésio (P:Mg) pré-estabelecidas, e o pH entre 8,00 e 10,50. Os resultados da primeira etapa mostraram que não foi possível produzir estruvita no efluente do RAFA nas condições testadas. No entanto, foram observadas remoções de fósforo e de nitrogênio, devido à formação de fosfatos de cálcio e de magnésio amorfos. Os resultados da segunda etapa comprovaram a viabilidade de produção de estruvita de sobrenadante de DALRBF e mostraram que os consumos molares dos íons fosfato (PO43-), amônio (NH4+) e magnésio (Mg2+) ou as remoções destes (%) não devem ser os únicos parâmetros para avaliar a formação de estruvita, pois outros compostos cristalizam ou precipitam e reduzem a qualidade do mineral. Para um meio com condições semelhantes às testadas nesta etapa, uma razão P:Mg 1:2 e um pH igual a 9,50 asseguram a máxima recuperação de nutrientes como estruvita com concentração mínima de impurezas, facilitando seu posterior uso como fertilizante. Os resultados da terceira etapa mostraram que uma fase amorfa de fosfato de cálcio ou de magnésio se forma na superfície da estruvita. / The shortage of the phosphorus sources and high-energy consumption associated to the nitrogen fertilizers production will be problems in the future. The nutrient recovery from wastewater as struvite has been considered as an alternative to alleviate these problems. In Latin America, production of struvite from wastewater is not yet a wellknown technology and therefore the purpose of this work is to contribute to a better understanding of the phenomena involved. This research work was performed in three phases: 1) production of struvite from upflow anaerobic sludge blanket reactor effluent; 2) production of struvite from anaerobic digester supernatant of enhanced biological phosphorus removal process (ADS-EBPR) and 3) influence of calcium in the struvite produced in the phase 2. In three phases, the magnesium concentrations were adjusted to obtain the preset phosphorus:magnesium (P:Mg) ratios and the pH was adjusted between 8,00 and 10,50. The results of the first phase showed that it is not possible to produce struvite in the upflow anaerobic sludge blanket reactor effluent in the tested conditions. However, removal of nitrogen and phosphorus was observed because amorphous calcium and magnesium phosphates were produced. The results of the second phase showed that it is possible to produce struvite in the ADS-EBPR and the molar consumptions of phosphate (PO43-), ammonia (NH4+) and magnesium (Mg2+) or removals (%) should not be the only parameters to evaluate the struvite formation, because other compounds crystallize or precipitate and reduce the quality of the mineral. In the similar conditions tested in this phase, a P:Mg ratio 1:2 and pH 9,50 assure maximum nutrients recovery as struvite with minimum impurities concentration, facilitating its subsequent use as fertilizer. The results of the third phase showed that amorphous calcium or magnesium phosphates were produced on the struvite surface.

O presente trabalho propõe uma metodologia científica, com critérios bem definidos, para avaliar e quantificar o desempenho ambiental e a renovabilidade de processos de tratamento de esgoto, numa base única: a exergia. O desempenho ambiental é quantificado através do cálculo da eficiência exergética ambiental, definida como a razão da exergia do efeito útil do processo pela exergia total consumida dos recursos humanos e naturais, incluindo todas as entradas exergéticas. O cálculo da renovabilidade é feito por meio do índice exergético de renovabilidade definido como como a razão entre a exergia dos produtos pela soma das exergias não renováveis, a exergia destruída, a exergia de desativação e a exergia das emissões e residuos. A metodologia foi aplicada a três processos de tratamento de esgoto: dois biológicos (aeróbio e anaeróbio) e um físico-químico (TQA). O cálculo dos indicadores exergéticos foi realizado para cada um destes processos e foi observado que o processo com maiores valores de desempenho ambiental e renovabilidade, considerando o metano e o lodo do processo como efeito útil, foi o processo RAFA Lagoa Facultativa, com valores respectivamente de n<exerg,amb> (0,983) e lâmbda(7,060). A análise dos resultados mostrou que a metodologia proposta é uma ferramenta útil na avaliação e comparação do desempenho ambiental e da renovabilidade de processos de tratamento de esgoto. / This work proposes a scientific methodology, with well defined criteria, to assess and quantify the environmental performance and renewability of wastewater treatment processes on a single base: the exergy. The environmental performance was measured by calculating the environmental exergy efficiency defined as the exergy ratio of the useful effect of the process to the total exergy consumed by human and natural resources, including all the exergy inputs. The renewability calculation was done using the renewability exergy index defined as the exergy ratio of the products to the sum of the non-renewable exergy, destroyed exergy, deactivation exergy and the emissions and waste exergy. The methodology was applied to three wastewater treatment processes: biological (aerobic and anaerobic) and physicochemical (CEPT) processes. The exergy indicators were calculated for each of these processes and it was observed that the process with the higher environmental performance and renewability values, considering the methane and sludge of process as useful effect, was the Facultative Lagoon UASB process, with values, respectively, of n<env,exerg>(0.983) and lambda(7.060). The results analysis showed that the proposed methodology is a useful tool in the evaluation and comparison of environmental performance and renewability of wastewater treatment processes.

A escassez das fontes de fósforo e o alto consumo de energia associado à produção de fertilizantes nitrogenados serão problemas que deverão ser enfrentados no futuro. A recuperação de nutrientes das águas residuárias na forma de estruvita tem sido considerada como uma alternativa para atenuar estes problemas. Na América Latina, a produção de estruvita a partir de esgoto ainda não é uma tecnologia bem conhecida e, portanto, a finalidade deste trabalho é contribuir com uma melhor compreensão dos fenômenos envolvidos. Para isso, a pesquisa foi dividida em três etapas: 1) produção de estruvita a partir de efluente de reator anaeróbio de fluxo ascendente com manto de lodo (RAFA); 2) produção de estruvita a partir de sobrenadante de digestor anaeróbio de lodo de um processo com remoção biológica de fósforo (DALRBF) e 3) influência do cálcio na estruvita produzida na etapa 2. Nas três etapas, ajustaram-se as concentrações de magnésio, a fim de obter razões fósforo:magnésio (P:Mg) pré-estabelecidas, e o pH entre 8,00 e 10,50. Os resultados da primeira etapa mostraram que não foi possível produzir estruvita no efluente do RAFA nas condições testadas. No entanto, foram observadas remoções de fósforo e de nitrogênio, devido à formação de fosfatos de cálcio e de magnésio amorfos. Os resultados da segunda etapa comprovaram a viabilidade de produção de estruvita de sobrenadante de DALRBF e mostraram que os consumos molares dos íons fosfato (PO43-), amônio (NH4+) e magnésio (Mg2+) ou as remoções destes (%) não devem ser os únicos parâmetros para avaliar a formação de estruvita, pois outros compostos cristalizam ou precipitam e reduzem a qualidade do mineral. Para um meio com condições semelhantes às testadas nesta etapa, uma razão P:Mg 1:2 e um pH igual a 9,50 asseguram a máxima recuperação de nutrientes como estruvita com concentração mínima de impurezas, facilitando seu posterior uso como fertilizante. Os resultados da terceira etapa mostraram que uma fase amorfa de fosfato de cálcio ou de magnésio se forma na superfície da estruvita. / The shortage of the phosphorus sources and high-energy consumption associated to the nitrogen fertilizers production will be problems in the future. The nutrient recovery from wastewater as struvite has been considered as an alternative to alleviate these problems. In Latin America, production of struvite from wastewater is not yet a wellknown technology and therefore the purpose of this work is to contribute to a better understanding of the phenomena involved. This research work was performed in three phases: 1) production of struvite from upflow anaerobic sludge blanket reactor effluent; 2) production of struvite from anaerobic digester supernatant of enhanced biological phosphorus removal process (ADS-EBPR) and 3) influence of calcium in the struvite produced in the phase 2. In three phases, the magnesium concentrations were adjusted to obtain the preset phosphorus:magnesium (P:Mg) ratios and the pH was adjusted between 8,00 and 10,50. The results of the first phase showed that it is not possible to produce struvite in the upflow anaerobic sludge blanket reactor effluent in the tested conditions. However, removal of nitrogen and phosphorus was observed because amorphous calcium and magnesium phosphates were produced. The results of the second phase showed that it is possible to produce struvite in the ADS-EBPR and the molar consumptions of phosphate (PO43-), ammonia (NH4+) and magnesium (Mg2+) or removals (%) should not be the only parameters to evaluate the struvite formation, because other compounds crystallize or precipitate and reduce the quality of the mineral. In the similar conditions tested in this phase, a P:Mg ratio 1:2 and pH 9,50 assure maximum nutrients recovery as struvite with minimum impurities concentration, facilitating its subsequent use as fertilizer. The results of the third phase showed that amorphous calcium or magnesium phosphates were produced on the struvite surface.

O presente trabalho propõe uma metodologia científica, com critérios bem definidos, para avaliar e quantificar o desempenho ambiental e a renovabilidade de processos de tratamento de esgoto, numa base única: a exergia. O desempenho ambiental é quantificado através do cálculo da eficiência exergética ambiental, definida como a razão da exergia do efeito útil do processo pela exergia total consumida dos recursos humanos e naturais, incluindo todas as entradas exergéticas. O cálculo da renovabilidade é feito por meio do índice exergético de renovabilidade definido como como a razão entre a exergia dos produtos pela soma das exergias não renováveis, a exergia destruída, a exergia de desativação e a exergia das emissões e residuos. A metodologia foi aplicada a três processos de tratamento de esgoto: dois biológicos (aeróbio e anaeróbio) e um físico-químico (TQA). O cálculo dos indicadores exergéticos foi realizado para cada um destes processos e foi observado que o processo com maiores valores de desempenho ambiental e renovabilidade, considerando o metano e o lodo do processo como efeito útil, foi o processo RAFA Lagoa Facultativa, com valores respectivamente de n<exerg,amb> (0,983) e lâmbda(7,060). A análise dos resultados mostrou que a metodologia proposta é uma ferramenta útil na avaliação e comparação do desempenho ambiental e da renovabilidade de processos de tratamento de esgoto. / This work proposes a scientific methodology, with well defined criteria, to assess and quantify the environmental performance and renewability of wastewater treatment processes on a single base: the exergy. The environmental performance was measured by calculating the environmental exergy efficiency defined as the exergy ratio of the useful effect of the process to the total exergy consumed by human and natural resources, including all the exergy inputs. The renewability calculation was done using the renewability exergy index defined as the exergy ratio of the products to the sum of the non-renewable exergy, destroyed exergy, deactivation exergy and the emissions and waste exergy. The methodology was applied to three wastewater treatment processes: biological (aerobic and anaerobic) and physicochemical (CEPT) processes. The exergy indicators were calculated for each of these processes and it was observed that the process with the higher environmental performance and renewability values, considering the methane and sludge of process as useful effect, was the Facultative Lagoon UASB process, with values, respectively, of n<env,exerg>(0.983) and lambda(7.060). The results analysis showed that the proposed methodology is a useful tool in the evaluation and comparison of environmental performance and renewability of wastewater treatment processes.