Дисертації з теми "Sewage sludge Australia Drying"

Mestrado em Sistemas Energéticos Sustentáveis
A brief review of the paper pulp production process in order to understand the origin of the sewage sludge was performed. Then a general revision of the current treatment options for this type of waste was addressed. The thermal treatment by combustion was focused and a review of the state of the art of this process was performed. The high moisture content of sludge was identified as a major concern. Thus a revision of the state of the art regarding thermal drying of sewage sludge was performed. The drying behavior of sewage sludge from the pulp and paper industry was evaluated by experiment in a drying tunnel. Strong shrinkage, cracks and a weak crust phenomenon were identified. A drying kinetic model was developed by the use of Artificial Neural Networks achieving a high Pearson correlation coefficient in the validation tests. Additionally a theoretical assessment of the co-combustion process was performed having into account a 50 MWth combustion facility. The inclusion of different portions of sewage sludge in a fuel mixture and the influence of the sludge moisture content was studied. It was found that burning sewage sludge with more than 50 wt% moisture content is not possible. Furthermore the inclusion of sewage sludge in a biomass fuel mixture causes an increase in the fuel consumption, solids production and heat losses in the flue gas. Based on general thermodynamic considerations the thermal power of a sludge dryer was calculated. The use of waste heat to supply the energy needs of the drying process was addressed by the waste heat availability estimation as sensible heat and latent heat at the stack of the facility. A set of combustion experiments were done in a pilot scale bubbling fluidized bed combustor to assess the combustion efficiency by monitoring the CO2, CO, H2O and O2 levels in conjunction with the temperature profile along the reactor height. Two different types of fuel samples were prepared. One composed by 100 wt% sewage sludge (fuel sample 1) and other composed by 50 wt% sewage sludge and 50 wt% residual forest biomass (particle size <1mm) (fuel sample 2). Low CO levels were onserved especially for the fuel sample 2 which indicates a very efficient combustion process. The CO emission level established by the Portuguese law for this type of reactor was never exceeded under typical operating conditions. The temperature profile along the reactor confirms that the combustion of the fuel samples prepared occurs mainly in the freeboard zone. It was not observed agglomeration problems and the fluidization conditions were kept constant during all the experimental tests. After the combustion experiments a considerable ashes quantity were found and its particle size distribution was estimated.
Foi realizada uma revisão sucinta do processo de produção de pasta de papel, a fim de compreender a origem da lama biológica. Uma revisão geral das opções atuais de tratamento para este tipo de resíduo foi abordada. O tratamento térmico por combustão foi focalizado e uma avaliação do estado da arte deste processo foi realizada. Foi verificado que o elevado teor de humidade da lama representa uma grande preocupação. Por tanto, realizou-se uma revisão do estado da arte em relação à secagem térmica das lamas. O comportamento da lama secundaria da indústria de pasta e papel foi estudado experimentalmente em um túnel de secagem. Foram observados os fenómenos de encolhimento e rachaduras além do fenomeno de crosta, embora este último não seja muito pronunciado. Foi desenvolvido um modelo de cinética de secagem com recurso ao uso de Redes Neurais Artificiais, sendo observado um elevado coeficiente de correlação nas experiências de validação. Foi realizada uma análise teórica ao processo de co-combustão de lama com biomassa florestal numa instalação de combustão de 50MWth. Estudou-se a inclusão de diferentes fracções de lama numa mistura de combustível contendo biomassa florestal, assim como também a influência do teor de humidade da lama. Verificou-se que a combustão de lamas biológicas com mais do que 50 wt% em teor de humidade não é possível. Além disso, a inclusão destas lamas na mistura de combustível provoca um aumento do consumo de combustível na instalação, da produção de sólidos e das perdas de calor no efluente gasoso da instalação. Com base em considerações termodinâmicas foi determinada a potência térmica de um secador de lamas. A utilização do calor residual para suprir as necessidades energéticas do processo de secagem foi abordada a través da estimativa da disponibilidade de calor residual na forma de calor sensível e calor latente no efluente gasoso da instalação de combustão. Foi realizado um conjunto de experiências de combustão de lamas e sua mistura com biomassa florestal num reactor de leito fluidizado borbulhante á escala piloto para avaliar a eficiência de combustão através da concentração de CO2, CO, O2 e H2O, em conjunto com o perfil de temperaturas ao longo do reactor. Foram utilizados dois tipos diferentes de amostras de combustível, uma composta por 100 wt% de lama biológica (combustível 1), e outra composta por 50 wt% de lama biológica e 50 wt% de biomassa florestal residual (tamanho de partícula <1mm) (combustível 2). Foram observados baixos níveis de CO no efluente gasoso, emparticular para a amostra de combustível 2, o qual indica um processo de combustão muito eficiente. Para condições de operação (temperatura e estequimetria) típicas, verificou-se que o limite de emissão de CO estabelecido pela lei Portuguesa para este tipo de fornalhas não foi excedido. O perfil de temperatura ao longo do reactor confirma que a combustão das amostras de combustível preparadas ocorre principalmente na zona do freeboard. Não foram verificados problemas de aglomeração e as condições de fluidização foram mantidas constantes durante todos os ensaios experimentais. Após os ensaios de combustão foi observada uma quantidade considerável de cinzas na fornalha, tendo sido avaliada a sua distribuição granulométrica.

Two different types of sludges from two popular sewage treatment systems were used in this study; namely, anaerobic pond sludge from a wastewater stabilisation pond system and filter pressed primary sludge from a primary sewage treatment plant. Under Egyptian conditions, Ascaris eggs represent the main health concern for sludge application on land and, accordingly, the effect of sand drying beds and a passive composting system (using agricultural wastes as bulking agents and cement dust as an additive to the sludge) were studied in terms of the inactivation of Ascaris eggs. From the characterisation and assessment of the anaerobic pond sludge from the Mit Mazah wastewater stabilisation pond system, it has been concluded that the sludge was well digested and free of viable Ascaris eggs. Consequently, this sludge is considered to be safe for land application, after appropriate dewatering. For the purposes of the study, anaerobic pond sludge was seeded with Ascaris vitilorum eggs (cattle ascarid). Within 30 days of dewatering on sand drying beds during the winter season (October and November), the Ascaris eggs were found to be inactivated only in the top layers, where the average solids content was approximately 85%. By the end of the two month drying period, the middle and bottom layers of sludge on the drying beds contained an average solids content of 74% to 77% and 72 to 73%, respectively, yet viable Ascaris eggs were still detected. During a second sludge application during the winter season (December and January), unfavourable weather conditions prevailed and, by the end of the 60 days drying period, total solids content averaged 54% in the top layer of sludge. The middle and bottom layers had an average total solids content of 49% and 44%, respectively. Throughout the winter drying period, all samples collected were positive for viable Ascaris eggs throughout the full depth of sludge. However, during the summer season, samples collected from the drying beds after 17 days of drying did not contain viable Ascaris eggs in the top sludge layers, where the solids content ranged from 74% to 63%. After one month of summer drying, no viable Ascaris eggs were detected throughout the entire depth of sludge on the drying beds and the lowest solids content recorded was 80% for the bottom layers. From this study, it can be concluded that, during the wet season in Egypt, drying beds were not efficient in destroying Ascaris eggs throughout the entire sludge depth. During the summer season, Ascaris eggs can be inactivated much more rapidly, compared to the winter season. Desiccation does not seem to be the only factor influencing the destruction of Ascaris eggs, with sludge temperature, solar radiation intensity and exposure time being possible major factors. By comparing the composting of filter pressed primary sludge in passive and windrow piles (used as control piles), it has been proved that the passive composting system is much more efficient in maintaining regular high temperatures in the composting mixture for a much longer duration (additional 10 days), due to the favourable aerobic conditions. Moreover, passive composting preserves the nitrogen content through the naturally controlled internal temperature, less need for turning and lower loss of moisture. By the end of the composting process, the total nitrogen content for the passive and windrow piles was a gain of 17.5% and a loss of 0.7%, respectively, while the ammoniacal nitrogen content in the product was 1109 mg/l and 837 m/l, respectively. From the hygienic point of view, passive composting technology proved to be much more effective in inactivating Ascaris eggs present in the primary sludge, compared to the windrow pile system. Viable Ascaris eggs were not detected after 30 days of composting using the passive system, compared with 60 days of composting for the windrow pile. Industrial cement dust as an additive and agricultural wastes (from fennel and basil production) were incorporated with sludge to form a range of composing mixtures. From the sludge/cement dust composting piles with agricultural wastes as bulking agent, it can be concluded that more than 35% concentration of cement dust was unfavourable for the decomposition process, due to the high pH and high temperature levels attained as a result of the effect of cement dust and dehydration of the organic matter. Moreover, loss of nitrogen was very high, due to the release of ammonia, encouraged by the high pH and high temperature in the composting mixture. The passive composting system was very efficient in naturally controlling the internal temperature in all the sludge/cement dust piles with bulking agent. Excessive heat was released to the atmosphere through the chimney effect created by the circulation of air through the perforated pipes and upwards into the pile. Internal temperatures for even the piles with the highest proportion of cement dust did not exceed 73°C. Inactivation of Ascaris eggs was achieved after only 15 days of composting for all the different cement dust concentrations, mainly due to the influence of high pH and high temperature levels for long periods but may also be due to the high release of ammonia gas. The passive composting of sludge amended with 30% cement dust without bulking agent was inefficient for both the decomposition process and inactivation of Ascaris eggs. No biological activity was taking place during the two months fermentation stage, due to the prevailing anaerobic conditions (lack of air voids and high moisture content) By considering all the different parameters for evaluating a treated compost, including the stability, maturity, nutrient content, heavy metals content and viable Ascaris eggs content for the sludge/cement dust piles with bulking agent, it can be concluded that more than 30% cement dust concentration would be unfavourable, according to the relatively high loss of nitrogen. More than 35% cement dust concentration is certainly unfavourable, mainly as a result of the delay of the decomposition process, the elongation of the composting period and the high loss of nitrogen content. There is no need to separate out the agricultural waste bulking materials after composting because they are organic in nature. Likewise, there is no need to consider separating out the cement dust, as the physicochemical analysis of the final sludge/cement compost with bulking materials showed its suitability for adding to agricultural land as an amendment. In conclusion, sand bed drying is considered to be a suitable process for dewatering of anaerobic stabilisation pond sludge in Egypt and, for extended periods between pond desludging of the order of 6 years, the dewatered sludge will be suitable for direct application to agricultural land. Passive composting is an appropriate technique for preparation of Egyptian filter pressed primary sludge for safe application to agricultural land. Cement dust additions of less than 30% concentration, to the composting mixture in a passive composting system produces sanitised and mature compost. The potential for co-disposal of agricultural wastes and cement kiln dust as bulking agents and additive, respectively, with sewage sludge in the production of compost, is very promising to produce a safe and beneficial outcome to the community.

Floc density measurements may play a significant role in analyzing sludge dewatering characteristics. A laboratory technique was developed to measure this property by means of isopycnic centrifugation. Four laboratory sludges were subjected to a series of dewatering tests: gravity thickening, centrifugation, vacuum filtration, and highâ pressure dewatering. Each sludge was analyzed for changing macro-and microâ properties during increasing stages of dewatering. It was concluded that sludge thickening rates are influenced by aggregate volume fractions, sludge density, suspension porosity, and the total surface area occupied by sludge aggregates. The extent of mechanical dewatering is impacted by similar parameters; namely, floc volume fractions, sludge density, cake porosity, and the total surface area occupied by sludge floc.

By interpreting the laboratory data, a model was formulated to describe changes in water distribution during the dewatering of sludges. This model includes a speculative view of the qualification and quantification of water-types.

Master of Science

Experiments were performed on alum, anaerobically digested and aerobically digested sludges to determine the optimum polymer conditioning for a belt filter press The optimum polymer dosages for all three zones of a belt filter press were compared with each other to determine the best overall conditioning. The requirements of all three zones of a belt filter press were the same. However, the gravity rate of drainage seems to under predict the dosages for optimum belt filter press performance. In addition the total mixing energy, G (the shear) and t (the mixing time), that represents the laboratory belt filter press was found to be approximately 45,000. Using a mixing energy input of 45,000 and a standard Buchner funnel apparatus the correct polymer dose for the belt filter press can be predicted.
Master of Science

Separation of liquid from solids is a necessary step in the ultimate disposal of wastewater sludges. Most commonly, sludges are dewatered by pressure-filtration methods. Mathematical models of the physics of the sludge dewatering process would provide the ability to predict dewatering performance and optimize the design and operation of dewatering facilities.

Conditioning studies were conducted on several water and wastewater sludges using polymers to determine the effect of high-intensity mixing on floc formation and breakup. Mechanisms acting in particle coagulation were also investigated. A rapid mixing apparatus was used in conditioning the sludge to simulate the high velocity gradients encountered in most dewatering equipment. Anionic and cationic polymers of varying molecular weights and an inorganic coagulant were chosen as the conditioning agents. Dewatering rates were measured by the capillary suction time (CST) apparatus. The effect of rapid mixing on the polymer efficiency was evaluated by premixing the polymer, using the same mixing apparatus, prior to applying it to condition the sludge. Data analyses revealed the great impact the primary floc breakup has on the sludge dewatering rate, although this was shown to be dependent on the nature of the sludge particles. Some minor changes were imparted to the polymer chains by intense mixing but there was no evidence that particle polymer bonds were fractured. The mechanisms of coagulation were observed to be related to sludge type. Overall, successful conditioning of sludges by polymers requires a proper determination of the sludge characteristics, a correct choice of polymer type and dose, and a knowledge of the mixing intensities.
Master of Science

The effects of coagulation pH and influent turbidity on aluminum and ferric hydroxide sludge macro-and micro-properties were investigated. To reduce the number of variables, sludges were produced under specific operating conditions in a 400 L/day continuous-flow pilot-plant. The effluent turbidity was monitored to evaluate process modifications. Sludge thickening and dewatering characteristics improved with reductions in the coagulation pH, increases in the influent turbidity levels, and/or reductions in the coagulant dose/influent turbidity ratio. Sludge floc/ aggregate density was the dominant sludge micro-property; sludges with superior thickening and dewatering characteristics were composed of higher density flocs/aggregates. A trade-off appeared to exist between improved sludge characteristics and effluent quality; however, verification will require additional research.
M.S.

Experiments were performed on samples of alum and activated sludges to determine if these sludges, conditioned with polymers under high-stress, would achieve favorable dewatering rates. Tests were conducted using a variable high speed mixer with root mean square velocity gradient (G) values ranging from 560 - 2000 sec⁻¹ with both anionic and cationic high molecular weight polymers. Capillary suction time (CST) was used to measure relative changes in dewatering rates. Results indicated that readily dewatered sludges can be obtained when subjected to high-stress mixing conditions. The most significant parameters governing high-stress conditioning were determined to be polymer dose and total mixing energy input (Gt). It was discovered that as Gt increases, polymer dose requirements increase as well, so as to maintain an optimum dewatering rate. Also, the activated sludges tested in the study appear to be resistant to the effects of polymer overdosing.
M.S.

Orientador: Meuris Gurgel Carlos da Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O lodo de esgoto, um dos principais componentes das águas residuárias geradas mundialmente, é um resíduo com alto conteúdo de umidade e grande carga de microrganismos. O uso da secagem apresenta-se como uma poderosa ferramenta na área ambiental devido a possibilidade de redução de volume e inativação microbiológica. O presente trabalho teve como objetivo avaliar o processo de secagem empregando um secador convectivo direto de fluxo ascendente, para redução de volume e inativação microbiológica de lodo de ETE. O lodo utilizado foi oriundo do tratamento primário da ETE - Tatu, da cidade de Limeira - SP. Foram desenvolvidos os seguintes estudos: determinação das características físico-químicas, ensaios de secagem a partir do planejamento experimental 3² em duplicata (duas variáveis - temperatura e vazão do ar de secagem, e três níveis) com análise estatística dos dados, a avaliação da redução de volume do lodo seco, ajuste de modelos matemáticos aos dados experimentais, verificação do efeito da sazonalidade do lodo de esgoto no processo de secagem, e avaliação da inativação microbiológica. Pelos resultados do trabalho verificou-se que as características físicoquímicas não sofreram alterações significativas antes e após o processo de secagem, e com isso, pode-se considerar que não ocorreu emissão atmosférica destes componentes. A cinética do processo de secagem se caracterizou inicialmente pelo período de aquecimento do material seguindo-se pelos períodos de secagem à taxa constante, 1.ª e 2.ª taxas decrescentes. O início do 2.º período de taxa decrescente foi marcado pela quebra ou fissura da torta, com aumento significativo da taxa de secagem, que é uma característica específica da secagem de materiais como o lodo. A análise estatística mostrou que a temperatura foi a variável mais significativa, indicando que o mecanismo de secagem do lodo de esgoto foi predominantemente difusivo. Contudo, devido o comportamento do 2.º período de secagem, os modelos difusivos não se ajustaram adequadamente, necessitando de modelos empíricos para descrever a 2.ª taxa decrescente. A redução de volume do material foi satisfatória, no caso cerca de 50%. A verificação da sazonalidade mostrou uma discreta diferença nos valores de pH e umidade inicial dos lodos estudados. As análises microbiológicas mostraram que após o tratamento térmico, houve a inativação microbiológica em praticamente todas as condições de processo estudadas, sendo o binômio tempo de exposição - temperatura o fator predominante para a esterilização e desinfecção do lodo de ETE. Com os resultados obtidos é possível considerar que o processo de secagem deste trabalho apresenta bom potencial de aplicação como tratamento de lodo de ETE, mas também de outros materiais que possuam características similares. Palavras-chave: secagem, lodo de esgoto, redução de volume, inativação microbiológica.
Abstract: Sludge, one of the main components of wastewater generated worldwide, is a waste with great quantity of moisture and microorganisms. The usage of drying has been a powerful tool in the environmental area due to the possibility of reduction of volume and microbiological inactivation. The present study aims to assess the drying process using an upflow direct convection dryer to reduce sludge volume and microbiological inactivation of Sludge Treatment Plants (STP). The used sludge has been taken from the primary treatment of STP - Tatu, city of Limeira, São Paulo. The following studies have been carried out: determination of physicochemical characteristics, drying experiments from the experimental design 3² in duplicate (two variables - temperature and drying air flow, and three levels) with statistical analysis of data, assessment of volume reduction of dried sludge, fitting of mathematical models to experimental data, verification of the effect of the seasonality of the sludge in the drying process, and assessment of microbiological inactivation. With the results of this study it could be verified that the physicochemical characteristics have not suffered significant changes nor before neither after the drying process, therefore, it can be said that atmospheric emission of these components have not occurred. The kinetics of the drying process was initially characterized by the heating period of the material followed by the drying periods of constant rate, first and second falling rates. The beginning of the second period of falling rate was marked by the cake break or fissure with the significant increase of the drying rate which is a specific characteristic of the drying of materials such as sludge. The statistic analysis has shown that the temperature was the most significant variable indicating that the sludge drying mechanism has predominantly been diffusive. However, due to the behavior of the second period of drying, the diffusive models did not adjust adequately, being necessary the use of empiric models to describe the second falling rate. The reduction of material volume was satisfactory, 50%, in this case. The verification of the seasonality has shown a discrete difference in the pH values and in the moisture content of the studied sludge. The microbiological analyses showed that after the thermal treatment there was microbiological inactivation practically in all the studied conditions of the process, being the binomial time of exposition - temperature the predominant factor for the sterilization and disinfection of sludge of STP. With the obtained results it is possible to consider that the drying process of this study shows a good potential of application for sludge treatment of STP, and also for other materials that have similar characteristics.
Doutorado
Engenharia de Processos
Doutor em Engenharia Química

This Diploma’s thesis is addressing the issues of technical drying, principles and types of technical drying, solar drying possible usefulness of sewage sludge in the Czech Republic, its availability during the season, the legislation related to the processing of sewage sludge and design of pilot scale solar dryer.

The master’s thesis is focused on the issue of solar drying of sewage sludge. The sludge management of wastewater treatment plants is described in the first part of this thesis. This theoretical part also deals with description of drying and dryers used for sludge treatment. The second part of the thesis is focused on the experimental solar drying of sewage sludge and the evaluation of the results.

Solární sušení je mimo jiné energeticky nenáročná a tudíž vysoce ekologická cesta pro zpracování kalů z malých čistíren odpadních vod. Výsledkem tohoto procesu je produkt, který je velmi dobře použitelný v zemědělství jako přírodní hnojivo. V rámci této práce bude sestaven zjednodušený dynamický model sušení vrstvy kalu s jednou prostorovou souřadnicí. Tento model bude diskretizován pomocí vhodné numerické metody a bude provedena jeho implementace do výpočtového programu v prostředí MATLAB.

Environmental pollution related to odour emission has become in the last years an important public concern. Closeness of odour-causing facilities such as waste water treatment plants (WWTPs) to urban areas further aggravates the problem. Volatile sulphur compounds (VSC) are one of the main groups of odour causing compounds in WWTPs, especially in the sludge processing. Nowadays, there are a variety of options available for the effective treatment of odorous sulphur compounds emission. This thesis has focused on the minimisation during sewage sludge conditioning process and the abatement of these compounds by treatments such as advanced oxidation processes and adsorption at the end-of-pipe
La contaminació atmosfèrica relacionada amb la emissió de males olors s’ha convertit en els darrers anys en un motiu de preocupació social. La proximitat d’instal·lacions causants de males olors com les estacions depuradores d’aigües residuals (EDAR) a les àrees urbanes, agreuja encara més el problema. Els compostos volàtils de sofre (CVS) són un dels principals grups de compostos causants de males olors, especialment en el tractament i processament dels fangs generats a les EDARs. Actualment, existeix una gran varietat d’opcions disponibles per al tractament efectiu de les emissions dels CVS causants de males olors. La present tesi s’ha focalitzat en la minimització de emissions durant el condicionament químic dels fangs i la eliminació mitjançant tractaments a final de procés com processos d'oxidació avançada o adsorció en carbons actius

European Union and states of European Union legislation are updated according new information about the composition and content of danger compounds in the sewage sludge from municipal waste water treatment plants. It has the effect on using of modern technologies for disposal in sewage sludge treatment. These methods are designed for sewage sludge hygienization, amount reduction, material transformation for next using or sludge incineration for energy production and utilization. The thesis is focuses on the effective thermal treatment of sewage sludge from waste water treatment plants. An important part of the line for sewage sludge incineration is pre-treatment and reduction of water content. The water content reducing is a high energy consumption process which is helpfull to use waste heat from energy plants where it would be loosed without using.

Studies in Europe, Japan, and North America have reported that wild fish exposed to treated sewage effluents can exhibit significant physiological and reproductive abnormalities consistent with exposure to hormonally active chemicals. The main objective of this research project was to examine the estrogenic and androgenic activity in treated sewage to determine the risk associated with treated sewage discharges in Australia and New Zealand. Several bioassays, including a sheep estrogen receptor and a rainbow trout androgen receptor binding assay, were set up and validated with model compounds. The assays were then used to measure the estrogenic and androgenic activity in sewage samples from 15 municipal sewage treatment plants (STP) utilizing a variety of treatment technologies. Raw sewage samples contained high levels of both estrogenic and androgenic activity, up to 185 ng/L estradiol equivalents (EEq) and up to 9330 ng/L testosterone equivalents (TEq), respectively. Secondary treatment processes such as activated sludge had the greatest impact on removal of biological activity from the wastewater. The estrogenic and androgenic activity in final treated effluents were <1 to 4.2 ng/L EEq and <6.5 to 736 ng/L TEq, respectively. Based on lowest observable effective concentrations reported in the literature, these levels are unlikely to induce biological effects in exposed fish in the short term. To examine potential long-term effects, resident mosquitofish chronically exposed to undiluted treated sewage were sampled. Several morphological biomarkers indicative of endocrine disruption were measured and compared with mosquitofish captured at a reference site. Mosquitofish captured in a constructed wetland for tertiary treatment of secondary treated sewage exhibited morphological differences such as elongated anal fins consistent with exposure to androgenic chemicals, although this effect was not measurable in fish collected at sites further downstream or at any of the other sites. Based on these results, it is unlikely that mosquitofish populations would be significantly affected by exposure to final treated sewage. A reverse transcription real-time polymerase chain reaction (RT-PCR) method to measure the production of a female-specific protein (vitellogenin) mRNA in adult male mosquitofish was developed, and this could be used as a rapid test to detect early changes in individuals exposed to estrogenic activity.

The first part of this diploma thesis targets in the formation of summary of methods of sewage sludge thermal treatment. Sludge is dangerous material rising from water treatment. Original water pollution is concentrated in sludge. Spectrum of the different methods of sludge disposal is very vast, thermal methods belong to the most advanced ones. Nowadays, legislative rules and regulations make more restrictive, hence sludge disposal is problematic because of economic and ecological view of point. The second part of this diploma thesis is dealt with perspective sludge management at the Central Waste Water Treatment Plant Prague concerning sludge drying and consequent sludge incineration.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Esta pesquisa sobre leito de secagem modificado com piso de blocos drenantes (wedge wire) foi desenvolvida em três etapas, sendo um acompanhamento em escala real com descartes de lodo aeróbio, outra realizada em escala piloto com descartes de lodo anaeróbio, ambos gerados em estação tratamento de esgoto sanitário (ETE), e a terceira etapa foi um levantamento de dados operacionais de alguns leitos com piso de blocos drenantes existentes no Brasil. O leito de secagem convencional de areia ainda é o método mais utilizado no Brasil para desaguamento de lodo em ETE de pequeno e médio porte. No entanto, devido ao aumento de fiscalização por órgãos ambientais, aumento de exigência por qualidade no tratamento de água e esgoto, custos elevados no gerenciamento, além de problemas com a eficiência de secagem final do lodo, odores e manutenção dos leitos, as empresas têm buscado alternativas de novas tecnologias, e/ou até mesmo por otimizações nos próprios leitos. Uma alternativa que tem se mostrado eficiente no desaguamento de lodos é o leito modificado com piso de blocos drenantes. Porém, ainda há pouca experiência com relação ao dimensionamento do leito, à sua operação e à sua eficiência por ser uma tecnologia pouca explorada no exterior e recém-chegada ao Brasil. Portanto esta pesquisa teve como objetivo avaliar o desaguamento de lodo de esgoto em leito com piso de blocos drenantes nas fases de drenagem e secagem. A drenagem do lodo foi avaliada através da vazão de drenagem após filtração de lodo no bloco drenante, da redução de volume de lodo no leito e da caracterização da qualidade da água drenada. Já a secagem foi avaliada a partir da variação do teor de sólidos totais do lodo durante o período de secagem. Como é um processo natural de secagem, o acompanhamento das condições climáticas local foi realizada. Os resultados foram satisfatórios tanto para o lodo aeróbio quanto para o anaeróbio. Em relação a drenagem, após um dia do descarte de lodo no leito com piso de blocos drenantes houve redução em torno de 90% do volume para lodo aeróbio e 70% para lodo anaeróbio. Já o teor de sólidos totais final obtido na secagem variou de acordo com o tipo de lodo, volume, taxa de aplicação de sólidos e condições climáticas. O melhor resultado de secagem para o lodo aeróbio foi de 95,3% de sólidos totais em 36 dias de secagem, e para o lodo anaeróbio, o máximo atingido foi de 63,5% em 24 dias, em condições de secagem diferentes.
This research about wedge wire floor sludge bed was developed in three stages, first one was a monitoring in real scale with aerobic sludge discards, another one performed in a pilot scale with anaerobic sludge discard, both generated in wastewater treatment plant (WWTP), and the third stage was a survey of operational information of some wedge wire floor sludge bed in operation in Brazil. The conventional sand drying bed is still the most used system in Brazil for dewatering and drying of sludge generated during sewage treatment in small and médium size WWTP. However, due to the increase in inspection by environmental agencies, increased demands for quality in treatment, high costs in management, as well as problems with final sludge drying efficiency, odors and bed maintenance, the companies have been looking for alternatives to new technologies, and even optimizations in existing beds. An alternative that has proven efficient in the dewatering of sludge is the modified sludge bed with wedge wire floor. However, there is still little experience with the dimensioning of the bed, its operation and efficiency because it is a technology that has not been used abroad and recently arrived in Brazil. Therefore, this research had as objective to evaluate the dewatering of sewage sludge in wedge wire bed in the drainage and drying phases. The drainage of the sludge was evaluated through the drainage flow after filtration in the wedge wire floor, the reduction of sludge volume in the bed and the characterization of the quality of the drained water. Drying was evaluated by increasing the total solid content of the sludge during the entire drying period. As it is a natural drying process, monitoring of the local climatic conditions was performed. The results were satisfactory for both aerobic and anaerobic sludge. In relation to the drainage, after one day from discharge in the bed, there was a reduction of around 90% of the volume for aerobic sludge and 70% for anaerobic sludge. However, the final solid content obtained in the drying varied according to the type of sludge, volume, solids application rate and climatic conditions. The best drying result for aerobic sludge was 95.3% of total solid in 36 days of drying, and for anaerobic sludge the maximum reached was 63.5% in 24 days, in different climate conditions.

The thesis is focused on the sludge management at root sewage treatment plants with focus on volum eis highest – sludge manahement. Sludge dewatering using sludge dryiing bed is still condemned designers mainly due to their lack of experience, while at the same time enforcing technologically complex solutions. Therefore, the thesis focuses on the break down balance hydrological equation sludge drying bed, which includes all parameters affecting water balance system. The result is a proposal not only design, but in particular a description of input data and the governing equations in software Reed-Bed, which is calibrated own operational results obtainde for the two sewage treatment plants (village Dražovice and Kotenčice). Reed-Bed software will perform sevetal functions: setting the ground area of sludge bed, investment costs required for the implementation of sludge bed, return on investment, the determination of moisture contene of sludge in the sludge bed and maximum lenght of the dewatering period with regard to wetland vegetation. The second largest item within sludge system creates biomass wetland plants, so work deals with possibilities biomass processing plant at the end of the growing season. Technological processing of biomass was tested on common reed, final product pellets for heating.

This Master’s Thesis deals with a question of the current methods of treatment of sewage sludge. The main objective is to compare the financial cost of conventional drying with solar drying. In the first part is described process of the treatment sludge and its disposal options. The Thesis also describes different methods of drying sewage sludge.

The master´s thesis deals with the problem of sewage sludge from wastewater treatment plants and their subsequent incineration. Main aim is compare some possibilities of the energy use of mechanically dewatered sewage sludge and sewage sludge with previous anaerobic pre-treatment for various levels of drying sludge.

Le séchage des boues d'épuration est un problème environnemental actuel, qui n'est pas suffisamment décrit dans la littérature. Par conséquent, ce travail représente une étude numérique des transferts de chaleur et de masse lors du séchage solaire des boues d’épuration. Cette boue est assimilée à un milieu poreux et exposée à un écoulement laminaire de convection forcée à l'intérieur d'un canal horizontal. Les transferts dans le canal et le milieu poreux sont décrits respectivement par les équations classiques de la convection forcée et par le modèle de Darcy-Brinkman-Forchheimer. Une méthode implicite aux différences finies est utilisée pour discrétiser le système d'équations différentielles régissant les transferts. Les systèmes algébriques obtenus sont résolus en utilisant les algorithmes de Gauss, Thomas et Gauss-Seidel. Afin de déterminer la vitesse de séchage, nous associons à ces équations un modèle de cinétique de séchage. Ce modèle est basé sur le concept de la courbe caractéristique. Nous avons particulièrement étudié les effets des conditions climatiques et des conditions relatives à la boue sur les évolutions spatio-temporelles des nombres caractéristiques des transferts ainsi que sur la cinétique de séchage. Le travail est complété par des simulations en utilisant des données météorologiques réelles de la région de Tataouine au sud de la Tunisie. Ces données ont subi un traitement statistique à l’aide de la méthode de Liu et Jordan afin de déterminer la journée type de chaque mois. L’étude de rentabilité du séchoir a montré que la période estivale est la période optimale pour le séchage
The drying of sewage sludge is a current environmental problem, not sufficiently described in the literature. Hence, the aim of this work is a numerical study of heat and mass transfers during solar drying of residual sludge. This sludge is assimilated to a porous medium and exposed to a forced convection laminar flow within a horizontal channel. The transfers in the channel and the porous medium are respectively described by the classic equations of forced convection and the Darcy-Brinkman-Forchheimer model. The implicit finite difference method is used to discretize the governing differential equation system. The algebraic systems obtained are solved using the Gauss, Thomas and Gauss-Seidel algorithms. To determine the drying rate, we associate a drying kinetics model. This model is based on the concept of the characteristic curve. We particularly studied the effects of climatic conditions (temperature, velocity and relative humidity of the ambient air as well as the solar radiation intensity) and the conditions relating to the sludge on the spatio-temporal evolutions of the transfers characteristic numbers as well as on drying kinetics. This work is completed by simulations using meteorological data from the Tataouine region in southern Tunisia. These data were statistically processed using the Liu and Jordan method to determine the typical day of each month. The rentability study of the dryer show that the summer period is the optimum period for drying

Cette thèse propose une approche hiérarchique du diagnostic des systèmes complexes par décomposition en sous-systèmes élémentaires de diagnostic puis agrégation de ceux-ci. Le chapitre 1 décomposition en sous-systèmes élémentaires de diagnostic puis agrégation de ceux-ci. Le chapitre 1 détaille la problématique du diagnostic en temps réel ainsi que celle des systèmes complexes. Il en propose une solution par décomposition hiérarchique et présente l'outil logiciel dialogs issu de ce concept. Il présente enfin un système complexe illustrant cette approche. La station d'épuration de Maxéville et son séchage thermique des boues. Les chapitres 2 et 3 abordent l'aspect modulaire de cette approche au travers de l'étape de génération de symptômes. Le chapitre 2 propose pour cela des méthodes de détection de défauts permettant, de générer des symptômes indépendants. Le chapitre 3 présente des techniques plus élaborées assurant également la localisation de défauts au travers d'ensemble de symptômes. La nécessité d'associer les résidus fournis par ces méthodes dans des niveaux de décision hierarchiquement supérieurs impose leur homogénéisation au moyen de tests de décision présentes chapitre 2. Le chapitre 4 développe les notions de hiérarchisation et d'agrégation de systèmes élémentaires au travers de deux méthodes de localisation de défauts, la décision structurée et la décision à objectifs multiples. Une troisième technique, la décision générique, permet de conclure quant à l'état du système complet

Cette étude porte sur l’influence de différents traitements sur les caractéristiques et l’évolution de la matière organique de boues de stations d’épuration (Step). Les échantillons étudiés proviennent de 3 stations municipales de la Vienne. Le premier volet développé au cours de l’étude a pour but la mise au point d’une méthode d’analyse qualitative et quantitative des constituants des boues de Step. Les résultats obtenus démontrent le potentiel de la thermochimiolyse-GCMS à caractériser, sans extraction préalable, la matière organique d’un échantillon brut. Le deuxième volet de cette thèse s’est intéressé à l’influence de différents traitements (séchages, accélérateur d’électrons et méthanisation) sur l’évolution de la matière organique. Ainsi, le séchage thermique provoque une fragilisation de la matière organique, le séchage solaire une complexification et les lits plantés de roseaux n’ont pas d’influence significative à court terme. L’application du procédé d’oxydation avancé sur une boue flottée a provoqué une acidification et des changements structuraux de la matière organique. Ainsi une faible dose (1,25 kGy) a conduit à une complexification de la matière organique alors qu’une plus forte dose (50 kGy) semble la fragiliser. La modification de la matière organique à l’issue du procédé de méthanisation concerne uniquement la fraction lipidique et notamment des acides gras
This study investigated the influence of different treatments on the characteristics and evolution of organic matter of municipal wastewater sludge. For this, three municipal wastewater treatment plants of Vienne department were sampled.The first phase developed during the study focused on the improvement of a method for qualitative and quantitative analysis of the sewage sludge’s constituents. The presented results demonstrate the strong potential of the thermochemolysis-GCMS to characterize, without extraction, the organic matter of a raw sample.The second part of this Ph.D has focused on the influence of various treatments (drying, electron beam and methanation) on the evolution of organic matter. Thus, the thermal drying causes weakening of the organic matter while the solar drying induces its complexification and reed beds induce no significant change. The application of an advanced oxidation process on a floated sludge caused acidification and structural changes of the organic matter. A low dose (1.25 kGy) led to more complex organic matter, while a higher dose (50 kGy) seems to weaken it. The changes in organic matter induced by anaerobic digestion mainly concerned the lipid fraction, in particular fatty acids

碩士
國立宜蘭大學
綠色科技學程碩士在職專班
104
The main solid waste is produced from the wastewater treatment plant (WWTP) where municipal wastewater collected by the public sewarage system then disposed through the procedures of the plant. There are sixty four public wastewater treatment plants under the authority of Construction and Planning Agency Ministry of the Interior, more than 200 tons waste sludge are produced every day with 75 to 80 % of water content from the operation plants. By taking Ludon Wastewater Treatment plant as an example, the average increasing influent amount is more than 2,000 CMD every year, and the amount of delivery sludge is about 1,600 tons which cost 9 millions TWD for disposal which takes more than 30% of whole operation cost. The most common method of sludge drying in Taiwan is Hot Air Drying, additionally, there are Vacuum Drying, Infrared Drying, Freeze Drying, etc. This study is concentrated on dyring sludge by Microwave Drying, and the influential factors are the energy of microwave, the volume of sludge, the micorwave time, the thickness of sludge¸and so on. In this study, the factors which might have influences on the efficiency of sludge drying are investigated individually. The result of experiment indicates that the water content could be ruduced from 80% to 25% through 9 minutes micorwave, while the microwave energy is 800W with 40 gram of sludge and 0.5 cm of sludge thickness. Furthermore, the water content could be reuced from 80% to 49.6% under the same condition, but only the sludge volume rises to 240 gram. The effect of Microwave Drying is outstanding. Besides, the consumption of energy during the process of microwave is also analyzed, it only cosumes 480,000J with 800W/240g (the rate of microwave/the volume of sludge). It shows the most optimal effect of energy-saving by the adoption of combination with high rate and high volume compared to other experimental parameters.

碩士
大同工學院
化學工程研究所
87
The drying of sewage sludge from CPT (Chinese Picture Tube Co.) was experimentally studied in a batch fluidized bed. Experiments were carried out in a 90mm I.D., 1.36m in height laboratory-scale fluidized bed to visualize the effects of superficial air velocity (1.18~1.35 Umf), inlet air temperature (30~60oC), bed temperature (50~80oC), initial moisture content of sludge (16.5~42.8%), weight ratio of glass beads to sludge (12~20) and particle sizes of sewage sludge (0.336~0.503 mm) on the drying characteristics. In this study, sewage sludge was fed to a fluidized bed with coarse particles being fluidized by hot inlet air, then the time variations of humidity and temperature of inlet and outlet air were measured under different operating conditions. The experimental results indicate that the maximum drying rate increases with increasing of superficial air velocity, inlet air temperature, bed temperature, weight ratio of glass beads to sludge but decreases with increasing the particle sizes. The empirical correlation for the maximum drying rate is proposed to fit the experimental data with a correlation coefficient of 0.95 and standard error of estimate of 0.18.

碩士
大同大學
化學工程研究所
90
The drying characteristics of sewage sludge from CPT (Chinese Picture Tube Co.) were experimentally studied in a continuous fluidized bed. Experiments were carried out in a 90mm I.D., 1.3m in height laboratory-scale fluidized bed to visualize the effects of superficial air velocity (1.13~1.46Umf), inlet air temperature (30~60oC), bed temperature (30~60oC), feeding rate of sewage sludge (0.83~1.33g/s) and static bed height (130~190 mm). Sewage sludge was continuously fed to a fluidized bed with glass beads being fluidized by hot inlet air, then the time variations of humidity and temperature of inlet and outlet air were measured under different operating conditions. The experimental results indicate that the drying degree increases with increasing superficial air velocity, inlet air temperature, bed temperature and static bed height, but with decreasing feeding rate of sewage sludge. The performance of the continuous fluidized bed dryer can be predicted from continuous dryer kinetics and the residence time distribution of exited sludge. The calculated outlet moisture contents are in agreement with the experimental data within 15% in this study.

碩士
南華大學
科技學院永續綠色科技碩士學位學程
106
In this study, the sewage treatment plant of Zhongye Industrial Zone was adopted as an example to evaluate the effectiveness of sludge drying treatment. The moisture content of the sludge before drying was 80 to 90%, and the drying temperature was set at about 50 degrees. After drying for 2 to 4 hours, the moisture content of the sludge dropped to about 30 to 50%. At the same time, the operating parameters in the drying process are recorded to calculate the energy consumption and cost required for the drying process and the processing costs saved after the reduction, and the cost-benefit assessment of the drying reduction is completed. 　　Sludge reduction is necessary based on the rise of sludge treatment cost. In this study, the benefits of sludge drying treatment are evaluated. The cost includes the setting cost and operating cost of the dryer, and the benefit is the sludge removal fee of weight reduction. The practical data of sewage treatment plant in Zhonghe Industrial Zone was used in this study. The cost includes the setup cost of N.T. 17.99 million, and the operating cost of N.T. 12,828 per day for the average electricity charge. The moisture content of sludge after drying is reduced by 42%, and the average weight can be reduced by 56.3%. Based on the average sludge treatment capacity 10.23 ton/day, the reduced weight is 5.63 ton/day. According to the sludge removal price N.T. 6,450 per ton, the daily benefit can be calculated as N.T. 24,317 per day. Assuming that the drying facility can be operated for 10 years, the total cost will be N.T. 167,980,760, and the benefit will be N.T.69,637,240. The profit-to-expenditure ratio is 24.12 Therefore, the drying sludge is worth promoting in the sewage treatment plant.

Ph.D. Thesis in Environmental Engineering, submitted to the Faculty of Science and Technology of University of Coimbra
Sewage sludge (SS) formed during the purification of urban effluents in wastewater treatment plants (WWTP) is produced in high quantities in Portugal (around 300 kt year-1 on a dry basis) and in all developed countries. Thus, the management of this waste is expensive due to the high moisture content (greater than 80%), transportation costs, and all the logistics to the final destination. The main constituents of WWTP sludge are water, biomass (microorganisms, including some pathogens), inorganic solids, fats, macronutrients (N, P, K), Ca, Mg, Fe, and minor quantities of potentially toxic metals (PTM) such as Cr, Ni, Cu, Pb, Zn, and Cd. Due to its high organic matter (OM) content and nutrients, its application in the soil is a possible management route. In the context of the circular economy, this thesis aimed to study the isothermal sludge drying process, aided by other industrial residues, with a view to agronomic recovery. The studies involved sludge from anaerobic digestion and various industrial residues (weathered coal fly ash collected in a landfill - CFA; green liquor dregs - GLD; eggshell - ES and rice husk - RH) used as adjuvants. Experimental tests were carried out by drying small cylinders with an initial moisture content of about 80% at different isothermal conditions (70, 85, 100, 115, and 130 ºC). After the initial physical and chemical characterization of several samples of sludge and adjuvants, multiple drying studies were performed. Sludge samples were mixed with different proportions of adjuvants, where the most used dosage was 0.15 g g-1 of SS (wet basis). Initially, the characterization of soil and sludge samples revealed that the concentration of PTM of the soil complies with the lowest constraints in at least 90% of the Portuguese territory. However, if more restrictive limits were adopted (such as those adopted in Sweden), the concentrations of Ni, Zn and Cd would hamper the application of sludge in the soil. The ecological risk assessment showed that the geoaccumulation index (Igeo) for Cd, Cu and Zn corresponds to a moderate to the high pollution level. However, the pollution index (PI) and the potential ecological risk index (PERI) revealed that there is no contamination, and the ecological risk is low for the six metals studied. Drying kinetics demonstrated that different periods could be identified: Period 0 (warm-up), Period I (free water removal) and Period II (interstitial water removal), which represent the heating phase, constant drying period, and non-linear drying period, respectively. The temperature increase led to faster drying. For example, the control sample at 70 °C required about 64 minutes to achieve a moisture ratio (MR) of 0.30, while at 130 °C the same dryness level was reached in approximately 17 minutes. The positive effect of the use of adjuvants on the diffusion coefficient (D_{eff}), for example at 100 ºC in Period I, compared to the control sample, was 1.11; 16 and 19%, for CFA, ES, and RH, respectively. However, GLD decreased the D_{eff} by about 7%. Additionally, the experimental drying data can be well described by the second Fick's Law (Period I) and by the thin-layer model (Period II). Regarding the properties of adjuvants, the acid neutralization capacity of GLD and ES played an important role in increasing the pH of the soil from 6.7 to 7.8 and 8.0, respectively. GLD was the only adjuvant that decreased the pathogenic microorganisms (86%), although it did not improve the drying process. Thus, the studies carried out allowed to identify three decisive parameters in the selection of an adjuvant for the drying process: reduction of pathogenic microorganisms, acid neutralization capacity, and influence on the germination index. Germination study with Lepidium Sativum L. (garden cress) indicated that the sludge mixed with CFA and ES reduces the phytotoxicity effect of the sludge, reduces the acidity and increases the OM content in the soil. The SS:adjuvant mixture reduced the concentration that induces 50% of inhibition - EC50 by 66%, 60% and 80% for CFA, GLD, and ES, respectively, when compared with the effect of the SS without any adjuvant. Additionally, the tests in pots with garden cress revealed that the effect of the sludge with and without the different adjuvants did not present a deleterious effect on the plants. Finally, through a multicriteria approach involving environmental, technical and economic aspects, it was possible to conclude that the sludge drying using GLD at 130 ºC is the best option in terms of adjuvant type and temperature. However, ES at 130 ºC and GLD at 70 ºC can also be considered. Therefore, the incorporation of these residues as SS drying adjuvants can bring environmental and social gains, in addition to promoting the value chain in new routes for waste management, thus closing the loop of these anthropogenic materials in the environment.
As lamas formadas na depuração de efluentes urbanos em Estações de tratamento de águas residuais (ETAR) são produzidas em elevadas quantidades em Portugal (em torno de 300 kt ano-1 em base seca) e em todos os países desenvolvidos. Devido ao elevado teor de humidade (superior a 80%), aos custos de transporte, e a toda a logística até ao destino final, a gestão destes resíduos é por isso dispendiosa. Os principais constituintes da lama de ETAR são a água, biomassa (microrganismos, incluindo alguns agentes patogénicos), sólidos inorgânicos, gorduras, macronutrientes (N, P, K), Ca, Mg, Fe e quantidades menores de metais potencialmente tóxicos (PTM) como por exemplo Cr, Ni, Cu, Pb, Zn e Cd. Devido ao seu elevado teor em matéria orgânica (OM) e nutrientes, a sua utilização no solo tem sido uma via possível para gerir este resíduo. No contexto da economia circular, esta tese teve como objetivo estudar o processo de secagem isotérmica de lama, coadjuvado com outros resíduos industriais, tendo em vista a valorização agronómica. Os estudos envolveram lamas de digestão anaeróbia, bem como diversos resíduos industriais (cinzas de carvão coletadas num aterro – CFA; Dregs de licor verde – GLD; casca de ovo – ES e casca de arroz – RH). Os ensaios foram realizados com recurso à secagem de pequenos cilindros com humidade inicial de aproximadamente 80%, para diferentes condições isotérmicas (70, 85, 100, 115, e 130 ºC). Após uma fase inicial de caracterização física e química de diversas amostras de lamas e dos adjuvantes, foram realizados múltiplos estudos de secagem. As amostras de lamas foram misturadas com diversas taxas de aditivos, sendo a mais utilizada 0,15 g g-1 de lama (base húmida). Inicialmente, o estudo da caracterização das amostras de solo e lama, revelou que a concentração de PTM do solo cumpre as restrições mais baixas em cerca de 90% do território português, e que os limites impostos à lama na legislação portuguesa não foram ultrapassados em nenhuma amostra. No entanto, se fossem adotados limites mais restritivos (como por exemplo os praticados pela Suécia), as concentrações de Ni, Zn e Cd poderiam ser impeditivas para aplicar lama ao solo. A avaliação do risco ecológico mostrou que o índice de geoacumulação (Igeo) para Cd, Cu e Zn corresponde a um nível de poluição moderado a alto. No entanto, o índice de poluição (PI) e o índice potencial de risco ecológico (PERI) revelaram que não há contaminação e o risco ecológico é baixo para os seis metais estudados. A cinética de secagem demonstrou que podem ser identificados diferentes períodos de secagem: Período 0 (warm-up), Período I (free water removal) e Período II (interstitial water removal), os quais representam a fase de aquecimento, período de secagem constante e o período não linear de secagem, respetivamente. O aumento na temperatura levou a uma secagem mais rápida. Por exemplo, a amostra de controlo a 70 °C exigiu cerca de 64 minutos para atingir uma razão de humidade (MR) de 0,30, enquanto que a 130 °C o mesmo nível de secagem foi alcançado em aproximadamente 17 minutos. O efeito positivo do uso dos adjuvantes no coeficiente de difusão (D_{eff}), por exemplo a 100 ºC, no Período I, face à amostra controlo, foi 1,11; 16 e 19 %, para o CFA, ES e RH, respetivamente. Entretanto, o uso de GLD diminuiu o D_{eff}\ em ~ 7%. Também foi possível verificar que os dados experimentais da secagem podem ser bem descritos pelo modelo baseado na segunda Lei de Fick (Período I) e pelo modelo da fina-camada (Período II). Relativamente às propriedades dos adjuvantes, a capacidade de neutralização ácida do GLD e da ES assumiu papel importante no aumento do pH do solo de 6,7 para 7,8 e 8,0, respetivamente. O GLD foi o único adjuvante que influenciou na diminuição dos microrganismos patogénicos (86%), embora não tenha melhorado o processo de secagem. Assim, os estudos realizados permitiram identificar três parâmetros decisivos na escolha de um adjuvante para o processo de secagem: diminuição de microrganismos patogénicos, capacidade de neutralização ácida e influência no índice de germinação. O estudo de germinação com Lepidium Sativum L. (agrião de jardim) indicou que a lama misturada com CFA e com ES reduz o seu efeito fitotóxico e a acidez e aumenta o conteúdo de MO no solo. A mistura lama:adjuvante reduziu a concentração que induz 50% de inibição - EC50 em 66%, 60% e 80% para CFA, GLD e ES, respetivamente, quando comparado com o efeito da lama sem adição de qualquer adjuvante. Adicionalmente, os testes em vasos com agrião de jardim revelaram que a lama com e sem os diferentes adjuvantes não apresenta efeito deletério para as plantas testadas. Finalmente, através de uma abordagem multicritério envolvendo aspetos ambientais, técnicos e económicos, foi possível concluir que a secagem de lama utilizando GLD a 130 ºC é a melhor opção em termos de adjuvante e temperatura. No entanto, ES a 130 ºC e GLD a 70 ºC também podem ser opções consideradas. Assim, a incorporação destes resíduos como adjuvantes de secagem de lamas pode trazer ganhos ambientais e sociais e promover a cadeia de valor, que se traduz em novas rotas de gestão de resíduos, fechando o ciclo destes materiais antropogénicos no ambiente.
Federal Institute of Education, Science, and Technology of Brasília - IFB, Brazil, Campus Ceilândia

碩士
國立中央大學
環境工程研究所在職專班
103
Various sludge treatment processes including thickening, digestion, and dewatering have been implemented to reduce the amount of sludge to be disposed of. However, due to the lack of landfill capacity and high water content of the dewatered sludge, landfilling is not a good way and better sludge reduction approach should be applied. Sewage sludge, a product of the domestic wastewater treatment process, is the main source of organic sludge. The water content of sludge without treatment is about 98%, and with dewatering process the water content could be reduced to 80-90%. To further reduce the amount of sludge, methods such as sun-drying or heat exchanging could be implemented. This research examines the benefit of sludge drying process for a wastewater treatment plant in Northern Taiwan. The results showed that sludge drying method could reduce water content from 85.4% to 5.9%, thus reduced sludge from 140 tons/day to 22 tons/day. This indicates a significant reduction in sludge transportation from 8 loads to 2 loads daily, meanwhile the odor from the sludge can be eliminated by reducing the water content to below 30%. On the other hand, sludge drying enables recycle for various purposes depending on its water content. The wastewater treatment plant, with benefits from applying the sludge drying process, could set an example for other treatment plants to follow. Thus, the obiectives of reducing the amount of waste, relieving the storage problems of landfills, reducing the pollution from waste transportation and odor, and recycling the sludge for various uses can be achieved.

Dissertação de Mestrado Integrado em Engenharia do Ambiente apresentada à Faculdade de Ciências e Tecnologia
O presente trabalho tem como objetivo o estudo das características e quantidade de lama produzida nas ETAR em Portugal, e a análise dos tipos de tecnologias existentes para secagem de lama, de modo a minimizar a humidade e favorecer o processo de gestão, tendo por finalidade a sua valorização. É apresentada e analisada a produção e o tratamento das lamas (urbanas e industriais) ao nível da ETAR, e as suas principais características. As obrigações legais dos produtores e operadores de lamas e as diferentes opções de valorização são analisadas, com ênfase para a valorização agrícola, sendo indicadas as concentrações máximas de metais pesados e substâncias tóxicas aceitáveis.Neste estudo é realizada uma revisão das tecnologias de secagem de lamas porsistemas indiretos, diretos e combinados, incluindo os sistemas de secagem baseados no aproveitamento da energia solar. É também efetuada uma revisão dos assuntos relacionados com a taxa de secagem, alterações superficiais, dimensionais e reológicas das lamas. De modo analisar a influência e eficiência dos diferentes sistemas de secagem procedeu-se à análise das tecnologias correntes e resultados de estudos experimentais de secagem de lamas.Os resultados mostram que a superfície específica da lama afeta a cinética de secagem, devido à formação de uma crosta superficial que dificulta a secagem de lama, e que o aumento da cinética de secagem e redução do tempo de secagem requer altas temperaturas do fluido de secagem. Os secadores que promovem a agitação ou movimentação das lamas ao longo do processo são mais eficientes e permitem reduzir o consumo energético e o tempo de secagem das lamas, se adicionalmente usam uma baixa temperatura de operação ainda é possível reduzir mais os custos de operação. Mesmo assim, tendo em conta que a secagem térmica consome muita energia, para diminuir o consumo é recomendável o uso de energias renováveis (solar, biogás).Com este estudo conclui-se que a seleção de um de secador depende do tipo de lama, destino final e tipos de energia disponíveis.
The aim of this work is the analysis of the characteristics and quantity of sewage sludge produced in Portuguese’s WWTP and the study of the different types of technologies for sewage sludge drying used to minimise moisture and favourise the management for the purpose of valorisation. The production and treatment of sludge (urban and industrial) at WWTP and the main characteristics of sewage sludge delivered are presented and analysed.The responsibilities of producers and operators of sewage sludge according the legislation is described and the different options of valorisation are analysed, with emphasis on agricultural valorisation and the maximum concentrations of heavy metals and acceptable toxic substances allowed are shown.A review of sewage sludge drying technologies currently used, based in indirect,direct and combined systems, as also drying systems based on solar energy used is carry out.The drying rate, surface area, volume and rheological changes of sewage sludge during drying process are also analysed. The design and efficiency of the different types of dryers and the results of experimental studies are analysed. The results show that the influence of specific surface of the sewage sludge on the drying kinetic due to the formation of a surfasse crust, which makes sewage sludge drying difficult and show also that to increasing drying kinetics and reducing drying time requires high temperatures. Dryers that promote agitation or movement of sewage sludge are more efficient and allow the reduction of energyconsumption and drying time. In addition, the dryers that operate at low temperature allows to increasing the reduction of operational costs. Nevertheless, thermal drying usually consumes a significant amount of energy, so to reduce energy consumption it is suitable to use renewable energy (solar, biogas).In conclusion, the selection of sewage sludge dryer depends on the type ofsewage sludge, final destination and type of energy available.

Bibliography: leaves 256-275.
xx, 275 leaves : ill., map ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Plant Science, 1997

Dissertação de Mestrado Integrado em Engenharia do Ambiente apresentada à Faculdade de Ciências e Tecnologia
A elevada quantidade de lamas produzidas durante o tratamento de águas residuais em ETAR tornou-se um problema global a nível ambiental. No contexto da economia circular, é necessária uma estratégia eficaz na gestão destes resíduos tal como a valorização energética (através de incineração) ou agrícola (com ou sem compostagem), devendo evitar-se o mais possível o aterro. A valorização agrícola tem sido uma estratégia cada vez mais utilizada, uma vez que as lamas podem contribuir para a fertilização do solo devido aos elevados teores de matéria orgânica e nutrientes (N e P). Neste caso, é de extrema importância avaliar o grau de estabilidade das lamas, sendo este o principal objetivo deste estudo. Para a avaliação do grau de estabilidade recorreu-se a testes respirométricos estáticos em Oxitop®, com base no consumo de O2. Estes testes foram realizados em matrizes sólidas e líquidas onde foram analisadas lamas provenientes de digestão anaeróbia (DA) e de sistemas de lamas ativadas (LM). Inicialmente, as amostras foram caracterizadas em termos de sólidos totais, humidade e sólidos voláteis, sendo estes dois últimos os parâmetros mais relevantes numa análise respirométrica. Avaliou-se o uso de cinzas de biomassa (CB) como adjuvante de secagem, onde estas demonstraram melhorar o processo aquando da incorporação de 0,05, 0,15 e 0,20 g CB/g amostra. A análise respirometria em matrizes sólidas demonstrou ser bastante complexa, conforme vem sendo discutido na literatura, uma vez que não são consensuais as condições ótimas de realização das análises. De todos os parâmetros analisados em matriz sólida, o que apresentou maior influência no resultado final foi a humidade. Através dos testes em matriz aquosa, verificou-se que as lamas DA (OUR = 56,99 mmol O2 g MO-1 h-1) são mais estáveis que as LM (OUR = 71,37 mmol O2 g MO-1 h-1). Para além disso, a secagem da lama a 100 ºC com 0,15 g CB/g amostra demonstrou ser eficiente para estabilizar ambos os tipos de lama abaixo do limite para uma matriz ser considerada estável em termos de matéria orgânica (50 mmol O2 kg MO -1 h -1). Por fim, foi avaliado o potencial agronómico dessa lama com diferentes tratamentos, onde a secagem a 100 ºC com 0,15 g CB/g amostra não só afetou positivamente os parâmetros de crescimento das plantas, mas também corrigiu o pH do solo para a região neutra.
The high amount of sludge produced during wastewater treatment at WWTP has become an environmental problem. In the circular economy context, an effective strategy in the management of this waste is needed, such as energetic valorization (incineration) and agricultural recovery (with or without composting). Agricultural valorization has been widely used as a management strategy due to its high levels of organic matter and nutrients (N and P) that can contribute to soil fertilization. In this case, the level of sludge stability is extremely important, which is the main objective of this study. Respirometry tests based on the consumption of O2 have been performed with an Oxitop® to assess the degree of stability. These tests were carried out in solid and liquid matrices where sludge from anaerobic digestion (AD) and activated sludge systems (LM) were analyzed. Initially, the samples were characterized in terms of total solids, moisture content, and volatile solids, with the last two being the most important parameters in this analysis. Biomass ash (CB) was evaluated as a drying agent and the incorporations of 0.05, 0.15, and 0.20 g CB/g sample were shown to improve the process. The respirometry in solid matrices proved to be quite complex, as already discussed in the literature, since the optimal operation conditions are not consensual. However, moisture revealed to be the parameter with the greatest influence on the result. Through tests in an aqueous matrix, it was found that DA (OUR = 56.99 mmol O2 g MO-1 h-1) sludge is more stable than LM (OUR = 71.37 mmol O2 g MO-1 h-1). In addition, drying the sludge at 100 ºC with 0.15 g CB/g sample proved to be efficient in stabilizing both types of sludge below the stability limit. Finally, the agronomic potential of sludge was evaluated with different treatments, where the sample dried at 100 ºC with 0.15 g CB/g sample showed not only positive effect in the plant growth parameters, but also corrected the soil pH for the neutral region.

Cette étude porte sur l’influence de différents traitements sur les caractéristiques et l’évolution de la matière organique de boues de stations d’épuration (Step). Les échantillons étudiés proviennent de 3 stations municipales de la Vienne. Le premier volet développé au cours de l’étude a pour but la mise au point d’une méthode d’analyse qualitative et quantitative des constituants des boues de Step. Les résultats obtenus démontrent le potentiel de la thermochimiolyse-GCMS à caractériser, sans extraction préalable, la matière organique d’un échantillon brut. Le deuxième volet de cette thèse s’est intéressé à l’influence de différents traitements (séchages, accélérateur d’électrons et méthanisation) sur l’évolution de la matière organique. Ainsi, le séchage thermique provoque une fragilisation de la matière organique, le séchage solaire une complexification et les lits plantés de roseaux n’ont pas d’influence significative à court terme. L’application du procédé d’oxydation avancé sur une boue flottée a provoqué une acidification et des changements structuraux de la matière organique. Ainsi une faible dose (1,25 kGy) a conduit à une complexification de la matière organique alors qu’une plus forte dose (50 kGy) semble la fragiliser. La modification de la matière organique à l’issue du procédé de méthanisation concerne uniquement la fraction lipidique et notamment des acides gras
This study investigated the influence of different treatments on the characteristics and evolution of organic matter of municipal wastewater sludge. For this, three municipal wastewater treatment plants of Vienne department were sampled.The first phase developed during the study focused on the improvement of a method for qualitative and quantitative analysis of the sewage sludge’s constituents. The presented results demonstrate the strong potential of the thermochemolysis-GCMS to characterize, without extraction, the organic matter of a raw sample.The second part of this Ph.D has focused on the influence of various treatments (drying, electron beam and methanation) on the evolution of organic matter. Thus, the thermal drying causes weakening of the organic matter while the solar drying induces its complexification and reed beds induce no significant change. The application of an advanced oxidation process on a floated sludge caused acidification and structural changes of the organic matter. A low dose (1.25 kGy) led to more complex organic matter, while a higher dose (50 kGy) seems to weaken it. The changes in organic matter induced by anaerobic digestion mainly concerned the lipid fraction, in particular fatty acids