This master thesis gives an account for various aeration schemes that are utilized in conventional activated sludge treatment process in a wastewater treatment plant. By altering between different aeration schemes, the project aimed at reducing energy consumption along with maintaining the treatment performance at the plant. A series of experiments on the treatment performance over several different aeration schemes thus has been conducted on site at Solviken in Mora, Sweden. The project is basically a case study where no parameters were manually controlled except for the aeration schemes at the plant. Energy consumption reduction is logically relative to the ratio between aeration and non-aeration intervals. Several criteria were tested in regards to the treatment performance, including pH value, organic matters, phosphorus substances and microorganisms. The study has come up with a superior aeration scheme for the plant, as well as indicated processes that can be improved at the plant.

Vid vattenrening produceras slam som restprodukt. Slam innehåller en stor mängd ämnen, såsom metaller, medicinrester och olika näringsämnen. I Sverige produceras flera hundra tusen ton årligen. Innehållet måste hanteras, men hur görs det idag och hur kommer det att hanteras i framtiden. Vanligast idag är att återvinna fosfor och kväve genom att sprida slam som gödning inom jord och skogsbruk. Däremot metaller som finns i slam utvinns inte idag, även om det vore värdefullt ur miljösynpunkt.  Denna litteraturstudie beskriver hur slamhantering ser ut idag, med fokus på Sverige. Därefter beskrivs forskningsläge och möjlig framtida utveckling i hantering. Slamhantering är problematisk ur flera aspekter. Slamhantering behöver hantera följande svårigheter: En logistisk aspekt är de stora volymer som behöver hanteras och att de produceras på många olika platser.Forskning på konsekvenser av slamspridning är relativt liten. Det gäller den påverkan som medicinrester, tungmetaller och andra ämnen utgör.Vilka utvinningsbara ämnen ska prioriteras, eftersom metoder för utvinning ställer maximerad utvinning av gödning i motsats till maximerad utvinning av metaller. / When purifying water, sludge is produced as a residual product. Sludge contains lots of different substances, such as metals, medical waste and different nutrients. In Sweden there is many hundred thousands of tons of sludge produced annually. The content must be managed, but how is it handled today and how will it be managed in the future. Commonly today phosphorus and nitrogen recycles by spreading sludge as fertiliser in agriculture and forestry. Metals in sludge is not recycled, even if it would be positive from an environmental point of view. This literature study describes how sludge treatment is today with a focus in Sweden. Then it describes the current state of research and possible future development in management. Sludge handling is problematic from many different aspects. Sludge treatment must have to address these challanges: One logistic aspect is that there are great volumes that needs to be handled and that it is produced in many different places. The research in consequences of sludge spreading is a relatively small base. That goes for the influence of medical waste, heavy metals, and other substances in sludge. What recyclable substances needs to be prioritised, since the methods of extraction puts the maximal extraction of fertiliser against the maximised extractions of metals

Hydrothermal carbonisation (HTC) could form the basis for rendering human faecal wastes safe whilst at the same time generating a carbon-rich material (hydrochar) and providing prospects for the recovery of energy. The work presented here has an objective of the search for optimal conditions for the HTC conversion of human faecal waste. Primary sewage sludge (PSS) and synthetic faeces (SF), of various moisture contents, were used as feedstocks to investigate the kinetics of decomposition of solids during HTC over a range of reaction times and temperatures. Decomposition was found to follow first-order kinetics, and the corresponding activation energies were obtained. Temperature was of primary importance to influence solid decomposition. Higher temperatures resulted in higher solids conversion to hydrochar. The energy contents of the hydrochars from PSS carbonised at 140 200oC for 4 h ranged from 21.5 to 23.1 MJ kg 1. Moisture content was found to affect the HTC process and feedstocks, with higher initial moisture contents resulted in lower hydrochar yields. The effect of reaction conditions on the characteristics of the hydrochar, liquid and gas products from HTC of faecal material, and the conditions leading to optimal hydrochar characteristics were investigated using a Response Surface Methodology (RSM). Models were developed here which could aid in the identification of reaction conditions to tailor such products for specific end uses. The results showed that the amount of carbon retained in hydrochars decreased as temperature and time increased, with carbon retentions of 64 77% at 140 and 160oC, and 50 62% at 180 and 200oC. Increasing temperature and reaction time increased the energy content of the hydrochar from 17 19 MJ kg 1 but reduced its energy yield from 88 to 68%. HTC at 200oC for 240 min resulted in hydrochars suitable for fuel, while carbonation at 160oC for 60 min produced hydrochars appropriate for carbon storage when applied to the soil. Theoretical estimates of methane yields resulting from subsequent anaerobic digestion (AD) of the liquid by-products are presented, with the highest yields obtained following carbonisation at 180oC for 30 min. In general, HTC at 180oC for 60 min and 200oC for 30 min resulted in hydrochars having optimal characteristics, and also for obtaining optimal methane yields. Maillard reaction products were identified in the liquid fractions following carbonisations at the higher temperatures. It was also found that the TOC, COD and BOD of the liquid products following HTC increased as the reaction temperature and time were increased and that these would require further treatment before being discharged. The results indicated that the gaseous phase following HTC contained carbon dioxide, nitrogen dioxide, nitric oxide, ammonia, and hydrogen sulphide indicating that additional treatment would be required before discharge to the atmosphere. In order to identify the optimum conditions leading to greater filterability of slurry resulted from HTC, the effects of reaction temperature and time on the filterability of PSS and SF slurries were investigated and optimised using RSM. It was shown that filterability improved as the reaction temperature and time at which the solids were carbonised was increased, with the best filtration results being achieved at the highest temperature (200°C) and longest treatment time (240 min) employed here. The specific cake resistance to filtration of the carbonised slurries was found to vary between 5.43 x 1012 and 2.05 x 1010 m kg 1 for cold filtration of PSS, 1.11 x 1012 and 3.49 x 1010 m kg 1 for cold filtration of SF, and 3.01 x 1012 and 3.86 x 1010 m kg 1 for hot filtration of SF, and decreased with increasing reaction temperature and time for carbonisation. There was no significant difference in specific resistance between cold and hot filtration of SF. The RSM models employed here were found to yield predictions that were close to the experimental results obtained, and should prove useful in designing and optimising HTC filtration systems for generating solids for a wide variety of end uses. Mass and energy balances of a semi-continuous HTC of faecal waste at 200oC and a reaction time of 30 min were conducted and based on recovering steam from the process as well energy from the solid fuel (hydrochar) and methane from digestion of the liquid by-product. The effect of the feedstock solids content and the quantity of feed on the mass and energy balances were investigated. Preheating the feed to 100oC using heat recovered from the process was found to significantly reduce the energy input to the reactor by about 59%, and decreased the heat loss from the reactor by between 50 60%. For feedstocks containing 15 25% solids (for all feed rates), energy recycled from the flashing off of steam and combustion of the hydrochar would be sufficient for preheating the feed, operating the reactor and drying the wet hydrochar without the need for any external sources of energy. Alternatively, for a feedstock containing 25% solids for all feed rates, energy recycled for the flashing off of steam and combustion of the methane provides sufficient energy to operate the entire process with an excess energy of about 19 21%, which could be used for other purposes.

Avloppsslam innehåller näringsämnen, som bör återföras till naturen för att skapa ett så kallat näringskretslopp. Genom att optimera hygieniseringen av avloppsslam med effektivare behandlingsmetod kan avloppsslam bli mer lämpligt att avsättas ur ett bättre ekonomiskt- och miljömässigt perspektiv. Syftet med arbetet var att undersöka och bedöma om effektiviseringav befintlig slambehandling är möjlig för att uppnå tillräcklig hygienisering. Utifrån den effektiviserade slambehandlingsmetoden utreda möjliga avsättningsalternativ som lämpar sig bäst för avloppsslammet i Avesta kommun. En litteraturöversikt utfördes för att öka kunskapen och förståelsen av avloppsslam, desshantering och avsättning. Fallstudien är utformad med kvalitativ metod och informationen har inhämtats från vetenskapliga artiklar, myndigheter, rapporter, examensarbeten och personligkontakt som komplement för att erhålla en god förståelse. Uppgradering av mesofil rötning av avloppsslam vid 37 °C till termofil rötning, 55 °C – 65 °C innebär förhöjd temperatur; det kräver mer energi och ökade energikostnader. Komponenter av den mesofila rötningsprocessen kommer att behöva uppgraderas eller bytas ut och därför tillkommer extra kostnader som också behöver ses över. Fördelarna med termofil rötning inkluderar kortvariga uppehållstider, mindre rötkammare och slammet blir tillräckligt hygieniserat. Ett framtidsscenario är framtaget utifrån effektiviserad slambehandling där två avsättningsalternativ är mest lämpliga för avloppsslammet i Avesta kommun. Gödsel till produktiv mark är ett av de föreslagna alternativ som tillåter fosforn återvinnas och återanvändas. Om inte termofil rötning som effektivisering hade erhållit tillräcklig hygienisering borde andra komplementerande processer ha införts, exempelvis komposteringstrumma eller pastörisering. En fullständig kostnadsjämförelse mellan befintlig slambehandlingsmetod och mer effektiviserad slambehandlingsmetod är dock nästan omöjlig att utföra då alla kostnader beror på val av komponenter och faktorer. Denna fallstudie bidrar med ett underlag som kan ge större möjligheter för Avesta Vatten och Avfall AB att välja den mest lämpliga avsättningen för avloppsslammet i Avesta kommun i framtiden. / Sewage sludge contains nutrients, which should be returned to nature to create a so-called nutrient circulation. By optimizing sanitisation of sewage sludge with effective treatment methods, sewage sludge can be more appropriately disposed from a better economic- and environmental perspective. The aim of this work was to investigate and judge the efficiency of existing sludge treatment is possible to achieve a sufficent sanitation. Based on the streamlined sludge treatment method investigate the disposal options that is best suited for sewage sludge in Avesta town. A literature review was conducted to increase the knowledge and understanding of sewage sludge, its treatment and disposal. The case study is formed with qualitative method and information which has been collected from the scientific articles, authorities, reports, theses and personal contact as a complement to obtain a good understanding. Upgrading of mesophilic digestion of sludge at 37 ° C to thermophilic digestion at 55 ° C - 65 ° C means increased temperature; this requires more energy and hence increases energy costs. Components of the mesophilic digestion process need to be upgraded or replaced and therefore additional costs should also be considered. The advantages of the thermophilic digestion include short residence time, smaller digester and sludge becomes sufficiently disinfected. A future scenario is developed based on more efficient sludge treatment where two disposal options are most appropriate for the sewage sludge in Avesta town. Returning digestate to productive land is one of those suggested alternatives that allows phosphorus to be recovered and recycled. If not thermophilic digestion as streamlining is not effective enough for sufficient sludge sanitation, other complementary processes have to be introduced, for instance, composting drum or pasteurization. A full cost comparison between the existing sludge treatment and more efficient sludge treatment method is, however, almost impossible to be performed when all costs depend on the choice of components, factors and so on. This case study contributes with first-hand information that can provide greater opportunities for Avesta Vatten och Avfall AB to select the most appropriate options for sewage sludge disposal in Avesta town in the future.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In water treatment plants (WTP) the solid waste generation is considered very high. The sludge from WTP have their own characteristics, which depend mainly on the captured water quality, the chemicals used in the treatment and cleaning method of the settling basins. The sludge characterization is carried out in laboratory tests before using any type of product or method of treatment. The thickening is one of the most important stages of sludge treatment and it aims to decrease the volume and increase the solids concentration. In this work it was evaluated the performance of the sludge thickening of the WTP São Gabriel RS (Brazil) by sedimentation and flotation with dissolved air (DAF). Sludge samples were collected in two sampling campaigns, which it was characterized and used in the thickening studies. Five different types of polymers (among cationic, anionic and nonionic) were employed, and those which resulted in lower residual turbidity of the clarified water after flocculation, were used in thickening studies. The parameters evaluated after thickening were: remaining turbidity of the clarified water; solids concentration; settling rate (velocity); and resistance to filtration. In the quantitative characterization sludge it was evident in the sludge mass production by means of an empirical equation of 11.8 tons / month and 11.1 tons / month by in loco measurement. Qualitatively the sludge had low biodegradability, and it was classified as waste Class II A - Not Inert , according to the Brazilian Regulation NBR 10.004 (2004). In the thickening studies with different dosages of cationic and anionic polymers (very low density charge - MB) for the settling tests, and only the cationic polymer-MB showed good results for the DAF. In order to compare settling and flotation thickening processes it was found that the remaining turbidity of the clarified water had lower values by treating by DAF. The higher solids concentrations were found in the sludge thickened by sedimentation, to the dosages of 1.0 and 1.5 mg cationic pol. - MB/g SST (7.05 and 7.10%) and 0.25 mg anion pol./g SST (7.04%). Settling rates of the thickened sludge by DAF 50% was higher than the other treatments, but showed no statistic difference to the different polymer dosages. In particular sludge strength tests gave the lowest value for the treatment by sedimentation for dosage of 4.5 mg pol. cationic - MB / g SST (9.0 x 1012 m.kg-1). In conclusion, the use of polymers aided the sludge thickening both in sedimentation as in the DAF thickening processes. However it is necessary prior to the decision making in choosing the kind of the thickening process, to evaluate the polymer type and dosage, determine what will be the subsequent processes of sludge treatment, and which parameters are most relevant according to the WTP. Yet it must be considered the cost and available staff before opting for the use of sludge thickening by sedimentation or DAF. / Em estações de tratamento de água (ETAs) ocorre uma geração elevada de resíduos sólidos. Os lodos de ETAs apresentam características próprias, que dependem principalmente da qualidade da água captada, dos produtos químicos utilizados no tratamento e método de limpeza dos decantadores. A caracterização do lodo é feita com ensaios em laboratório antes de empregar qualquer tipo de produto ou método de tratamento nos resíduos. O adensamento constitui umas das fases mais importantes do tratamento do lodo, pois visa a diminuição do volume e máxima concentração de sólidos. Neste trabalho foi avaliado o desempenho do adensamento do lodo de decantadores da ETA de São Gabriel RS (Brasil), por meio de sedimentação e flotação a ar dissolvido (FAD). Amostras de lodo foram coletadas em duas campanhas de amostragem, sendo este, após caracterizado, utilizado nos ensaios de adensamento. Avaliou-se a utilização de cinco tipos de polímeros (catiônico, aniônico e não-iônico), e aqueles que resultaram em menor turbidez remanescente da água clarificada, após a floculação, foram utilizados nos ensaios de adensamento. Os parâmetros avaliados após o adensamento foram: turbidez remanescente da água clarificada; concentração de sólidos; velocidade de clarificação; e resistência a filtração. Na caracterização quantitativa do lodo foi evidenciada a produção de massa de lodo, por meio de equação empírica, de 11,8 toneladas/mês e de 11,1 toneladas/mês por meio de medição in loco. Qualitativamente o lodo apresentou baixa biodegradabilidade, e quanto à classificação segundo a NBR 10.004 de 2004, o lodo foi classificado como resíduo Classe II A Não Inerte. Nos ensaios de adensamento com diferentes dosagens dos polímeros aniônico e catiônico (muito baixa densidade da carga MB) nos ensaios de sedimentação, e para a FAD apenas o polímero catiônico MB. Na comparação dos tratamentos verificou-se que a turbidez remanescente da água clarificada obteve menores valores por meio do tratamento por FAD. As maiores concentrações de sólidos foram encontradas no lodo adensado por sedimentação, para as dosagens de 1,0 e 1,5 mg pol. catiônico - MB/g SST (7,05 e 7,10%) e 0,25 mg pol. aniônico/g SST (7,04%). A velocidade de clarificação do lodo adensado por FAD 50% foi superior aos demais tratamentos, mas não apresentou diferença estática para as distintas dosagens. Nos ensaios de resistência específica do lodo obteve-se menor valor para o tratamento por sedimentação para a dosagem de 4,5 mg pol. catiônico - MB/g SST(9,0E+12 m.kg-1). Conclui-se que a utilização dos polímeros auxiliou no adensamento do lodo, tanto na sedimentação quanto na FAD. Contudo faz-se necessário antes da tomada de decisão na escolha do processo de adensamento, do tipo de polímero e dosagem utilizada, determinar quais serão os processos subsequentes de tratamento do lodo, e quais os parâmetros são mais relevantes dentro da realidade da ETA. Ainda deve-se considerar os custos e a disponibilidade de pessoal qualificado antes de optar pelo emprego do adensamento do lodo por sedimentação ou por FAD.

Submitted by Valquíria Barbieri (kikibarbi@hotmail.com) on 2018-04-05T20:50:38Z No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) / Approved for entry into archive by Jordan (jordanbiblio@gmail.com) on 2018-04-23T16:57:12Z (GMT) No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) / Made available in DSpace on 2018-04-23T16:57:12Z (GMT). No. of bitstreams: 1 DISS_2014_Joab Almeida da Silva.pdf: 3033730 bytes, checksum: 4a0f1680715be7f6554110dafd84ae3e (MD5) Previous issue date: 2014-11-04 / O lodo de esgoto é um resíduo perigoso de acordo com a NBR 10.004/04, e quando mal gerenciado, pode afetar de modo adverso não apenas o meio ambiente como a saúde pública, por ser agente de propagação de doenças. Por outro lado, o biossólido obtido a partir do lodo de esgoto doméstico é considerado um ótimo biofertilizante devido à sua composição, por ser rico em matéria orgânica, nitrogênio e fósforo. Este trabalho teve como objetivo avaliar o potencial do lodo oriundo de fossas/tanques sépticos domiciliares da Região Metropolitana de Cuiabá (RMC) para disposição final em solos agrícolas. O experimento de leito de secagem natural foi desenvolvido em um laboratório terceirizado com o objetivo de avaliar a qualidade do lodo coletado em fossas sépticas dos bairros Dom Aquino, Coxipó da Ponte, Morada da Serra, Boa Esperança e Jardim Universitário e lodo transportado por veículos limpa-fossa. O experimento seguiu o mesmo procedimento de tratamento do lodo nas estações de tratamento de esgoto. Após esse processo, o material foi higienizado com cal virgem a 50% da base seca e submetido a um período de maturação de 30 dias, posteriormente foram submetidas a análises laboratoriais. Os parâmetros analisados foram com relação à estabilidade, a metais pesados e organismos patogênicos resistentes. Os resultados foram comparados com os padrões da legislação vigente. Também foram utilizadas técnicas de geoprocessamento e sistemas de informações geográficas (SIG) com objetivo de identificar as áreas potencialmente aptas para recebimento de biossólido. De acordo com os resultados obtidos, o leito de secagem de exposição natural apresentou eficiência na desidratação e estabilização do lodo, atingindo níveis menores que 10% de umidade e a relação entre sólidos voláteis e totais menores que 0,10; com relação às concentrações de elementos-traços de metais analisadas, todas as amostras de biossólidos apresentaram teores inferiores aos valores máximos permitidos pela Resolução CONAMA 375/06, inclusive a amostra do caminhão limpa-fossa, que apresentou os teores mais elevados dos parâmetros analisados; após a higienização do lodo, o material apresentou qualidade de biossólido classe A em relação à concentração de organismos patogênicos; por fim, o estudo do meio físico viabilizou a disposição do biossólido em pelo menos 75,30% (2.664,23 km²) da área do município, enquanto que 24,70% (873,93km²) apresentam restrições por se tratar de locais não recomendados para à aplicação desse tipo de material. / The sewage sludge is a hazardous waste according to NBR 10004/04, and when poorly managed, can adversely affect not only the environment and public health, to be the spread of disease agent. On the other hand, the sludge obtained from the sewage sludge is considered a great biofertilizer due to its composition, to be rich in organic matter nitrogen and phosphorus. This study aimed to evaluate the potential of the sludge coming from tanks / household septic tanks in the metropolitan region of Cuiabá (RMC) for final disposal on agricultural soils. The experiment of natural drying bed was developed in an outsourced laboratory with the aim of evaluating the quality of the sludge collected in pits neighborhoods Dom Aquino, Coxipó da Ponte, Morada da Serra, Boa Esperança and Jardim Universitário of septic tanks and transported by vehicles clean-pit. The experiment followed the same procedure in the treatment of sludge from sewage treatment plants. After this process, the material was sanitized with quicklime to 50% dry basis and undergo a maturation period of 30 days, then were subjected to laboratory analysis. The parameters were analyzed with respect to stability, the trace elements of metals and resistant pathogens. The results were compared with the current legislation standards. GIS techniques and geographic information systems (GIS) in order to identify potentially suitable for areas receiving biosolids were also used. According to the results, the drying bed natural exposure showed efficiency in dewatering and sludge stabilization, reaching levels lower than 10% humidity, the ratio between volatile and less than 0.10 total solids; with respect to the concentrations of trace elements of metals analyzed, all samples showed lower levels of biosolids to the maximum values allowed by CONAMA Resolution 375/06, including sample clean-truck fossa, which showed the highest levels of the analyzed parameters; after cleaning the sludge, the material presented quality Class A biosolids in relation to the concentration of pathogenic organisms; Finally, the study of the physical environment facilitated the disposal of biosolids at least 75.30% (2664.23 km ²) of the municipal area, while 24.70% (873,93km²) have restrictions because it is not local recommended for the application of this type of material.

This diploma thesis is focused on sludge management of wastewater treatment plant. The research work contains an overview of the related legislation, outlines the problems of sludge treatment in the Czech Republic and also deals with technologies and technical solutions that are related to the processing and treatment of sewage sludge for various size categories of wastewater treatment plants. The second part is devoted to the technical and economic assessment of wastewater treatment plants in the category from 500 EO to 2 000 EO. The assessment is based on real data provided by WWTP operators and focuses on electricity consumption, investment costs and operating costs. Part of the diploma thesis is also determining the rentability of drainage equipment, and studying the convenience of using mobile or stationary drainage equipment.

The concept of sludge management at the level of sludge treating technology of sewage treatment plants, as well as at national, continental or world level, requires fundamental improvement in the interest of sustainable development. Sewage sludge production is continuously increasing. Sewage sludge contains a number of pollutants but also a significant renewable resource for material transformation and / or energy recovery. Sewage sludge is composed of an inorganic mineral part and organic components. Its organic part is a source of energy and nutrients, but also contains harmful pollutants for exapmple heavy metals. However, there are technologies that offer the possibility of neutralizing pollutants while using other sludge components in terms of recycling energy, nutrients and other attractive sludge components. The mentioned technologies include mainly thermal methods of sewage sludge treatment and one of them is pyrolysis. Thessis focuses on sewage sludge prepartation for pyrolysis process, which includes mixing with additives and peletization of prepared mixture for purposes of agricultural or energetical utilisation. Technology for material transformation and energy utilization of sewage sludge, in particular the mentioned pyrolysis or torrefaction, require an insignificant degree of detailed research in order to expand it in the field of sludge management. Indeed, it is not only research that will enable direct correct use of this technology in practice. The results of such research are the basis for the drafting of the relevant legislation, which will subsequently enable the deployment of pyrolysis technologies in practice.

Chemical coagulation is a widely used wastewater treatment method around the world to reduce impurities from the process water in various industries. However, the large amounts of coagulation chemicals that are required for the removal of dissolved particles create a chemical sludge which poses a great environmental problem. Purac AB, a Swedish wastewater treatment company attempts to solve this problem with a new technology called the ReAl process. The ReAl process can recycle the aluminium ions from the commonly used coagulant aluminium sulfate, which reduces the amount of chemical sludge and the amount of aluminium sulfate needed in the coagulation process. In this study, a comparative life cycle assessment was conducted with a cradle-to-grave approach and mostly in accordance with the ISO-14040 series with the only deviation of not including resource-based impact categories. The goal was to evaluate the environmental impact of two sludge treatment systems – a conventional system (system 1) and a system which includes the ReAl process (system 2). Furthermore, the environmental performance of two dewatering equipment’s, a decanter centrifuge and a filter press, were examined in system 1, while in system 2, the exclusion of sludge drying was investigated. The scope of the study did not include the infrastructure of the sludge treatment systems and the ReAl process since previous studies have shown that, the environmental impact from the infrastructure in the wastewater treatment industry is relatively small compared to other factors, such as the energy and coagulation chemical used in these systems. The characterization results showed that system 2 had the lowest environmental impact on all the evaluated impact categories. The results also revealed that system 1 would have a slightly lower environmental impact if the chemical sludge was dewatered with a decanter centrifuge instead of a filter press. Similarly, system 2 would have a slightly lower environmental impact if sludge drying was excluded from the system. However, the environmental performance gain from selecting the best dewatering and drying equipment is limited and considered within the margin of error. Thus, this thesis suggests selecting the sludge treatment equipment based on their economic and technical factors before their environmental performance. The largest environmental impact in system 1 derived from the use of the coagulation chemical aluminium sulfate, while in system 2, sulfuric acid used in the ReAl process contributed the most to its environmental impact. The sensitivity analysis showed that a “clean” electricity mix is essential for system 2 and the ReAl process overall impact on the environment compared to system 1.

O tratamento de esgotos é essencial à manutenção de suprimento de água nos centros urbanos em condições desejáveis à saúde pública. A carência de saneamento em nosso país mostra a necessidade de alternativas tecnológicas para o tratamento de esgotos. Na busca de novas opções, iniciou-se na CETESB em 1983, o estudo de sistemas compactos para tratamento direto de esgotos pela via anaeróbia. O reator anaeróbio de fluxo ascendente e manto de lodo (reator UASB) foi estudado em escala piloto e mostrou-se viável e eficiente, levando à necessidade de se efetuar o aumento de escala para o completo desenvolvimento da tecnologia. Um reator UASB de 120 m3 foi construído. Durante sete anos (de 1987 a 1993) funcionou sob observação, o que possibilitou o domínio da tecnologia. O sistema operou à temperatura ambiente em três períodos distintos. No primeiro período estudou-se as eficiências de remoção de matéria orgânica e a produção de gás e de lodo. Com tempo de retenção hidráulica médio de 6,5 horas, obteve-se efluente com 113 mg DQO/L, 48 mg DBO/L e 39 mg SST/L. As eficiências de remoção de DQO, DBO e SST foram respectivamente de 59, 65 e 76 por cento. A remoção de Coliformes totais e fecais ficou entre 70 e 90 por cento. Sua desinfecção através de métodos convencionais como cloração, ozonização ou radiação ultravioleta mostrou-se eficiente, a exemplo da maioria dos sistemas secundários de tratamento de efluentes. Obteve-se como fator de produção de lodo 0,2 kg ST/kg DQO da alimentação, sendo esta baixa produção de lodo uma das grandes vantagens do processo anaeróbio tendo em vista o custo e o trabalho que representam o tratamento e disposição do lodo no tratamento de esgotos. A produção de gás foi de 120 NL/kg de DQO alimentado. Efetuou-se também o acompanhamento microbiológico do lodo através de metodologia específica de acompanhamento de biomassa de biodigestores, o que possibilitou o aprimoramento dos conhecimentos da formação da biomassa no decorrer do processo. No segundo período de operação comprovou-se os resultados obtidos no primeiro período. No terceiro período de operação, apoiando-se nas técnicas de análise microbiológica da biomassa, estudou-se a partida a fim de diminuir o tempo para se atingir o regime estacionário. A utilização de inóculo não adaptado, como o lodo de esgoto de reator convencional, requer três a quatro meses para atingir o estado estacionário, com as eficiências relatadas. A partir da experiência adquirida são efetuadas recomendações e considerações para dimensionamento, partida, operação, manutenção e monitoramento para servir como guia aqueles que forem utilizar esta nova tecnologia. Após a partida o sistema apresenta reprodutibilidade, confiabilidade e estabilidade de operação. O controle do sistema, quando se trata de esgoto doméstico, é bastante simples, necessitando apenas remoção periódica de lodo, além da manutenção e limpeza. Há necessidade de remoção periódica de escuma. O dimensionamento do reator sofreu aperfeiçoamentos para melhorar a separação das três fases sólida, líquida e gasosa. Além dos critérios adotados anteriormente a partir do reator piloto de 106 L que possibilitou o estabelecimento de critérios como velocidade superficial no decantador de O,7 m3/m2/h, velocidade do líquido através da abertura inferior do decantador de 5 m3/m2/h e inclinação das paredes do decantador de 50°, observou-se que o transpasse entre a parede do decantador e do defletor de gases deve ter no mínimo 15 em para assegurar que o gás não desvie para dentro do decantador. O limite de velocidade no corpo do reator não deve ultrapassar 1 m3/m2h para garantir o acúmulo de lodo no reator. O lodo apresentou granulação com diâmetros de até 2 mm. Os processos de pós tratamento que vem sendo testados dão os polimentos necessários e adequados às diversas condições de reuso ou descarte do efluente. O sistema é hoje relativamente bastante utilizado, quando se leva em conta os parcos investimentos havidos no setor nos últimos anos. No Estado de São Paulo, a aplicação desta tecnologia foi efetuada através de um convênio entre a CETESB e o DAE-Sumaré, no Jardim Santa Maria, um loteamento de 1500 habitantes. Esse trabalho, mostrou a viabilidade de sua aplicação e comprovou os resultados obtidos, assim como várias experiências realizadas por outras instituições com processo anaeróbio também o demonstraram. No Estado do Paraná, o processo anaeróbio tem sido empregado sistematicamente para o tratamento de esgotos pela Companhia de Saneamento daquele Estado, a SANEPAR. A divulgação dessas experiências e de tantas outras existentes, deve proporcionar a confiança na tecnologia possibilitando sua expansão e a melhoria da qualidade de nossas águas. / Sewage treatment is essential to water supplying in urban nuclei with desirable conditions of public health. The lack of sanitation in our country shows the necessity of sewage treatment technologies compatible to our reality. Searching for new technologies, CETESB has started in 1983, the study of new compact anaerobic treatment systems for sewage. The UASB reactor was studied in pilot scale showing the need of scaling up for it\'s complete technological development. For this purpose a 120m3 UASB reactor was built. During seven years (from 1987 to 1993) the system worked with methodological observation, which made possible the mastering of the technology. The system operated at ambient temperature in three distinct periods. In the first one the performance of organic matter removal and the gas and sludge production were studied. The results showed effluent with 113 mg COD/L, 48 mg BOD/L and 39 mg SST/L with 6.5 hours of hydraulic retention time. The COD, BOD and SST removal performances were respectively 59, 65 and 76 per cent. The faecal and total Coliform removal showed values between 70 and 90 per cent. The effluent disinfection by conventional methods as chlorination, ozonation and ultra violet radiation has showed to be efficient, as the majority of effluent secondary treatment systems. The sludge production was 0.2 kg ST/kg COD in the feed. This low sludge production is one of the biggest advantages of the anaerobic process, in view of the costly and great disturbances that represent the sludge treatment and disposal in the sewage treatment. The gas production was 120 NL/kg COD of the feed. The biomass growth was followed by means of a microbilogical analysis specially developed for biodigesters sludge. In the second operation period the results were confirmed. In the third operation period, also followed by means of microbiological technical analysis, the shortening of the start up time was studied. It was found that starting up with unacclimatized inoculum, the stationary condition takes three to four months to be achieved, with the performances related. Based on the experience gathered, recommendations are made for system design, start up, operation, maintenance and monitoring. After the start up, the system shows reproducibility, reliability and stable operation. For essentially domestic sewage, the control system is very simple, necessitating only periodical sludge removal in addition to the maintenance activities. There is necessity of periodically scum removal. The design of the reactor was changed to improve the separation of solid, liquid and gaseous phases. Besides the design criteria described before, based on pilot scale experience, such as surface velocity in the settler area of O.7 m3/m2.h, liquid velocity in the lower aperture of the settling chamber 5 m3/m2.h with minimum HRT of four hours and slope of settling chamber walls of 50°, it was observed that it needs 15 cm in the crossing between the settler wall and the gas deflector to assure no gas deviation to the settler compartment. The maximum upflow velocity in the reactor body is 1 m3/m2.h to warrant retention of sludge in the reactor. Pellets in sludge presented up to 2 mm in diameter. Post-treatments may be necessary to give the effluent the appropriated conditions for its reuse or discharge. Today, the system is quite used in Brazil, taking in account the low investments in the sector. In the State of Sao Paulo, an example of this technology transfer is the agreement signed by CETESB and DAE-Sumaré, at \"Jardim Sta. Maria\", a small community of 1500 inhabitants. This work confirmed the results obtained and showed the feasibility of its application. Other experiences made by other institutions with anaerobic process confirmed them as well. In the State of Parana, the anaerobic process has been employed systematically for sewage treatment by the State Sanitation Company. The diffusion of this experiences and of many others existing might provide the confidence in the technology, enabling its expansion and the improvement of the quality of our waters.