Knowledge of water distribution in sludges is important in developing a better understanding of the mechanisms by which various fractions of water are bound to the sludge matrix as well as the extent to which sludges may be dewatered in an economic manner. Various models have been proposed in the literature to describe the types or fractions of water present in sludges, both before and after dewatering. Likewise, there exist a variety of measurement techniques to quantify the fractions of water believed to be present in sludges. The major objective of the research reported herein was an attempt to develop a more rational basis for defining the various fractions of water present in sludges, as well as to apply and develop feasible analytical techniques to characterize moisture distribution in sludges and determine if there was any correlation between these techniques. Secondary objectives included investigation of polymer addition, mechanical dewatering, and the effect of freeze-thaw cycles to different water fractions in sludge samples, and measuring or estimating various densities (bulk, floc, dry) and specific surface areas of sludge particles in an attempt to predict the dewatering performance of various sludge samples. The matrix of sludges included various water treatment plant/inorganic chemical sludges and biosolids. The sludge moisture characterization techniques used or developed in this study were the thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dilatometric methods. The TGA method developed used the drying curve rate technique whereby changes in the drying (water removal) rates would provide information on moisture distribution in sludges. The DSC and dilatometric methods used the property of the free water fraction to freeze by -20° C, as compared to the bound water fraction that is thought not to freeze until well below -20°C. It was found that there were uncertainties in the determination of different sub-fractions of sludge water. In an effort to better rationalize these various subfractions, it has been proposed in this study that water in sludges be considered to be in two major fractions: bound and unbound. For the TGA, the demarcation point between these two fractions was indicated by the onset of the first critical/inflection point on the drying rate curve. The DSC and dilatometric methods determined the amount of bound water by first measuring the amount of unbound water that froze by -20°C, and subtracting this value from the total water present in the dry solids analysis. While the DSC measured the calorimetric (enthalpic) changes, the dilatometer measured the expansion of the unbound water. The three DSC instruments evaluated in this study were not able to measure the rapid exothermic change of the freezing of unbound water, but was able to measure the amount of unbound water that melted. Freezing point depression (supercooling) phenomena was also observed for various samples using this technique. Due to these effects, the sludge moisture characterization method developed for the DSC measured the amount of unbound water from the endothermic changes upon melting. The three different analytical techniques used to determine moisture in sludges were found to provide different quantities of the bound water fraction. Other sludge characteristics evaluated included the bulk, floc, and dry density values, as well as the specific surface area of dry sludge particles. Correlations were attempted to determine if there were any meaningful relationships in the results obtained. / Ph. D.

A microcomputer simulation model was developed to compare sludge disposal alternatives for an urban region. The model calculates both capital and operation costs for sludge treatment and disposal operations. For a study of an urban region with an equilibrium wastewater generation rate of 44.74 million m³/yr, the optimum sludge disposal alternative was dedicated land disposal for a baseline analysis of wastewater sludge treated by gravity thickening and anaerobic digestion. The capital cost at system equilibrium is $6.09 million and the total cumulative operation and maintenance cost over 100 years is $103.2 million. The operation and maintenance cost is 94% of the total capital and cumulative operation and maintenance cost. A description of the investigation and the criteria used for selection of this sludge disposal alternative ls included / Master of Science

Neste trabalho avaliou-se o desempenho de um reator anaeróbio de fluxo ascendente e manta de lodo (UASB) no tratamento combinado de esgoto sanitário com o lançamento de lodo proveniente de tanques sépticos. O estudo foi desenvolvido em escala plena na Estação de Tratamento de Esgoto (ETE) do Campus I da Universidade de São Paulo (USP) em São Carlos-SP. Foram utilizados dois reatores UASB com 18,8 m³ cada, um reator (UASB I) com função de controle e o outro reator (UASB II) no qual foi descarregado o lodo séptico. A pesquisa foi dividida em duas etapas: a primeira compreendeu o início de operação e o monitoramento dos reatores e, da segunda fez parte os ensaios de lançamento de lodo séptico no sistema. A partida foi efetuada sem utilização de inóculo e os reatores foram operados com tempo de detenção hidráulica médio (TDH) de 8 h, vazão afluente média de 2,35 m³/h e velocidade ascensional de 0,6 m/h. Em seis meses de operação os reatores apresentaram eficiências médias de remoção de DQO nos reatores UASB I e UASB II iguais a 49% e 65%. Quanto à remoção de sólidos os reatores UASB I e UASB II atingiram remoção de 36% e 37% para ST e de 67% e 63% para SST, respectivamente. Após esse período, deu-se início ao estudo que avaliou o impacto do lançamento de lodo séptico no UASB II. Foram realizados três ensaios com diferentes volumes de lodo (1; 3 e 5 m³) descarregados na forma de pulso com vazão média de 5,24 m³/h. Os lodos sépticos utilizados na pesquisa foram coletados por caminhões limpa-fossa e descarregados em um reservatório (15 m³) na ETE para posterior lançamento no reator UASB II. Foram feitas as caracterizações das amostras dos lodos sépticos (coletadas no ato da descarga em cada ensaio), com as quais pôde-se constatar a heterogeneidade da composição desse tipo de resíduo e sua viabilidade de pós-tratamento anaeróbio. Nos ensaios foram realizados monitoramentos temporais logo após a descarga de lodo para acompanhamento da resposta ao pulso de carga imposto. No geral, o reator UASB apresentou capacidade de degradar aproximadamente 2/3 da carga orgânica lançada com o lodo séptico. Os resultados são um indicativo de que a disposição de lodo sépticos em reatores UASB, quando bem programada, é uma solução viável e de grande importância para o tratamento dos resíduos provenientes de tanques/fossas sépticas. / The performance of upflow anaerobic sludge blanket (UASB) in the sanitary wastewater combined treatment with sludge disposal of septic tanks was evaluated in this work. The study was carried out (full scale) in the Wastewater Treatment Plant (WTP) located in campus I of the University of Sao Paulo (USP), city of Sao Carlos, State of Sao Paulo, Brazil. Two UASB reactors were used; volume of each reactor ~ 18,8 m³. UASB I was the control reactor, and UASB II was the reactor in which the septic sludge was disposed. The research was divided in two steps: the first one, which has taken into account the beginning of reactors operation and, the second one, in which occurred the disposal of septic sludge in the reactors. The start-up was carried out without utilization of inoculums. Reactors were operated with an average hydraulic retention time of 8 hours, average influent flow rate of 2.35 m³/h, and upflow velocity of 0.6 m/h. In six months, reactors presented average removal efficiencies of COD in UASB I and UASB II of 48% and 65%, respectively. Concerning to the solid removal, UASB I and UASB II have achieved removal of 36% and 37% for TS, and 67% and 63% for TSS, respectively. After this period of time, the evaluation of disposal impact of septic sludge was started in UASB II. Three essays with different sludge volume (1, 3, and 5 m³) were carried out; sludge volume was disposed in a pulse way with average flow rate of 5.24 m³/h. Septic sludge utilized in the research was collected by clean septic tank trucks, and disposed in a reservoir (volume of 15 m³) in WTP, in order to allow further disposal in the UASB II. By the hand of characterization of septic sludge samples (collected when disposal was carried out), it was possible to verify the heterogeneity about composition of this kind of waste and its availability in terms of anaerobic post-treatment. Temporal monitoring after the sludge disposal was carried out in order to allow the accompaniment of results provided by the pulse. In general, UASB reactor presented capacity in terms of degradation of approximately 2/3 of the organic load disposed with septic sludge. The results are a good indicative that the disposal of septic sludge in UASB reactors is a viable solution, and it is very important for the treatment of wastes from septic tanks.

Neste trabalho avaliou-se o desempenho de um reator anaeróbio de fluxo ascendente e manta de lodo (UASB) no tratamento combinado de esgoto sanitário com o lançamento de lodo proveniente de tanques sépticos. O estudo foi desenvolvido em escala plena na Estação de Tratamento de Esgoto (ETE) do Campus I da Universidade de São Paulo (USP) em São Carlos-SP. Foram utilizados dois reatores UASB com 18,8 m³ cada, um reator (UASB I) com função de controle e o outro reator (UASB II) no qual foi descarregado o lodo séptico. A pesquisa foi dividida em duas etapas: a primeira compreendeu o início de operação e o monitoramento dos reatores e, da segunda fez parte os ensaios de lançamento de lodo séptico no sistema. A partida foi efetuada sem utilização de inóculo e os reatores foram operados com tempo de detenção hidráulica médio (TDH) de 8 h, vazão afluente média de 2,35 m³/h e velocidade ascensional de 0,6 m/h. Em seis meses de operação os reatores apresentaram eficiências médias de remoção de DQO nos reatores UASB I e UASB II iguais a 49% e 65%. Quanto à remoção de sólidos os reatores UASB I e UASB II atingiram remoção de 36% e 37% para ST e de 67% e 63% para SST, respectivamente. Após esse período, deu-se início ao estudo que avaliou o impacto do lançamento de lodo séptico no UASB II. Foram realizados três ensaios com diferentes volumes de lodo (1; 3 e 5 m³) descarregados na forma de pulso com vazão média de 5,24 m³/h. Os lodos sépticos utilizados na pesquisa foram coletados por caminhões limpa-fossa e descarregados em um reservatório (15 m³) na ETE para posterior lançamento no reator UASB II. Foram feitas as caracterizações das amostras dos lodos sépticos (coletadas no ato da descarga em cada ensaio), com as quais pôde-se constatar a heterogeneidade da composição desse tipo de resíduo e sua viabilidade de pós-tratamento anaeróbio. Nos ensaios foram realizados monitoramentos temporais logo após a descarga de lodo para acompanhamento da resposta ao pulso de carga imposto. No geral, o reator UASB apresentou capacidade de degradar aproximadamente 2/3 da carga orgânica lançada com o lodo séptico. Os resultados são um indicativo de que a disposição de lodo sépticos em reatores UASB, quando bem programada, é uma solução viável e de grande importância para o tratamento dos resíduos provenientes de tanques/fossas sépticas. / The performance of upflow anaerobic sludge blanket (UASB) in the sanitary wastewater combined treatment with sludge disposal of septic tanks was evaluated in this work. The study was carried out (full scale) in the Wastewater Treatment Plant (WTP) located in campus I of the University of Sao Paulo (USP), city of Sao Carlos, State of Sao Paulo, Brazil. Two UASB reactors were used; volume of each reactor ~ 18,8 m³. UASB I was the control reactor, and UASB II was the reactor in which the septic sludge was disposed. The research was divided in two steps: the first one, which has taken into account the beginning of reactors operation and, the second one, in which occurred the disposal of septic sludge in the reactors. The start-up was carried out without utilization of inoculums. Reactors were operated with an average hydraulic retention time of 8 hours, average influent flow rate of 2.35 m³/h, and upflow velocity of 0.6 m/h. In six months, reactors presented average removal efficiencies of COD in UASB I and UASB II of 48% and 65%, respectively. Concerning to the solid removal, UASB I and UASB II have achieved removal of 36% and 37% for TS, and 67% and 63% for TSS, respectively. After this period of time, the evaluation of disposal impact of septic sludge was started in UASB II. Three essays with different sludge volume (1, 3, and 5 m³) were carried out; sludge volume was disposed in a pulse way with average flow rate of 5.24 m³/h. Septic sludge utilized in the research was collected by clean septic tank trucks, and disposed in a reservoir (volume of 15 m³) in WTP, in order to allow further disposal in the UASB II. By the hand of characterization of septic sludge samples (collected when disposal was carried out), it was possible to verify the heterogeneity about composition of this kind of waste and its availability in terms of anaerobic post-treatment. Temporal monitoring after the sludge disposal was carried out in order to allow the accompaniment of results provided by the pulse. In general, UASB reactor presented capacity in terms of degradation of approximately 2/3 of the organic load disposed with septic sludge. The results are a good indicative that the disposal of septic sludge in UASB reactors is a viable solution, and it is very important for the treatment of wastes from septic tanks.