José Eduardo Alamy Filho

Estudo da autodepuração do rio Jordão, localizado na bacia hidrográfica do rio Dourados

O artigo avaliou a capacidade de autodepuracao do rio Jordao que considera as contribuicoes reais do corrego Brejo Alegre em periodo de estiagem e 2 (dois) cenarios que consideram as cargas poluidoras estimadas de ETE – Estacao de Tratamento de Esgoto e a baixa capacidade de diluicao do rio para a vazao critica Q 7,10 , atraves do modelo QUAL-UFMG. A simulacao na estiagem apresentou satisfatoria calibracao atraves do ajuste dos coeficientes K 1 e K d , evidenciando a prevalencia da desoxigenacao por demanda carbonacea sobre a nitrificacao e a importância da reaeracao natural no processo de autodepuracao. Apenas o parâmetro DBO nao respeitou os limites preconizados pela Resolucao CONAMA 357:2005, onde 78,9% de sua extensao ficaram fora da regulamentacao devido ao recebimento de cargas poluidoras do corrego Brejo Alegre. Quanto as simulacoes dos cenarios, uma populacao de 58.860 habitantes para o Cenario 1 e 114.000 habitantes para o Cenario 2 garantiriam a capacidade de autodepuracao, considerando-se as imprecisoes da metodologia de analise da DBO e que adotou-se uma vazao critica 2,6 vezes inferior a menor vazao medida no periodo de estiagem.

VELOCITY AND CONCENTRATION OF BUBBLES IN OZONIZATION COLUMNS WITH CROSS SECTIONS OF DIFFERENT SIZES

The size of the cross section of an ozonization column influences its hydrodynamic characteristics, which, on its turn, has effects on phenomena that depend on the relative movement between gas bubbles and liquid. To observe the influence of the cross sectional area on gas concentration and bubbles velocity, two columns were used. The first column had a square cross section with side of 0.19 m and the second had a circular cross section with diameter of 0.10 m. The ascendant velocities of the bubbles and their concentration were measured in both columns and compared. The transversal spread of the plumes of bubbles was also quantified. The results show that the increase of the cross section of the column, in the proportion studied here, does not result in a similar increase of the cross section of the ascending plume of bubbles. Furthermore, the results of average velocities and concentrations obtained for the smallest cross section resulted independent of the liquid level in the column, while the results for the largest cross section showed to be dependent of this level. The ratio between the cross sectional areas of the larger and the smaller plumes of bubbles decreases for higher distances to the bottom of the columns.

DIAGNÓSTICO DA QUALIDADE DA ÁGUA DO AQUÍFERO BAURU NA ÁREA URBANA DE ARAGUARI, MG

This work was mainly focused on assessing the water quality of the aquifer Bauru in the city of Araguari, MG and verification of any changes related to the loss of water quality. The survey was based upon assessment of quality parameters of water samples extracted from wells. The wells were carefully chosen due their functionality within water supply system These analysis were combined with simulations of particle trajectories. The analyzed parameters can be related with pollution from sewage, with the diffuse input of fertilizers and with the presence of suspended solids. In this context, were analyzed the parameters nitrate, nitrite, pH, total phosphorus, COD, BOD, color, turbidity, coliform organisms and, finally, the series of solids. Considering the results for each individual water quality parameter, a correlation analysis was carried out. Computational simulations were used to locate the likely origin of substances found in wells. The results of water quality analyzes and simulations of particle trajectories indicate that sewage leaks, especially when occurring in zones whose natural vulnerability indices are higher, may be the cause of the presence of substances such as nitrate and volatile solids in some wells. Keywords: groundwater, water quality, Bauru aquifer.

EFICIÊNCIA HIDROLÓGICA DE TELHADOS VERDES PARA A ESCALA DE LOTEAMENTOS RESIDENCIAIS

O presente trabalho teve o objetivo de estimar o comportamento de um conjunto de telhados verdes em relacao a sua capacidade de inibicao do escoamento superficial, utilizando a escala espacial de loteamento. A eficiencia hidrologica dos telhados verdes foi avaliada em funcao da reducao relativa do volume de escoamento superficial, comparando a situacao de implantacao da cobertura permeavel, em todas as edificacoes de um loteamento, com a situacao de telhado convencional impermeavel. As estimativas teoricas utilizaram um modelo hidrologico, com imposicao de diversos cenarios de precipitacao. O efeito das chuvas foi introduzido pela equacao de intensidade, duracao e frequencia local e por distribuicoes temporais sinteticas. Os tipos e usos do solo foram considerados a partir do parâmetro curva-numero. A metodologia proposta foi aplicada para um condominio residencial situado na cidade de Uberlândia, Minas Gerais. Os resultados das simulacoes hidrologicas indicaram que a implantacao de telhados verdes aponta para reducoes expressivas do volume de escoamento superficial. Neste contexto, estimaram-se eficiencias entre 2,02% e 55,67%. Para condicoes de solo inicialmente seco, que sao comuns apos estiagens, foi prevista uma eficiencia hidrologica media de 40,35%. A despeito disto, este indice reduz-se para 10,44% em situacoes de saturacao iminente, decorrentes de chuvas anteriores sucessivas. A despeito da sua dependencia da umidade antecedente do solo, este potencial de reducao do escoamento superficial e consideravel. Assim, a implantacao de telhados verdes contribui para atenuar as vazoes de pico geradas na saida do loteamento, aliviando o sistema publico de drenagem e, num contexto mais amplo, reduzindo os riscos de enchentes ribeirinhas nos fundos de vale. Palavras-chave: drenagem urbana, telhados verdes, escoamento superficial.

AVALIAÇÃO DE SISTEMA DE LEITO DE DRENAGEM NO DESAGUAMENTO DO LODO DE ESTAÇÃO DE TRATAMENTO DE ÁGUA COM ÊNFASE NA INFLUÊNCIA DOS AGENTES EXTERNOS NA FASE DE SECAGEM

Este trabalho teve como objetivo a avaliacao do desempenho do sistema de Leito de Drenagem em escala reduzida no desaguamento de lodo de uma Estacao de Tratamento de Agua. Foram avaliadas as fases de drenagem e secagem do lodo, sendo que na fase de secagem os ensaios foram conduzidos em duplicata para investigacao da influencia de fatores climaticos no tempo de secagem. Para tanto foram conduzidos experimentos com tres Leitos de Drenagem, cada um com uma manta geotextil diferente, avaliados sob a aplicacao de tres distintas taxas de aplicacao de solidos. Uma vez escolhida a melhor taxa de aplicacao de solidos, foram conduzidos ensaios nos quais foi avaliada a influencia parcial dos agentes externos apenas na fase de secagem, removendo-se a protecao lateral de um dos leitos. Foram avaliados, portanto, tres mantas geotexteis em ensaios em duplicata considerando a influencia parcial ou nao dos agentes climaticos. Assim, para cada manta estudada foram montados dois leitos de drenagem, um com a protecao lateral e outro sem a protecao lateral, totalizando seis leitos de drenagem. As fases de drenagem e de secagem do lodo foram avaliadas com taxas de aplicacao de solidos de 1,75 kg∙m-2, 3,5 kg∙m-2 e 7,0 kg∙m-2. Na fase de drenagem foi avaliado o parâmetro turbidez e na fase de secagem foi observada a influencia das variaveis climaticas no desaguamento do lodo por meio da obtencao do teor de solidos. Ressalta-se que os Leitos de Drenagem foram protegidos da incidencia direta da chuva, ou seja, a influencia foi indireta. O efluente do drenado apresentou, logo no inicio de operacao do sistema, turbidez abaixo de 10 NTU e, ao final, proximo de 1 UNT e o lodo apresentou teor de solidos 50% maior para o LD sem protecao lateral (envoltoria). Palavras chaves: Estacao de Tratamento de Agua (ETA), Geotexteis, Lodo, Leitos de drenagem. ABSTRACT The aim of this work was to evaluate the performance of the System Draining Beds sludge dewatering in a Water Treatment Plant. Phase’s drainage and drying of the sludge were evaluated, and the drying phase assays were conducted in duplicate for investigation of the influence of climatic factors on the drying time. Both experiments with three Draining Beds, each with a different geotextile, evaluated under the application of three different application rates of solids, were conducted. Once chosen the best application rate of solids, trials were conducted in which the partial influence of external agents was assessed only at the stage of drying, removing the lateral protection of the beds. Therefore, there were evaluated three geotextile blankets trials in duplicate considering partial or none influence of climatic agents. Then, for each bed studied, two blanket drain were assembled, one with side protection and other without side protection, totaling six beds of drainage. The steps of draining and drying of the sludge were evaluated at application rates of 1.75 kg∙m-2, 3.5 kg∙m-2 and 7.0 kg∙m-2 of solids. In a drain phase, the parameter turbidity was evaluated and in the drying step the influence of climate variables were observed in the dewatering of sludge to the obtained solids. It is noteworthy that the Draining Beds were protected from direct impact of rain, i.e., the influence was indirect. The effluent drained presented, earlier in the system operation, turbidity below 10 NTU and, at the end, turbidity near 1 NTU and the sludge solids showed 50% greater for the LD without lateral protection. Keywords: Water Treatment Plants (WTP), Geotextiles, Sludge, System Draining beds.

Moving beds represented by immersed boundaries: numerical experiments using large eddy simulation

The Immerse Boundary Method (IBM) was used to evaluate the sediment transport over deformable beds. Large Eddy Simulation (LES) procedures were used for the mathematical treatment of turbulence, and the advection-diffusion equation was used to calculate sediment concentration. The Finite Differences Method with staggered grid was applied for the numerical solution of the governing equations (filtered Navier-Stokes, Continuity and advection-diffusion equations). Spatial derivatives were discretized using second order centered differences. A second order explicit Adams-Bashforth scheme was used for the time evolution in the advection-diffusion equation, while a fourth order Adams-Bashforth scheme was used for the filtered Navier-Stokes equations. The numerical simulation reproduced flow structures like large eddies after the dune crests and counter-rotative vortices, which are important in sediment transport. Resuspension fluxes and sedimentation (dependent on particle concentration) were calculated using equations proposed in this study. The deformations of the bed caused by erosion and deposition may be well followed through the present procedures, showing that this methodology is adequate to evaluate bed modifications and sediment transport in alluvial flows.