Investigación sobre la eliminación de olores en depuradoras

La emisión de olores en las depuradoras de aguas residuales representa un impacto significativo. Una mayor concientización de la población sobre sus derechos y el aumento del números de depuradoras en explotación, asociadas a las presiones urbanas sobre áreas desocupadas que fuerzan la construcción de residencias y/o complejos de ocio cada vez más próximos de las depuradoras, obligan a las empresas responsables de las depuradoras a considerar este problema, buscando soluciones de forma constante para evitar conflictos con las comunidades. La utilización de procesos electroquímicos para el tratamiento de aguas residuales está adquiriendo cada día más importancia por su versatilidad, reducido tamaño y capacidad de automatización. En este sentido, resultan de especial interés la electrocoagulación, como procedimiento de tratamiento de compuestos olorosos presentes en aguas residuales. Durante la presente investigación se ha estudiado la eliminación de los siguientes compuestos olorosos mediante el proceso de electrocoagulación: sulfuro de carbono, amoniaco, acido acético, tolueno y diclorometano. Se ha investigado, al efecto, del diseño del reactor (configuración 1 fuente, configuración de 2 fuentes seguidas y configuración de 2 fuentes separadas), naturaleza de los electrodos (grafito y aluminio), y corriente eléctrica aplicada (0,5 A, 2 A, 4 A, 6 A, 8 A y 9,5 A). La investigación experimental se ha llevado a cabo en una planta piloto de la Cátedra de Ingeniaría Sanitaria, instalada en la EDAR de Viveros de la Villa, empleando como influente el agua residual procedente de la decantación secundaria de depuradora. Para simular el tratamiento fue necesario adicionar los productos artificialmente en el tanque de pre-tratamiento de la planta piloto. En referencia al amoniaco, se realizaran con la adición artificial del amoniaco para simular el tratamiento en la cabecera de la planta, y sin la adición artificial del amoniaco para simular el tratamiento como un afino para depuradas. Mediante el tratamiento con ánodo de aluminio y cátodo de aluminio se observaron rendimientos satisfactorios para el sulfuro de carbono y se determinó un rendimiento óptimo mediante electrodos de aluminio separados entre sí 2,5 cm., utilizando la configuración de 1 fuente, y aplicando intensidades muy bajas (0,5 amperios). No se observó acción significativa sobre el contenido de acido acético, tolueno, diclorometano y amoniaco, sin embargo se desarrolla una aceleración de la oxidación en el agua muestreada al disminuir las concentraciones de nitrito y aumentar las concentraciones de nitrato. La electrooxidación, mediante ánodo de grafito, se presentó como una técnica eficiente para un afino de depuradoras en relación a la eliminación del amoniaco, presentando rendimientos apreciables para el tratamiento de amoniaco en la cabecera de depuradoras. Se alcanzaron rendimientos medios de 34% en la reducción del amoniaco, utilizando la configuración 2 fuentes seguidas con electrodos separados entre sí 2,5 cm., aplicando 4 amperios de corriente eléctrica y consumiendo 15 w/h. Se concluye también que el rendimiento del proceso se presenta inversamente proporcional a las concentraciones de amoniaco en la entrada del proceso, y que la mayor parte del amonio eliminado por electrooxidación pasa a nitrógeno gas. Desde el punto de vista económico la electrooxidación mediante ánodo de grafito es eficiente por presentar los mayores rendimientos con un aporte de energía bajo y bajos tiempos de retención. A pesar del comportamiento variable del sulfuro de carbono se observaran rendimientos satisfactorios para el sulfuro de carbono y se determinó un rendimiento óptimo mediante electrodos de aluminio separados entre sí 2,5 cm., utilizando la configuración de 1 fuente, y aplicando intensidades muy bajas (0,5 amperios). En referencia al tolueno se apreció un ligero rendimiento, mientras que no se observó acción significativa sobre el diclorometano y acido acético. El objetivo fundamental buscado, y alcanzado en esta investigación, es facilitar el escalonado de procesos de electrocoagulación necesarios para la eliminación de compuestos olorosos presentes en aguas residuales. Se concluye entonces que esta técnica es una arma positiva que permite una optimización de la calidad del agua eliminando compuestos olorosos. ABSTRACT The present work of investigation is about eletrocoagulation as a process of treatment of odours in wastewater, in view of the effects produced in society through emission of odours in wastewater treatment plants. In this context, the factors that stand out as a conscientization of population, increase the number of wastewater treatment plants associated to urban pressures and the construction of houses and recreation areas even closer of wastewater treatment plants. For these reasons, the companies responsible for operating the wastewater treatment plants are forced to consider this problem, constantly seeking solutions to avoid conflicts with communities. The use of electrochemical processes in wastewater treatment has been gaining increasing importance, due to its versatility, compactness and automation capability. In this sense, it is of great interest to a study of the electrocoagulation procedure as treatment of odorous compounds present in wastewater. This research concentrates on the elimination of carbon sulfide, ammonia, acetic acid, toluene and dichloromethane, through the process of electrocoagulation. It takes into account the effect of reactor configuration (configuration 1 source, 2 sources followed configuration and configuration 2 separate sources), the nature of the electrodes (graphite and aluminum), and applied electric current (0.5 A, 2 A , 4 A, 6 A, 8 A y 9.5 A). The experimental part of this thesis has been carried out in a pilot plant of the Department of Sanitary Engineering, located at the wastewater treatment plants of Viveros de la Villa (Madrid / Spain), using as influent water coming from the secondary sedimentation tank. In the simulation of the treatment was necessary to artificially add the parameters in the tank pre-treatment of this pilot plant. Experiments were carried out with artificial addition of ammonia to simulate the treatment in the beginning of the station and others without the addition of it to simulate the treatment as an improvement. Using aluminum anode and cathode aluminum, satisfactory yields were obtained for the carbon sulfide was identified optimum performance, electrodes separated by 2.5 cm, by configuration 1 source, and using very low intensities (0, 5 amp). Significant action on the concentration of acetic acid, toluene, dichloromethane and ammonia was not seen. However, It was produced an acceleration of the oxidation of water to lower concentrations of nitrite and increase nitrate concentrations. The process using graphite anode was presented as an efficient technique for improving wastewater treatment plants in relation to the elimination of ammonia, as well as was possible to observe appreciable yields for the treatment of ammonia in the station entrance, once found to average yields 34%, using the configuration with 2 sources followed electrodes separated 2.5 cm. by applying 4 amps and consuming 15 w / h. It was concluded also that the process yield is inversely proportional to the concentration of ammonia in the entry process and that most of the ammonia eliminated is eletrooxidado and reduced to nitrogen gas. From the economic point of view, the electrooxidation by graphite anode is effective for presenting the highest yields, requiring a low power consumption and small retention times. The fundamental objective planned and achieved in this research is to facilitate the best configuration of the electrocoagulation process to remove odorous compounds found in sewage. It can be concluded that this technique is a procedure that allows a good optimization of water quality by eliminating odorous compounds

Eliminación de compuestos volátiles olorosos por electrocoagulación

La emisión de olores en las depuradoras de aguas residuales representa un impacto significativo. En este sentido, resulta de especial interés la electrocoagulación, como procedimiento de tratamiento de compuestos olorosos presentes en aguas residuales. Durante la presente investigación se ha estudiado la eliminación de los siguientes compuestos volátiles olorosos mediante el proceso de electrocoagulación: sulfuro de carbono, tolueno y diclorometano. Se ha investigado el efecto del diseño del reactor (configuración de una fuente, configuración de 2 fuentes seguidas y configuración de 2 fuentes separadas), naturaleza de los electrodos (aluminio), y corriente eléctrica aplicada (0,5A, 2A, 4A, 6A, 8A y 9,5A). Se observaron rendimientos satisfactorios para el sulfuro de carbono y se determinó un rendimiento óptimo mediante electrodos de aluminio separados entre sí 2,5cm, utilizando la configuración de 1 fuente, y aplicando intensidades muy bajas (0,5A). En referencia al tolueno se apreció un ligero rendimiento, mientras que no se observó acción significativa sobre el diclorometano. La configuración de 1 fuente, además de haber presentado los mejores rendimientos para el sulfuro de carbono y el tolueno, requiere un suministro de energía inferior y menores tiempos de retención

PARTICIPACIÓN CIUDADANA EN EL PLANEAMIENTO DE LAS ACCIONES DE LA EMATER-RN

Os serviços públicos de assistência técnica e extensão rural no país são desenvolvidos em espaço onde coexistem grupos sociais muito distintos, desde empresários do agrobusiness até grupos tradicionais de agricultores familiares. Tendo como tema a participação dos agricultores familiares na elaboração das ações de assistência técnica e extensão rural, o presente trabalho objetivou analisar o processo decisório participativo do planejamento 2005 da EMATER-RN, utilizando como referência teórica principal a escada de participação cidadã de Arnstein (1969).  Foi realizada uma pesquisa de campo, documental e bibliográfica, de tipo exploratório, com abordagem qualitativa, e os dados, coletados de diferentes fontes – entrevistas, observações não-participantes e documentos – foram submetidos à análise de conteúdo do tipo categorial (BARDIN, 1977). Os resultados evidenciaram que o nível de participação do agricultor no planejamento da instituição se encontra em uma situação intermediária entre uma participação simbólica e uma participação real. Esta busca contínua de aperfeiçoamento dos canais participativos é relevante, no sentido de que mais que a institucionalização, acredita-se que o aperfeiçoamento e a continuidade dos processos de gestão participativa dependem da relação, sempre tensionada e crescentemente qualificada, entre a sociedade organizada e o Estado.The public services of technical assistance and rural extension in the country have been developed in a space where very distinct social groups, which go from agribusiness to traditional agricultural families, coexist. Having as theme the participation of agricultural families in the elaboration of actions of technical assistance and rural extension, this paper aims to analyze the participating decisory process of EMATER’S-RN 2005 planning, using as main theoretical reference Arnstein’s (1969) ladder of citizen participation. A field research, documental and bibliographical, of an exploratory kind with a qualitative approach was done, and the data, collected from different sources – interviews, non-participant observations and documents - were submitted to a content analysis of categorical kind (BARDIN, 1977). Results evidenced that the level of participation by the farmer in the institution’s planning is in an intermediary situation between symbolic and real participation. This continuous search of improving the participative channels is relevant since, besides institutionalization, it is believed that the improvement and continuity of the process of participative management depend on the relation, always tensioned and qualified, between the organized society and the State.Los servicios públicos de asistencia técnica y extensión rural en el país son desarrollados en espacio donde coexisten grupos sociales muy distintos, de empresarios del agrobusiness hasta grupos tradicionales de agricultores familiares. Teniendo como tema la participación de los agricultores familiares en la elaboración de acciones de asistencia y extensión rural, el presente trabajo pretendió analizar el proceso decisorio participativo del planeamiento 2005 de la EMATER- RN, utilizando como referencia teórica principal la escalera de la participación ciudadana de Arnstein (1969). Fue realizada una investigación de campo, documental y  bibliográfica, de tipo exploratorio, con abordaje cualitativo y los datos recogidos en diferentes fuentes – entrevistas, observaciones no-participantes y documentos – fueron sometidos al análisis de contenido del tipo categorial (BARDIN, 1977). Los resultados evidenciaron que el nivel de participación del agricultor en el planeamiento de la institución se encuentra en una situación intermediaria entre una participación simbólica y una participación real. Esta continua búsqueda de perfeccionamiento de los canales participativos es relevante, en el sentido de que más que la institucionalización, se cree que el perfeccionamiento y la continuidad de los procesos de gestión participativa dependen de la relación, siempre tensionada y crecientemente cualificada, entre la sociedad organizada y el Estado

CORE and the Haldane Conjecture

The Contractor Renormalization group formalism (CORE) is a real-space renormalization group method which is the Hamiltonian analogue of the Wilson exact renormalization group equations. In an earlier paper\cite{QGAF} I showed that the Contractor Renormalization group (CORE) method could be used to map a theory of free quarks, and quarks interacting with gluons, into a generalized frustrated Heisenberg antiferromagnet (HAF) and proposed using CORE methods to study these theories. Since generalizations of HAF's exhibit all sorts of subtle behavior which, from a continuum point of view, are related to topological properties of the theory, it is important to know that CORE can be used to extract this physics. In this paper I show that despite the folklore which asserts that all real-space renormalization group schemes are necessarily inaccurate, simple Contractor Renormalization group (CORE) computations can give highly accurate results even if one only keeps a small number of states per block and a few terms in the cluster expansion. In addition I argue that even very simple CORE computations give a much better qualitative understanding of the physics than naive renormalization group methods. In particular I show that the simplest CORE computation yields a first principles understanding of how the famous Haldane conjecture works for the case of the spin-1/2 and spin-1 HAF.Comment: 36 pages, 4 figures, 5 tables, latex; extensive additions to conten

Electrochemical mediated oxidation of phenol using Ti/IrO2 and Ti/Pt-SnO2-Sb2O5 electrodes

The indirect electrochemical oxidation of phenol was studied at Ti/IrO2 and Ti/Pt-SnO2-Sb2O5 electrodes by bulk electrolysis experiments under galvanostatic control. The obtained results clearly shown that the electrode material was an impor­tant para­me­ter for the optimization of such processes determining their mecha­nism and oxidation products. Different current efficiencies were obtained at Ti/IrO2 and Ti/Pt-SnO2-Sb2O5, depending on the applied current density in the range from 10, 20 and 30 mA cm−2. The effect of the amount of dissolved NaCl was studied also. It was observed that the electrochemical processes (direct/indirect) favor specific oxidation pathways depending on electrocatalytic material. Phenol degradation generates several intermediates eventually leading to complete mineralization, as indicated by the results obtained with the High-performance liquid chromatography (HPLC) technique

Porte da gramínea e inclusão da cunhã modificam o valor nutritivo da silagem de capim-elefante

The objective of this work was to evaluate the nutritional value of silages from tall-sized and dwarf elephant grass (Pennisetum purpureum) genotypes, intercropped or not with butterfly pea (Clitoria ternatea). The experiment was performed in randomized complete blocks, in a 4x2 factorial arrangement (four genotypes × two cropping systems). The genotypes intercropped or not with butterfly pea were: IRI-381 and Elephant B, tall sized; and Taiwan A-146 2.37 and Mott, dwarf. Forage was harvested 60 days after regrowth. In the silage from Mott grass intercropped with butterfly pea, lower contents of lignin (78.1 g kg-1), neutral detergent fiber (636.0 g kg-1), and neutral detergent insoluble protein (13.15 g kg-1), besides a greater dry matter recovery (873.3 g kg-1), were observed. The silage from Taiwan A-146 2.37 intercropped with the legume showed a greater crude protein content (136.1 g kg-1). In both silages, the ammonia nitrogen contents were quite reduced (26.4 g kg-1). However, greater residual water-soluble carbohydrate contents were observed in the silages from the intercrop (1.85 mg g-1) and from the Mott grass monocrop (1.51 mg g-1). Moreover, there was a lower in vitro dry matter digestibility (676.7 g kg-1) for the silage from the intercrop. Dwarf genotypes increase the nutritional value of elephant grass silage, compared with the tall-sized ones. Intercropping with butterfly pea improves silage fermentation characteristics, despite reducing its digestibility. Therefore, the ensilage of dwarf Mott elephant grass intercropped with butterfly pea shows more promising results.O objetivo deste trabalho foi avaliar o valor nutritivo de silagens de genótipos anões e altos de capim-elefante (Pennisetum purpureum), consorciados ou não à cunhã (Clitoria ternatea). O experimento foi realizado em delineamento de blocos ao acaso, em arranjo fatorial 4x2 (quatro genótipos × dois sistemas de plantio). Os genótipos consorciados ou não à cunhã foram: IRI-381 e Elefante B, de porte alto; e Taiwan A-146 2.37 e Mott, anões. A forragem foi colhida após 60 dias de rebrota. Na silagem do capim Mott consorciado à cunhã, foram observados menores teores de lignina (78,1 g kg-1), fibra em detergente neutro (636,0 g kg-1) e proteína insolúvel em detergente neutro (13,15 g kg-1), além de maior recuperação da matéria seca (873,3 g kg-1). A silagem de Taiwan A-146 2.37 cultivado em consórcio com a leguminosa apresentou maior teor de proteína bruta (136,1 g kg-1). Em ambas as silagens, os teores de nitrogênio amoniacal foram bastante reduzidos (26,4 g kg-1). No entanto, maiores teores residuais de carboidratos solúveis em água foram observados nas silagens do consórcio (1,85 mg g-1) e do capim Mott em monocultivo (1,51 mg g-1). Além disso, houve menor digestibilidade in vitro da matéria seca (676,7 g kg-1) na silagem do consórcio. Os genótipos anões aumentam o valor nutricional da silagem de capim-elefante, comparados aos de porte alto. O consórcio com a cunhã melhora as características fermentativas da silagem, apesar de reduzir a sua digestibilidade. Portanto, a ensilagem do capim anão Mott consorciado à cunhã apresenta resultados mais promissores