Influencia de las características físicas y químicas del licor de mezcla en Bioreactores de Membrana y su correlación con los parámetros de operación en aguas residuales urbanas e industriales
In this Doctoral Thesis the study of the influence of the operating parameters of the activated sludge process on the physical and chemical characteristics of the mixed liquor, from different membrane bioreactors (MBR), has been carried out. In addition, an optical characterization of the mixing liq...
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| Formato: | tesis doctoral |
| Fecha de publicación: | 2017 |
| País: | España |
| Recursos: | Universitat Politècnica de València (UPV) |
| Repositorio: | RiuNet. Repositorio Institucional de la Universitat Politécnica de Valéncia |
| Idioma: | español |
| OAI Identifier: | oai:riunet.upv.es:10251/90512 |
| Acesso em linha: | https://riunet.upv.es/handle/10251/90512 |
| Access Level: | acceso abierto |
| Palavra-chave: | Biorreactor de Membranas (MBR) Sustancias Poliméricas Extracelulares (EPS) Productos Solubles Microbianos (SMP) Fouling INGENIERIA QUIMICA |
| Resumo: | In this Doctoral Thesis the study of the influence of the operating parameters of the activated sludge process on the physical and chemical characteristics of the mixed liquor, from different membrane bioreactors (MBR), has been carried out. In addition, an optical characterization of the mixing liquor has been performed. In order to achieve the above mentioned aim, samples of the mixed liquor from an MBR treating municipal wastewater were first analysed and then, the characteristics of two MBR mixed liquors treating the leachates from two treatment plants of the organic fraction of municipal solid waste (OFMSW) were evaluated. It is noteworthy that the difference between the two industrial MBR lies on the feeding (inlet) to the MBR, which is determined by the treatment performed to the OFMSW, since one of them consists of a wet anaerobic digestion (MBR-LS) and the other of a dry anaerobic digestion (MBR-HS), so that the latter leachate contains higher concentration of suspended solids in its composition. For the chemical characterization of the mixture liquor, the extracellular polymeric substances (EPS) have been analysed. EPS are formed by the sum of extracted extracellular polymeric substances (eEPS) and soluble microbial products (SMP). These substances are considered the main cause of membranes fouling in MBRs and are basically formed by proteins and polysaccharides, which can be both attached to the cell wall and outside the cell, in form of eEPS or SMP. Regarding the physical characterization, in particular it has been analysed and studied the effect on the membrane fouling of the total and volatile suspended solids, the viscosity, the capillary suction time and the particle size, measured through the resistance to filtration. Finally, in the municipal MBR, cell viability with epifluorescence microscopy has been studied, as well as the main components of EPS have been stained by two different methods. In addition, a statistical study has evaluated the effect of the main operating parameters of the MBR on the characterization parameters of the mixed liquor. By means of least squares regression, the operational parameters that influence SMP production in industrial MBR have been studied. The study was completed by evaluating the fouling of an ultrafiltration membrane with proteins extracted from EPS and subsequently purified with ammonium sulphate at different pH values. To this end, different synthetic proteins (bovine serum albumin, casein, haemoglobin and lysozyme) were first analysed and then compared with the proteins extracted from the mixed liquor. Membrane fouling with purified eEPS proteins has also been studied along with sodium alginate added in the same concentration as the proteins. The results obtained demonstrate, firstly, that SMP play an important role in the membrane fouling. The concentration of proteins has been considerably higher than that of carbohydrates both in SMP and in eEPS, although SMP influenced to a greater extent on the filtration of the activated sludge. In addition, it is shown that bacteria under stress conditions, caused for example by increase in conductivity, increase the production of SMP, and therefore, membrane fouling increases. On the other hand, it is concluded that a low hydraulic retention time favours a high carbohydrates concentration and consequently drives to an increase in the viscosity and capillary suction time, also increasing the membrane fouling. |
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