Aplicación de Nitrosomonas y Nitrobacter en forma de biopelícula para la nitrificación biológica en reactores de lecho fijo
The present work has been developed in the frame of the MELISSA project (Micro Ecological LIfe Support System Alternative) of the European Space Agency (ESA). The aim of the project is the design of a Life Support System based in microorganisms, to manage the atmosphere from the transformation of the generated wastes into edible matter. A part of the project is a biological nitrifying bioreactor, which is developed in the present work. A complete characterisation of the operation of the biofilm nitrification process in fixed bed reactors has been carried out. To this purpose, a pilot reactor (8 L of total volume) and three bench reactors (0.65 L of total volume) with immobilised biomass (Nitrosomonas europaea, ATCC 19718 and Nitrobacter winogradskyi, ATCC 25391) onto the surface of polystyrene beads (Biostyr®, used as physical support of the bacteria) were used.
In the part of reactor development, the basic instrumentation and control configuration of the main biotechnological variables that have direct influence in the biofilm nitrification process were implemented: pH, temperature, dissolved oxygen, pressure, level control, etc. To go deeply into the study of the behaviour of these reactors, a physical characterisation was carried out. Mainly, the liquid phase mixing and the oxygen mass transfer coefficient from the gas to the liquid phase were studied. After this, a mathematical model was defined and validated in order to describe the liquid phase mixing in the fixed bed reactors used.
Biological nitrifying experiments operating in continuous mode were carried out using both, pilot and bench reactors, to determine the effect of the main variables that have strong influence on the process: ammonium input load, temperature and dissolved oxygen. From the analysis of the experiments, a dynamic model that allow the proper description and interpretation of the experimental results obtained has been defined and validated. This model provides a suitable description of the system response against perturbations in the ammonium load, due to changes in the residence time used or, on the other hand, after variations in the input ammonium concentration.
Advisor:Francesc Gòdia Casablancas; José Luis Montesinos
School:Universitat Autónoma de Barcelona
Source Type:Master's Thesis
Keywords:447 departament d enginyeria quimica
Date of Publication:06/21/2001