Desarrollo de una nueva tecnología de eliminación de nitrógeno basada en procesos de nitrificación parcial-anammox mediante biofiltración en lecho fijo

Laburpena

ABSTRACT Currently, the most common methods of treating wastewater rich in nitrogen in wastewater treatment plants are biological methods based on nitrification-denitrification process. These methods involve high operating costs that could be reduced with the use of new biotechnologies. In recent years several processes based on autotrophic nitrogen removal have been proposed in wastewater treatment. These technologies are based on a partial nitrification of ammonium nitrite and an anaerobic ammonium oxidation. The combination of both biological processes result in a system in which ammonia is oxidized to molecular nitrogen directly without going through the intermediate form of the nitrate, and an external source of organic carbon is not needed. In this context, a novel technology based on Anammox processes (Anaerobic Ammonium Oxidation), called Canon (Completely Autotrophic Nitrogen removal Over Nitrite) has been evaluated. Canon process is characterized by being carried out in a single reactor and under microaerophilic conditions which makes it a more cost effective and a friendly solution with environment. The process has been developed under the configuration of a fixed bed biofilter using Filtralite as support material. This technology does not currently exist in the market. So it has led to the patent by the research team of this investigation. Throughout the investigation, we have studied the structure of the bacterial community as well as removal efficiencies of nitrogen in various laboratory scale bioreactors working under different conditions in various experiments. Along the work developed startup and stability of biomass in bioreactors has been optimized. It must be kept in mind that the boot process of these systems is slow due to the low reproductive rate of the specific bacteria of these systems. Because microbial populations involved in these nitrogen removal systems are very sensitive to any change in operating and / or environmental conditions, in this thesis the response of this technology under stressful conditions for these organisms has been investigated. So, two cases that significantly affect autotrophic nitrogen removal populations have been studied, such as the presence of organic matter in the influent and the treatment of saline influent. In both cases, the efficiency results have been very satisfactory. The development of a microbial consortium with different metabolisms due to the coexistence of different bacterial populations as AOB, Anammox and Denitrifying heterotrophic has been observed. This has increased awareness of the microbial community response and subsequent operation of this bioprocess under different operating conditions. Ultimately, the results of this research may be important to implement full-scale Canon system plants using fixed-bed biofiltration technology.