Effluent organic nitrogen removal by enhanced coagulation and microfiltration

Consulta en la Biblioteca ETSI Industriales (8117)[ES] En este proyecto, el hecho de que el proceso terciario de precipitación química seguido de microfiltración es capaz de eliminar cierto porcentaje de DON de las muestras de efluente secundario de la EDAR de Stickney ha sido demostrado. Asimismo, el hecho de que la precipitación química seguida de microfiltración es un proceso efectivo y eficiente para la eliminación de fósforo ha sido comprobado a través de la experimentación. La dosis óptima de coagulante para la eliminación simultánea de DON y fósforo obtenida ha sido de 40 mg/L de sulfato de aluminio; en esta dosis los porcentajes de eliminación alcanzados han sido de 69% para el caso del DON y de 73% para el caso del fósforo. Esta dosis podrá ser empleada únicamente en las EDAR que incluyan entre sus procesos terciarios una etapa de sedimentación previa a la filtración, puesto que la filtración directa implicaría irremediablemente en este caso numerosos problemas de funcionamiento. Finalmente, un protocolo de medida para la determinación de las concentraciones de las diferentes especies de nitrógeno y fósforo presentes en las muestras de agua residual ha sido desarrollado en el laboratorio. La aportación más novedosa de dicho protocolo ha sido la inclusión de un proceso de digestión simultánea de compuestos de nitrógeno y fósforo que ha permitido una simplificación y ahorro temporal respecto a las técnicas analíticas existentes.Arnaldos Orts, M. (2009). Effluent organic nitrogen removal by enhanced coagulation and microfiltration. http://hdl.handle.net/10251/33973.Archivo delegad

INVESTIGATING THE MEDIATION OF HEMOGLOBIN PROTEINS IN NITRIFICATION AT LOW DISSOLVED OXYGEN CONDITIONS

Due to the high aeration and energy requirements of nitrifying activated sludge processes, there is great interest in developing biological nitrifying processes that operate efficiently under low dissolved oxygen (DO) conditions. In this framework, the present study has investigated the acclimation of ammonia-oxidizing communities (AOC) to low DO concentrations. Under controlled laboratory conditions, two sequencing batch reactors seeded with activated sludge from the same source were operated at high DO (near saturation) and low DO (0.1 mg O2/L) concentrations for a period of 385 days. Stable and complete nitrification at low DO after an acclimation period of approximately 140 days was demonstrated. Modeling of oxygen transfer and uptake behavior demonstrated the low DO reactor to achieve equal performance to the high DO reactor, when the latter is operated at design DO concentration (2 mg O2/L), with approximately 20 % improvement in aeration requirements and oxygen mass transfer efficiency. The effect of DO on AOC dynamics was evaluated using the 16S rRNA gene as the basis for phylogenetic comparisons and organism quantification. Ammonium consumption by ammonia-oxidizing archaea and anaerobic ammonia-oxidizing bacteria was ruled out in both reactors. Even though N. europaea was the dominant AOB lineage in both SBRs at the end of operation, this enrichment could not be linked to acclimation to oxygen-limited conditions. This finding challenges the hypothesis that low DO conditions select for ammonia-oxidizing lineages characterized by high oxygen affinities, and points to the alternative mechanism of a physiological change of a generalist nitrifying community. Acclimation brought about increased specific oxygen uptake rates and enhanced expression of a particular heme protein in the soluble fraction of the biomass in the low DO reactor as compared to the high DO reactor. The heme protein induced was determined not to be any of the enzymes playing a role in ammonia metabolism of ammonia oxidizing bacteria, including a soluble oxidase and soluble peroxidase of unknown function. Further molecular studies are required to verify the hypothesis put forward in this study that the heme protein detected is a hemoglobin.PH.D in Environmental Engineering, December 201

Understanding the effects of bulk mixing on the determination of the affinity index : consequences for process operation and design

The main objective of this study is to demonstrate the importance of mixing conditions as a source of inconsistencies between half-saturation indices in comparable systems (e.g. conventional activated sludge, membrane bioreactor) when operated at different conditions or different scales. As proof-of-principle, an exemplary system consisting of the second vessel of a hybrid respirometer has been studied. The system has been modeled both using an integrated computational fluid dynamics (CFD)biokinetic model (assumed to represent the physical system) and a tanks-in-series, completely stirred tank reactor biokinetic model (representing the applied model). The results show that different mixing conditions cause deviations in the half-saturation indices calculated when matching the applied model to the physical system performance. Additionally, sensor location has been shown to impact the calculation of half-saturation indices in the respirometric system. This will only become more pronounced at larger scales. Thus, mixing conditions clearly affect operation and design of wastewater treatment reactors operated at low substrate concentrations. Both operation and design can be improvedwith the development and application of integrated CFD-biokinetic or compartmental models

How well-mixed is well mixed? : hydrodynamic-biokinetic model integration in an aerated tank of a full-scale water resource recovery facility

Current water resource recovery facility (WRRF) models only consider local concentration variations caused by inadequate mixing to a very limited extent, which often leads to a need for (rigorous) calibration. The main objective of this study is to visualize local impacts of mixing by developing an integrated hydrodynamic-biokinetic model for an aeration compartment of a full-scale WRRF. Such a model is able to predict local variations in concentrations and thus allows judging their importance at a process level. In order to achieve this, full-scale hydrodynamics have been simulated using computational fluid dynamics (CFD) through a detailed description of the gas and liquid phases and validated experimentally. In a second step, full ASM1 biokinetic model was integrated with the CFD model to account for the impact of mixing at the process level. The integrated model was subsequently used to evaluate effects of changing influent and aeration flows on process performance. Regions of poor mixing resulting in non-uniform substrate distributions were observed even in areas commonly assumed to be well-mixed. The concept of concentration distribution plots was introduced to quantify and clearly present spatial variations in local process concentrations. Moreover, the results of the CFD-biokinetic model were concisely compared with a conventional tanks-in-series (TIS) approach. It was found that TIS model needs calibration and a single parameter set does not suffice to describe the system under both dry and wet weather conditions. Finally, it was concluded that local mixing conditions have significant consequences in terms of optimal sensor location, control system design and process evaluation

Hydrodynamic and hydrochemical characterization of acid mine drainage flowing from a metallic waste rock pile (Iberian Pyrite Belt, Spain)

La intensa actividad minera que ha tenido lugar en la Faja Pirítica Ibérica desde tiempos históricos ha dado lugar a numerosas y extensas escombreras ricas en sulfuros. El agua de lluvia se infiltra y circula a través de estos materiales. Cuando dichas aguas vuelven a la superficie, lo hacen transformadas en drenajes ácidos de mina. Este trabajo muestra una caracterización preliminar de los drenajes desde un punto de vista hidroquímico e hidrodinámico, utilizando para ello una escombrera minera abandonada situada en la zona central de la provincia de Huelva. Los caudales de descarga han sido variables (0,1-12,2 L/s) y están condicionados por el régimen pluviométrico. La respuesta hidrodinámica de la escombrera a las lluvias es relativamente rápida y en ausencia de precipitaciones los caudales tienden a ser progresivamente menores. La recarga de la escombrera por la infiltración del agua de lluvia provoca, en general, el drenaje de aguas más mineralizadas debido, principalmente, al aumento de los contenidos en SO4 , Fe, Al y Mg. El pH del agua ha sido muy ácido (2,4-2,6) y su evolución temporal no parece guardar relación con la recarga. El potencial redox ha mostrado siempre valores muy positivos, propios de condiciones oxidantesA long history of metalliferous mining has left the Iberian Pyrite Belt sulphide province with a legacy of numerous and enormous sulphide-bearing waste rock piles and tailings. Rainwater infiltrates and circulates through the waste rocks. These waters flow out of the mine dumps transformed into acid mine drainages (AMD). This work presents a preliminary hydrochemical and hydrodynamic characterization of AMD using an abandoned waste rock pile located in the central area of the Huelva province (SW Spain) as pilot site. Results show variable (0.1-12.2 L/s) and rainfall-dependent discharge flows which respond quite rapidly to precipitations. During the dry season discharge flows are progressively lower. Recharge produced by the infiltration of rainwater provokes, in general, the drainage of more mineralized waters mainly due to increased contents of SO4 , Fe, Al and Mg. Water pH has been low (2.4-2.6), with no evident relationship with recharge. Redox potential has shown oxidizing conditions in all samples along the monitoring perio