Depuración de vinazas digeridas y purificación de biogás mediante sistemas de algas-bscterias

La intensa producción mundial de la industria agroalimentaria genera una gran cantidad de aguas residuales, las cuales se caracterizan por una elevada concentración de nutrientes y materia orgánica. Específicamente, las aguas procedentes de la fermentación de las melazas de la industria azucarera (vinazas) son unas de las más contaminantes. En este contexto, los sistemas de lagunaje algas-bacterias se han perfilado como una de las mejores técnicas para la eliminación de estos nutrientes, permitiendo además la purificación simultánea de biogás y un aprovechamiento de la biomasa algal generada. En el presente trabajo se estudió la aplicación de un fotobiorreactor de lagunaje de algas y bacterias (high rate algal pond, HRAP) de 180 L interconectado a una columna externa de absorción de CO2 de 2.5 L desde Marzo de 2014 hasta Junio de 2014 (73 días), para evaluar de manera simultánea la eliminación de nutrientes en vinazas, la purificación de biogás y la caracterización de la biomasa algal para obtener productos de valor añadido. La vinaza con la que se trabajó se diluyó 10 veces con agua del grifo y se alimentó continuamente al sistema con un tiempo de retención hidráulico de 7 días. El trabajo se desarrolló en dos etapas diferentes, centrándose la primera exclusivamente en la depuración de las vinazas, mientras que en la segunda se estudió la depuración de las vinazas en el fotobiorreactor conectado a la columna de absorción de biogás sintético (30% de CO2) alimentada con un flujo de biogás de 5 mL/min y una recirculación de líquido desde el HRAP de 125 L/d. Los resultados mostraron un déficit de carbono en la vinaza tratada inicialmente. De esta manera, sólo cuando se conectó la columna de absorción se tuvo una eliminación efectiva de nutrientes (37±7% de NT y 39.0±3.3% de P) y se produjo un aumento de concentración de sólidos suspendidos totales en el HRAP desde 0.18 g/L hasta 0.56 g/L (en parte debido también a las mayores tasas de evaporación). La alta tasa de oxigenación en el sistema conllevó una nitrificación rápida del N-NH4 + alimentado, siendo su eliminación superior al 94%, sin tener influencia el mayor aporte de carbono inorgánico en la etapa II: La eliminación de carbono sí que fue efectivaindependientemente de la etapa estudiada, eliminándose toda la fracción biodegradable de carbono orgánico (máximo de 45±11% en la segunda etapa), y con eliminaciones 7 máximas de carbono inorgánico del 70.5±0.5 % en la primera etapa de estudio. La eliminación de CO2 del biogás sintético alimentado fue del 99.1±0.2%. La recogida de la biomasa en el sedimentador instalado tras el HRAP fue efectiva (≥94%). Esta biomasa se caracterizó por tener altos contenidos de hidratos de carbono (81.8±1.3 y 74.8±3.5% en las etapas I y II, respectivamente), lo que sugiere una efectiva producción de bioetanol a partir de la misma tras la extracción e hidrólisis de azucares y su posterior fermentación, permitiendo de esta manera el concepto de biorefinería como una realidad emergente.Departamento de Ingeniería Química y Tecnología del Medio AmbienteMáster en Ingeniería Ambienta

Experience with PV-diesel hybrid village power systems in southern Morocco

In October 2002, under the auspices of Spanish Cooperation, a pilot electrification project put into operation two centralised PV-diesel hybrid systems in two different Moroccan villages. These systems currently provide a full-time energy service and supply electricity to more than a hundred of families, six community buildings, street lighting and one running water system. The appearance of the electricity service is very similar to an urban one: one phase AC supply (230V/50Hz) distributed up to each dwelling using a low-voltage mini-grid, which has been designed to be fully compatible with a future arrival of the utility grid. The management of this electricity service is based on a “fee-for-service” scheme agreed between a local NGO, partner of the project, and electricity associations created in each village, which are in charge of, among other tasks, recording the daily energy production of systems and the monthly energy consumption of each house. This register of data allows a systematic evaluation of both the system performance and the energy consumption of users. Now, after four years of operation, this paper presents the experience of this pilot electrification project and draws lessons that can be useful for designing, managing and sizing this type of small village PV-hybrid syste

Tracking and back-tracking

This paper presents a review of back-tracking geometry not only for single axis but also for two-axis tracking and analyses the corresponding energy gains. It compares the different back-tracking strategies with the ideal tracking in terms of energy yield concluding, on the one hand, that back-tracking is more useful for single horizontal axis than for the single vertical one, and on the other hand, that back-tracking is more efficient when applied in the primary axis of a two-axis tracke

Testing of fluorescent DC lamps for Solar Home Systems

With the advent of the Universal Technical Standard for Solar Home Systems, procedures to test the compliance of SHS fluorescent lamps with the standard have been developed. Definition of the laboratory testing procedures is a necessary step in any lamp quality assurance procedure. Particular attention has been paid to test simplicity and to affordability, in order to facilitate local application of the testing procedures, for example by the organisations which carry out electrification programmes. The set of test procedures has been applied to a representative collection of 42 lamps from many different countries, directly acquired in the current photovoltaic rural electrification market. Tests apply to: lamp resistance under normal operating conditions; lamp reliability under extreme conditions; under abnormal conditions; and lamp luminosity. Results are discussed and some recommendations for updating the relevant standard are given. The selected technical standard, together with the proposed testing procedures, form the basis of a complete quality assurance tool that can be applied locally in normal electrical laboratories. Full testing of a lamp requires less than one month, which is very reasonable on the context of quality assurance programme

"Del estudio en la theórica y del trabajo en la práctica" observaciones sobre la formación, ideas y obra del arquitecto Vicente Acero

Vicente Acero continúa siendo un arquitecto infravalorado, a pesar de que intervino en la construcción de algunas de las más representativas creaciones del Barroco español, como pueden ser los sagrarios de las cartujas de Granada y El Paular, la Catedral de Cádiz, la fachada de la Catedral de Guadix, etc. En estas líneas analizamos las circunstancias y motivaciones que orientan su siempre difícil labor; atendiendo a su formación como cantero, la influencia y participación en las obras de su maestro Francisco Hurtado, los contactos con los ingenieros militares, los préstamos visibles de la arquitectura barroco italiana al igual que, a la luz de nuevos datos, profundizamos en sus conocimientos teóricos

A 800 kW I-V curve

This paper presents the measurement of the I-V curve of an 800 kW PV generator by means of an own-made capacitive load. Along the lines of some previous works, it is shown that an I-V curve analysis can also be applied to big PV generators and that, when measuring the operating conditions with reference modules and taking some precautions (especially regarding the operating cell temperature), it is still a useful tool for characterizing them and therefore can be incorporated into maintenance procedures. As far as we know, this is the largest I-V curve measured so far

Prevalence of functional disability in activities of daily living (ADL), instrumental activities of daily living (IADL) and associated factors, as predictors of morbidity and mortality

[Abstract] The aim of this study is to establish the existing relationship among variables referred to the person, specifically age and gender, and the functional dependence in basic ADL and in IADL, as well as the possible relationship it has with the increase of morbidity and mortality in a random sample of 598 individuals older than 65 years. Of these individuals, 34.6% were categorized as dependent for at least one ADL, and 53.5% if we refer to IADL. Regarding the ADL, the risk of dependence increases (odds ratio = OR = 1.089) per year of age, (OR = 2.48) in women’s case; while there is an IADL correlation between age and the score (r = +- 0.527; p < 0.001). A relationship exists between dependence and the days of hospitalization (for ADL: r = +- 0.12, p = 0.018 and IADL: r = +- 0.97, p = 0.003), the number of visits to the doctor (ADL: r = +- 0.27, p < 0.001; IADL: r = +- 0.25, p < 0.001) or the presence of concomitant pathologies such as dementia (ADL: p < 0.001; IADL: p < 0.001). There is a significant association between age, gender and dependence, as well as between dependence and morbidity and mortality, so that dependence could be used as a predictor of both

Cognitive impairment as predictor of functional dependence in an elderly sample

[Abstract] This retrospective study determines the role of cognitive decline as a predictor of functional dependence. In a representative 600 community-dwellers aged 65 or older, we examined using a logistic regression model, the association between cognitive status (taking into account age and educational level) and dependence on basic and instrumental activities of daily living (ADL and IADL, resp.), controlling for socio-demographic variables and health conditions. The Mini-Mental State Examination (MMSE) scores were compared in participants with functional disability to perform basic and instrumental activities. Cognitive status influenced functional dependence on activities of daily living, basic (OR = 4.1, 95%CI = 2.7–6.1) and instrumental (OR = 5.7, 95%CI = 3.5–9.3), independently of gender, age, educational level and health conditions. Besides, cognitive impairment was associated with the dependence on certain basic (e.g., bathing, toileting) and instrumental (e.g., using the telephone, taking medications, and handling finances) activities. This was a gradual relationship, the highest cognitive decline implied the highest loss of ability at carrying out activities, with a larger impact on basic activities. These findings suggest that cognitive decline can be a predictor for functional dependence, independently of other variables, and turn into a very useful tool indicating the need for support