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1 to 12 of 12 results
  • Long-term anaerobic digestion of microalgae grown in HRAP for wastewater treatment. Effect of microwave pretreatment

     Lopes del Rei Passos, Fabiana; Hernandez Marine, Mariona; Garcia Serrano, Joan; Ferrer Martí, Ivet
    Water research (Oxford)
    Vol. 49, p. 351-359
    DOI: 10.1016/j.watres.2013.10.013
    Date of publication: 2014-02-01
    Journal article

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    This paper describes the anaerobic digestion of microalgal biomass from high rate ponds in continuous anaerobic reactors for biogas production. With hydraulic retention times (HRT) of 15 and 20 days, the volatile solids (VS) removal did not exceed 30%, and the methane production rate ranged between 0.12 and 0.14 L CH4/L day. To improve process performance, microwave irradiation at 900 W for 3 min (specific energy similar to 70,000 kJ/kg VS) was applied as a pretreatment step. The VS removal increased to 40 and 45% at 15 and 20 days HRT, respectively. Consequently, the methane production rate increased to 0.16 and 0.20 L CH4/L day at 15 and 20 days HRT, respectively. Microscopic analysis confirmed cell wall damage, although generally without lysis, after irradiating microalgal biomass. However, the energy consumption was much higher than the extra energy production of the process. Indeed, microalgal biomass should not only be thickened but also dewatered if microwave irradiation was to be applied as a pretreatment to anaerobic digestion for biogas production. (C) 2013 Elsevier Ltd. All rights reserved.

  • Biogas production from microalgae grown in wastewater: effect of microwave pretreatment

     Lopes del Rei Passos, Fabiana; Sole, Maria; Garcia Serrano, Joan; Ferrer Martí, Ivet
    Applied energy
    Vol. 108, p. 168-175
    DOI: 10.1016/j.apenergy.2013.02.042
    Date of publication: 2013-08
    Journal article

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    The aim of this study was to evaluate the effect of microwave pretreatment on the solubilisation and anaerobic digestion of microalgae-bacterial biomass cultivated in high rate algal ponds for wastewater treatment. The microwave pretreatment comprised three specific energies (21,800, 43,600 and 65,400. kJ/kg TS), combining three output power values with different exposure times. Response surface analysis showed that the main parameter influencing biomass solubilisation was the applied specific energy. Indeed, a similar solubilisation increase was obtained for the same specific energy, regardless of the output power and exposure time (280-350% for 21,800. kJ/kg TS, 580-610% for 43,600. kJ/kg TS and 730-800% for 65,400. kJ/kg TS). In biochemical methane potential tests, the initial biogas production rate (27-75% increase) and final biogas yield (12-78% increase) were higher with pretreated biomass. A linear correlation was found between biomass solubilisation and biogas yield.

  • Impact of low temperature pretreatment on the anaerobic digestion of microalgal biomass

     Lopes del Rei Passos, Fabiana; Garcia Serrano, Joan; Ferrer Martí, Ivet
    Bioresource technology
    Vol. 138, p. 79-86
    DOI: 10.1016/j.biortech.2013.03.114
    Date of publication: 2013-06
    Journal article

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    The aim of this study was to investigate the effect of low temperature pretreatment on the anaerobic digestion of microalgal biomass grown in wastewater. To this end, microalgae were pretreated at low temperatures (55, 75 and 95. C) for 5, 10 and 15. h. Biomass solubilisation was enhanced with the pretreatment temperature and exposure time up to 10. h. The methane yield was improved by 14%, 53% and 62% at 55, 75 and 95. C, respectively; and was correlated with the solubilisation increase. The pretreatment at 95. C for 10. h increased VS solubilisation by 1188%, the initial methane production rate by 90% and final methane yield by 60% compared to untreated microalgae. With diluted biomass (~1% VS) positive energy balance was not likely to be attained. However, with concentrated biomass (2% VS) energy requirements may be covered and even surplus energy generated.

    The aim of this study was to investigate the effect of low temperature pretreatment on the anaerobic digestion of microalgal biomass grown in wastewater. To this end, microalgae were pretreated at low temperatures (55, 75 and 95 °C) for 5, 10 and 15 h. Biomass solubilisation was enhanced with the pretreatment temperature and exposure time up to 10 h. The methane yield was improved by 14%, 53% and 62% at 55, 75 and 95 °C, respectively; and was correlated with the solubilisation increase. The pretreatment at 95 °C for 10 h increased VS solubilisation by 1188%, the initial methane production rate by 90% and final methane yield by 60% compared to untreated microalgae. With diluted biomass (∼1% VS) positive energy balance was not likely to be attained. However, with concentrated biomass (>2% VS) energy requirements may be covered and even surplus energy generated.

  • Comparing pretreatment methods to improve the methane yield of microalgae grown in wastewater

     Lopes del Rei Passos, Fabiana; Ferrer Martí, Ivet
    World Congress on Anaerobic Digestion
    p. 1-5
    Presentation's date: 2013-06-26
    Presentation of work at congresses

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    Microalgae have recently drawn attention as a potential resource for biofuels generation. In the short term, anaerobic digestion seems the most viable downstream process. Still, microalgae cell wall restrains the hydrolysis, hampering the methane production potential. This work aimed at improving the anaerobic biodegradability of microalgae through different pretreatment methods: microwave, low temperature and high temperature. For the microwave pretreatment, the specific energy was the main parameter affecting biomass solubilisation, increasing up to 800 % compared to untreated biomass. For the low and high temperature pretreatments, temperature was the most important factor, increasing biomass solubilisation up to 1190 and 2140 % in each case. BMP tests showed an increased methane yield after all pretreatments (40-80 %), with the highest results for the microwave pretreatment. In semi-continuous reactors operated at 15 days HRT, the methane production was increased by 30 and 33 % after microwave and low temperature pretreatment, respectively. When increasing the HRT to 20 days, the methane yield was further enhanced by 60 and 52 % after microwave and low temperature pretreatment, respectively. Therefore, initial results showed pretreatment potential for microalgae solubilisation and methane yield improvement.

    Microalgae have recently drawn attention as a potential resource for biofuels generation. In the short term, anaerobic digestion seems the most viable downstream process. Still, microalgae cell wall restrains the hydrolysis, hampering the methane production potential. This work aimed at improving the anaerobic biodegradability of microalgae through different pretreatment methods: microwave, low temperature and high temperature. For the microwave pretreatment, the specific energy was the main parameter affecting biomass solubilisation, increasing up to 800 % compared to untreated biomass. For the low and high temperature pretreatments, temperature was the most important factor, increasing biomass solubilisation up to 1190 and 2140 % in each case. BMP tests showed an increased methane yield after all pretreatments (40-80 %), with the highest results for the microwave pretreatment. In semi-continuous reactors operated at 15 days HRT, the methane production was increased by 30 and 33 % after microwave and low temperature pretreatment, respectively. When increasing the HRT to 20 days, the methane yield was further enhanced by 60 and 52 % after microwave and low temperature pretreatment, respectively. Therefore, initial results showed pretreatment potential for microalgae solubilisation and methane yield improvement.

  • Producción de biogás a partir de microalgas cultivadas en aguas residuales

     Ferrer Martí, Ivet; Lopes del Rei Passos, Fabiana; Garcia Serrano, Joan
    Reunión de la Mesa Española de Tratamiento de Aguas
    p. 151-152
    Presentation's date: 2012-10-05
    Presentation of work at congresses

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  • Biogas production from microalgae grown in wastewater: effect of microwave pretreatment

     Lopes del Rei Passos, Fabiana; Garcia Serrano, Joan; Ferrer Martí, Ivet
    Young Algaeneers Symposium
    p. 74
    Presentation's date: 2012-06-14
    Presentation of work at congresses

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  • Microalgae production and wastewater treatment in high rate algal ponds and low-cost tubular photobioreactors

     Lopes del Rei Passos, Fabiana; Garcia Serrano, Joan; Ferrer Martí, Ivet
    Young Algaeneers Symposium
    p. 24
    Presentation's date: 2012-06-15
    Presentation of work at congresses

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  • Mechanical resistance properties of gravel used in subsurface flow constructed wetlands: implications for clogging

     Pedescoll Albacar, Anna; Lopes del Rei Passos, Fabiana; Alba, Elisenda; Garcia Serrano, Joan; Puigagut Juarez, Jaume
    Water science and technology
    Vol. 63, num. 9, p. 1801-1807
    DOI: 10.2166/wst.2011.380
    Date of publication: 2011-05-05
    Journal article

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    Gravel constitutes the filter medium in subsurface flow constructed wetlands (SSF CWs) and its porosity and hydraulic conductivity decrease over time (clogging), limiting the lifespan of the systems. Using gravel of poor quality accelerates clogging in wetlands. In this study, gravel samples from six different wetland systems were compared with regards to their mineral composition and mechanical resistance properties. Results showed that both mineralogy and texture are related to mechanical resistance. Accordingly, gravel with high content of quartz (480%) showed a lower percentage of broken particles (0.18–1.03%) than those with lower content of quartz (2.42–4.56% media broken). Although granite is formed by high durability minerals, its non-uniform texture results in a lower resistance to abrasion (ca. 10% less resistance than calcareous gravel). Therefore, it is recommended to use gravels composed mainly of quartz or, when it is not available, limestone gravels (rounded and uniform) are recommended instead. The resistance to abrasion (LAA test) seems to be a good indicator to determine the mechanical properties of gravels used in CWs. It is recommended to use gravels with LAA below 30% in order to avoid a rapid clogging due to gravel crumbling and subsequent mineral solids accumulation.

  • Bioalgas: producción de biogas a partir de biomasa algal procedente de lagunas de alta carga para la depuración de aguas residuales

     Gullon Santos, Martin; Uggetti, Enrica; Lopes del Rei Passos, Fabiana; Ferrer Martí, Ivet
    Competitive project

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  • Gravel composition related to clogging development in horizontal subsurface flow constructed wetlands  awarded activity

     Pedescoll Albacar, Anna; Lopes del Rei Passos, Fabiana; Alba, Esther; García, Joan; Puigagut Juarez, Jaume
    IWA International Conference on Wetlands Systems for Water Pollution Control
    p. 1-3
    Presentation's date: 2010-10-08
    Presentation of work at congresses

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  • Ayuda a inscripcion de investigadores de paises en vias de desarrollo y estudiantes, y a la publicación del libro de abstracts congr

     Lopes del Rei Passos, Fabiana; Carretero Ariza, Javier; Samso Campa, Roger; Garfi, Marianna; Avila Martin, Cristina; Ferrer Martí, Ivet; Alvarez San Millan, Eduardo; Cadena, Erasmo; Puigagut Juarez, Jaume; Garcia Serrano, Joan
    Competitive project

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  • 3RD WETLAND POLLULANT DYNAMICS AND CONTROL (WETPOL 2009)

     Avila Martin, Cristina; Uggetti, Enrica; Puigagut Juarez, Jaume; Cadena, Erasmo; Samso Campa, Roger; Carretero Ariza, Javier; Garfi, Marianna; Lopes del Rei Passos, Fabiana; Alvarez San Millan, Eduardo; Garcia Serrano, Joan
    Competitive project

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