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Posadas E.,University of Valladolid | Szpak D.,University of Valladolid | Lombo F.,University of Oviedo | Dominguez A.,Biogas Fuel Cell S.A. | And 5 more authors.
Journal of Applied Phycology

The present research was conducted to simultaneously optimize biogas upgrading and carbon and nutrient removal from centrates in a 180-L high-rate algal pond interconnected to an external CO2 absorption unit. Different biogas and centrate supply strategies were assessed to increase biomass lipid content. Results showed 99 % CO2 removal efficiencies from simulated biogas at liquid recirculation rates in the absorption column of 9.9 m3 m−2 h−1, concomitant with nitrogen and phosphorus removal efficiencies of 100 and 82 %, respectively, using a 1:70 diluted centrate at a hydraulic retention time of 7 days. The lipid content of the harvested algal–bacterial biomass remained low (2.9–11.2 %) regardless of the operational conditions, with no particular trend over time. The good settling characteristics of the algal–bacterial flocs resulted in harvesting efficiencies over 95 %, which represents a cost-effective alternative for algal biomass reutilization compared to conventional physical–chemical techniques. Finally, high microalgae biodiversity was found regardless of the operational conditions. © 2015 Springer Science+Business Media Dordrecht Source

Kahlert M.,Swedish University of Agricultural Sciences | Acs E.,Danube Research Institute | Almeida S.F.P.,University of Aveiro | Blanco S.,University of Leon | And 9 more authors.

Investigations on organism ecology, biodiversity and biogeography often use large compiled datasets to extract information on species ecological preferences, which then can be used in environmental assessment. Freshwater benthic diatoms are commonly used in this context. However, it is important that the taxonomic information of the separate diatom datasets is compatible. At present, inconsistencies between diatom datasets, mainly due to differences and uncertainties in diatom identification, may misinform diatom taxon-specific ecological preferences, geographical distribution and water quality assessment. It is our opinion that these inconsistencies in diatom datasets can be reduced with quality assurance (QA), such as identification exercises. However, the results of these exercises must be well documented and well communicated; otherwise, gained knowledge may not spread inter-regionally or internationally. As a first step to reach greater consistency in QA/harmonization studies, this article (1) presents and compares information of existing diatom identification and counting QA from published and grey (non-peer reviewed) European literature to identify advantages and drawbacks of each approach; (2) summarizes taxa that can easily be misidentified according to European identification exercises; and (3) suggests a consistent design of identification exercises for diatom dataset QA. © 2016, Springer International Publishing Switzerland. Source

Martin Juarez J.,University of Valladolid | Lorenzo Hernando A.,University of Valladolid | Munoz Torre R.,University of Valladolid | Blanco Lanza S.,The Institute of the Environment | And 2 more authors.
Bioresource Technology

An enzymatic method for the carbohydrate hydrolysis of different microalgae biomass cultivated in domestic (DWB) and pig manure (PMWB) wastewaters, at different storage conditions (fresh, freeze-dried and reconstituted), was evaluated. The DWB provided sugars yields between 40 and 63%, although low xylose yields (< 23.5%). Approximately 2% of this biomass was converted to byproducts as succinic, acetic and formic acids. For PMWB, a high fraction of the sugars (up to 87%) was extracted, but mainly converted into acetic, butyric and formic acids, which was attributed to the bacterial action. In addition, the performance of an alkaline-peroxide pretreatment, conducted for 1 h, 50 °C and H2O2 concentrations from 1 to 7.5% (w/w), was essayed. The hydrolysis of pretreated microalgae supported a wide range of sugars extraction for DWB (55-90%), and 100% for PMWB. Nevertheless, a large fraction of these sugars (~30% for DWB and 100% for PMWB) was transformed to byproducts. © 2016 Elsevier Ltd. Source

Liu B.,JiShou University | Liu B.,Xiamen University | Blanco S.,University of Leon | Blanco S.,The Institute of the Environment | Huang B.,Xiamen University

Two new species in the diatom genus Nitzschia were found in the middle intertidal zone, Xiamen Bay, southern China. Both new taxa belong to the subgenus Nitzschia, as inferred from the presence of a canal-raphe-conopeum system. The valves of both new species are dorsiventral. In Nitzschia arierae sp. nov., the raphe system is positioned centrally, the conopea fuse to the valve face at supporting points, and the zone of valve face subtended by the conopeum has areolae. In Nitzschia gaoi sp. nov., the raphe system is centrally positioned or slightly eccentric, two large conopea extend out from near the raphe while two small conopea extend out from each transverse costa and cover the striae, most part of the zone of valve face subtended by the conopeum has no areolae, and there are two long produced rostrate apices that both arch toward the ventral side or one apex arches and the other is straight. Both new species are epipelic forms inhabiting the coastal environment. © 2015 Magnolia Press. Source

Toledo-Cervantes A.,University of Valladolid | Serejo M.L.,Federal University of Mato Grosso do Sul | Blanco S.,University of Leon | Blanco S.,The Institute of the Environment | And 3 more authors.
Algal Research

A pilot high rate algal pond (HRAP) interconnected to an external CO2-H2S absorption column via settled broth recirculation was used to simultaneously treat a synthetic digestate and to upgrade biogas to a bio-methane with sufficient quality to be injected into natural gas grids. An innovative HRAP operational strategy with biomass recirculation based on the control of algal-bacterial biomass productivity (2.2, 4.4 and 7.5 g m-2 d-1) via settled biomass wastage was evaluated in order to enhance nutrient recovery from digestate at a constant hydraulic retention time. The influence of the recycling liquid to biogas (L/G) ratio on the quality of the upgraded biogas was assessed. The bio-methane composition under a L/G ratio of 1 (0.4 ± 0.1% CO2, 0.03 ± 0.04% O2, 2.4 ± 0.2% N2 and 97.2 ± 0.2% CH4) complied with the technical specifications of most European bio-methane legislations regardless of the biomass productivity established. The HRAP operational strategy applied allowed increasing the N and P recovery from 19 and 22% to 83 and 100%, respectively, when the biomass productivity was increased from 2.2 to 7.5 g m-2 d-1. Finally, the dynamics of microalgae and bacteria population structure were characterized by morphological identification and Denaturing Gradient Gel Electrophoresis analysis. © 2016 Elsevier B.V. Source

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