Title: Photodegradation and sorption govern tetracycline removal during wastewater treatment in algal ponds
Authors: Norvill Z, Toledo-Cervantes A, Blanco S, Shilton A, Guieysse B, Muñoz R
Publication: Bioresource Technology, Volume 232, Pages 35–43
Published: May 2017
The degradation of the antibiotic tetracycline, supplied at 100 µg L−1 in domestic wastewater, was studied in an outdoor, pilot scale, high rate algal pond (HRAP). Effective operation was demonstrated with the biomass concentration and the chemical oxygen demand removal efficiency averaging 1.2 ± 0.1 gTSS L−1 and 80 ± 4%, respectively, across all operational periods. Tetracycline removal exceeded 93% and 99% when the HRAP was operated at hydraulic retention times of 4 and 7 days, respectively. Batch tests and pulse testing during HRAP operation repeatedly evidenced the significance of photodegradation as a removal mechanism. Sorption dominated tetracycline removal during the night, but accounted for less than 6% of the total pollutant removal based on sorbed tetracycline extracted from biomass. Overall, these results provide the first demonstration of efficient antibiotic removal, occurring mainly via indirect photodegradation, during relevant HRAP operation (low pollutant concentration, domestic wastewater and natural sunlight).
Title: A study of photosynthetic biogas upgrading based on a high rate algal pond under alkaline conditions: Influence of the illumination regime
Authors: Franco M, Alcántara C, Noyola A, Muñoz R, Gonzalez-Sanchez A.
Publication: Science of The Total Environment, Volume 592, Pages 419–425
Published: 15 August 2017
Microalgal-bacterial processes have emerged as environmental friendly systems for the cost-effective treatment of anaerobic effluents such as biogas and nutrients-laden digestates. Environmental parameters such as temperature, irradiation, nutrient concentration and pH effect the performance of the systems. In this paper, the potential of a microalgal-bacterial photobioreactor operated under high pH (≈ 9.5) and high alkalinity to convert biogas into biomethane was evaluated. The influence of the illumination regime (continuous light supply vs 12 h/12 h light/dark cycles) on the synthetic biogas upgrading efficiency, biomass productivity and nutrient removal efficiency was assessed in a High-Rate Algal Pond interconnected to a biogas absorption bubble column. No significant differences in the removal efficiency of CO2 and H2S (91.5 ± 2% and 99.5% ± 0.5, respectively) were recorded regardless of the illumination regime. The high fluctuations of the dissolved oxygen concentration during operation under light/dark cycles allowed to evaluate the specific growth rate and the specific partial degradation rate of the microalgae biomass by photosynthesis and respiration, respectively. The respiration reduced the net microalgae biomass productivity under light/dark cycles compared with process operation under the continuous light supply.
Title: Influence of the gas-liquid flow configuration in the absorption column on photosynthetic biogas upgrading in algal-bacterial photobioreactors
Authors: Toledo-Cervantes A, Madrid-Chirinos C, Cantera S, Lebrero R, Muñoz R
Publication: Bioresource Technology, Volume 225, Pages 336–342
Published: February 2017
The potential of an algal-bacterial system consisting of a high rate algal pond (HRAP) interconnected to an absorption column (AC) via recirculation of the cultivation broth for the upgrading of biogas and digestate was investigated. The influence of the gas-liquid flow configuration in the AC on the photosynthetic biogas upgrading process was assessed. AC operation in a co-current configuration enabled to maintain a biomass productivity of 15 g m−2 d−1, while during counter-current operation biomass productivity decreased to 8.7 ± 0.5 g m−2 d−1 as a result of trace metal limitation. A bio-methane composition complying with most international regulatory limits for injection into natural gas grids was obtained regardless of the gas-liquid flow configuration. Furthermore, the influence of the recycling liquid to biogas flowrate (L/G) ratio on bio-methane quality was assessed under both operational configurations obtaining the best composition at an L/G ratio of 0.5 and co-current flow operation.
Title: Toluene biodegradation in an algal-bacterial airlift photobioreactor: Influence of the biomass concentration and of the presence of an organic phase
Authors: Lebrero R, Angeles R, Perez R, Muñoz R
Publication: Journal of Environmental Management, Volume 183, Part 3, Pages 585–593
Published: 1 December 2016
The potential of algal-bacterial symbiosis for off-gas abatement was investigated for the first time by comparatively evaluating the performance of a bacterial (CB) and an algal-bacterial (PB) airlift bioreactors during the treatment of a 6 g m−3 toluene laden air emission. The influence of biomass concentration and of the addition of a non-aqueous phase was also investigated. A poor and fluctuating performance was recorded during the initial stages of the experiment, which was attributed to the low biomass concentration present in both reactors and to the accumulation of toxic metabolites. In this sense, an increase in the dilution rate from 0.23 to 0.45 d−1 and in biomass concentration from ∼1 to ∼5 g L−1 resulted in elimination capacities (ECs) of 300 g m−3h−1 (corresponding to removal efficiencies ∼ 90%). Microalgae activity allowed for a reduction in the emitted CO2 and an increase in dissolved O2 concentration in the PB. However, excess biomass growth over 11 g L−1 hindered light penetration and severely decreased photosynthetic activity. The addition of silicone oil at 20% (on a volume basis) stabilized system performance, leading to dissolved O2 concentrations of 7 mg L−1 and steady ECs of 320 g m−3 h−1 in the PB. The ECs here recorded were considerably higher than those previously reported in toluene-degrading bioreactors. Finally, microbial population analysis by DGGE-sequencing demonstrated the differential specialization of the microbial community in both reactors, likely resulting in different toluene degradation pathways and metabolites production.
Title: Saccharification of microalgae biomass obtained from wastewater treatment by enzymatic hydrolysis. Effect of alkaline-peroxide pretreatment
Authors: Martin-Juárez J, Lorenzo-Hernando A, Muñoz-Torre R, Blanco-Lanza S, Bolado-Rodríguez S
Publication: Bioresource Technology, Volume 218, Pages 265–271
Published: October 2016
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.
Title: The Diatom Staurosirella pinnata for Photoactive Material Production
Authors: Roberta De Angelis, Sonia Melino, Paolo Prosposito, Mauro Casalboni, Francesca Romana Lamastra, Francesca Nanni, Laura Bruno, Roberta Congestri
Publication: PLoS ONE 11(11): e0165571
Published: November 9, 2016
A native isolate of the colonial benthic diatom Staurosirella pinnata was cultivated for biosilica production. The silicified cell walls (frustules) were used as a source of homogeneous and structurally predictable porous biosilica for dye trapping and random laser applications. This was coupled with the extraction of lipids from biomass showing potential to fabricate photoactive composite materials sustainably. The strain was selected for its ease of growth in culture and harvesting. Biosilica and lipids were obtained at the end of growth in indoor photobioreactors. Frustules were structurally characterized microscopically and their chemistry analyzed with Fourier Transform Infrared Spectroscopy. Frustule capacity of binding laser dyes was evaluated on a set of frustules/Rhodamine B (Rho B) solutions and with respect to silicon dioxide and diatomite by Fluorescence Spectroscopy demonstrating a high affinity for the organic dye. The effect of dye trapping property in conveying Rho B emission to frustules, with enhancement of scattering events, was analyzed on Rho B doped polyacrylamide gels filled or not with frustules. Amplified spontaneous emission was recorded at increasing pump power indicating the onset of a random laser effect in frustule filled gels at lower power threshold compared to unfilled matrices.
Title: Microalga Nannochloropsis sp. biomass for biodiesel production: conventional (cell disruption) and in situ transesterification
Authors: Gouveia, L.; Janelas, J.; Torpecelo, A.; Oliveira, A.C.
Publication: Journal of Marine Biology & Oceanography
Published: April 19, 2016
The potential of Nannochloropsis sp. microalga to biodiesel production was assessed. The work deals with the optimization of the cell disruption, a required step when the lipid extraction followed by the transesterification reaction is the option to produce biodiesel, as well as the optimization of the reaction parameters (catalyst, alcohol, temperature and time) of the in situ transesterification (direct conversion of the saponifiable lipids into FAME – fatty acid metyl esters, usually called as biodiesel, in one step). The cell rupture of wet and dried biomass (by oven and freezedryer) using different methods (physical – coffee grinder and ball-mill; and thermodynamic – microwaves and autoclave) was evaluated. The highest lipid recovery (42.4 ± 0.2% g of lipids /g of oven dried biomass) was attained from the oven dried biomass pretreated in a coffee grinder followed by a ball milling. The microalgal oil quality (fatty acid profile, acid value and iodine value) was determined and was not influenced by the biomass state (oven or freeze-dried) nor by the cell rupture method, being mainly composed of palmitic (C16:0), palmitoleic (C16:1) and oleic (C18:1) acids. The linoleic acid (C18:3) content is quite low (< 0.35% w/w) which results in a high quality biodiesel in terms of this parameter. The viability of the in situ transesterification, in order to reduce technological challenges, energy, time, environmental negative impacts and costs of the traditional processes, was studied and optimized The most favourable conditions were found to be 3.16 g of methanol / 100 g of dry biomass, 1.2% v/v of catalyst (H2SO4), for 6 h at 50°C, which allows of 95% esters formation. In terms of the cell rupture, the coffee grinder followed by the ball mill, proved again, to be the most efficient process, promoting an increase in the transesterification reaction rate.
Title: Microalgae biomass production using wastewater: treatment and costs. Scaleup considerations
Authors: Gouveia, L.; G raça, S.; Sousa, C.; Ambrosano, L; Ribeiro, B.; Botrel E.P.; Neto, P.C.; Ferreira, Ana F.; Silva, CM.
Publication: Algal Research 16, 167–176
Published: June 2016
This work is part of a LIFE project to treat urban wastewater from Águas da Figueira (AdF, Figueira da Foz, PT) using a vertical tubular photobioreactor (PBR) prototype (150 L), to be scaled up and integrated in a waste water treatment plant (WWTP). The PBR was inoculated with three different microalgae: Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc) and Consortium C (ConsC), isolated from the effluent. The study intends to find the best microalga in terms of wastewater remediation, biomass productivity and quality, for further uses, such as biofuel, biofertilizer and bioplastic production.
Title: Capturing biodiversity: linking a cyanobacteria culture collection to the “scratchpads” virtual research environment enhances biodiversity knowledge
Authors: Spyros Gkelis, Manthos Panou
Publication: Biodiversity Data Journal 4: e7965
Published: 06 Apr 2016 (Open-Access)
Currently, cyanobacterial diversity is examined using a polyphasic approach by assessing morphological and molecular data (Komárek 2015). However, the comparison of morphological and genetic data is sometimes hindered by the lack of cultures of several cyanobacterial morphospecies and inadequate morphological data of sequenced strains (Rajaniemi et al. 2005). Furthermore, in order to evaluate the phenotypic plasticity within defined taxa, the variability observed in cultures has to be compared to the range in natural variation (Komárek and Mareš 2012). Thus, new tools are needed to aggregate, link and process data in a meaningful way, in order to properly study and understand cyanodiversity.
An online database on cyanobacteria has been created, namely the Cyanobacteria culture collection (CCC) (http://cyanobacteria.myspecies.info/) using as case studies cyanobacterial strains isolated from lakes of Greece, which are part of the AUTH culture collection (School of Biology, Aristotle University of Thessaloniki). The database hosts, for the first time, information and data such as morphology/morphometry, biogeography, phylogeny, microphotographs, distribution maps, toxicology and biochemical traits of the strains. All this data are structured managed, and presented online and are publicly accessible with a recently developed tool, namely “Scratchpads”, a taxon-centric virtual research environment allowing browsing the taxonomic classification and retrieving various kinds of relevant information for each taxon.
cyanobacteria, database, Scratchpads, taxonomy, morphology, phylogeny, biodiversity informatics
Title: EUALGAE: Microalgae proteins and ingredients
Author: Maria Hayes, Teagasc Food Research Centre, Ashtown
Publication: TResearch, Volume 11: Number 1. Spring 2016, 32‐33.
Authors: Cristina Gonzalez-Fernandez, Bruno Sialve, Beatriz Molinuevo-Salces
Publication: Bioresource Technology, 2015, 198, 896‐906.
• Microalgae biomass has a huge potential as feedstock for biogas production.
• Novel pretreatments, reactor designs and operation parameters are addressed.
• The microbial community carrying out anaerobic digestion is reviewed.
• Research on intermediate compounds exploitation is discussed.
• Integration of microalgae culture and anaerobic digestion is outlined.