411 research outputs found

    Preliminary data set to assess the performance of an outdoor membrane photobioreactor

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    [EN] This data in brief (DIB) article is related to a Research article entitled 'Optimising an outdoor membrane photobioreactor for tertiary sewage treatment' [1]. Data related to the effect of substrate turbidity, the ammonium concentration at which the culture reaches nitrogen-deplete conditions and the microalgae growth rate under outdoor conditions is provided. Microalgae growth rates under different substrate turbidity were obtained to assess the reduction of the culture's light availability. Lab-scale experiments showed growth rates reductions of 22-44%. Respirometric tests were carried to know the limiting ammonium concentration in thismicroalgae-basedwastewater treatment system. Growth rates (m) of green microalgae Scenedesmus and Chlorella obtained under outdoor conditions; i.e. 0.40 d(-1) (R-2 = 0.993) and 0.43 d(-1) (R-2 = 0.995), respectively, can be useful to obtain optimum operating conditions of membrane photobioreactor (MPBR).This research work was supported by the Spanish Ministry of Economy and Competitiveness (MINECO, Projects CTM2014-54980-C2-1-R and CTM2014-54980-C2-2-R) jointly with the European Regional Development Fund (ERDF), which are gratefully acknowledged. It also received support from the Spanish Ministry of Education, Culture and Sport via a pre-doctoral FPU fellowship to the first author (FPU14/05082).Gonzalez-Camejo, J.; Jiménez Benítez, AL.; Ruano, MV.; Robles Martínez, Á.; Barat, R.; Ferrer, J. (2019). Preliminary data set to assess the performance of an outdoor membrane photobioreactor. Data in Brief. 27:1-7. https://doi.org/10.1016/j.dib.2019.104599S172

    Anaerobic biodegradation of oleic and palmitic acids : evidence of mass transfer limitations caused by long chain fatty acid accumulation onto the anaerobic sludge

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    Palmitic acid was the main long chain fatty acids (LCFA) that accumulated onto the anaerobic sludge when oleic acid was fed to an EGSB reactor. The conversion between oleic and palmitic acid was linked to the biological activity. When palmitic acid was fed to an EGSB reactor it represented also the main LCFA that accumulated onto the sludge. The way of palmitic acid accumulation was different in the oleic and in the palmitic acid fed reactors.Whenoleic acid was fed, the biomass-associated LCFA (83% as palmitic acid) were mainly adsorbed and entrapped in the sludge that became ‘‘encapsulated’’ by an LCFA layer. However, when palmitic acid was fed, the biomass-associated LCFA (the totality as palmitic acid) was mainly precipitated in white spots like precipitates in between the sludge, which remained ‘‘non-encapsulated.’’ The two sludges were compared in terms of the specific methanogenic activity (SMA) in the presence of acetate, propionate, butyrate, and H2CO2, before and after the mineralization of similar amounts of biomassassociated LCFA (4.6 and 5.2 g COD-LCFA/g of volatile suspended solids (VSS), for the oleic and palmitic acid fed sludge, respectively). The ‘‘non-encapsulated,’’ sludge exhibited a considerable initial methanogenic activity on all the tested substrates, with the single exception of butyrate. However, with the ‘‘encapsulated’’ sludge only methane production from ethanol andH2/CO2 was detected, after a lag phase of about 50 h. After mineralization of the biomass-associated LCFA, both sludges exhibited activities of similar order of magnitude in the presence of the same individual substrates and significantly higher than before. The results evidenced that LCFA accumulation onto the sludge can create a physical barrier and hinder the transfer of substrates and products, inducing a delay on the initial methane production. Whatever the mechanism, metabolic or physical, that is behind this inhibition, it is reversible, being eliminated after the depletion of the biomass-associated LCFA.Fundação para a CiĂȘncia e Tecnologia (FCT) Fundo Social Europeu (FSE

    Efficacy of different antifouling treatments for seawater cooling systems

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    In an industrial seawater cooling system, the effects of three different antifouling treatments, viz. sodium hypochlorite (NaClO), aliphatic amines (Mexel1432) and UV radiation, on the characteristics of the fouling formed were evaluated. For this study a portable pilot plant, as a side-stream monitoring system and seawater cooling system, was employed. The pilot plant simulated a power plant steam condenser, having four titanium tubes under different treatment patterns, where fouling progression could be monitored. The nature of the fouling obtained was chiefly inorganic, showing a clear dependence on the antifouling treatment employed. After 72 days the tubes under treatment showed a reduction in the heat transfer resistance (R) of around 70% for NaClO, 48% for aliphatic amines and 55% for UV, with respect to the untreated tube. The use of a logistic model was very useful for predicting the fouling progression and the maximum asymptotic value of the increment in the heat transfer resistance (DRmax). The apparent thermal conductivity (l) of the fouling layer showed a direct relationship with the percentage of organic matter in the collected fouling. The characteristics and mode of action of the different treatments used led to fouling with diverse physicochemical properties

    Sodium dodecyl sulfate allows the persistence and recovery of biofilms of Pseudomonas fluorescens formed under different hydrodynamic conditions

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    The effect of the anionic surfactant sodium dodecyl sulfate (SDS) on Pseudomonas fluorescens biofilms was investigated using flow cell reactors with stainless steel substrata, under turbulent (Re=5200) and laminar (Re=2000) flow. Steady-state biofilms were exposed to SDS in single doses (0.5, 1, 3 and 7 mM) and biofilm respiratory activity and mass measured at 0, 3, 7 and 12 h after the SDS application. The effect of SDS on biofilm mechanical stability was assessed using a rotating bioreactor. Whilst high concentrations (7 mM) of SDS promoted significant biofilm inactivation, it did not significantly reduce biofouling. Turbulent and laminar flow-generated biofilms had comparable susceptibility to SDS application. Following SDS exposure, biofilms rapidly recovered over the following 12 h, achieving higher respiratory activity values than before treatment. This phenomenon of posttreatment recovery was more pronounced for turbulent flow-generated biofilms, with an increase in SDS concentration. The mechanical stability of the biofilms increased with surfactant application, except for SDS concentrations near the critical micellar concentration, as measured by biofilm removal due to an increase in external shear stress forces. The data suggest that although SDS exerts antimicrobial action against P. fluorescens biofilms, even if only partial and reversible, it had only limited antifouling efficacy, increasing biofilm mechanical stability at low concentrations and allowing significant and rapid recovery of turbulent flow-generated biofilms.Fundação para a CiĂȘncia e a Tecnologia (FCT

    Fed-batch fermentation of olive mill wastewaters for lipase production

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    In the Mediterranean basin countries, huge amounts of olive mill wastewaters (OMW) are produced by the olive oil industry. It constitutes a serious environmental problem, nevertheless its composition turns OMW into a potential growth medium to lipolytic microorganisms. The aim of this work was to study lipase production as well as OMW degradation in fed-batch cultures of Candida cylindracea CBS 7869, Candida rugosa CBS 2275 and Yarrowia lipolytica W29 (ATCC 20460). Besides the improvement of lipase production, the fed-batch approach enhanced the effluent degradation, since it led to good COD and lipids reduction, both higher than 50%. C. rugosa achieved the highest value of lipase productivity (130 U L−1 h−1), in parallel with highest lipids reduction (77%). This study demonstrates thatOMWare becoming a competitive and valuable growth medium in fermentation processes with lipolytic microorganisms. The fed-batch strategy used proved to be an efficient approach to enhance lipase production from OMW and to reduce significantly the final organic load of the medium.The authors acknowledge the financial support provided by 'Fundacao para a Ciencia e Tecnologia' (Project PTDC/AMB/69379/2006; Grant SFRH/BD/27915/2006)

    Long-term acclimation of anaerobic sludges for high-rate methanogenesis from LCFA

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    Inhibition of methanogens by long chain fatty acids (LCFA) and the low numbers of LCFA-degrading bacteria are limitations to exploit biogas production from fat-rich wastewaters. Generally reactors fail due to excessive LCFA accumulation onto the sludge. Here, long-term acclimation and bioaugmentation with a LCFA-degrading coculture were hypothesized as strategies to enhance methanogenic conversion of these compounds. Anaerobic sludges previously exposed to LCFA for more than 100 days converted a specific biomass-associated substrate of (3.2 ± 0.1) kg·kg−1 with very short lag phases (<1 day), whereas non-acclimated sludges showed lag phases of 11–15 days for metabolizing (1.6–1.8) kg·kg−1. Addition of a coculture of Syntrophomonas zehnderi and Methanobacterium formicicum to sludges previously loaded with LCFA and containing different amounts of biomass-associated substrate (from (0.5–3.2) kg·kg−1) did not improve methane production neither lag phases were shortened, indicating that the endogenous microbiota are not a limiting factor. Clearly, we show that long-term sludge acclimation to LCFA is essential for high rate methanogenesis from LCFA.The authors acknowledge the financial support by the European Regional Development Fund - ERDF, through the Operational Program Thematic Factors of Competitiveness - COMPETE, and by Portuguese funds, through the Portuguese Foundation for Science and Technology (FCT), in the frame of the project FCOMP-01-0124-FEDER-014784. FCT Strategic Project PEst-OE/EQB/LA0023/2013 is also acknowledged. A.J. Cavaleiro thanks FCT for the post-doctoral fellowship ref. SFRH/BPD/75247/2010. A.J.M. Stams has received funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. [323009]

    Long term outdoor operation of a tubular airlift pilot photobioreactor and a high rate algal pond as tertiary treatment of urban wastewater.

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    530 L high rate alga pond (HRAP) and 380 L airlift tubular photobioreactor (TPBR) were operated and compared in a urban wastewater treatment plant (WWTP), with the main purpose of removing nitrogen and phosphorous from the effluent of the WWTP while generating a valuable biomass. The photosynthetic activity in TPBR was during entire experiment higher than HRAP. The maximum areal productivity reached was 8.26 ± 1.43 and 21.76 ± 0.3 g SS m−2 d−1 for HRAP and TPBR respectively. Total nitrogen (TN) removal averaged 89.68 ± 3.12 and 65.12 ± 2.87% for TPBR and HRAP respectively, while for total phosphorus (TP) TPBR and HRAP averaged 86.71 ± 0.61 and 58.78 ± 1.17% respectively. The lipid content showed no significant differences (p < 0.05) between HRAP and TPBR averaging 20.80 ± 0.22 wt%. The main operating disadvantage of TPBR versus HRAP was the sever biofouling which forced to stop the experiment. Under the same conditions of operation TPBR was more limited at low temperatures than HRAP, and HRAP was more light limited than TPBR

    Calibration of a complex activated sludge model for the full-scale wastewater treatment plant

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    In this study, the results of the calibration of the complex activated sludge model implemented in BioWin software for the full-scale wastewater treatment plant are presented. Within the calibration of the model, sensitivity analysis of its parameters and the fractions of carbonaceous substrate were performed. In the steady-state and dynamic calibrations, a successful agreement between the measured and simulated values of the output variables was achieved. Sensitivity analysis revealed that upon the calculations of normalized sensitivity coefficient (Si,j) 17 (steady-state) or 19 (dynamic conditions) kinetic and stoichiometric parameters are sensitive. Most of them are associated with growth and decay of ordinary heterotrophic organisms and phosphorus accumulating organisms. The rankings of ten most sensitive parameters established on the basis of the calculations of the mean square sensitivity measure (ÎŽjmsqr) indicate that irrespective of the fact, whether the steady-state or dynamic calibration was performed, there is an agreement in the sensitivity of parameters
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