1,720,985 research outputs found
A chemical-biological integrated approach for the valorization of olive mill wastewaters
No full textAn integrated chemical-biological process for the recovery of natural phenolic compounds from an olive mill wastewater (OMW) and for the anaerobic production of volatile fatty acids (VFAs) from the pre-treated OMW was developed in this work. The recovery of OMW polyphenols was carried out through solid phase extraction (SPE) by
using Amberlite XAD16 resin as the adsorbent and ethanol as the biocompatible desorbing phase. Thereafter, the acidogenic digestion of the dephenolized OMW was performed in a mesophilic packed-bed biofilm reactor filled with ceramic cubes, who was operated at an OLR of about 5.9 g L-1 day-1. As a result of the integrated process, more than 60% of polyphenols were recovered and 19 gCOD L-1 of VFAs were obtained, representing more than 70% of the anaerobic effluent COD
Feed frequency in a Sequencing Batch Reactor strongly affects the production of polyhydroxyalkanoates (PHAs) from volatile fatty acids
No full textThe production of polyhydroxyalkanoates (PHAs) by activated sludge selected in a sequencing batch reactor (SBR) has been investigated. Several SBR runs were performed at the same applied organic load rate (OLR), hydraulic retention time (HRT) and feed concentration (8.5gCODL-1 of volatile fatty acids, VFAs) under aerobic conditions. The effect of the feeding time was only evaluated with a cycle length of 8h; for this particular cycle length, an increase in the storage response was observed by increasing the rate at which the substrate was fed into the reactor (at a fixed feeding frequency). Furthermore, a significantly stronger effect was observed by decreasing the cycle length from 8h to 6h and then to 2h, changing the feed frequency or changing the organic load given per cycle (all of the other conditions remained the same): the length of the feast phase decreased from 26 to 20.0 and then to 19.7% of the overall cycle length, respectively, due to an increase in the substrate removal rate. This removal rate was high and similar for the runs with cycle lengths of 2h and 6h in the SBR. This result was due to an increase in the selective pressure and the specific storage properties of the selected biomass. The highest polymer productivity after long-term accumulation batch tests was 1.7gPHAL-1d-1, with PHA content in the biomass of approximately 50% on a COD basis under nitrogen limitation. The DGGE profiles showed that the good storage performance correlated to the development of Lampropedia hyalina, which was only observed in the SBR runs characterized by a shorter cycle length. © 2013 Elsevier B.V
Repeated batch approach as a feasible procedure for the acclimatization of anaerobic consortia capable of an effective biomethanization of mechanically-sorted organic fraction of municipal solid waste
No full textThe acclimatization of anaerobic consortia capable of an effective biomethanization of a mechanically sorted-organic fraction of municipal solid waste (MS-OFMSW) was achieved in this study by following a repeated batch co-digestion approach. Mixtures of MS-OFMSW and cattle manure were processed in successive batch anaerobic digestion processes. Such an approach generally allowed a significantly increasing of the methane production when the MS-OFMSW represented the 30 and 40 % (v/v) of the initial mixture. On the other hand, the acclimated inocula did not adapt efficiently to higher concentration of the target waste MS-OFMSW. The acclimatization of the anaerobic consortia was demonstrated by means of molecular biology tools, by which a high diversity among populations occurring in the experimental matrices and after anaerobic processes was observed
Obtainment of a microbial consortium able to perform an effective biomethanization of a mechanically-sorted Organic fraction of municipal solid waste through a semicontinuous culture enrichment procedure
No full textMethane production yields achieved through the anaerobic digestion of mechanically sorted-organic fractions of municipal solid waste (MS-OFMSW) are generally lower than those obtained with source sorted-fractions (Hartmann and Ahring, 2006), but MS-OFMSW biomethanization can be enhanced through the acclimatization of a microbial population.
An anaerobic consortium capable of efficiently converting the organic fraction of MS-OFMSW into methane was obtained through a dedicated enrichment procedure in a 0.36 L up-flow anaerobic recirculated reactor. The system was initially filled with cattle manure (2.2% VSS, 6.2 g L-1 COD), an effective co-substrate for biomethanization of MS-OFMSW (Bertin et al., 2008); after a short batch working period, it was fed with MS-OFMSW according to a semi-continuous scheme, i.e. through successive short-time batch processes. In particular, at the beginning of each 56 hours batch cycle, 11mL of the processed waste were collected from the reactor, an equal volume of the waste (2.1% w/w VSS, 57.5 g L-1 COD) was then added by replacing part of the manure with MS-OFMSW which after 5 months theoretically constituted more than 99% of the reaction volume. The COD measured at the end of each period slowly decreased from 7.1 to 4.4 g L-1 and more than 90% of the overall COD fed during the experiment was depleted. Methanogenesis yield gradually increased up to 0.35 L g-1 depleted COD throughout the process. Molecular analysis of the microbial consortium indicated that while Archeal population was unaffected by sequencing fed-batch enrichment on MS-OFMSW, several hydrolytic and acidogenic Firmicutes and Bacteroidetes were enriched concomitantly to the observed increase of the biomethanization. The abovementioned bacterial species are probably essential for the effective biomethanization of MS-OFMSW carried out by the acclimated microbial community obtained in this study.
Hartmann H. and Ahring B.K. (2006). Wat. Sci. Technol. 53(8):7-22.
Bertin et al. (2008). Wat. Sci. Technol. 58(9):1735-174
Acclimation of an anaerobic consortium capable of an effective biomethanization of mechanically-sorted organic fraction of municipal solid waste through a semi-continuous enrichment procedure
No full textAneffective mesophilic continuous anaerobic digestion process fed only with amechanically sorted organic fraction of municipal solid waste (MS-OFMSW) was developed. During a preliminary 3-month experimental phase, the microbial consortium was acclimated
toward MS-OFMSW by initially filling the reactor with cattle manure and then continuously feeding it with MS-OFMSW. The Hydraulic Retention Time (HRT) and Organic Loading Rate (OLR) were 23 days and 2.5 g/L/day, respectively. After 4 weeks, the reactor reached stationary performances (84% COD removal yield, 0.15 LCH4 /gCODremoved methane production yield). The acclimated consortiumwasthen employed in a second run in which the reactorwasoperated under steady state conditions at the previous HRT and OLR for 73 days. The COD removal and the methane production yield increased up to 87% and 0.25 LCH4 /gCODremoved, respectively. The capability of the acclimated consortium to biomethanize MS-OFMSW was further studied via batch digestion experiments, carried out by inoculating the target waste with reactor effluents collected at the beginning of first run and at the end of the first and second run. The best normalized methane production (0.39 LCH4 /ginitial COD) was obtained with the inoculum collected at the end of the second run. Molecular analysis of the microbial community occurring in the reactor during the two sequential runs indicated that the progressive improvement of the process performances was closely related to the selection
and enrichment of specific hydrolytic and acidogenic bacteria in the reactor
A physicochemical-biotechnological approach for an integrated valorization of olive mill wastewater
No full textAn integrated physicochemical–biotechnological approach for a multipurpose valorization of olive mill wastewaters was studied. More than 60% of the wastewater natural polyphenols were recovered through a solid phase extraction procedure, by employing Amberlite XAD16 resin as the adsorbent and ethanol as the biocompatible desorbing phase. Thereafter, the dephenolized effluent was fed to a mesophilic anaerobic acidogenic packed-bed biofilm reactor for the bioconversion of the organic leftover into volatile fatty acids (VFAs). A VFAs concentration of 19 gCOD L1 was obtained, representing more than 70% of the COD occurring in the anaerobic effluent. The biotechnological process was assessed by means of bio-molecular analyses, which showed that the reactor packed bed was mostly colonized by bacteria of the Firmicutes phylogenetic group. The biorefinery scheme developed in this study allowed the obtainment of 1.59 g of
polyphenols per liter of wastewater treated and 2.72 gCOD L1 day1 of VFAs
Sludge minimization in municipal wastewater treatment by polyhydroxyalkanoate (PHA) production
No full textAn innovative approach has been recently pro- posed in order to link polyhydroxyalkanoates (PHA) produc- tion with sludge minimization in municipal wastewater treat- ment, where (1) a sequencing batch reactor (SBR) is used for the simultaneous municipal wastewater treatment and the selection/enrichment of biomass with storage ability and (2) the acidogenic fermentation of the primary sludge is used to produce a stream rich in volatile fatty acids (VFAs) as the carbon source for the following PHA accumulation stage. The reliability of the proposed process has been evaluated at lab scale by using substrate synthetic mixtures for both stages, simulating a low-strength municipal wastewater and the efflu- ent from primary sludge fermentation, respectively. Six SBR runs were performed under the same operating conditions, each time starting from a new activated sludge inoculum. In every SBR run, despite the low VFA content (10% chemical oxygen demand, COD basis) of the substrate synthetic mix- ture, a stable feast–famine regime was established, ensuring the necessary selection/enrichment of the sludge and soluble COD removal to 89 %. A good process reproducibility was observed, as also confirmed by denaturing gradient gel elec- trophoresis (DGGE) analysis of the microbial community, which showed that a high similarity after SBR steady-state had been reached. The main variation factors of the storage properties among different runs were uncontrolled changes of settling properties which in turn caused variations of both sludge retention time and specific organic loading rate. In the following accumulation batch tests, the selected/enriched consortium was able to accumulate PHA with good rate (63 mg CODPHA g CODXa−1h−1) and yield (0.23 CODPHA CODΔS−1) in spite that the feeding solution was different from the acclimation one. Even though the PHA production perfor- mance still requires optimization, the proposed process has a good potential especially if coupled to minimization of both primary sludge (by its use as the VFA source for the PHA accumulation, via previous fermentation) and excess second- ary sludge (by its use as the biomass source for the PHA accumulation)
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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