JoVE Visualize What is visualize?
Stop Reading. Start Watching.
Advanced Search
Stop Reading. Start Watching.
Regular Search
Find video protocols related to scientific articles indexed in Pubmed.
Biohydrogen, biomethane and bioelectricity as crucial components of biorefinery of organic wastes: a review.
Waste Manag Res
PUBLISHED: 04-17-2014
Show Abstract
Hide Abstract
Biohydrogen is a sustainable form of energy as it can be produced from organic waste through fermentation processes involving dark fermentation and photofermentation. Very often biohydrogen is included as a part of biorefinery approaches, which reclaim organic wastes that are abundant sources of renewable and low cost substrate that can be efficiently fermented by microorganisms. The aim of this work was to critically assess selected bioenergy alternatives from organic solid waste, such as biohydrogen and bioelectricity, to evaluate their relative advantages and disadvantages in the context of biorefineries, and ?nally to indicate the trends for future research and development. Biorefining is the sustainable processing of biomass into a spectrum of marketable products, which means: energy, materials, chemicals, food and feed. Dark fermentation of organic wastes could be the beach-head of complete biorefineries that generate biohydrogen as a first step and could significantly influence the future of solid waste management. Series systems show a better efficiency than one-stage process regarding substrate conversion to hydrogen and bioenergy. The dark fermentation also produces fermented by-products (fatty acids and solvents), so there is an opportunity for further combining with other processes that yield more bioenergy. Photoheterotrophic fermentation is one of them: photosynthetic heterotrophs, such as non-sulfur purple bacteria, can thrive on the simple organic substances produced in dark fermentation and light, to give more H2. Effluents from photoheterotrophic fermentation and digestates can be processed in microbial fuel cells for bioelectricity production and methanogenic digestion for methane generation, thus integrating a diverse block of bioenergies. Several digestates from bioenergies could be used for bioproducts generation, such as cellulolytic enzymes and saccharification processes, leading to ethanol fermentation (another bioenergy), thus completing the inverse cascade. Finally, biohydrogen, biomethane and bioelectricity could contribute to significant improvements for solid organic waste management in agricultural regions, as well as in urban areas.
Related JoVE Video
Emulsifying activity and stability of a non-toxic bioemulsifier synthesized by Microbacterium sp. MC3B-10.
Int J Mol Sci
PUBLISHED: 08-20-2013
Show Abstract
Hide Abstract
A previously reported bacterial bioemulsifier, here termed microbactan, was further analyzed to characterize its lipid component, molecular weight, ionic character and toxicity, along with its bioemulsifying potential for hydrophobic substrates at a range of temperatures, salinities and pH values. Analyses showed that microbactan is a high molecular weight (700 kDa), non-ionic molecule. Gas chromatography of the lipid fraction revealed the presence of palmitic, stearic, and oleic acids; thus microbactan may be considered a glycolipoprotein. Microbactan emulsified aromatic hydrocarbons and oils to various extents; the highest emulsification index was recorded against motor oil (96%). The stability of the microbactan-motor oil emulsion model reached its highest level (94%) at 50 °C, pH 10 and 3.5% NaCl content. It was not toxic to Artemia salina nauplii. Microbactan is, therefore, a non-toxic and non-ionic bioemulsifier of high molecular weight with affinity for a range of oily substrates. Comparative phylogenetic assessment of the 16S rDNA gene of Microbacterium sp. MC3B-10 with genes derived from other marine Microbacterium species suggested that this genus is well represented in coastal zones. The chemical nature and stability of the bioemulsifier suggest its potential application in bioremediation of marine environments and in cosmetics.
Related JoVE Video
The influence of total solids content and initial pH on batch biohydrogen production by solid substrate fermentation of agroindustrial wastes.
J. Environ. Manage.
PUBLISHED: 04-04-2013
Show Abstract
Hide Abstract
Hydrogen is a valuable clean energy source, and its production by biological processes is attractive and environmentally sound and friendly. In México 5 million tons/yr of agroindustrial wastes are generated; these residues are rich in fermentable organic matter that can be used for hydrogen production. On the other hand, batch, intermittently vented, solid substrate fermentation of organic waste has attracted interest in the last 10 years. Thus the objective of our work was to determine the effect of initial total solids content and initial pH on H2 production in batch fermentation of a substrate that consisted of a mixture of sugarcane bagasse, pineapple peelings, and waste activated sludge. The experiment was a response surface based on 2(2) factorial with central and axial points with initial TS (15-35%) and initial pH (6.5-7.5) as factors. Fermentation was carried out at 35 °C, with intermittent venting of minireactors and periodic flushing with inert N2 gas. Up to 5 cycles of H2 production were observed; the best treatment in our work showed cumulative H2 productions (ca. 3 mmol H2/gds) with 18% and 6.65 initial TS and pH, respectively. There was a significant effect of TS on production of hydrogen, the latter decreased with initial TS increase from 18% onwards. Cumulative H2 productions achieved in this work were higher than those reported for organic fraction of municipal solid waste (OFMSW) and mixtures of OFMSW and fruit peels waste from fruit juice industry, using the same process. Specific energetic potential due to H2 in our work was attractive and fell in the high side of the range of reported results in the open literature. Batch dark fermentation of agrowastes as practiced in our work could be useful for future biorefineries that generate biohydrogen as a first step and could influence the management of this type of agricultural wastes in México and other countries and regions as well.
Related JoVE Video
Enzymes involved in the biodegradation of hexachlorocyclohexane: a mini review.
J. Environ. Manage.
PUBLISHED: 06-19-2011
Show Abstract
Hide Abstract
The scope of this paper encompasses the following subjects: (i) aerobic and anaerobic degradation pathways of ?-hexachlorocyclohexane (HCH); (ii) important genes and enzymes involved in the metabolic pathways of ?-HCH degradation; (iii) the instrumental methods for identifying and quantifying intermediate metabolites, such as gas chromatography coupled to mass spectrometry (GC-MS) and other techniques. It can be concluded that typical anaerobic and aerobic pathways of ?-HCH are well known for a few selected microbial strains, although less is known for anaerobic consortia where the possibility of synergism, antagonism, and mutualism can lead to more particular routes and more effective degradation of ?-HCH. Conversion and removals in the range 39%-100% and 47%-100% have been reported for aerobic and anaerobic cultures, respectively. Most common metabolites reported for aerobic degradation of lindane are ?-pentachlorocyclohexene (?-PCCH), 2,5-dichlorobenzoquinone (DCBQ), Chlorohydroquinone (CHQ), chlorophenol, and phenol, whereas PCCH, isomers of trichlorobenzene (TCB), chlorobenzene, and benzene are the most typical metabolites found in anaerobic pathways. Enzyme and genetic characterization of the involved molecular mechanisms are in their early infancy; more work is needed to elucidate them in the future. Advances have been made on identification of enzymes of Sphingomonas paucimobilis where the gene LinB codifies for the enzyme haloalkane dehalogenase that acts on 1,3,4,6-tetrachloro 1,4-cyclohexadiene, thus debottlenecking the pathway. Other more common enzymes such as phenol hydroxylase, catechol 1,2-dioxygenase, catechol 2,3-dioxygenase are also involved since they attack intermediate metabolites of lindane such as catechol and less substituted chlorophenols. Chromatography coupled to mass spectrometric detector, especially GC-MS, is the most used technique for resolving for ?-HCH metabolites, although there is an increased participation of HPLC-MS methods. Scintillation methods are very useful to assess final degradation of ?-HCH.
Related JoVE Video
Re-fermentation of washed spent solids from batch hydrogenogenic fermentation for additional production of biohydrogen from the organic fraction of municipal solid waste.
J. Environ. Manage.
PUBLISHED: 01-18-2011
Show Abstract
Hide Abstract
In the first batch solid substrate anaerobic hydrogenogenic fermentation with intermittent venting (SSAHF-IV) of the organic fraction of municipal solid waste (OFMSW), a cumulative production of 16.6 mmol H(2)/reactor was obtained. Releases of hydrogen partial pressure first by intermittent venting and afterward by flushing headspace of reactors with inert gas N(2) allowed for further hydrogen production in a second to fourth incubation cycle, with no new inoculum nor substrate nor inhibitor added. After the fourth cycle, no more H(2) could be harvested. Interestingly, accumulated hydrogen in 4 cycles was 100% higher than that produced in the first cycle alone. At the end of incubation, partial pressure of H(2) was near zero whereas high concentrations of organic acids and solvents remained in the spent solids. So, since approximate mass balances indicated that there was still a moderate amount of biodegradable matter in the spent solids we hypothesized that the organic metabolites imposed some kind of inhibition on further fermentation of digestates. Spent solids were washed to eliminate organic metabolites and they were used in a second SSAHF-IV. Two more cycles of H(2) production were obtained, with a cumulative production of ca. 2.4 mmol H(2)/mini-reactor. As a conclusion, washing of spent solids of a previous SSAHF-IV allowed for an increase of hydrogen production by 15% in a second run of SSAHF-IV, leading to the validation of our hypothesis.
Related JoVE Video
Design of a new rotating drum bioreactor operated at atmospheric pressure on the bioremediation of a polluted soil.
Bioprocess Biosyst Eng
PUBLISHED: 05-13-2009
Show Abstract
Hide Abstract
This paper reports the effect of the operation and design characteristics of rotating drum bioreactors (RDBs) aerated by natural convection and applied to the treatment of a soil highly polluted with weathered total petroleum hydrocarbons (TPH) (55,000 +/- 2,600 mg/kg). The parameters studied were length to diameter ratio (L/D), rotating speed (N) and lifter type. The highest TPH removal (59.6 +/- 0.7%) was obtained with the RDB of the lowest L/D ratio (1.5). Removals diminished by 27, 36 and 56%, with a ratio increment of 2.1, 3.1 and 5.1, respectively. Increment of the N, at an optimal value and lifter change from straight to helicoidal showed an improvement on the TPH removal of 20 and 30%, respectively. According to these results, slurry surface renewal through the variation of the N and the change of slurry flow was able to improve TPH removal in RDBs operated by natural convection.
Related JoVE Video
Anthracene decomposition in soils by conventional ozonation.
J. Environ. Manage.
Show Abstract
Hide Abstract
Anthracene decomposition in solid phase by conventional ozonation was investigated employing model and real soil samples. Reaction in a two-phase system (soil-ozone) and a three-phase system (soil-water-ozone) was studied. The total anthracene decomposition in the two studied systems (sand-ozone and burned soil-ozone) was obtained at 15 and 30 min of treatment by ozone, respectively, and the efficiency of ozonation was depended on the water content in treated soil samples. The anthracene degradation in an agricultural soil (free water) was carried up slower (only 30% after 90 min of ozonation), because the real solid samples content organic matter that provokes the additionally ozone consuming. The pre-ozonation of free anthracene agricultural soil depicts the content of the organic matter fraction, which have the ozone reactivity orders as aromatic>aliphatic>polar. In all cases, the ozonation by-products were identified partiality; the majority of by-products formatted react with ozone. Actually some of them were decomposed totally, while others were accumulated. Some products identified in all systems such as anthrone, 9,10-anthraquinone and phthalic acid, are less toxic than the anthracene.
Related JoVE Video
Influence of discontinuing feeding degradable cosubstrate on the performance of a fluidized bed bioreactor treating a mixture of trichlorophenol and phenol.
J. Environ. Manage.
Show Abstract
Hide Abstract
The purpose of our research was to evaluate the effect of eliminating supplementation of sucrose to the reactor influent on the performance of a lab scale partially-aerated methanogenic fluidized bed bioreactor (PAM-FBBR). Two operational stages were distinguished: in the first stage the influent contained a mixture of 120/30/1000 mg/L of 2,4,6-trichlorophenol/phenol/COD-sucrose (TCP/Phe/COD-sucrose); in the second stage only the xenobiotic concentrations were the same 120/30 mg/L of TCP/Phe whereas sucrose addition was discontinued. Removal efficiencies of TCP, Phe, and COD were very high and close for both stages; i.e., ?(TCP): 99.9 and 99.9%; ?(Phe): 99.9 and 99.9%; ?(COD) = 96.46 and 97.48% for stage 1 and stage 2, respectively. Traces of 2,4,6 dichlorophenol (0.05 mg/L) and 4-chlorophenol (0.07-0.26 mg/L) were found during the first 15 days of operation of the second stage, probably due to the adaptation to no co-substrate conditions. Net increase of chloride anion Cl(-) in effluent ranged between 59.5 and 61.5 mg Cl(-)/L that was very close to the maximum theoretical concentration of 62.8 mg Cl(-)/L. PCR-DGGE analysis revealed a richness decrease of eubacterial domain posterior to sucrose elimination from the influent whereas archaeal richness remained almost the same. However, the bioreactor performance was not negatively affected by discontinuing the addition of co-substrate sucrose. Our results indicate that the application of PAM-FBBR to the treatment of groundwaters polluted with chlorophenols and characterized by the lack of easily degradable co-substrates, is a promising alternative for on site bioremediation.
Related JoVE Video

What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.