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Natural wetland emissions of methylated trace elements
Vriens, B. ; Lenz, M. ; Charlet, L. ; Berg, M. ; Winkel, L.H.E. - \ 2014
Nature Communications 5 (2014). - ISSN 2041-1723
yellowstone-national-park - selenium volatilization - atmospheric selenium - biomethylation - soil - speciation - bacterium - products - sulfide - sulfur
Natural wetlands are well known for their significant methane emissions. However, trace element emissions via biomethylation and subsequent volatilization from pristine wetlands are virtually unstudied, even though wetlands constitute large reservoirs for trace elements. Here we show that the average volatile fluxes of selenium (
Bio-reduction of elemental sulfur to increase the gold recovery from enargite
Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2012
Hydrometallurgy 115 (2012). - ISSN 0304-386X - p. 93 - 97.
refractory ore - dissolution - oxidation - sulfide - ferrooxidans - concentrate - bacteria - kinetics - pyrite - zinc
The mineral enargite can be of interest to the mining industry as a copper and precious metal source. The mineral has a refractory character towards oxidation, which is attributed to the formation of elemental sulfur that seals off the mineral surface. In this study it was investigated whether elemental sulfur resulting from oxidation during industrial milling can be converted into hydrogen sulfide via bio-reduction. The removal of elemental sulfur in this process will clean the mineral surfaces for subsequent oxidation, prevent interference with the gold extraction process and reduce consumption of chemicals such as cyanide. HPLC analysis confirmed that indeed elemental sulfur was formed during industrial milling of an enargite-pyrite gold concentrate. Removal of elemental sulfur via bio-reduction was successful and improved the gold leachability from 48.9% to 69.6%. The combination of milling and bio-reduction was therefore concluded to be a possible route to liberate metals. Further research is necessary to investigate if the enargite to sulfur conversion can be improved to obtain economically satisfactory (> 90%) gold recoveries.
Molecular analysis of the biomass of a fluidized bed reactor treating synthetic vinasse at anaerobic and micro-aerobic conditions
Rodriguez, E. ; Lopes, A. ; Fdz-Polanco, M. ; Stams, A.J.M. ; Garcia Encina, P.A. - \ 2012
Applied Microbiology and Biotechnology 93 (2012)5. - ISSN 0175-7598 - p. 2181 - 2191.
sulfate-reducing bacteria - 16s ribosomal-rna - gradient gel-electrophoresis - waste-water - oxygen limitation - granular sludge - sp-nov. - sulfide - desulfovibrio - competition
The microbial communities (Bacteria and Archaea) established in an anaerobic fluidized bed reactor used to treat synthetic vinasse (betaine, glucose, acetate, propionate, and butyrate) were characterized by denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis. This study was focused on the competitive and syntrophic interactions between the different microbial groups at varying influent substrate to sulfate ratios of 8, 4, and 2 and anaerobic or micro-aerobic conditions. Acetogens detected along the anaerobic phases at substrate to sulfate ratios of 8 and 4 seemed to be mainly involved in the fermentation of glucose and betaine, but they were substituted by other sugar or betaine degraders after oxygen application. Typical fatty acid degraders that grow in syntrophy with methanogens were not detected during the entire reactor run. Likely, sugar and betaine degraders outnumbered them in the DGGE analysis. The detected sulfate-reducing bacteria (SRB) belonged to the hydrogen-utilizing Desulfovibrio. The introduction of oxygen led to the formation of elemental sulfur (S(0)) and probably other sulfur compounds by sulfide-oxidizing bacteria (¿-Proteobacteria). It is likely that the sulfur intermediates produced from sulfide oxidation were used by SRB and other microorganisms as electron acceptors, as was supported by the detection of the sulfur respiring Wolinella succinogenes. Within the Archaea population, members of Methanomethylovorans and Methanosaeta were detected throughout the entire reactor operation. Hydrogenotrophic methanogens mainly belonging to the genus Methanobacterium were detected at the highest substrate to sulfate ratio but rapidly disappeared by increasing the sulfate concentration
Volatile sulphur compounds in morning breath of human volunteers.
Snel, J. ; Burgering, M. ; Smit, B. ; Noordman, W. ; Tangerman, A. ; Winkel, E.G. ; Kleerebezem, M. - \ 2011
Archives of Oral Biology 56 (2011)1. - ISSN 0003-9969 - p. 29 - 34.
oral malodor - healthy-subjects - flow-rate - halitosis - gender - mouth - sulfide - saliva - whole - odor
OBJECTIVE: morning breath contains elevated concentrations of volatile sulphur components (VSCs). Therefore, morning breath is recognised as a surrogate target for interventions on breath quality. Nevertheless, factors influencing morning breath are poorly understood. Our aim was to evaluate concentrations of VSC at the time of awakening. METHODS: a procedure was developed to collect breath samples at home. Intra- and inter-person variations were determined in two small studies based on measurements of hydrogen sulphide, methyl mercaptan and dimethyl sulphide in healthy volunteers. RESULTS: highest levels of VSC were found directly after waking up, followed by a significant decline afterward. Considerable day-to-day variation was found, but could not be linked to dietary intake. A significantly higher concentration of H(2)S and CH(3)SH was observed in the group of female subjects compared to males. CONCLUSIONS: when morning breath is used as a target for interventions, breath collected at the time of or shortly after waking up is preferred over breath collected later during the morning. Gender plays an important role in VSC levels, and should be taken into account
Biological treatment of refinery spent caustics under halo-alkaline conditions
Graaff, M. de; Bijmans, M.F.M. ; Abbas, B. ; Euverink, G.J.W. ; Muyzer, G. ; Janssen, A.J.H. - \ 2011
Bioresource Technology 102 (2011)15. - ISSN 0960-8524 - p. 7257 - 7264.
sulfur-oxidizing bacteria - soda lake - sp-nov - oxidation processes - mono lake - gen. nov. - diversity - sulfide - water - bacteriochlorophyll
The present research demonstrates the biological treatment of refinery sulfidic spent caustics in a continuously fed system under halo-alkaline conditions (i.e. pH 9.5; Na(+)= 0.8M). Experiments were performed in identical gas-lift bioreactors operated under aerobic conditions (80-90% saturation) at 35°C. Sulfide loading rates up to 27 mmol L(-1)day(-1) were successfully applied at a HRT of 3.5 days. Sulfide was completely converted into sulfate by the haloalkaliphilic sulfide-oxidizing bacteria belonging to the genus Thioalkalivibrio. Influent benzene concentrations ranged from 100 to 600 µM. At steady state, benzene was removed by 93% due to high stripping efficiencies and biodegradation. Microbial community analysis revealed the presence of haloalkaliphilic heterotrophic bacteria belonging to the genera Marinobacter, Halomonas and Idiomarina which might have been involved in the observed benzene removal. The work shows the potential of halo-alkaliphilic bacteria in mitigating environmental problems caused by alkaline waste.
Hydrogenotrophic Sulfate Reduction in a Gas-Lift Bioreactor Operated at 9 degrees C
Nevatalo, L.M. ; Bijmans, M.F.M. ; Lens, P.N.L. ; Kaksonen, A.H. ; Puhakka, J.A. - \ 2010
Journal of Microbiology and Biotechnology 20 (2010)3. - ISSN 1017-7825 - p. 615 - 621.
reducing bacteria - retention time - carbon-dioxide - growth-rate - sp-nov - reactor - temperature - methanogenesis - oxidation - sulfide
The viability of low-temperature sulfate reduction with hydrogen as electron donor was studied with a bench-scale gas-lift bioreactor (GLB) operated at 9 degrees C. Prior to the GLB experiment, the temperature range of sulfate reduction of the inoculum was assayed. The results of the temperature gradient assay indicated that the inoculum was a psychrotolerant mesophilic enrichment culture that had an optimal temperature for sulfate reduction of 31 degrees C, and minimum and maximum temperatures of 7 degrees C and 41 degrees C, respectively. In the GLB experiment at 9 degrees C, a sulfate reduction rate of 500-600 mg l(-1) d(-1), corresponding to a specific activity of 173 mg SO42- g VSS-1 d(-1), was obtained. The electron flow from the consumed H-2-gas to sulfate reduction varied between 27% and 52%, whereas the electron flow to acetate production decreased steadily from 15% to 5%. No methane was produced. Acetate was produced from CO2 and H-2 by homoacetogenic bacteria. Acetate supported the growth of some heterotrophic sulfate-reducing bacteria. The sulfate reduction rate in the GLB was limited by the slow biomass growth rate at 9 degrees C and low biomass retention in the reactor. Nevertheless, this study demonstrated the potential sulfate reduction rate of psychrotolerant sulfate-reducing mesophiles at suboptimal temperature.
Sulfate Reduction at pH 4.0 for Treatment of Process and Wastewaters
Bijmans, M.F.M. ; Vries, E. de; Yang, C.H. ; Buisman, C.J.N. ; Lens, P.N.L. ; Dopson, M. - \ 2010
Biotechnology Progress 26 (2010)4. - ISSN 8756-7938 - p. 1029 - 1037.
acid-mine drainage - gradient gel-electrophoresis - reducing bacteria - anaerobic reactor - bioreactor - hydrogen - sulfide - growth - water - removal
Acidic industrial process and wastewaters often contain high sulfate and metal concentrations and their direct biological treatment is thus far not possible as biological processes at pH <5 have been neglected. Sulfate-reducing bacteria convert sulfate to sulfide that can subsequently be used to recover metals as metal-sulfides precipitate. This study reports on high-rate sulfate reduction with a mixed microbial community at pH 4.0 and 4.5 with hydrogen and/or formate as electron donors. The maximum sulfate reducing activity at pH 4.0 was sustained for over 40 days with a specific activity 500-fold greater than previously reported values: 151 mmol sulfate reduced/L reactor liquid per day with a maximum specific activity of 84 mmol sulfate per gram of volatile suspended solids per day. The biomass yield gradually decreased from 38 to 0.4 g volatile suspended solids per kilogram of sulfate when decreasing the reactor pH from pH 6 to 4. The microorganisms had a high maintenance requirement probably due maintaining pH homeostasis and the toxicity of sulfide at low pH. The microbial community diversity in the pH 4.0 membrane bioreactor decreased over time, while the diversity of the sulfate reducing community increased. Thus, a specialized microbial community containing a lower proportion of microorganisms capable of activity at pH 4 developed in the reactor compared with those present at the start of the experiment. The 16S rRNA genes identified from the pH 4.0 grown mixed culture were most similar to those of Desulfovibrio species and Desulfosporosinus sp. M1. (C) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 26: 1029-1037, 2010
Alternative Stable States Driven by Density-Dependent Toxicity
Heide, T. van der; Nes, E.H. van; Katwijk, M.M. van; Scheffer, M. ; Hendriks, A.J. ; Smolders, A.J.P. - \ 2010
Ecosystems 13 (2010)6. - ISSN 1432-9840 - p. 841 - 850.
eelgrass zostera-marina - distinguishing resource competition - fresh-water wetlands - vegetation dieback - baltic sea - ecosystems - sulfide - phytotoxicity - interference - populations
Many populations are exposed to naturally occurring or synthetic toxicants. An increasing number of studies demonstrate that the toxicity of such compounds is not only dependent on the concentration or load, but also on the biomass or density of exposed organisms. At high biomass, organisms may be able to alleviate adverse effects of the toxicant by actively lowering ambient concentrations through either a joint detoxification mechanism or growth dilution. We show in a conceptual model that this mechanism may potentially lead to alternative stable states if the toxicant is lethal at low densities of organisms, whereas a high density is able to reduce the toxicant concentrations to sub-lethal levels. We show in an example that this effect may be relevant in real ecosystems. In an earlier published experimental laboratory study, we demonstrated that ammonia toxicity in eelgrass is highly dependent on the eelgrass shoot density. Here, we used the results of these experiments to construct a model describing the complex interactions between the temperate seagrass Zostera marina and potentially lethal ammonia. Analyses of the model show that alternative stable states are indeed present over wide ranges of key-parameter settings, suggesting that the mechanism might be important especially in sheltered, eutrophicated estuaries where mixing of the water layer is poor. We argue that the same mechanism could cause alternative stable states in other biological systems as well.
The effect of sub-optimal temperature on specific sulfidogenic activity of mesophilic SRB in an H-2-fed membrane bioreactor
Nevatalo, L.M. ; Bijmans, M.F.M. ; Lens, P.N.L. ; Kaksonen, A.H. ; Puhakka, J.A. - \ 2010
Process Biochemistry 45 (2010)3. - ISSN 1359-5113 - p. 363 - 368.
gas-lift reactor - sulfate reduction - waste-water - retention time - carbon source - metal - bacteria - hydrogen - sulfide - growth
The sulfidogenic activity of two mesophilic sulfate reducing enrichment cultures was studied in H-2-fed membrane bioreactors. The two enrichment cultures had different origins; one of them was a mesophilic and the other a psychrotolerant mesophilic culture. The operational temperatures of the reactors were gradually changed: for one the temperature was increased from 9 to 30 degrees C and for the other it was decreased from 35 to 9 degrees C. The specific sulfidogenic activities were 21-31, 52-53 and 57-92 mmol SO42- g VSS-1 d(-1) at 9, 15 and 30-35 degrees C, respectively. The sulfate reduction rate of the SRB stabilized to a lower level after the temperature was decreased. The percent electron flow to sulfate reduction was on average 24-32, 50 and 47-69% at 9, 15 and 30-35 degrees C, respectively. The capability of mesophilic SRB to oxidize electron donor decreased as the temperature was decreased. The results indicate that starting of the reactor operation at 9 degrees C resulted in higher sulfidogenic activity at suboptimal temperatures and selective enrichment of the psychrotolerant species improved. The start-up of the reactor at 35 degrees C resulted in decreased sulfidogenic activity as the temperature was decreased. This indicates that the operational temperature of bioreactors with mesophilic SRB can be decreased to 15-20 degrees C and the sulfidogenic activity will decrease by 10-40%. Moreover, an operational temperature of 9 degrees C seems to be close to the lower limit of active sulfate reduction for the mesophilic enrichment cultures used in this study.
Terrestrial gross carbon dioxide uptake: Global distribution and covariation with climate
Beer, C. ; Veenendaal, E.M. - \ 2010
Science 329 (2010)5993. - ISSN 0036-8075 - p. 834 - 838.
atmospheric co2 - vegetation - biosphere - ecosystems - radiation - products - fraction - database - sulfide - network
Terrestrial gross primary production (GPP) is the largest global CO2 flux driving several ecosystem functions. We provide an observation-based estimate of this flux at 123 ± 8 petagrams of carbon per year (Pg C year-1) using eddy covariance flux data and various diagnostic models. Tropical forests and savannahs account for 60%. GPP over 40% of the vegetated land is associated with precipitation. State-of-the-art process-oriented biosphere models used for climate predictions exhibit a large between-model variation of GPP’s latitudinal patterns and show higher spatial correlations between GPP and precipitation, suggesting the existence of missing processes or feedback mechanisms which attenuate the vegetation response to climate. Our estimates of spatially distributed GPP and its covariation with climate can help improve coupled climate–carbon cycle process models.
Monitoring ZnS Precipitation: Estimation, Error Analysis and Experiment Design
Sampaio, R.M. ; Keesman, K.J. ; Lens, P.N.L. - \ 2009
Separation Science and Technology 44 (2009)8. - ISSN 0149-6395 - p. 1675 - 1703.
A mass balance model of total soluble sulfide and free zinc with a second-order reaction term is theoretically able to reconstruct the zinc effluent concentration and the kinetic parameter (k). However, under real conditions this model predicts the zinc effluent concentration four orders of magnitude higher than the measured ones. The applied error analysis, based on linearization of the model followed by first-order variance propagation, showed that the accuracy of several of the input variables (flows and influent concentrations) jeopardized the estimation of the Zn concentration in the effluent, which is a phenomenon expected for every fast reaction with low product concentration. In order to overcome the inaccuracy issue, an ¿apparent solubility product¿ as a function of pS (11-2011, 12, 13, 14, 15, 16, 17, 18, 19, 20) was calculated from the experimental data, allowing for the subsequent determination of an ¿apparent kinetic parameter¿ (kA), that excluding parallel reactions was between 1.7 1023 - 6.2 1024 L/(mol·h). This allowed for further tuning of the model such that the estimates of the Zn effluent concentration became of the same order of magnitude as the measured ones (10-7 M Zn)
Anaerobic methanethiol degradation in upflow anaerobic sludge bed reactors at high salinity (> 0.5 M Na+)
Leerdam, R.C. van; Bok, F.A.M. de; Lens, P.N.L. ; Stams, A.J.M. ; Janssen, A.J.H. - \ 2007
Biotechnology and Bioengineering 98 (2007)1. - ISSN 0006-3592 - p. 91 - 100.
mill waste-water - sulfur-compounds - methylotrophic methanogen - estuarine methanogen - blanket reactor - sp-nov - sediments - sulfide - sulfate - adaptation
The feasibility of anaerobic methanethiol (MT) degradation at elevated sodium concentrations was investigated in a mesophilic (30°C) lab-scale upflow anaerobic sludge bed (UASB) reactor, inoculated with estuarine sediment originating from the Wadden Sea (The Netherlands). MT was almost completely degraded (>95%) to sulfide, methane and carbon dioxide at volumetric loading rates up to 37 mmol MT·L-1·day-1, 0.5 M sodium (NaCl or NaHCO3) and between pH 7.3 and 8.4. Batch experiments revealed that inhibition of MT degradation started at sodium (both NaCl and NaHCO3) concentrations exceeding 0.8 M. Sulfide inhibited MT degradation already around 3 mM (pH 8.3).
Effect of sulfate and iron on physico-chemical characteristics of anaerobic granular sludge
Hullebusch, E.D. van; Gieteling, J. ; Daele, W. van; Defrancq, J. ; Lens, P.N.L. - \ 2007
Biochemical Engineering Journal 33 (2007)2. - ISSN 1369-703X - p. 168 - 177.
extracellular polymeric substances - waste-water - viscosity evolution - reducing bacteria - blanket reactors - egsb reactors - uasb - precipitation - sulfide - localization
This research investigated the effect of the substrate composition (no substrate, glucose, glucose + sulfate or glucose + sulfate + iron) on the physico-chemical characteristics of two different anaerobic granular sludges as a function of time. The sludges were fed batch wise (pH 7, 30 °C) at an organic loading rate of 1.2 g COD l¿1 d¿1 (0.04 g COD g VSS¿1 day¿1) for 30 days. The presence of sulfate (COD/sulfate ratio = 1) in the feed of glucose fed anaerobic sludges did not change the physico-chemical characteristics throughout the incubation. In contrast, the presence of iron in the feed (in addition to glucose and sulfate, COD/iron ratio = 1) reduced the protein and carbohydrate content in the SMP and EPS with about 50% after 30 days incubation compared to the other feeding conditions. The sludge grown on glucose + sulfate + iron contained much more iron (+300¿500%) and sulfur (+200¿350%) than the other incubated sludges both after 14 and 30 days. The higher mineral content (lower VSS content) and the decrease of the EPS content contributed to the disintegration of iron fed granules, as shown by their lower size particles. However, the iron fed sludge displayed a higher granule strength than the other incubated sludges. Although an appreciable variation in the granule strength was noticed between the sludges investigated, it was not possible to relate these differences to their inorganic composition, the chemical composition of the extracted polymers or to the physical characteristics investigated
Effect of sulfur compounds on biological reduction of nitric oxide in aqueous Fe(II)EDTA2- solutions
Manconi, I. ; Maas, P.M.F. van der; Lens, P.N.L. - \ 2006
Nitric oxide : biology and chemistry 15 (2006)1. - ISSN 1089-8603 - p. 40 - 49.
denitrifying pseudomonas-fluorescens - nitrous-oxide - waste-water - flue-gases - sulfide - denitrification - removal - inhibition - respiration - bioreactors
Biological reduction of nitric oxide (NO) in aqueous solutions of EDTA chelated Fe(II) is one of the main steps in the BioDeNOx process, a novel bioprocess for the removal of nitrogen oxides (NOx) from polluted gas streams. Since NOx contaminated gases usually also contain sulfurous pollutants, the possible interferences of these sulfur compounds with the BioDeNOx process need to be identified. Therefore, the effect of the sulfur compounds Na2SO4, Na2SO3, and H2S on the biological NO reduction in aqueous solutions of Fe(II)EDTA2¿ (25 mM, pH 7.2, 55 °C) was studied in batch experiments. Sulfate and sulfite were found to not affect the reduction rate of Fe(II)EDTA2¿ complexed NO under the conditions tested. Sulfide, either dosed externally or formed during the batch incubation out of endogenous sulfur sources or the supplied sulfate or sulfite, influences the production and consumption of the intermediate nitrous oxide (N2O) during Fe(II)EDTA2¿ bound NO reduction. At low concentrations (0.2 g VSS/l) of denitrifying sludge, 0.2 mM free sulfide completely inhibited the nitrosyl-complex reduction. At higher biomass concentrations (1.3¿2.3 g VSS/l), sulfide (from 15 ¿M to 0.8 mM) induced an incomplete NO denitrification with N2O accumulation. The reduction rates of NO to N2O were enhanced by anaerobic sludge, presumably because it kept FeEDTA in the reduced state
Cobalt sorption onto anaerobic granular sludge: Isotherm and spatial localization analysis
Hullebusch, E.D. van; Gieteling, J. ; Zhang, M. ; Zandvoort, M.H. ; Daele, W. van; Defrancq, J. ; Lens, P.N.L. - \ 2006
Journal of Biotechnology 121 (2006)2. - ISSN 0168-1656 - p. 227 - 240.
extracellular polymeric substances - sequential extraction procedure - soluble microbial products - heavy-metals - methanol degradation - activated-sludge - uasb reactors - nickel - sulfide - eps
This study investigated the effect of different feeding regimes on the cobalt sorption capacity of anaerobic granular sludge from a full-scale bioreactor treating paper mill wastewater. Adsorption experiments were done with non-fed granules in monometal (only Co) and competitive conditions (Co and Ni in equimolar concentrations). In order to modify the extracellular polymeric substances and sulfides content of the granules, the sludge was fed for 30 days with glucose (pH 7, 30 °C, organic loading rate = 1.2 g glucose l¿1 day¿1) in the presence (COD/SO42¿ = 1) or absence of sulfate. The partitioning of the sorbed cobalt between the exchangeable, carbonates, organic matter/sulfides and residual fractions was determined using a sequential extraction procedure (modified Tessier). Experimental equilibrium sorption data for cobalt were analysed by the Langmuir, Freundlich and Redlich¿Peterson isotherm equations. The total Langmuir maximal sorption capacity of the sludge fed with glucose and sulfate loaded with cobalt alone displayed a significantly higher maximal cobalt sorption (Qmax = 18.76 mg g¿1 TSS) than the sludge fed with glucose alone (Qmax = 13.21 mg g¿1 TSS), essentially due to an increased sorption capacity of the exchangeable (30¿107%) and organic/sulfides fractions (70¿30%). Environmental scanning electron microscopy coupled with an energy dispersive X-ray analysis of granular cross-sections showed that mainly iron minerals (i.e. iron sulfides) were involved in the cobalt accumulation. Moreover, the sorbed cobalt was mainly located at the edge of the granules. The sorption characteristics of the exchangeable and carbonates fractions fitted well to the Redlich¿Peterson model (intermediate multi-layer sorption behaviour), whereas the sorption characteristics of the organic matter/sulfides and residual fractions fitted well to the Langmuir model (monolayer sorption behaviour). The organic matter/sulfides fraction displayed the highest affinity for cobalt for the three sludge types investigated
NO Removal in Continuous BioDeNOx Reactors: Fe(II)EDTA2- Regeneration, Biomass Growth, and EDTA Degradation
Maas, P.M.F. van der; Brink, P. van den; Utomo, S. ; Klapwijk, A. ; Lens, P.N.L. - \ 2006
Biotechnology and Bioengineering 94 (2006)3. - ISSN 0006-3592 - p. 575 - 584.
nitric-oxide - ethylenediaminetetraacetic acid - biological denitrification - reduction - absorption - iron - methanogenesis - oxidation - kinetics - sulfide
BioDeNOx is a novel technique for NOx removal from industrial flue gases. In principle, BioDeNOx is based on NO absorption into an aqueous Fe(II)EDTA2- solution combined with biological regeneration of that scrubber liquor in a bioreactor. The technical and economical feasibility of the BioDeNOx concept is strongly determined by high rate biological regeneration of the aqueous Fe(II)EDTA2- scrubber liquor and by EDTA degradation. This investigation deals with the Fe(II)EDTA2- regeneration capacity and EDTA degradation in a lab-scale BioDeNOx reactor (10-20 mM Fe(II)EDTA2-, pH 7.2 ± 0.2, 55°C), treating an artificial flue gas (1.5 m3/h) containing 60-155 ppm NO and 3.5-3.9% O2. The results obtained show a contradiction between the optimal redox state of the aqueous FeEDTA solution for NO absorption and the biological regeneration. A low redox potential (below -150 mV vs. Ag/AgCl) is needed to obtain a maximal NO removal efficiency from the gas phase via Fe(II)EDTA2- absorption. Fe(III)EDTA- reduction was found to be too slow to keep all FeEDTA in the reduced state. Stimulation of Fe(III)EDTA- reduction via periodical sulfide additions (2 mM spikes twice a week for the conditions applied in this study) was found to be necessary to regenerate the Fe(II)EDTA2- scrubber liquor and to achieve stable operation at redox potentials below -150 mV (pH 7.2 ± 0.2). However, redox potentials of below -200 mV should be avoided since sulfide accumulation is unwanted because it is toxic for NO reduction. Very low values for biomass growth rate and yield, respectively, 0.043/d and 0.009 mg protein per mg ethanol, were observed. This might be due to substrate limitations, that is the electron acceptors NO and presumably polysulfide, or to physiological stress conditions induced by the EDTA rich medium or by radicals formed in the scrubber upon the oxidation of Fe(II)EDTA2- by oxygen present in the flue gas. Radicals possibly also induce EDTA degradation, which occurs at a substantial rate: 2.1 (±0.1) mM/d under the conditions investigated
Effect of Cobalt Sorption on Metal Fractionation in Anaerobic Granular Sludge
Osuna, M.B. ; Hullebusch, E.D. van; Zandvoort, M.H. ; Iza, J.M. ; Lens, P.N.L. - \ 2004
Journal of Environmental Quality 33 (2004)4. - ISSN 0047-2425 - p. 1256 - 1270.
trace-metals - heavy-metals - h-1-nmr characterization - diffusional properties - sequential extraction - digested-sludge - sediments - binding - precipitation - sulfide
A sequential extraction procedure was applied to two anaerobic methanogenic sludges (Eerbeek and Nedalco) to examine the speciation of micro- and macronutrients in the sludges after cobalt sorption by exposing the sludge to a 1 mM Co solution for 4 d at pH 7 and 30degreesC. The effect of different physicochemical conditions on cobalt sorption was studied as well: effect of pH (6-8), effect of competition by a second trace element (Ni or Fe), modification of the granular matrix by glutaraldehyde or heat treatment, and EDTA (ethylenediaminetetraacetic acid) addition. Sorbed Co was found to distribute between the carbonates, organic matter + sulfides, and residual fractions. Cobalt adsorption resulted in an antagonistic interaction with other metals present in the granular matrix, evidenced by the solubilization of other trace elements (e.g., Ni, Cu, and Zn) as well as macronutrients (especially Ca and Fe). Modification of the sludge matrix by glutaraldehyde or heat treatment, or exposure to EDTA, led to serious modifications of the Co sorption capacity and strong interactions with multivalent cations (i.e., Ca2+ and Fe2+).
Methanol utilization in defined mixed cultures of thermophilic anaerobes in the presence sulfate
Goorissen, H.P. ; Stams, A.J.M. ; Hansen, T.A. - \ 2004
FEMS Microbiology Ecology 49 (2004)3. - ISSN 0168-6496 - p. 489 - 494.
sp-nov - reducing bacterium - reactor - reduction - hydrogen - sulfide - strains
We studied thermophilic sulfate reduction with methanol as electron donor in continuous cultures. Mixed cultures of selected microorganisms were used, representing different methanol degrading pathways followed by various trophic groups of microorganisms. Our results show that direct competition for methanol between a homoacetogen, Moorella thermoautotrophica, and a sulfate reducer, Desulfotomaculum kuzrietsovii, is in favour of the sulfate reducer due to its affinity for methanol. Methanogenesis as a result of interspecies hydrogen transfer between D. kuznetsovii and a hydrogen-consuming methanogenic archaeon, Methanothermobacter thermoautotrophicus occurred only below 5 mM total sulfide. A similar result was obtained when M. thermoautotrophica was grown on methanol in the presence of Mb. thermoautotrophicus. Interestingly, D. kuznetsovii could coexist with a non-methanolutilizing sulfate reducer (Thermodesulfovibrio species). Our data show that it is possible to maintain a dominant sulfate-reducing process with methanol as electron donor at 60 degreesC in mixed continuous cultures. (C) 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
Development of a novel Process for the Biological conversion of H2S and Methanethiol to Elemental Sulfur
Sipma, J. ; Janssen, A.J.H. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2003
Biotechnology and Bioengineering 82 (2003)1. - ISSN 0006-3592 - p. 1 - 11.
afvalwaterbehandeling - anaërobe behandeling - zwavel - rioolafvalwater - slib - methanol - reductie - bioreactoren - waste water treatment - anaerobic treatment - sulfur - sewage effluent - sludges - reduction - bioreactors - granular sludge reactor - methylotrophic methanogen - sp-nov - waste-water - estuarine methanogen - sulfide - degradation - sediments - dimethylsulfide - bacterium
The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges were tested for their ability to degrade MT
The feasibility of anaerobic treatment of wastewater containing methanethiol (MT), an extremely volatile and malodorous sulfur compound, was investigated in lab-scale bioreactors. Inoculum biomass originating from full-scale anaerobic wastewater treatment facilities was used. Several sludges, tested for their ability to degrade MT, revealed the presence of organisms capable of metabolizing MT as their sole source of energy. Furthermore, batch tests were executed to gain a better understanding of the inhibition potential of MT. It was found that increasing MT concentrations affected acetotrophic organisms more dramatically than methylotrophic organisms. Continuous reactor experiments, using two lab-scale upflow anaerobic sludge bed (UASB) reactors (R1 and R2), aimed to determine the maximal MT load and the effect of elevated sulfide concentrations on MT conversion. Both reactors were operated at a hydraulic retention time (HRT) of about 7 hours, a temperature of 30degreesC, and a pH of between 7.3 and 7.6. At the highest influent MT concentration applied, 14 mM in R1, corresponding to a volumetric loading rate of about 50 mM MT per day, 87% of the organic sulfur was recovered as hydrogen sulfide (12.2 mM) and the remainder as volatile organic sulfur compounds (VOSCs). Upon decreasing the HRT to 3.5 to 4.0 h at a constant MT loading rate, the sulfide concentration in the reactor decreased to 8 mM and MT conversion efficiency increased to values near 100%. MT conversion was apparently inhibited by the high sulfide concentrations in the reactor. The specific MT degradation rate, as determined after 120 days of operation in R1, was 2.83 +/- 0.27 mmol MT g VSS-1 day(-1). During biological desulfurization of liquid hydrocarbon phases, such as with liquefied petroleum gas (LPG), the combined removal of hydrogen sulfide and MT is desired. In R2, the simultaneous addition of sodium sulfide and MT was therefore studied and the effect of elevated sulfide concentrations was investigated. The addition of sodium sulfide resulted in enhanced disintegration of sludge granules, causing significant washout of biomass. Additional acetate, added to stimulate growth of methanogenic bacteria to promote granulation, was hardly converted at the termination of the experimental period. (C) 2003 Wiley Periodicals, Inc.
Long-term adaptation of methanol-fed thermophilic (55°C) sulfate-reducing reactors to NaCl
Vallero, M.V.G. ; Lettinga, G. ; Lens, P.N.L. - \ 2003
Journal of Industrial Microbiology and Biotechnology 30 (2003). - ISSN 1367-5435 - p. 375 - 382.
anaerobic treatment - saline wastewaters - sodium inhibition - bed reactor - factories - reduction - sulfide
A laboratory-scale upflow anaerobic sludge bed (UASB) reactor was operated during 273 days at increasing NaCl concentrations (0.5-12.5 g NaCl l(-1)) to assess whether the stepwise addition of the salt NaCl results in the acclimation of that sludge. The 6.5-1 thermophilic (55 degreesC), sulfidogenic [a chemical oxygen demand (COD) to SO42- ratio of 0.5] UASB reactor operated at an organic loading rate of 5 g COD l(-1) day(-1), a hydraulic retention time of 10 h and was fed with methanol as the sole electron donor. The results show that the adaptation of the thermophilic, sulfidogenic methanol-degrading biomass to a high osmolarity environment is unlikely to occur. Sulfide was the main mineralization product from methanol degradation, regardless of the NaCl concentration added to the influent. However, sulfide production in the reactor steadily decreased after the addition of 7.5 g NaCl l(-1), whereas acetate production was stimulated at that influent NaCl concentration. Batch tests performed with sludge harvested from the UASB reactor when operating at different influent salinities confirmed that acetate is the main metabolic product at NaCl concentrations higher than 12.5 g l(-1). The apparent order of NaCl toxicity towards the different trophic groups was found to be: sulfate-reducing bacteria > methane-producing archaea > acetogenic bacteria.