Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Exploring the ecophysiology of anaerobic communities of methanotrophic archaea and sulfate-reducing bacteria
    Timmers, P.H.A. - \ 2015
    Wageningen University. Promotor(en): Fons Stams, co-promotor(en): Caroline Plugge. - Wageningen : Wageningen University - ISBN 9789462575820 - 181
    sulfate reducing bacteria - methane - oxidation - anaerobic conditions - sulfates - marine sediments - microbial physiology - sulfaat reducerende bacteriën - methaan - oxidatie - anaërobe omstandigheden - sulfaten - mariene sedimenten - microbiële fysiologie

    Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) is a widespread occurring process in anoxic marine sediments. The process is performed by ANaerobic MEthane oxidizing archaea (ANME) and associated sulfate reducing bacteria (SRB). The ANME presumably oxidize methane through reverse methanogenesis. The associated SRB were thought to reduce sulfate using an interspecies electron carrier (IEC) derived from AOM. The product of methane oxidation that is transferred to the SRB is either a less reduced compound that acts as IEC or electrons are transferred directly (through nanowires or pili) or indirectly (through extracellular quinones). However, recent evidence emerged that ANME could perform both methane oxidation and sulfate reduction to produce sulfur, where the SRB disproportionate the produced sulfur. Little is known on the physiology and ecology of these ANME and associated SRB. The main reasons for this are the difficulties in lab cultivation and to perform in situ studies.

    Anaerobic methane oxidation is a process that is at the border of what is energetically possible for sustaining life, which makes it hard to cultivate the responsible organisms. Estimates of the Gibbs free energy yields are between -18 and -35 kJ mol-1 and growth rates between 1.1 and 7.5 months, depending on the environment. AOM therefore operates close to thermodynamic equilibrium and is highly dependent on substrate and product concentrations. In chapter 2, we obtained faster growth rates at elevated methane partial pressure as compared to ambient pressure. The increase in partial pressure increased the solubility of methane and thus the energy yield for the organisms. In chapter 6, we showed higher AOM activity and growth of ANME under thermodynamically favorable sulfate and sulfide concentrations. The problems in studying the process in situ in complex environments comes from difficulties in differentiation of reversible processes. In most studies, methane oxidation is monitored by labelled CO2 formation from labelled methane. Methanogens can perform trace methane oxidation (TMO)during net methanogenesis, which also results in the production of labelled CO2 from labelled methane. When AOM becomes less favorable, the anaerobic back flux of AOM becomes significant, leading to the production of measurable amounts of methane. In chapter 2 and chapter 3, we were able to differentiate between AOM and TMO in long-term incubations.

    Another challenge is related to the detection of ANME in complex environments. The phylogenetic distance between and within ANME clades is large. In chapter 5, we discussed the difficulties in primer and probe design for selective detection of ANME without targeting closely related methanogens. Furthermore, it is not known if even more ANME species and clades have yet to be discovered that are not detected with the primers and probes used thus far. In chapter 3, we found indications that besides ANME-2a/b, ANME-2d archaea were also able to perform AOM coupled to sulfate reduction in freshwater conditions. The finding of ANME-2a/b in freshwater shows that ANME archaea are ubiquitously distributed and not only occur in marine sediments. In chapter 6, we confirmed that different ANME clades show niche separation based on the presence of methane and different sulfate and sulfide concentrations. In chapter 2, we obtained indications that ANME-2c grows at high methane partial pressure. More research on the ecophysiology could help in understanding occurrence and activity of ANME in different environments.

    Many different SRB have been found so far to form close associations with ANME. Most fall within the Desulfosarcina/Desulfococcus (DSS) clade and only for two enrichment cultures the dominant partner of ANME-2a/b was determined to belong to a specific group with the DSS named SEEP-SRB1. In chapter 2, we found more evidence that a group outside the DSS clade, SEEP-SRB2, could also associate with ANME-2a/b and that Eel-1 members are not directly involved in AOM. In chapter 4, we enriched for SRB within the DSS clade on alternative substrates besides methane, but we were unable to show that these are involved in AOM. Therefore, more research on the sulfate-reducing partner is needed to understand the metabolic interactions between ANME and SRB.

    Anaerobic oxidation of methane : evaluation of alternative conditions
    Suarez Zuluaga, D.A. - \ 2015
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Jan Weijma. - Wageningen : Wageningen University - ISBN 9789462574823 - 131
    microorganisms - methane - oxidation - sulfates - reduction - bioreactors - micro-organismen - methaan - oxidatie - sulfaten - reductie - bioreactoren

    Microorganisms capable of performing anaerobic oxidation of methane (AOM) coupled to sulphate reduction have high doubling times which make their enrichment difficult. However, due to higher energy gain, they might be rapidly enriched using alternative electron acceptors. In chapter 2, it was shown that up to 50 times higher conversion rates were obtained with thiosulphate when compared to sulphate. However, it was also presented that thiosulphate was not be exclusively used by microorganisms that reduce it, but that it was also disproportionated into sulphate and sulphide (Chapter 2).

    In Chapter 3, a 5 litre membrane bioreactor was fed not only with methane and sulphate but also with acetate and thiosulphate. As previous experiments using these additional substrates had allowed to obtain either faster conversion rates or enrichment of methanotrophic microorganisms; it was expected that AOM rates in the reactor would increase relatively fast. However, the microorganisms that were enriched were not AOM related. They microbial community that showed the highest activity rates in the reactor was comprised by thiosulphate disproportionated bacteria and green sulphur bacteria. The former disproportionated thiosulphate into sulphate and sulphide while the latter converted the sulphide into elemental sulphur.

    Chapter 4, unlike the previous chapters, focused on studying the occurrence of AOM in a fresh water ecosystem. Such system was located next to a natural gas source which captured methane for domestic purposes. It was presented how, with the different electron acceptors added, AOM and trace methane oxidation occurred. However, net AOM was only measured in the presence of sulphate as electron acceptor. Furthermore, the microorganisms that were enriched in the presence of methane and sulphate were also detected.

    There are several hypotheses which attempted to explain the AOM coupled to sulphate reduction. One of them indicates that it is a process that involves two microorganisms working in a syntrophic relationship. The first microorganism would convert the methane into carbon dioxide and pass the electrons to the second one. Consequently, the second microorganism would convert the sulphate into hydrogen sulphide. In such a structure, the way that electrons are released by the conversion performed by the first microorganism is unknown. It is possible, that electrons are not transfer via electron shuttles or chemical compounds, but that they are transferred directly from one microorganism to the other. A methodology which could be used to determine if the AOM consortia uses direct electron transfer mechanisms was evaluated in Chapter 5. Different kinds of granular biomass were used for this evaluation and, the granule types that would potentially be capable of using direct electron transfer mechanisms were detected.

    Zwaveldynamiek in het West-Nederlandse laagveengebied : met het oog op klimaatverandering
    Vermaat, J. ; Harmsen, J. ; Hellmann, F. ; Geest, H. van der; Klein, J.J.M. de; Kosten, S. ; Smolders, F. ; Verhoeven, J. - \ 2012
    Amsterdam : Vrije Universiteit - 83
    veenweiden - oppervlaktewater - eutrofiëring - sulfaten - natuurgebieden - klimaatverandering - west-nederland - peat grasslands - surface water - eutrophication - sulfates - natural areas - climatic change - west netherlands
    Sulfaatconcentraties in het oppervlaktewater van het West-Nederlandse laagveengebied kunnen bijzonder hoog zijn. Er bestaat onduidelijkheid over de bronnen en de effecten van dit sulfaat. De huidige studie combineert jaarbalansen op perceel-, polder- en stroomgebiedsschaal met een analyse van de ruimtelijke variatie in sulfaatconcentraties, en met een literatuurstudie naar kritische drempelconcentraties voor eutrofiëring, toxiciteit, en de ontwikkeling van gewenste laagveennatuur. De bevindingen worden gecombineerd met KNMI klimaatscenario’s zodat de effecten van klimaatsveranderingen kunnen worden ingeschat.
    Sulfate reduction at low pH in organic wastewaters
    Lopes, S.I.C. - \ 2007
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): P. Lens; M.I. Capela. - [S.l.] : S.n. - ISBN 9789085047636 - 244
    afvalwaterbehandeling - ph - verzuring - sulfaten - anaërobe behandeling - sulfaatreductie - waste water treatment - ph - acidification - sulfates - anaerobic treatment - sulfate reduction
    The objective of the research described in this thesis was to investigate the operational window of dissimilatory sulfate reduction at low pH (6, 5 and 4) during the acidification of organic wastewaters. High sulfate reduction efficiencies at low pH are desirable for a more sustainable operation of acidification reactors in a two-phase wastewater treatment system, as pH control requires less caustic and/or the effluent recirculation from the second (methanogenic) reactor can be skipped. The low pH would also facilitate the removal of sulfide by stripping, as the fraction of gaseous sulfide increases with decreasing pH
    Volatile organic sulfur compounds in anaerobic sludge and sediments: biodegradation and toxicity
    Leerdam, R.C. van; Bok, F.A.M. de; Lomans, B.P. ; Stams, A.J.M. ; Lens, P.N.L. ; Janssen, A.J.H. - \ 2006
    Environmental Toxicology and Chemistry 25 (2006)12. - ISSN 0730-7268 - p. 3101 - 3109.
    microbiële afbraak - slib - sediment - anaërobe behandeling - afvalwaterbehandeling - sulfaten - thiolen - reductie - sulfaat - methanol - biodegradatie - microbial degradation - sludges - sediment - anaerobic treatment - waste water treatment - sulfates - thiols - reduction - sulfate - methanol - biodegradation - fresh-water sediments - dimethyl sulfide - membrane bioreactor - waste air - methanethiol - degradation - inhibition - removal - ph - methanogens
    A variety of environmental samples was screened for anaerobic degradation of methanethiol, ethanethiol, propanethiol, dimethylsulfide, and dimethyldisulfide. All sludge and sediment samples degraded methanethiol, dimethylsulfide, and dimethyldisulfide anaerobically. In contrast, ethanethiol and propanethiol were not degraded by the samples investigated under any of the conditions tested. Methanethiol, dimethylsulfide, and dimethyldisulfide were mainly degraded by methanogenic archaea. In the presence of sulfate and the methanogenic inhibitor bromoethane sulfonate, degradation of these compounds coupled to sulfate reduction occurred as well, but at much lower rates. Besides their biodegradability, also the toxicity of methanethiol, ethanethiol, and propanethiol to methanogenesis with methanol, acetate, and H2/CO2 as the substrates was assessed. The 50% inhibition concentration of methanethiol on the methane production from these substrates ranged between 7 and 10 mM. The 50% inhibition concentration values of ethanethiol and propanethiol for the degradation of methanol and acetate were between 6 and 8 mM, whereas hydrogen consumers were less affected by ethanethiol and propanethiol, as indicated by their higher 50% inhibition concentration (14 mM). Sulfide inhibited methanethiol degradation already at relatively low concentrations: methanethiol degradation was almost completely inhibited at an initial sulfide concentration of 8 mM. These results define the operational limits of anaerobic technologies for the treatment of volatile organic sulfur compounds in sulfide-containing wastewater streams
    Pyrietvorming in relatie tot interne eutrofiëring en verzuring
    Delft, S.P.J. van; Kemmers, R.H. ; Jongmans, A.G. - \ 2005
    Wageningen : Alterra (Alterra-rapport 1161) - 88
    vegetatie - bodemchemie - fosfaten - kwel - eutrofiëring - sulfaten - pyriet - natuur - vegetation - soil chemistry - phosphates - seepage - eutrophication - sulfates - pyrites - nature
    In natte natuurgebieden wordt steeds vaker oppervlakkig pyriet aangetroffen in de bodem. Dit wijst op interne eutrofiering, waarbij sulfaat en ijzer worden gereduceerd en stikstof en fosfaat vrijkomen. Doel van het onderzoek was de ernst en omvang van dit probleem te verkennen. Daartoe werd op 32 standplaatsen in 14 natuurgebieden de pyrietvoorraad in de bodem geanalyseerd. De pyrietvoorraad kan zowel verklaard worden uit de aanvoer van sulfaat via atmosferische depositie sinds 1880 als uit toestroming via lokale kwelsystemen sinds de afgelopen halve eeuw. Micromorfologisch onderzoek toonde aan dat pyrietvorming een actueel proces is, maar kon geen uitsluitsel geven over de herkomst. Via regressieanalyse werden de sleutelfactoren voor pyrietvorming en interne eutrofiering bepaald. Onderzocht werd in welke mate het gevormde pyriet de fosfaatbindingscapaciteit en de fosfaatmobilisatie beïnvloed kan hebben. Uit het onderzoek blijkt dat bij vernatting het sulfaateffect dat door de aanwezigheid van pyriet kan worden verklaard een veelvoud kleiner is dan het vernattingseffect op zich zelf. Lokaal kunnen echter ernstige problemen ontstaan
    Thermophilic (55 - 65°C) and extreme thermophilic (70 - 80°C) sulfate reduction in methanol and formate-fed UASB reactors
    Vallero, M.V.G. ; Camarero, E. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
    Biotechnology Progress 20 (2004)5. - ISSN 8756-7938 - p. 1382 - 1392.
    anaërobe behandeling - afvalwaterbehandeling - methanol - reductie - sulfaten - temperatuur - anaerobic treatment - waste water treatment - methanol - reduction - sulfates - temperature - rate anaerobic reactor - volatile fatty-acids - 55-degrees-c - sludge - degradation - conversion - bacterium - methanogenesis - competition - performance
    The feasibility of thermophilic (55-65 degreesC) and extreme thermophilic (70-80 degreesC) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures
    The feasibility of thermophilic (55-65 degreesC) and extreme thermophilic (70-80 degreesC) sulfate-reducing processes was investigated in three lab-scale upflow anaerobic sludge bed (UASB) reactors fed with either methanol or formate as the sole substrates and inoculated with mesophilic granular sludge previously not exposed to high temperatures. Full methanol and formate degradation at temperatures up to, respectively, 70 and 75 degreesC, were achieved when operating UASB reactors fed with sulfate rich (COD/SO42- = 0.5) synthetic wastewater. Methane-producing archaea (MPA) outcompeted sulfate-reducing bacteria (SRB) in the formate-fed UASB reactor at all temperatures tested (65-75 degreesC). In contrast, SRB outcompeted MPA in methanol-fed UASB reactors at temperatures equal to or exceeding 65 degreesC, whereas strong competition between SRB and MPA was observed in these reactors at 55 degreesC. A short-term (5 days) temperature increase from 55 to 65 degreesC was an effective strategy to suppress methanogenesis in methanol-fed sulfidogenic UASB reactors operated at 55 degreesC. Methanol was found to be a suitable electron donor for sulfate-reducing processes at a maximal temperature of 70 degreesC, with sulfide as the sole mineralization product of methanol degradation at that temperature.
    In-situ metal precipitation in a zinc-aerobic, sandy aquifer by means of biological sulfate reduction
    Janssen, G.M.C.M. ; Temminghoff, E.J.M. - \ 2004
    Environmental Science and Technology 38 (2004)14. - ISSN 0013-936X - p. 4002 - 4011.
    terugwinning - sulfaten - neerslag - kooldioxide - decontaminatie - waterverontreiniging - watervoerende lagen - biologische behandeling - zware metalen - zink - recovery - sulfates - precipitation - carbon dioxide - decontamination - water pollution - aquifers - biological treatment - heavy metals - zinc - acid-mine drainage - reducing bacteria - removal - carbon - water - reactor - effluent - ethanol - energy - growth
    The applicability of in situ metal precipitation (ISMP) based on bacterial sulfate reduction (BSR) with molasses as carbon source was tested for the immobilization of a zinc plume in an aquifer with highly unsuitable initial conditions (high Eh, low pH, low organic matter content, and low sulfate concentrations), using deep wells for substrate injection
    The applicability of in situ metal precipitation (ISMP) based on bacterial sulfate reduction (BSR) with molasses as carbon source was tested for the immobilization of a zinc plume in an aquifer with highly unsuitable initial conditions (high E-h, low pH, low organic matter content, and low sulfate concentrations), using deep wells for substrate injection. Batch experiments revealed an optimal molasses concentration range of 1-5 g/L and demonstrated the necessity of adding a specific growth medium to the groundwater. Without this growth medium, even sulfate, nitrogen, phosphorus, and potassium addition combined with pH optimization could not trigger biological sulfate reduction. In column experiments, precipitation of ZnS(s) was induced biologically as well as chemically (by adding Na2S). In both systems, zinc concentrations dropped from about 30 mg/L to below 0.02 mg/L. After termination of substrate addition the biological system showed continuation of BSR for at least 2 months, suggesting the insensitivity of the sulfate reducing system for short stagnations of nutrient supply, whereas in the chemical system an immediate increase of Zn concentrations was observed. A pilot experiment conducted in situ at the zinc-contaminated site showed a reduction of zinc concentrations from around 40 mg/L to below 0.01 mg/L. Termination of substrate supply did not result in an immediate stagnation of the BSR process, but continuation of BSR was observed for at least 5 weeks.
    Effect of specific gas loading rate on thermophilic (55°) acidifying (pH6) and sulfate reducing granular sludge reactors
    Lens, P.N.L. ; Klijn, R. ; Lier, J.B. van; Lettinga, G. - \ 2003
    Water Research 37 (2003). - ISSN 0043-1354 - p. 1033 - 1047.
    afvalwaterbehandeling - anaërobe behandeling - temperatuur - verzuring - sulfaten - reductie - anaërobe afbraak - waste water treatment - anaerobic treatment - temperature - acidification - sulfates - reduction - anaerobic digestion - fatty-acid degradation - waste-water treatment - anaerobic-digestion - blanket reactors - uasb reactors - system - methanogenesis - velocity - sulfide
    The effect of the specific gas loading rate on the acidifying, sulfate reducing and sulfur removal capacity of thermophilic (55degreesC; pH 6.0) granular sludge bed reactors treating partly acidified wastewater was investigated. A comparison was made between a regular UASB reactor and a UASB reactor continuously sparged with N-2 at a specific gas loading rate of 30 m(3) m(-2) d(-1). Both UASB reactors (upflow velocity 1.0 m h(-1), hydraulic retention time about 5 h) were fed a synthetic wastewater containing starch, sucrose, lactate, propionate and acetate and a low sulfate concentration (COD/SO42- ratio of 10) at volumetric organic loading rates (OLR) ranging from 4.0 to 49.8 gCOD l(-1) reactor d(-1). Immediately after imposing an OLR of 25 gCOD l(-1) reactor d(-1), the acidification and sulfate reduction efficiency dropped to 80% and 30%, respectively, in the UASB reactor. Both efficiencies recovered slowly to 100% during the course of the experiment. In the N-2 SParged reactor, both the acidification and sulfate reduction efficiency remained 100% following the OLR increase to 25 gCOD l(-1) reactor d(-1). However, the sulfate reduction efficiency gradually decreased to about 20% at the end of the experiment. The biogas (CO2 and CH4) production rate in the UASB was very low,-i.e.
    Effect of NaCl on thermophilic (55°C) methanol degradation in sulfate reducing granular sludge reactors
    Vallero, M.V.G. ; Hulshoff Pol, L.W. ; Lettinga, G. ; Lens, P.N.L. - \ 2003
    Water Research 37 (2003)10. - ISSN 0043-1354 - p. 2269 - 2280.
    anaërobe behandeling - afvalwaterbehandeling - methanol - reductie - natriumchloride - sulfaten - rioolafvalwater - slib - anaerobic treatment - waste water treatment - methanol - reduction - sodium chloride - sulfates - sewage effluent - sludges - sp-nov - processing wastewaters - sodium inhibition - bacteria - methanogenesis - temperature - antagonism - digestion
    The effect of NaCl on thermophilic (55degreesC) methanol conversion in the presence of excess of sulfate (COD/SO42-=0.5) was investigated in two 6.5L lab-scale upflow anaerobic sludge bed reactors inoculated with granular sludge previously not adapted to NaCl
    The effect of NaCl on thermophilic (55degreesC) methanol conversion in the presence of excess of sulfate (COD/SO42-=0.5) was investigated in two 6.5L lab-scale upflow anaerobic sludge bed reactors inoculated with granular sludge previously not adapted to NaCl. Methanol was almost completely used for sulfate reduction in the absence of NaCl when operating at an organic loading rate of 5 g COD L-1 day(-1) and a hydraulic retention time of 10 h. The almost fully sulfidogenic sludge consisted of both granules and flocs developed after approximately 100 days in both reactors. Sulfate reducing bacteria (SRB) outcompeted methane producing archaea (MPA) for methanol, but acetate represented a side-product, accounting for maximal 25% of the total COD converted. Either MPA or SRB did not use acetate as substrate in activity tests. High NaCl concentrations (25 g L-1) completely inhibited methanol degradation, whereas low salt concentrations (2.5 g NaCl L-1) provoked considerable changes in the metabolic fate of methanol. The MPA were most sensitive towards the NaCl shock (25 g L-1). In contrast, the addition of 2.5 g L-1 of NaCl stimulated MPA and homoacetogenic bacteria. (C) 2003 Elsevier Science Ltd. All rights reserved.
    Assessment of compatible solutes to overcome salinity stress in thermophilic (55 oC) methanol-fed sulfate reducing granular sludges
    Vallero, M.V.G. ; Lettinga, G. ; Lens, P.N.L. - \ 2003
    Water Science and Technology 48 (2003)6. - ISSN 0273-1223 - p. 195 - 202.
    anaërobe behandeling - afvalwaterbehandeling - methanol - reductie - natriumchloride - sulfaten - rioolafvalwater - slib - anaerobic treatment - waste water treatment - methanol - reduction - sodium chloride - sulfates - sewage effluent - sludges - glycine betaine - growing-cells - accumulation - degradation - adaptation - trehalose - glutamate - reactor
    High NaCl concentrations (25 g.L-1) considerably decreased the methanol depletion rates for sludges harvested from two lab-scale sulfate reducing UASB reactors. In addition, 25 gNaCl.L-1 strongly affected the fate of methanol degradation, with clear increase in the acetate production at the expense of sulfide and methane production. The addition of different osmoprotectants, viz. glutamate, betaine, ectoine, choline, a mixture of compatible solutes and K+ and Mg2+, slightly increased methanol depletion rates for UASB reactors sludges. However, the acceleration in the methanol uptake rate favored the homoacetogenic bacteria, as the methanol breakdown was steered to the formation of acetate without increasing sulfate reduction and methane production rates. Thus, the compatible solutes used in this work were not effective as osmoprotectants to alleviate the acute NaCl toxicity on sulfate reducing granular sludges developed in methanol degrading thermophilic (55°C) UASB reactors
    High NaCl concentrations (25 g(.)L(-1)) considerably decreased the methanol depletion rates for sludges harvested from two lab-scale sulfate reducing UASB reactors. In addition, 25 gNaCl.L-1 strongly affected the fate of methanol degradation, with clear increase in the acetate production at the expense of sulfide and,methane production. The addition of different osmoprotectants, viz. glutmate, betaine, ectoine, choline, a mixture of compatible solutes and K+ and Mg2+, slightly increased methanol depletion rates for UASB reactors sludges. However, the acceleration in the methanol uptake rate favored the homoacetogenic bacteria, as the methanol breakdown was steered to the formation of acetate without increasing sulfate reduction and methane production rates. Thus, the compatible solutes used in this work were not effective as osmoprotectants to alleviate the acute NaCl toxicity on sulfate reducing granular sludges developed in methanol degrading thermophilic (55degreesC) UASB reactors.
    Sulfidogenic volatile fatty acid degradation in a baffled reactor
    Vallero, M.V.G. ; Lens, P.N.L. ; Bakker, C. ; Lettinga, G. - \ 2003
    Water Science and Technology 48 (2003)3. - ISSN 0273-1223 - p. 81 - 88.
    anaërobe afbraak - rioolslib - anaërobe behandeling - sulfaten - vluchtige vetzuren - afvalwaterbehandeling - anaerobic digestion - sewage sludge - anaerobic treatment - sulfates - volatile fatty acids - waste water treatment - granular sludge reactor - methanogenic bacteria - waste-water - competition - abr
    The effect of staging the sludge bed on volatile fatty acid degradation by sulfidogenic reactors was evaluated in a baffled reactor
    The effect of staging the sludge bed on volatile fatty acid degradation by sulfidogenic reactors was evaluated in a baffled reactor. In a 5.41 baffled reactor, containing three equal compartments, a volatile fatty acid (VFA) mixture (acetate: propionate:butyrate ratio 1:2:2 on COD basis; pH 8) was treated under mesophilic (30 degreesC) and sulfidogenic (COD:SO42- ratio: 0.5) conditions for 38 days. At a specific sludge loading rate of 0.50 g COD.gVSS(-1).d(-1), a COD and sulfate removal of 85% and 30%, respectively, was obtained. In the baffled reactor, staging of the sulfidogenic VFA degradation occurred. Propionate and butyrate were mainly degraded in the first compartment. Their degradation was incomplete, resulting in elevated acetate concentrations in compartment I. In the second and third compartment of the baffled reactor, a net degradation of acetate took place. Acetate was the sole substrate present in compartment III and residual acetate concentrations of about 200 mg/l were present in the effluent at a specific sludge loading of 0.50 g COD.gVSS(-1).d(-1). Sludges with different maximum specific VFA and acetate degrading activities developed in the first and second compartment. These maximal specific activities were almost equal for sludge present in compartment II and III.
    Optimisation of sulphate reduction in a methanol-fed thermophilic bioreactor
    Weijma, J. ; Bots, E.A.A. ; Tandlinger, G. ; Stams, A.J.M. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2002
    Water Research 36 (2002). - ISSN 0043-1354 - p. 1825 - 1833.
    afvalwaterbehandeling - anaërobe behandeling - sulfaten - methanol - reductie - slib - waste water treatment - anaerobic treatment - sulfates - methanol - reduction - sludges
    Several methods were tested to optimise sulphate reduction and minimise methane formation in thermophilic (65°) expanded granular sludge bed reactors fed with a medium containing sulphate and methanol. Lowering the pH from 7.5 to 6.75 resulted in a rapid decrease of methane formation and a concomitant increase in sulphate reduction. The inhibition of methane formation was irreversible on the short-term. Lowering the COD/SO42- ratio (COD: chemical oxygen demand) from 6 to 0.34 (g/g) rapidly favoured sulphate reduction over methanogenesis. Continuous addition of 2 g L-1 2-bromoethanesulphonate was ineffective as complete inhibition of methanogenesis was obtained only for two days. Inhibition of methanogens by sulphide at pH 7.5 was only effective when the total sulphide concentration was above 1200 mg S L-1. For practical applications, a relatively short exposure to a slightly acidic pH in combination with operating the reactor at a volumetric methanol-COD loading rate close to the maximum volumetric sulphide-COD formation rate.
    Modelling the competition between sulphate reducers and methanogens in a thermophilic methanol-fed bioreactor
    Spanjers, H. ; Weijma, J. ; Abusam, A. - \ 2002
    Water Science and Technology 45 (2002)10. - ISSN 0273-1223 - p. 93 - 98.
    rioolslib - afvalwaterbehandeling - methanol - sulfaten - reductie - anaërobe behandeling - afvalwater - micro-organismen - sewage sludge - waste water treatment - methanol - sulfates - reduction - anaerobic treatment - waste water - microorganisms
    Sulphate can be removed from wastewater by means of biological anaerobic reduction to sulphide. The reduction requires the presence of a substrate that can serve as an electron donor. Methanol a suitable electron donor for sulphate reduction under thermophilic conditions. In an anaerobic system containing methanol and sulphate, acetogenic bacteria (AB) and methanogenic archaea (MA) compete with sulphate reducing bacteria (SRB) for methanol or its degradation intermediates. Previously obtained results indicate that at 65 degrees C SRB and MA mainly compete for the intermediate hydrogen instead of methanol. For efficient use of methanol as electron donor for sulphate reduction it is important that for the treatment of sulphate wastewater in an anaerobic reactor SRB out-compete MA. The mechanisms that determine the outcome of the competition are, however, not well understood. This paper describes a model based on growth kinetics of methanol-oxidising AB, and hydrogen-consuming SRB and MA, that can describe the competition between SRB and MA in a methanol-fed bioreactor. We present the model and its calibration using experimental data, and we discuss its shortcomings and suggest possible improvements.
    Competition for H2 between sulfate reducers, methanogens and homoacetogens in a gas-lift reactor
    Weijma, J. ; Gubbels, F. ; Hulshoff Pol, L.W. ; Stams, A.J.M. ; Lens, P.N.L. ; Lettinga, G. - \ 2002
    Water Science and Technology 45 (2002). - ISSN 0273-1223 - p. 75 - 80.
    slib - rioolslib - waterstof - afvalwaterbehandeling - substraten - kinetica - sulfaten - anaërobe behandeling - sludges - sewage sludge - hydrogen - waste water treatment - substrates - kinetics - sulfates - anaerobic treatment
    Reported values for growth kinetic parameters show an order in competitivity of heterotrophic sulfate reducing bacteria>methanogens>homoacetogens for the substrate hydrogen. This order suggests that methanogens can succesfully compete with consortia of heterotrophic SRB and homoacetogens when H2/CO2 is present as sole substrate. However, we found in experiments using gas-lift reactors inoculated with anaerobic sludge and fed with H2/CO2 and sulfate, that heterotrophic sulfate reduction rapidly and completely outcompeted methanogenesis, whereas a low amount of acetate was formed. Thus, in disagreement with the above competitivity order, hydrogen is more readily consumed by homoacetogenesis than by methanogenesis, indicating that the competition is not kinetically determined. The superior settling velocity of sulfidogenic-acetogenic sludge compared to that of methanogenic sludge suggests that the former sludge is better retained, which can explain the predominance of sulfate reduction/homoacetogenesis over methanogenesis.
    Effect of high salinity on the fate of methanol during the start-up of thermophilic (55°C) sulfate reducing reactors
    Vallero, M.V.G. ; Hulshoff Pol, L.W. ; Lens, P.N.L. ; Lettinga, G. - \ 2002
    Water Science and Technology 45 (2002)10. - ISSN 0273-1223 - p. 121 - 126.
    anaërobe behandeling - afvalwaterbehandeling - methanol - reductie - natriumchloride - sulfaten - rioolafvalwater - slib - anaerobic treatment - waste water treatment - methanol - reduction - sodium chloride - sulfates - sewage effluent - sludges
    Two 6.5 L lab-scale upflow anaerobic sludge bed (UASB) reactors were operated at 55°C fed with methanol as the sole electron and carbon source and in excess of sulfate (COD/SO42- of 0.5) in order to investigate the effect of high wastewater salinity on the start-up period. The first reactor (UASB I) was operated without NaCl addition, while the second reactor (UASB II) was fed with 25 g.L-1 of NaCl in the first 13 days of operation. Successful start-up of UASB I was achieved, with full methanol conversion (100␎limination) to methane gas (methane production rate up to 3.66 gCOD.L-1.day-1). Despite the detection of sulfide from day 15 onwards in UASB I, methane was the main mineralization product when operating at an organic loading rate (OLR) of 5 gCOD.L-1.day-1 and a hydraulic retention time (HRT) of 10 hours. Sulfide and acetate started to be produced after salt omission from the influent in UASB II at day 13, with no detection of methane. Acetate was the main product when operating at an OLR of 10 gCOD.L-1.day-1 and HRT of 6.5 hours in both reactors. Apparently, the methane producing bacteria (MPB) are the trophic group most sensible to the NaCl shock.
    Differential responses of freshwater wetland soils to sulphate pollution
    Lamers, L.P.M. ; Dolle, G.E. ten; Berg, S.T.G. van den; Delft, S.P.J. van; Roelofs, J.G.M. - \ 2001
    Biogeochemistry 55 (2001)1. - ISSN 0168-2563 - p. 87 - 102.
    oppervlaktewater - eutrofiëring - sulfaten - wetlands - biogeochemie - bodemchemie - bodemverontreiniging - sulfaat - surface water - eutrophication - sulfates - wetlands
    Sulphate (SO42-) reduction rates are generally low in freshwater wetlands and are regulated by the scarce availability of the ion. Increased concentrations of this electron acceptor due to sulphur (S) pollution of groundwater and surface water may, however, lead to high sulphate reduction rates now regulated by the availability of appropriate electron donors. Due to variations in this availability, the response to S pollution (e.g. from surface water or groundwater) is expected to differ between soils. This hypothesis was tested in laboratory mesocosm experiments by comparing two wetland soil types with distinctly different humus profiles: a Hydromoder and a Rhizomull type. In the first type, expected to have a higher availability of degradable soilorganic matter (SOM), sulphate availability appeared to be rate limiting for sulphate reduction. In the Rhizomull soils, in contrast, the electron acceptor did not limit sulphate reduction rates at higher concentrations. These differences in response could not, however, be attributed to differences in the various SOM fractions or in SOM densities. Eutrophication and free sulphide accumulation, two major biogeochemical problems caused by sulphate pollution, occurred in both types. The absolute extent of phosphorus mobilisation was determined by the concentration of this element in the soil (C/P ratio), while the level of sulphide accumulation was governed by the concentration of dissolved iron in the pore water. It was therefore concluded that neither the humus profile nor the concentrations of different SOM fractions in the soils are reliable indicators for the sensitivity of wetland types to S pollution.
    Effect of nitrate on acetate degradation in a sulfidogenic staged reactor
    Lens, P.N.L. ; Sipma, J. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2000
    Water Research 34 (2000)1. - ISSN 0043-1354 - p. 31 - 42.
    afvalwaterbehandeling - denitrificatie - slib - acetaten (zouten) - sulfaten - reductie - waste water treatment - denitrification - sludges - acetates (salts) - sulfates - reduction
    Thermophilic sulfate reduction and methanogenesis with methanol in a high rate anaerobic reactor
    Weijma, J. ; Stams, A.J.M. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2000
    Biotechnology and Bioengineering 67 (2000)3. - ISSN 0006-3592 - p. 354 - 363.
    afvalwaterbehandeling - anaërobe behandeling - sulfaat - sulfaten - reductie - methanol - waste water treatment - anaerobic treatment - sulfate - sulfates - reduction - methanol
    Sulfate reduction outcompeted methanogenesis at 65°C and pH 7.5 in methanol and sulfate-fed expanded granular sludge bed reactors operated at hydraulic retention times (HRT) of 14 and 3.5 h, both under methanol-limiting and methanol-overloading conditions. After 100 and 50 days for the reactors operated at 14 and 3.5 h, respectively, sulfide production accounted for 80␘f the methanol-COD consumed by the sludge. The specific methanogenic activity on methanol of the sludge from a reactor operated at HRTs of down to 3.5 h for a period of 4 months gradually decreased from 0.83 gCOD ? gVSS-1 ? day-1 at the start to a value of less than 0.05 gCOD ? gVSS-1 ? day-1, showing that the relative number of methanogens decreased and eventually became very low. By contrast, the increase of the specific sulfidogenic activity of sludge from 0.22 gCOD ? gVSS-1 ? day-1 to a final value of 1.05 gCOD ? gVSS-1 ? day-1 showed that sulfate reducing bacteria were enriched. Methanol degradation by a methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanol was not important. H2/CO2 and formate, but not acetate, were degraded to methane in the presence of vancomycin. These results indicated that methanol degradation to methane occurs via the intermediates H2/CO2 and formate. The high and low specific methanogenic activity of sludge on H2/CO2 and formate, respectively, indicated that the former substrate probably acts as the main electron donor for the methanogens during methanol degradation. As sulfate reduction in the sludge was also strongly supported by hydrogen, competition between sulfate reducing bacteria and methanogens in the sludge seemed to be mainly for this substrate. Sulfate elimination rates of up to 15 gSO42-/L per day were achieved in the reactors. Biomass retention limited the sulfate elimination rate.
    De invloed van sulfaat en chloride op de fosfaatbeschikbaarheid in veenbodem, een bijdrage aan integraal waterbeheer.
    Beltman, B. ; Krift, T. van der - \ 1997
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 1 (1997). - ISSN 0166-8439 - p. 19 - 22.
    hoogveengronden - kanalen - chloor - hydrologie - veengronden - fosfor - rivieren - bodem - waterlopen - sulfaten - oppervlaktewater - moerasgronden - water - waterbeheer - waterverontreiniging - waterkwaliteit - watervoorziening - utrecht - bog soils - canals - chlorine - hydrology - peat soils - phosphorus - rivers - soil - streams - sulfates - surface water - swamp soils - water - water management - water pollution - water quality - water supply - utrecht
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