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.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Bioprocess engineering of sulfate reduction for environmental technology
    Lens, P.N.L. ; Meulepas, R.J.W. ; Sampaio, R. ; Vallero, M.V.G. ; Esposito, G. - \ 2007
    In: Microbial Sulfur Metabolism / Dahl, C., Friedrich, C.G., Berlin Heidelberg, Germany : Springer - ISBN 9783540726791 - p. 285 - 295.
    High rate sulfate reduction in a submerged anaerobic membrane bioreactor (SAMBaR) at high salinity
    Vallero, M.V.G. ; Lettinga, G. ; Lens, P.N.L. - \ 2005
    Journal of Membrane Science 253 (2005)1-2. - ISSN 0376-7388 - p. 217 - 232.
    methanogenic bacteria - thermophilic sulfate - waste-water - reducing bacterium - sulfite reduction - sp-nov - reactor - acetate - environments - degradation
    Sulfate reduction in salt rich wastewaters (50 g NaCl L¿1 and 1 g MgCl2·6H2O L¿1; conductivity 60¿70 mS cm¿1) was investigated in a 6 L submerged anaerobic membrane bioreactor (SAMBaR) and inoculated solely with the halotolerant sulfate reducing bacterium Desulfobacter halotolerans. The SAMBaR was fed with acetate and ethanol at organic loading rates up to 14 g COD L¿1 day¿1 in excess of sulfate (COD/SO42¿ of 0.5) and operated at pH 7.2 ± 0.2 and a hydraulic retention time (HRT) from 8 to 36 h. A sulfate reduction rate up to 6.6 g SO42¿ L¿1 day¿1 was achieved in the SAMBaR operating at a flux of 17.1 L m¿2 h¿1, which resulted in a HRT of 9 h including the backflow of permeate used for backflushing. The fairly constant very high specific sulfate reduction rate of 5.5 g SO42¿ g VSS¿1 day¿1 showed that the performance of the SAMBaR was limited by the low amount of biomass (0.85 g VSS L¿1) present in the reactor at the end of the experiment. It was shown that sulfate reducing submerged anaerobic membrane bioreactors can be operated over extended periods of time without chemical cleaning of the membranes at a certain fixed flux if this flux is substantially below the nominal critical flux determined experimentally (18¿21 L m¿2 h¿1). Intermittent operation as well as backflush of the membranes were shown to slow the fouling in the membranes. Frequent backflush (e.g. 1 min each 10 min) is the suggested operational strategy to minimize fouling in anaerobic MBRs.
    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.
    Thermophilic (55°C) conversion of methanol in methanogenic-UASB reactors: influence of sulphate on methanol degradation and competition
    Paulo, P.L. ; Vallero, M.V.G. ; Trevino, R.H.M. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
    Journal of Biotechnology 111 (2004)1. - ISSN 0168-1656 - p. 79 - 88.
    volatile fatty-acids - methanosarcina-barkeri - anaerobic-digestion - ethanol-production - bacteria - acetate - reduction - growth - carbon - fermentation
    Two upflow sludge bed reactors (UASB) were operated for 80 days at 55 degreesC with methanol as the substrate with an organic loading rate (OLR) of about 20 g COD l(-1) per day and a hydraulic retention time (HRT) of 10 h. One UASB was operated without sulphate addition (control reactor-R1) whereas the second was fed with sulphate at a COD:SO42- ratio of 10 (sulphate-fed reactor-R2), providing an influent sulphate concentration of 0.6 g l(-1). For both reactors, methanogenesis was the dominant process with no considerable accumulation of acetate. The methanol removal averaged 93% and 83% for R1 and R2, respectively, and total sulphate removal was achieved in the latter. The pathway of methanol conversion for both sludges was investigated by measuring the fate of carbon in the presence and absence of bicarbonate or specific inhibitors for a sludge sample collected at day 72. In both sludges, about 70% of the methanol was syntrophically converted to methane and/or sulphide, via the intermediate H-2/CO2. strong competition between methanogens and sulphidogens took place in the R2 sludge with half of the methanol-COD being used by methane-producing bacteria and the other half by sulphate-reducing bacteria. Acetate was not an important intermediate for both sludges, and played a slightly more important role for the sulphate-adapted sludge (R2), sustained by the higher amount of bicarbonate produced during sulphate-reduction. The pathway study indicates that, although acetate does not represent an important intermediate, the system is susceptible to its accumulation. (C) 2004 Elsevier B.V. All rights reserved.
    High-Rate Sulfate Reduction at High Salinity (up to 90 mS.cm-1) in Mesophilic UASB Reactors
    Vallero, M.V.G. ; Sipma, J. ; Lettinga, G. ; Lens, P.N.L. - \ 2004
    Biotechnology and Bioengineering 86 (2004)2. - ISSN 0006-3592 - p. 226 - 235.
    sulfaat - reductie - chemische reacties - zoutgehalte - geactiveerd slib - biodegradatie - acetaten - propionaten - ethanol - waterzuivering - sulfate - reduction - chemical reactions - salinity - activated sludge - biodegradation - acetates - propionates - ethanol - water treatment - desulfitobacterium-frappieri pcp-1 - anaerobic granular sludge - long-term competition - waste-water - methanogenic bacteria - biological treatment - reducing reactors - bed reactor - wastewaters - ammonia
    Sulfate reduction in salt-rich wastewaters using unadapted granular sludge was investigated in 0.9 L UASB reactors (pH 7.0 ± 0.2; hydraulic retention time from 8-14 h) fed with acetate, propionate, or ethanol at organic loading rates up to 10 gCOD.L-1.day-1 and in excess sulfate (COD/SO of 0.5). High-rate sulfate reduction rates (up to 3.7 gSO42-.L-1.day-1) were achieved at salinities exceeding 50 gNaCl.L-1 and 1 gMgCl2.L-1. Sulfate reduction proceeded at a salinity of up to 70 gNaCl.L-1 and 1 gMgCl2.L-1 (corresponding to a conductivity of about 85-90 mS.cm-1), although at lower rates compared to a conductivity of 60-70 mS.cm-1. Ethanol as well as propionate were suitable substrates for sulfate reduction, with acetate and sulfide as the end products. The successful high-rate treatment was due to the proliferation of a halotolerant incomplete oxidizing SRB population present in the unadapted inoculum sludge. Bioaugmentation of this sludge with the acetate oxidizing halotolerant SRB Desulfobacter halotolerans was unsuccessful, as the strain washed out from the UASB reactor without colonizing the UASB granules. © 2004 Wiley Periodicals, Inc.
    Sulfate reducing processes at extreme salinity and temperature. extending its application window
    Vallero, M.V.G. - \ 2003
    Wageningen University. Promotor(en): Gatze Lettinga, co-promotor(en): Piet Lens. - [S.l.] : S.n. - ISBN 9789058089090 - 214
    sulfaat reducerende bacteriën - zoutgehalte - anaërobe behandeling - bioreactoren - membranen - sulfate reducing bacteria - salinity - anaerobic treatment - bioreactors - membranes
    The characteristics of various sulfate-rich wastewaters, such as temperature, pH and salinity, are determined by the (industrial) process from which they originate, and can be far from the physiological optima of the sulfur cycle microorganisms. The main goal of the research described in this thesis was to investigate and develop high rate sulfate reducing wastewater treatment processes for the treatment of inorganic sulfate-rich wastewaters under extreme conditions, i.e. high temperature and high salinity. In this thesis, several simple organic bulk chemicals were tested as electron donor, viz. lower alcohols (methanol and ethanol) and volatile fatty acids (formate, acetate and propionate).

    With respect to the start-up of anaerobic sludge bed (UASB) reactors at high salinity or high temperature, the results obtained in this investigation indicate that the appearance of a targeted metabolic property (sulfate reduction at high salinity or at high temperature) is independent of the strategy for biomass acclimation (direct exposure vs. stepwise exposure).The stepwise adaptation of thermophilicsulfidogenic methanol degrading biomass to a highosmolarity environment, both at 55C or at 70C, likely does not occur in UASB reactors, as probably no methanol halotolerant thermophilic sulfate reducing bacteria (SRB) were present in the thermophilicinoculumsludge used in the investigations described in this thesis. Exposing the sludge directly to a very high salinity (50 g NaCl.L -1 ) stimulated the growth of amesophilic(30C) propionate- and ethanol-utilizinghalotolerantSRB population, which supported high rate sulfate reduction (up to 3.6 g SO 42- .L -1 .day -1 ) in a UASB reactor. The start-up ofthermophilic(55 to 65C) and extremethermophilicC or higher) anaerobic bioreactors inoculated withmesophilicsludgesat the targeted temperature proceeded fast and stable, as it provoked the rapid selection of (extreme)thermophiles. Therefore, the key for the successful treatment of high salinity or hot wastewaters is to invest enough time for the growth of the targeted microorganism in the biomass.

    The results of this investigation show that the competition between SRB, methane producingarchaeaandacetogenicbacteria for substrate is highly dependent of the type of substrate and operational conditions imposed to the bioreactor. This thesis describes a situation where the production of acetate and methane was completely suppressed in methanol-fed sulfate reducing UASB reactors operated at 70C. As a result, for the first time a fully sulfate reducing granular sludge has been cultivated in a methanol-fedthermophilicsulfate reducing reactor (with sulfate reduction rates as high as 14.4 g SO 42- .L -1 .day -1 ), provided that an operational temperature of 70C is kept. The production of methane can be easily suppressed inthermophilicmethanol fed reactors, either by running the reactor at temperatures equal or higher than 65C or by exposing 55C operated reactors to a short (2 days) temperature (65 - 70C) shock.Methanogenesiscan also be easily suppressed inmesophilicpropionate- and ethanol-fed reactors, provided high salinity conditions prevail (e.g. above 50 mS.cm -1 ). It seems, however, that the production of acetate, with the exception of methanol-fed reactors operated at 70C, is unavoidable both inthermophilicandmesophilicreactors.

    This thesis also describes the use of specialized microorganisms, the halophilicDesulfobacterhalotolerans , in bioreactors for the treatment of saline sulfate-rich wastewaters. Very high specific sulfate reduction rates (up to 6.6 g SO 42- .gVSS -1 .day -1 ) can be obtained in completely mixed tank reactors where the biomass grows in suspension and can be efficiently retained by membranes which are submerged in the reactor system. This investigation showed that anaerobic membrane bioreactors can be operated over extended periods of time at a fixed flux, if this flux is substantially below the nominal critical flux determined experimentally (18-21 L.m -2 .h -1 ). Chemical cleaning of the membranes will be required only at about 106 days, as long a low constant flux is imposed (4.7 L.m -2 .h .1 ) and intermittentbackflush(e.g. 1 minute each 10 minutes) is adopted as operational strategy.
    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.
    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.
    Biotechnological treatment of sulfate containing wastewaters
    Vallero, M.V.G. ; Sipma, J. ; Annachhatre, A. ; Lens, P.N.L. ; Hulshoff Pol, L.W. - \ 2003
    In: Recent Advances in Marine Biotechnology. Vol. 8. Bioremedation / Fingerman, M., Nagabhushanam, R., Enfield : Science Publishers - ISBN 9781578082452 - p. 233 - 268.
    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.
    Effect of sulfate on methanol degradation in thermophilic (55 oC) methanogenic UASB reactors
    Vallero, M.V.G. ; Lens, P.N.L. ; Paulo, P.L. ; Trevino, R.H.M. ; Lettinga, G. - \ 2003
    Enzyme and Microbial Technology 32 (2003)6. - ISSN 0141-0229 - p. 676 - 687.
    slib - anaërobe behandeling - methanol - zwavel - retentie - afvalwaterbehandeling - rioolafvalwater - sludges - anaerobic treatment - methanol - sulfur - retention - waste water treatment - sewage effluent - volatile fatty-acid - anaerobic hybrid reactor - granular sludge reactor - waste-water - ethanol degradation - reduction - digestion - velocity - hydrogen - pulp
    A thermophilic (55 degreesC) lab-scale (0.921) methanol-fed upflow anaerobic sludge bed (UASB) reactor (pH 7.0 and hydraulic retention time (HRT) of 7.5 h) was operated at chemical oxygen demand (COD) to sulfate (SO42-) ratios of 10, 5 and 0.5 during 155 days to evaluate the effects of the presence of sulfate on conversion rates, metabolic shifts and possible process disturbances
    A thermophilic (55 degreesC) lab-scale (0.921) methanol-fed upflow anaerobic sludge bed (UASB) reactor (pH 7.0 and hydraulic retention time (HRT) of 7.5 h) was operated at chemical oxygen demand (COD) to sulfate (SO42-) ratios of 10, 5 and 0.5 during 155 days to evaluate the effects of the presence of sulfate on conversion rates, metabolic shifts and possible process disturbances. Methanol was completely removed when operating at an organic loading rate of 20 g COD l(-1) day(-1) at all COD/SO42- ratios tested. At COD/SO42- ratios of 10 and 5. methanol was converted both via sulfate reduction (up to 13% when operating at a COD/SO42- of 5) and methanogenesis (85%). However, when operating at a COD/sulfate ratio of 0.5 (12 g SO42- l(-1)), the sulfate reduction efficiency strongly deteriorated, due to improper immobilization of sulfate reducing bacteria (SRB) in the sludge bed and the presence of relatively high sodium concentrations (about 6 g Na+ l(-1)) originating from supplying sulfate as its sodium salt. Complete sulfate reduction was achieved when operating at a COD/SO42- ratio of 10 (0.6 g SO42- l(-1)) and 5 (1.2 g SO42- l(-1)), corresponding to sulfate removal rates of 2 and 4 g SO42- l(-1) day(-1), respectively. Activity tests showed that methanol was syntrophically converted via H-2/CO2 by homoacetogenic bacteria, in combination with either sulfate reducing bacteria or methane producing archaea. (C) 2003 Elsevier Science Inc. All rights reserved.
    Dissimilatory sulfate reduction in environmental biotechnology
    Lens, P.N.L. ; Vallero, M.V.G. ; Esposito, G. ; Zandvoort, M.H. - \ 2002
    Critical Reviews in Environmental Science and Technology 1 (2002)4. - ISSN 1064-3389 - p. 311 - 325.
    Environmental protection in industry for sustainable development
    Lens, P.N.L. ; Vallero, M.V.G. ; Lettinga, G. - \ 2002
    In: Proceedings of Industrial wastewater recovery and reuse, Cranfield, UK, 2002 / S. Judd. - Cranfield, UK : The school of water sciences, Cranfield University, 2002 - p. 11 - 19.
    Environmental protection in industry for sustainable development
    Lens, P.N.L. ; Vallero, M.V.G. ; Gonzalez-Gil, G. ; Rebac, S. ; Lettinga, G. - \ 2002
    In: Water Recycling and Resource Recovery in Industry / Lens, P.N.L., Hulshoff Pol, L.W., Wilderer, P., Asano, T., London, UK : IWA Publishing - ISBN 9781843390053 - p. 53 - 65.
    The use of compatible solutes as osmoprotectants to overcome salinity stress in thermophilic (55° C) methanol-fed sulfate reducing granular sludges
    Vallero, M.V.G. ; Lettinga, G. ; Lens, P.N.L. - \ 2002
    In: Proceedings of the 7th Latin American symposium on anaerobic digestion, Mexico, 2002. - [S.l.] : [s.n.], 2002 - p. 351 - 358.
    The use of salt-tolerant microorganisms in thermophilic (55°C) methanol-fed sulfate reducing granular sludge reactors
    Vallero, M.V.G. ; Lens, P.N.L. ; Hulshoff Pol, L.W. ; Lettinga, G. - \ 2002
    In: EURO Summerschool The Sulfur Cycle in Environmental Biotechnology, Wageningen, The Netherlands, 2002 / Lens, P.N.L., Vallero, M.V.G., Hulshoff Pol, L.W. (eds.). - Wageningen, The Netherlands : Sub-dept. of Environmental Technology, Wageningen University, 2002 - p. 1 - 1.
    Comparison of leaching of heavy metal mobilization from dredged sediment using column and batch tests
    Popenda, A. ; Malina, G. ; Grotenhuis, J.T.C. - \ 2002
    In: EURO Summerschool The Sulfur Cycle in Environmental Biotechnology, Wageningen, The Netherlands, 2002 / Lens, P.N.L., Vallero, M.V.G., Hulshoff Pol, L.W., Wageningen, The Netherlands : Sub-dept. of Environmental Technology - p. 1 - 1.
    Effects of trace metals addition on volatile fatty acid conversions in anaerobic granular sludge reactors
    Osuna, M.B. ; Zandvoort, M.H. ; Iza, J.M. ; Lettinga, G. ; Lens, P.N.L. - \ 2002
    In: EURO Summerschool The Sulfur Cycle in Environmental Biotechnology, Wageningen, The Netherlands, 2002 / Lens, P.N.L., Vallero, M.V.G., Hulshoff Pol, L.W., Wageningen, The Netherlands : Sub-dept. of Environmental Technology - p. 1 - 1.
    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.
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