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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    Quantitative and Orthogonal Formation and Reactivity of SuFEx Platforms
    Gahtory, Digvijay ; Sen, Rickdeb ; Pujari, Sidharam ; Li, Suhua ; Zheng, Qinheng ; Moses, John E. ; Sharpless, K.B. ; Zuilhof, Han - \ 2018
    Chemistry-A European Journal 24 (2018)41. - ISSN 0947-6539 - p. 10550 - 10556.
    click chemistry - fluorine - sulfur - surface chemistry - surface modification

    The constraints of minute reactant amounts and the impossibility to remove any undesired surface-bound products during monolayer functionalization of a surface necessitate the selection of efficient, modular and orthogonal reactions that lead to quantitative conversions. Herein, we explore the character of sulfur–fluoride exchange (SuFEx) reactions on a surface, and explore the applicability for quantitative and orthogonal surface functionalization. To this end, we demonstrate the use of ethenesulfonyl fluoride (ESF) as an efficient SuFEx linker for creating “SuFEx-able” monolayer surfaces, enabling three distinct approaches to utilize SuFEx chemistry on a surface. The first approach relies on a di-SuFEx loading allowing dual functionalization with a nucleophile, while the two latter approaches focus on dual (CuAAC–SuFEx/SPOCQ–SuFEx) click platforms. The resultant strategies allow facile attachment of two different substrates sequentially on the same platform. Along the way we also demonstrate the Michael addition of ethenesulfonyl fluoride to be a quantitative surface-bound reaction, indicating significant promise in materials science for this reaction.

    Physiology and application of sulfur-reducing microorganisms from acidic environments
    Florentino, Anna Patrícya - \ 2017
    Wageningen University. Promotor(en): Fons Stams, co-promotor(en): Irene Sanchez Andrea; Jan Weijma. - Wageningen : Wageningen University - ISBN 9789463430975 - 264
    bacteria - desulfurella - metabolism - sulfur - reduction - genome analysis - proteomes - bacteriën - desulfurella - metabolisme - zwavel - reductie - genoomanalyse - proteomen

    Sulfur cycle is one of the main geochemical cycles on Earth. Oxidation and reduction reactions of sulfur are mostly biotic and performed by microorganisms. In anaerobic conditions – marine and some freshwater systems, dissimilatory sulfur- and sulfate-reducing bacteria and archaea are key players in the decomposition of organic carbon releasing sulfide as the product of their metabolism. Sulfide can then be used as terminal reductant by anoxygenic photosynthetic microorganisms or it can be used as electron donor for aerobic or nitrate-reducing bacteria, etc.

    One particular case of the sulfur cycle is the naturally occurring oxidation of metallic sulfide-ores, which produce sulfur-rich waters with low pH and high heavy metals content. Extremophilic sulfur-reducing microorganisms are of scientific and technological interest. They are abundant in natural conditions in extreme environments, so they are environmentally relevant. Although hydrogen sulfide is corrosive and odorous, its production can be beneficial for industrial activities such as the precipitation and recovery of heavy metals. Therefore, sulfur reducers have also potential for extending the range of operating conditions of metal precipitation. This thesis describes the isolation and characterization of acidotolerant sulfur-reducing bacteria, providing a first understanding on their metabolism of sulfur compounds and insights on the beneficial microbial interactions for biotechnological purposes.

    In Chapter 2, the ecology and physiology of sulfur-reducing prokaryotes is investigated. The ability of sulfur reduction is wide-spread phylogenetically over the microbial tree of life, found in more than 70 genera. Elemental sulfur reduction can occur via direct cell attachment to the solid substrate or with polysulfide as an intermediate. At least four different enzymes are described to be involved in sulfur reduction pathways, and these enzymes were also detected in several microorganisms that are potential sulfur reducers, but were not reported as such in literature so far. The ecological distribution of sulfur respiration seems to be more widespread at high temperatures with neutral pH values. However, some sulfur reducers can grow at pH as low as 1 and the strategies adopted by microorganisms to face high proton concentrations in the environment were commented in this chapter. The sulfide produced from sulfur reduction can be used to selectively precipitate metals by varying the pH values from 2 to 7, depending on the target metal. Economic calculations were presented to show that sulfur reduction is more advantageous then sulfate reduction due to the cost savings of the electron donor needed. Therefore, acidophilic sulfur reducers are of particular interest for application in selective precipitation and recovery of heavy metals from metalliferous waste streams and the suitable technologies for that purpose are also discussed.

    Enrichments for sulfur reducers with various electron donors at low pH and mesophilic conditions were performed from sediments of the acidic Tinto river (Spain). A solid-media with colloidal sulfur was developed to facilitate the isolation of true elemental sulfur reducers at low pH. This strategy resulted in the isolation of a sulfur-reducing bacterium, strain TR1, belonging to the Desulfurella genus. The enrichment and isolation procedure were described in Chapter 3. The growth and activity of the isolate was tested at different pH values, temperature conditions, utilization of electron donors, and growth in the presence of heavy metals in solution. The isolate showed tolerance to metals, and growth in a broad temperature and pH, revealing its feasibility to precipitate and recover heavy metals from acidic wastewater and mining water, without the need to neutralize the water before treatment. In Chapter 4, the morphological, biochemical and physiological characterization of the isolate is provided, for which the name Desulfurella amilsii TR1 sp. nov. was proposed. D. amilsii is affiliated to the Deltaproteobacteria class showing 97% of 16S rRNA gene identity to the four species described in the Desulfurella genus. In the presence of elemental sulfur, D. amilsii utilized acetate, formate, lactate, pyruvate, stearate, arginine and H2/CO2 as substrates, completely oxidizing them to H2S and CO2. Besides elemental sulfur, thiosulfate was used as an electron acceptor and the isolate also grew in the absence of external electron donor, by disproportionation of elemental sulfur into sulfide and sulfate.

    The draft genome sequence of Desulfurella amilsii TR1 and a comparative genomic analysis with the members of Desulfurellaceae family are reported in Chapter 5. Based on average nucleotide identity and in silico DNA hybridization values, D. multipotens and D. acetivorans were revealed to belong to the same species. Reclassification was therefore suggested. Regarding sulfur metabolism, the analysed genomes encode different sulfur-reducing enzymes per genus. Hippea species encode polysulfide reductase and a sulfide dehydrogenase. The analysed genomes of Desulfurella especies do not possess the polysulfide reductase but possess the sulfide dehydrogenase. D. amilsii is the only member of the family encoding sulfur reductase. Since D. amilsii is able to grow at the lowest pH value, this enzyme was suggested to play a role in sulfur reduction when the microorganism grows in acidic conditions. Genes encoding resistance to acidic conditions were reported for all Desulfurellaceae members, countering physiological tests that showed ability to grow at low pH only for D. amilsii and D. acetivorans. Sulfur respiration by D. amilsii was studied in more detail in Chapter 6, in which the requirement for cell-sulfur interaction at acidic (pH 3.5) and circumneutral (pH 6.5) conditions was evaluated. D. amilsii was shown to benefit from contact with the insoluble substrate, as activity and number of cells decreased when sulfur was sequestered from the medium in dialysis bags of 6-8 kDa pore size. Besides, the abundance of enzymes possibly involved in sulfur respiration, acid resistance and chemolithotrophic growth were investigated by proteomics. Sulfur reductases were not detected in the dataset, but the limitations of the method might leave membrane-bound proteins underrepresented in the study. Different rhodanese-like proteins were detected in high abundance at low and neutral pH, while sulfide dehydrogenase seems to function as a ferredoxin:NADP oxidoreductase. We suggest that the sulfurtransferases might play a key role in sulfur/polysulfide reduction in D. amilsii. Proteomic data also showed that genes involved in acid resistance are constitutively expressed in this microorganism. Some proteins were exclusively detected at low pH, but with very few overlapping with proteins reported to be involved in acid resistance. Moreover, analysis of the proteome revealed the involvement of the hydrogenase HydABC for oxidation of hydrogen during chemolitotrophic growth, as well as the complete pathway for CO2 fixation via the reductive TCA cycle.

    More aspects of the sulfur metabolism by D. amilsii were investigated in Chapter 7. Cultures grown on acetate with sulfur or thiosulfate as electron acceptor and cultures grown by disproportionation of elemental sulfur, all at pH 6.5, had their proteomes compared. Rhodanese-like sulfurtransferases were abundant in all the analyzed conditions, with specific differences in the sequences. In sulfur respiration and disproportionation, sulfurtransferases were the only sulfur enzymes detected and so, they are likely to play a central role in the process. The respiration of thiosulfate is likely to happen via a thiosulfate reductase and a dissimilatory sulfite reductase, highly abundant in this specific condition. Analysis on the heterotrophic cultures revealed the ability of D. amilsii to activate acetate to acetyl-CoA via the acetyl-CoA synthetase enzyme and its oxidation via the TCA cycle being this the first report of acetate activation happening via acetyl-CoA synthetase in sulfur-reducing bacteria.

    The isolation and characterization of another acidotolerant sulfur respirer, Lucifera butyrica strain ALE, and its growth in co-culture with D. amilsii were described in Chapter 8. L. butyrica was shown to use a wide range of substrate, such as glucose, lactose, ethanol, glycerol glycogen, peptone, etc. When growing on glycerol, a cheap substrate, by fermentation or by respiration of elemental sulfur, L. butyrica produced acetate, ethanol and 1,3-propanediol as major products. Elemental sulfur reduction by this bacterium, however, was not efficient and led to the production of maximum 2.5 mM of sulfide. When L. butyrica grew in a co-culture with D. amilsii, the acetate produced by the first was consumed by the latter and the production of sulfide was boosted in the culture. As D. amilsii is not able to degrade glycerol, the co-culture represents a strategy to broaden the applicability of sulfur reduction at low pH with different sources of electron donors.

    30 vragen en antwoorden over zwavel
    Schils, René - \ 2016
    Wageningen : Alterra, Wageningen-UR - 68
    zwavel - zwavelmeststoffen - bemesting - uitspoelen - depositie - sulfur - sulfur fertilizers - fertilizer application - leaching - deposition
    Het Ministerie van Economische Zaken heeft de Commissie van Deskundigen Meststoffenwet gevraagd de belangrijkste vragen en antwoorden over zwavel op toegankelijke wijze te beschrijven. Deze publicatie brengt het onderwerp zwavel voor het voetlicht.
    Desulfosporosinus acididurans sp. nov.: an acidophilic sulfate-reducing bacterium isolated from acidic sediments
    Sanchez Andrea, I. ; Stams, A.J.M. ; Hedrich, S. ; Nancucheo, I. ; Johnson, D.B. - \ 2015
    Extremophiles 19 (2015)1. - ISSN 1431-0651 - p. 39 - 47.
    water lake-sediments - mine drainage - low ph - gen. nov. - microbial communities - transition-metals - reduction - sulfidogenesis - sulfur - bioremediation
    Three strains of sulfate-reducing bacteria (M1T, D, and E) were isolated from acidic sediments (White river and Tinto river) and characterized phylogenetically and physiologically. All three strains were obligately anaerobic, mesophilic, spore-forming straight rods, stained Gram-negative and displayed variable motility during active growth. The pH range for growth was 3.8–7.0, with an optimum at pH 5.5. The temperature range for growth was 15–40 °C, with an optimum at 30 °C. Strains M1T, D, and E used a wide range of electron donors and acceptors, with certain variability within the different strains. The nominated type strain (M1T) used ferric iron, nitrate, sulfate, elemental sulfur, and thiosulfate (but not arsenate, sulfite, or fumarate) as electron acceptors, and organic acids (formate, lactate, butyrate, fumarate, malate, and pyruvate), alcohols (glycerol, methanol, and ethanol), yeast extract, and sugars (xylose, glucose, and fructose) as electron donors. It also fermented some substrates such as pyruvate and formate. Strain M1T tolerated up to 50 mM ferrous iron and 10 mM aluminum, but was inhibited by 1 mM copper. On the basis of phenotypic, phylogenetic, and genetic characteristics, strains M1T, D, and E represent a novel species within the genus Desulfosporosinus, for which the name Desulfosporosinus acididurans sp. nov. is proposed. The type strain is M1T (=DSM 27692T = JCM 19471T). Strain M1T was the first acidophilic SRB isolated, and it is the third described species of acidophilic SRB besides Desulfosporosinus acidiphilus and Thermodesulfobium narugense.
    Zwavelvoorziening op biologische veebedrijven
    Beeckman, A. ; Eekeren, N.J.M. van; Govaerts, W. ; Smolders, E.A.A. - \ 2014
    BioKennis bericht Zuivel & rundvlees (2014)30.
    zwavel - mineraaltekorten - biologische landbouw - eiwit - zwavelmeststoffen - melkveehouderij - vleesvee - schapen - geiten - diergezondheid - sulfur - mineral deficiencies - organic farming - protein - sulfur fertilizers - dairy farming - beef cattle - sheep - goats - animal health
    Door luchtverontreiniging kwam zwavel jarenlang gratis uit de lucht. Nu dit milieu­-probleem is opgelost krijgt de landbouw steeds meer te maken met zwaveltekorten. Zwavel is een essentieel element voor de vorming van verschillende aminozuren (o.a. methionine en cysteine) en daarmee van eiwit. Eiwitvorming is zowel belangrijk voor gewas als dierproductie dus zwaveltekorten komen bij beide voor.
    Metabolomics in melon: A new opportunity for aroma analysis
    Allwood, J.W. ; Cheung, W.W.L. ; Xu, Y. ; Mumm, R. ; Vos, C.H. de; Deborde, C. ; Biais, B. ; Maucourt, M. ; Berger, Y. ; Schaffer, A. ; Rolin, D. ; Moing, A. ; Hall, R.D. ; Goodacre, R. - \ 2014
    Phytochemistry 99 (2014). - ISSN 0031-9422 - p. 61 - 72.
    charentais cantaloupe melons - volatile organic-compounds - oxidase antisense gene - cucumis-melo - gas-chromatography - flavor compounds - cv makdimon - fruit - constituents - sulfur
    Cucumis melo fruit is highly valued for its sweet and refreshing flesh, however the flavour and value are also highly influenced by aroma as dictated by volatile organic compounds (VOCs). A simple and robust method of sampling VOCs on polydimethylsiloxane (PDMS) has been developed. Contrasting cultivars of C. melo subspecies melo were investigated at commercial maturity: three cultivars of var. Cantalupensis group Charentais (cv. Cézanne, Escrito, and Dalton) known to exhibit differences in ripening behaviour and shelf-life, as well as one cultivar of var. Cantalupensis group Ha’Ogan (cv. Noy Yisre’el) and one non-climacteric cultivar of var. Inodorus (cv. Tam Dew). The melon cultivar selection was based upon fruits exhibiting clear differences (cv. Noy Yisre’el and Tam Dew) and similarities (cv. Cézanne, Escrito, and Dalton) in flavour. In total, 58 VOCs were detected by thermal desorption (TD)-GC–MS which permitted the discrimination of each cultivar via Principal component analysis (PCA). PCA indicated a reduction in VOCs in the non-climacteric cv. Tam Dew compared to the four Cantalupensis cultivars. Within the group Charentais melons, the differences between the short, mid and long shelf-life cultivars were considerable. 1H NMR analysis led to the quantification of 12 core amino acids, their levels were 3–10-fold greater in the Charentais melons, although they were reduced in the highly fragrant cv. Cézanne, indicating their role as VOC precursors. This study along with comparisons to more traditional labour intensive solid phase micro-extraction (SPME) GC–MS VOC profiling data has indicated that the high-throughput PDMS method is of great potential for the assessment of melon aroma and quality.
    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 (
    Sulphate reduction and calcite precipitation in relation to internal eutrophication of groundwater fed alkaline fens
    Cirkel, D.G. ; Beek, C.G.E.M. van; Witte, J.P.M. ; Zee, S.E.A.T.M. van der - \ 2014
    Biogeochemistry 117 (2014)2-3. - ISSN 0168-2563 - p. 375 - 393.
    organic-matter - calcareous fens - phosphate - sulfur - soils - water - netherlands - sediments - adsorption - peatland
    Although in Europe atmospheric deposition of sulphur has decreased considerably over the last decades, groundwater pollution by sulphate may still continue due to pyrite oxidation in the soil as a result of excessive fertilisation. Inflowing groundwater rich in sulphate can change biogeochemical cycling in nutrient-poor wetland ecosystems. Incoming sulphate loads may induce internal eutrophication as well as the accumulation of dissolved sulphide, which is phytotoxic. We, however, argue that upwelling sulphate rich groundwater may also promote the conservation of rare and threatened alkaline fens, since excessive fertilisation and pyrite oxidation also produces acidity, which invokes calcite dissolution, and increased alkalinity and hardness (Ca2+ + Mg2+) of the inflowing groundwater. Our observations in a very species-rich wetland nature reserve show that sulphate is reduced and effectively precipitates as iron sulphides when this calcareous and sulphate rich groundwater flows upward through the organic soil of the investigated nature reserve. Furthermore, we show that sulphate reduction coincides with an increase in alkalinity production, which in our case results in active calcite precipitation in the soil. In spite of the occurring sulphate reduction we found no evidence for internal eutrophication. Extremely low phosphorous concentration in the pore water could be attributed to a high C:P ratio of soil organic matter and co-precipitation with calcite. Our study shows that seepage dependent alkaline fen ecosystems can be remarkably resilient to fertilisation and pyrite oxidation induced groundwater quality changes.
    Biological treatment of sulfidic spent caustics under haloalkaline conditions using soda lake bacteria
    Graaff, C.M. de - \ 2012
    Wageningen University. Promotor(en): Albert Janssen; G. Muyzer, co-promotor(en): M.F.M. Bijmans. - S.l. : s.n. - ISBN 9789461734457 - 132
    alkaliteit - thiobacillus denitrificans - thiobacillus - microbiële afbraak - biologische behandeling - afvalverwerking - zwavel - alkalinity - thiobacillus denitrificans - thiobacillus - microbial degradation - biological treatment - waste treatment - sulfur

    In this thesis, the development of a newbiotechnological process for the treatment of undiluted sulfidic spent caustics (SSC’s) using soda lake bacteria is described. SSC’s are waste solutions that are formed in the oil and gas industry due to the caustic (NaOH) scrubbing of hydrocarbon streams for the removal of sulfur compounds.Without treatment, SSC’s may impose serious environmental problems because of their alkalinity (pH>12), salinity (Na+ 5-12 wt%) and high sulfide (HS- and S2-) levels. Depending on the hydrocarbon stream that is treated, SSC’s may also contain organic sulfur compounds and monoaromatic hydrocarbons. Biological treatment of undiluted SSC’s would be a cheaper and safer alternative to the currently applied physico-chemical treatment methods (e.g., wet air oxidation or deep well disposal) since no additional chemicals are needed and the process works at ambient pressure and temperature conditions.

    In chapter 2 the biological treatment of refinery SSC’s is described in continuously fed systems under haloalkaline conditions (i.e. pH 9.5; Na+ 0.8 M). The experiments were performed in gas-lift bioreactors operated under aerobic conditions at 35 oC. Sulfide removal was complete up to 27 mmol L-1 day-1 by conversion to sulfate (SO42-). The sulfide conversion was accomplished by haloalkaliphilic sulfide-oxidizing bacteria (HA-SOB) belonging to the genus Thioalkalivibrio. Members of the this genus are extremophiles that are able to oxidize sulfide under a broad range of haloalkaline conditions (0.3 - 4.3 M Na+ and up to pH 10.6). In this chapter, it wasalso shown that benzene, at influent concentrations ranging from 100 to 600 µM, was removed by 93% due to air-stripping and biodegradation. Microbial community analysis revealed the presence of haloalkaliphilic heterotrophic bacteria belonging to the genera Marinobacter, Halomonas andIdiomarina which might have been involved in the observed benzene removal.

    Sour gases and SSC’s may also contain elevated amounts of methanethiol (MT; CH3SH). Hence, knowledge on the potential toxic effects of these type of compounds on the performance of this biotechnological process is required. Under sulfur (S0) forming conditions, MT reacts with biologically produced S0 particles resulting in a mixture of inorganic polysulfides (Sx2-), dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS). Respiration experiments with HA-SOB (Thioalkalivibrio mix) show in chapter 3 that biological oxidation of sulfide to S0 is inhibited by 50% (Ki value) at 0.05 mM MT. The measured Ki values for DMDS and DMTS were 1.5 and 1.0 mM, respectively.As DMDS and DMTS are products from the reaction between MT and S0, this reaction results in a partial detoxification of MT in a S0-producing bioreactor.The results from the respiration experiments as shown in chapter 3 indicate that the application of the biotechnological process for the treatment of H2S and MT containing gases and SSC’s is feasible as long as MT, DMDS and DMTS do not accumulate in the bioreactor.Accumulation of MT can be prevented by auto-oxidation of MT to DMDS, by the reaction between MT and biosulfur particles or biodegradation.

    Chapter 4 discusses the biological treatment of synthetically prepared SSC’s containing both sulfide and DMDS.Continuously fed gas-lift bioreactor experiments showed that biological sulfide oxidation (4-10 mmol L-1 day-1) is possible in the presence of low concentrations of DMDSunder haloalkaline conditions (i.e., pH 9.5; Na+ 0.8 M).Sulfide was completely oxidized to SO42- by members of the genus Thioalkalivibrio (closely related to Thioalkalivibriosp.K90-mix). It was also shown that severe inhibition of thebiological sulfide oxidation capacity and process deterioration occurs at DMDS effluent concentrations between 0.1 and 0.9 mM. The measured DMDS removal efficiency amounted up to 40-70% (0.05-0.37 DMDS-S L-1 day-1), of which 25% could be attributed to air stripping. It is yet unclear what other processes contributed to the total DMDS removal and it can only be speculated that the remainder was removed by biological conversion and/or adsorption. Results from respiration experiments presented in chapter 4 reveal that pure cultures of HA-SOB (Thioalkalivibrio sp.K90-mix and Thioalkalivibrio sulfidophilus) as well as biosludge taken from a full-scale installation for H2S removal (Thiopaq) are more severely inhibited by MT than DMDS. Furthermore, the Ki values for DMDS and MT were lower for Thioalkalivibrio sp. K90-mix and Thioalkalivibrio sulfidophilus compared to Thiopaq sludge. From bioreactor and respiration experiments it follows that, to ensure stable process conditions, MT and DMDS concentrations need to be below 0.02 and 0.1 mM, respectively. This clearly demonstrates that treating SSC’s with elevated MT and DMDS concentrations will easily inhibit the sulfide oxidation capacity of the process. Although auto-oxidation of MT will result in (partial) detoxification due to the formation of DMDS, the effluent levels still need to be kept very low. Successful biological treatment of MT and DMDS containing SSC’s will depend on the biological degradation of these compounds. When rapid biodegradation of organic VSC’s can be achieved, the concentrations in the reactor will remain below the critical levels.

    Chapter 5 shows that the application of a newly developed 2-step process for the biological treatments of SSC’s using HA-SOB allows significantly higher sulfide removal efficiencies compared to a 1-step process. The detoxification of sulfide by the abiotic oxidation to thiosulfate (S2O32-) in the first chemical oxidation step and the subsequent complete biological oxidation in the second step allowed total-S loading rates up to 33 mmol L-1 day-1. Experiments with synthetically prepared solutions were performed in a continuously fed system consisting of two gas-lift reactors in series. These reactors were operated at haloalkaline (pH 9.5; Na+ 0.8M) and aerobic conditions at 35oC.Mathematical modelling of the 2-step process shows that under the prevailing conditions an optimal reactor configuration consists of 40% ‘abiotic’ and 60% ‘biological’ volume, whilst the total reactor volume is 22% smaller than for the 1-step process. The major advantages of a 2-step process are the improved anticipation to shock loads of sulfideand lower investment and operational costs due to downsizing of the total reactor volume.

    Further research regarding the biological treatment of SSC’s may involve the potential of heterotrophic soda lake bacteria for the degradation of organic VSC’s as well as the mechanisms of toxicity of these compounds.

    Wat te doen als curatieve middelen wegvallen
    Jong, P.F. de; Bruine, J.A. de - \ 2012
    De Fruitteelt 102 (2012)7. - ISSN 0016-2302 - p. 14 - 15.
    chemische bestrijding - fungiciden - zwavel - fruitteelt - dosering - timing - venturia inaequalis - schimmelbestrijding - plantenziekteverwekkende schimmels - gewasbescherming - chemical control - fungicides - sulfur - fruit growing - dosage - timing - venturia inaequalis - fungus control - plant pathogenic fungi - plant protection
    Resistentie is een risicofactor bij het gebruik van de huidige, curatieve middelen tegen schurft. Is er een alternatief als deze middelen niet meer werken? Daarom onderzocht PPO strategieën om schurft effectief te bestrijden zonder gebruik te maken van resistentiegevoelige middelen. Stopspray-toediening van zwavel, eventueel in combinatie met een niet-resistentiegevoelig curatief middel, kan een alternatief zijn.
    Zwavel in de rwzi: Autotrofe denitrificatie en zwavelterugwinning als zuiveringstechniek voor rwzi’s - een haalbaarheidsstudie
    Dekker, A. ; Menkveld, H.W.H. ; Hermans, P.G.B. ; Panjer, M.A.C. ; Lam, G.P. 't - \ 2011
    Stowa (Rapport / STOWA 2011-21) - ISBN 9789057735301 - 80
    rioolwaterzuivering - denitrificatie - zwavel - slib - sewage treatment - denitrification - sulfur - sludges
    Aanvullende nitraatverwijdering vraagt om extra CZV of een efficiënter gebruik van het beschikbare CZV. De inzet van autotrofe denitrificatie maakt dit mogelijk. Bij autotrofe denitrificatie kan zwavel als elektrondonor worden gebruikt. Voor aanvullende heterotrofe denitrificatie is het gangbaar om een externe C-bron zoals methanol te doseren. De nadelen hiervan zijn veiligheidsrisico’s en kosten. Voor zwavel gelden deze nadelen minder. Ook is zwavel, zeker wanneer een interne stroom kan worden gebruikt, duurzamer. Dit onderzoek is uitgevoerd om de zwavelstromen op een rwzi in kaart te brengen en de haalbaarheid van autotrofe denitrificatie in de rwzi te verkennen. Daarnaast is onderzocht of het zwavelgehalte in slib en daarmee de aan zwavel gerelateerde slibverwerkingskosten kunnen worden verlaagd.
    Processing of Arsenopyritic Gold Concentrates by Partial Bio-Oxidation Followed by Bioreduction
    Hol, A. ; Weijden, R.D. van der; Weert, G. van; Kondos, P. ; Buisman, C.J.N. - \ 2011
    Environmental Science and Technology 45 (2011)15. - ISSN 0013-936X - p. 6316 - 6321.
    sulfur - dissolution - bioreactor - mechanisms - reduction - oxidation - minerals - progress - removal - iron
    Gold is commonly liberated from sulfide minerals by chemical and biological oxidation. Although these technologies are successful, they are costly and produce acidic waste streams. Removal of mineral-sulfur to overcome the mineralogical barrier could also be done by bioreduction, producing hydrogen sulfide (H2S). To make the sulfur within these minerals available for bioreduction, the use of partial bio-oxidation as a pretreatment to oxidize the sulfides to elemental sulfur was investigated in gas lift loop reactor experiments. Experiments at 35 °C using a refractory concentrate showed that at pH 2 arsenopyrite is preferentially partially oxidized over pyrite and that elemental sulfur can be subsequently converted into H2S at pH 5 via bioreduction using H2 gas. A single partial bio-oxidation/bioreduction treatment increased the gold recovery of the concentrate from 6% to 39%. As elemental sulfur seems to inhibit further oxidation by covering the mineral surface, several treatments may be required to reach a gold recovery >90%. Depending on the number of treatments this method could be an interesting alternative to bio-oxidation
    Telers kunnen in theorie zonder pijpzwavel
    Neefjes, H. ; Wageningen UR Glastuinbouw, - \ 2011
    Vakblad voor de Bloemisterij 66 (2011)32. - ISSN 0042-2223 - p. 32 - 32.
    meeldauw - plantenziektebestrijding - gewasbescherming - teelt onder bescherming - pesticiden - zwavel - siergewassen - sierteelt - bestrijdingsmethoden - alternatieve methoden - mildews - plant disease control - plant protection - protected cultivation - pesticides - sulfur - ornamental crops - ornamental horticulture - control methods - alternative methods
    Er zijn genoeg alternatieven voor de beheersing van echte meeldauw zonder pijpzwavel. Zo luidt de conclusie van Wageningen UR Glastuinbouw na een inventarisatie. Maar veelal gaat het om combinaties van alternatieven en is doorontwikkeling naar praktijktoepassing nog nodig.
    Telen zonder pijpzwavel is goed mogelijk: Genoeg alternatieven tegen echte meeldauw (interview met Jantineke Hofland-Zijlstra)
    Arkesteijn, M. ; Staaij, M. van der - \ 2011
    Onder Glas 8 (2011)4. - p. 46 - 47.
    glastuinbouw - teelt onder bescherming - plantenziekteverwekkende schimmels - meeldauw - plantenziekten - bestrijdingsmethoden - zwavel - alternatieve methoden - potplanten - snijbloemen - groenten - greenhouse horticulture - protected cultivation - plant pathogenic fungi - mildews - plant diseases - control methods - sulfur - alternative methods - pot plants - cut flowers - vegetables
    Echte meeldauwschimmels kunnen aardig wat schade veroorzaken in verschillende tuinbouwgewassen. In een deel van deze gewassen is het verdampen van pijpzwavel in zwavelpotten een effectieve maatregel om deze schimmels te bestrijden. Maar hoe lang kan en mag zwavel nog worden gebruikt en welke alternatieven zijn er? Een aantal alternatieven op een rijtje.
    Zwavelvoorziening op melkveebedrijven : tekorten leiden tot verminderde eiwitvorming bij plant en dier
    Eekeren, N.J.M. van; Govaerts, W. ; Smolders, E.A.A. - \ 2010
    Ekoland 30 (2010)4. - ISSN 0926-9142 - p. 24 - 25.
    zwavel - mineraaltekorten - rundvee - schapen - geiten - bijvoeding - melkveehouderij - diergezondheid - bemesting - sulfur - mineral deficiencies - cattle - sheep - goats - supplementary feeding - dairy farming - animal health - fertilizer application
    Een ketting is zo sterk als de zwakste schakel, en zwavelvoorziening lijkt op biologische melkveebedrijven steeds meer de zwakste schakel te worden. Door luchtverontreiniging kwam zwavel jarenlang gratis uit de lucht. Nu dit milieuprobleem is opgelost, krijgt de landbouw steeds meer te maken met zwaveltekorten, want zwavel is een essentieel element voor de vorming van verschillende aminozuren en daarmee van eiwit.
    Zwavel schadelijk voor biologische bestrijders
    Pijnakker, J. ; Ramakers, P.M.J. - \ 2009
    Vakblad voor de Bloemisterij 64 (2009)24. - ISSN 0042-2223 - p. 43 - 43.
    tuinbouwbedrijven - tuinbouw - siergewassen - meeldauw - zwavel - biologische bestrijding - natuurlijke vijanden - plaagbestrijding met natuurlijke vijanden - uitzettingstechnieken - glastuinbouw - market gardens - horticulture - ornamental crops - mildews - sulfur - biological control - natural enemies - augmentation - release techniques - greenhouse horticulture
    Zwavel is een van de oudste fungiciden en het is lastig te combineren met biologische bestrijders. Voor veel beestjes is het fataal. WUR Glastuinbouw kreeg het verzoek uit te zoeken hoe het u zit met zwavel en biologische bestrijders
    A kinetic approach to evaluate the association of acid volatile sulfide and simultaneously extracted metals in aquatic sediments
    Poot, A. ; Meerman, E. ; Gillissen, F. ; Koelmans, A.A. - \ 2009
    Environmental Toxicology and Chemistry 28 (2009)4. - ISSN 0730-7268 - p. 711 - 717.
    anoxic marine-sediments - fresh-water sediments - floodplain lakes - acute toxicity - mud lake - avs - sulfur - minerals - florida - copper
    The acid volatile sulfide (AVS) and simultaneously extracted metals (¿SEM) method is widely used for evaluating potential bioavailability of heavy metals in soil and sediment. It is also criticized, because the requirement that AVS and SEM metals (i.e., Cd, Cu, Ni, Pb, and Zn) are associated in the same phase is not always met. Here, we propose a dissolution-kinetics-based approach to assess whether AVS and ¿SEM originate from the same phase, as a prescreening tool for ¿SEM-AVS-based risk assessment or site characterization. Acid volatile sulfide and SEM metals from the same phase are assumed to yield equal dissolution rates. Therefore, dissolution rates for AVS and SEM metals were measured using a modified purge-and-trap method. Results were interpreted in terms of a shrinking particle model and a first-order model, which performed equally well. Of the SEM metals, only Cu showed reaction kinetics similar to those of AVS. Extraction of Fe and SEM-Zn (which constituted more than 90% of ¿SEM) was much faster than AVS and did not fit to the models. This suggests that they are not associated with AVS but also that AVS is probably not present as sulfide minerals. These data illustrate that the ¿SEM-AVS risk assessment concept would not be applicable for the studied sediments
    Assessment of nutrient deficiencies in maize in nutrient omission trials and long-term field experiments in the West African Savanna
    Nziguheba, G. ; Tossah, B.K. ; Diels, J. ; Franke, A.C. ; Aihou, K. ; Iwuafor, E.N.O. ; Nwoke, C. ; Merckx, R. - \ 2009
    Plant and Soil 314 (2009)1-2. - ISSN 0032-079X - p. 143 - 157.
    sulfur - soil - management - systems - balances - nigeria - regions - copper - wheat - yield
    Low soil fertility is one of the main constraints to crop production in the West African savanna. However, the response of major cereals to fertilizer applications is often far below the potential yields. Low fertilizer efficiency, inadequacy of current fertilizer recommendations, and the ignorance of nutrients other than N, P, and K may limit crop production. Nutrient limitations to maize production were identified in on-farm trials in Togo and in several long-term experiments in Nigeria and Benin. Maize ear leaf samples were analyzed for macro and micro-nutrients, and the Diagnosis and Recommendation Integrated Systems (DRIS) was applied to rank nutrients according to their degree of limitation to maize. In the on-farm trials, both yield and DRIS results indicated that, when N is supplied, P limited maize production in all fields, reducing yields by 31% on average. Sulfur was limiting in 81% of the fields and was responsible for an average yield reduction of 20%. In the long-term experiments where N, P, and K had been annually applied, Ca and Mg indices were strongly negative, indicative of deficiency. Zn indices were negative in all trials. Despite N-fertilizer additions, N indices remained negative in some of the long-term experiments, pointing to low efficiency of applied fertilizers. There was a direct link between DRIS indices and the management imposed in the different experiments, indicating that DRIS is a useful approach to reveal nutrient deficiencies or imbalances in maize in the region.
    Relation between Critical Load Exceedance and Loss of Protected Species
    Hinsberg, A. van; Reijnen, R. ; Goedhart, P.W. ; Knegt, B. de; Esbroek, M.L.P. van - \ 2008
    In: Critical load, dynamic modelling and impact assessment in Europe / Hettelingh, J.P., Posch, M., Slootweg, J., Den Haag : Nederlands Environmental Assessment Agency (CCE Status Report 2008) - ISBN 9789069602110 - p. 73 - 82.
    ecosystemen - stikstof - zwavel - emissie - europa - natura 2000 - ruimtelijke databases - ecosystems - nitrogen - sulfur - emission - europe - natura 2000 - spatial databases
    This report describes the 2008 European database on spatially-explicit critical loads and dynamic modelling data (2008 CL database). It analyses the underlying fundamentals of the 2008 CL database, and provides examples of its use in the assessing of the magnitude and location of the risk of current and future impacts of nitrogen and sulphur on ecosystems in Europe, including the Natura 2000 areas. The report emphasises the risk of impacts caused by the deposition of oxidised and reduced nitrogen.
    Sulfate Reduction at pH 4 During the Thermophilic (55 degrees C) Acidification of Sucrose in UASB Reactors
    Lopes, S.I.C. ; Capela, M.I. ; Dar, S.A. ; Muyzer, G. ; Lens, P.N.L. - \ 2008
    Biotechnology Progress 24 (2008)6. - ISSN 8756-7938 - p. 1278 - 1289.
    acid-mine drainage - gradient gel-electrophoresis - anaerobic granular sludge - in-situ hybridization - mill waste-water - sp-nov - reducing bacterium - metal fractionation - bioreactor - sulfur
    Continuous sulfate reduction at pH 4.0 was demonstrated in a pH controlled thermophilic (55 degrees C) upflow anaerobic sludge bed reactor fed with sucrose at a COD/SO42- ratio of 0.9 and an organic loading rate of 0.8 and 1.9 gCOD (l(reactor) d)(-1) for a period of 78 days. A near v complete sulfate reduction efficiency was achieved throughout the reactor run, corresponding to sulfate removal rates of 0.91 and 1.92 g (l(reactor) d)(-1) at sulfate loading rates of 0.94 and 2 g (l(reactor) d)(-1), respectively, by keeping the sulfide concentration below 20 mg l(-1) due to stripping with nitrogen gas. Acidification was always complete and acetate was the only, degradation intermediate left in the effluent, which did not exceed 180 mgCOD l(-1) in pseudo-stationary states. The sludge was well retained ill the reactor and kept its granular form. A, Cu, Se, and Mo accumulated in the sludge, whereas Co, Ni, Fe, and Mn leached from the sludge, despite their continuous supply to the reactor via the influent. The bacterial diversity in the reactor sludge at the end of the reactor run was low and the culture was dominated by one acidifying species, resembling Thermoanaerobacterium sp., and one sulfate reducing species, resembling Desulfotomaculum sp.
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