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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    Salt Tolerance Mechanisms of Plants
    Zelm, Eva Van; Zhang, Yanxia ; Testerink, Christa - \ 2020
    Annual Review of Plant Biology 71 (2020). - ISSN 1543-5008 - p. 403 - 433.
    ABA - auxin - developmental plasticity - ionic stress - osmotic stress - salinity

    Crop loss due to soil salinization is an increasing threat to agriculture worldwide. This review provides an overview of cellular and physiological mechanisms in plant responses to salt. We place cellular responses in a time- and tissue-dependent context in order to link them to observed phases in growth rate that occur in response to stress. Recent advances in phenotyping can now functionally or genetically link cellular signaling responses, ion transport, water management, and gene expression to growth, development, and survival. Halophytes, which are naturally salt-tolerant plants, are highlighted as success stories to learn from. We emphasize that (a) filling the major knowledge gaps in salt-induced signaling pathways, (b) increasing the spatial and temporal resolution of our knowledge of salt stress responses, (c) discovering and considering crop-specific responses, and (d) including halophytes in our comparative studies are all essential in order to take our approaches to increasing crop yields in saline soils to the next level.

    Restoration of inland brackish vegetation by large-scale transfer of coastal driftline material
    Wolters, Mineke ; Vries, Saskia de; Ozinga, Wim A. ; Bakker, Jan P. - \ 2017
    Applied Vegetation Science 20 (2017)4. - ISSN 1402-2001 - p. 641 - 650.
    brackish habitat - dispersal - driftline - grazing - saline habitat - salinity - sheep - target species - top soil removal - transfer rate

    Question: Does large-scale transfer of coastal driftline material enhance the establishment of inland brackish vegetation?. Location: The Klutenplas of 11 ha, a formerly reclaimed agricultural field, north coast of the Netherlands. Methods: A large quantity of coastal driftline material of local origin was transferred to the restoration site in 2006 after top soil removal in 2005 leaving bare areas for control plots. A priori species composition of the driftline was analysed in a greenhouse germination study. Target species were assigned to saline and brackish ecological species groups and present and historic regional occurrences. Our procedure for selecting target species resulted in a list of 98 species characteristic of terrestrial salt and brackish ecological species groups. The establishment of plant species in the field was recorded annually from 2006 to 2009, with a final survey in 2012. A comparison between locations with and without driftline was made. The entire study site was grazed with sheep. Results: Driftline material contained 39 species, including 26 target species. During the first 4 yr, the mean number of target species in the established vegetation of driftline plots was significantly higher than in control plots. When corrected for spontaneous occurrence by natural colonization in control plots, 44% of the target species in the established vegetation of driftline plots during the first 4 yr could be attributed to the transferred material. After 7 yr driftline and control plots converged to similar levels, probably as a result of dispersal by wind and animals. Conclusions: Transfer of coastal driftline material enhanced the rate of establishment of inland brackish vegetation for at least the first 4 yr.

    Fresh Water Lens Persistence and Root Zone Salinization Hazard Under Temperate Climate
    Stofberg, Sija F. ; Oude Essink, G.H.P. ; Pauw, Pieter S. ; Louw, Perry G.B. de; Leijnse, Anton ; Zee, Sjoerd E.A.T.M. van der - \ 2017
    Water Resources Management 31 (2017)2. - ISSN 0920-4741 - p. 689 - 702.
    Fresh water lens - Root zone salinization - Salinity - Simple model - salinization - fresh water - models - water supply - coastal areas - zoutgehalte - verzilting - zoet water - modellen - watervoorziening - kustgebieden

    In low lying deltaic areas in temperate climates, groundwater can be brackish to saline at shallow depth, even with a yearly rainfall excess. For primary production in horticulture, agriculture, and terrestrial nature areas, the fresh water availability may be restricted to so-called fresh water lenses: relatively thin pockets of fresh groundwater floating on top of saline groundwater. The persistence of such fresh water lenses, as well as the quantity and quality of surface water is expected to be under pressure due to climate change, as summer droughts may intensify in North-West Europe. Better understanding through modelling of these fresh water resources may help anticipate the impact of salinity on primary production. We use a simple model to determine in which circumstances fresh water lenses may disappear during summer droughts, as that could give rise to enhanced root zone salinity. With a more involved combination of expert judgement and numerical simulations, it is possible to give an appraisal of the hazard that fresh water lenses disappear for the Dutch coastal regions. For such situations, we derive an analytical tool for anticipating the resulting salinization of the root zone, which agrees well with numerical simulations. The provided tools give a basis to quantify which lenses are in hazard of disappearing periodically, as well as an impression in which coastal areas this hazard is largest. Accordingly, these results and the followed procedure may assist water management decisions and prioritization strategies leading to a secure/robust fresh water supply on a national to regional scale.

    Recirculatie bij Cymbidium
    Kromwijk, J.A.M. ; Voogt, W. - \ 2015
    cymbidium - zoutgehalte - teeltsystemen - glastuinbouw - tuinbouw - recirculatiesystemen - natrium - proeven - monitoring - cymbidium - salinity - cropping systems - greenhouse horticulture - horticulture - recirculating systems - sodium - trials - monitoring
    Tot voor kort had het gewas Cymbidium een vrijstelling voor recirculatie vanwege de zoutgevoeligheid van het gewas en lage EC in de gift. Daardoor is er weinig kennis en ervaring met recirculatie. Voor Cymbidium is nog niet bekend wat de effecten van Natrium zijn. Daarom is onderzoek gestart om vast te stellen bij welk Natriumniveau in de voeding nadelige effecten op gaan treden.
    Geen extra chips na zoutarm eten
    Janssen, A.M. - \ 2015
    WageningenWorld (2015)2. - ISSN 2210-7908 - p. 6 - 6.
    voedingsmiddelen - zoutgehalte - smaak - voedingsonderzoek bij de mens - reductie - gezondheidsgevaren - gezondheidsbevordering - behoeftenbevrediging - foods - salinity - taste - human nutrition research - reduction - health hazards - health promotion - need gratification
    Minder zout in etenswaren zorgt ervoor dat mensen daadwerkelijk minder zout eten; ze zoeken geen zoutcompensatie op andere momenten van de dag.
    Smart irrigation based on soil indicators for moisture, EC and temperature
    Balendonck, Jos - \ 2015
    irrigation - salinity - temperature - relative humidity - outturn - trickle irrigation - turkey - recirculating systems
    Waterkwaliteit en landbouw: mag het ook een beetje zouter zijn?
    Bakel, J. van; Kielen, N. ; Clevering, O.A. ; Roest, C.W.J. - \ 2015
    H2O : tijdschrift voor watervoorziening en afvalwaterbehandeling 43 (2015)5. - ISSN 0166-8439 - p. 56 - 59.
    bodemwater - zoutgehalte - normen - beschadigingen door droogte - gewassen - gewasverliezen - akkerbouw - agrohydrologie - bodemtypen - soil water - salinity - standards - drought injury - crops - crop losses - arable farming - agrohydrology - soil types
    Door de te verwachten gevolgen van de klimaatverandering zal de zoetwatervoorziening van Nederland de komende jaren worden heroverwogen. Daarbij zijn de berekening van de zoutschade in de landbouw als gevolg van beregening met niet-zoet oppervlaktewater en de hantering van normen voor toelaatbare chlorideconcentraties in het oppervlaktewater belangrijke onderdelen. In 2009 is het hierop betrekking hebbende deel van het huidige Droogte-instrumentarium geëvalueerd, gebruik makend van het agrohydrologisch SWAP model. In het aandachtsgebied zijn vier gewassen (gras, aardappelen, suikerbieten en tulpen) op drie grondsoorten (zavel, zand en klei) het meest relevant. Als belangrijkste bevindingen dat de berekening van de zoutschade niet onjuist is, maar dat de gehanteerde normen voor toelaatbare chlorideconcentraties in het oppervlaktewater leiden tot te veel droogteschade en herziening behoeven
    Ion exchange membranes in seawater applications : processes and characteristics
    Galama, A.H. - \ 2015
    Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Jan Post; Maarten Biesheuvel. - Wageningen : Wageningen University - ISBN 9789462572256 - 272
    drinkwater - ontzilting - ontziltingsinstallaties - elektrodialyse - omgekeerde osmose - membraanpermeabiliteit - zoutgehalte - economische haalbaarheid - drinking water - desalination - desalination plants - electrodialysis - reverse osmosis - membrane permeability - salinity - economic viability

    Officiële titel ENG: Ion exchange membranes in seawater applications. Processes and characteristics

    Officiële titel NL: Ionwisselende membranen in zeewatertoepassingen. Processen en eigenschappen

    Auteur: A.H.Galama

    Jaar: 2015

    ISBN: 978-94-6257-225-6

    Samenvatting

    Zeewaterontzouting stelt mensen in staat om zoet water te maken uit een schijnbaar oneindige water voorraad. Om water ook echt beschikbaar te maken is het een voorwaarde dat de kosten van het ontzoutingsproces zo laag mogelijk zijn. Door gebruik van elektrodialyse (ED), een elektrochemische membraantechnologie voor ontzouting, kunnen de kosten van het ontzoutingsproces mogelijk worden verlaagd. In deze thesis worden de energetische aspecten van ED nader bekeken. De opgelegde hoeveelheid stroom blijkt daarin erg bepalend. Tevens worden de ionwisselende membranen, die in deze toepassing worden gebruikt, nader onderzocht. In de huidige technologische staat kan ED, wat betreft energie en kosten, op grote schaal niet concurreren met omgekeerde osmose. Om ED echt concurrerend te kunnen maken zal de ionische membraanweerstand moeten worden verlaagd en zal de membraanprijs moeten dalen. Voor toepassingen waar een hoge waterefficiëntie nodig is, denk aan ‘zero-liquid-discharge’ ontzoutingsprocessen, lijkt ED aantrekkelijk om als voorontzoutingstechnologie in te zetten.

    Tree-ring d18O in African mahogany (Entandrophragma utile) records regional precipitation and can be used for climate reconstructions
    Sleen, J.P. van der; Groenendijk, P. ; Zuidema, P. - \ 2015
    Global and Planetary Change 127 (2015). - ISSN 0921-8181 - p. 58 - 66.
    oxygen-isotope ratios - tropical atlantic - west-africa - monsoon - growth - forest - chronologies - temperature - variability - salinity
    The availability of instrumental climate data in West and Central Africa is very restricted, both in space and time. This limits the understanding of the regional climate system and the monitoring of climate change and causes a need for proxies that allow the reconstruction of paleoclimatic variability. Here we show that oxygen isotope values (d18O) in tree rings of Entandrophragma utile from North-western Cameroon correlate to precipitation on a regional to sub-continental scale (1930–2009). All found correlations were negative, following the proposed recording of the ‘amount effect’ by trees in the tropics. The capacity of E. utile to record the variability of regional precipitation is also confirmed by the significant correlation of tree-ring d18O with river discharge data (1944–1983), outgoing longwave radiation (a proxy for cloud cover; 1974–2011) and sea surface salinity in the Gulf of Guinea (1950–2011). Furthermore, the high values in the d18O chronology from 1970 onwards coincide with the Sahel drought period. Given that E. utile presents clear annual growth rings, has a wide-spread distribution in tropical Africa and is long lived (> 250 years), we argue that the analysis of oxygen isotopes in growth rings of this species is a promising tool for the study of paleoclimatic variability during the last centuries in West and Central Africa.
    The potential effect of greenwater technology on water quality in the pond culture of Penaeus monodon Fabricius
    Tendencia, E.A. ; Bosma, R.H. ; Verdegem, M.C.J. ; Verreth, J.A.J. - \ 2015
    Aquaculture Research 46 (2015)1. - ISSN 1355-557X - p. 1 - 13.
    white-spot-syndrome - syndrome virus - shrimp ponds - litopenaeus-vannamei - chlorella-vulgaris - vibrio-harveyi - salinity - temperature - susceptibility - mortalities
    Whitespot syndrome virus (WSSV) has caused severe production drops in the shrimp industry. Numerous scientific manuscripts deal with WSSV epidemiology, but reports on minimizing disease outbreaks through ecological means are rare. Industry stakeholders resorted to various innovative techniques to recover from heavy economic losses. Some shrimp farmers in the Philippines claimed that 'greenwater' (GW) technology could prevent disease outbreaks due to WSSV. The efficiency of the GW technology was evaluated by comparing three ponds using the GW culture technique with three ponds not using it. WSSV was detected only in one of the GW ponds and not in the non-GW ponds. No WSSV disease outbreak occurred, and no conclusion could be reached. In GW ponds, available soil sulphur content was lower; and in water, the observed counts of luminous bacteria were lower and counts of Chlorophyceae were higher. Chlorophyceae, i.e. algae, enhanced nutrient uptake in effluent streams resulting in improved water quality in Penaeus monodon Fabricius culture ponds. This suggests that the use of the GW technique to culture P. monodon improved water quality.
    High relative air humidity influences mineral accumulation and growth in iron deficient soybean plants
    Roriz, M. ; Carvalho, S.M.P. ; Wilton Vasconcelos, M. - \ 2014
    Frontiers in Plant Science 5 (2014). - ISSN 1664-462X - 24 p.
    metabolic-responses - greenhouse plants - nutrient-uptake - human-nutrition - seed treatment - chlorosis - homeostasis - roots - salinity - crops
    Iron (Fe) deficiency chlorosis (IDC) in soybean results in severe yield losses. Cultivar selection is the most commonly used strategy to avoid IDC but there is a clear interaction between genotype and the environment; therefore, the search for quick and reliable tools to control this nutrient deficiency is essential. Several studies showed that relative humidty (RH) may influence the long distance transport of mineral elements and the nutrient status of plants. Thus, we decided to analyze the response of an ‘Fe-efficient’ (EF) and an ‘Fe-inefficient’ (INF) soybean accession grown under Fe-sufficient and deficient conditions under low (60%) and high (90%) RH, evaluating morphological and physiological parameters. Furthermore, the mineral content of different plant organs was analyzed. Our results showed beneficial effects of high RH in alleviating IDC symptoms as seen by increased SPAD values, higher plant dry weight, increased plant height, root length and leaf area. This positive effect of RH in reducing IDC symptoms was more pronounced in the EF accession. Also, Fe content in the different plant organs of the EF accession grown under deficient conditions increased with RH. The lower partitioning of Fe to roots and stems of the EF accessions relative to dry matter also supported our hypothesis, suggesting a greater capacity of this accession in Fe translocation to the aerial parts under Fe deficient conditions, when grown under high RH.
    Seawater predesalination with electrodialysis
    Galama, A.H. ; Saakes, M. ; Bruning, H. ; Rijnaarts, H.H.M. ; Post, J.W. - \ 2014
    Desalination 342 (2014). - ISSN 0011-9164 - p. 61 - 69.
    ion-exchange membranes - electroosmotic water transport - resin membranes - desalination processes - power - electrotransport - salinity - reversal - system - model
    The suitability of ED for seawater desalination was investigated and we quantified the energy losses that play a role in electrodialysis. The combination of electrodialysis (ED) and brackish water reverse osmosis (BWRO) is presented as an alternative desalination strategy for seawater reverse osmosis (SWRO). Experiments have been performed with a recycling batch electrodialyzer. From this we conclude that in most cases the membrane stack is responsible for the main energy loss in the system. Energy losses due to water transport are generally low. At low applied current density, osmotic water transport is relatively large and as such the energy loss, while electroosmosis was found to be directly proportional to the applied current density. The relative energy loss caused by back diffusion was found to be only of minor importance for higher current densities and was only more pronounced at the lowest applied current density of 10 A/m2. Combining ED with BWRO in a hybrid system does not lead to a reduction in energy consumption compared to ED as standalone technique, when the applied current density becomes lower than 50 A/m2. At low applied current density (10 A/m2) ED can perform desalination energetically cheaper at lower operational costs than SWRO.
    Bloemkool geteeld op water 2013
    Blind, M. - \ 2013
    Zwaagdijk : Proeftuin Zwaagdijk - 50 p.
    teeltsystemen - vollegrondsgroenten - hydrocultuur - bloemkolen - proeven op proefstations - plantdichtheid - zoutgehalte - cultuurmethoden - cropping systems - field vegetables - hydroponics - cauliflowers - station tests - plant density - salinity - cultural methods
    In de afgelopen jaren is gebleken dat het mogelijk is bloemkool op het drijvende teeltsysteem te telen maar dat het percentage klasse 1 nog te laag is. Over het algemeen verloopt de gewasontwikkeling in de eerste fase zeer goed. In de eindfase – als de koolvorming plaatsvindt - ontstaan veelal problemen met verwelking. Een duidelijke oorzaak voor de snelle achteruitgang in vitaliteit is nog niet aan te wijzen. Een oorzaak zou kunen zijn een vorm van stress die in de laatste fase van de teelt ontstaat. Het gewas wordt topzwaar en is gevoelig voor wind, ook omdat de groei in de eerste fase juist erg weelderig is. Eén van de doelen van de proeven in 2013 was daarom te onderzoeken of een ruimere plantafstand leidt tot een betere kwaliteit. Een andere techniek om de planten compacter te laten groeien zou het telen bij een hoger zoutgehalte (EC) kunnen zijn. Doordat de planten bij een hoger zoutgehalte minder makkelijk water kunnen opnemen blijven ze compacter.
    Anaerobic wastewater treatment of high salinity wastewaters: impact on bioactivity and biomass retention
    Ismail, S. - \ 2013
    Wageningen University. Promotor(en): Jules van Lier, co-promotor(en): Hardy Temmink; Caroline Plugge. - Wageningen : Wageningen UR - ISBN 9789461738189 - 144
    afvalwaterbehandeling - waterzuivering - afvalwater - anaërobe behandeling - zoutgehalte - biomassa - waste water treatment - water treatment - waste water - anaerobic treatment - salinity - biomass

    Anaerobic sludge bed reactor systems like the upflow anaerobic sludge blanket (UASB) and expended granular sludge bed (EGSB) reactors are currently the mostly applied high-rate reactor systems for anaerobic wastewater treatment. The success of both systems has changed the world conception of wastewater treatment with energy recovery being an intrinsic part of the treatment process, avoidance of excess sludge problems and extremely low space requirement. Nevertheless, while broadening the UASB reactor application to a diverse type of wastewaters, high salinity wastewaters were found to give an adverse effect to the granulation processes. Accumulation of Na+at high concentrations produced weaker and fluffy granules endangering the applicability of the mentioned sludge bed systems. In this thesis, research was conducted to investigate the mechanisms of destabilization of the granules at high Na+concentrations, while trying to improve the granules’ properties. Chapter 1gives an overview of high salinity wastewaters, the application and the bottlenecks of anaerobic wastewater treatment (AnWT) technology under extreme conditions. Focus is given to the granulation process as a key factor in the operation of high rate anaerobic reactors. Indeed, it is a complex process that involves physicochemical as well as biological mechanisms. A short overview of the previous research on anaerobic wastewater treatment processes for high salinity wastewaters is discussed, followed by granulation theories and processes. Referring to the imbalance in the monovalent to divalent cation ratio, the Ca2+augmentation approach is discussed in this chapter as a tool to establish a favourable ratio for the required granulation process. The chapter also discusses the need for extracellular polymeric substances (EPS) production, depending on the types of substrates, as a major factor for a successful granulation process. Specifically for high Na+concentrations, also the importance of K+and more specifically the K+/Na+ratio is discussed as a control regulator to alleviate the negative effects of Na+. Finally, the review discusses microbiological aspects related to the anaerobic treatment of high salinity wastewaters such as the adaptation of sludge to high Na+concentrations and the presence of halophilic/halotolerent microorganisms and their application in anaerobic wastewater treatment.

    In Chapter 2, the effects of high Na+concentrations on methanogenic sludge bed reactor systems were investigated. In three different UASB reactors a rapid acclimation to 5 or 15 g Na+/L was observed, showing satisfactory results for a period of 100 days, when the reactors were fed with a mixture of acetate, gelatine and ethanol. Loading rates up to at least 18 kg COD/m3.d gave a good COD removal performance and the cultivated sludge showed high specific methanogenic activities (SMA) on acetate, propionate, butyrate and H2compared to the inoculated granules. Remarkably, only the reactor which was operated at a lower COD (5 instead of 50 g/L) exhibited severe washout, probably due to the much shorter HRT that was applied, i.e. 12 hours compared to 120 hours. Interestingly, the SMA of the biomass that washed out from this reactor showed considerably higher SMAs than the washed-out biomass from the other reactors. The performance of the granular sludge systems in this study shows the appropriateness of anaerobic inocula, pre-grown under saline conditions for the anaerobic treatment of high salinity wastewater.

    In Chapter 3the production of EPS in UASB reactor systems that were operated under high salinity conditions was investigated. Four different UASB reactors were operated at loading rates up to 22 kg COD/m3.d with different acetate:gelatine:starch ratios as the substrate. Reactors were fed with partially acidified and fully acidified substrates, i.e. PAS and FAS respectively, and Na+concentrations of either 10 or 20 g Na+/L. One of the reactors additionally received 1 g of Ca2+/L. All four reactors showed a good performance with COD removal efficiencies exceeding 90 %. Proteins were the dominant EPS and the PAS-fed granules gave much higher EPS concentrations than FAS-fed granules. However, the proteins concentration was found not dependent on the Na+ concentration in the feed. Interestingly, the granules from the reactors which were operated at a Na+/Ca2+ratio of 770 contained more polysaccharides than granules from reactors operated at a high Na+/Ca2+ratio of 1540. SEM images showed that that PAS-fed granule had a smoother granule surfaces than FAS-fed granule. PAS-fed granules also were considerably larger than FAS-fed granules. When the influent contained additional Ca2+, clear cracks or fissures could be observed on the surface of the granules. Na+ concentrations of 10 g/L seemed to increase the granule size, which may have been caused by swelling of the EPS matrix. Shear tests indicated that PAS-fed granules were stronger than the FAS fed granules and that Ca2+ addition had a positive effect on granule strength. The calcium content of these granules also was higher with 150 mg/g TSS compared to 60 mg/g TSS in the other reactors. Batch tests at high Na+concentrations confirmed calcium leaching from the granules. When granular sludge was exposed to 20 g Na+/L in batches, leaching of Ca2+from granules took place with a maximum obtained after 10 days. The calcium content of the granules decreased from approximately 85 to 52 mg/g TSS. Therefore, the highest Na+concentrations resulted in the weakest granules.

    Chapter 4describes the results of batch incubation studies in which anaerobic granular sludge was augmented with 0.3 g Ca2+/L at Na+concentrations of 20 g/L. Experiments followed the previously described results of Chapter 3 showing that high Na+concentrations caused Ca2+leaching from anaerobic granules. Extensive SEM-EDX and SEM-BSE measurements confirm leaching of calcium from the granules when these are exposed to higher Na+ concentrations. Moreover Ca2+additions seemed to indeed maintain the Ca2+content of granular sludge.

    Initial attachment of microorganism is very important for the development of granules and biofilms. Therefore, biofilm studies were conducted and explained in Chapter 5. Four different biofilm reactors with a non-woven carrier material were exposed to different Na+ concentrations (10 or 20 g/L) and inoculated with crushed granules. Acetate was used as the substrate. One of the reactors received 0.3 g Ca2+/L and another one 0.7 g K+/L. The reactors were operated as sequencing batches. The reactor fed with K+ gave the best performance. Lower salinity (10 compared to 20 g Na+/L) improved the performance and the reactor which received calcium gave the worst results. This finding contradicts with previous experiments in Chapter 3. However, the situation in the biofilm reactors is completely different because the biofilms had to form from scratch. FISH-CLSM images revealed no significant visible differences in microbial coverage (i.e. bacteria and archea) of the non-woven fabric, except for the calcium enriched reactor. After 40 days of operation, it was clearly observed that 20 g Na+/L does not prevent the initial microbial attachment under anaerobic conditions. From 16 sRNA DGGE measurements it was shown that the biofilms had a similar population and that this population did not change very much in time. The Archea were related to Methanosaeta harundinacae (acetoclastic), Methanolinea tarda and Methanobacterium subteraaneum (both hydrogenotrophic). Apparently these species can easily adapt to high salinity. However, the biofilms in the reactors did not show any of the known acetate-oxidizing bacteria that are expectedly needed for the production of H2from acetate as source for the growth of the found hydrogenotrophic Archea. Therefore, it is assumed that H2leakage by acetoclastic methanogen explain their presence in the reactor.

    Four identical UASB reactors treating concentrated wastewaters (10 – 30 g COD/L) were operated at 20 g Na+/L and in detail described in Chapter 6. PAS and FAS substrates were fed to different reactors to compare the effect of different organic substrates on granule activity, stability and growth. The effect of calcium augmentation on anaerobic granules’ properties was studied by feeding two of the reactors with additional calcium at a concentration of 0.3 g Ca2+/L. A beneficial effect of potassium was demonstrated in Chapter 5 and it therefore was added to all the reactors, at a concentration of 0.7 g K+/L. The treatment performance of the reactors was compared during a period of 120 days at increasing volumetric organic loading rates (OLRs). Physicochemical and microbiological properties of the anaerobic granules were determined and discussed. The results showed that high COD removal efficiencies are possible at 20 g Na+/L, up to an organic loading rate of at least 14 g COD/L.d. At a loading rate of 25 g COD/L.d the performance and stability of all reactors deteriorated. There were indications that calcium augmentation had a positive effect on biomass retention, but this could not be further quantified. The microbial assays gave similar results as in Chapter 5. Compared to the inoculum, bacterial diversity in FAS-fed granules did not change significantly but was changed considerably in PAS-fed granules. Complex organic PAS feed resulted in more complex bacterial populations that were not related to archea. The bacterial presence of a dominant phylotype, belonging to the family of Marinilabiliaceaeand specifically Alkaliflexus imshenetskiiwas evidenced. Members of Marinilabiliaceae are capable of degrading polymeric substances such as starch and gelatine. The dominant archeal species in the reactors was related to Methanosaeta harundinacea. Methanosaetahave been found to play a major role in granulation

    In Chapter 7the results of this research are discussed in a general context. Directions for further research are presented focussing on the increase in biomass activity and biomass retention in high salinity wastewaters by improving the adaptability of microbes and the anaerobic sludge granulation process.

    Capacitive technology for energy extraction from chemical potential differences
    Bastos Sales, B. - \ 2013
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Bert Hamelers. - S.l. : s.n. - ISBN 9789461737380 - 120
    capacitantie - bio-elektrische potentiaal - hernieuwbare energie - energiebronnen - zoutgehalte - elektrische kracht - temperatuur - capacitance - bioelectric potential - renewable energy - energy sources - salinity - electric power - temperature

    This thesis introduces the principle of Capacitive energy extraction based on Donnan Potential (CDP) to exploit salinity gradients. It also shows the fundamental characterization and improvements of CDP. An alternative application of this technology aimed at thermal gradients was tested.

    Chapter 2 introduces the principle and initial tests. The entropy increase of mixing two solutions of different salt concentrations can be harnessed to generate electrical energy. Worldwide, the potential of this resource, the controlled mixing of river and seawater, is enormous, but existing conversion technologies are still complex and expensive. Here we present a small-scale device that directly generates electrical power from the sequential flow of fresh and saline water, without the need of auxiliary processes or converters. The device consists of a sandwich of porous “supercapacitor” electrodes, ion-exchange membranes, and a spacer and can be further miniaturized or scaled-out. Our results demonstrate that alternating the flow of saline and fresh water through a capacitive cell allows direct autogeneration of voltage and current and consequently leads to power generation. Theoretical calculations aid in providing directions for further optimization of the properties of membranes and electrodes.

    In Chapter 3, traditional electrochemical techniques (galvanostatic charge–discharge and cyclic voltammetry) were used to investigate intrinsic properties of this open system. This study demonstrates the feasibility to characterize the capacitive behavior of the cell in low concentration (0.5 M). Presence of membranes, as well as the possibility of having the electrolyte flowing through the cell was investigated. In the studied cell, the presence of membranes showed a limitation by the anion exchange membrane at low current densities but no effect at high current densities. The flow rate did not influence the capacitance of the system either.

    Chapter 4uses again a stack of eight cells coupled in parallel to investigate the viability of this technology. An average power density of 0.055W/m2was obtained during the peak of the different cycles, though reasonable optimization suggests an expectation of 0.26W/m2at 6.2 A/m2. It was found that 83 ± 8% of the theoretical driving potential was obtained during the operating process. By studying the polarization curves during charging and discharging cycles, it was found that optimizing the feed fluid flow is currently among the most beneficial paths to make CDP a viable salinity difference power source. Another parallel route for increasing the efficiency is lowering the internal ohmic resistances of the cell by design modifications.

    A modification is proposed in Chapter 5, approaching the electrodes geometry that has a relevant impact on internal resistance and overall performance in CDP. In this work, we present the first effort to use wire-shaped electrodes and its suitability for improving CDP. Analytical evaluation and electrical measurements confirm a strong nonlinear decrease in internal resistance for distances between electrodes smaller than 3 mm. We also demonstrate that we get more power per material invested when compared to traditional flat plate designs. These findings show the advantages of this design for further development of CDP into a mature technology.

    Alternatively, in Chapter 6, we present a new principle for producing electricity from low temperature differences by using an affordable assembly combining ion exchange membranes and supercapacitor carbon electrodes. Our proposed design involves two isolated salty solutions, with equal concentration but different temperatures. The operation consists of an alternately and cyclic exposure of the electrodes to these electrolytes. This difference in temperature generates a thermomembrane potential that acts as a driving force for ionic adsorption/desorption cycles on the electrodes. Our simple system is interesting for exploiting the potential of low temperature waste heat. When two volumes with equal concentration have different temperatures, it is possible to immerse a pair of electrodes (anode and cathode) into the low temperature one and have ion adsorption. An electric current is then generated in the external circuit to achieve electro neutrality. After saturation, the same electrodes are immersed in the high T volume and then ions desorb from the electrodes and are released to the volume, leading to a reverse electric current in the external circuit compared to the first step. These experiments prove the principle and the direct dependence of the temperature gradient for energy extraction.

    Finally, Chapter 7discusses the internal energy losses identified and faced throughout this thesis. We summarize the solutions encountered for the major contributions hindering the CDP performance and give suggestions to further develop the technology.

    Ecological rehabilitation of Lac Bonaire by wise management of water and sediments
    Wosten, J.H.M. - \ 2013
    Wageningen : Alterra (Alterra-rapport 2448) - 40
    mangroves - zoutgehalte - sediment - vee - waterkwaliteit - waterbeheer - herstel - ecologisch herstel - bonaire - mangroves - salinity - sediment - livestock - water quality - water management - rehabilitation - ecological restoration - bonaire
    Lac Bonaire is confronted with a gradually decreasing open water area because mangrove is occupying this area. At the same time mangrove growth deteriorates at the back of the mangrove belt, the area of hyper saline flats gradually increases and sediment is deposited in the bay area. During a field visit, the most prominent problems are identified and concrete management actions are proposed for the ecological rehabilitation of Lac Bonaire.
    A novel hybrid process of reverse electrodialysis and reverse osmosis for low energy seawater desalination and brine management
    Li, W. ; Krantz, W.B. ; Cornelissen, E.R. ; Post, J.W. ; Verliefde, A.R.D. ; Tang, C.Y. - \ 2013
    Applied Energy 104 (2013). - ISSN 0306-2619 - p. 592 - 602.
    ion-exchange membranes - environmental-impact - power-generation - swro process - river water - salinity - plant - performance - technology - difference
    This paper introduces a novel concept for a hybrid desalination system that combines reverse electrodialysis (RED) and reverse osmosis (RO) processes. In this hybrid process the RED unit harvests the energy in the form of electricity from the salinity gradient between a highly concentrated solution (e.g., seawater or concentrated brine) and a low salinity solution (e.g., biologically treated secondary effluent or impaired water). The RED-treated high salinity solution has a lower salt concentration and serves as the feed solution for the RO unit to reduce the pump work. The concentrated RO brine provides the RED unit a better high salinity source for the energy recovery compared to seawater. In addition, the concentration of the discharged brine can be controlled by the RED unit for improving the water recovery and minimizing the impact on the environment. Different configurations of the hybrid RED–RO processes are presented for a comparative study on the basis of mathematical modeling. Specifically, various operating conditions for the RED unit are investigated for better adaptation to the hybrid system. The variations of the total specific energy consumption and the discharge brine concentration for various hybrid modes are simulated to verify the conceptual designs. The modeling results indicate that the RED–RO hybrid processes could substantially reduce the specific energy consumption and provide a better control of the discharge brine concentration in comparison to conventional seawater desalination RO processes
    A coupled agronomic-economic model to consider allocation of brackish irrigation water
    Gal, A. Ben; Weikard, H.P. ; Shah, S.H.H. ; Zee, S.E.A.T.M. van der - \ 2013
    Water Resources Research 49 (2013)5. - ISSN 0043-1397 - p. 2861 - 2871.
    agrohydrologie - irrigatie - verzilting - semi-aride klimaat - gewasproductie - modellen - agrohydrology - irrigation - salinization - semiarid climate - crop production - models - river-basin - salinity - transpiration - agriculture - stress - state
    [1] In arid and semiarid regions, irrigation water is scarce and often contains high concentrations of salts. To reduce negative effects on crop yields, the irrigated amounts must include water for leaching and therefore exceed evapotranspiration. The leachate (drainage) water returns to water sources such as rivers or groundwater aquifers and increases their level of salinity and the leaching requirement for irrigation water of any sequential user. We develop a conceptual sequential (upstream-downstream) model of irrigation that predicts crop yields and water consumption and tracks the water flow and level of salinity along a river dependent on irrigation management decisions. The model incorporates an agro-physical model of plant response to environmental conditions including feedbacks. For a system with limited water resources, the model examines the impacts of water scarcity, salinity and technically inefficient application on yields for specific crop, soil, and climate conditions. Moving beyond the formulation of a conceptual frame, we apply the model to the irrigation of Capsicum annum on Arava Sandy Loam soil. We show for this case how water application could be distributed between upstream and downstream plots or farms. We identify those situations where it is beneficial to trade water from upstream to downstream farms (assuming that the upstream farm holds the water rights). We find that water trade will improve efficiency except when loss levels are low. We compute the marginal value of water, i.e., the price water would command on a market, for different levels of water scarcity, salinity and levels of water loss
    Genetic variation in yield and chemical composition of wide range of sorghum accessions grown in north-west China
    Wang, J.S. ; Wang, M.L. ; Spiertz, J.H.J. ; Liu, Z. ; Han, L. ; Xie, G.H. - \ 2013
    Research on Crops 14 (2013)1. - ISSN 0972-3226 - p. 95 - 105.
    salinity - biofuels - drought - stress - moench
    Sorghum can be grown on marginal and waste lands as a versatile feedstock for biofuel production in the vast areas of north-west China. Fifty-six sorghum accessions were grown in 2009 at the experimental station of Xinjiang Agricultural University, located at Urumchi, Xinjiang, China. A total of 31 agronomic, crop descriptors and chemical composition traits were investigated and analyzed. Among these accessions, significant variability was identified in grain yield (0.2-11.4 t/ha), stem weight (2.1-21.8 t/ha) and total biomass (13.8-34.4 t/ha) with an average of 6.5, 8.6 and 22.6 t/ha, respectively. Significant differences in chemical composition (including soluble sugar, starch, cellulose, hemicellulose and lignin) of grain, leaf blade, leaf sheath and stem were identified. The stems of sweet sorghum contained a significantly higher amount of sugars and lower amounts of cellulose, hemicelluloses, lignin than in other two sorghum types. Highly significant correlations were detected among the investigated traits. Cluster and principal component analyses classified these 56 accessions into two main groups. Accessions : X041, X125, and X057 were identified as good parental materials for breeding high yield cultivars of grain, sweet and biomass sorghum, respectively. In order to reconfirm and identify useful breeding materials for this arid region, further experimental research needs to be conducted.
    Numerical simulation and analysis of saltwater intrusion lengths in the Pearl River Delta, China
    Zhang, W. ; Feng, H. ; Zheng, J. ; Hoitink, A.J.F. ; Vegt, M. van der; Zhu, Y. ; Cai, H. - \ 2013
    Journal of Coastal Research 29 (2013)2. - ISSN 0749-0208 - p. 372 - 382.
    partially stratified estuary - salt intrusion - mixed estuary - salinity - discharge - dynamics - flow
    In recent years, large-scale saltwater intrusion has been threatening the freshwater supply in the metropolitan cities surrounding the Pearl River delta (PRD). Therefore, a better understanding of the saltwater intrusion process in this region is necessary for local water resource management. In this paper, a one-dimensional flow and salinity model of the Pearl River networks was established to improve our understanding of saltwater intrusion problems in deltas. The model has high spatial resolution, discretized into 328 reaches and 5108 cross-sections, and the time step is 300 seconds for the hydrodynamic model and 30 seconds for the salinity model on the basis of the Courant–Friedrichs–Lewy condition. The model is calibrated and validated against the field measurements of the water surface elevation, discharge, and salinity at around 40 gauges in 2005 and 2001, respectively. The estimated results are in reasonable agreement with the observational data, suggesting that the model is sufficiently robust to simulate the movement of flow and salinity in the Pearl River networks. The simulated 0.5 parts per thousand salinity isohaline in the Pearl River networks displays a shape similar to “S” and slanting to the right, indicating that the maximum saltwater intrusion length occurs at the Humen outlet. In 2005, the saltwater intrusion lengths intruded far upstream at an average length of 32.4 km from the eight outlets, which is nearly two times that in 2001. Four representative upstream flows were also simulated to acquire quantitative knowledge of the response of the saltwater intrusion to discharges. Finally, historical data were collected to compare the situations of saltwater intrusion in the river networks in the 1960s and 2005. The result implies that the abrupt change in topography due to intensive dredging campaigns in the river networks is probably the most crucial factor leading to the saltwater intrusion outbreaks in large areas of the PRD in recent years
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