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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    Measurements of transcripts, proteome and metabolite profiles
    Peters, Sander - \ 2017
    Fuel4Me - 7
    biobased economy - biobrandstoffen - algen - algenteelt - oliën - biobased economy - biofuels - algae - algae culture - oils
    The work described for this deliverable was carried out by DLO-PRI, in collaboration with WU, and aim ed to understanding lipid production in Phaeodactylum tricornutum . By means of transcriptome, proteome and metabolome analyses we aimed to provide insight into the one step lipid production performed by partner WU. Cultivation conditions were chosen to steer lipid profile towards most suitable composition for biofuel production.
    Structuring oil by protein building blocks
    Vries, Auke de - \ 2017
    Wageningen University. Promotor(en): Erik van der Linden, co-promotor(en): Elke Scholten. - Wageningen : Wageningen University - ISBN 9789463430760 - 167
    gelation - gels - proteins - mechanical properties - oils - solidification - gelering - gels - eiwitten - mechanische eigenschappen - oliën - hardwording

    Over the recent years, structuring of oil into ‘organogels’ or ‘oleogels’ has gained much attention amongst colloid-, material,- and food scientists. Potentially, these oleogels could be used as an alternative for saturated- and trans fats in food products. To develop oleogels as a suitable replacement for saturated fats, the requirements go beyond merely providing a solid appearance to an otherwise liquid oil. For food applications, the gelator should be a well-known ingredient for food manufacturers, have a good nutritional value, and contribute to ‘clean labelling’. Proteins meet all these requirements and could therefore be of high potential. The general concept of protein-based oil gelation fits well into the growing general interest to reduce solid fats from food products along with increase in flexibility in terms of choice of ingredients. In this thesis, the suitability of proteins as a structuring agent for liquid oil was investigated and the rheological behaviour was described. To create protein oleogels, heat-set whey protein gels and protein aggregates, or ‘building blocks’, are created in an aqueous environment. Then, the aqueous phase is exchanged for a liquid oil phase via an intermediate solvent. It was show that by using this procedure, the created protein building blocks are highly efficient in creating oleogels. It is encouraging to see that the interactions between proteins can be altered by simple changes to the system, such as changing the oil type, water addition, or applying a heat treatment. This leads to the possibility to effectively and substantially tune the rheological properties of the final oleogel, such as its gel strength or yielding behaviour.

    Oil slick fate in 3D : predicting the influence of (natural and chemical) dispersion on oil slick fate
    Zeinstra-Helfrich, Marieke - \ 2016
    Wageningen University. Promotor(en): Tinka Murk, co-promotor(en): W. Koops. - Wageningen : Wageningen University - ISBN 9789462579279 - 174
    oil spills - pollution - adverse effects - oils - dispersion - models - thickness - olieverontreinigingen - verontreiniging - nadelige gevolgen - oliën - dispersie - modellen - dikte

    In certain conditions, (part of) an oil spill can disappear from the water surface through a process called natural dispersion. One available oil spill response option is to enhance this process by addition of dispersants (chemical dispersion). An informed decision for such response requires insight in the oil slick size WITH and WITHOUT treatment. This thesis aims to enable such assessment of net effectiveness, by providing a strategy for modelling the dispersion process.

    A plunging jet test was developed for investigating entrainment and droplet breakup. Using this set up the relevance of oil layer thickness was proven and an algorithm to model droplet sizes of dispersed oil was defined. The findings were applied in a model simulating dispersion and resurfacing as well as the wind-driven differential transport between the floating slick and suspended droplets. The simulation outputs help assess the added value (or not) of dispersant application in reducing the surface oil slick size for different oil types and conditions.


    An economic model for offshore cultivation of macroalgae
    Dijk, Wim van; Schoot, Jan Rinze van der; Edwards, Maeve ; Queguineur, Benoit ; Champenois, Jennifer ; Mooney, Karen ; Barrento, Sara - \ 2015
    Swansea : Swansea University - 21
    biobased economy - biomass - biofuels - algae - algae culture - oils - seaweeds - seaweed culture - biobased economy - biomassa - biobrandstoffen - algen - algenteelt - oliën - zeewieren - zeewierenteelt
    Algae biomass is considered as a potential non-fossil source of raw materials to produce fuel, feed, chemicals and materials. For this purpose microalgae as well as macroalgae can be used, and in this report we focus on the latter. More than 99% of the world production of aquatic plants is produced in Asia (FAO 2012, Table 1). From the remaining 1% about 4% is cultivated in Europe. Important European countries with commercial seaweed cultivation are Denmark, Ireland and France. Depending on their pigmentation seaweed species are commonly grouped in brown, red and green seaweeds.
    Strain improvement of oleaginous microalgae
    Jaeger, L. de - \ 2015
    Wageningen University. Promotor(en): Gerrit Eggink; Rene Wijffels, co-promotor(en): Dirk Martens. - Wageningen : Wageningen University - ISBN 9789462574847 - 200
    algen - biomassa - oliën - productiviteit - opbrengsten - transcriptomica - triacylglycerol lipase - bioreactoren - transformatie - mutanten - algenteelt - biomassa productie - algae - biomass - oils - productivity - yields - transcriptomics - triacylglycerol lipase - bioreactors - transformation - mutants - algae culture - biomass production

    The increasing world population and living standards have enlarged the demand for food, feed, and for chemicals. Traditional fossil fuel based commodities need to be replaced, not only because these resources are finite, but also to relieve the impact of carbon emission and pollution, resulting from fossil fuel derived processes. Much attention is on using plants to produce sustainable, renewable alternatives to petrochemical based processes. Palm oil is the crop with the highest lipid yield known today, but the production of palm oil causes deforestation on a large scale. Microalgae are a promising platform for the production of sustainable commodity products. A commodity product that can be produced in microalgae is triacylglycerol (TAG). The TAG molecules that are accumulated in microalgae are comparable to the TAG profiles of commonly used vegetable oils, and can directly be applied for edible oil as well as for biodiesel production. Currently, microalgae derived products have proven to be functional and a potential replacement for conventional crops. However, microalgae derived products, especially TAGs, are not economically feasible yet. In order to make microalgal derived products a reality we need to decrease the production costs by smart technological solutions, biological understanding and metabolic engineering.

    To get more insight in the lipid accumulation mechanism of microalgae, and to define targets for future strain improvement strategies, transcriptome sequencing of the oleaginous microalgae Neochloris oleoabundans was done. This oleaginous microalga can be cultivated in fresh water as well as salt water. The possibility to use salt water gives opportunities for reducing production costs and fresh water footprint for large scale cultivation.

    In chapter 2 the lipid accumulation pathway was studied to gain insight in the gene regulation 24 hours after nitrogen was depleted. Oil accumulation is increased under nitrogen depleted conditions in a comparable way in both fresh and salt water. The transcriptome sequencing revealed a number of genes, such as glycerol-3-phosphate acyltransferase and via glycerol-3-phosphate dehydrogenase, that are of special interest and can be targeted to increase TAG accumulation in microalgae. NMR spectroscopy revealed an increase in proline content in saline adapted cells, which was supported by up regulation of the genes involved in proline biosynthesis. In addition to proline, the ascorbate-glutathione cycle seems to be of importance for successful osmoregulation by removal of reactive oxygen species in N. oleoabundans, because multiple genes in this pathway were upregulated under salt conditions. The mechanism behind the biosynthesis of compatible osmolytes in N. oleoabundans can be used to improve salt resistance in other industrially relevant microalgal strains.

    Another very promising candidate for TAG production is the oleaginous green microalga Scenedesmus obliquus.

    In chapter 3, UV mutagenesis was used to create starchless mutants, since no transformation approach was available for this species, due to its rigid and robust cell wall. All five starchless mutants that were isolated from over 3500 screened mutants, showed an increased triacylglycerol productivity. All five starchless mutants showed a decreased or completely absent starch content. In parallel, an increased TAG accumulation rate was observed for the starchless mutants and no substantial decrease in biomass productivity was perceived. The most promising mutant (Slm1) showed an increase in TFA productivity of 41% at 4 days after nitrogen depletion and reached a TAG content of 49.4% (%CDW).

    In chapter 4 the Slm1 strain was compared to the wild type strain using photobioreactors. In the wild type, TAG and starch accumulated simultaneously during initial nitrogen starvation, and starch was subsequently degraded and likely converted into TAG. The Slm1 did not produce starch and the carbon and energy acquired from photosynthesis was partitioned towards TAG synthesis. This resulted in an increase of the maximum TAG content in Slm1 to 57% (%CDW) compared to 45% (%CDW) in the wild type. Furthermore, it increased the maximum yield of TAG on light by 51%, from 0.144 in the wild type to 0.217 g TAG mol-1 photon-1 in the Slm1 mutant. No differences in photosynthetic efficiency between the Slm1 mutant and the wild type were observed, indicating that the mutation specifically improved carbon partitioning towards TAG and the photosynthetic capacity was not affected.

    To identify the mutation that caused the starchless phenotype of Slm1 the transcriptome of both the wild type and the Slm1 mutant was sequenced as described in chapter 5. A single nucleotide polymorphism (SNP) was discovered in the small subunit of the starch biosynthesis rate-controlling enzyme ADP-glucose pyrophosphorylase, which resulted in the introduction of a STOP codon in the messenger RNA of the enzyme. The characterization of the mutation increases the understanding of carbon partitioning in oleaginous microalgae, leading to a promising target for future genetic engineering approaches to increase TAG accumulation in microalgae.

    To use the insight that is gained in chapters 2-5 for metabolic engineering of TAG accumulation and carbon partitioning, a metabolic engineering toolbox is required. However, the development of transformation protocols for new and less well studied industrially relevant microalgae is challenging. In chapter 6, a simple and effective tool for the optimization of transformation protocols is proposed. Optimal voltage settings were determined for five microalgae: C. reinhardtii, Chlorella vulgaris, N. oleoabundans, S. obliquus, and Nannochloropsis sp. This method can be used to speed up the screening process for species that are susceptible for transformation and to successfully develop transformation strategies for industrially relevant microalgae, which lack an efficient transformation protocol.

    In addition to the increase in productivity, improving the quality in terms of fatty acid composition of TAG molecules would be desired as well. For example, the accumulation of stearic acid rich TAG molecules is of special interest, because of the improved structural properties. The lipid accumulating starchless mutant of the model species C. reinhardtii BAFJ5 was used as model species in chapter 7, since genetic toolbox is well established for this species. In this chapter, stearoyl-ACP desaturase (SAD), is silenced by artificial microRNA. The mRNA levels for SAD were reduced after the silencing construct was induced. In one of the strains, the reduction in SAD mRNA resulted in a doubling of the stearic acid content in triacylglycerol molecules, which shows that increasing the fraction of stearic acid in TAG is possible. Furthermore, we hypothesize that in addition to direct conversion in the chloroplast, C. reinhardtii is able to redirect stearic acid from the chloroplast to the cytosol and convert it to oleic acid in the endoplasmic reticulum by stearoyl-CoA desaturase.

    In chapter 8, an outlook is given on microalgal strain improvement strategies for the future, reflecting on the results obtained in this thesis. Also a roadmap is suggested to get genetically modified microalgal derived products on the market. The results presented in this thesis, provide a significant improvement in the understanding of TAG accumulation and carbon partitioning in oleaginous microalgae. Furthermore, improved microalgal strains with increased TAG accumulation or improved TAG fatty acid composition under nitrogen depleted conditions were generated. In addition, an outlook is presented in which the major bottlenecks are presented in future industrial applications of microalgae.

    The dynamics of oil accumulation in Scenedesmus obliquus
    Breuer, G. - \ 2015
    Wageningen University. Promotor(en): Rene Wijffels, co-promotor(en): Dirk Martens; Packo Lamers. - Wageningen : Wageningen University - ISBN 9789462572348 - 268
    algen - stikstof - uithongering - triacylglycerolen - productiviteit - fotosynthese - koolstof - tussenmuren - oliën - algae - nitrogen - starvation - triacylglycerols - productivity - photosynthesis - carbon - partitions - oils

    .Abstract long

    Global demands for food and biofuels increase rapidly, together with an increase of concerns for depleting fossil resources and climate change. New sustainable sources of vegetable oil, from now on referred to as triacylglycerol (TAG), are therefore highly desired. Arable land to produce these TAGs is however limited. Microalgae have the potential to achieve much higher TAG productivities than commonly used terrestrial plants and can be cultivated on non-arable land. Microalgae are therefore often considered as a promising alternative natural-source of TAGs. Microalgae can accumulate up to 50% of their weight as TAGs, but only do so in response to nitrogen starvation. At the same time, nitrogen starvation also affects many other cellular processes, including photosynthesis. At the start of the work presented in this thesis, little was known about the quantitative aspects of photosynthesis and TAG production during nitrogen starvation. This contributed to a large uncertainty in what could be expected from microalgae. This thesis therefore provides a quantitative understanding of the microalgal response to nitrogen starvation, that can be used to understand and optimize TAG production.

    The differences between microalgae species in their response to nitrogen starvation are characterized. It was found that the difference in the response to nitrogen starvation between microalgae could be characterized in 1) how long the species could retain their photosynthetic efficiency during nitrogen starvation, 2) how much the species could in increase in biomass concentration in the absence of a nitrogen source, and 3) which fraction of the newly made biomass constitutes of TAG. The microalga species S. obliquus was chosen as the most suitable species for TAG production and used in all further studies.

    It is quantified how process conditions, such as the light intensity, pH, and temperature, influence TAG production during nitrogen starvation in S. obliquus. It was found that TAG could be produced in the ranges pH 5-9, temperature of 20-35°C, and incident light intensity of 200-1500 µmol m-2 s-1. The light intensity did not affect the maximum TAG content. The light intensity did, however, have a major effect on the photosynthetic efficiency. Suboptimal pH values and temperatures resulted in both a reduction in photosynthetic efficiency and reduction in maximum TAG content.

    It was found that during nitrogen starvation, at best approximately half of the biomass produced during nitrogen starvation is TAG. Large amounts of starch were produced simultaneously. This simultaneous starch and TAG production was therefore investigated in more detail. It was investigated how the carbon partitioning ratio (the ratio between fatty acid and starch synthesis rates), and the photosynthetic efficiency during nitrogen starvation, are influenced by the light intensity during nitrogen starvation and by the photoacclimated state at the onset of nitrogen starvation. It was found that the ratio between starch and fatty acid synthesis strongly correlated to the extent of nitrogen starvation, quantified as the biomass nitrogen content. Immediately after nitrogen depletion, mostly starch was made, but when nitrogen starvation progressed, this ratio shifted in favour of fatty acid synthesis. When nitrogen starvation progressed further, only fatty acids were made. Hereafter, the initially accumulated starch was degraded while fatty acid synthesis continued. The effects caused by the photoacclimated state persisted during nitrogen starvation. This did however not affect the photosynthetic efficiency or the carbon partitioning ratio during nitrogen starvation. The light intensity during nitrogen starvation had a major impact on the photosynthetic efficiency, but only a minor impact on the carbon partitioning ratio.

    Because large amounts of starch are produced during nitrogen starvation in wild-type S. obliquus, it is investigated how starchless mutants of S. obliquus can be used to improve TAG production. The carbon-partitioning of the wild-type and the slm1 starchless mutant of S. obliquus are therefore compared. It was found that the starchless mutant diverted all photosynthetic capacity, that was used for starch synthesis in the wild-type, towards TAG synthesis. This resulted in much higher TAG accumulation rates during initial nitrogen starvation. Furthermore, it was found that the efficiency of photosynthesis was not negatively affected in this starchless mutant. Altogether, the TAG yield on light increased by 51%.

    Using these insights, a mechanistic model was developed that describes photosynthesis and carbon partitioning during nitrogen starvation. The model was validated using experimental data from both the wild-type and starchless mutant of S. obliquus. This model was used to investigate how TAG production could be improved by advances in reactor design and strain improvement. Projections are made for productivities that seem feasible when various technologies are implemented in the microalgal cultivation process, using S. obliquus as a case-study.

    Finally, the findings of this thesis are used to evaluate the outcomes of techno-economic and life cycle analysis (LCA) studies that investigated the cost-price and net energy ratio of microalgal products, mostly biodiesel. It was found that the biomass productivity and biochemical composition associated with the cultivation of microalgae are large uncertainties in the input values for these studies. Several scenarios for microalgal cultivation are therefore presented based on the findings of this thesis. For each scenario, productivities, biochemical compositions, and nutrient requirements are provided that can be used as more realistic input values for techno-economic and LCA studies. It was concluded that the TAG productivity is commonly overestimated by 3 to 6-fold. According to these studies, approximately half of the costs and energy are used in the cultivation step. It was therefore concluded that these techno-economic and LCA studies underestimate the cost-price and energy consumption by 2 to 3.5-fold. The future improvements in productivity that might seem feasible according to the model simulations, could potentially improve the productivity such that it approaches the productivity that is commonly assumed as the base-case in current techno-economic and LCA studies. These advances in productivity can help to reduce the cost-price and specific energy consumption, but in addition, a reduction in costs and energy consumption of photobioreactors is needed before microalgal TAG production can be commercialized.

    Dioxin monitoring in fats oils for the feed industry
    Asselt, E.D. van; Sterrenburg, P. - \ 2011
    Wageningen : Rikilt - Institute of Food Safety (Report / RIKILT, Institute of Food Safety 2011.004) - 37
    dioxinen - monitoring - vetten - oliën - veevoederindustrie - analytische scheikunde - productieprocessen - voedselveiligheid - dioxins - monitoring - fats - oils - feed industry - analytical chemistry - production processes - food safety
    The aim of the present project was to determine the most critical steps in the production of fats and oils. First, production processes of vegetables oils, animal fat, fish oil, biodiesel and fat blending were studied and experts from the industry as well as in-house dioxin experts were consulted to identify the most critical steps. Then, monitoring data for vegetable oil, animal fat and fish oil were analysed to determine which products have an increased risk of dioxin contamination.
    Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij: validatie van een oliefilmsysteem op vleeskuikenbedrijven = Measures to reduce fine dust emission from poultry houses: validation of an oil spraying system on broiler farms
    Winkel, A. ; Mosquera, J. ; Harn, J. van; Nijeboer, G.M. ; Ogink, N.W.M. ; Aarnink, A.J.A. - \ 2011
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 392) - 28
    pluimveehouderij - vleeskuikens - fijn stof - emissie - stofbestrijding - meting - oliën - stalklimaat - poultry farming - broilers - particulate matter - emission - dust control - measurement - oils - stall climate
    In this study, the fine dust emission reduction of an oil spraying system was determined through validation measurements on broiler farms.
    Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij : alternatieve manieren van aanbrengen oliefilm op strooisel = Measures to reduce fine dust from poultry houses : alternative ways of oil film application on litter
    Slingerland, R. ; Ooster, A. van 't; Harn, J. van; Hattum, T.G. van; Aarnink, A.J.A. - \ 2010
    Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 348) - 22
    luchtkwaliteit - pluimvee - stofbestrijding - oliën - strooisel - fijn stof - emissie - pluimveehouderij - air quality - poultry - dust control - oils - litter (plant) - particulate matter - emission - poultry farming
    In this desk study alternative ways of oil application to reduce dust emission from poultry houses were investigated.
    Influence of the biobased economy on agricultural markets. Preperation of a modelling approach
    Nowicki, P.L. ; Leeuwen, M.G.A. van; Bos, H.L. ; Chant, L.J. ; Molenveld, K. ; Tabeau, A.A. - \ 2010
    Den Haag : LEI Wageningen UR (LEI report 2010-026) - ISBN 9789086154319 - 57
    biomassa - biomassa productie - oliën - economisch beleid - nederland - biobased economy - marktanalyse - productieprocessen - biomass - biomass production - oils - economic policy - netherlands - biobased economy - market analysis - production processes
    This report is the conclusion of research undertaken to better understand the impact of the developing biobased economy on agricultural land markets. This has involved understanding the true dimension of the biobased economy, namely the large range of products for which a biobased component exists or could exist, and in this regard the likely evolution in the substitution of elements produced from fossil oil. This research is also a first step to determine whether the overall result of the development of the biobased economy will be positive, negative or neutral for the Dutch economy as a whole.
    Identification and analysis of interactions between sea use functions
    Wal, J.T. van der; Quirijns, F.J. ; Leopold, M.F. ; Slijkerman, D.M.E. ; Jongbloed, R.H. - \ 2009
    Den Helder : IMARES (Report / IMARES Wageningen UR C132/09) - 34
    windmolens - parken - noordzee - mariene parken - nutfunctie - zeetransport - oliën - gasproductie - windmills - parks - north sea - marine parks - utility functions - sea transport - oils - gas production
    This report focuses on the interactions both positive and negative between offshore wind energy and the non-wind sea use functions.Some sea use functions can co-exist without substantial negative effects. Other combinations are problematic or even impossible and should be avoided. Therefore the interactions of the sea use functions are of importance.
    Inventory of current and future presence of non-wind sea use functions
    Wal, J.T. van der; Quirijns, F.J. ; Leopold, M.F. ; Slijkerman, D.M.E. ; Jongbloed, R.H. - \ 2009
    Den Helder : IMARES (Report / IMARES Wageningen UR C131/09) - 71
    windmolens - parken - noordzee - mariene parken - nutfunctie - zeetransport - oliën - gasproductie - windmills - parks - north sea - marine parks - utility functions - sea transport - oils - gas production
    In order to assess the suitability of locations on the Central and Southern North Sea for wind parks present sea use functions should also be taken into account. These sea use functions comprise shipping, oil and gas extraction, fisheries, cables and pipelines, military activities, sand extraction, radar interference and nature conservation. IMARES has collected data on these other sea use functions. Data was gathered from several national institutions, with a good deal of help from our project partners in identifying the best available sources.
    Clean technology for the crude palm oil industry in Thailand
    Chavalparit, O. - \ 2006
    Wageningen University. Promotor(en): Arthur Mol; Wim Rulkens. - [S.l.] : S.n. - ISBN 9789085044468 - 229
    milieubeleid - palmoliën - palmoliefabrieksafvalwater - oliën- en vettenindustrie - oliën - afvalwater - afvalwaterbehandeling - waterverontreiniging - verontreinigingsbeheersing - thailand - milieutechnologie - environmental policy - palm oils - palm oil mill effluent - oils and fats industry - oils - waste water - waste water treatment - water pollution - pollution control - thailand - environmental technology
    The aims of this study were to assess the potential contribution of clean(er) technology to improve the environmental performance of the crude palm oil industry inThailand, to analyse implementation barriers for cleaner production in crude palm oil industry, and to provide recommendations for overcoming these barriers. As such the overall aim was to generate ideas for moving the crude palm oil industry towards sustainability.In order to fulfill these research aimsdetailed case studies have been carried out on five palm oil enterprises inThailand. The differences in production processes and location have been taken as core selection criteria.

    The results show thatthe combination of clean technology, industrial ecology and triad network analysis seems to be a good approach in analyzing the environmental impacts from, and environmental improvements of, crude palm oil industry inThailand. Regarding the possibilities of technological improvements of the existing environmental performance of Thai crude palm oil production the application of cleaner production and industrial ecosystem approaches (based on reuse, recycling, and utilization of solids and liquid waste and appropriate energy management) proves to be useful. In this way the goal of almost zero discharge of pollutants (against acceptable costs)for crude palm oil mills situated in a plantation area can be achieved. To move Thai crude palm oil industry towards larger sustainability, the following options can be introduced: application of shell foractivated carbon; use ofempty fruit bunch for mushroom cultivation media; composting; pulp production;MDF (medium-density fiberboard)products; utilizedecanter sludge for animal feed; apply palm oil mill effluent for biogas production; and reuse treated wastewater and bottom sediment from anaerobic ponds for irrigation and as soil conditioner in plantation areas.

    The triad network analysis provides clear understanding of the various barriers met in the implementation of the proposed model of an almost zero waste industrial ecosystem of crude palm oil industry inThailand.Four types of barriers have been distinguished: informational barriers, cooperation barriers, price barriers and human capacity barriers. Following these barriers strategies were developed to cope with each of these barriers.

    Finally,by comparing the performance of the Thai crude palm oil production with the Malaysian palm oil technologies, regulatory framework and institutional arrangements it can be concluded thatThailandcan learn fromMalaysiain how the palm oil industry can move towards sustainable development. Especially legislation, facilitation and financial arrangements around clean technology research and development are key factors in explaining the success of Malaysian best practices.
    Voedingsmiddelenanalyses van de Afdeling Humane Voeiding. Deel 14 Vetzuursamenstelling van frituurvetten en bakkerijmargarines in Nederland in 2004
    Hulshof, P.J.M. ; Kosmeyer, T. ; Siebelink, E. ; Katan, M.B. - \ 2005
    Wageningen : Wageningen Universiteit, Sectie Humane voeding - 18
    voedingsmiddelen - chemische samenstelling - vetten - oliën - bakoliën - bakvetten - boter - margarine - voedingswaarde - voedsel - voedselsamenstelling - kwaliteit - eigenschappen - huishoudens - ziekenhuizen - ziekenhuiscatering - verpleeghuizen - dierlijke producten - ingrediënten - Ghana - Filippijnen - spijsoliën - spijsvetten - institutionele huishoudens - foods - chemical composition - fats - oils - cooking oils - cooking fats - butter - margarine - nutritive value - food - food composition - quality - properties - households - hospitals - hospital catering - nursing homes - animal products - ingredients - Ghana - Philippines - edible oils - edible fats - institutional households
    Minerale olie met pyrethroide helpt tegen virus in Zantedeschia
    Leeuwen, P.J. van; Derks, A.F.L.M. - \ 2004
    BloembollenVisie 2004 (2004)36. - ISSN 1571-5558 - p. 24 - 25.
    bloembollen - zantedeschia - plantenvirussen - epidemiologie - insecten - chemische bestrijding - opbrengsten - emulsies - oliën - pyrethroïden - ornamental bulbs - zantedeschia - plant viruses - epidemiology - insects - chemical control - yields - emulsions - oils - pyrethroids
    Gewasbescherming tegen virus in Zantedeschia: onderzoek door PPO-Bloembollen naar het effect van bespuitingen met minerale olie en pyrethroide op virusaantasting en opbrengst
    Invloed van minerale olie op de bestrijding van Phytophthora infestans in pootaardappelen
    Spits, H.G. ; Bus, C.B. - \ 2003 2003 (2003)15 feb.
    fungiciden - samenstelling - plantenziektebestrijding - vermenging - hulpstoffen - oliën - toepassing - ziektebestrijding - pootaardappelen - akkerbouw - fungicides - composition - plant disease control - mixing - adjuvants - oils - application - disease control - seed potatoes - arable farming
    De invloed van toevoeging van olie aan een fungicide op de werking van het fungicide is afhankelijk van het gebruikte fungicide. Gezamenlijk spuiten van olie en Aviso DF, Curzate M en mogelijk ook Acrobat, verhoogt de curatieve werking van deze fungiciden. Gezamenlijk spuiten van olie en Aviso DF, lijkt de regenvastheid van Aviso DF te verminderen. Bij Acrobat, Curzate M en Tattoo C (1,5 l/ha) is dit niet of nauwelijks het geval. Toevoeging van olie heeft bij Tattoo C geen duidelijk positieve of negatieve invloed op de curatieve werking en regenvastheid van Tattoo C.
    Effects of capillarity and heterogeneity on flow of organic liquid in soil
    Wipfler, E.L. - \ 2003
    Wageningen University. Promotor(en): Sjoerd van der Zee. - Wageningen : Wageningen Universiteit - ISBN 9789058088468 - 147
    bodem - water - oliën - lucht - stroming - waterstroming - luchtstroming - capillaire opstijging - vloeistoffen (fluids) - vloeistoffen (liquids) - modellen - drainage - bodemverontreiniging - soil - water - oils - air - flow - water flow - air flow - capillary rise - fluids - liquids - models - drainage - soil pollution

    Contamination of groundwater by organic liquids, such as gasoline, fuel oils and chlorinated hydrocarbons, forms a serious treat to subsurface water resources. These liquids have a low miscibility with water and move as a discrete liquid phase. A small part of the liquid may dissolve in water and small concentrations can be hazardous for humans. These organic liquids that are also referred to as Non-Aqueous Phase Liquids (NAPLs), may enter the subsurface from a surface spill or a leaking underground pipe or tank. Following a release of sufficient NAPL into the subsurface, NAPL moves through the pores of the soil due to gravitational and capillary forces.

    An enhanced understanding of NAPL flow in the subsurface is needed to identify the critical processes and to determine key parameters in the context of remediation strategies at the field scale. In this thesis we study the behavior of NAPL in soil experimentally and numerically. we focus on the physical aspects of this behavior in the unsaturated part of the soil. This implies that we study the movement, interaction and (re-)distribution in a porous medium (soil) of three fluid phases: water, NAPL and air. The porous medium is water-wet, i.e. water is the wetting fluid, NAPL is the intermediate wetting fluid and air is the non-wetting fluid. This leads to typical three-phase flow behavior. We focus on two problems that are both related to NAPL redistribution into unsaturated soil after a spill: (1) non-drainable residual NAPL and (2) the effect of soil layers on the redistribution of NAPL after a spill. In addition to the introduction, the thesis contains 4 chapters which can be read as self-contained papers.

    Non-drainable residual NAPL is considered to be the NAPL that remains in the capillaries of a porous medium after (gravity) drainage and displacement by air in the presence of residual water in a water-wet soil. Although for remediation strategies it is important to consider this residual NAPL, until now it has not been incorporated into multi phase flow models. In Chapter 2 we develop a constitutive set of saturation-capillary pressure ( Pc-S ) relationships that accounts for non-drainable residual NAPL and that can be used by multi-phase flow models. These relationships are derived from a conceptual pore scale model of which the soil is represented by packed spheres. According to the model, NAPL becomes immobilized (residual) below a certain critical total liquid saturation, S tc. This critical total liquid saturation is porous medium and fluid dependent. Next, the non-drainable residual NAPL saturation increases, when the spreading coefficient of a NAPL decreases. Furthermore, a higher water saturation results in a lower non-drainable residual saturation. Although the model adequately simulated one individual experimental non-drainable residual NAPL data set, this agreement is a shallow basis for assessing whether the model assumptions are valid.

    For this purpose we developed an experiment especially designed to measure three-phase Pc-S relationships and non-drainable residual saturation including independent measurement of the water saturation and pressure. We performed four experiments. We used the fluids water, non-spreading dodecane and air, and sand as the porous medium. The measured non-drainable residual saturation was at most 0.081. From the experimental results no correlation could be observed between the water saturation and the residual NAPL saturation. This might indicate that other mechanisms are involved that are not captured by the constitutive model. In advance of the development of the experimental set up, we searched in the literature for available macroscale experimental data that could provide us with non-drainable residual saturation data that are related to porous medium properties, fluid properties and fluid saturations. After a careful selection we obtained 26 non-drainable residual NAPL data from 9 references. Measured values of non-drainable residual saturation varied between 0.001 and 023. From these data only a relationship between the spreading coefficient Cs , and the residual saturation S or , could be assessed. The value of S or decreases as Cs becomes less negative. It would require a much more comparable description of the different porous media, and a systematic data acquisition for S or as a function of macroscale properties to assess which other factor than the spreading coefficient might be hidden in the data. Changes of porous medium properties such as permeability and porosity across an interface between two soil layers might change the redistribution of NAPL. The mobility may decrease or increase across the interface, which is dependent on the permeability of the layers, the capillarity of the layers and the wetting role that is played by the NAPL with respect to water and air. The effect of these changes have been studied in Chapter 4 and 5.

    In Chapter 4 we focused on the effect of an inclined soil layer with respect to the watertable. Two experiments were performed using a sand filled transparent chamber. The first experiment consisted of Light-NAPL infiltration into a fine sand matrix containing a coarse sand layer and the second experiment consisted of LNAPL infiltration into a coarse sand matrix containing a fine sand layer. The sand was partially saturated with water. We modeled the experiments numerically. The observed LNAPL behavior can be understood by considering that LNAPL might encounter two types of barriers. On the one hand, it may accumulate and spread above a coarse sand layer, that has a low water saturation and, that acts as a capillary barrier for the LNAPL before it may infiltrate into the layer. An on the other hand, it may accumulate and spread above a water saturated fine sand layer that has a high entry pressure for the infiltrating LNAPL. Sensitivity analysis performed with the numerical model shows that the qualitative LNAPL redistribution, in case of inclined layers, is mainly subject to the capillarity contrast between sands.

    In Chapter 5 we considered Dense-NAPL infiltration into a water unsaturated porous medium that consists of two horizontal layers, of which the top layer has a lower intrinsic permeability than the bottom layer. The layer interface forms a barrier to DNAPL flow, which causes the DNAPL to spread out horizontally just above the interface. We have developed an analytical approximation to estimate the DNAPL pressure and saturation and the horizontal extension of the DNAPL plume just above the layer interface at steady state for low water saturations. The analytical approximation shows that the steady state DNAPL infiltration is determined by five dimensionless numbers: the heterogeneity factorg, the Brooks and Corey capillary pressure parameterl, the gravity number Ng , the ratio of the capillary and gravity numbers Nc/Ng , and the critical DNAPL pressure P oc, which indicates the effect of the water saturation on the flow of DNAPL. We compared its predictions with the results of a numerical three-phase flow simulator for a number of parameter combinations. For most of these combinations the analytical approximation predicts the DNAPL pressure and saturation profiles at the interface adequately, although it slightly underestimates the horizontal spreading of the plume at the interface. Using the analytical approximation, we carried out a sensitivity study with respect to the maximum horizontal extension of the plume. The extension of the plumes appears to be highly sensitive to variation of the dimensionless numbers P oc,landg. The extension increases for increasing values oflandgand for decreasing values of P oc.

    Voedingsmiddelenanalyses van de Vakgroep Humane Voeding en Epidemiologie. Deel 12 Retinol en carotenoiden in zuivelproducten
    Hulshof, P.J.H. ; Roekel, T. van; Bovenkamp, P. van de; West, C.E. ; Katan, M.B. - \ 2001
    Unknown Publisher
    voedingsmiddelen - chemische samenstelling - vetten - oliën - bakoliën - bakvetten - boter - margarine - voedingswaarde - voedsel - voedselsamenstelling - kwaliteit - eigenschappen - huishoudens - ziekenhuizen - ziekenhuiscatering - verpleeghuizen - dierlijke producten - ingrediënten - ghana - filippijnen - spijsoliën - spijsvetten - institutionele huishoudens - foods - chemical composition - fats - oils - cooking oils - cooking fats - butter - margarine - nutritive value - food - food composition - quality - properties - households - hospitals - hospital catering - nursing homes - animal products - ingredients - ghana - philippines - edible oils - edible fats - institutional households
    Voedingsmiddelenanalyses van de Vakgroep Humane Voeding. Deel 12 Margarines, spijsvetten, koekjes en snacks-1996
    Hulshof, P.J.H. ; Kosmeijer, T. ; Zock, P.L. ; Bovenkamp, P. van de; Katan, M.B. - \ 1998
    Unknown Publisher
    voedingsmiddelen - voedsel - chemische samenstelling - bakoliën - bakvetten - oliën - boter - margarine - voedingswaarde - voedselsamenstelling - kwaliteit - eigenschappen - huishoudens - ziekenhuizen - vetten - ziekenhuiscatering - verpleeghuizen - ingrediënten - dierlijke producten - ghana - filippijnen - spijsoliën - spijsvetten - institutionele huishoudens - foods - food - chemical composition - cooking oils - cooking fats - oils - butter - margarine - nutritive value - food composition - quality - properties - households - hospitals - fats - hospital catering - nursing homes - ingredients - animal products - ghana - philippines - edible oils - edible fats - institutional households
    Vernevelen van olie: weinig invloed op stofconcentratie
    Doleghs, B. ; Ellen, H.H. - \ 1998
    Praktijkonderzoek voor de Pluimveehouderij 9 (1998)4. - ISSN 0924-9087 - p. 7 - 10.
    pluimvee - pluimveehokken - luchtverontreiniging - stof - verstuiving - water - oliën - hygiëne - landbouwtechniek - persoonlijke hygiëne - poultry - poultry housing - air pollution - dust - atomization - water - oils - hygiene - agricultural engineering - personal hygiene
    Na een inventarisatie naar de verschillende mogelijkheden om de stofconcentratie in de stallucht te verlagen (zie periodiek 97/4), is in een eerste oriënterende proef gekeken naar het effect van het vernevelen van water. Dit bleek slechts een minimaleverlaging te geven. In dit artikel gaan we in op een vervolgproef waarbij olie is toegevoegd aan het water.
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