Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

    Current refinement(s):

    Records 1 - 20 / 43

    • help
    • print

      Print search results

    • export

      Export search results

    Check title to add to marked list
    Agrarisch Waterbeheer in de praktijk : Op zoek naar de gemene deler
    Breman, B.C. ; Linderhof, V.G.M. - \ 2016
    Het Waterschap 2016 (2016)6. - ISSN 1380-4251 - p. 7 - 9.
    waterbeheer - waterschappen - duurzame energie - terugwinning - rioolwaterzuivering - zuiveringsinstallaties - landbouw - innovaties - klimaatadaptatie - stedelijke gebieden - water management - polder boards - sustainable energy - recovery - sewage treatment - purification plants - agriculture - innovations - climate adaptation - urban areas
    In dit themanummer over Green Deals staan de volgende artikelen: 1) Green Deals: Code oranje, blauwe oplossing. 2) Op zoek naar de gemene deler: agrarisch waterbeheer in de praktijk. 3) Kraamkamer van innovatie. 4) Modern aanbesteden is kennis delen: marktvisie waterschappen. 5) De politicus Liesbeth van Tongeren: Niet langer in discussie met klimaatsceptici. 6) Er valt iets te kiezen: waterschappen integreren duurzame energieproductie succesvol in hun kerntaken. 7) Slimmer investeren: Strategisch asset management. 8) Creativiteit op het snijvlak van orde en chaos: Waterschap De Dommel flirt met paradoxen. 9) Open overheid, ook voor waterschappen. 10) Werken aan morgen is gisteren al begonnen: hoe ziet werken voor een waterschap er in 2026 uit?
    Sanitation planning in developing countries : added value of resource recovery
    Kerstens, S.M. - \ 2016
    Wageningen University. Promotor(en): Grietje Zeeman, co-promotor(en): Ingo Leusbrock. - Wageningen : Wageningen University - ISBN 9789462576889 - 316
    sanitation - developing countries - recovery - urban planning - waste water treatment - waste treatment - waste management - environmental technology - volksgezondheidsbevordering - ontwikkelingslanden - terugwinning - stedelijke planning - afvalwaterbehandeling - afvalverwerking - afvalbeheer - milieutechnologie

    Sanitation planning in developing countries: Added value of resource recovery

    Worldwide 2.5 billion people lack access to sanitation. This impacts human live, the environment and represents a loss of valuable resources that can be regained from wastewater. This study shows that resource recovery can be a potential driver to accelerate sanitation. A new sanitation decision framework for policy makers was created and tested in Indonesia.

    The variety of advantages and disadvantages of sanitation interventions complicates the sanitation planning process. Conventional sanitation systems consume energy, chemicals and land or produce a sludge that requires disposal, whereas a range of opportunities exists that enables valorization of resources from our “waste”. To support policy makers in planning sanitation that considers sustainability dimensions (social, environment and economy), a new sanitation framework was developed. This framework resolves trade-offs of sanitation alternatives across spatial and temporal scales in three steps. First, it identifies feasible wastewater and solid waste systems in relation to the type of residential area. Secondly, the anticipated population development, current access and formulated targets are an input to generate the number of required systems, their location and associated implementation costs. The required systems are visualized in geographical maps, while budgets are allocated to responsible implementing institutions. Thirdly, the potential demand from “back-end users” of sanitation products, such as agriculture for compost and phosphorus, aquaculture for produced duckweed and industries for recovered plastic and paper, to substitute conventionally produced materials is determined. These three steps are then combined to quantitatively evaluate the (1) environmental impact, (2) operational costs and benefits, and (3) the potential of selected sanitation alternatives to close material cycles. A case study of the Citarum River was performed in which (monetized) benefits such as health, welfare and revenues from the sale of recovered resources were compared with the costs of different (conventional and resource recovery) sanitation systems. The study showed that the economic Benefit to Cost Ratio (BCR) of resource recovery technologies is bigger than BCR of conventional (low cost) technologies, while improving the water quality. It thus shows that resource recovery is a potential driver to accelerate sanitation development. The framework was illustrated using Indonesia as an example, but its application can benefit the quality of millions of lives worldwide.

    New wastewater treatment concepts towards energy saving and resource recovery
    Khiewwijit, R. - \ 2016
    Wageningen University. Promotor(en): Huub Rijnaarts, co-promotor(en): Karel Keesman; Hardy Temmink. - Wageningen : Wageningen University - ISBN 9789462576407 - 148
    waste water treatment - energy saving - recovery - municipal wastewater - nutrients - volatile fatty acids - afvalwaterbehandeling - energiebesparing - terugwinning - stedelijk afvalwater - voedingsstoffen - vluchtige vetzuren
    At present, conventional activated sludge (CAS) systems are widely applied to treat municipal wastewater. The main advantages of CAS systems are that they are robust and generally produce an effluent quality that meets the discharge guidelines. However, CAS systems cannot be considered sustainable because they consume large amounts of energy (mainly for aeration and sludge treatment), have a high CO2 emission and do no recover a potential resource of water, energy and nutrients nitrogen (N) and phosphorus (P). Therefore, in this thesis new municipal wastewater treatment concepts that combine treatment with recovery of valuable resources and can save considerable amounts of energy were investigated by modelling and experiments.

    Quantitative numerical results showed that the feasibility of two novel wastewater treatment configurations, including combined bioflocculation and anaerobic digestion but with different nutrient removal technologies, i.e. (cold) partial nitritation/Anammox or microalgae treatment, is location dependent. Using Dutch municipal wastewater and climate conditions, the configuration with cold partial nitritation/Anammox is the most promising wastewater treatment concept, because it can: 1) treat wastewater year round; 2) produce an effluent at a quality that meets the discharge guidelines; 3) reduce CO2 emission by 35% compared to the CAS system; 4) achieve a net energy yield up to 0.24 kWh per m3 of wastewater compared to a negative net energy yield of -0.08 kWh per m3 of wastewater for the CAS system; and 5) recover 80% of the sewage P. Additionally, the feasibility of the two configurations was investigated for 16 locations around the globe. The results quantitatively support the pre-assumption that the configuration with (cold) partial nitritation/Anammox is applicable in tropical regions and some locations in temperate regions. The configuration with microalgae treatment is only applicable the whole year round in tropical regions that are close to the equator line. The results also showed that the configuration employing microalgae treatment has an advantage over the configuration employing partial nitritation/Anammox with respect to consumption of aeration energy and recovery of nutrients, but not with respect to area requirements. For a tropical climate country like Thailand, the net energy yield of both configurations is at least a factor 10 higher than the CAS system, while CO2 emission is at least 22% lower.

    In CAS systems energy recovery from wastewater is accomplished by anaerobic digestion of the organic solids in primary and secondary sludge into methane. However, volatile fatty acids (VFA), which are intermediate digestion products, may be preferred over methane, because VFA can be used as starting compounds for a wide range of higher value products. In this thesis the experimental results showed that a combined process with bioflocculation, using a high-loaded membrane bioreactor (HL-MBR) to concentrate sewage organic matter, and anaerobic fermentation, using a sequencing batch reactor to produce VFA is technologically feasible. An HL-MBR operated at a hydraulic retention time (HRT) of 1 hour and a sludge retention time (SRT) of 1 day resulted in very good performance, because as high as 75.5% of the sewage COD (chemical oxygen demand) was diverted to the concentrate and only 7.5% was mineralized into CO2. It was also found that 90% of the sewage NH4-N and PO4-P were conserved in the HL-MBR permeate, which can be reused as irrigation water as it is free from solids and pathogens.

    During anaerobic fermentation of the HL-MBR concentrate at an SRT of 5 days, 35°C and without pH control, methane production was inhibited, but incomplete solids degradation mainly limited the VFA production as only 15% of the sewage COD was converted to VFA. Thus, the VFA yield needed to be increased. It was hypothesized that high pH (pH 8–10) fermentation combined with a long SRT, allowing for sufficient solubilization of solids and colloidal COD, can improve the VFA yield. In the current study, it was found that application of a pH shock of 9 in the first 3.5 hours of a sequencing batch cycle followed by a pH uncontrolled phase for 7 days gave the highest VFA yield of 440 mg VFA-COD/g VSS and this was equivalent to 26% of the sewage COD. This yield was much higher than at fermentation without pH control or at a constant pH between 8 and 10. The high yield in the pH 9 shock fermentation could be explained by: 1) a reduction of methanogenic activity; or 2) a high degree of solids degradation; or 3) an enhanced protein hydrolysis and fermentation. This study also demonstrated that the VFA yield can still be further optimized by fine-tuning pH levels and longer operation, possibly with fermentative microorganisms adapted to a high pH that are commonly found in nature. This would further increase VFA yield to 33% of the sewage COD.
    Biorefinery : recovery of valuable biomolecules
    Eppink, M.H.M. - \ 2015
    Wageningen : Wageningen University - ISBN 9789462573789 - 28
    biorefinery - recovery - biomass - biofuels - separation technology - biomass conversion - biomass cascading - biobased economy - bioraffinage - terugwinning - biomassa - biobrandstoffen - scheidingstechnologie - biomassaconversie - biomassa cascadering - biobased economy
    Inaugural speech Wageningen University, 23 April 2015
    Products, by-products and recovered secondary materials from processed animal manure
    Ehlert, P.A.I. ; Schoumans, O.F. - \ 2015
    Wageningen : Alterra, Wageningen-UR (Alterra report 2668) - 29
    animal manures - manure treatment - byproducts - fertilizers - nitrates - recovery - dierlijke meststoffen - mestverwerking - bijproducten - kunstmeststoffen - nitraten - terugwinning
    Technieken om dierlijke mest en andere biomassa stromen te verwerken om de waardevolle componenten te benutten krijgen steeds meer de aandacht nu makkelijk winbare ertsen en energiebronnen van fossiele herkomst gelimiteerd raken en er meer en meer aandacht gegeven wordt aan terugdringen van uitstoot van CO2 van fossiele bronnen. Producten van dierlijke mest ressorteren onder diverse stelsels van regels van de Europese Unie. Deze stelsels zijn complex en bevorderen daardoor niet altijd een hergebruik. Dit rapport beschrijft kort welke technologieën er zijn om dierlijke mest te verwerken en welke producten daaruit resulteren. Vervolgens worden Europese wettelijke bepalingen beschreven die op deze producten van toepassing zijn. Deze bepalingen vragen aanpassing aan de nieuwe technologieën voor verwerking van dierlijke mest. Het rapport geeft daarvoor aanbevelingen.
    Bio-induced solid selenium for recovery from water
    Hageman, S.P.W. - \ 2015
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): Renata van der Weijden; Fons Stams. - Wageningen : Wageningen University - ISBN 9789462575103 - 156
    selenium - waste water - waste water treatment - recovery - toxicity - bioreactors - selenium - afvalwater - afvalwaterbehandeling - terugwinning - toxiciteit - bioreactoren

    Selenium in the form of selenate or selenite in wastewater needs to be removed due to its potential toxicity in the environment. Also, selenium is a valuable element that is used in several industries and current selenium resources are likely to be exhausted in less than 50 years. Waste streams containing selenium can therefore be used as a source of selenium. This requires conversion of the selenium in wastewater into a form that can be recovered. Biologically induced selenate reduction to recoverable selenium has the advantage that it uses the selective reduction capacities of biomass and a renewable electron donor.

    To improve the recoverability of selenium the conversion of selenate to selenite was seen as an interesting opportunity. Selenite is more reactive than selenate and can be removed in a second step. As described in Chapter 2, it proved possible to convert selenate to mainly selenite at a low electron donor concentration.

    Another method which is reviewed in this thesis is direct biological reduction of selenate to elemental selenium. After reduction the solids can be removed by a liquid solid separation process. Previously amorphous selenium particles were produced, which hampered recovery. In this research it is demonstrated that at a higher temperature, around 40 - 50°C, and at a higher pH, around pH 8 - 9, a more hexagonal selenium structure can be produced (Chapter 3). Crystalline acicular selenium particles of different sizes were thus obtained. This implies that selenium particles formation can be controlled and that selenium particles can grow. Large selenium particles make the separation process economic.

    To grow larger selenium particles, a long-term experiment was performed at 50°C (Chapter 4). The reduction rate was poor, but selenium acicular particles were produced. These particles were also detected as clusters. These clusters open up new recovery opportunities. With Eerbeek sludge the optimal conditions for selenate conversion are around pH=7 and 30°C. To enlarge the selenium particles it is strongly recommended to use a different sludge since the optimal conditions with Eerbeek sludge do not match the conditions needed for acicular particle formation.

    When selenate is converted to selenite, the selenite can be precipitated by sulphide to form selenium sulphide. Emmtec sludge was used to reduce the sulphur compounds to sulphide, leaving selenium as the sole remaining element. This process was performed at T=30°C and a pH between 6 and 7. The selenium thus recovered had a crystalline hexagonal structure (revealed by x-ray diffraction) and the particles were as large as 125µm3.

    Future research on the two routes that are explored in this thesis can give insights into selenium reduction mechanisms and the formation of large selenium particles. The recoverability of biological selenium particles has also been improved (as discussed in this thesis). In conclusion, this thesis has resulted in a new, bio-selective, renewable selenium recovery method via selenium sulphide.

    Mest vol verwaarden? Wat kan raffinage betekenen?
    Starmans, D.A.J. ; Buisonjé, F.E. de; Dijk, W. van; Haan, J.J. de; Timmerman, M. ; Visser, C.L.M. de - \ 2015
    Lelystad : WUR/ACRRES (Rappot / PPO-AGV 658) - 41
    mestverwerking - samenstelling - bioraffinage - economische haalbaarheid - haalbaarheidsstudies - terugwinning - materialen uit biologische grondstoffen - manure treatment - composition - biorefinery - economic viability - feasibility studies - recovery - biobased materials
    Het doel van deze studie was te inventariseren welke waardevolle stoffen uit mest gewonnen kunnen worden en wat de potentie is in technologie en markt om deze te verwaarden. De inhoud van mest kan onderverdeeld worden in de volgende hoofdcategorieën: organische stof, mineralen, zware metalen, aminozuren, vluchtige vetzuren, antibiotica, hormonen. Via literatuuronderzoek is de samenstelling van elke categorie uiteen gesplitst in de verschillende stoffen met daarbij het gemiddelde gehalte van de betreffende stof in mest. Voor elke stof is de range in marktprijs nagegaan en aan de hand van het gehalte en marktprijs is de intrinsieke waarde van elke stof in de mest bepaald. Per hoofdcategorie van stoffen valt aan de hand van de waarde van de componenten te voorspellen of het mogelijk is om een sluitende business case te maken.
    Hoeveel is onze poep eigenlijk waard?
    Vet, L.E.M. - \ 2015
    Universiteit van Nederland
    afvalwaterbehandeling - waterzuivering - rioolwater - mestvergisting - geneesmiddelen - fosfaat - terugwinning - algenteelt - helofytenfilters - feces - nieuwe sanitatie - biobased economy - lesmaterialen - waste water treatment - water treatment - sewage - manure fermentation - drugs - phosphate - recovery - algae culture - artificial wetlands - faeces - new sanitation - biobased economy - teaching materials
    Prof. dr. Louise Vet van Wageningen UR heeft een donkerbruin vermoeden dat we waardevolle stoffen door het toilet spoelen. Sterker nog: ze weet het zeker. Voedingsstoffen, zelfs medicijnen: In dit college vertelt ze hoe we met algen en nieuwe technologie kostbaar spul uit ons bruine spul kunnen halen. Louise Vet is hoogleraar Evolutionaire Ecologie aan de Universiteit Wageningen en directeur van het Nederlands Instituut voor Ecologie. Professor Vet is een vrouw met een missie: een zo duurzaam mogelijke wereld realiseren. Zo gaf ze zelf het goede voorbeeld door het kantoorcomplex en lab waar zij haar onderzoek doet geheel via de cradle-to-cradle filosofie in te richten.
    Microalgae cultivation for nutrient recovery from human urine
    Tuantet, K. - \ 2015
    Wageningen University. Promotor(en): Grietje Zeeman, co-promotor(en): Hardy Temmink; Marcel Janssen. - Wageningen : Wageningen University - ISBN 9789462572676 - 174
    afvalwaterbehandeling - afvalwateraquacultuur - urine - algenteelt - terugwinning - fosfor - stikstof - fotobioreactoren - biomassa productie - biobased economy - nieuwe sanitatie - waste water treatment - wastewater aquaculture - urine - algae culture - recovery - phosphorus - nitrogen - photobioreactors - biomass production - biobased economy - new sanitation
    Nieuwe, brongerichte sanitatieconcepten krijgen meer en meer aandacht en laten een groot potentieel zien voor het terugwinnen van nutriënten, organische stof en water, en voor de productie van energie. Verschillende van deze nieuwe sanitatieconcepten zijn geïmplementeerd in landen zoals Nederland, Duitsland, Zweden en China. Van de beschikbare terugwinningstechnieken voor urine is er geen één die zowel stikstof als fosfor kan terugwinnen. Dat is wel mogelijk door algen te kweken op urine, vanwege de hoge N:P ratio in de algen biomassa. Tot nu toe zijn er maar een beperkt aantal studies uitgevoerd gericht op het gebruik van urine voor het kweken van microalgen. Microalgenkweek heeft een groot potentieel voor de behandeling van urine in vergelijking met de meeste andere technieken die op dit moment al commercieel beschikbaar zijn. Een model system voor Nederlandse omstandigheden werd geëvalueerd, gebruik makend van parameterwaarden uit de experimenten beschreven in dit proefschrift als wel uit de literatuur. Dit heeft aangetoond dat in Nederland microalgenkweek mogelijk is van de late lente tot laat in de zomer.
    Selective short chain carboxylates production by mixed culture fermentation
    Arslan, D. - \ 2014
    Wageningen University. Promotor(en): Cees Buisman, co-promotor(en): H. De Wever; Kirsten Steinbusch. - Wageningen : Wageningen University - ISBN 9789462571228 - 211
    fermentation - carboxylic acids - recovery - waste utilization - technology - fermentatie - carbonzuren - terugwinning - afvalhergebruik - technologie


    Surfactants are produced and used in the formulation of many different commercial products. After use, these compounds end up in wastewater treatment plants (WWTPs) or in the environment. Although many surfactants can be degraded in aerobic conditions, anaerobic conditions are also common in Nature and in WWTPs. For achieving nutrients removal from wastewater, biological removal of nitrogen and phosphorus can be performed in a WWTP using the anaerobic-anoxic-aerobic (A2/O) concept. Using the A2/O process sequence, surfactants can be degraded anaerobically before reaching the aerobic compartment. In the anoxic compartment, facultative anaerobic bacteria can degrade surfactants by using nitrate/nitrite as electron acceptor. However, not much is known about surfactant-degrading denitrifying bacteria. In this thesis, Pseudomonas stutzeri strain SN1 and Pseudomonas nitroreducens strain SN2 were isolated from activated sludge of a WWTP with the A2/O process, using the anionic surfactant sodium dodecyl sulfate (SDS) as sole carbon and energy source. Both strains were able to completely degrade SDS coupled to nitrate reduction to dinitrogen gas (Chapter II).

    In the A2/O process, the diversity of bacterial communities involved in the degradation of surfactants may differ between anoxic and oxic compartments, where two different electron acceptors are involved. Surfactants can directly affect the biological activity of microorganisms present in WWTPs and disturb the treatment efficiency. In this way, increased concentrations of surfactants may give rise to a different bacterial diversity selection in anaerobic, anoxic and oxic conditions. The degradation of the anionic surfactant sodium lauryl ether sulfate (SLES) in aerobic conditions is known, but not in denitrifying conditions. In this thesis, the bacterial diversity of enrichments cultures able to degrade different concentrations of SLES in anoxic and aerobic conditions was determined. Aeromonas hydrophila strain S7, Pseudomonas stutzeri strain S8 and Pseudomonas nitroreducens strain S11 were isolated from anoxic enrichments. Comamonas testosteroni strain S13 and Acinetobacter sp. S15 were isolated from aerobic enrichments (Chapter III). SLES initial degradation steps by pure bacterial cultures were previously investigated, but much is still unknown about how the cleavage of ether bonds from chemical compounds is catalyzed by bacterial enzymes. Aeromonas hydrophila strain S7, Pseudomonas stutzeri strain S8 and Pseudomonas nitroreducens strain S11 are able to use SLES in anoxic conditions coupled to nitrate reduction (Chapter III). SLES degradation in anoxic conditions was compared between the three strains. P. nitroreducens strain S11 was found to be the best SLES degrader in anoxic conditions and also to be an excellent aerobic SLES degrader (Chapter IV). Sulfatases and ether cleaving enzymes were probably used by P. nitroreducens strain S11 in both conditions, although differences between SLES degradation in aerobic and anoxic conditions indicated that ether cleavage and following SLES complete degradation is faster under aerobic conditions.

    Although surfactants can be toxic to microorganisms, surfactant-degrading bacteria are known to be resistant to high surfactants concentration, in aerobic conditions. This was not previously investigated using surfactant-degrading denitrifying bacteria. Surfactant-resistant bacteria, with the ability to couple surfactant degradation to nitrate reduction, can be very useful for degrading the surfactants arriving to the anoxic compartments of a WWTP at high concentration. In this thesis, high concentrations of SDS and SLES were used to investigate the effect of these on SDS/SLES-degrading bacteria (P. stutzeri strain SN1, P. nitroreducens strain SN2, P. stutzeri strain S8 and P. nitroreducens strain S11), under anoxic conditions (Chapter V). P. stutzeri strain SN1 was inhibited by increasing SDS and SLES concentrations, after degrading a certain amount of the surfactants. Overall, P. nitroreducens strains showed to be more resistant to high surfactant concentrations compared to P. stutzeri strains. Nevertheless, high concentrations of SDS and SLES did not inhibit growth and nitrate reduction ability of any of the tested Pseudomonas sp..

    Protein domains represent the evolutionary conserved autonomously folding functional building blocks of the proteins. Prediction of protein domains from genomes can be used for species classification and validation of known physiological abilities. P. nitroreducens are facultative anaerobic bacteria from the P. aeruginosa group, which can degrade complex compounds. P. nitroreducens DSM 14399T shares with P. nitroreducens strain SN2 the ability for SDS degradation in anoxic conditions. For increasing the insight into P. nitroreducens DSM 14399T phylogenetic classification and physiological properties (e.g. SDS degradation) its genome was sequenced, annotated and compared to other Pseudomonas spp. genomes. This was performed by comparing functional profiles, based on protein domains presence or absence, with physiological data (Chapter VI). Functional profile comparison confirmed P. nitroreducens classification. Protein domain analysis and genes annotation validated SDS degradation by P. nitroreducens DSM 14399T. This study showed that protein domains prediction and functional profiles comparison can be used for studying and comparing different Pseudomonas species at the physiological level.

    Phosphate and organic fertilizer recovery from black water
    Tervahauta, T.H. - \ 2014
    Wageningen University. Promotor(en): Cees Buisman; Grietje Zeeman, co-promotor(en): L. Hernandez Leal. - Wageningen : Wageningen University - ISBN 9789462570931 - 156
    afvalwater - fosfaten - afvalwaterbehandeling - organische meststoffen - terugwinning - anaërobe behandeling - zware metalen - hergebruik van water - waste water - phosphates - waste water treatment - organic fertilizers - recovery - anaerobic treatment - heavy metals - water reuse
    In this thesis the integration of treatment systems for black and grey water was investigated to improve resource recovery within source-separated sanitation concepts. Special focus was set on phosphate and organic fertilizer recovery from vacuum collected black water. Currently, the soil application of black water sludge is prohibited in the Netherlands due to elevated heavy metal concentrations.
    Transition or stagnation? : everyday life, food security and recovery in post-conflict northern Uganda
    Wairimu, W.W. - \ 2014
    Wageningen University. Promotor(en): Thea Hilhorst, co-promotor(en): I. Christoplos; Maja Slingerland. - Wageningen : Wageningen UR - ISBN 9789462570276 - 188
    conflict - middelen van bestaan - voedselzekerheid - terugwinning - uganda - minst ontwikkelde landen - oost-afrika - conflict - livelihoods - food security - recovery - uganda - least developed countries - east africa

    This thesis seeks to analyse whether and in what way institutional reconstruction meets the needs, and fits the context, of the population they are meant to serve. Often we talk about post-conflict societies as ‘being in transition’ or ‘moving out of crisis’, and this thesis basically asks the question: ‘transition to whatand movement to where’? The thesis is based predominantly on ethnographic work undertaken in Pader district, northern Uganda between 2010 and 2012 where stimulation of the agricultural sector has been pursued as a way to consolidate peace and promote recovery after years of displacement.

    The thesis finds that the processes and dynamics of transition in northern Uganda involve: (1) Messy transitions between humanitarian services and state-led market ‘modernisation’(2) an attempt to bridge policy and practice mismatches – a process through which institutional relations or new institutions evolve out of the process of recovery and reconstruction (3) that the transition and recovery in northern Uganda relates to the linking of Relief Rehabilitation and Destitution, rather than linking to Development. Assets erode to such an extent that development is not an achievable goal for many of those formerly displaced. Many people see their ‘normality’ becoming a state of ‘Destitution’ instead of ‘Development’.

    Explorative study of phosphorus recovery from pig slurry : laboratory experiments
    Schoumans, O.F. ; Ehlert, P.A.I. ; Nelemans, J.A. ; Doorn-van Tintelen, W. van; Rulkens, W.H. ; Oenema, O. - \ 2014
    Wageningen : Alterra, Wageningen-UR (Alterra report 2514) - 46
    dierlijke meststoffen - varkensdrijfmest - mestverwerking - terugwinning - fosfor - fosfaat - laboratoriumproeven - milieubeleid - animal manures - pig slurry - manure treatment - recovery - phosphorus - phosphate - laboratory tests - environmental policy
    Here, we report on laboratory experiments with the aim to explore cheap and innovative techniques. The main focus of the experiments was to lower the P-content in pig slurry with 25%. In that case, in principle all manure produced in the Netherlands can be applied on agricultural land in The Netherlands itself, including the organic matter and other nutrients in the manure. The results show that with physical and chemical treatment techniques 25% of the phosphate can rather easily be recovered from the solid or liquid fractions of the pig slurry. The costs of chemicals depend highly on the buffer capacity of the studied (n=3) pig slurries, and are less than 5 € per ton pig slurry.
    Nutrient removal and microalgal biomass production on urine in a short light-path photobioreactor
    Tuantet, K. ; Temmink, B.G. ; Zeeman, G. ; Janssen, M.G.J. ; Wijffels, R.H. ; Buisman, C.J.N. - \ 2014
    Water Research 55 (2014). - ISSN 0043-1354 - p. 162 - 174.
    waterzuivering - bioreactoren - fosfaten - stikstof - terugwinning - nieuwe sanitatie - biomassa productie - urine - algenteelt - biobased economy - water treatment - bioreactors - phosphates - nitrogen - recovery - new sanitation - biomass production - urine - algae culture - biobased economy - chlorella-sorokiniana - spirulina-platensis - anaerobic treatment - black water - phosphorus - management - efficiency - vulgaris - biofuels
    Due to the high nitrogen and phosphorus content, source-separated urine can serve as a major nutrient source for microalgae production. The aim of this study was to evaluate the nutrient removal rate and the biomass production rate of Chlorella sorokiniana being grown continuously in urine employing a short light-path photobioreactor. The results demonstrated, for the first time, the possibility of continuous microalgae cultivation in human urine. The lowest dilution factor successfully employed was a factor of 2 (50% v/v urine). Microalgae dominated a smaller bacterial population and were responsible for more than 90% of total nitrogen and phosphorus removal.
    Numerical and experimental design of ultrasonic particle filters for water treatment
    Cappon, H.J. - \ 2014
    Wageningen University. Promotor(en): Gerrit van Straten, co-promotor(en): Karel Keesman. - Wageningen : Wageningen University - ISBN 9789461738592 - 202
    waterzuivering - terugwinning - ultrasone behandeling - geluidsleer - scheidingstechnologie - wiskundige modellen - water treatment - recovery - ultrasonic treatment - acoustics - separation technology - mathematical models

    Due to limited water resources available in the world and the ever growing world population, there is an increasing need for water recycling, recovery and multi-sourcing strategies. One of the new physical process technologies being investigated for water purification and/or constituent recycling is ultrasonic particle separation. This technology is especially interesting for harvesting particles with an almost neutral buoyancy. An ultrasonic particle filter does not use a filter medium, like sand or a membrane, but filters on a basis of acoustic forces in ultrasonic standing waves, which are able to immobilise particles in flowing water.

    The objective of this study was to develop an ultrasonic separation device for particle recovery and water purification. This separator should be fit for industrial applications treating cubic meters of water per hour. In order to reach this objective, a combined numerical-experimental approach was proposed to develop a model-based design of an ultrasonic separator. Each individual component of this separator was modelled using a finite element (FE) approach. The numerical simulations were continuously cross-checked with experiments in order to find the best solution possible.

    In this thesis, the source of the acoustic wave is a piezoelectric transducer attached to a glass matching layer of the acoustic cavity, which couples the transducer to the fluid inside the cavity, forming an acoustic resonator/separator. In order to obtain a valid FE transducer model, a limited set of material parameters for the piezoelectric transducer were obtained from the manufacturer, thus preserving prior physical knowledge to a large extent. The remaining unknown parameters were estimated from impedance (admittance) analysis combined with a numerical optimisation routine using 2D and 3D FE models. Thus, a full set of physically interpretable material parameters was obtained. The approach provided adequate accuracy of the estimates of the material parameters, near 1%.

    A similar approach as used for the transducer was applied to an existing ultrasonic separator, again preserving known physical parameters and estimating the remaining unknown or less certain parameters. The results showed that the approach led to a fully calibrated 2D model of the emptyseparator, which was subsequently validated with experiments on a filledseparator chamber. The large sensitivity of the separator to small variations indicated that either such system should be made and operated within tight specifications to obtain the required performance. Alternatively, the operation of the system should be adaptable to cope with a slightly off-spec system, requiring a feedback controller.

    Starting from a fully characterised existing separator with all material parameters found so far, the subsequent step was the actual design of, or extrapolation to, a new separator. A basic design for an industrial scale acoustic separator was obtained based on simulated flow characteristics inside the separation chamber, on acoustic analysis within the chamber and simulated particle trajectories combining these two analyses. Results showed that positioning the piezoelectric transducer surfaces perpendicular to the flow direction and introducing chamber partitioning with multiple flow lanes to enforce laminar flow, resulted in high particle retention. The average particle displacement was found to be related to acoustic pressure in the fluid, showing large retention at peak pressures above 1 MPa or average pressures above 0.5 MPa for small (10 µm), near buoyant (1100 kg/m3) particles at a flow speed of 3.5 cm/s, thus providing comprehensible criteria for subsequent optimisation.

    This basic ultrasonic standing wave separator design was optimised with respect to separation efficiency, throughput and energy consumption. The methodology, using a design of experiments (DOE) approach, showed that it was possible to improve system performance based on acoustic pressure profiles, separation efficiency and flow robustness. Compromising the energy consumption and aiming for maximum separation efficiency with a laminar stable flow up to 5 ml/s resulted in a separator with inner dimensions of 70 mm length, 20 mm width and 28.5 mm height using two transducers perpendicular to the direction of flow and three parallel flow lanes with 9.5 mm height each. The lowest power consumption (with an average of 30 W) with adequate pressure to trap the particles was obtained when it was not operated at the main eigenfrequency.

    Finally, this new ultrasonic particle filter was built and evaluated experimentally. The particle filter was a three channel device, manufactured from glass with four in/outlet ports made of ABS. It was operated in sequenced batch mode and the separation efficiency was determined at three flow rates ranging from 1 to 3 ml/s, using a stock suspension of insoluble potato starch of 1 g/l (1000 ppm). Concentrations of stock, filtrate and concentrate were measured using a turbidity meter and significant effects of acoustic particle concentration were measured at both outlets of the process. The maximum filtration efficiency and concentration efficiency were 54% and 76%, respectively. The performance found was lower than the 100% that was expected for 10 µm particles from the model based design study. The deviation in performance is mainly a result of (i) the pulsation of the feed pump, (ii) differences between the model and the actual prototype, (iii) the limited power supply of only 10 W used and (iv) (too) small particles, below 10 µm, occurring in the starch suspension.

    The best dimensions for an acoustic separator were obtained, but thus far operational characteristics were not yet studied. Operational characterisation and optimisation is the last step in the process of obtaining the best possible solution for operation. With the aim to achieve a high separation efficiency with minimal energy consumption, a model-based open-loop switching control strategy was designed for the commercially available BioSep, using a numerical-experimental approach. Firstly, a dynamic BioSep model structure was derived from mass balances and its system properties were studied. Then, the unknown system parameters were estimated from steady state and dynamic experimental data and subsequently, the switching times of the control input were determined. The model with switching control outputs was then validated by experiments. Finally, the control strategy was implemented in an experimental setup and tested using suspended potato starch. Results showed that the optimal control strategy reached a mass separation efficiency of 96%, which was an improvement of 4% with respect to the initial settings, while using less energy.

    Concluding, a stepwise numerical-experimental approach to acoustic separator design was presented in this study. The minimum power required was estimated to be 22-34 W, resulting in an average electric energy consumption of 1-1.5 kWh/m3. The practical concentration efficiency obtained was 76% at a flow rate of 2 ml/s and a filtration efficiency of 54% at 1 ml/s with a real power input of 8.8 W. An optimal open loop control strategy showed that it is possible to operate an acoustic separator with high separation efficiency using the least power possible. Parallelisation, instead of enlarging the separator, is recommended to scale this system up to larger, industrial flows.

    Calcium phosphate granulation in anaerobic treatment of black water: a new approach to phosphorus recovery
    Tervahauta, T.H. ; Weijden, R.D. van der; Flemming, R.L. ; Hernández, L. ; Zeeman, G. ; Buisman, C.J.N. - \ 2014
    Water Research 48 (2014)1. - ISSN 0043-1354 - p. 632 - 642.
    afvalwaterbehandeling - afvalhergebruik - slibzuivering - calciumfosfaten - fosfor - terugwinning - spectroscopie - infraroodspectroscopie - anaërobe behandeling - biobased economy - waste water treatment - waste utilization - sludge treatment - calcium phosphates - phosphorus - recovery - spectroscopy - infrared spectroscopy - anaerobic treatment - biobased economy - waste-water - precipitation - hydroxyapatite - struvite
    Recovery of phosphorus from wastewater as calcium phosphate could diminish the need for mining of scarce phosphate rock resources. This study introduces a novel approach to phosphorus recovery by precipitation of calcium phosphate granules in anaerobic treatment of black water. The granules formed in the Upflow Anaerobic Sludge Blanket (UASB) reactor at lab- and demonstration-scale were analyzed for chemical composition and mineralogy by Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Electron microprobe (EMP), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and micro X-ray Diffraction (XRD). The granules had a diameter of 1–2 mm, organic content of 33 wt%, and phosphorus content of 11–13 wt%. Three calcium phosphate phases were identified in the granules: hydroxyapatite, calcium phosphate hydrate and carbonated hydroxyapatite. Without any addition of chemicals, 7 gP/person/year can be recovered with the calcium phosphate granules, representing 2% of the incoming phosphorus in the UASB reactor. As the heavy metal content was lower compared to other phosphorus recovery products, phosphate rock and phosphorus fertilizer, the calcium phosphate granules could be considered as a new phosphorus product.
    Handelingsperspectief circulaire economie Amsterdam - Gezamenlijke oplossingen en kansen voor betere kringloopsluiting in Metropoolregio Amsterdam (MRA) - Factsheets bij het visiedocument
    Thoden Van Velzen, E.U. ; Weijma, J. ; Sukkel, W. ; Vader, J. ; Reinhard, A.J. ; Oliemans, W.J. - \ 2013
    LEI (LEI 13-083 13-083) - 83
    afvalverwerking - kringlopen - reststromen - duurzaamheid (sustainability) - stadslandbouw - voedselvoorziening - fosfaat - terugwinning - biobased economy - nieuwe sanitatie - amsterdam - waste treatment - cycling - residual streams - sustainability - urban agriculture - food supply - phosphate - recovery - biobased economy - new sanitation - amsterdam
    Als resultaat van de samenwerking met de Metropoolregio Amsterdam benoemt Wageningen UR in dit document voor vier kringlopen actuele mogelijkheden en bijbehorende maatregelen om de kringlopen zo goed mogelijk te sluiten. In de vorm van factsheets wordt voor elke maatregel uitgewerkt wat deze oplevert voor de dimensies people, planet, profit en proces en wat de kosten, de risico’s en de randvoorwaarden daarbij zijn. De vier kringlopen zijn fosfaat, water, afval en voedsel.
    Terugwinning van fosfaat; Economische verkenning van kansen en mogelijkheden
    Luesink, H.H. ; Broens, D.F. ; Galen, M.A. van; Buisonjé, F.E. de; Georgiev, E.S. - \ 2013
    Den Haag : LEI, onderdeel van Wageningen UR (LEI-rapport : Sector & ondernemerschap ) - ISBN 9789086156481 - 96
    fosfaat - afvalverwerking - kringlopen - terugwinning - mestverwerking - haalbaarheidsstudies - economische haalbaarheid - biobased economy - phosphate - waste treatment - cycling - recovery - manure treatment - feasibility studies - economic viability - biobased economy
    Het Biorenewable Business Platform en Energy Valley hebben LEI Wageningen UR gevraagd een studie uit te voeren voor routes waarlangs fosfaatwinning gestalte kan krijgen. Het onderzoek is gefinancierd door het Inter Provinciaal Overleg (IPO). Namens IPO is de provincie Groningen de opdrachtgever van het onderzoek. In het offertetraject waren in hoofdlijnen de vijf uit te werken routes voor fosfaatterugwinning al vastgelegd. Bij dit onderzoek zijn die vijf routes verder uitgewerkt met daarbij de nadruk op economie en innovativiteit. Belangrijkste uitkomsten: Recycling van fosfaat uit verbrandingsas van zuiveringsslib is praktijkrijp en economisch haalbaar. De economische vooruitzichten voor het recyclen van fosfaat uit varkensmest en organisch industrieel afval zijn heel onzeker. Winning van struviet uit organische afvalstromen is voor fosfaatrecycling economisch niet interessant.
    Prospects of Source-Separation-Based Sanitation Concepts: A Model-Based Study
    Tervahauta, T.H. ; Trang Hoang, ; Hernández, L. ; Zeeman, G. ; Buisman, C.J.N. - \ 2013
    Water 5 (2013)3. - ISSN 2073-4441 - p. 1006 - 1035.
    afvalwaterbehandeling - huishoudens - afvoerwater - nieuwe sanitatie - voedingsstoffen - terugwinning - energieterugwinning - biobased economy - waste water treatment - households - effluents - new sanitation - nutrients - recovery - energy recovery - biobased economy - life-cycle assessment - waste-water treatment - grey water - black water - human urine - constructed wetlands - anaerobic-digestion - domestic sewage - energy
    Separation of different domestic wastewater streams and targeted on-site treatment for resource recovery has been recognized as one of the most promising sanitation concepts to re-establish the balance in carbon, nutrient and water cycles. In this study a model was developed based on literature data to compare energy and water balance, nutrient recovery, chemical use, effluent quality and land area requirement in four different sanitation concepts: (1) centralized; (2) centralized with source-separation of urine; (3) source-separation of black water, kitchen refuse and grey water; and (4) source-separation of urine, feces, kitchen refuse and grey water. The highest primary energy consumption of 914 MJ/capita(cap)/year was attained within the centralized sanitation concept, and the lowest primary energy consumption of 437 MJ/cap/year was attained within source-separation of urine, feces, kitchen refuse and grey water. Grey water bio-flocculation and subsequent grey water sludge co-digestion decreased the primary energy consumption, but was not energetically favorable to couple with grey water effluent reuse. Source-separation of urine improved the energy balance, nutrient recovery and effluent quality, but required larger land area and higher chemical use in the centralized concept.
    Verwerking van mest en zuiveringsslib: kansen voor synergie
    korving, L. ; Verdoes, N. ; Wilt, J. de - \ 2013
    H2O online 2013 (2013)17 mei.
    mestverwerking - waterzuivering - terugwinning - fosfor - stikstof - innovaties - samenwerking - biobased economy - slib - pyrolyse - manure treatment - water treatment - recovery - phosphorus - nitrogen - innovations - cooperation - biobased economy - sludges - pyrolysis
    Bij de verwerking van menselijke en dierlijke mest kunnen meer nutriënten en energie worden teruggewonnen. Waterzuiveraars en mestverwerkers kunnen elkaar versterken door samen in onderzoek en praktijk te werken aan nieuwe verwerkingsmethoden.
    Check title to add to marked list
    << previous | next >>

    Show 20 50 100 records per page

    Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.