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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Kostenefficiëntie vergroten door verschuiving van zorg? Laatste nieuws in Nieuwsbrief Alliantie Voeding Gelderse Vallei
Spanjers, K. ; Janse, A. ; Bouwman, L.I. - \ 2014
Alliantie Voeding Gelderse Vallei
Nederland kampt met stijgende kosten in de gezondheidszorg. Om de zorg meer kosteneffectief te maken, stimuleert de overheid transities van interventieprogramma’s van de tweede- en derdelijnszorg naar eerstelijnszorg. Wageningen Universiteit onderzocht recent de voor- en nadelen van de verplaatsing van het behandelprogramma AanTafel! Aan Tafel! AanTafel! is een succesvol behandelprogramma voor kinderen van 3 tot en met 7 jaar met overgewicht. AanTafel! Is ontwikkeld door Ziekenhuis Gelderse Vallei in samenwerking met Wageningen Universiteit. Eind 2013 is het programma ingezet in de eerstelijnszorg in een aantal wijken in Veenendaal. Over het verloop van dergelijke transities is nog weinig bekend.
Convenant "Schoon water Utrechtse fruitteelt"
Spanjers, B. ; Wenneker, M. ; Mombarg, H. ; Bruchem, J. van - \ 2013
H2O online
fruitteelt - pesticiden - waterkwaliteit - emissiereductie - milieubeleid - utrecht - fruit growing - pesticides - water quality - emission reduction - environmental policy
Gewasbeschermingsmiddelen uit de fruitteelt overschrijden op verschillende plekken de norm in grond- en oppervlaktewater van de provincie Utrecht. De belangrijkste boosdoener (captan) en de emissieroutes zijn opgespoord. Fruittelers, waterschap en provincie ontwierpen samen een aanpak voor verbetering.
Synergie RWZI en mestverwerking
Bisschops, I. ; Timmerman, M. ; Weijma, J. ; Eekert, M.H.A. van; Buisonjé, F.E. de; Spanjers, H. - \ 2012
Amersfoort : Stowa (2011-10 ) - 92 p.
Biowaste energy potential in Kenya
Nzila, C. ; DeWulf, J. ; Spanjers, H. ; Kiriamiti, H. ; Langenhove, H. - \ 2010
Renewable Energy 35 (2010)12. - ISSN 0960-1481 - p. 2698 - 2704.
plantenresten - kenya - biogas - methaan - biobased economy - biobrandstoffen - plant residues - methane - biofuels - tea - waste - adsorption - digestion - zinc
Energy affects all aspects of national development. Hence the current global energy crisis demands greater attention to new initiatives on alternative energy sources that are renewable, economically feasible and sustainable. The agriculture-dependent developing countries in Africa can mitigate the energy crisis through innovative use of the available but underutilised biowaste such as organic residues from maize, barley, cotton, tea and sugarcane. Biogas technology is assumed to have the capacity to economically and sustainably convert these vast amounts of biowaste into renewable energy, thereby replacing the unsustainable fossil energy sources, and reducing dependency on fossil fuels. However, the total energy potential of biogas production from crop residues available in Kenya has never been evaluated and quantified. To this end, we selected five different types of residues (maize, barley, cotton, tea and sugarcane) from Kenya and evaluated their energy potential through biomethane potential analysis at 30 °C and a test time of 30 days. The specific methane yields for maize, barley, cotton, tea and sugarcane residues obtained under batch conditions were respectively 363, 271, 365, 67 and 177 m3 per tonne volatile solids. In terms of energy potential, maize, cotton and barley residues were found to be better substrates for methane production than tea and sugarcane residues and could be considered as potential substrates or supplements for methane production without compromising food security in the country. The evaluated residues have a combined national annual maximum potential of about 1313 million cubic meters of methane which represent about 3916 Gigawatt hour (GWh) of electricity and 5887 GWh of thermal energy. The combined electrical potential is equivalent to 73% of the country’s annual power production of 5307 GWh. Utilization of the residues that are readily available on a ‘free on site’ basis for energy production could substitute the fossil fuels that account for a third of the country’s total electricity generation. Besides, exploitation of the potential presented by the biowaste residues can spur an energy revolution in the country resulting in a major economic impact in the region.
Instrumentation in anaerobic treatment - research and practice
Spanjers, H. ; Lier, J.B. van - \ 2006
Water Science and Technology 53 (2006)4-5. - ISSN 0273-1223 - p. 63 - 76.
waste-water treatment - fluidized-bed reactor - monitoring buffer capacity - hydrogen-sulfide sensor - sewage-treatment works - dissolved hydrogen - digestion process - rantox biosensor - control-parameter - online titration
High rate anaerobic treatment reactors are able to uncouple solids and liquid retention time, resulting in high biomass concentrations. Principal advantages of anaerobic treatment include: energy efficiency, low biomass yield, low nutrient requirement and high volumetric organic loadings. In order to facilitate small reactors operation with stable and good performance automatic process control systems in combination with on-line instrumentation are proposed. The paper reviews the development and availability of the principal instrumentation for anaerobic treatment processes. First, the most important measuring principles are discussed, followed by a review of the most important process variables with emphasis on the development of their instrumental measurement techniques and application in research. Finally, a summary of actual application of instrumentation in full-scale anaerobic treatment plants is presented
Automatic detection of exogenous respiration end-point using artificial neural network
Bisschops, I.A.E. ; Spanjers, H. ; Keesman, K.J. - \ 2006
Water Science and Technology 53 (2006)4-5. - ISSN 0273-1223 - p. 273 - 281.
water
When aerobic bacteria receive a biodegradable material such as wastewater, then respiration changes from endogenous to exogenous. The reverse occurs when biodegradation is complete. When using respirometry a respirogram is recorded showing those changes in respiration, and for an expert it is not difficult to point the moments at which they occur. The area corresponding to the exogenous respiration phase is a measure of the easily biodegradable fraction of material, also called the short-term BOD or BODST. That value, in combination with a value for COD, can be used to determine the treatability of wastewater. Respirometry can also be applied on-line, e.g. for on-line monitoring of wastewater. However, automatic detection of the end-point of exogenous respiration is difficult. The first step towards on-line monitoring of wastewater treatability is to make automatic detection of this end-point possible. In this study the use of a neural network for detection of this end-point was investigated. Results are promising; after training the neural network is able to detect the correct end-point in the majority of the studied cases
Waste sizing solution as co-substrate for anaerobic decolourisation of textile dyeing wastewaters
Bisschops, I. ; Santos, A.B. dos; Spanjers, H. - \ 2005
Water Science and Technology 52 (2005)1-2. - ISSN 0273-1223 - p. 397 - 403.
redox mediator - azo-dye - water - effluent - technologies - kinetics - starch
Dyeing wastewaters and residual size are textile factory waste streams that can be treated anaerobically. For successful anaerobic treatment of dyeing effluents, a co-substrate has to be added because of their low concentration of easily biodegradable compounds. Starch-based size contains easily biodegradable material, but is too concentrated to be treated without difficulties. Although residual size makes up only a small volume, when mixed with the other textile wastewater streams it has a considerable impact on the overall organic load. Many textile dyes can pass through a conventional aerobic treatment plant without being degraded. Anaerobic pre-treatment of the dyeing wastewaters before discharge to the aerobic plant can solve this problem, as many dyestuffs are partly degradable under anaerobic conditions, rendering aerobically degradable products. In this study, the possibility of using waste size as a co-substrate for the anaerobic pre-treatment of dyeing wastewaters was investigated. It was found that waste size was applicable as co-substrate for the decolourisation of the two textile dyeing wastewaters studied. Adding a redox mediator could enhance decolourisation rates for both wastewaters
Intrumentation in anaerobic treatment : research and practice
Spanjers, H. ; Lier, J.B. van - \ 2005
In: 2nd IWA Conference on Instrumentation, Control and Automation for Water and Wastewater Treatment and Transport Systems, Korea, 29 May - 2 June 2005. - - p. 105 - 124.
Turbidity-based monitoring of particle concentrations and flocculant requirement in wastewater pre-treatment
Mels, A.R. ; Spanjers, H. ; Klapwijk, A. - \ 2004
Water Science and Technology 50 (2004)11. - ISSN 0273-1223 - p. 173 - 178.
The removal of particulate organic material in the first step of wastewater treatment may result in significant savings of reactor volume and energy at wastewater treatment plants, because the organic loading to pursuing unit operations can be reduced. This article describes experiments into the possibility of using turbidity measurements as a tool to quantify the concentration of particles in raw wastewater and, based on the result, assess the organic polymer requirement. A feed forward polymer dosing strategy based on a fixed polymer to influent-turbidity ratio was developed and tested. The experimental work confirms that turbidity measurements can be used to quantify particulate COD. For the investigated wastewater (both untreated and flocculated samples) a linear relationship was found in a wide range of particulate COD (100¿900 mg O2.l+1) and turbidity (50¿450 NTU). On-line turbidity measurements showed that the particle concentrations in the tested municipal wastewater varied significantly. During dry weather conditions the turbidity fluctuated from 100 to 400 NTU, while in rainy periods fluctuations of 100 to >1,000 NTU were measured. The tested turbidity-related polymer dosing method could be used to create different, constant levels of particle removal, despite large particle concentration variations in the influent. Moreover, it resulted in higher removal efficiencies and a more stable operation compared to the dosing of fixed polymer dose per unit of volume
Modelling anaerobic biomass growth kinetics with a substrate threshold concentration
Ribes, J. ; Keesman, K.J. ; Spanjers, H. - \ 2004
Water Research 38 (2004)20. - ISSN 0043-1354 - p. 4502 - 4510.
geactiveerd slib - afvalwaterbehandeling - biomassa - substraten - kinetica - modellen - activated sludge - waste water treatment - biomass - substrates - kinetics - models - activated-sludge - waste-water - continuous-culture - methanol - batch
Abstract Many bacteria have been observed to stop growing below a certain substrate threshold concentration. In this study, a modification of the Monod kinetics expression has been proposed to take into account this substrate threshold concentration observed in bacterial growth. Besides the threshold concentration no additional parameters have been added to the kinetic expression and so, only the substrate threshold concentration and the half-saturation constant have to be estimated for model calibration purposes. Furthermore, for parameter estimation purposes, practical identifiability of this new function has been studied and the results have been satisfactory. The new model has been applied, as an example, to a simple anaerobic model to simulate the competition for hydrogen between sulphate reducers and methanogens in a thermophilic methanol-fed bioreactor. Oscillatory behaviour and mathematical instabilities have been avoided by using the proposed model. Parameter sensitivities have also been calculated along the simulation period in order to investigate the importance of hydrogen threshold concentration parameters.
Waste sizing solution as co-substrate for anaerobic decolourisation of textile dyeing wastewaters
Bisschops, I.A.E. ; Bezerra Dos Santos, A. ; Spanjers, H. - \ 2004
In: Proceedings of the 10th World Congress on Anaerobic Digestion (AD10-2004), 29 August 2004 - 2 September 2004, Montreal, Canada. - Montreal, Canada : - p. 2313 - 2318.
Benchmarking procedure for full-scale activated sludge plants
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van - \ 2004
Control Engineering Practice 12 (2004)3. - ISSN 0967-0661 - p. 315 - 322.
simulatie - identificatie - controle - afvalwater - oxidatiesloten - prestatie-indexen - prestatieniveau - afvalwaterbehandeling - zuiveren - planten - simulation - identification - control - waste water - oxidation ditches - performance indexes - performance - waste water treatment - purification - plants - oxidation ditch benchmark - waste-water - parameters
To enhance development and acceptance of new control strategies, a standard simulation benchmarking methodology to evaluate the performance of wastewater treatment plants has recently been proposed. The proposed methodology is, however, for a typical plant and that works under typical loading and environmental conditions. Thus, benchmarking a full-scale plant working under different situations is still a problem that needs to be solved. This paper proposes a data based approach to benchmark any specific full-scale activated sludge plant used for carbon and nitrogen removal and using real design, operational and performance data. The advantage of the proposed approach over the "one-typical-plant" approach, is that it takes into account the very specific design and operational characteristics of the plant that will be benchmarked. A real-world illustrative example is also presented in this paper
To enhance development and acceptance of new control strategies, a standard simulation benchmarking methodology to evaluate the performance of wastewater treatment plants has recently been proposed. The proposed methodology is, however, for a typical plant and that works under typical loading and environmental conditions. Thus, benchmarking a full-scale plant working under different situations is still a problem that needs to be solved. This paper proposes a data based approach to benchmark any specific full-scale activated sludge plant used for carbon and nitrogen removal and using real design, operational and performance data. The advantage of the proposed approach over the "one-typical-plant" approach, is that it takes into account the very specific design and operational characteristics of the plant that will be benchmarked. A real-world illustrative example is also presented in this paper. (C) 2003 Elsevier Science Ltd. All rights reserved.
Calibration and validation of a model for competition between methanogens and sulfate-reducersCalibration and validation of a model
Abusam, A. ; Weijma, J. ; Spanjers, H. ; Keesman, K.J. - \ 2002
A procedure for benchmarking specific full-scale activated sludge plants used for carbon and nitrogen removal
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van; Meinema, K. - \ 2002
In: 15th Triennal IFAC World Congress, 2002, Spain, Barcelona. - [S.l.] : [s.n.], 2002. - CD-Rom
To enhance development and acceptance of new control strategies, a standard simulation benchmarking methodology to evaluate the performance of wastewater treatment plants has recently been proposed. The proposed methodology is, however, for a typical plant and typical loading and environmental conditions. Thus, benchmarking a full-scale plant working under different situations is still a problem that needs to be solved. This paper proposes a realistic approach to benchmark specific full-scale activated sludge plants used for carbon and nitrogen removal, based on real design, operational and performance data. An illustrative example is also presented in this paper
Respirometry-based on-line model parameter estimation at a full-scale WWTP
Spanjers, H. ; Patry, G.G. ; Keesman, K.J. - \ 2002
Water Science and Technology 45 (2002). - ISSN 0273-1223 - p. 4 - 5.
afvalwaterbehandeling - geactiveerd slib - respirometrie - meting - modellen - rioolwater - chemisch zuurstofverbruik - waste water treatment - activated sludge - respirometry - measurement - models - sewage - chemical oxygen demand
This paper describes part of a project to develop a systematic approach to knowledge extraction from on-line respirometric measurements in support of wastewater treatment plant control and operation. The paper deals with the following issues: (1) test of the implementation of an automatic set-up consisting of a continuous laboratory respirometer integrated in a mobile trailer with sampling and dosing equipment, and data-acquisition and communication system; (2) assessment of activated sludge/sewage characteristics from sludge respirograms by model parameter estimation; (3) comparison of the parameter estimates with regular plant data and information obtained from supplementary wastewater respirograms. The paper describes the equipment and some of its measuring results from a period of one week at a large-scale wastewater treatment plant. The measurements were evaluated in terms of the common activated sludge modelling practice. The automatic set-up allowed reliable measurements during at least one week. The data were used to calibrate two different version of the model, and independent parameter estimates were obtained.
Estimation of uncertainties in the performance indices of an oxidation ditch benchmark
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van; Meinema, K. - \ 2002
Journal of Chemical Technology and Biotechnology 77 (2002). - ISSN 0268-2575 - p. 1058 - 1067.
afvalwater - afvalwaterbehandeling - geactiveerd slib - oxidatiesloten - modellen - onzekerheid - analyse - prestatieniveau - waste water - waste water treatment - activated sludge - oxidation ditches - models - uncertainty - analysis - performance
Estimation of the influence of different sources of uncertainty is very important in obtaining a thorough evaluation or a fair comparison of the various control strategies proposed for wastewater treatment plants. This paper illustrates, using real data obtained from a full-scale oxidation ditch wastewater treatment plant, how the effect of the various uncertainty sources can be quantified. A Monte Carlo simulation analysis method was preferred over a first-order variance analysis method because it is more reliable and it provides the complete probability distribution. For various sources of uncertainty, except for the additive modelling error, samples were selected using the efficient Latin Hypercube Sampling technique. Large deviations in the benchmark performance indices from the nominal values, due to uncertainty in influent loads and parameter values, were found, in particular, for effluent quality and total sludge production indices. However, relatively smaller deviations are found due to uncertainty in the states' initial conditions. The effect of the model structural uncertainty on the performance indices was found to be negligible. ? 2002 Society of Chemical Industry.
Mesophilic and thermophilic activated sludge post-treatment of paper mill process water
Vogelaar, J.C.T. ; Bouwhuis, E. ; Klapwijk, A. ; Spanjers, H. ; Lier, J.B. van - \ 2002
Water Research 36 (2002). - ISSN 0043-1354 - p. 1869 - 1879.
Increasing system closure in paper mills and higher process water temperatures make the applicability of thermophilic treatment systems increasingly important. The use of activated sludge as a suitable thermophilic post-treatment system for anaerobically pre-treated paper process water from a paper mill using recycled wastepaper was studied. Two lab-scale plug flow activated sludge reactors were run in parallel for 6 months; a thermophilic reactor at 55°C and a reference reactor at 30°C. Both reactors were operated simultaneously at 20, 15 and 10 days SRT. The effects of temperature and SRT on sludge settleability and chemical oxygen demand (COD) removal efficiencies of different fractions were studied. Total COD removal percentages over the whole experimental period were 58±5 t 30°C and 48±10 t 55°C. The effect of the SRT on the total COD removal was negligible. Differences in total COD removal between both systems were due to a lesser removal of soluble and colloidal COD at 55°C compared to the reference system. At 30°C, colloidal COD removal percentages were 65±25°75±17 nd 86±22 t 20, 15 and 10 days SRT, respectively. At 55°C, these percentages were 48±34°40±28 nd 70±25°respectively. The effluent concentrations of colloidal COD in both systems were related to the influent concentration of colloidal material. The thermophilic sludge was not able to retain influent colloidal material as well as the mesophilic sludge causing a higher thermophilic effluent turbidity. Sludge settling properties were excellent in both reactor systems. These were neither temperature nor SRT dependent but were rather caused by extensive calcium precipitation in the aeration tanks creating a very dense sludge. For application in the board industry, a thermophilic in line treatment system seems feasible. The higher effluent turbidity is most likely offset by the energy gains of treatment under thermophilic conditions.
Respirometry techniques and activated sludge models
Benes, O. ; Spanjers, H. ; Holba, M. - \ 2002
Water Science and Technology 46 (2002). - ISSN 0273-1223 - p. 4 - 5.
afvalwaterbehandeling - geactiveerd slib - modellen - respirometrie - acetaten - afvalwater - wiskundige modellen - waste water treatment - activated sludge - models - respirometry - acetates - waste water - mathematical models
This paper aims to explain results of respirometry experiments using Activated Sludge Model No. 1. In cases of insufficient fit of ASM No. 1, further modifications to the model were carried out and the so-called "Enzymatic model" was developed. The best-fit method was used to determine the effect of the proposed modifications. Increased agreement was found between simulated data and respirometry results, particularly for repeated respirometric tests with acetate as the sole substrate. Additionally, the influence of different biomass pre-conditioning methods was examined. Results from repeated respirometric tests suggest that presence of residual products in an activated sludge sample before respiration testing may decrease the sample's activity and significantly affect results from respirometric tests. An innovative approach to recover original activity is suggested by washing activated sludge samples with tap water or "mineral medium". As allylthiourea (ATU) was used in most experiments to suppress endogenous nitrification, its influence on kinetic parameters was reviewed. Respirometric tests confirmed that ATU addition has a significant effect on activity and respiration rate of activated sludge samples and could affect results of respirometric analyses.
Evaluation of control strategies using an oxidation ditch benchmark
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van; Meinema, K. - \ 2002
Water Science and Technology 45 (2002). - ISSN 0273-1223 - p. 4 - 5.
afvalwaterbehandeling - oxidatiesloten - simulatie - controle - evaluatie - prestatieniveau - beoordeling - waste water treatment - oxidation ditches - simulation - control - evaluation - performance - assessment
This paper presents validation and implementation results of a benchmark developed for a specific full-scale oxidation ditch wastewater treatment plant. A benchmark is a standard simulation procedure that can be used as a tool in evaluating various control strategies proposed for wastewater treatment plants. It is based on model and performance criteria development
Effect of oxidation ditch horizontal velocity on the nitrogen removal process
Abusam, A. ; Keesman, K.J. ; Spanjers, H. ; Straten, G. van; Meinema, K. - \ 2002
European water management : official publication of the European Water Pollution Control Association 2002 (2002)06. - ISSN 1461-6971 - p. 1 - 9.
afvalwaterbehandeling - oxidatiesloten - nitraten - prestatieniveau - verwijdering - waste water treatment - nitrates - removal - oxidation ditches - performance
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