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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Re-using bauxite residues : benefits beyond (critical raw) material recovery
Ujaczki, Éva ; Feigl, Viktória ; Molnár, Mónika ; Cusack, Patricia ; Curtin, Teresa ; Courtney, Ronan ; O'Donoghue, Lisa ; Davris, Panagiotis ; Hugi, Christoph ; Evangelou, Michael W.H. ; Balomenos, Efthymios ; Lenz, Markus - \ 2018
Journal of Chemical Technology and Biotechnology 93 (2018)9. - ISSN 0268-2575 - p. 2498 - 2510.
hydrometallurgy - life-cycle assessment (LCA) - metals - recovery - sustainable processing - waste treatment and waste minimization

Since the world economy has been confronted with an increasing risk of supply shortages of critical raw materials (CRMs), there has been a major interest in identifying alternative secondary sources of CRMs. Bauxite residues from alumina production are available at a multi-million tonnes scale worldwide. So far, attempts have been made to find alternative re-use applications for bauxite residues, for instance in cement / pig iron production. However, bauxite residues also constitute an untapped secondary source of CRMs. Depending on their geological origin and processing protocol, bauxite residues can contain considerable amounts of valuable elements. The obvious primary consideration for CRM recovery from such residues is the economic value of the materials contained. However, there are further benefits from re-use of bauxite residues in general, and from CRM recovery in particular. These go beyond monetary values (e.g. reduced investment / operational costs resulting from savings in disposal). For instance, benefits for the environment and health can be achieved by abatement of tailing storage as well as by reduction of emissions from conventional primary mining. Whereas certain tools (e.g. life-cycle analysis) can be used to quantify the latter, other benefits (in particular sustained social and technological development) are harder to quantify. This review evaluates strategies of bauxite residue re-use / recycling and identifies associated benefits beyond elemental recovery. Furthermore, methodologies to translate risks and benefits into quantifiable data are discussed. Ultimately, such quantitative data are a prerequisite for facilitating decision-making regarding bauxite residue re-use / recycling and a stepping stone towards developing a zero-waste alumina production process.

Monitoring vooroeververdediging Oosterschelde en Westerschelde 2014
Tangelder, M. ; Heuvel-Greve, M.J. van den; Kluijver, M. de; Glorius, S.T. ; Jansen, H.M. - \ 2015
Yerseke : IMARES (Rapport / IMARES C102/15) - 141
oeverbescherming van rivieren - dijken - steenwerk - staal - aquatische ecosystemen - biota - metalen - ecotoxicologie - oosterschelde - westerschelde - nederland - riverbank protection - dykes - stonework - steel - aquatic ecosystems - metals - ecotoxicology - eastern scheldt - western scheldt - netherlands
Rijkswaterstaat bestort de vooroevers voor de dijken in de Ooster- en Westerschelde om de waterveiligheid te kunnen blijven waarborgen. Voor deze bestortingen wordt gebruik gemaakt van staalslakken, breukstenen en zeegrind. Om de gevolgen van het bestorten voor het plaatselijke onderwaterleven inzichtelijk te maken wordt monitoring uitgevoerd door IMARES in opdracht van Rijkswaterstaat. Hierbij wordt onderzoek gedaan naar hard substraat soorten (planten en dieren gevestigd op de harde oever), zacht substraat soorten (dieren die in het sediment op de vooroever leven) en mogelijke uitloging van zware metalen vanuit de vooroeverbestorting naar planten en dieren
Gehaltes aan zware metalen in biota op stort- en referentielocaties in de Oosterschelde & Westerschelde : data rapport 2014
Jansen, H.M. ; Glorius, S.T. ; Tangelder, M. ; Heuvel-Greve, M.J. van den - \ 2015
Yerseke : IMARES (Rapport / IMARES C079/15) - 91
oeverbescherming van rivieren - zware metalen - sintels - metalen - verontreiniging - oosterschelde - westerschelde - monitoring - aquatische ecologie - ecotoxicologie - riverbank protection - heavy metals - slags - metals - pollution - eastern scheldt - western scheldt - aquatic ecology - ecotoxicology
Om erosie van de oevers en geulwanden tegen te gaan, is er in 2008 (pilot) en 2009 (structureel) begonnen om ‘bestortingen’ uit te voeren om de oevers te beschermen. Deze bestortingen zijn uitgevoerd met staalslakken (SS) en breukstenen (BS). Om met zekerheid vast te kunnen stellen dat als gevolg van deze bestortingen geen negatieve effecten optreden op het mariene milieu is een monitoringsprogramma ingevoerd om inzicht te krijgen in gehalten aan zware metalen in aanwezige biota meerdere jaren na het aanbrengen van vooroeververdediging. Dit rapport beschrijft de resultaten van de metaalanalyses in biota bemonsterd op verschillende locaties in de Oosterschelde en Westerschelde.
Recycling of Indium From CIGS Photovoltaic Cells: Potential of Combining Acid-Resistant Nanofiltration with Liquid-Liquid Extraction.
Zimmermann, Y.S. ; Niewersch, C. ; Lenz, M. ; Corvini, P.F.X. ; Schäffer, A. ; Wintgens, T. - \ 2014
Environmental Science and Technology 48 (2014)22. - ISSN 0013-936X - p. 13412 - 13418.
electronic waste - nf membranes - recovery - metals - environment - mechanisms - management - rejection - solutes - water
Electronic consumer products such as smartphones, TV, computers, light-emitting diodes, and photovoltaic cells crucially depend on metals and metalloids. So-called “urban mining” considers them as secondary resources since they may contain precious elements at concentrations many times higher than their primary ores. Indium is of foremost interest being widely used, expensive, scarce and prone to supply risk. This study first investigated the capability of different nanofiltration membranes of extracting indium from copper–indium-gallium- selenide photovoltaic cell (CIGS) leachates under low pH conditions and low transmembrane pressure differences (98% by nanofiltration, separating it from parts of the Ag, Sb, Se, and Zn present. LLE using di-(2-ethylhexyl)phosphoric acid (D2EHPA) extracted 97% of the indium from the retentates, separating it from all other elements except for Mo, Al, and Sn. Overall, 95% (2.4 g m–2 CIGS) of the indium could be extracted to the D2EHPA phase. Simultaneously, by nanofiltration the consumption of D2EHPA was reduced by >60% due to the metal concentration in the reduced retentate volume. These results show clearly the potential for efficient scarce metal recovery from secondary resources. Furthermore, since nanofiltration was applicable at very low pH (=0.6), it may be applied in hydrometallurgy typically using acidic conditions.
Geogenic and agricultural controls on the geochemical composition of European agricultural soils
Saaltink, R. ; Griffioen, J. ; Mol, G. ; Birke, M. - \ 2014
Journal of Soils and Sediments 14 (2014)1. - ISSN 1439-0108 - p. 121 - 137.
robust factor-analysis - element concentrations - isotope composition - continental-crust - fertilizers - surface - impact - loess - extraction - metals
Purpose Concern about the environmental impact of agriculture caused by intensification is growing as large amounts of nutrients and contaminants are introduced into the environment. The aim of this paper is to identify the geogenic and agricultural controls on the elemental composition of European, grazing and agricultural soils. Materials and methods Robust factor analysis was applied to data series for Al, B, Ca, Cd, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Se, Sr, U, Zn (ICP-MS) and SiO2, K2O, Na2O, Fe2O3, Al2O3 (XRF) based on the European GEMAS dataset. In addition, the following general soil properties were included: clay content, pH, chemical index of alteration (CIA), loss on ignition (LOI), cation exchange capacity (CEC), total organic carbon (TOC) and total carbon and total sulfur. Furthermore, this dataset was coupled to a dataset containing information of historic P2O5 fertilization across Europe. Also, a mass balance was carried out for Cd, Cu and Zn to determine if concentrations of these elements found in the soils have their origin in historic P2O5 fertilization. Results and discussion Seven geogenic factors and one agricultural factor were found of which four prominent ones (all geogenic): chemical weathering, reactive iron-aluminum oxide minerals, clay minerals and carbonate minerals. Results for grazing and agricultural soils were near identical, which further proofs the prominence of geogenic controls on the elemental composition. When the cumulative amount of P2O5 fertilization was considered, no extra agriculture-related factors became visible. The mass balance confirms these observations.
Leaching of inorganic contaminants towards groundwater : impact assessment of the Dutch Soil Quality Decree on Groundwater
Spijker, J. ; Groenenberg, J.E. ; Comans, R.N.J. ; Dijkstra, J.J. - \ 2013
Bilthoven : RIVM - 201
grondwaterverontreiniging - bodemverontreiniging - uitspoelen - metalen - halfmetalen - verontreinigende stoffen - modelleren - anorganische verbindingen - groundwater pollution - soil pollution - leaching - metals - semimetals - pollutants - modeling - inorganic compounds
Dit rapport beschrijft de opzet, evaluatie en resultaten van een modellering van uitloging van metalen en metalloïden uit bodems naar het grondwater. Deze studie had de volgende doelen: 1. het bepalen van representatieve concentraties van metalen en metalloïden in het ondiepe (eerste meter) grondwater; 2. het bepalen van representatieve waarden voor bodemparameters, die de uitloging van metalen en metalloïden bepalen, zoals reactiviteit van opgelost organische koolstof, gehalten aan oxiden en reactiviteit van metalen en metalloïden; 3. het verbeteren van het bestaande modelinstrumentarium voor het modelleren van de uitloging van metalen en metalloïden uit de bodem, inclusief de onzekerheid van deze modellen.
Simultaneous sulfate reduction and metal precipitation in an inverse fluidized bed reactor
Villa Gomez, D.K. - \ 2013
Wageningen University. Promotor(en): Piet Lens, co-promotor(en): Karel Keesman. - [S.l.] : S.n. - ISBN 9789461737410 - 194
wervelbedden - uitrusting - sulfaatreductie - chemische precipitatie - metalen - fluidized beds - equipment - sulfate reduction - chemical precipitation - metals
The impact of metal transport processes on bioavailability of free and complex metal ions in methanogenic granular sludge
Bartacek, J. ; Fermoso, F.G. ; Vergeldt, F. ; Gerkema, E. ; Maca, J. ; As, H. van; Lens, P.N.L. - \ 2012
Water Science and Technology 65 (2012)10. - ISSN 0273-1223 - p. 1875 - 1881.
afvalwaterbehandeling - bioreactoren - anaërobe omstandigheden - korrelslib - biologische beschikbaarheid - metalen - toxiciteit - kernspintomografie - waste water treatment - bioreactors - anaerobic conditions - granular sludge - bioavailability - metals - toxicity - magnetic resonance imaging - magnetic-resonance - dynamics - immobilization - biofilm - nickel
Bioavailability of metals in anaerobic granular sludge has been extensively studied, because it can have a major effect on metal limitation and metal toxicity to microorganisms present in the sludge. Bioavailability of metals can be manipulated by bonding to complexing molecules such as ethylenediaminetetraacetate (EDTA) or diethylenetriaminepentaacetate (DTPA). It has been shown that although the stimulating effect of the complexed metal species (e.g. [CoEDTA]2-) is very fast, it is not sustainable when applied to metal-limited continuously operated reactors. The present paper describes transport phenomena taking place inside single methanogenic granules when the granules are exposed to various metal species. This was done using magnetic resonance imaging (MRI). The MRI results were subsequently related to technological observations such as changes in methanogenic activity upon cobalt injection into cobalt-limited up-flow anaerobic sludge blanket (UASB) reactors. It was shown that transport of complexed metal species is fast (minutes to tens of minutes) and complexed metal can therefore quickly reach the entire volume of the granule. Free metal species tend to interact with the granular matrix resulting in slower transport (tens of minutes to hours) but higher final metal concentrations.
Soil-plant-animal transfer models to improve soil protection guidelines: A case study from Portugal
Rodrigues, S.M. ; Pereira, M.E. ; Duarte, A.C. ; Römkens, P.F.A.M. - \ 2012
Environment International 39 (2012)1. - ISSN 0160-4120 - p. 27 - 37.
potentially toxic elements - available pools - risk-assessment - food-chain - part ii - cadmium - mercury - lead - metals - sheep
Food chain models are essential tools to assess risks of soil contamination in view of product quality including fodder crops and animal products. Here we link soil to plant transfer (SPT) models for potentially toxic elements (PTEs) including As, Ba, Cd, Co, Cu, Hg, Ni, Pb, Sb, U and Zn with models describing accumulation in animal organs. Current EU standards for food products and acceptable daily intake levels (ADI) for humans were used as critical limits. The combined model is used to assess the impact of soil contamination on animal health, product quality and human health using data from 100 arable fields. Results indicate that 42 existing arable fields near industrial and mining sites are unsuitable for animal grazing in view of food safety due to elevated intake of Cd, Cu, Hg and Pb by cows and sheep. At 10 sites daily intake levels of As by cows exceeded threshold concentrations regarding the quality of animal products. The food chain model also was used inversely to derive soil threshold concentrations in view of EU fodder standards. Calculated threshold levels in soil for As, Cd, Cu, Pb, Hg and Zn appear to be in line with those proposed or used in other EU countries. As such the approach applied here can form a conceptual basis for a more harmonized risk assessment strategy regarding the protection of animal and human health. --------------------------------------------------------------------------------
Evaluation of models for metal partitioning and speciation in soils and their use in risk assessment
Groenenberg, J.E. - \ 2011
Wageningen University. Promotor(en): Rob Comans; Wim de Vries. - [S.l. : S.n. - ISBN 9789085858485 - 218
toxicologie - metalen - bodemchemie - risicoschatting - transportprocessen - geochemie - bodemoplossing - organisch bodemmateriaal - modellen - toxicology - metals - soil chemistry - risk assessment - transport processes - geochemistry - soil solution - soil organic matter - models
In this thesis models were developed and evaluated which describe metal partitioning and speciation in soils. Both partition-relations and multisurface models were developed and evaluated on their performance for a large set of elements
Spatial and seasonal variations of the contamination within water body of the Grand Canal, China
Wang, X.L. ; Han, Jingyi ; Xu, L.G. ; Zhang, Q. - \ 2010
Environmental Pollution 158 (2010)5. - ISSN 0269-7491 - p. 1513 - 1520.
land-use - taihu lake - long-term - chemistry - sediments - pollution - quality - metals - river - hangzhou
To delineate the character of contaminations in the Grand Canal, China, a three-year study (2004-2006) was conducted to investigate variations the water quality in the canal. Results showed that the variation of water quality within the Grand Canal was of there is remarkable spatial and seasonal heterogeneity regarding water quality within the Canal. Values of contaminants in dry-season were obviously higher than those in wet-season. Sites influenced strongly by industry and urbanization showed higher contents of nutrients and lower levels of dissolved oxygen in water body; moreover these sites were severely polluted by dissolved metals with the contents of cadmium, chromium and copper exceeding the Criteria Maximum Concentration (CMC), US EPA. Multivariate statistical analysis suggested nutrient and dissolved metals pollution was the dominant environmental problems within the Canal. Anthropogenic influences played a dominant role in the character of contaminations in the Grand Canal.
Ecological vulnerability in wildlife: Application of a species ranking method to food chains and habitats
Lange, H.J. de; Lahr, J. ; Pol, J.J.C. van der; Faber, J.H. - \ 2010
Environmental Toxicology and Chemistry 29 (2010). - ISSN 0730-7268 - p. 2875 - 2880.
risk-assessment - polluted floodplain - probabilistic model - top predators - river - netherlands - uncertainty - cadmium - metals - owl
Nature development in The Netherlands is often planned on contaminated soils or sediments This contamination may present a risk for wildlife species desired at those nature development sites and must be assessed by specific risk assessment methods In a previous study we developed a method to predict ecological vulnerability in wildlife species by using autecological data and expert judgment in the current study, this method is further extended to assess ecological vulnerability of food chains and terrestrial and aquatic habitat, typical for The Netherlands The method is applied to six chemicals Cd Cu Zn dichlorodiphenyltrichloroethane chlorpyrifos and ivermectin The results indicate that species in different food chains differ in vulnerability with earthworm based food chains the most vulnerable Within and between food chains vulnerability varied with habitat particularly at low trophic levels The concept of habitat vulnerability was applied to a case study of four different habitat types in floodplains contaminated with cadmium and zinc along the river Dommel The Netherlands The alder floodplain forest habitat contained the most vulnerable species The differences among habitat, were significant for Cd We further conclude that the method has good potential for application in mapping of habitat vulnerability Environ Toxicol Chem 2010 29 2875-2880 (C) 2010 SETAC
Effects of animal starvation on the sensitivity of the freshwater amphipod Gammarus pulex to cadmium
Alonso, A. ; Garcia-Johansson, V. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2010
Chemistry and Ecology 26 (2010)3. - ISSN 0275-7540 - p. 233 - 242.
seasonal food limitation - unionized ammonia - stream invertebrates - sublethal responses - pulsed exposure - toxicity - crustacea - survival - metals - tests
Populations of amphipods experience different food availabilities during the year. This may alter their sensitivities to toxicants. However, there is scarce information about the effects of starvation on the tolerance to pollutants, and no data are available for the species Gammarus pulex. Our aim was to evaluate the effects of different levels of starvation on the short-term mortality of G. pulex on exposure to cadmium. Four levels of starvation (0, 3, 5 and 7 days without food) were assessed using two exposure modes: semi-static (4 days exposure to 0.10, 0.20 and 0.35 mg Cd·L-1) and two pulses (2 and 6 h) of 2 mg Cd·L-1. LT50 and peLT50 values (post exposure) were calculated for each concentration and pulse, respectively. Our results show that starvation modifies the sensitivity of G. pulex. In general, at the lowest cadmium concentration (0.10 mg Cd·L-1) less-starved animals in semi-static exposure showed higher sensitivity to cadmium than more-starved animals. This trend was reversed for the highest cadmium exposure. Non-starved animals were more sensitive to cadmium applied in a short pulse than starved animals. Because natural populations are exposed to different food availability, starvation status has to be taken into account to assess the risk of toxicants
Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum
Alonso, A. ; Lange, H.J. de; Peeters, E.T.H.M. - \ 2010
Ecotoxicology 19 (2010)1. - ISSN 0963-9292 - p. 133 - 140.
asellus-aquaticus l - behavioral-responses - unionized ammonia - feeding-activity - toxicity tests - life-stages - crustacea - cadmium - invertebrates - metals
Amphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to: (1) to compare sensitivities to ivermectin and cadmium between two species of freshwater amphipods (G. pulex and G. fossarum); (2) to compare sensitivities to these toxicants between juveniles and adults within each species; and (3) to assess whether the sensitivity to toxicants of these co-generic species is related with the wideness of their natural distribution area. Eight independent short-term bioassays (96 h) were conducted to assess sensitivity for ivermectin and cadmium for juvenile and adult life stages for each species. The LC50 (mortality) and EC50 (mortality plus immobility) were calculated to 48 and 96 h of continuous exposure. Our results showed that G. pulex was less tolerant to ivermectin than G. fossarum, the reverse being true for cadmium. In general, juveniles of both species were less tolerant to cadmium than adults. In the case of ivermectin, only for G. fossarum EC50 values were different between life stages. These results suggest that the risk assessment of toxicants to freshwater amphipods should include bioassays with the most sensitive species and life stage
Upgrading system-oriented ecotoxicological research
Eijsackers, H.J.P. ; Groot, M. ; Breure, A.M. - \ 2008
Science of the Total Environment 406 (2008)3. - ISSN 0048-9697 - p. 373 - 384.
sediment quality triad - river rhine - soil - netherlands - populations - floodplains - ecosystems - pollution - recovery - metals
In the 1990s the Dutch government expressed the need to investigate the impacts of diffuse pollution at (sub)-ecosystem levels. The resulting Netherlands Stimulation Programme on System-oriented Ecotoxicological Research (SSEO programme) ran from 1998 to 2006. Its primary objective was to assess the impacts of low- to medium-level, diffuse, multiple contaminations on ecosystems. The research results were intended as underpinning for policies on environmental, conservation and nature issues. Research was carried out at three sites that were selected because of their importance for nature management and the presence of diffuse contamination. These sites were: a river meadow/floodplain area (Afferdensche en Deestsche Waarden), an estuarine reed-land area (Biesbosch) and an area of lowland peat soils that had been contaminated with urban waste in past centuries (De Ronde Venen).
A Chain Modeling Approach To Estimate the Impact of Soil Cadmium Pollution on Human Dietary Exposure
Franz, E. ; Romkens, P.F.A.M. ; Raamsdonk, L.W.D. van; Fels-Klerx, H.J. van der - \ 2008
Journal of Food Protection 71 (2008)12. - ISSN 0362-028X - p. 2504 - 2513.
dairy-cattle - lead - tissues - ingestion - children - germany - mercury - metals - food - netherlands
Cadmium in soil poses a risk for human health, due to its accumulation in food and feed crops. The extent of accumulation depends strongly on soil type and the degree of pollution. The objective of the present study was to develop a predictive model to estimate human dietary cadmium exposure from soil characteristics. This chain model consists of three basic steps: (i) calculation of plant cadmium levels from soil contamination levels and soil characteristics, (ii) calculation of animal transfer from consumption and contamination levels, and (iii) human exposure from both plant and animal products. Six soil scenarios were assessed, reflecting a specific contaminated region and ranging from 0.5 mg/kg of Cd (pH 4.5) to 2.5 mg/kg of Cd (pH 5.5). Cadmium levels in feed crops and vegetables were estimated with regression and mathematical models. Animal exposure and transfer to cattle kidneys, livers, and meat were calculated using a consumption database and a parameterized linear simulation model. Human exposure was estimated by Monte Carlo simulation, using a consumption database. The median human exposure for the different scenarios ranged from 0.24 to 0.98 ¿g/kg of body weight per day, which is comparable to results obtained from exposure levels based on observed field contamination data. The study shows that a chain model approach from soil contamination to human exposure, including animal exposure and transfer to animal products, can successfully be applied. The model can be used for fast evaluation of dietary cadmium exposure and the identification of risk areas based on soil conditions.
Nematode-based risk assessment of mixture toxicity in a moderately polluted river floodplain in The Netherlands
Vliet, P.C.J. van; Goede, R.G.M. de - \ 2008
Science of the Total Environment 406 (2008)3. - ISSN 0048-9697 - p. 449 - 454.
stroomvlakten - zware metalen - nematoda - rivieren - indicatoren - graslanden - verontreiniging - toxiciteit - gelderland - land van maas en waal - waal - floodplains - heavy metals - rivers - indicators - grasslands - pollution - toxicity - river waal - soil - sensitivity - communities - cadmium - metals - forest
Heavy metal polluted soils usually contain mixtures of different metals, whereas legislation is derived from concentrations of individual metals. The mixture toxicity of the Dutch floodplain Afferdensche and Deestsche Waarden was estimated to be high (msPAF ranged from 67¿94%). Analyses of nematode community based bioindicators (Maturity Index, taxonomic diversity, trophic groups, multivariate analysis, DoFT-sentinels) were used to determine the ecological effects of the mixture toxicity in the floodplain soil. None of the indices indicated direct effects of heavy metals on the nematode community. This can be explained by the high adsorption of heavy metals on organic matter and clay particles resulting in a low bioavailability, and questions the estimation of the toxicity based on total concentrations of heavy metals in such environments. The nematode fauna showed great seasonal variation, which most probably was related to the temporal inundation of the floodplain.
Modelling and on-line estimation of zinc sulphide precipitation in
Grootscholten, T.I.M. ; Keesman, K.J. ; Lens, P.N.L. - \ 2008
Separation and Purification Technology 63 (2008)3. - ISSN 1383-5866 - p. 654 - 660.
parametric sensitivity control - zns precipitation - metals - recovery - state
In this paper the ZnS precipitation in a continuously stirred tank reactor (CSTR) is modelled using mass balances. The dynamics analysis of the model reveals that the ZnS precipitation shows a two time-scales behaviour with inherent numerical stability problems, which therefore needs special attention during implementation. The mass balance model allows the design of an on-line estimator of the zinc concentration and precipitation rate, given only wet-chemical measurements of the sulphide concentration and of the pH in the reactor. The on-line estimation algorithm, also called observer or software sensor, is tested in a simulation experiment with a block disturbance showing numerically stable results. Furthermore, on the basis of real-world experimental data, the observer shows an appropriate performance. The estimation procedure offers good possibilities to be applied for other metal removal processes.
On-line estimation of the dissolved zinc concentration during ZnS precipitation in a continuous stirred tank reactor (CSTR)
Grootscholten, T.I.M. ; Keesman, K.J. ; Lens, P.N.L. - \ 2008
Water Science and Technology 57 (2008)10. - ISSN 0273-1223 - p. 1627 - 1633.
oppervlaktewater - afvalwaterbehandeling - zware metalen - zink - chemische precipitatie - verwijdering - sulfiden - selectiviteit - waterzuivering - surface water - waste water treatment - heavy metals - zinc - chemical precipitation - removal - sulfides - selectivity - water treatment - metals
In this paper a method is presented to estimate the reaction term of zinc sulphide precipitation and the zinc concentration in a CSTR, using the read-out signal of a sulphide selective electrode. The reaction between zinc and sulphide is described by a non-linear model and therefore classical observer theory cannot be applied directly, as this theory was initially developed for linear systems. However, by linear reparametrization of this non-linear system, the linear observer theory can be applied in an effective way. This is illustrated by a zinc sulphide example using real data.
Metal supplementation to anaerobic granular sludge bed reactors: an environmental engineering approach
Gonzalez Fermoso, F. - \ 2008
Wageningen University. Promotor(en): Jules van Lier; Piet Lens. - S.l. : S.n. - ISBN 9789085048787 - 247
rioolslib - anaërobe omstandigheden - bioreactoren - metalen - supplementen - sewage sludge - anaerobic conditions - bioreactors - metals - supplements
The objective of this research is the optimization of essential metal dosing in upflow anaerobic sludge bed (UASB) reactors used for methanogenic wastewater treatment. Optimization of essential metal dosing in UASB reactors is a compromise between achieving the maximal biological activity of the biomass present in the reactor, while minimizing the costs of the supplied metal and the metal losses into the environment. The fate of metals in the anaerobic granular sludge is studied. The boundary conditions to keep a stable reactor operation are evaluated: Nutrient deficiency due to lack of essential metals versus toxicity in case of their excess. Finally, metal dosing strategies are evaluated. It is shown that the metal addition to UASB reactors and the methanogenic activity are related and, more important, this relation can be quantified
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