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Vandamme D.,Laboratory Aquatic Biology | Foubert I.,Laboratory Aquatic Biology | Fraeye I.,Laboratory Aquatic Biology | Meesschaert B.,Catholic University College of Bruges-Ostend | And 2 more authors.
Bioresource Technology | Year: 2012

Microalgae hold great potential as a feedstock for biofuels or bulk protein or treatment of wastewater or flue gas. Realising these applications will require the development of a cost-efficient harvesting technology. Here, we explore the potential of flocculation induced by high pH for harvesting Chlorella vulgaris. Our results demonstrate that flocculation can be induced by increasing medium pH to 11. Although both calcium and magnesium precipitated when pH was increased, only magnesium (≥0.15. mM) proved to be essential to induce flocculation. The costs of four different bases (sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide and sodium carbonate) were calculated and evaluated and the use of lime appeared to be the most cost-efficient. Flocculation induced by high pH is therefore a potentially useful method to preconcentrate freshwater microalgal biomass during harvesting. © 2011 Elsevier Ltd.


Vandamme D.,Laboratory Aquatic Biology | Foubert I.,Laboratory Aquatic Biology | Meesschaert B.,Catholic University College of Bruges-Ostend | Meesschaert B.,Catholic University of Leuven | Muylaert K.,Laboratory Aquatic Biology
Journal of Applied Phycology | Year: 2010

Due to their small size and low concentration in the culture medium, cost-efficient harvesting of microalgae is a major challenge. We evaluated the potential of cationic starch as a flocculant for harvesting microalgae using jar test experiments. Cationic starch was an efficient flocculant for freshwater (Parachlorella, Scenedesmus) but not for marine microalgae (Phaeodactylum, Nannochloropsis). At high cationic starch doses, dispersion restabilization was observed. The required cationic starch dose to induce flocculation increased linearly with the initial algal biomass concentration. Of the two commercial cationic starch flocculants tested, Greenfloc 120 (used in wastewater treatment) was more efficient than Cargill C*Bond HR 35.849 (used in paper manufacturing). For flocculation of Parachlorella using Greenfloc 120, the cationic starch to algal biomass ratio required to flocculate 80% of algal biomass was 0.1. For Scenedesmus, a lower dose was required (ratio 0.03). Flocculation of Parachlorella using Greenfloc 120 was independent of pH in the pH range of 5 to 10. Measurements of the maximum quantum yield of PSII suggest that Greenfloc 120 cationic starch was not toxic to Parachlorella. Cationic starch may be used as an efficient, nontoxic, cost-effective, and widely available flocculant for harvesting microalgal biomass. © 2009 Springer Science+Business Media B.V.


Van Hulle S.W.H.,Ghent University | Van Hulle S.W.H.,West-Flanders College | Vandeweyer H.J.P.,West-Flanders College | Meesschaert B.D.,Catholic University College of Bruges-Ostend | And 4 more authors.
Chemical Engineering Journal | Year: 2010

The anaerobic ammonium oxidation (Anammox) process, discovered 20 years ago, is, in combination with partial nitritation, ideally suited to treat nitrogen rich waste water streams such as digester effluent. In this review the engineering aspects and the practical application of the process are reviewed. The conventional nitrification-denitrification and nitritation-denitritation are also discussed briefly. The environmental conditions affecting the nitrification process, free ammonia and nitrous acid concentration, temperature, pH and dissolved oxygen concentration, are discussed. These conditions can be controlled in such a way that the partial nitritation step produces an Anammox-suited influent. The Anammox reactor conditions should favour the growth of the Anammox organisms in view of their low growth rate and possible inhibition effects. Dissolved oxygen and nitrite concentrations should be kept as low as possible and biomass washout should be limited. If the partial nitritation process and the Anammox process are occuring in the same reactor, care should be taken to the dissolved oxygen concentration, the ammonium load and the nitrite concentration to obtain a sustainable co-existence between aerobic and anaerobic ammonium oxidizers.An overview is presented of the practical implementation of autotrophic nitrogen removal. The process can be accomplished in the same reactor (1-reactor system) or by using 2 separate reactors (2-reactor system). Typically the 1-reactor system is a biofilm or granular reactor where the ammonium oxidizers are active in the outer layers of the biofilm or granule, producing a suitable amount of nitrite for the Anammox organisms that are active in the inner layers. Transport of ammonium and the produced nitrite is governed by diffusion. Finally, the different nitrogen removal processes are compared in terms of operational conditions and a direction for future work is provided. © 2010 Elsevier B.V.


Strobbe G.,Ghent University | van Mierlo P.,Ghent University | De Vos M.,University of Oldenburg | Mijovic B.,Catholic University of Leuven | And 6 more authors.
NeuroImage | Year: 2014

Several EEG source reconstruction techniques have been proposed to identify the generating neuronal sources of electrical activity measured on the scalp. The solution of these techniques depends directly on the accuracy of the forward model that is inverted. Recently, a parametric empirical Bayesian (PEB) framework for distributed source reconstruction in EEG/MEG was introduced and implemented in the Statistical Parametric Mapping (SPM) software. The framework allows us to compare different forward modeling approaches, using real data, instead of using more traditional simulated data from an assumed true forward model. In the absence of a subject specific MR image, a 3-layered boundary element method (BEM) template head model is currently used including a scalp, skull and brain compartment. In this study, we introduced volumetric template head models based on the finite difference method (FDM). We constructed a FDM head model equivalent to the BEM model and an extended FDM model including CSF. These models were compared within the context of three different types of source priors related to the type of inversion used in the PEB framework: independent and identically distributed (IID) sources, equivalent to classical minimum norm approaches, coherence (COH) priors similar to methods such as LORETA, and multiple sparse priors (MSP). The resulting models were compared based on ERP data of 20 subjects using Bayesian model selection for group studies. The reconstructed activity was also compared with the findings of previous studies using functional magnetic resonance imaging. We found very strong evidence in favor of the extended FDM head model with CSF and assuming MSP. These results suggest that the use of realistic volumetric forward models can improve PEB EEG source reconstruction. © 2014 Elsevier Inc.


Peuteman J.,Catholic University College of Bruges-Ostend | Aeyels D.,Ghent University
Automatica | Year: 2011

An averaging result is presented for local uniform asymptotic stability of nonlinear differential equations without requiring a fast time-varying vectorfield. The nonlinearity plays a crucial role: close to the origin, the trajectories vary slowly compared to the time dependence of the vectorfield. The result generalises averaging results which prove stability properties for systems having a homogeneous vectorfield with positive order. The result is illustrated with several examples. © 2010 Elsevier Ltd. All rights reserved.


Zhang Y.,Catholic University of Leuven | Paepen S.,Catholic University of Leuven | Pinoy L.,Catholic University of Leuven | Pinoy L.,Laboratory for Chemical Process Technology | And 3 more authors.
Separation and Purification Technology | Year: 2012

In view of wastewater recycling and industrial requirements to valorize nutrients and other valuable ions from waste streams, as well as to refine the product streams, a novel electrodialysis stack, denoted as selectrodialysis, was designed and used for ion fractionation. In this work, separation of sulphate from a NaCl/Na 2SO 4 mixture is investigated. Prior to the investigation, the selectrodialysis stack was qualitatively tested on a synthetic wastewater to study the potential of ion fractionation by using this novel configuration. Different approaches including changing of pH and current density were used to evaluate the effects on the stack selectivity, the current efficiency and the product (sulphate) purity. Furthermore, the optimized parameters were applied to produce a sulphate-enriched stream from sulphate-free solutions (NaCl solution) in the product stream. The results show that the sulphate purity can reach over 85% with the current efficiency of over 50%. It is proved that selectrodialysis is feasible and effective for chloride/sulphate fractionation. © 2011 Elsevier B.V. All rights reserved.


Ghyselbrecht K.,Catholic University College of Bruges-Ostend | Huygebaert M.,Deggendorf University of Applied Sciences | Van der Bruggen B.,Catholic University of Leuven | Ballet R.,Nyrstar Belgium NV | And 4 more authors.
Desalination | Year: 2013

The removal of salts from industrial effluents by sustainable techniques is of great interest to many companies. In this study, an industrial saline water, mainly composed of NaCl and KCl, was treated with conventional electrodialysis (ED) and bipolar membrane electrodialysis (EDBM) on lab-scale. The saline water also contained significant amounts of sulfate and calcium, which may give rise to various types of scaling. A partial desalination (target was a removal of 50% of the chlorides) was easily achieved with both ED and EDBM. By using ED, a concentrate containing circa 2M of chlorides was obtained. The formation of scaling was avoided by using monovalent selective anion- and cation-exchange membranes, which was particularly necessary to avoid CaSO4 scaling. A further improvement was obtained by applying EDBM, which yielded an acid and a base stream with a concentration of around 2M, with a relatively good purity. From the initial lab-scale study it was concluded that both ED and EDBM are technologically feasible to desalinate the saline water. In a second phase, the ED scenario was scaled up in a pilot scale study, which demonstrated that the ED pilot plant was operated in a stable way during a long-term experiment. © 2013 Elsevier B.V.


Boehme L.,Catholic University College of Bruges-Ostend
CESB 2013 PRAGUE - Central Europe Towards Sustainable Building 2013: Sustainable Building and Refurbishment for Next Generations | Year: 2013

Aerated concrete is one of the few constituent parts of demolition rubble for which no valid recycling technology has been developed. Anno 2010 aerated concrete is a problem waste fraction. It is undesirable in the stony fraction (concrete rubble, mixed rubble) because of the poorer technical characteristics for the traditional applications in foundations and under foundations of roads. In addition, the chemical composition (leaching of sulphates) may also cause problems in other applications (embankment, supplement, concrete) or in landfills. Recycling the aerated concrete in the production itself (closing the loop) is only possible if the waste product is pure enough, which is after demolition works is not easy to guarantee. There is a need for applications within which this fraction of construction and demolition waste can be recycled, and preferably in as high as possible applications so that a direct or good market can be generated for aerated concrete waste. This paper discusses results from a MIP-project called "Chap-Yt", in which milled recycled aerated concrete was used as an aggregate to partially replace sand in traditional hand-spread sand-cement screed for flooring purposes.


Knockaert J.,West-Flanders College | Pissoort D.,Catholic University College of Bruges-Ostend | Vanhee F.,Catholic University College of Bruges-Ostend
Progress in Electromagnetics Research Symposium | Year: 2011

Electromagnetic interference radiated by a consumer product is measured on a sample of similar devices under test. The EMC-signature of these devices can drift due to aging or deviations in manufacturing. It is proposed to use the Feature Selective Validation method to compare the emission from devices with a reference device in order to have a quality assessment tool.


Claeys K.,Musculoskeletal Research Unit | Claeys K.,Catholic University College of Bruges-Ostend | Brumagne S.,Musculoskeletal Research Unit | Dankaerts W.,Musculoskeletal Research Unit | And 3 more authors.
European Journal of Applied Physiology | Year: 2011

Optimal postural control is an essential capacity in daily life and can be highly variable. The purpose of this study was to investigate if young people have the ability to choose the optimal postural control strategy according to the postural condition and to investigate if non-specific low back pain (NSLBP) influences the variability in proprioceptive postural control strategies. Young individuals with NSLBP (n = 106) and healthy controls (n = 50) were tested on a force plate in different postural conditions (i.e., sitting, stable support standing and unstable support standing). The role of proprioception in postural control was directly examined by means of muscle vibration on triceps surae and lumbar multifidus muscles. Root mean square and mean displacements of the center of pressure were recorded during the different trials. To appraise the proprioceptive postural control strategy, the relative proprioceptive weighting (RPW, ratio of ankle muscles proprioceptive inputs vs. back muscles proprioceptive inputs) was calculated. Postural robustness was significantly less in individuals with NSLBP during the more complex postural conditions (p < 0.05). Significantly higher RPW values were observed in the NSLBP group in all postural conditions (p < 0.05), suggesting less ability to rely on back muscle proprioceptive inputs for postural control. Therefore, healthy controls seem to have the ability to choose a more optimal postural control strategy according to the postural condition. In contrast, young people with NSLBP showed a reduced capacity to switch to a more multi-segmental postural control strategy during complex postural conditions, which leads to decreased postural robustness. © 2010 Springer-Verlag.

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