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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    Granule-based immobilization and activity enhancement of anammox biomass via PVA/CS and PVA/CS/Fe gel beads
    Wang, Jinxing ; Liang, Jidong ; Sun, Li ; Li, Gaigai ; Temmink, Hardy ; Rijnaarts, Huub H.M. - \ 2020
    Bioresource Technology 309 (2020). - ISSN 0960-8524
    Aggregation - Anammox - Gel beads - Immobilization

    Granule-based immobilization of anammox biomass assisted by polyvinyl alcohol/chitosan (PVA/CS) and PVA/CS/Fe gel beads was studied, via the operation of three identical up-flow reactors (R1 without gel beads, R2 with PVA/CS, R3 with PVA/CS/Fe) for 203 days. In the end, the nitrogen removal rates (NRR) were 5.3 ± 0.4, 10.0 ± 0.3 and 13.9 ± 0.5 kg-N m−3 d−1 for R1, R2 and R3, respectively. The porous PVA/CS and PVA/CS/Fe created a suitable eco-niche for anammox bacteria to grow and attach, thus being retained in the reactor. The EPS entangles newly grown cells within the gel beads, resulting in compact aggregation. The interaction between Fe ions added to PVA/CS/Fe gel beads and negatively charged EPS groups strongly promoted granule strength and compactness. The immobilization method proposed by this study was found to effectively improve biomass retention in the reactors, which is promising for advanced anammox process applications.

    Boric Acid Cross-linked 3D Polyvinyl Alcohol Gel Beads by NaOH-Titration Method as a Suitable Biomass Immobilization Matrix
    Sun, Li ; Wang, Jinxing ; Liang, Jidong ; Li, Gaigai - \ 2020
    Journal of Polymers and the Environment 28 (2020). - ISSN 1566-2543 - p. 532 - 541.
    Boric acid - Cross-linking - Gel beads - Immobilization - Polyvinyl alcohol

    Granule-base immobilization of biomass is a potential method for a decent quality granular sludge cultivation. In this study, 3D polyvinyl alcohol (PVA) gel beads were chemically cross-linked via a simple NaOH-titration method. The PVA gel beads’ porous morphology was characterized using scanning electron microscope (SEM) and Brunauer–Emmette–Teller (BET), and their mechanical properties were evaluated by swelling rate and compressive stress tests. When cross-linking time was 10 min, high quality gel beads (P10) were synthesized, which demonstrated a homogeneous porous structure, good swelling rate, and high compressive strength. A mechanism for synthesis of the gel beads was proposed based on the results of Fourier transform infrared (FTIR) and X-ray diffractometer (XRD) analysis. Briefly, the intermolecular hydrogen bonds of PVA were firstly broken by NaOH to generate active bond of O–Na, which easily reacted with B(OH)4 to produce the PVA-boric acid gel beads. P10 showed excellent biocompatibility for anaerobic ammonia oxidation (anammox) biomass’ immobilization. After incubation for three months, well granule-base immobilized sludge on P10 was developed in up-flow reactor. The sludge had high abundance of anammox biomass and was in balance with other functional bacteria. This work provides a simple method for the rapid preparation of 3D PVA gel beads and verifies their potential in granule-base immobilization of biomass.

    Use of iron oxide nanoparticles for immobilizing phosphorus in-situ : Increase in soil reactive surface area and effect on soluble phosphorus
    Koopmans, G.F. ; Hiemstra, T. ; Vaseur, C. ; Chardon, W.J. ; Voegelin, A. ; Groenenberg, J.E. - \ 2020
    Science of the Total Environment 711 (2020). - ISSN 0048-9697
    Immobilization - Iron oxide sludge - Particle size - Phosphate - Siliceous ferrihydrite - Specific surface area

    Phosphorus (P) immobilization has potential for reducing diffuse P losses from legacy P soils to surface waters and for regenerating low-nutrient ecosystems with a high plant species richness. Here, P immobilization with iron oxide sludge application was investigated in a field trial on a noncalcareous sandy soil. The sludge applied is a water treatment residual produced from raw groundwater by Fe(II) oxidation. Siliceous ferrihydrite (Fh) is the major Fe oxide type in the sludge. The reactive surface area assessed with an adapted probe ion method is 211–304 m2 g−1 for the Fe oxides in the sludge, equivalent to a spherical particle diameter of ~6–8 nm. This size is much larger than the primary Fh particle size (~2 nm) observed with transmission electron microscopy. This can be attributed to aggregation initiated by silicate adsorption. The surface area of the indigenous metal oxide particles in the field trial soils is much higher (~1100 m2 g−1), pointing to the presence of ultra-small oxide particles (2.3 ± 0.4 nm). The initial soil surface area was 5.4 m2 g−1 and increased linearly with sludge application up to a maximum of 12.9 m2 g−1 when 27 g Fe oxides per kg soil was added. In case of a lower addition (~10–15 g Fe oxides per kg soil), a 10-fold reduction in the phosphate (P-PO4) concentration in 0.01 M CaCl2 soil extracts to 0.3 µM was possible. The adapted probe ion method is a valuable tool for quantifying changes in the soil surface area when amending soil with Fe oxide-containing materials. This information is important for mechanistically predicting the reduction in the P-PO4 solubility when such materials are used for immobilizing P in legacy P soils with a low P-PO4 adsorption capacity but with a high surface loading.

    Utilization of a Novel Chitosan/Clay/Biochar Nanobiocomposite for Immobilization of Heavy Metals in Acid Soil Environment
    Arabyarmohammadi, Hoda ; Darban, Ahmad Khodadadi ; Abdollahy, Mahmoud ; Yong, Raymond ; Ayati, Bita ; Zirakjou, Abbas ; Zee, Sjoerd E.A.T.M. van der - \ 2018
    Journal of Polymers and the Environment 26 (2018)5. - ISSN 1566-2543 - p. 2107 - 2119.
    Biochar - Heavy metals - Immobilization - Nanobiocomposite - Soil - SPLP
    An organic–inorganic composite of chitosan, nanoclay, and biochar (named as MTCB) was chosen to develop a bionanocomposite to simultaneously immobilize Cu, Pb, and Zn metal ions within the contaminated soil and water environments. The composite material was structurally and chemically characterized with the XRD, TEM, SEM, BET, and FT-IR techniques. XRD and TEM results revealed that a mixed exfoliated/intercalated morphology was formed upon addition of small amounts of nanoclay (5% by weight). Batch adsorption experiments showed that the adsorption capacity of MTCB for Cu2+, Pb2+, and Zn2+ were much higher than that of the pristine biochar sample (121.5, 336, and 134.6 mg g−1 for Cu2+, Pb2+, and Zn2+, respectively). The adsorption isotherm for Cu2+ and Zn2+ fitted satisfactorily to a Freundlich model while the isotherm of Pb2+ was best represented by a Temkin model. That the adsorption capacity increased with increasing temperature is indicative of the endothermic nature of the adsorption process. According to the FTIR analysis, the main mechanism involved in immobilization of metals is binding with –NH2 groups. Results from this study indicated that modification of biochar by chitosan/clay nanocomposite enhances its potential capacity for immobilization of heavy metals, rendering the bionanocomposite into an efficient heavy metal sorbent in mine-impacted acidic waters and soils.
    Plant biomass, soil microbial community structure and nitrogen cycling under different organic amendment regimes; a 15N tracer-based approach
    Heijboer, Amber ; Berge, Hein F.M. ten; Ruiter, Peter C. de; Jørgensen, Helene Bracht ; Kowalchuk, George A. ; Bloem, Jaap - \ 2016
    Applied Soil Ecology 107 (2016). - ISSN 0929-1393 - p. 251 - 260.
    Immobilization - Mineral fertilizer - Mineralization - Organic amendments - Phospholipid fatty acids - Soil microbial community

    Sustainable agriculture requires nutrient management options that lead to a profitable crop yield with relatively low nitrogen (N) losses to the environment. We studied whether the addition of contrasting organic amendments together with inorganic fertilizer can promote both requirements simultaneously. In particular we studied how the chemical composition of organic amendments affects the biomass, activity and composition of the soil microbial community and subsequently carbon (C) and N mineralization, microbial N immobilization and plant growth and nutrient uptake. In a pot experiment, Brussels sprouts (Brassica oleracea, cvar. Cyrus) were grown on arable soil, mixed with 15N-labelled mineral fertilizer and different kinds of organic amendments (cattle manure solid fraction, maize silage, lucerne silage, wheat straw) differing in C:N ratio and lignin content. After 69 and 132 days, destructive sampling took place to assess the effects of the different treatments on soil microbial biomass (microscopic measurements), microbial community composition (phospholipid fatty acid profiles), soil microbial activity (14C-leucine incorporation), C and N mineralization, plant biomass and 15N retrieval in soil pools, microbial biomass and plant biomass. Addition of organic amendments increased soil microbial biomass, activity and fungal/bacterial ratio and created distinct microbial community compositions, whereby high C:N ratio organic amendments had stronger effects compared to low C:N ratio amendments. Structural equation modelling showed that higher values of soil microbial activity were associated with increased N mineralization rates, increased plant biomass and plant 15N uptake, while microbial 15N immobilization was associated with soil microbial community composition. The outcomes of this study highlight the importance of the chemical composition and the amount of the organic amendments for finding a balance between plant N uptake, microbial N immobilization and N retention in labile and stable soil pools through the effects on the composition and activity of the soil microbial community. The results provide insights that can be used in designing combined input (nutrient and organic) nutrient management strategies for a more sustainable agriculture.

    Differences in activity and N demand between bacteria and fungi in a microcosm incubation experiment with selective inhibition
    Kooijman, A.M. ; Bloem, J. ; Dalen, B.R. van; Kalbitz, K. - \ 2016
    Applied Soil Ecology 99 (2016). - ISSN 0929-1393 - p. 29 - 39.
    Cycloheximide - Immobilization - Lime-poor - Lime-rich - Net N-mineralization - Streptomycin

    Bacteria and fungi are important micro-organisms in the soil, but may differ in their impact on net N-mineralization. The hypothesis was tested that fungi are characterized by low microbial activity, but also low immobilization, and bacteria by high activity and high immobilization. A one-month laboratory incubation experiment with selective inhibition of fungi (cycloheximide) or bacteria (streptomycin) was conducted with samples of organic layer and mineral topsoil (0-10. cm) from neutral, bacteria-dominated and acidic, fungi-dominated Luxembourg beech forests. In the control treatment, respiration was higher in neutral than in acidic soil, but net N-mineralization was lower, due to higher immobilization. In the antibiotic treatments, differences in nitrification suggest that selective inhibition indeed occurred; in all soils and horizons, nitrification was especially limited by bactericide. Besides as inhibitor of the target group, antibiotics may also serve as source of C and N for the non-target group. For both bactericide and fungicide, acidic soils showed higher net recovery of C and N from antibiotics than neutral soil, which suggests that uptake or sorption of antibiotics is higher in the latter. Clear differences between neutral and acidic soils arose when the main micro-organisms were stimulated. In bacteria-dominated neutral soil, application of fungicide led to increased microbial respiration. In fungi-dominated acidic soil, however, application of bactericide did not lead to higher respiration, but to increased net N-mineralization per unit respiration, which supports a lower immobilization. Differences between antibiotics were consistent for organic layer and mineral topsoil, with increase in activity with fungicide, and lower immobilization with bactericide. The results provide correlative and experimental evidence that reduced immobilization by fungi compensates for their lower rates of activity with respect to N-availability to the vegetation.

    Increase of stability of oleate hydratase by appropriate immobilization technique and conditions
    Todea, Anamaria ; Hiseni, Aida ; Otten, Linda G. ; Arends, Isabel W.C.E. ; Peter, Francisc ; Boeriu, C.G. - \ 2015
    Journal of Molecular Catalysis. B, Enzymatic 119 (2015). - ISSN 1381-1177 - p. 40 - 47.
    10-Hydroxystearic acid - Chitosan - Immobilization - Magnetic particles - Oleate hydratase

    The enzymatic hydration of oleic acid, one of the most abundant natural unsaturated fatty acids, into 10-hydroxystearic acid (10HSA) represents a subject of considerable scientific and practical interest. Commercial application of the process requires, however, the stabilization and reuse of the biocatalyst. Recombinant oleate hydratase (OHase) from Elizabethkingia meningoseptica expressed in Escherichia coli was purified and immobilized for the first time by different immobilization strategies. Among the tested immobilization methods, immobilization yields higher than 90% and recovered activities up to 30% were achieved by covalent binding onto chitosan magnetic composites. The resulting biocatalysts have been characterized in detail in terms of stability and reusability. The thermal stability was enhanced after immobilization. The immobilized OHase preserved 40% of the initial activity at 50 °C, while the native enzyme was completely inactivated. Immobilization resulted in a radical improvement of operational stability of OHase, as the covalently bound enzyme preserved 75% of the initial activity after five reuses.

    Nitrate consumption alterations induced by alginate-entrapment of Chlamydomonas reinhardtii cells
    Garbayo, Inés ; Vigara, A.J. ; Conchon, Valerie ; Martins Dos Santos, Vitor A.P. ; Vílchez, Carlos - \ 2000
    Process Biochemistry 36 (2000)5. - ISSN 1359-5113 - p. 459 - 466.
    Bioremoval - Chlamydomonas - Immobilization - Microalgae - Nitrate consumption - Photosynthetic activity

    Nitrate consumption of Chlamydomonas reinhardtii cells immobilized in calcium alginate beads was characterized and compared with nitrate consumption of freely suspended cells. In immobilized C. reinhardtii cells an apparent K(s) for nitrate of 0.21 mM was calculated. The entrapped cells showed no nitrate consumption at concentrations lower than 0.14 mM whereas the suspended cells almost fully consumed it. Immobilized cells maintained high rates of nitrate uptake and viability (light-dependent oxygen measurements, LDOP) in a wider range of pH (5.5-8.0) and temperature (25-38.C) than the freely suspended cells, revealing a protective effect of the polymer on the biological activity. In immobilized C. reinhardtii cells a possible inhibition of nitrate consumption by nitrite was observed. Although in freely suspended cell cultures nitrate and nitrite were consumed simultaneously, in immobilized cells nitrate consumption proceeded last, and this could be of practical interest. To test the potential of immobilized C. reinhardtii cells in nitrate consumption processes, a discontinuous flow process was performed under the previously determined nitrate-uptake conditions. The average uptake rate over the studied period was 50 μmol NO3- per mg Chl per day, with a constant biomass concentration (cell load) of 130-140 μg Chl per g. The immobilized cells remained operative for at least 35 days. (C) 2000 Published by Elsevier Science Ltd.

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