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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    Mimicry of emergent traits amplifies coastal restoration success
    Temmink, Ralph J.M. ; Christianen, Marjolijn J.A. ; Fivash, Gregory S. ; Angelini, Christine ; Boström, Christoffer ; Didderen, Karin ; Engel, Sabine M. ; Esteban, Nicole ; Gaeckle, Jeffrey L. ; Gagnon, Karine ; Govers, Laura L. ; Infantes, Eduardo ; Katwijk, Marieke M. van; Kipson, Silvija ; Lamers, Leon P.M. ; Lengkeek, Wouter ; Silliman, Brian R. ; Tussenbroek, Brigitta I. van; Unsworth, Richard K.F. ; Yaakub, Siti Maryam ; Bouma, Tjeerd J. ; Heide, Tjisse van der - \ 2020
    Nature Communications 11 (2020)1. - ISSN 2041-1723

    Restoration is becoming a vital tool to counteract coastal ecosystem degradation. Modifying transplant designs of habitat-forming organisms from dispersed to clumped can amplify coastal restoration yields as it generates self-facilitation from emergent traits, i.e. traits not expressed by individuals or small clones, but that emerge in clumped individuals or large clones. Here, we advance restoration science by mimicking key emergent traits that locally suppress physical stress using biodegradable establishment structures. Experiments across (sub)tropical and temperate seagrass and salt marsh systems demonstrate greatly enhanced yields when individuals are transplanted within structures mimicking emergent traits that suppress waves or sediment mobility. Specifically, belowground mimics of dense root mats most facilitate seagrasses via sediment stabilization, while mimics of aboveground plant structures most facilitate marsh grasses by reducing stem movement. Mimicking key emergent traits may allow upscaling of restoration in many ecosystems that depend on self-facilitation for persistence, by constraining biological material requirements and implementation costs.

    Endogenous regime change : Lessons from transition pathways in Dutch dairy farming
    Runhaar, Hens ; Fünfschilling, Lea ; Pol-Van Dasselaar, Agnes van den; Moors, Ellen H.M. ; Temmink, Rani ; Hekkert, Marko - \ 2020
    Environmental Innovation and Societal Transitions 36 (2020). - ISSN 2210-4224 - p. 137 - 150.
    Governance - Grazing - Institutional logics - Productivist agriculture - The Netherlands - Transformation

    Sustainability transitions are commonly considered impossible without regime change. Theoretical work on regime change has mainly focused on niches and landscapes and less on change ‘from within’. Empirical analysis helps theorising endogenous regime change. Conceptualising regimes as semi-coherent entities composed of multiple ‘institutional logics’, we analyse the endogenous regime change in Dutch dairy farming. Practices in this sector have become more and more market-driven. This dominant logic however was increasingly challenged by institutional logics centring round cultural identity and sustainability. Tensions particularly centred round the increased indoor housing of cows. The contestation of this practice eventually led to a first ‘crack’ in the regime, as it weakened the dominance of the market logic and enabled opportunities for more sustainability. Our case study shows that the presence of alternative institutional logics is necessary to crack the regime, but opportunities to patch it back together are similarly crucial to enable sustainability transitions.

    Cation exchange membrane behaviour of extracellular polymeric substances (EPS) in salt adapted granular sludge
    Sudmalis, D. ; Mubita, T.M. ; Gagliano, M.C. ; Dinis, E. ; Zeeman, G. ; Rijnaarts, H.H.M. ; Temmink, H. - \ 2020
    Water Research 178 (2020). - ISSN 0043-1354
    Anaerobic granular sludge - EPS - Ion selectivity - Ion transport - Methanogenic activity

    This paper aims to elucidate the role of extracellular polymeric substances (EPS) in regulating anion and cation concentrations and toxicity towards microorganisms in anaerobic granular sludges adapted to low (0.22 M of Na+) and high salinity (0.87 M of Na+). The ion exchange properties of EPS were studied with a novel approach, where EPS were entangled with an inert binder (PVDF-HFP) to form a membrane and characterized in an electrodialysis cell. With a mixture of NaCl and KCl salts the EPS membrane was shown to act as a cation exchange membrane (CEM) with a current efficiency of ∼80%, meaning that EPS do not behave as ideal CEM. Surprisingly, the membrane had selectivity for transport of K+ compared to Na+ with a separation factor (SK+/Na+) of 1.3. These properties were compared to a layer prepared from a model compound of EPS (alginate) and a commercial CEM. The alginate layer had a similar current efficiency (∼80%.), but even higher SK+/Na+ of 1.9, while the commercial CEM did not show selectivity towards K+ or Na+, but exhibited the highest current efficiency of 92%. The selectivity of EPS and alginate towards K+ transport has interesting potential applications for ion separation from water streams and should be further investigated. The anion repelling and cation binding properties of EPS in hydrated and dehydrated granules were further confirmed with microscopy (SEM-EDX, epifluorescence) and ion chromatography (ICP-OES, IC) techniques. Results of specific methanogenic activity (SMA) tests conducted with 0.22 and 0.87 M Na+ adapted granular sludges and with various monovalent salts suggested that ions which are preferentially transported by EPS are also more toxic towards methanogenic cells.

    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.

    Microbial Community Drivers in Anaerobic Granulation at High Salinity
    Gagliano, Maria Cristina ; Sudmalis, Dainis ; Pei, Ruizhe ; Temmink, Hardy ; Plugge, Caroline M. - \ 2020
    Frontiers in Microbiology 11 (2020). - ISSN 1664-302X
    16S rRNA gene sequencing - Defluviitaleaceae - EPS - filamentous microorganisms - fluorescence in situ hybridization - granular sludge - Methanosaeta - UASB

    In the recent years anaerobic sludge granulation at elevated salinities in upflow anaerobic sludge blanket (UASB) reactors has been investigated in few engineering based studies, never addressing the microbial community structural role in driving aggregation and keeping granules stability. In this study, the combination of different techniques was applied in order to follow the microbial community members and their structural dynamics in granules formed at low (5 g/L Na+) and high (20 g/L Na+) salinity conditions. Experiments were carried out in four UASB reactors fed with synthetic wastewater, using two experimental set-ups. By applying 16S rRNA gene analysis, the comparison of granules grown at low and high salinity showed that acetotrophic Methanosaeta harundinacea was the dominant methanogen at both salinities, while the dominant bacteria changed. At 5 g/L Na+, cocci chains of Streptoccoccus were developing, while at 20 g/L Na+ members of the family Defluviitaleaceae formed long filaments. By means of Fluorescence in Situ Hybridization (FISH) and Scanning Electron Microscopy (SEM), it was shown that aggregation of Methanosaeta in compact clusters and the formation of filaments of Streptoccoccus and Defluviitaleaceae during the digestion time were the main drivers for the granulation at low and high salinity. Interestingly, when the complex protein substrate (tryptone) in the synthetic wastewater was substituted with single amino acids (proline, leucine and glutamic acid), granules at high salinity (20 g/L Na+) were not formed. This corresponded to a decrease of Methanosaeta relative abundance and a lack of compact clustering, together with disappearance of Defluviitaleaceae and consequent absence of bacterial filaments within the dispersed biomass. In these conditions, a biofilm was growing on the glass wall of the reactor instead, highlighting that a complex protein substrate such as tryptone can contribute to granules formation at elevated salinity.

    Anaerobic sludge granulation at high salinity
    Sudmalis, Dainis - \ 2020
    Wageningen University. Promotor(en): H.H.M. Rijnaarts; G. Zeeman, co-promotor(en): B.G. Temmink. - Wageningen : Wageningen University - ISBN 9789463952231 - 246

    Industries, such as leather tanning, agro-food, fisheries, petroleum, petrochemical and textile dyeing produce saline wastewater. As a result approximately 5% of the globally generated wastewater is hypersaline (salinity above 3.5%). Because salts have a negative effect on microbial activity, biological treatment processes are usually not considered for such wastewaters and they are treated with more expensive physical-chemical processes. Hence, there is a need to broaden the application of more sustainable biological treatment methods. In particular, anaerobic biological treatment should be considered due to possibility of converting organics into biogas, low energy requirements for operation, and production of small amounts of bio-solids.

    Amongst the anaerobic biological treatment technologies those based on formation of granular sludge are of special interest. This is due to superb settling velocities and a high methanogenic activity of the granules, which allows for a compact reactor design capable of handling high volumetric organic loading rates. Before this research, anaerobic granular sludge was reported to be unsuitable for treatment of highly saline wastewater because methanogens are inhibited by the salinity and sludge granules disintegrate/do not form. The main objective of this thesis was to accomplish anaerobic granulation at high salinity from dispersed biomass and to investigate strategies of overcoming salt toxicity to microorganisms.

    In Chapter 2 we investigated the possibility to form granules from dispersed biomass at low (5 g Na+/L) and high salinity (20 g Na+/L) in upflow anaerobic sludge blanket (UASB) reactors under other conditions known to improve fresh water granulation. The wastewater contained a complex, energy rich and proteinaceous substrate – a mixture of glucose, acetate and tryptone. This allowed a surprisingly fast development of anaerobic granules (within 45 days), even at 20 g Na+/L (~ 50 g/L NaCl). Although the COD (chemical oxygen demand, a measurement for organic pollution) removal efficiency was slightly better at 5 g Na+/L compared to 20 g Na+/L, at both salinities the removal efficiency exceeded 98% at organic loading rates as high as 16 g COD/L/d. To remain viable at high salinity, most prokaryotes synthesize or take up from bulk liquid small organic molecules called osmolytes. Uptake of osmolytes from bulk liquid is energetically more favourable compered to synthesis. Furthermore, it is known that methanogens mainly use nitrogen containing molecules, such as amino acids or their derivatives for osmoprotection. Also, extracellular polymeric substances (EPS) – the structural gluing material of granules - in anaerobic granular sludge consist of a large weight fraction of proteins (up to 90%). Thus, we hypothesized, that proteinaceous substrate in Chapter 2 potentially provided bioenergetically favourable synthesis precursors of osmolytes and EPS. This hypothesis was investigated in Chapters 3-5.

    In Chapter 3 proteins and amino acids were inspected for their potential to alleviate osmotic shock stress of acetoclastic methanogens in granular sludge. Aspartate, glutamate, gelatine and tryptone could all alleviate the negative effects of high salinity on methanogens. Furthermore, analysis of nitrogen containing osmolytes accumulated by salt adapted granular sludge revealed glutamate and N-acetyl-β-lysine as the major osmolytes. This could in part explain the positive effect of amino acids on methanogenic activity: glutamate could be taken up directly from the bulk liquid, while N-acetyl-β-lysine could be synthesized from aspartate after uptake in the cell. Hydrolysis of a protein (gelatine) and a peptide (tryptone) potentially could also provide both of these amino acids, thereby explaining their positive effect on methanogenic activity.

    In Chapter 4 the (positive) effect of proteinaceous substrates on the rate of anaerobic sludge granulation was investigated. In UASB reactor experiments, glucose and acetate were present in the wastewater, together with a third co-substrate that was different for each reactor. If proteinaceous compounds (tryptone or gelatine) were added as the third substrate, granulation at 20 g Na+/L already was observed after 40-50 days. With starch as the third substrate well settling granule-alike aggregates formed. However, this was only possible after a much longer period (~180 days) than with the proteinaceous substrate. Still, apparently methanogenic adaptation and sludge granulation can be achieved at high salinity even without addition of proteins implying that a broader spectrum of saline wastewater is amenable for anaerobic granular treatment without the need of protein dosing. In Chapter 5, the possibility to estimate the amount of proteinaceous substrate for enhanced granulation based on osmotic pressure calculations was studied. The experimental results agreed with calculations, which allowed for a nine fold decrease of protein concentration compared to the arbitrary chosen amounts in Chapter 2 and Chapter 4.

    In Chapter 6 microbial molecular and microscopy analyses revealed that in sludge granules of reactors supplied with proteinaceous substrate the dominant methanogenic archaea at two different salinities (5 and 20 g Na+/L) belonged to Methanosaeta in its filamentous form. Interestingly, also the dominant bacteria were present as filaments (Streptococcus at 5 g Na+/L and bacterium belonging to Defluvitaleaceae at 20 g Na+/L). An experiment was also performed in which the granulation at 20 g Na+/L from dispersed biomass was studied without a proteinaceous substrate, but with amino acids leucine and proline instead. In this reactor, the bacteria belonging to Defluvitaleaceae disappeared and the granulation was not achieved.

    In Chapter 7, ion exchange membranes were prepared with EPS extracted from high salinity adapted granules and shown to selectively transport cations and partially repel anions. Interestingly, EPS exhibited a higher selectivity for potassium transport compared to sodium, even though potassium and sodium have the same valence and similar physical-chemical properties. As potassium selectivity has commercial relevance, future studies focusing on the reason for this selectivity perhaps can result in the development of commercial potassium selective membranes. For microbial cells such improved transport of ions through EPS seems to have a negative effect. In methanogenic activity assays potassium was much more toxic compared to sodium suggesting that cation toxicity may be influenced by properties of EPS, i.e. the better the ion can diffuse through the EPS, the more toxic it is (Chapter 7). Finally, in Chapter 8 the results of this research are discussed in a broader context and future research directions are proposed.

    Regeneration and reuse of microbial extracellular polymers immobilised on a bed column for heavy metal recovery
    Ajao, Victor ; Nam, Kang ; Chatzopoulos, Paraschos ; Spruijt, Evan ; Bruning, Harry ; Rijnaarts, Huub ; Temmink, Hardy - \ 2020
    Water Research 171 (2020). - ISSN 0043-1354
    Biosorption - Column - Extracellular polymeric substances - Ion exchange mechanism - Metal adsorption

    Microbial extracellular polymeric substances (EPS) have gained increasing attention for various water treatment applications. In this study, EPS produced from nitrogen-limited glycerol/ethanol-rich wastewater were used to recover Cu2+ and Pb2+ from aqueous solutions. Continuous flow-through tests were conducted on a column packed with silica gel coated with polyethyleneimine, to which EPS were irreversibly attached as shown by optical reflectometry. These immobilised EPS excellently adsorbed Cu2+ and Pb2+, with 99.9% of influent metal adsorbed before the breakthrough points. Metal desorption was achieved with 0.1M HCl, with an average recovery of 86% for Cu2+ and 90% recovery for Pb2+. For the first time, we successfully showed the possibility to regenerate and reuse the immobilised EPS for five adsorption-desorption cycles (using Cu2+ as an example) with no reduction in the adsorbed amount at the breakthrough point (qbp). Based on the mass balance of the associated metal ions participating in the adsorption process, ion exchange was identified as the major mechanism responsible for Cu2+ and Pb2+ adsorption by EPS. The results demonstrate the potential of wastewater-produced EPS as an attractive and perhaps, cost-effective biosorbent for heavy metal removal (to trace effluent concentrations) and recovery (86–99%).

    Calcium effect on microbial activity and biomass aggregation during anaerobic digestion at high salinity
    Gagliano, Maria Cristina ; Sudmalis, Dainis ; Temmink, Hardy ; Plugge, Caroline M. - \ 2020
    New Biotechnology 56 (2020). - ISSN 1871-6784 - p. 114 - 122.
    Anaerobic digestion - Anaerobic granules - Ca - High salinity - Methanosaeta - Microbial aggregation

    The potential effect of different Ca2+ additions (150, 300, 450, 600 and 1000 mg/L) on microbial activity and aggregation, during anaerobic digestion at moderate (8 g/L Na+) and high salinity (20 g/L Na+) has been investigated. Batch tests were carried out in duplicate serum bottles and operated for 30 days at 37 °C. At 8 g/L Na+, methanogenic activity and protein degradation were comparable from 150 to 450 mg/L Ca2+, and a significant inhibition was only observed at a Ca2+concentration of 1000 mg/L. In contrast, at 20 g/L Na+, 150 to 300 mg/L were the only Ca2+ concentrations to maintain chemical oxygen demand (COD) removal, protein hydrolysis and methane production. Overall, increasing Ca2+ concentrations had a larger impact on acetotrophic methanogenesis at 20 g/L than at 8 g/L Na+. Increasing Ca2+ had a negative effect on the aggregation behaviour of the dominant methanogen Methanosaeta when working at 8 g/L Na+. At 20 g/L Na+ the aggregation of Methanosaeta was less affected by addition of Ca2+ than at 8 g/L Na+. The negative effect appeared to be connected with Ca2+ precipitation and its impact on cell-to cell communication. The results highlight the importance of ionic balance for microbial aggregation at high salinity, bringing to the forefront the effect on Methanosaeta cells, known to be important to obtain anaerobic granules.

    Sulfide induced phosphate release from iron phosphates and its potential for phosphate recovery
    Wilfert, P. ; Meerdink, J. ; Degaga, B. ; Temmink, H. ; Korving, L. ; Witkamp, G.J. ; Goubitz, K. ; Loosdrecht, M.C.M. van - \ 2020
    Water Research 171 (2020). - ISSN 0043-1354
    Iron - Phosphate recovery - Sewage sludge - Sulfide

    Sulfide is frequently suggested as a tool to release and recover phosphate from iron phosphate rich waste streams, such as sewage sludge, although systematic studies on mechanisms and efficiencies are missing. Batch experiments were conducted with different synthetic iron phosphates (purchased Fe(III)P, Fe(III)P synthesized in the lab and vivianite, Fe(II)3(PO4)2*8H2O), various sewage sludges (with different molar Fe:P ratios) and sewage sludge ash. When sulfide was added to synthetic iron phosphates (molar Fe:S = 1), phosphate release was completed within 1 h with a maximum release of 92% (vivianite), 60% (purchased Fe(III)P) and 76% (synthesized Fe(III)P). In the latter experiment, rebinding of phosphate to Fe(II) decreased net phosphate release to 56%. Prior to the re-precipitation, phosphate release was very efficient (P released/S input) because it was driven by Fe(III) reduction and not by, more sulfide demanding, FeSx formation. This was confirmed in low dose sulfide experiments without significant FeSx formation. Phosphate release from vivianite was very efficient because sulfide reacts directly (1:1) with Fe(II) to form FeSx, without Fe(III) reduction. At the same time vivianite-Fe(II) is as efficient as Fe(III) in binding phosphate. From digested sewage sludge, sulfide dissolved maximally 30% of all phosphate, from the sludge with the highest iron content which was not as high as suggested in earlier studies. Sludge dewaterability (capillary suction test, 0.13 ± 0.015 g2(s2m4)−1) dropped significantly after sulfide addition (0.06 ± 0.004 g2(s2m4)−1). Insignificant net phosphate release (1.5%) was observed from sewage sludge ash. Overall, sulfide can be a useful tool to release and recover phosphate bound to iron from sewage sludge. Drawbacks -deterioration of the dewaterability and a net phosphate release that is lower than expected-need to be investigated.

    Protein hydrolysis and fermentation under methanogenic and acidifying conditions
    Duong, Thu Hang ; Grolle, Katja ; Nga, Tran Thi Viet ; Zeeman, Grietje ; Temmink, Hardy ; Eekert, Miriam Van - \ 2019
    Biotechnology for Biofuels 12 (2019)1. - ISSN 1754-6834
    Amino acid fermentation - Hydrolysis - Methanogenic conditions - Non-methanogenic conditions - Proteins

    Background: Many kinds of wastewaters contain appreciable quantities of protein. Anaerobic processes are suitable for the treatment of wastewater high in organics to achieve pollution control and recovery of energy as methane and hydrogen, or intermediates for production of biofuels and valuable biochemicals. A distinction between protein hydrolysis and amino acid fermentation, especially for dissolved proteins, is needed to target which one is truly rate-limiting and to effectively harvest bioproducts during anaerobic conversion of these wastewaters. This study explored mesophilic anaerobic hydrolysis and amino acid fermentation of gelatine, as a model for dissolved proteins, at pH 7 and at pH 5. Results: The results showed that at pH 7, protein hydrolysis (first-order rate of 0.15 h-1) was approximately 5 times faster than acidification of the hydrolysis products (first-order rate of 0.03 h-1), implying that not hydrolysis but acidification was the rate-limiting step in anaerobic dissolved protein degradation. This was confirmed by (temporary) accumulation of amino acids. Nineteen different amino acids were detected during the first 8 incubation hours of gelatine at neutral pH and the total chemical oxygen demand (COD) of these 19 amino acids was up to approximately 40% of the COD of the gelatine that was added. Protein hydrolysis at pH 5 was 2-25 times slower than at pH 7. Shifting the initial pH from neutral to acidic conditions (pH 5) inhibited protein degradation and changed the volatile fatty acids (VFA) product profile. Furthermore, the presence or absence of methanogenic activity did not affect the rates of protein hydrolysis and acidification. Conclusions: The findings in this study can help to set a suitable solid retention time to accomplish anaerobic degradation of protein-rich wastewaters in continuous reactor systems. For example, if the target is harvesting VFAs, methanogens can be washed-out for a shorter retention time while amino acid fermentation, instead of hydrolysis as assumed previously, will govern the design and solutions to improve the system dealing with dissolved proteins.[Figure not available: see fulltext].

    Optimization of algae production on urine
    Tuantet, Kanjana ; Temmink, Hardy ; Zeeman, Grietje ; Wijffels, René H. ; Buisman, Cees J.N. ; Janssen, Marcel - \ 2019
    Algal Research 44 (2019). - ISSN 2211-9264
    Microalgae production - Nutrient removal - Photobioreactor control - Urine treatment

    Urine is a potential source of nutrients to grow microalgal biomass to be re-used as fertilizer and soil conditioner. In this study the impact of photobioreactor dilution rate on microalgae productivity and photosynthetic efficiency was assessed and used to determine operating conditions to reach both full nitrogen removal from urine and high biomass productivity. In addition, the possibility to work under day/night cycling was tested. To this end, the microalga Chlorella sorokiniana was grown on artificial urine and real human urine in bench-scale panel photobioreactors with short optical paths. At a light intensity of 1530 μmol⋅ m−2⋅s-1 photobioreactor productivity and photosynthetic efficiency was demonstrated to be maximal at reactor dilution rates between 0.10 and 0.15 h-1. A biomass yield of 1 g dry matter per mol of PAR photons was achieved. Biomass concentration, and accordingly nutrient removal efficiency, decreased at increasing reactor dilution rate. The experimental results could be reproduced by model simulations. These simulations allowed to demonstrate that the system must be operated at a dilution rate of less than 0.01 h-1 in order to reach complete nitrogen removal. In that scenario more than half of the potential biomass productivity is lost due to severe self-shading within the algal culture. Experiments with real human urine illustrated the problem of incomplete nitrogen removal and ammonium inhibition of growth at too high dilution rates. It is therefore suggested to apply an optimized pre-dilution of pure urine prior to treatment in a photobioreactor. Experiments under day-night cycles demonstrated that microalgal cultures quickly acclimate to such variable light conditions. Additional model simulations illustrated that a phototrophic system is most effective when diluted urine is fed to the photobioreactor during day time only. In that situation the lowest nitrogen concentration in the effluent can be reached at a maximal areal removal rate and photosynthetic efficiency.

    Textiel en porselein uit afvalwater halen
    Temmink, B.G. - \ 2019

    Ook online verschenen als: Kameleon-gel uit afvalwater goed voor potjes en stropdassen

    Valorization of glycerol/ethanol-rich wastewater to bioflocculants: recovery, properties, and performance
    Ajao, Victor ; Millah, Siti ; Gagliano, Maria Cristina ; Bruning, Harry ; Rijnaarts, Huub ; Temmink, Hardy - \ 2019
    Journal of Hazardous Materials 375 (2019). - ISSN 0304-3894 - p. 273 - 280.
    Biodegradable flocculants - Extracellular polymeric substance - Nitrogen limitation - Resource recovery

    Microbial extracellular polymeric substances (EPS)were produced in two membrane bioreactors, each separately treating fresh and saline synthetic wastewater (consisting of glycerol and ethanol), with the purpose of applying them as sustainable bioflocculants. The reactors were operated under nitrogen-rich (COD/N ratios of 5 and 20)and limited (COD/N ratios of 60 and 100)conditions. Under both conditions, high COD removal efficiencies of 87–96% were achieved. However, nitrogen limitation enhanced EPS production, particularly the polysaccharide fraction. The maximum EPS recovery (g EPS−COD/g COD influent )from the fresh wastewater was 54% and 36% recovery was obtained from the saline (30 g NaCl/L)wastewater. The biopolymers had molecular weights up to 2.1 MDa and anionic charge densities of 2.3–4.7 meq/g at pH 7. Using kaolin clay suspensions, high flocculation efficiencies of 85–92% turbidity removal were achieved at EPS dosages below 0.5 mg/g clay. Interestingly, EPS produced under saline conditions proved to be better flocculants in a saline environment than the corresponding freshwater EPS in the same environment. The results demonstrate the potential of glycerol/ethanol-rich wastewater, namely biodiesel/ethanol industrial wastewater, as suitable substrates to produce EPS as effective bioflocculants.

    The Effect of Bioinduced Increased pH on the Enrichment of Calcium Phosphate in Granules during Anaerobic Treatment of Black Water
    Cunha, Jorge Ricardo ; Tervahauta, Taina ; Weijden, Renata D. van der; Temmink, Hardy ; Hernández Leal, Lucía ; Zeeman, Grietje ; Buisman, Cees J.N. - \ 2018
    Environmental Science and Technology 52 (2018)22. - ISSN 0013-936X - p. 13144 - 13154.

    Simultaneous recovery of calcium phosphate granules (CaP granules) and methane in anaerobic treatment of source separated black water (BW) has been previously demonstrated. The exact mechanism behind the accumulation of calcium phosphate (Cax(PO4)y) in CaP granules during black water treatment was investigated in this study by examination of the interface between the outer anaerobic biofilm and the core of CaP granules. A key factor in this process is the pH profile in CaP granules, which increases from the edge (7.4) to the center (7.9). The pH increase enhances supersaturation for Cax(PO4)y phases, creating internal conditions preferable for Cax(PO4)y precipitation. The pH profile can be explained by measured bioconversion of acetate and H2, HCO3 - and H+ into CH4 in the outer biofilm and eventual stripping of CO2 and CH4 (biogas) from the granule. Phosphorus content and Cax(PO4)y crystal mass quantity in the granules positively correlated with the granule size, in the reactor without Ca2+ addition, indicating that the phosphorus rich core matures with the granule growth. Adding Ca2+ increased the overall phosphorus content in granules >0.4 mm diameter, but not in fine particles (<0.4 mm). Additionally, H+ released from aqueous phosphate species during Cax(PO4)y crystallization were buffered by internal hydrogenotrophic methanogenesis and stripping of biogas from the granule. These insights into the formation and growth of CaP granules are important for process optimization, enabling simultaneous Cax(PO4)y and CH4 recovery in a single reactor. Moreover, the biological induction of Cax(PO4)y crystallization resulting from biological increase of pH is relevant for stimulation and control of (bio)crystallization and (bio)mineralization in real environmental conditions.

    The potential of osmolytes and their precursors to alleviate osmotic stress of anaerobic granular sludge.
    Sudmalis, D. ; Millah, S.K. ; Gagliano, M.C. ; Butré, C.I. ; Plugge, C.M. ; Rijnaarts, H.H.M. ; Zeeman, G. ; Temmink, H. - \ 2018
    Water Research 147 (2018). - ISSN 0043-1354 - p. 142 - 151.
    Anaerobic granular sludge - Methanogenic activity - Osmolytes - Saline wastewater

    Increasing amounts of saline (waste)water with high concentrations of organic pollutants are generated globally. In the anaerobic (waste)water treatment domain, high salt concentrations are repeatedly reported to inhibit methanogenic activity and strategies to overcome this toxicity are needed. Current research focuses on the use of potential osmolyte precursor compounds for osmotic stress alleviation in granular anaerobic sludges upon exposure to hypersalinity shocks. Glutamic acid, aspartic acid, lysine, potassium, gelatine, and tryptone were tested for their potential to alleviate osmotic stress in laboratory grown and full – scale granular sludge. The laboratory grown granular sludge was adapted to 5 (R5) and 20 (R20) g Na+/L. Full-scale granular sludge was obtained from internal circulation reactors treating tannery (waste)water with influent conductivity of 29.2 (Do) and 14.1 (Li) mS/cm. In batch experiments which focused on specific methanogenic activity (SMA), R5 granular sludge was exposed to a hypersalinity shock of 20 g Na+/L. The granular sludge of Do and Li was exposed to a hypersalinity shock of 10 g Na+/L with sodium acetate as the sole carbon source. The effects on R20 granular sludge were studied at the salinity level to which the sludge was already adapted, namely 20 g Na+/L. Dosing of glutamic acid, aspartic acid, gelatine, and tryptone resulted in increased SMA compared to only acetate fed batches. In batches with added glutamic acid, the SMA increased by 115% (Li), 35% (Do) and 9% (R20). With added aspartic acid, SMA increased by 72% (Li), 26% (Do), 12% (R5) and 7% (R20). The addition of tryptone resulted in SMA increases of 36% (R5), 17% (R20), 179% (Li), and 48% (Do), whereas added gelatine increased the SMA by 30% (R5), 14% (R20), 23% (Li), and 13% (Do). The addition of lysine, meanwhile, gave negative effects on SMA of all tested granular sludges. Potassium at sea water Na/K ratio (27.8 w/w) had a slight positive effect on SMA of Do (7.3%) and Li (10.1%), whereas at double the sea water ratio (13.9% w/w) had no pronounced positive effect. R20 granular sludge was also exposed to hyposalinity shock from 20 down to 5 g Na+/L. Glutamate and N-acetyl-β-lysine were excreted by microbial consortium in anaerobic granular sludge adapted to 20 g Na+/L upon this exposure to hyposalinity. A potential consequence when applying these results is that saline streams containing specific and hydrolysable proteins can be anaerobically treated without additional dosing of osmolytes.

    Biological treatment of produced water coupled with recovery of neutral lipids
    Sudmalis, D. ; Silva, P. da; Temmink, H. ; Bijmans, M.M. ; Pereira, M.A. - \ 2018
    Water Research 147 (2018). - ISSN 0043-1354 - p. 33 - 42.
    Alkane biodegradation - Biological treatment - Neutral lipids production - Produced water

    Produced water (PW) is the largest waste stream generated by oil and gas industry. It is commonly treated by physical-chemical processes due to high salt content and poor biodegradability of water insoluble compounds, such as n-alkanes. N-alkanes can represent a major fraction of organic contaminants within PW. In this study the possibility of simultaneous n – alkane biodegradation and production of neutral lipids in a concentrated PW stream with A. borkumenis SK2 as the sole reactor inoculum was investigated. N-alkane removal efficiency up to 99.6%, with influent alkane COD of 7.4 g/L, was achieved in a continuously operated reactor system. Gas chromatography results also showed that the majority of other non-polar compounds present in the PW were biodegraded. Biodegradation of n-alkanes was accompanied by simultaneous production of neutral lipids, mostly wax ester (WE)-alike compounds. We demonstrate, that under nutrient limited conditions and 108.9 ± 3.3 mg/L residual n-alkane concentration the accumulation of extracellular WE-alike compounds can be up to 12 times higher compared to intracellular, reaching 3.08 grams per litre of reactor volume (g/Lreactor) extracellularly and 0.28 g/Lreactor intracellularly. With residual n-alkane concentration of 311.5 ± 34.2 mg/L accumulation of extracellular and intracellular WE-alike compounds can reach up to 6.15 and 0.91 g/Lreactor, respectively. To the best of our knowledge simultaneous PW treatment coupled with production of neutral lipids has never been demonstrated before.

    Understanding and improving the reusability of phosphate adsorbents for wastewater effluent polishing
    Suresh Kumar, Prashanth ; Ejerssa, Wondesen Workneh ; Wegener, Carita Clarissa ; Korving, Leon ; Dugulan, Achim Iulian ; Temmink, Hardy ; Loosdrecht, Mark C.M. van; Witkamp, Geert-Jan - \ 2018
    Water Research 145 (2018). - ISSN 0043-1354 - p. 365 - 374.
    Calcium adsorption - Phosphate adsorption - Regeneration - Reusability - Surface precipitation - Wastewater effluent

    Phosphate is a vital nutrient for life but its discharge from wastewater effluents can lead to eutrophication. Adsorption can be used as effluent polishing step to reduce phosphate to very low concentrations. Adsorbent reusability is an important parameter to make the adsorption process economically feasible. This implies that the adsorbent can be regenerated and used over several cycles without appreciable performance decline. In the current study, we have studied the phosphate adsorption and reusability of commercial iron oxide based adsorbents for wastewater effluent. Effects of adsorbent properties like particle size, surface area, type of iron oxide, and effects of some competing ions were determined. Moreover the effects of regeneration methods, which include an alkaline desorption step and an acid wash step, were studied. It was found that reducing the adsorbent particle size increased the phosphate adsorption of porous adsorbents significantly. Amongst all the other parameters, calcium had the greatest influence on phosphate adsorption and adsorbent reusability. Phosphate adsorption was enhanced by co-adsorption of calcium, but calcium formed surface precipitates such as calcium carbonate. These surface precipitates affected the adsorbent reusability and needed to be removed by implementing an acid wash step. The insights from this study are useful in designing optimal regeneration procedures and improving the lifetime of phosphate adsorbents used for wastewater effluent polishing.

    Editorial: Algal technologies for wastewater treatment and resource recovery :
    Muñoz, Raul ; Temmink, Hardy ; Verschoor, Anthony M. ; Steen, Peter Van Der - \ 2018
    Water Science and Technology 78 (2018)1. - ISSN 0273-1223 - 2 p.
    Ons dagelijks (afval)water
    Temmink, B.G. - \ 2018
    In: Afvalwater / van Loosdrecht, Mark, Stams, Alfons, Hoekstra, Wiel, van de Graaf, Astrid, Den Haag : Stichting BWM - ISBN 9789073196902 - p. 23 - 28.
    Effect of low concentrations of dissolved oxygen on the activity of denitrifying methanotrophic bacteria
    Kampman, Christel ; Piai, Laura ; Temmink, Hardy ; Hendrickx, Tim L.G. ; Zeeman, Grietje ; Buisman, Cees J.N. - \ 2018
    Water Science and Technology 77 (2018)11. - ISSN 0273-1223 - p. 2589 - 2597.
    Anaerobic methane oxidation - Anaerobic wastewater treatment - Denitrification - Methylomirabilis oxyfera - Oxygen

    Chemical energy can be recovered from municipal wastewater as biogas through anaerobic treatment. However, effluent from direct anaerobic wastewater treatment at low temperatures still contains ammonium and substantial amounts of dissolved CH4. After nitritation, CH4 can be used as electron donor for denitrification by the anaerobic bacterium Candidatus Methylomirabilis oxyfera. The effect of 0.7% (0.35 mg dissolved O2/L), 1.1% (0.49 mg dissolved O2/L), and 2.0% (1.0 mg dissolved O2/L), on denitrifying activity was tested. Results demonstrated that at 0.7% O2, denitrifying methanotrophic activity slightly increased and returned to its original level after O2 had been removed. At 1.1% O2, CH4 consumption rate increased 118%, nitrite consumption rate increased 58%. After removal of O2, CH4 consumption rate fully recovered, and nitrite consumption rate returned to 88%. These indicate that traces of O2 that bacteria are likely to be exposed to in wastewater treatment are not expected to negatively affect the denitrifying methanotrophic process. The presence of 2.0% O2 inhibited denitrifying activity. Nitrite consumption rate decreased 60% and did not recover after removal of O2. No clear effect on CH4 consumption was observed.

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