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.

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A research challenge vision regarding management of agricultural waste in a circular bio-based economy
Gontard, Nathalie ; Sonesson, Ulf ; Birkved, Morten ; Majone, Mauro ; Bolzonella, David ; Celli, Annamaria ; Angellier-Coussy, Hélène ; Jang, Guang Way ; Verniquet, Anne ; Broeze, Jan ; Schaer, Burkhard ; Batista, Ana Paula ; Sebok, András - \ 2018
Critical Reviews in Environmental Science and Technology 48 (2018)6. - ISSN 1064-3389 - p. 614 - 654.
Agriculture - bio-based materials - biogas - circular economy - eco-design - waste

Agricultural waste is a huge pool of untapped biomass resources that may even represent economic and environmental burdens. They can be converted into bioenergy and bio-based products by cascading conversion processes, within circular economy, and should be considered residual resources. Major challenges are discussed from a transdisciplinary perspective, focused on Europe situation. Environmental and economic consequences of agricultural residue management chains are difficult to assess due to their complexity, seasonality and regionality. Designing multi-criteria decision support tools, applicable at an early-stage of research, is discussed. Improvement of Anaerobic Digestion (AD), one of the most mature conversion technologies, is discussed from a technological point of view and waste feedstock geographical and seasonal variations. Using agricultural residual resources for producing high-value chemicals is a considerable challenge analysed here, taking into account innovative eco-efficient and cost-effective cascading conversion processes (bio-refinery concept). Moreover, the promotion of agricultural residues-based business is discussed through industrial ecology, to promote synergy, on a local basis, between different agricultural and industrial value chains. Finally, to facilitate a holistic approach and optimise materials and knowledge flows management, the connection of stakeholders is discussed to promote cross-sectorial collaboration and resource exchange at appropriate geographic scales.

Destructive creation : capital accumulation and the structural violence of tourism
Büscher, Bram ; Fletcher, Robert - \ 2017
Journal of Sustainable Tourism 25 (2017)5. - ISSN 0966-9582 - p. 651 - 667.
capital - inequality - Tourism - value - violence - waste

Tourism is not merely a capitalist practice but a central practice through which capitalism sustains itself. Precisely how tourism “products” become capital and the types of violence this process entails, however, has not yet been systematically theorized or investigated. Building on Noel Castree's six principles of commodification, we explore how tourism becomes capital, understood as “value in motion”, and how this process not only provokes various forms of material violence but can become a form of (structural) violence in its own right. Based on research in tourism settings in Southern Africa and Latin America and general trends in international tourism, we argue that three integrated forms of structural violence to both humans and non-human natures are especially prominent, namely the systematic production of inequalities, waste and “spaces of exception”. As a global industry crucially dependent on integrated material and discursive forms of value creation, we also show that these forms of structural violence are often rendered invisible through branding. We conclude that tourism uniquely combines these three forms of structural violence to enable a move from Schumpeter's famous creative destruction to “destructive creation” as a key form of violence under capitalism.

Enhancement of soil suppressiveness against Rhizoctonia solani in sugar beet by organic amendments
Postma, J. ; Schilder, M.T. - \ 2015
Applied Soil Ecology 94 (2015). - ISSN 0929-1393 - p. 72 - 79.
bacterial communities - nematode control - diversity - rhizosphere - variability - microflora - pathogens - fusarium - diseases - waste
The efficacy of different organic soil amendments on disease suppression to Rhizoctoniasolani AG 2-2IIIB was tested in a bio-assay with sugar beet as a test plant. Lysobacter populations in soil were quantified as a possible mechanism for disease suppression. Disease spread through the bio-assay tank was significantly reduced up to 86, 83, 52, and 48% after amending the non-sterilized soil with yeast or chitin at a rate of 0.3% (w/w) in consecutive experiments. Inexpensive protein-rich waste products from food industry (i.e., feather, hoof, meat, blood and fish meal) also effectively increased Rhizoctonia-disease suppression. Several plant-derived products (e.g., spent mushroom compost, dried algae, spent brewer’s grain, Brassica seed meal) were not effective. Lysobacter populations naturally present in the soil were increased 3–10 fold (measured by a TaqMan quantitative PCR) in soils amended with organic compounds that stimulated Rhizoctonia-disease suppression. The role of Lysobacter as a key factor in Rhizoctonia-disease suppression, however, could not be confirmed by adding Lysobacter isolates to a sterilized soil amended with yeast or chitin. Hence, we hypothesize that unexplored biological factors were involved in disease suppression, since the tested soil became conducive after gamma-sterilization. The consistent enhancement of Rhizoctonia-disease suppression in sugar beet with yeast and chitin amendments, and the efficacy of inexpensive protein-rich waste products such as feather meal and hoof meal in our bio-assays, warrants further study in field experiments
Toward concise metrics for the production of chemicals from renewable biomass
Sheldon, R.A. ; Sanders, J.P.M. - \ 2015
Catalysis today 239 (2015). - ISSN 0920-5861 - p. 3 - 6.
eco-efficiency analysis - green chemistry - organic-synthesis - atom economy - catalysis - future - routes - waste - basf
The development of a set of sustainability metrics for quickly evaluating the production of commodity chemicals from renewable biomass is described. The method is based on four criteria: material and energy efficiency, land use and process economics. The method will be used for comparing the sustainability of the production of seven commodity chemicals – lactic acid, 1-butanol, propylene glycol, succinic acid, acrylonitrile, isoprene and methionine – from fossil feedstocks (crude oil or natural gas) versus renewable biomass.
Optimizing the performance of a reactor by reducing the retention time and addition of glycerin for anaerobically digesting manure
Timmerman, M. ; Schuman, E. ; Eekert, M. ; Riel, J.W. van - \ 2015
Environmental Technology 36 (2015)10. - ISSN 0959-3330 - p. 1223 - 1236.
co-digestion - methane production - crude glycerin - cattle manure - biogas - waste - biogasification - inhibition - ammonia
Anaerobic digestion of manure is a widely accepted technology for energy production. However, only a minimal portion of the manure production in the EU is anaerobically digested and occurs predominantly in codigestion plants. There is substantial potential for biogas plants that primarily operate on manure (>90%); however, the methane yields of manure are less compared to coproducts, which is one of the reasons for manure-based biogas plants often being economically non-viable. Therefore, it is essential to begin increasing the efficiency of these biogas plants. This study investigated the effect of decreasing retention time and introducing a moderate amount of glycerin on the biogas production as methods to improve efficiency. An experiment has been conducted with two different manure types in four biogas reactors. The results of the study demonstrated that, first, it was possible to decrease the retention time to 10–15 days; however, the effect on biogas production varied per manure type. Secondly, the biogas production almost triples at a retention time of 15.6 days with an addition of 4% glycerin. The relative production-enhancing effect of glycerin did not vary significantly with both manure types. However, the absolute production-enhancing effect of glycerin differed per manure type since the biogas production per gram VS differed per manure type. Thirdly, the positive effect of the glycerin input declines with shorter retention times. Therefore, the effect of glycerin addition depends on the manure type and retention time.
Input materials and processing conditions control compost dissolved organic carbon quality
Straathof, A.L. ; Comans, R.N.J. - \ 2015
Bioresource Technology 179 (2015). - ISSN 0960-8524 - p. 619 - 623.
maturity - stability - parameters - fractions - matter - waste
Dissolved organic carbon (DOC) has been proposed as an indicator of compost maturity and stability. Further fractionation of compost DOC may be useful for determining how particular composting conditions will influence DOC quality. Eleven composts ranging in input materials and processing techniques were analyzed; concentrations of DOC ranged from 428 mg kg-1 to 7300 mg kg-1. Compost DOC was qualified by fractionation into pools of humic acids (HA), fulvic acids (FA), hydrophobic neutrals (HoN), and hydrophilic (Hi) compounds. The range in proportion of DOC pools was highly variable, even for composts with similar total DOC concentrations. Longer composting time and higher temperatures consistently corresponded with a depletion of hydrophilics, suggesting a preferential turnover of these compounds during the thermophilic composting phase. Qualification of DOC pools through fractionation may be an informative tool in predicting the effects of a processing technique on compost quality and, ultimately, soil functional processes.
The "dark side" of food banks? Exploring emotional responses of food bank receivers in the Netherlands
Horst, H.M. van der; Pascucci, S. ; Bol, W. - \ 2014
British Food Journal 116 (2014)9. - ISSN 0007-070X - p. 1506 - 1520.
shame - guilt - insecurity - assistance - poverty - waste - work
Purpose – The purpose of this paper is to address how food, social status as well as the interactions at the food bank induce emotions in receivers, such as shame, gratitude and anger. Since early 2000s a steadily growing number of low-income and/or over-indebted households in the Netherlands alleviate their situation with food donations from local food banks. Such food banks collect from companies edible food that would otherwise have gone to waste. The growing demand for food assistance indicates it is a welcome contribution to the groceries in many households. However, receiving food assistance as well as eating the products forces the receivers to set aside embodied dispositions towards food and norms about how to obtain food. Furthermore, it places them in interactions of charitable giving that may be harmful to the self-esteem of receivers. Design/methodology/approach – The paper is based on a qualitative study at a food bank in the Netherlands, consisting among others of in-depth interviews with 17 receivers of food assistance, observations and several interviews with volunteers. Findings – Of all emotions that were expressed during the interviews, shame appeared as the most prominent. Particularly issues of shame emerged in relation to all three food-bank-related experiences: the content of the crate, the interaction with volunteers and lastly the understanding of one’s positioning in a social hierarchy. While shame can be a very private emotion – even talking about being ashamed can be shameful – it is also an utterly social emotion. Originality/value – This research is among the few ones explicitly addressing emotional emotions related to receivers in food bank.
Effect and key factors of byproducts valorization: the case of dairy industry
Banaszewska, A. ; Cruijssen, F.C.A.M. ; Claassen, G.D.H. ; Vorst, J.G.A.J. van der - \ 2014
Journal of Dairy Science 97 (2014)4. - ISSN 0022-0302 - p. 1893 - 1908.
whey - proteins - waste
Production of many consumer products results in byproducts that contain a considerably large part of nutrients originating from input materials. High production volumes, environmental impact, and nutritional content of byproducts make them an important subject for careful valorization. Valorization allows us to explore the possibility of reusing nutrients in the production of main products, and thus highlights the potential gains that can be achieved. The main aim of this study was to evaluate the added value of cheese whey valorization, and to determine the impact of integral valorization of main products and byproducts on the profit of a dairy producer. Several scenarios and cases were implemented and analyzed using a decision support tool, the integral dairy valorization model. Data originated from the international dairy processor FrieslandCampina (Amersfoort, the Netherlands). The outcomes of scenarios were analyzed with regard to profit and shifts in the production of nonwhey end products, and were validated by company experts. Modeling results showed that the valorization of byproducts is very profitable (24.3% more profit). Furthermore, additional profit can be achieved when 2 valorization processes (main products and byproducts) are integrated. This effect is, however, considerably affected by current capacity and market demand limitations. Significant benefits can be created if demand of whey-based products is increased by 25%
Biodiesel and biohydrogen production from cotton-seed cake in biorefinery concept
Panagiotopoulos, I.A. ; Pasias, S. ; Bakker, R.R.C. ; Vrije, G.J. de; Papayannakos, N. ; Claassen, P.A.M. ; Koukios, E.G. - \ 2013
Bioresource Technology 136 (2013). - ISSN 0960-8524 - p. 78 - 86.
thermophile caldicellulosiruptor-saccharolyticus - dilute-acid pretreatment - hydrogen-production - extreme thermophile - vegetable-oils - barley straw - thermotoga-neapolitana - inhibitory compounds - hydrolysis - waste
Biodiesel production from cotton-seed cake (CSC) and the pretreatment of the remaining biomass for dark fermentative hydrogen production was investigated. The direct conversion to biodiesel with alkali free fatty acids neutralization pretreatment and alkali transesterification resulted in a biodiesel with high esters content and physicochemical properties fulfilling the EN-standards. Blends of cotton-seed oil methyl esters (CME) and diesel showed an improvement in lubricity and cetane number. Moreover, CME showed good compatibility with commercial biodiesel additives. On the basis of conversion of the remaining CSC to sugars fermentable towards hydrogen, the optimal conditions included removal of the oil of CSC and pretreatment at 10% NaOH (w/w dry matter). The extreme thermophilic bacterium Caldicellulosiruptor saccharolyticus showed good hydrogen production, 84–112% of the control, from NaOH-pretreated CSC and low hydrogen production, 15–20% of the control, from the oil-rich and not chemically pretreated CSC, and from Ca(OH)2-pretreated CSC.
Assessing phosphate rock depletion and phosphorus recycling options
Koppelaar, R.H.E.M. ; Weikard, H.P. - \ 2013
Global environmental change : human and policy dimensions 23 (2013)6. - ISSN 0959-3780 - p. 1454 - 1466.
economics - perspective - benefits - biomass - waste - flows
We analyze global elemental phosphorus flows in 2009 for (1) mining to products, (2) animal and human manure flows, (3) crop harvests and animal production, (4) food production, (5) soil erosion, (6) and crop uptake. Informed by the flow assessment the potential and cost of phosphorus usage reduction and recycling measures are quantified, and fed into a constructed phosphorus supply-demand model with reserve assessment to assess the impact of these measures on phosphate rock resource availability. According to our results in 2009 globally 21.4 Mt elemental phosphorus from rock phosphate was consumed in products of which 17.6 Mt used as fertilizers, fully able to cover erosion losses and outputs in agriculture in aggregate, but insufficient from the perspective of bio-available phosphorus in soils. We find substantial scope for phosphorus use reduction, at potentially 6.9 Mt phosphorus, or 32% of 2009 phosphate rock supply. Another 6.1 Mt, or 28% can technologically be recycled from waterways and wastewater, but at a cost substantially above any foreseeable phosphate rock fertilizer price. The model results suggests phosphate rock reserves are sufficient to meet demand into the 22nd century, and can be extended well into the 23rd century with assessed use reduction and recycling measures
Chain elongation of acetate and ethanol in an upflow anaerobic filter for high rate MCFA production
Grootscholten, T.I.M. ; Steinbusch, K.J.J. ; Hamelers, H.V.M. ; Buisman, C.J.N. - \ 2013
Bioresource Technology 135 (2013). - ISSN 0960-8524 - p. 440 - 445.
mixed cultures - liquid fuels - reactor - digestion - caproate - hydrogen - biomass - waste
Recently, interest has regained for medium chain fatty acids (MCFAs) as a low cost feedstock for bio-based chemical and fuel production processes. To become cost-effective, the volumetric MCFA production rate by chain elongation should increase to comparable rates of other fermentation processes. We investigate the MCFA production process at a hydraulic retention time of 17 h in an upflow anaerobic filter to improve the volumetric MCFA production rate. This approach resulted in a MCFA production with a volumetric production rate of 16.6 g l-1 d-1, which is more than seven times higher than the current production rate. Moreover the rate is now in the range of other fermentation processes like methane, butanol and ethanol production. Increasing the ethanol load lead to higher volumetric production rates and a high MCFA selectivity of 91%. During operation, methane percentages lower than 0.1% were detected in the headspace of reactor.
Effect of ammonia on the anaerobic hydrolysis of cellulose and tributyrin
Vasconcelos Fernandes, T. ; Keesman, K.J. ; Zeeman, G. ; Lier, J.B. van - \ 2012
Biomass and Bioenergy 47 (2012). - ISSN 0961-9534 - p. 316 - 323.
thermophilic digestion - methanogenic sludge - bounded noise - cow manure - kinetics - inhibition - nitrogen - identification - waste
Ammonia nitrogen is one of the most common inhibitors in the anaerobic digestion of complex wastes containing high concentrations of ammonia like animal manures, blackwater and waste oil from gastronomy. The inhibiting effect of ammonia on methanogenesis has been well established. In contrast, the knowledge on the effect of ammonia on organic matter hydrolysis is rather limited. This study focuses on evaluating the effect of ammonia on the hydrolysis of carbohydrates and lipids, which are commonly found in biomass. Batch digestion of tributyrin and cellulose at varying ammonia concentrations were performed, using biomass adapted to 4.9 g NH4+–N.l-1. From this experimental study it was concluded that total ammonia nitrogen in the range of 2.4–7.8 g NH4+–N.l-1 (283–957 mg NH3–N.l-1) does not inhibit the hydrolysis of tributyrin or cellulose. This result is further confirmed by mathematical analysis of the estimated variation of the first-order hydrolysis constant as a function of the total ammonia concentration.
Small-scale processing of biomass for biorefinery
Bruins, M.E. ; Sanders, J.P.M. - \ 2012
Biofuels Bioproducts and Biorefining 6 (2012)2. - ISSN 1932-104X - p. 135 - 145.
bulk chemicals - cost - economy - heat - energy - waste - plant - water - power
The current fossil-based economy is moving towards a more bio-based economy. To enable this transition, many different processes for biorefinery are being developed. Small-scale biorefinery processes can be beneficial, not only socially and ecologically, but also economically. The main motivation for small-scale biorefinery is local re-use of materials, like water, minerals, organic matter, CO2, and heat. This minimizes costs for recycling and transport. A smart and integrated process design can beat the advantages of economy of scale applied in large-scale processes. Examples of two fully operational small-scale systems that produce ethanol and starch are given to illustrate our theory. Specific design rules for small-scale biorefineries are defined. The focus in design for small-scale processes should be on minimizing capital costs. Moreover, it is shown that separation of relatively simple pre-processing at small decentralized and more capital-intensive processing at large centralized factories, respectively, is advantageous. Integration with a biogas and combined heat and power (CHP) unit will furthermore allow usage of residual material to produce energy needed in the rest of the process
Use of Avoidance Tests for Investigating Potential of the Earthworm Eisenia fetida to Improve Composting of Grass Clippings
Illmer, P. ; Liebensteiner, M. - \ 2011
Compost Science & Utilization 19 (2011)2. - ISSN 1065-657X - p. 123 - 128.
waste - efficiency - quality - savigny - soil
The earthworm Eisenia fetida is the most commonly used worm for worm-supported composting of organic residues. Within the present study, the potential of E. fetida for decomposing grass clippings, an organic waste which usually causes anoxic conditions and thus insufficient degradation in the course of common composting, was investigated. To enable a thorough investigation, the substrate-related requirements of E. fetida were studied using so-called avoidance tests. These tests provide a sensitive method for evaluating the preferences and aversions of soil animals related to substrate ingredients in a sublethal range. E. fetida favored relatively moist soil with about 70% of the WHC(max) and the most preferred concentration of fresh grass clippings within soil was 15% (v/v). Pretreatments of the grass clippings like silage, precomposting or inoculation with the fungi Trichoderma viride and Geotrichum klebahnii were investigated and point to an increased tolerance of the worms against pre-composted and inoculated grass whereas ensiled grass and remoistened hay was avoided. The optimum concentration of ammonium for E. fetida was 18 mu g NH(4)(+)-N g(-1) DW soil although the worms could withstand much higher concentrations. Lactic and acetic acid, intermediates that are quickly released from fresh lawn clippings under oxygen lacking conditions, were indicated to be the most important factors for preventing worms from tolerating higher concentrations of grass clippings.
Emergence of suspected type D botulism in ruminants in England and Wales (2001-2009), associated with exposure to broiler litter.
Payne, J.H. ; Hogg, R.A. ; Otter, A. ; Roest, H.I.J. ; Livesey, C.T. - \ 2011
Veterinary Record 168 (2011)24. - ISSN 0042-4900
poultry litter - clostridium-perfringens - necrotic enteritis - fsa advice - b botulism - cattle - waste - sheep - inhibition - diagnosis
Scanning surveillance by the Veterinary Laboratories Agency revealed the emergence of suspected botulism in ruminants in 2003, presented as flaccid paralysis. From 2003 to 2009, 168 cattle and 19 sheep incidents were recorded, with mortality between 5 and 80 per cent. All sheep incidents and 95 per cent of cattle incidents had proximity to broiler litter. From July 2006, the gut contents collected from 74 affected cattle and 10 affected sheep were tested for Clostridium botulinum toxins using mice bioassays and for organisms by culture. Type D toxin was identified in 32 per cent of cattle and 18 per cent of sheep samples. C botulinum type D organisms were identified in 40 per cent of cattle and 30 per cent of sheep samples, but broth from one sample reacted with C and D antisera. Type C botulism has previously been reported more commonly than type D in the UK and has been associated with the use of poultry litter as fertiliser, bedding or feed. The almost exclusive association with C botulinum type D toxins or organisms in the gut contents in this survey suggests a change in the source or epidemiology of botulism in the UK. The source of C botulinum type D was uncertain. Broilers may carry C botulinum type D in their gut flora subclinically. The emergence of a new type D strain, or changes in broiler husbandry and nutrition, medication and other enteric infections may have affected colonisation with C botulinum. Further investigation of poultry and farm environments for sources of type D awaits the development of tests for C botulinum toxins that do not require the use of mice
Improving ruminal degradability of oil palm fronds using white rot fungi
Rahman, M.M. ; Lourenco, M. ; Hassim, H.A. ; Baars, J.J.P. ; Sonnenberg, A.S.M. ; Cone, J.W. ; Boever, J.L. de; Fievez, V. - \ 2011
Animal Feed Science and Technology 169 (2011)3-4. - ISSN 0377-8401 - p. 157 - 166.
in-vitro digestibility - chemical-composition - wheat-straw - cattle feed - substrate - fermentation - lignin - waste - plant
The use of oil palm fronds (OPF) in livestock production is limited as up to 0.20 of their dry biomass is lignin. White rot fungi (WRF) are very effective basidiomycetes for biological pre-treatment as they degrade lignin extensively. Ten WRF were screened for their potential to increase OPF digestibility, which were colonized with one of the 10 WRF for 3 or 9 wks at 30 °C. After colonization, weight loss, neutral detergent fiber, acid detergent fiber, lignin(pm), cellulose, crude protein and ash were determined. Further, in vitro gas production was determined using rumen fluid either, or not, adapted to OPF. Finally, in vitro degradability of organic matter was determined using cellulase. Results showed that longer colonization was associated with higher dry matter (DM) losses. Phanerochaete chrysosporium had the highest weight loss, whereas OPF colonized for 9 wks with Ceriporiopsis subvermispora, Pleurotus ostreatus, Phlebia brevispora, Lentinula edodes, Pleurotus eryngii and Trametes versicolor had the highest lignin(pm) degradation. Treatments with the highest lignin(pm) loss, rather than selective lignin(pm) degradation, had the most potential to increase in vitro gas or volatile fatty acid production. Nevertheless, total lignin(pm) loss explained only 0.60 of the variation in in vitro DM degradability. It appeared that within the selected group of fungi which had the highest lignin(pm) degradation (i.e., C. subvermispora, Ganoderma lucidum, L. edodes, P. brevispora and P. eryngii), additional cellulose degradation was essential to substantially increase in vitro DM degradability either with rumen fluid adapted, or not, to OPF. C. subvermispora (3 wks) and L. edodes and P. brevispora (9 wks) were most promising for OPF pre-treatment, but relatively high biomass losses during fungi colonization need further research attention.
Harvesting of microalgae by bio-flocculation
Salim, S. ; Bosma, R. ; Vermuë, M.H. ; Wijffels, R.H. - \ 2011
Journal of Applied Phycology 23 (2011)5. - ISSN 0921-8971 - p. 849 - 855.
algae - efficiency - waste
The high-energy input for harvesting biomass makes current commercial microalgal biodiesel production economically unfeasible. A novel harvesting method is presented as a cost and energy efficient alternative: the bio-flocculation by using one flocculating microalga to concentrate the non-flocculating microalga of interest. Three flocculating microalgae, tested for harvesting of microalgae from different habitats, improved the sedimentation rate of the accompanying microalga and increased the recovery of biomass. The advantages of this method are that no addition of chemical flocculants is required and that similar cultivation conditions can be used for the flocculating microalgae as for the microalgae of interest that accumulate lipids. This method is as easy and effective as chemical flocculation which is applied at industrial scale, however in contrast it is sustainable and cost-effective as no costs are involved for pre-treatment of the biomass for oil extraction and for pre-treatment of the medium before it can be re-used
Evidence of Increasing Antibiotic Resistance Gene Abundances in Archived Soils since 1940
Knapp, C.W. ; Dolfing, J. ; Ehlert, P.A.I. ; Graham, D.W. - \ 2010
Environmental Science and Technology 44 (2010)2. - ISSN 0013-936X - p. 580 - 587.
real-time pcr - spectrum beta-lactamases - staphylococcus-aureus - klebsiella-pneumoniae - rapid identification - fluorescence pcr - tetracycline - diversity - waste - environment
Mass production and use of antibiotics and antimicrobials in medicine and agriculture have existed for over 60 years, and has substantially benefited public health and agricultural productivity throughout the world, However, there is growing evidence that resistance to antibiotics (AR) is increasing both in benign and pathogenic bacteria, posing an emerging threat to public and environmental health in the future. Although evidence has existed for years from clinical data of increasing AR, almost no quantitative environmental data exist that span increased industrial antibiotic production in the 1950s to the present, i.e., data that might delineate trends in AR potentially valuable for epidemiological studies. To address this critical knowledge gap, we speculated that AR levels might be apparent in historic soil archives as evidenced by antibiotic resistance gene (ARG) abundances over time. Accordingly, DNA was extracted from five long-term soil-series from different locations in The Netherlands that spanned 1940 to 2008, and 16S rRNA gene and 18 ARG abundances from different major antibiotic classes were quantified. Result; show that ARG from all classes of antibiotics tested have significantly increased since 1940, but especially within the tetracyclines, with some individual ARG being > 15 times more abundant now than in the 1970s. This is noteworthy because waste management procedures have broadly improved and stricter rules on nontherapeutic antibiotic use in agriculture are being promulgated. Although these data are local to The Netherlands, they suggest basal environmental levels of ARG still might be increasing, which has implications to similar locations around the world.
Biohydrogen production from untreated and hydrolyzed potato steam peels by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana
Mars, A.E. ; Veuskens, T. ; Budde, M.A.W. ; Doeveren, P.F.N.M. van; Lips, S.J.J. ; Bakker, R.R. ; Vrije, G.J. de; Claassen, P.A.M. - \ 2010
International Journal of Hydrogen Energy 35 (2010)15. - ISSN 0360-3199 - p. 7730 - 7737.
fermentative hydrogen-production - sp-nov - starch - bacterium - waste - microflora - substrate
Production of hydrogen by the extreme thermophiles Caldicellulosiruptor saccharolyticus and Thermotoga neapolitana was studied in serum flasks and in pH-controlled bioreactors with glucose, and hydrolyzed and untreated potato steam peels (PSP) as carbon sources. Two types of PSP hydrolysates were used: one in which the starch in the PSP was liquefied with alpha-amylase, and one in which the liquefied starch was further hydrolyzed to glucose by amyloglucosidase. When the PSP hydrolysates or untreated PSP were added at circa 10–14 g/L of glucose units, both strains grew well and produced hydrogen with reasonable to high molar yields (2.4–3.8 moles H2/mole glucose units), and no significant production of lactate. The hydrogen production rates and yields were similar with untreated PSP, hydrolyzed PSP, and pure glucose, showing that C. saccharolyticus and T. neapolitana are well equipped for the utilization of starch. When the concentrations of the substrates were increased, growth and hydrogen production of both strains were hampered. At substrate concentrations of circa 30–40 g/L of glucose units, the molar hydrogen yield of C. saccharolyticus was severely reduced due to the formation of high amounts of lactate, while T. neapolitana was unable to grow at all. The results showed that PSP and PSP hydrolysates are very suitable substrates for efficient fermentative hydrogen production at moderate substrate loadings.
Biowaste energy potential in Kenya
Nzila, C. ; DeWulf, J. ; Spanjers, H. ; Kiriamiti, H. ; Langenhove, H. - \ 2010
Renewable Energy 35 (2010)12. - ISSN 0960-1481 - p. 2698 - 2704.
plantenresten - kenya - biogas - methaan - biobased economy - biobrandstoffen - plant residues - kenya - biogas - methane - biobased economy - biofuels - tea - waste - adsorption - digestion - zinc
Energy affects all aspects of national development. Hence the current global energy crisis demands greater attention to new initiatives on alternative energy sources that are renewable, economically feasible and sustainable. The agriculture-dependent developing countries in Africa can mitigate the energy crisis through innovative use of the available but underutilised biowaste such as organic residues from maize, barley, cotton, tea and sugarcane. Biogas technology is assumed to have the capacity to economically and sustainably convert these vast amounts of biowaste into renewable energy, thereby replacing the unsustainable fossil energy sources, and reducing dependency on fossil fuels. However, the total energy potential of biogas production from crop residues available in Kenya has never been evaluated and quantified. To this end, we selected five different types of residues (maize, barley, cotton, tea and sugarcane) from Kenya and evaluated their energy potential through biomethane potential analysis at 30 °C and a test time of 30 days. The specific methane yields for maize, barley, cotton, tea and sugarcane residues obtained under batch conditions were respectively 363, 271, 365, 67 and 177 m3 per tonne volatile solids. In terms of energy potential, maize, cotton and barley residues were found to be better substrates for methane production than tea and sugarcane residues and could be considered as potential substrates or supplements for methane production without compromising food security in the country. The evaluated residues have a combined national annual maximum potential of about 1313 million cubic meters of methane which represent about 3916 Gigawatt hour (GWh) of electricity and 5887 GWh of thermal energy. The combined electrical potential is equivalent to 73% of the country’s annual power production of 5307 GWh. Utilization of the residues that are readily available on a ‘free on site’ basis for energy production could substitute the fossil fuels that account for a third of the country’s total electricity generation. Besides, exploitation of the potential presented by the biowaste residues can spur an energy revolution in the country resulting in a major economic impact in the region.
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