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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    Towards spatially smart abatement of human pharmaceuticals in surface waters: defining impact of sewage treatment plants on susceptible functions
    Gils, J.A.G. ; Coppens, L.J.C. ; Laak, T.L. ter; Raterman, B.W. ; Wezel, A.P. van - \ 2015
    Water Research 81 (2015). - ISSN 0043-1354 - p. 356 - 365.
    afvalwaterbehandeling - waterzuivering - geneesmiddelen - oppervlaktewater - inventarisaties - nederland - waste water treatment - water treatment - drugs - surface water - inventories - netherlands - personal care products - endocrine disrupting compounds - organic persistent pollutants - health-risk assessment - municipal waste-water - aquatic environment - drinking-water - climate-change - transformation products - continental-scale
    For human pharmaceuticals, sewage treatment plants (STPs) are a major point of entry to surface waters. The receiving waters provide vital functions. Modeling the impact of STPs on susceptible functions of the surface water system allows for a spatially smart implementation of abatement options at, or in the service area of, STPs. This study was performed on a nation-wide scale for the Netherlands. Point source emissions included were 345 Dutch STPs and nine rivers from neighboring countries. The Dutch surface waters were represented by 2511 surface water units. Modeling was performed for two extreme discharge conditions. Monitoring data of 7 locations along the rivers Rhine and Meuse fall mostly within the range of modeled concentrations. Half of the abstracted volumes of raw water for drinking water production, and a quarter of the Natura 2000 areas (European Union nature protection areas) hosted by the surface waters, are influenced by STPs at low discharge. The vast majority of the total impact of all Dutch STPs during both discharge conditions can be attributed to only 19% of the STPs with regard to the drinking water function, and to 39% of the STPs with regard to the Natura 2000 function. Attributing water treatment technologies to STPs as one of the possible measures to improve water quality and protect susceptible functions can be done in a spatially smart and cost-effective way, using consumption-based detailed hydrological and water quality modeling.
    Comparative study of nitrate leaching models on a regional scale
    Roelsma, J. ; Hendriks, R.F.A. - \ 2014
    Science of the Total Environment 499 (2014). - ISSN 0048-9697 - p. 481 - 496.
    agricultural land-use - soil-crop model - groundwater nitrate - sandy soils - drinking-water - system stone - netherlands - nitrogen - losses - simulation
    In Europe and North America the application of high levels of manure and fertilisers on agricultural land has led to high levels of nitrate concentrations in groundwater, in particular on sandy soils. For the evaluation of the development of the quality of groundwater a sound quantitative basis is needed. In this paper a comparison has been made between observations of nitrate concentrations in the upper groundwater and predictions of nitrate leaching models. Observations of nitrate concentrations in the upper groundwater at three different locations in regions with mainly sandy soils in the eastern and northern part of the Netherlands were used to test the performance of the simulation models to predict nitrate leaching to the upper groundwater. Four different types of simulation models of different levels of complexity and input data requirement were tested. These models are ANIMO (dynamic complex process oriented model), MM-WSV (meta-model), WOG (simple process oriented model) and NURP (semi-empiric model). The performance of the different simulation models was evaluated using statistical criteria. The dynamic complex process oriented ANIMO model showed the best model performance. The MM-WSV meta-model was the second best model, whilst the simple process oriented WOG model produced the worst model performance. The best model performance showed the dynamic complex process oriented ANIMO model in predicting the nitrate concentrations in the upper groundwater of the Klooster catchment. The good performance of the ANIMO model for this catchment can be explained by the additional information about the use of manure and fertilisers at farm level in this study area. The ANIMO model may be a good tool to predict nitrate concentrations in the upper groundwater on a regional scale. However, the use of a detailed process oriented simulation model requires a comprehensive set of input data. If such a comprehensive data-set is not available the MM-WSV model (meta-model) proves to be a good alternative. The WOG and NURP models are suitable for long term (>8 years) predictions of average nitrate concentrations in the upper groundwater on a regional scale. (C) 2014 Elsevier B.V. All rights reserved.
    Formation of genotoxic compounds by medium pressure ultra violet treatment of nitrate rich water
    Martijn, A.J. ; Boersma, M.G. ; Vervoort, Jacques ; Rietjens, I. ; Kruithof, J.C. - \ 2014
    Desalination and Water Treatment 52 (2014)34-36. - ISSN 1944-3994 - p. 6275 - 6281.
    aqueous-solution - photochemical-reaction - drinking-water - nitrite - excitation - biphenyl - nitrogen - ions - uv
    Genotoxic compounds were produced by full-scale medium pressure (MP) ultraviolet hydrogen peroxide (UV/H2O2) treatment of nitrate-rich pretreated surface water. It was hypothesized that this formation was caused by the reaction of nitrate photolysis intermediates with natural organic matter (NOM). An increase in the Ames test response was also found after MP UV photolysis of water containing Pony Lake NOM from the International Humic Substances Society (IHSS) and nitrate, while no increase in the Ames test response was found when nitrate was absent. The same trend in an Ames test response and nitrite formation was observed for both nitrate-rich pretreated surface water and reconstituted water containing NOM and nitrate. Therefore, the conversion of nitrate by MP UV photolysis was studied in several water types. In organic-free water, nitrate was completely converted into nitrite, while no inorganic nitrogen was lost. Also in nitrate-rich surface water, nitrite was found as the only inorganic reaction product, while a small decrease of the inorganic nitrogen content was observed. When NOM was replaced by phenol, MP UV photolysis caused a restricted nitrite formation only, together with a large loss of inorganic nitrogen. The formation of the nitrated phenol derivatives, 2- and 4-nitrophenol and 4-nitrocatechol, was observed with highest concentrations under practical UV conditions. It is hypothesized that the formation of nitrated aromatic compounds is the cause of the increased Ames test response by MP UV treatment.
    Different compositions of pharmaceuticals in Dutch and Belgian rivers explained by consumption patterns and treatment efficiency
    Laak, T.L. ter; Kooij, P.J.F. ; Tolkamp, H. ; Hofman, J. - \ 2014
    Environmental Science and Pollution Research 21 (2014)22. - ISSN 0944-1344 - p. 12843 - 12855.
    waste-water treatment - personal care products - treatment plants - environmental concentrations - transformation products - aquatic environment - risk-assessment - drinking-water - removal - fate
    In the current study, 43 pharmaceuticals and 18 transformation products were studied in the river Meuse at the Belgian-Dutch border and four tributaries of the river Meuse in the southern part of the Netherlands. The tributaries originate from Belgian, Dutch and mixed Dutch and Belgian catchments. In total, 23 pharmaceuticals and 13 transformation products were observed in samples of river water collected from these rivers. Observed summed concentrations of pharmaceuticals and transformation products in river water ranged from 3.5 to 37.8 µg/L. Metformin and its transformation product guanylurea contributed with 53 to 80 % to this concentration, illustrating its importance on a mass basis. Data on the flow rate of different rivers and demographics of the catchments enabled us to calculate daily per capita loads of pharmaceuticals and transformation products. These loads were linked to sales data of pharmaceuticals in the catchment. Simple mass balance modelling accounting for human excretion and removal by sewage treatment plants revealed that sales could predict actual loads within a factor of 3 for most pharmaceuticals. Rivers that originated from Belgian and mixed Dutch and Belgian catchments revealed significantly higher per capita loads of pharmaceuticals (16.0¿±¿2.3 and 15.7¿±¿2.1 mg/inhabitant/day, respectively) than the Dutch catchment (8.7¿±¿1.8 mg/inhabitant/day). Furthermore, the guanylurea/metformin ratio was significantly lower in waters originating from Belgium (and France) than in those from the Netherlands, illustrating that sewage treatment in the Belgian catchment is less efficient in transforming metformin into guanylurea. In summary, the current study shows that consumption-based modelling is suitable to predict environmental loads and concentrations. Furthermore, different consumption patterns and wastewater treatment efficiency are clearly reflected in the occurrence and loads of pharmaceuticals in regional rivers.
    Synergistic and species-specific effects of climate change and water colour on cyanobacterial toxicity and bloom formation
    Ekvall, M.K. ; Faassen, E.J. ; Gustafsson, J.A. ; Lurling, M. ; Hansson, L. - \ 2013
    Freshwater Biology 58 (2013)11. - ISSN 0046-5070 - p. 2414 - 2422.
    dissolved organic-carbon - harmful cyanobacteria - subg. dolichospermum - drinking-water - genus anabaena - lakes - daphnia - toxins - biomanipulation - microcystins
    Cyanobacterial blooms are a worldwide phenomenon in both marine and freshwater ecosystems and are predicted to occur more frequently due to global climate change. However, our future water resources may also simultaneously suffer from other environmental threats such as elevated amounts of humic content and consequent increased water colour, a phenomenon called 'brownification'. In order to investigate the effects of temperature and water colour in combination, we performed a mesocosm experiment combining a 3 °C increase in temperature and a doubling in water colour. With this, we created a projected future scenario for our water resources, and we specifically focused on how these changes would affect cyanobacterial bloom formation and toxicity. We showed that despite total cyanobacterial biomass remaining unaffected, the abundance of one individual cyanobacterial species, Microcystis botrys, increased in response to the combination of elevated temperature and increased water colour. Furthermore, population fluctuations in M. botrys explained the majority of the variations in microcystin concentrations, suggesting that this species was responsible for the more than 300% higher microcystin concentrations in the future scenario treatment compared to the ambient scenario. Hence, it was not a change in cyanobacterial biomass, but rather a species-specific response that had the most profound impact on bloom toxicity. We argue that understanding such species-specific responses to multiple stressors is crucial for proper management decisions because toxic blooms can significantly affect both biodiversity and ecosystem functioning, as well as ecosystem services such as drinking water supply and recreation. © 2013 John Wiley & Sons Ltd.
    Recovery of avirulent, thermostable Newcastle disease virus strain NDV4-C from cloned cDNA and stable expression of an inserted foreign gene
    Zhang, X. ; Liu, H. ; Liu, P. ; Peeters, B.P.H. ; Zhao, C. ; Kong, X. - \ 2013
    Archives of Virology 158 (2013)10. - ISSN 0304-8608 - p. 2115 - 2120.
    vaccine candidate - drinking-water - fusion protein - ebola-virus - v4 strain - virulence - replication - sequence - rescue - dna
    A reverse genetics system for thermostable Newcastle disease virus (NDV) is not currently available. In this study, we developed a reverse genetics system for the avirulent and thermostable NDV4-C strain. Successful recovery of NDV4-C was achieved by using either T7 RNA polymerase or cellular RNA polymerase II to drive transcription of the full-length virus antigenome from cloned cDNA. The recovered viruses rNDV4-C (T7) and rNDV4-C (CMV) showed similar growth properties, thermostability, and virulence as the parental strain NDV4-C. The potential of rNDV4-C (T7) to serve as a viral vector was assessed by generating a recombinant virus, rNDV4-eGFP, which expressed enhanced green fluorescent protein. The rNDV4-eGFP could stably carry and express eGFP for at least fifteen passages. The reverse genetics system for NDV4-C will make it possible to analyze the genetic elements that determine thermostability and the oncolytic properties of NDV.
    Potential of mechanical cleaning of membranes from a mebrane bioreactor
    Brink, P. van den; Vergeldt, F.J. ; As, H. van; Zwijnenburg, A. ; Temmink, H. - \ 2013
    Journal of Membrane Science 429 (2013). - ISSN 0376-7388 - p. 259 - 267.
    drinking-water - biofilm reactor - critical flux - waste-water - exopolysaccharides - denitrification - precipitation - communities - limitation - bacteria
    Several membrane fouling mechanisms have been identified in membrane bioreactors. While cake layers can be removed by physical cleaning, irreversible fouling such as a gel layer is difficult to remove by physical cleaning during filtration. Harsh mechanical cleaning was applied in this study to evaluate how much fouling could be maximally removed and distribution of remaining fouling was investigated. The fouling resistance of several membranes operated at different relatively low fluxes was followed during long term continuous flux operation. Remaining fouling was observed with scanning electron microscopy (SEM) and magnetic resonance imaging (MRI). Dead-end filtration tests with mechanically cleaned membranes showed a decreased permeability. To determine whether bacteria were present in the remaining fouling, oxygen consumption was quantified. Even after harsh mechanical cleaning, membrane samples showed considerable oxygen consumption. SEM did not show fouling inside the membrane. Of several membranes operated for at least 1 year, the permeate side was covered with bacteria and extracellular polymeric substances (EPS). These results show that fouling cannot be removed completely by harsh mechanical cleaning and that both feed and permeate side of the membrane contains biofouling. This fouling on the permeate side should not be neglected when designing membrane cleaning.
    Interaction effects between sender and receiver processes in indirect transmission of Campylobacter jejuni between broilers.
    Bunnik, B.A.D. van; Hagenaars, T.H.J. ; Bolder, N.M. ; Nodelijk, G. ; Jong, M.C.M. de - \ 2012
    BMC Veterinary Research 8 (2012). - ISSN 1746-6148
    swine-fever virus - drinking-water - netherlands - epidemic - quantification - salmonella - resistance - bacteria - evaluate - design
    Background: Infectious diseases in plants, animals and humans are often transmitted indirectly between hosts (or between groups of hosts), i.e. via some route through the environment instead of via direct contacts between these hosts. Here we study indirect transmission experimentally, using transmission of Campylobacter jejuni (C. jejuni) between spatially separated broilers as a model system. We distinguish three stages in the process of indirect transmission; (1) an infectious "sender" excretes the agent, after which (2) the agent is transported via some route to a susceptible "receiver", and subsequently (3) the receiver becomes colonised by the agent. The role of the sender and receiver side (stage 1 and stage 3) was studied here by using acidification of the drinking water as a modulation mechanism. Results: In the experiment one control group and three treatment groups were monitored for the presence of C. jejuni by taking daily cloacal swabs. The three treatments consisted of acidification of the drinking water of the inoculated animals (the senders), acidification of the drinking water of the susceptible animals (the receivers) or acidification of the drinking water of both inoculated and susceptible animals. In the control group 12 animals got colonised out of a possible 40, in each treatment groups 3 animals out of a possible 40 were found colonised with C. jejuni. Conclusions: The results of the experiments show a significant decrease in transmission rate (beta) between the control groups and treatment groups (p <0.01 for all groups) but not between different treatments; there is a significant negative interaction effect when both the sender and the receiver group receive acidified drinking water (p = 0.01). This negative interaction effect could be due to selection of bacteria already at the sender side thereby diminishing the effect of acidification at the receiver side.
    Fluid intake and the risk of urothelial cell carcinomas in the European Prospective Investigation into Cancer and Nutrition (EPIC)
    Ros, M.M. ; Bueno de Mesquita, H.B. ; Büchner, F.L. ; Kampman, E. ; Duijnhoven, F.J.B. van - \ 2011
    International Journal of Cancer 128 (2011)11. - ISSN 0020-7136 - p. 2695 - 2708.
    food frequency questionnaire - disinfection by-products - lower urinary-tract - bladder-cancer - drinking-water - relative validity - life-style - consumption - epidemiology - coffee
    Results from previous studies investigating the association between fluid intake and urothelial cell carcinomas (UCC) are inconsistent. We evaluated this association among 233,236 subjects in the European Prospective Investigation into Cancer and Nutrition (EPIC), who had adequate baseline information on water and total fluid intake. During a mean follow-up of 9.3 years, 513 first primary UCC occurred. At recruitment, habitual fluid intake was assessed by a food frequency questionnaire. Multivariable hazard ratios were estimated using Cox regression stratified by age, sex and center and adjusted for energy intake, smoking status, duration of smoking and lifetime intensity of smoking. When using the lowest tertile of intake as reference, total fluid intake was not associated with risk of all UCC (HR 1.12; 95%CI 0.86–1.45, p-trend = 0.42) or with risk of prognostically high-risk UCC (HR 1.28; 95%CI 0.85–1.93, p-trend = 0.27) or prognostically low-risk UCC (HR 0.93; 95%CI 0.65–1.33, p-trend = 0.74). No associations were observed between risk of UCC and intake of water, coffee, tea and herbal tea and milk and other dairy beverages. For prognostically low-risk UCC suggestions of an inverse association with alcoholic beverages and of a positive association with soft drinks were seen. Increased risks were found for all UCC and prognostically low-risk UCC with higher intake of fruit and vegetable juices. In conclusion, total usual fluid intake is not associated with UCC risk in EPIC. The relationships observed for some fluids may be due to chance, but further investigation of the role of all types of fluid is warranted.
    Validation of the REA bioassay to detect estrogenic activity in the water cycle
    Nguyen, M.T. ; Oost, R. van der; Bovee, T.F.H. - \ 2011
    Toxicology in Vitro 25 (2011)8. - ISSN 0887-2333 - p. 2003 - 2009.
    endocrine-disrupting compounds - green fluorescent protein - mass-spectrometry - liquid-chromatography - treatment plants - drinking-water - waste-water - fish
    Endocrine disrupting compounds (EDCs) with estrogenic potency contaminate water and might eventually cause adverse effects to the aquatic environment. Many estrogenic compounds are not completely removed by wastewater treatment systems and, together with the run-off from agricultural areas, they enter surface waters. Chemical analytical methods to determine these compounds are usually expensive and laborious. Therefore, screening bioassays which are able to detect compounds based on their effects offer a solution for prior selection of samples that need to be chemically analyzed. In this study, the REA (RIKILT yeast Estrogen bioAssay), which has been developed to detect estrogenic compounds in calf urine and animal feed at RIKILT, is validated at the Water Board Laboratory of Waterproef for water samples. According to EC Decision 2002/657, detection capability CCß, specificity and stability have to be determined for the internal validation of a qualitative screening test. In addition, surface water and effluent samples were analyzed to further demonstrate the applicability of the validated test procedure. Results demonstrate that the REA assay is reproducible and specific for estrogenic compounds in water and meets the criteria as prescribed in EC Decision 2002/657. The assay was sensitive enough to detect estrogenic activity of pollutants in water with a limit of quantification (LOQ) below 1 ng EEQ/L. This means that samples can be compared with preliminary threshold levels for drinking water and surface waters (7 and 1 ng EEQ/L, respectively). The stability of estrogenic activity in water samples is at least 4 weeks, when stored at 4 °C. --------------------------------------------------------------------------------
    Anaerobic effluent disinfection using ozone: Byproducts formation
    Silva, G.H.R. ; Daniel, L.A. ; Bruning, H. ; Rulkens, W.H. - \ 2010
    Bioresource Technology 101 (2010)18. - ISSN 0960-8524 - p. 6981 - 6986.
    municipal waste-water - drinking-water - ozonation - aldehyde - acid - uv
    This research was aimed at studying oxidation processes, coliform inactivation effectiveness and disinfection byproducts (DBPs) associated with the disinfection of anaerobic sanitary wastewater effluent with ozone applied at doses of 5.0, 8.0 and 10.0mg O(3)L(-1) for contact times of 5, 10 and 15 min. The wastewater used in this research was generated by the wastewater treatment plant (WWTP), University of São Paulo - Brazil. The total coliform inactivation range was 2.00-4.06 log(10), and the inactivation range for Escherichia coli was 2.41-4.65 log(10). Mean chemical oxygen demand (COD) reductions were 37.6%, 48.8% and 42.4% for doses of 5.0, 8.0 and 10.0mg O(3)L(-1), respectively. Aldehyde formation varied with dosage only when the ozone dose was increased from 5.0 to 8.0mg O(3)L(-1) for acetaldehyde and from 5.0 to 8.0 and from 8.0 to 10.0mg O(3)L(-1) for glyoxal
    The nutritional requirements of infants. Towards EU alignment of reference values: the EURRECA network
    Hermoso, M. ; Tabacchi, G. ; Iglesia-Altaba, I. ; Bel-Serrat, S. ; Moreno-Aznar, L.A. ; Garcia-Santos, Y. ; Rosario Garcia-Luzardo, M. Del; Santana-Salguero, B. ; Pena-Quintana, L. ; Serra-Majem, L. ; Hall Moran, V. ; Dykes, F. ; Decsi, T. ; Benetou, V. ; Plada, M. ; Trichopoulou, A. ; Raats, M.M. ; Doets, E.L. ; Berti, C. ; Cetin, I. ; Koletzko, B. - \ 2010
    Maternal and Child Nutrition 6 (2010)2. - ISSN 1740-8695 - p. 55 - 83.
    breast-fed infants - nutrient intake values - vitamin-d deficiency - espghan committee - human-milk - complementary foods - randomized intervention - cobalamin status - iron-deficiency - drinking-water
    This paper presents a review of the current knowledge regarding the macro- and micronutrient requirements of infants and discusses issues related to these requirements during the first year of life. The paper also reviews the current reference values used in European countries and the methodological approaches used to derive them by a sample of seven European and international authoritative committees from which background scientific reports are available. Throughout the paper, the main issues contributing to disparities in micronutrient reference values for infants are highlighted. The identification of these issues in relation to the specific physiological aspects of infants is important for informing future initiatives aimed at providing standardized approaches to overcome variability of micronutrient reference values across Europe for this age group.
    Utilization of oligo- and polysaccharides at microgram-per-litre levels in freshwater by Flavobacterium johnsoniae
    Sack, E.L.W. ; Wielen, P.W.J.J. van der; Kooij, D. van der - \ 2010
    Journal of Applied Microbiology 108 (2010)4. - ISSN 1364-5072 - p. 1430 - 1440.
    assimilable organic-carbon - drinking-water - extracellular polysaccharides - biofilm formation - potable water - phytoplankton - matter - bacteria - enumeration - dynamics
    Aims: To obtain a bacterial strain that can be used to quantify biodegradable polysaccharides at concentrations of a few micrograms per litre in freshwater. Methods and Results: Flavobacterium johnsoniae strain A3 was isolated from tap water supplemented with laminarin, pectin or amylopectin at 100 µg C l-1 and river Rhine water. The organism utilized 14 of 23 oligo- and polysaccharides, and 1 of 9 monosaccharides, but none of the sugar acids, sugar alcohols, carboxylic acids or aromatic acids tested at 10 µg C l-1. Amino acids promoted growth of strain A3, but not in coculture with assimilable organic carbon (AOC) test strain Pseudomonas fluorescens P17, which utilized these compounds more rapidly than strain A3. Compounds released by strain P17 and AOC test strain Spirillum sp. NOX grown on acetate promoted the growth of strain A3 at Nmax values of = 2 × 105 CFU ml-1 of strain P17 and = 5 × 105 CFU ml-1 of strain NOX. Significant growth of strain A3 was observed in surface water and in tap water in the presence of strain P17 (Nmax P17 <2 × 105 CFU ml-1). Conclusions: Strain A3 utilizes oligo- and polysaccharides at microgram-per-litre levels. In surface water and in tap water, the organism was able to utilize compounds that were not utilized by strain P17. These compounds may include oligo- and/or polysaccharides. Significance and Impact of the Study: Phytoplanktonic and bacterial polysaccharides can constitute an important biodegradable fraction of natural organic matter in water and may promote growth of heterotrophic bacteria during water treatment and drinking water distribution. Strain A3 can be used to quantify a group of compounds that includes oligo- and polysaccharides at microgram-per-litre levels in freshwater
    Polaromonas and Hydrogenophaga species are the predominant bacteria cultured from granular activated carbon filters in water treatment
    Magic-Knezev, A. ; Wullings, B.A. ; Kooij, D. van der - \ 2009
    Journal of Applied Microbiology 107 (2009)5. - ISSN 1364-5072 - p. 1457 - 1467.
    tert-butyl ether - 16s ribosomal-rna - assimilable organic-carbon - drinking-water - distribution-system - beta-proteobacterium - tap water - gen-nov - biofilms - bacterioplankton
    AIM: Identification of the predominating cultivable bacteria in granular activated carbon (GAC) filters used in a variety of water treatment plants for selecting representative strains to study the role of bacteria in the removal of dissolved organic matter. METHODS AND RESULTS: Bacterial isolates were collected from 21 GAC filters in nine water treatment plants treating either ground water or surface water with or without oxidative pretreatment. Enrichment of samples in dilute liquid medium improved culturability of the bacteria by approximately log unit, to 9% up to 70% of the total cell counts. Genomic fingerprinting and 16S rDNA sequence analysis revealed that most (68%) of the isolates belonged to the Betaproteobacteria and 25% were identified as Alphaproteobacteria. The number of different genera within the Betaproteobacteria was higher in the GAC filters treating ozonated water than in the filters treating nonozonated water. Polaromonas was observed in nearly all of the GAC filters (86%), and the genera Hydrogenophaga, Sphingomonas and Afipia were observed in 43%, 33% and 29% of the filter beds, respectively. AFLP analysis revealed that the predominating genus Polaromonas included a total of 23 different genotypes. CONCLUSIONS: This study is the first to demonstrate that Polaromonas, which has mainly been observed in ultraoligotrophic freshwater environments, is a common component of the microbial community in GAC filters used in water treatment. SIGNIFICANCE AND IMPACT OF THE STUDY: The predominance of ultraoligotrophic bacteria in the GAC filters indicates that very low concentrations of substrates are available for microbial growth. Polaromonas species are suited for further studies on the nutritional versatility and growth kinetics enabling the modelling of biodegradation processes in GAC filters
    Percolation and Survival of Escherichia coli O157:H7 and Salmonella enterica Serovar Typhimurium in Soil Amended with Contaminated Dairy Manure or Slurry
    Semenov, A.V. ; Overbeek, L.S. van; Bruggen, A.H.C. van - \ 2009
    Applied and Environmental Microbiology 75 (2009)10. - ISSN 0099-2240 - p. 3206 - 3215.
    pseudomonas-fluorescens - cow manure - aggregative behavior - o157-h7 survival - irrigation water - drinking-water - bovine manure - fresh produce - fate - transport
    The effect of cattle manure and slurry application on percolation and survival of Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium was investigated for different soil depths after the addition of water. Four treatments were chosen for the first set of experiments: (i) addition of inoculated farmyard manure on the soil surface, (ii) mixing of inoculated farmyard manure with the top 10 cm of soil, (iii) addition of inoculated slurry on the soil surface, and (iv) injection of inoculated slurry into the top 10 cm of the soil. Homogeneity of water distribution in the soil profile was confirmed by a nondestructive nuclear magnetic resonance method. Survival data were fitted to a modified logistic model, and estimated survival times were compared. In the second set of experiments, pathogen-inoculated farmyard manure or slurry was applied to soil columns with 1-month-old lettuce plants. More pathogen cells percolated to greater depths after slurry than after manure application. Survival of E. coli O157:H7 was significantly longer in soil with slurry than in that with manure, while survival of Salmonella serovar Typhimurium was equally high with manure and slurry. The densities of the pathogens were not different in the rhizosphere compared to the bulk soil with manure, while the densities were higher by 0.88 ± 0.11 and 0.71 ± 0.23 log CFU per g (dry weight), respectively, in the rhizosphere than in bulk soil after slurry application. Our results suggest that surface application of manure may decrease the risk of contamination of groundwater and lettuce roots compared to injection of slurry.
    Changing climate-changing pathogens: Toxoplasma gondii in North-Western Europe
    Meerburg, B.G. ; Kijlstra, A. - \ 2009
    Parasitology Research 105 (2009)1. - ISSN 0932-0113 - p. 17 - 24.
    united-states - experimental transmission - congenital toxoplasmosis - production systems - transport hosts - drinking-water - costa-rica - infection - cats - oocysts
    In this review, we describe the effects of global climate change for one specific pathogen: the parasite Toxoplasma gondii. It is postulated that an increase of T. gondii prevalence in humans can occur in some regions of North-Western Europe as a result of changing environmental conditions. Such a change can be predicted by using Global Climate Change models. We have elaborated such a prediction for one scenario (SRES A1) by using one specific model (CCSR/NRIES) as an example. Next to environmental factors, also anthropogenic factors may contribute to increased prevalence of T. gondii in this region. In order to counter the potential severe consequences of a potential increase resulting from the combination of climatic and anthropogenic factors, there is an urgent need for the development of a human vaccine. Until a vaccine that offers complete protection is developed, the emphasis should be on treatment optimization and prevention.
    Optimisation and significance of ATP analysis for measuring active biomass in granular activated carbon filters used in water treatment
    Magic-Knezev, A. ; Kooij, D. van der - \ 2004
    Water Research 38 (2004)18. - ISSN 0043-1354 - p. 3971 - 3979.
    waterzuivering - drinkwater - actieve kool - atp - biologische filtratie - biofilms - microbiële activiteiten - water treatment - drinking water - activated carbon - atp - biological filtration - biofilms - microbial activities - drinking-water - microbial activity - microscopy - bacteria - plant
    A method for determining the concentration of active microbial biomass in granular activated carbon (GAC) filters used in water treatment was developed to facilitate studies on the interactions between adsorption processes and biological activity in such filters. High-energy sonication at a power input of 40 W was applied to GAC samples for the detachment of biomass which was measured as adenosine triphosphate (ATP)
    A method for determining the concentration of active microbial biomass in granular activated carbon (GAC) filters used in water treatment was developed to facilitate studies on the interactions between adsorption processes and biological activity in such filters. High-energy sonication at a power input of 40 W was applied to GAC samples for the detachment of biomass which was measured as adenosine triphosphate (ATP). Modelling of biomass removal indicated that a series of six to eight sonication treatments of 2 min each yielded more than 90% of the attached active biomass. The ATP concentrations in 30 different GAC filters at nine treatment plants in The Netherlands ranged from 25 to 5000 ng ATP cm(-3) GAC, with the highest concentrations at long filter run times and pretreatment with ozone. A similar concentration range was observed in nine rapid sand (RS) filters. ATP concentrations correlated significantly (p <0.05) with total direct bacterial cell counts in each of these filter types, but the median value of the ATP content per cell in GAC filters (2.1 x 10(-8) ng ATP/cell) was much lower than in the RS filters (3.6 x 10(-7) ng ATP/cell). Average biofilm concentrations ranging from 500 to 10(5) pg ATP cm(-2) were calculated assuming spherical shapes for the GAC particles but values were about 20 times lower when the surface of pores > I mum diameter is included in these calculations. The quantitative biomass analysis with ATP enables direct comparisons with biofilm concentrations reported for spiral wound membranes used in water treatment, for distribution system pipes and other aquatic environments. (C) 2004 Elsevier Ltd. All rights reserved.
    Effect of synthetic iron colloids on the microbiological NH4+ removal process during groundwater purification
    Wolthoorn, A. ; Temminghoff, E.J.M. ; Riemsdijk, W.H. van - \ 2004
    Water Research 38 (2004)7. - ISSN 0043-1354 - p. 1884 - 1892.
    ammonium - ijzer - grondwater - waterzuivering - verwijdering - drinkwater - beluchting - colloïden - grondwaterwinning - ammonium - iron - groundwater - water treatment - removal - drinking water - aeration - colloids - groundwater extraction - transient-behavior - drinking-water - transport - nitrification - phosphate - column - mobilization - nitrosomonas - adsorption - sediments
    Subsurface aeration is used to oxidise Fe in situ in groundwater that is used to make drinking water potable. In a groundwater system with pH>7 subsurface aeration results in non-mobile Fe precipitate and mobile Fe colloids. Since originally the goal of subsurface aeration is to remove iron in situ, the formation of non-mobile iron precipitate, which facilitates the metal's removal, is the desired result. In addition to this intended effect, subsurface aeration may also strongly enhance the microbiological removal of ammonium (NH4+) in the purification station. Mobile iron colloids could be the link between subsurface aeration and the positive effect on the NH4+ removal process. Therefore, the objective of this study was to assess whether synthetic iron colloids could improve the NH4+ removal process. The effect of synthetic iron colloids on the NH4+ removal process was studied using an artificial purification set-up on a laboratory scale
    Subsurface aeration is used to oxidise Fe in situ in groundwater that is used to make drinking water potable. In a groundwater system with pH > 7 subsurface aeration results in non-mobile Fe precipitate and mobile Fe colloids. Since originally the goal of subsurface aeration is to remove iron in situ, the formation of non-mobile iron precipitate, which facilitates the metal's removal, is the desired result. In addition to this intended effect, subsurface aeration may also strongly enhance the microbiological removal of ammonium (NH4+) in the purification station. Mobile iron colloids 4 could be the link between subsurface aeration and the positive effect on the NH4+ removal process. Therefore, the objective of this study was to assess whether synthetic iron colloids could improve the NH4+ removal process. The effect of synthetic iron colloids on the NH4+ removal process was studied using an artificial purification set-up on a laboratory scale. Columns that purified groundwater with or without added synthetic iron colloids were set up in duplicate. The results showed that the NH4+ removal was significantly (alpha = 0.05) increased in columns treated with the synthetic iron colloids. Cumulative after 4 months about 10% more NH4+ was nitrified in the columns that was treated with the groundwater containing synthetic iron colloids. The results support the hypothesis that mobile iron colloids could be the link between subsurface aeration and the positive effect on the NH4+ removal process. (C) 2004 Elsevier Ltd. All rights reserved.
    Survival and resuscitation of ten strains of Campylobacter jejuni and Campylobacter coli under acid conditions
    Chaveerach, P. ; Huurne, A.A.H.M. ter; Lipman, L.J.A. ; Knapen, F. van - \ 2003
    Applied and Environmental Microbiology 69 (2003)1. - ISSN 0099-2240 - p. 711 - 714.
    non-culturable campylobacter - broiler-chickens - drinking-water - cells - recovery - colonization - salmonella - forms - contamination - maintenance
    The culturability of 10 strains of Campylobacter jejuni and Campylobacter coli was studied after the bacteria were exposed to acid conditions for various periods of time. Campylobacter cells could not survive 2 h under acid conditions (formic acid at pH 4). The 10 Campylobacter strains could not be recovered, even when enrichment media were used. Viable cells, however, could be detected by a double-staining (5-cyano-2,3-ditolyl tetrazolium chloride [CTC]-4',6'-diamidino-2-phenylindole [DAPI]) technique, demonstrating that the treated bacteria changed into a viable but nonculturable (VBNC) form; the number of VBNC forms decreased over time. Moreover, some VBNC forms of Campylobacter could be successfully resuscitated in specific-free-pathogen fertilized eggs via two routes, amniotic and yolk sac injecting.
    Acrylamide exposure from foods of the Dutch population and an assessment of the consequent risks
    Konings, E.J.M. ; Baars, A.J. ; Klaveren, J.D. van; Spanjer, M.C. ; Rensen, P.M. ; Hiemstra, M. ; Kooij, J.A. van; Peters, P.W.J. - \ 2003
    Food and Chemical Toxicology 41 (2003)11. - ISSN 0278-6915 - p. 1569 - 1579.
    maillard reaction - chronic toxicity - drinking-water - rats - oncogenicity - performance
    At the end of April 2002, the Swedish Food Administration reported the presence of acrylamide in heat treated food products. Acrylamide has been shown to be toxic and carcinogenic in animals, and has been classified by the WHO/IARC among others as `probably carcinogenic for humans¿. The purposes of this study were firstly to analyse acrylamide contents of the most important foods contributing to such exposure, secondly, to estimate the acrylamide exposure in a representative sample of the Dutch population, and thirdly to estimate the public health risks of this consumption. We analysed the acrylamide content of foods with an LC¿MS¿MS method. The results were then used to estimate the acrylamide exposure of consumers who participated in the National Food Consumption Survey (NFCS) in 1998 (n=6250). The exposure was estimated using the probabilistic approach for the total Dutch population and several age groups. For 344 food products, acrylamide amounts ranged from
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