Titel Deelnemers "Korte inhoud" "Assessing teachers' acceptance of educational technologies: beware for the congruency between user acceptance and actual use" "Bram Pynoo, Jo Tondeur, Wouter Duyck, Bart Sijnave, Philippe Duyck" "In this study, we investigated the extent to which self-reported measures for user acceptance (attitude, behavioral intention, self-reported frequency of use), added to the prediction of several aspects of use of a portal for education. Data from 835 teachers was collected: questionnaire U+201CacceptanceU+201D data on one occasion and five parameters for observed use (number of logins, downloads, uploads, page views, and reactions) were extracted on two occasions from the portal database. We found that the self-reported measures for acceptance primarily predicted search behavior (monthly number of logins, downloads and page views), and not share behavior (monthly number of uploads and reactions). So, researchers aiming to assess teachersU+2019 acceptance of a technology to contribute information, should adjust their measures for user acceptance so that these correspond with the targeted actual behavior." "Tracking the fate of artificial sweeteners within the coastal waters of Shenzhen city, China: from wastewater treatment plants to sea" "Wei Guo, Jun Li, Qingwei Liu, Jianghong Shi, Yue Gao" "Artificial sweeteners (ASs), as a new emerging pollutant, the fate from wastewater treatment plants (WWTPs) to sea is growing concerned. In this study, the distribution and polluted loading of six typical ASs were analyzed based on the measurement in influent, primary effluent, secondary effluent, tertiary effluent, suspended particulate matter (SPM), and sludge from four WWTPs and receiving waters near the coast of Shenzhen city, China. Elevated levels of ASs were detected in WWTPs located near a highly populated area (about 14,000 people km-2). Sucralose was predominant in all water samples (0.1-22.2 μg L-1), and had a 1.6-704.0 times higher concentration than the means of other ASs detected. Aspartame were mainly distributed in SPM and sludge, and the fractions in offshore water exceeded 45%. Acesulfame, sucralose, cyclamate and saccharin could be effectively removed by secondary biochemical treatment. The average daily loading (4.2 g d-1 1000people-1) and discharge loading (0.4 g d-1 1000people-1) of sucralose in WWTPs was higher than those of the other ASs. Dissolved organic carbon and UV254 can affect the fate of ASs, and SPM mainly affects the distributions of aspartame and neotame. As a potential sewage indicator, neotame deserves further attention." "Effect of intense rainfall events on metallic and particulate pollutant fluxes in a small urban watercourse" "Dragana Petrovic, Aurelie Magnier, M. Verbanck" "Effect of an intense storm event resulting in a combined sewer overflow (CSO) on metallic and particulate pollutant fluxes in a small urban watercourse (Zenne River crossing Brussels, Belgium) is presented. The origin and contribution of the different fractions of water to the total discharge at the monitoring station downstream of the city is reconstructed. The variations of the concentration of various metals during the survey (in the dissolved and particulate phases) are presented and show that the CSO to the Zenne, although resulting in a very intense increase of metal concentrations in river waters, has a similar effect as it would be expected from a natural resuspension process of river basin sediments." "Test_14032022_Dioxin levels in fertilizers from Belgium: Determination and evaluation of the potential impact on soil contamination" "L Pussemier, Pierre Dumortier, Georges Scholl, Leo Goeyens, Jean François Focant" "Dioxins are harmful persistent organic pollutants (POPs) to which humans are exposed mostly via the consumption of animal products. They can enter the food chain at any stage, including crop fertilization. Fertilizers belong to several categories: synthetic chemicals providing the essential elements (mostly N, P and K) that are required by the crops but also organic fertilizers or amendments, liming materials, etc. Ninety-seven samples of fertilizers were taken in Belgium during the year 2011 and analyzed after a soft extraction procedure for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DL-PCBs) using GC-IDHRMS. Only small qualitative differences could be observed between the main fertilizer categories since the PCDD:PCDF:DL-PCB average ratio obtained with the results expressed in TEQ was often close to 30:30:40 (typically for sewage sludge) or 40:30:30 (typically for compost). The median dioxin levels determined were generally lower than recorded previously and were the highest for sewage sludge and compost (5.6 and 5.5 ng TEQ/kg dry weight (dw), respectively). The levels in other fertilizers were lower including manure for which the median value was only 0.2 ng TEQ/kg dw. Several fertilization scenarios relying on the use of those fertilizers were assessed taking into consideration the application conditions prevailing in Belgium. From this assessment it could be concluded that the contribution of fertilizers to the overall soil contamination will be low by comparison of other sources of contamination such as atmospheric depositions. At the field scale, intensive use of compost and sewage sludge will increase dramatically the dioxin inputs compared with other fertilization practices but this kind of emission to the soil will still be relatively low compared to the dioxin atmospheric depositions" "Trace metals in the giant tiger prawn Penaeus monodon and mangrove sediments of the Tanzania coast" "Cyrus Charles Rumisha, Robinson H Mdegela, Marc Kochzius, Martine Leermakers, Marc Elskens" "Mangroves ecosystems support livelihood and economic activities of coastal communities in the tropics and subtropics. Previous reports have documented the inefficiency of waste treatment facilities in Tanzania to contain trace metals. Therefore, the rapidly expanding coastal population and industrial sector is likely to threaten mangrove ecosystems with metal pollution. This study analysed trace metals in 60 sediment samples and 160 giant tiger prawns from the Tanzanian coast in order to document the distribution of trace metals and to establish if measured levels present a threat to mangrove fauna and are of public health importance. High levels of Cr, Co, Cu, Fe, Mn, Ni, and V was observed in mangroves of river Pangani, Wami, and Rufiji. Multivariate analysis showed that they originate mainly from weathering and erosion in the river catchments. Extreme enrichment of Cd was observed in a mangrove affected by municipal sewage. The distribution of Hg, Pb, and Zn was related with urbanisation and industrial activities along the coast. The metal pollution index was high at Pangani, Saadani, and Rufiji, suggesting that these estuarine mangroves are also affected by human activities in the catchment. Moderate to considerable ecological risks were observed in all sampled mangroves, except for Kilwa Masoko. It was revealed that As, Cd, and Hg present moderate risks to fauna. High levels of Cu, Fe and Zn were observed in prawns but the level of the non-essential Cd, Hg, and Pb did not exceed the maximum allowed levels for human consumption. However, based on the trends of fish consumption in the country, weekly intake of Hg is likely to exceed provisional tolerable weekly intake level, especially in fishing communities. This calls for measures to control Hg emissions and to strengthen sewage and waste treatment in coastal cities and urban centres in the basin of major rivers." "Hygienisatie van organisch afval tijdens biologische verwerkingsprocessen" "Despite economic and population growth in the European Union is limited, amounts of waste are still increasing, causing unnecessary loss of materials and energy, environmental damage and negative effects on health and the quality of life. The long-term goal of the European Union is to prevent waste and to promote re-use, recycling and recovery among which biological treatment of waste (such as composting and anaerobic digestion) in order to reduce the negative environmental impact of waste. The end-product of the biological treatment of waste is used on land as crop fertilizer or for the production of potting media. Consequently, it is of great importance that pathogens and weed seeds are sufficiently reduced. Although there is an extensive literature on the survival of human and animal pathogens in farm animal and human sewage wastes, less information is available on the survival of these pathogens during green waste and vegetable, fruit and garden waste composting. Moreover, limited research has been done concerning the sanitation capacity of pre- and post-treatment processes of anaerobic digestion. Therefore, the objectives of this study were (i) recording the minimal requirements that are necessary for the inactivation of Salmonella Senftenberg W775 during green waste and vfg-waste composting and (ii) providing policy supporting advice concerning the biosafety of anaerobic digestion and the pre- and post-treatment processes. To determine the hygienic safety of composting processes, the indicator organism Salmonella enterica ssp. enterica serotype Senftenberg strain W775 was artificially inoculated on a meat carrier and monitored subsequently. Different types of composting processes, i.e. composting in enclosed facilities, in open-air and in-vessel composting, were investigated. The waste materials used in this work were either vegetable, fruit and garden wastes or green wastes. The impact of temperature, moisture content and the presence of an indigenous microflora on the eradication of W775 was determined. The temperature was found to be the most important parameter to eradicate W775 from compost. When the temperature of the compost heap was 60°C and the moisture content varied between 6065%, W775 (108 cfu g-1) was below the detection limit within 10 hours of composting. The moisture content was, beside temperature, a second parameter that influenced the survival of W775. When the water content of the composting materials or meat carriers was reduced, a higher survival rate of W775 was observed (survival rate increased 0.5 log10 unit when there was a reduction of 5% in moisture content (from 65.8 to 60.6%)). In addition, other parameters (such as microbial antagonism, toxic compounds, etc.) had an influence on the survival of W775 as well. All types of tested composting processes were sufficient to eradicate W775 providing that they are well managed in terms of temperature and moisture content. To elucidate the influence of temperature, moisture content and microbial competition on the inactivation of Salmonella Senftenberg W775, several lab-scale experiments were set up, since parameters can be controlled in a better way in these circumstances. Pieces of meat inoculated with Salmonella Senftenberg W775 were exposed to different temperatures and moisture contents. To determine the influence of indigenous microflora on the survival of Salmonella Senftenberg W775, autoclaved as well as nonautoclaved W775-infested meat samples were used. Longer survival times were observed at lower temperatures and at lower moisture contents. However, the latter seemed to be temperature-dependent, as the effect of a low moisture content changed from being sensitive to protective at a temperature between 45 and 55°C. Besides temperature and moisture content, other parameters, like microbial competition, seemed to influence the survival of Salmonella Senftenberg W775 in samples containing meat. The time-temperature relationship of different pathogens and seeds was investigated during mesophilic anaerobic digestion in lab experiments. The percentage of viable tomato seeds was below 2% (guide value according to the Ordinance on Biowastes, BioAbfV, 1998) after 2 weeks of mesophilic digestion at 36°C, while for Salmonella Senftenberg W775 a 5 log10 reduction could be reached after 7 days in the same circumstances. On the contrary, the most heat sensitive pathogen that was tested during mesophilic digestion at 36°C, i.e. Ralstonia solanacearum, was completely eliminated within 5 hours. Moreover, the hygienisation capacity of different post-treatment processes was determined at lab- as well as full-scale. A pasteurization step of 1 hour at 70°C seemed to be very efficient in the inactivation of pathogens and seeds. Both, Salmonella Senftenberg W775 and tomato seeds were already completely inactivated within 5 minutes at a temperature of 70°C. In addition, the biothermal drying process seemed to be an efficient way to inactivate Salmonella Senftenberg W775 and tomato seeds. The conveyer drying process on the contrary, was - despite the high air temperatures - not efficient in the elimination of Salmonella Senftenberg W775 or tomato seeds, as no influence could be observed in a full-scale experiment. Furthermore, it was demonstrated that the required reductions of Salmonella Senftenberg W775, Enterococcus faecalis and bovine parvovirus can be reached within the minimal guaranteed retention time during thermophilic digestion, indicating the possible use of thermophilic anaerobic digestion as an alternative process for the mandatory pasteurization step in recycling category 3 material and manure. Moreover, the minimal guaranteed retention time can be easily determined with the aid of a chemical tracer and it seemed that the tracer bromide was the most appropriate in this kind of research. The results of these experiments can only be extrapolated to other installations if they operate at least within the same temperature regime, nevertheless when bovine parvovirus is concerned extra attentiveness is recommended. On the other hand, the minimal guaranteed retention time has to be determined for each digestion installation individually. The tool BioSafety@Digestion was developed which can be used to check whether pathogens and weed seeds are eliminated in a sufficient way. For this purpose, certain conditions have to be fulfilled. On the one hand, based on the operation temperature and the minimal retention time of a certain process, it can be verified if certain pathogens and weed seeds will be inactivated. On the other hand, when a waste stream contains certain pathogens, one can determine with the aid of this tool which rise in temperature and/or prolongation of the retention time is necessary to obtain a safe end-product. In conclusion, this thesis demonstrated the hygienisation capacity of composting processes providing that they are well managed in terms of temperature and moisture content. Especially at low temperatures, the impact of moisture content and indigenous microflora enlarges. Also anaerobic digestion and post-treatment processes provide a sufficient pathogen reduction when the hydraulic retention time is long enough. Nevertheless, attention must be paid to dry heating processes because low water activity increases the heat resistance of micro-organisms." "Building water and chemicals budgets over as complex hydrographic network" "Vincent Carbonnel, Marc Elskens, M. Verbanck" "The Brussels Metropolitan Community (BMC) is a densely populated, trans-regional area of about 800 km² and 2,000,000 inhabitants, over which Brussels economy and urbanization will thrive and expand in the coming decades. The interconnected system composed of the Zenne River and the Charleroi-Brussels-Scheldt canal, which supports the complex hydrographic network in the BMC, constitutes the backbone for the sustainable development of the economy in this area.Profoundly modified over the last two centuries to address several issues such as flooding and water pollution, this hydrographic network constitutes a paradigm of a complex system submitted to multiple types of human perturbations impacting the hydrologic functioning, the watercourse, the water budget, and the water quality. In addition, as it spans over the three Belgian regions (Flanders, Brussels and Wallonia), the management of this system is divided in sections which are under the supervision of different organisms and administrations.Our general objective was to study the propagation of the anthropogenic disturbances in this aquatic system that goes through of such a densely populated and economically active area, with multiple connections and sources of pollutants. We thus established a box-model representation of water budgets and estimated polluting chemicals fluxes for the whole BMC area. As identifying and quantifying every individual chemical is a tremendous and costly task, this aim was achieved by combining classical and innovative hydrological and sediment dynamics analyses with the use of selected chemical tracers representing different types of human activities: agriculture, industries and urban surface runoff and sewage." "A biological and nitrate isotopic assessment framework to understand eutrophication in aquatic ecosystems" "David Soto Arrojo" "Eutrophication is a globally significant challenge facing aquatic ecosystems, mostly associated with human induced enrichment of these ecosystems with nitrogen and phosphorus. Given the complexity of assigning eutrophication issues to local primary N sources in field-based studies, this paper proposes a multi-stable isotope and biological framework to track nitrogen biogeochemical transformations, inputs and fate of nitrate in groundwater-dependent shallow lakes. Three representative freshwater ecosystems from the Pampa Plain (Argentina), with different land uses and topographic features were selected. Groundwater (N = 24), lake (N = 29) and stream (N = 20) samples were collected for isotope (δ15N-NO3- and δ18O-NO3-, δ18O-H2O) and hydrogeochemical (major ions and nutrients) determinations, and in the case of surface water, also for biological determinations (chlorophyll-a, fecal coliforms and nitrifying bacteria abundance). Both chemical and isotopic characteristics clearly indicated that denitrification was limited in lakes and streams, while evidence of assimilation in shallow lakes was confirmed. The results suggested that groundwater denitrification plays a role in the nitrate concentration pattern observed in the Pampeano Aquifer. The proportional contribution of nitrate sources to the inflow streams for all years were estimated by using Bayesian isotope mixing models, being ammonium nitrified in the system from soil and fertilizers ~50 - 75 %, sewage/manure ~20 - 40 % and atmospheric deposition ~5 - 15 %. In this sense, agricultural practices seem to have a relevant role in the eutrophication and water quality deterioration for these watersheds. However, limnological, bacterial and algal variables, assessed simultaneously with isotopic tracers, indicated spatio-temporal differences within and between these aquatic ecosystems. In the case of Nahuel Rucá Lake, animal manure was a significant source of nitrogen pollution, in contrast to La Brava Lake. In Los Padres Lake, agricultural practices were considered the main sources of nitrate input to the ecosystem." "Estrogenic Activity Measurements in Water Using Diffusive Gradients in Thin-Film Coupled with an Estrogen Bioassay" "Wei Guo, Kersten Van Langenhove, Michael S. Denison, Willy Baeyens, Marc Elskens, Yue Gao" "A novel type of diffusive gradients in thin-film (DGT) was combined with a chemically activated luciferase gene expression bioassay (CALUX) to measure estrogens in aquatic systems. The performance of this novel method was assessed with 17β-estradiol (E2) as the model steroid hormone, XAD 18 resin gel as the binding phase in the DGT method and VM7Luc4E2 cells (formerly BG1Luc4E2) for the Estrogen Responsive Element (ERE)-CALUX bioassay. The measured effective diffusion coefficient of E2 in agarose diffusive gel was 4.65 ± 0.37 × 10 -6 cm 2 s -1 at 25 °C. The detection limit of this combined DGT/ERE-CALUX method for 1 day of sampling (0.026 ± 0.003 ng L -1 of E2) is significantly lower than that obtained by spot sampling combined with GC-MS/MS or LC-MS/MS analysis (0.1-7.0 ng L -1). The method is independent of pH (5-8), ionic strength (0.001-0.5 M), and dissolved organic matter (DOM; concentrations up to 30 mg L -1). Field applications of this novel DGT in effluents of three sewage treatment plants in Beijing city (China) showed comparable results to conventional spot (grab) sampling. This study demonstrates that the combined DGT/ERE-CALUX approach is an effective and sensitive tool for in situ monitoring of estrogenic activity in waters and wastewaters." "Bioaccumulation and public health implications of trace metals in edible tissues of the crustaceans Scylla serrata and Penaeus monodon from the Tanzanian coast." "Cyrus Charles Rumisha, Martine Leermakers, Robinson H Mdegela, Marc Kochzius, Marc Elskens" "The coastal population in East Africa is grow- ing rapidly but sewage treatment and recycling facilities in major cities and towns are poorly developed. Since estuarine mangroves are the main hotspots for pollut- ants, there is a potential for contaminants to accumulate in edible fauna and threaten public health. This study analysed trace metals in muscle tissues of the giant mud crabs (Scylla serrata) and the giant tiger prawns (Penaeus monodon) from the Tanzanian coast, in order to determine the extent of bioaccumulation and public health risks. A total of 180 samples of muscle tissues of S. serrata and 80 of P. monodon were collected from nine sites along the coast. Both species showed high levels of trace metals in the wet season and significant bioaccumulation of As, Cu and Zn. Due to their burrowing and feeding habits, mud crabs were more contaminated compared to tiger prawns sampled from the same sites. Apart from that, the measured levels of Cd, Cr and Pb did not exceed maximum limits for human consumption. Based on the current trend of fish consumption in Tanzania (7.7 kg/person/year), the mea- sured elements (As, Cd, Co, Cu, Mn, Pb and Zn) are not likely to present health risks to shellfish consumers. Nevertheless, potential risks of As and Cu cannot be ruled out if the average per capita consumption is exceeded. This calls for strengthened waste manage- ment systems and pollution control measures."