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Emerging organic contaminants have not received a lot of attention in developing countries, particularly Africa, although problems regarding water quantity and quality are often even more severe than in more developed regions. This study presents general water quality parameters as well as unique data on concentrations and loads of 24 pharmaceuticals including antibiotic, anti(retro)viral, analgesic, anti-inflammatory and psychiatric drugs in three wastewater treatment plants, three rivers and three groundwater wells in Nairobi and Kisumu. This allowed studying removal efficiencies in wastewater treatment, identifying important sources of pharmaceutical pollution and distinguishing dilution effects from natural attenuation in rivers. In general, antiretrovirals and antibiotics, being important in the treatment of common African diseases such as HIV and malaria, were in all matrices more prevalent as compared to the Western world. Wastewater stabilization ponds removed pharmaceuticals with an efficiency between 11 and 99%. Despite this large range, a different removal is observed for a number of compounds, as compared to more conventional activated sludge systems. Total concentrations in river water (up to 320 μg L(-1)) were similar or exceeded concentrations in untreated wastewater, with domestic discharges from slums, wastewater treatment plant effluent and waste dumpsites identified as important sources. In shallow wells situated next to pit latrines and used for drinking water, the recalcitrant antiretroviral nevirapine was measured at concentrations as high as 1-2 μg L(-1). Overall, distinct pharmaceutical contamination patterns as compared to the Western world can be concluded, which might be a trigger for further research in developing regions.

The objective of this study was to investigate the effect of two pen cleaning techniques for pig fattening houses on the indoor concentrations of particulate matter (PM 1 , PM 2.5 and PM 10 ), ammonia (NH 3 ) and greenhouse gases (CO 2 , CH 4 , N 2 O), using a multi-pollutant approach. Both cleaning techniques were tested in a conventional housing system and in a low-ammonia-emission housing system. In total, four compartments from the conventional housing system and four from the low-ammonia-emission housing system were sampled during two consecutive fattening periods between August 2011 and June 2012. Two compartments from each housing system were only cleaned dry, while the other two received a more intensive cleaning. Indoor concentrations of NH 3 , CO 2 , CH 4 , N 2 O and PM were measured continuously. Overall, the low-ammonia-emission housing system showed no reduction in indoor pollutant concentrations compared to the conventional system, except for CH 4 . The additional wet cleaning and disinfection step in the more intensive cleaning protocol did not result in consistently lower indoor concentrations for the studied pollutants.

It is well known that vertical canopy gradients and varying sky conditions influence photosynthesis (Pn), specific leaf area (SLA), leaf thickness (LT) and leaf pigments (lutein, â-carotene and chlorophyll). In contrast, little is known about these effects on monoterpenoid (MT) emissions. Our study examines simultaneously measured Pn, MT emissions and the MT/Pn ratio along the canopy of an adult European beech tree (Fagus sylvatica L.) in natural forest conditions. Dynamic branch enclosure systems were used at four heights in the canopy (7, 14, 21 and 25 m) in order to establish relationships and better understand the interaction between Pn and MT emissions under both sunny and cloudy sky conditions. Clear differences in Pn, MT emissions and the MT/Pn ratio were detected within the canopy. The highest Pn rates were observed in the sun leaves at 25 m due to the higher intercepted light levels, whereas MT emissions (and the MT/Pn ratio) were unexpectedly highest in the semi-shaded leaves at 21 m. The higher Pn rates and, apparently contradictory, lower MT emissions in the sun leaves may be explained by the hypothesis of Owen and Penuelas (2005), stating synthesis of more photo-protective carotenoids may decrease the emissions of volatile isoprenoids (including MTs) because they both share the same biochemical precursors. In addition, leaf traits like SLA, LT and leaf pigments clearly differed with height in the canopy, suggesting that the leaf's physiological status cannot be neglected in future research on biogenic volatile organic compounds (BVOCs) when aiming at developing new and/or improved emission algorithms.

The aim of this paper was to evaluate the performance of biotrickling filters (BTFs) for treating low concentrations of dimethyl disulfide (DMDS), using different bacterial consortia adapted to consume reduced sulfur compounds under alkaline (pH ≈ 10) or neutral (pH ≈ 7) conditions. Solubility experiments indicated that the partition of DMDS in neutral and alkaline mineral media was similar to the value with distilled water. Respirometric assays showed that oxygen consumption was around ten times faster in the neutrophilic as compared with the alkaliphilic consortium. Batch experiments demonstrated that sulfate was the main product of the DMDS degradation. Two laboratory-scale BTFs were implemented for the continuous treatment of DMDS in both neutral and alkaline conditions. Elimination capacities of up to 17 and 24 gDMDS m−3 h−1 were achieved for the alkaliphilic and neutrophilic reactors with 100% removal efficiency after an initial adaptation and biomass build-up.

A practical and efficient treatment of PCBs (polychlorinated biphenyls) in transformer oil by a chemical dechlorination process has been reported. The transformer oil containing commercial PCB mixtures Sovtol-10 was treated by the required amounts of PEG 400 (polyethylene glycol 400) and powdered potassium hydroxide (KOH), along with different reaction times. The reaction of PEG with PCBs under basic condition produces arylpolyglycols and potassium chlorine. The relative efficiencies of PCB treatment process were assessed in terms of destruction and removal efficiency (DRE, %). Under the experimental conditions of KOH/PEG molar ratio 1.2:1, KPEG/oil 22:1 and three hours of reaction at 90 °C, average DRE of PCBs was approximately 99%, showing completely removal of PCBs containing 5-7 chlorines. In the sample remain the congeners 52 and 44 that are not reported as toxic by the WHO (World Health Organization). With the previously reported conditions the scale up of the process was realized.

Passive sampling of volatile organic compounds (VOCs) in air has received increasing attention in recent years. However, in order to use passive sampling as a reliable sampling technique a compound and sampler specific uptake rate is needed. Therefore, the scope of our study was threefold. First, uptake rates for 25 VOCs were determined under real indoor and outdoor conditions using axial-sampling tube-type samplers filled with Tenax TA, and active (pumped) sampling as a reference technique. Secondly, the mechanisms of passive sampling were investigated by comparing the experimentally determined uptake rates (0.13–0.46 ml min−1) to the ideal uptake rates, calculated based on Fick’s first law of diffusion and sampler geometry. Sampling efficiency SE, defined as the ratio between the experimental and ideal uptake rate, was introduced as a correction factor and showed that ideal uptake rates may underestimate VOC concentrations by a factor up to 4. This compound dependent SE is explained in terms of the partitioning coefficient K, i.e. the compound’s Tenax TA to air concentration equilibrium ratio. Compounds with a low K-value showed the most pronounced non-ideal sorptive behavior. Third, the experimentally determined uptake rates were used to determine VOC concentrations (between 12 and 311 μg m−3) in 6 homes for the elderly in Antwerp (Belgium). This study provides unique data for indoor air quality at care centers in Flanders.

Direct plant stress sensing is the key for a quantitative understanding of drought stress effects on biogenic volatile organic compound (BVOC) emissions. A given level of drought stress might have a fundamentally different effect on the BVOC emissions of different plants. For the first time, we continuously quantified the level of drought stress in a young potted beech (Fagus sylvatica L.) with a linear variable displacement transducer (LVDT) installed at stem level in combination with simultaneous measurements of BVOC emissions and photosynthesis rates at leaf level. This continuous set of measurements allowed us to examine how beech alters its pattern of photosynthesis and carbon allocation to BVOC emissions (mainly monoterpenes, MTs) and radial stem growth during the development of drought stress. We observed an increasing-decreasing trend in the MT emissions as well as in the fraction of assimilated carbon re-emitted back into the atmosphere (ranging between 0.14 and 0.01%). We were able to link these dynamics to pronounced changes in radial stem growth, which served as a direct plant stress indicator. Interestingly, we detected a sudden burst in emission of a non-identified, non-MT BVOC species when drought stress was acute (i.e. pronounced negative stem growth). This burst might have been caused by a certain stress-related green leaf volatile, which disappeared immediately upon re-watering and thus the alleviation of drought stress. These results highlight that direct plant stress sensing creates opportunities to understand the overall complexity of stress-related BVOC emissions.

A dynamic branch enclosure system was used to measure emission rates of biogenic volatile organic compounds (BVOCs) from two common European tree species: Fraxinus excelsior and Quercus robur under ambient conditions in Flanders (Belgium). Both tree species were studied for seasonal variability of BVOC emission rates under natural biotic stress (infestations). Emissions were normalized at standard conditions of temperature and photosynthetic active radiation (PAR) (30°C and 1000 µmol m−2 s−1, respectively). Emission rates from Fraxinus excelsior were highest in May (9.56 µg gDW −1 h−1) and lowest in October (1.17 µg gDW −1 h−1). This tree species emitted (Z)-β-ocimene, (E)-β-ocimene and α-farnesene during the entire measurement period and additionally isoprene only in May. Quercus robur showed isoprene emission variations according to the seasonal cycle with rates of 30, 106 and 29 µg gDW −1 h−1 in May, August and October, respectively. Apart from isoprene, (E)-β-ocimene and β-caryophyllene were emitted t...

Induced volatiles have been a focus of recent research, as not much is known of their emission behavior or atmospheric contribution. BVOC emissions were measured from Pseudotsuga menziesii saplings under natural environmental conditions, using a dynamic branch enclosure system and GC–MS for their analysis. We determined temperature and light dependency of the individual compounds, studied seasonality of the emissions and discuss the effect of heat stress in comparison with two specific biotic stresses that occurred naturally on the trees. A standardized emission rate of 6.8 μg g(dw)−1 h−1 for monoterpenes under stressed conditions was almost a magnitude higher than that obtained for healthy trees (0.8 ± 0.2 μg g(dw)−1 h−1), with higher beta factors characterizing the stressed trees. The response of the emissions to light intensity was different for the individual compounds, suggesting a distinct minimum light intensity to reach saturation. Heat stress changed the relative contribution of specific volatiles, with larger extent of increase of sesquiterpenes, methyl salicylate and linalool emissions compared to monoterpenes. Biotic stress kept low the emissions of sesquiterpenes, (E)-4,8-dimethyl-1,3,7-nonatriene and methylbutenol isomers, and increased the level of methyl salicylate and monoterpenes. The ratio of β-pinene/α-pinene was also found to be significantly enhanced from 1.3 to 2.4 and 3.2 for non-stressed, heat stressed and combined biotic and heat stressed, respectively.

In the past decade, we have witnessed rapid development of direct-injection mass spectrometric (DIMS) technologies that combine ever-improving mass and time resolution with high sensitivity and robustness. Here, we review some of the most significant DIMS technologies, which have been applied to rapid monitoring and quantification of volatile organic compounds (VOCs) and biogenic VOCS (BVOCs). They include MS-e-noses, atmospheric-pressure chemical ionization (APCI), proton-transfer-reaction mass spectrometry (PTR-MS), and selected ion-flow-tube mass spectrometry (SIFT-MS). DIMS-based MS-e-noses provide the possibility to screen large sample sets and may yield rich analytical information. APCI is a widespread ionization method and pioneered DIMS in environmental and flavor-release applications. SIFT-MS and PTR-MS allow better control of precursor-ion generation and hence of the ionization process. SIFT-MS puts the focus on control of the ionization process, while PTR-MS does so on sensitivity. Most (B)VOCs of interest can be efficiently detected and often identified by DIMS, thanks also to the possibility of switching between different precursor ions and the recent realization of time-of-flight-based equipments. Finally, we give selected examples of applications for each of the key technologies, including research in food-quality control (MS-e-nose), flavor release (APCI), environmental sciences (PTR-MS) and health sciences (SIFT-MS).

We measured the isoprene and monoterpene fluxes continuously above a mixed forest site at Vielsalm in the eastern part of Belgium, using the disjunct eddy covariance technique with proton transfer reaction-mass spectrometry. Simultaneously, we also measured the carbon dioxide fluxes in order to deduce the gross primary production. The measurements were conducted from July to September 2009. During the day, the seasonal evolution of the isoprene/monoterpene emissions was studied using a monthly temperature and light dependence function deduced from our results to standardize the fluxes. A seasonal decrease in the standard emission factors was observed, probably linked to acclimation or senescence. The standard emission factor for isoprene fluxes (30 °C, 1000 μmol m −2 s −1 ) fell from 0.91 ± 0.01 to 0.56 ± 0.02 μg m −2 s −1 and for monoterpene fluxes from 0.74 ± 0.03 to 0.27 ± 0.03 μg m −2 s −1 . During the night, a slight positive flux of monoterpenes was observed that seemed to be driven by air temperature. The standard emission factor (30°C) for nighttime monoterpene fluxes was equal to 0.093 ± 0.019 μg m −2 s −1 . Finally, we studied the seasonal evolution of the relationship between the gross primary production and the isoprene/monoterpenes fluxes. A linear relationship was observed, highlighting the strong link between carbon assimilation and isoprene/monoterpene emissions.

Although biogenic volatile organic compounds (BVOCs) only represent a very limited fraction of the plant’s carbon (C) budget, they play an important role in atmospheric chemistry for example as a precursor of tropospheric ozone. We performed a study comparing BVOC emissions of European beech (Fagus sylvatica L.) in controlled and natural environmental conditions. A young and adult beech tree was exposed to short-term temperature variations in growth room conditions and in an experimental forest, respectively. This study attempts to clarify how short-term temperature variations between days influenced the ratio between monoterpenoid (MT) emissions and net photosynthesis (Pn). Within a temperature range of 17–27 °C and 13–23 °C, the MT/Pn carbon ratio increased 10–30 fold for the growth room and forest, respectively. An exponential increasing trend between MT/Pn C ratio and air temperature was observed in both conditions. Beech trees re-emitted a low fraction of the assimilated C back into the atmosphere as MT: 0.01–0.12% and 0.01–0.30% with a temperature rise from 17 to 27 °C and 13–23 °C in growth room and forest conditions, respectively. However, the data showed that the MT/Pn C ratio of young and adult beech trees responded significantly to changes in temperature.

Monoterpenoid emissions from Fagus sylvatica L. trees have been measured at light- and temperature-controlled conditions in a growth chamber, using Proton Transfer Reaction Mass Spectrometry (PTR-MS) and the dynamic branch enclosure technique. De novo synthesized monoterpenoid Standard Emission Factors, obtained by applying the G97 algorithm ( Guenther, 1997 ), varied between 2 and 32 μg gDW−1 h−1 and showed a strong decline in late August and September, probably due to senescence. The response of monoterpenoid emissions to temperature variations at a constant daily light pattern could be well reproduced with a modified version of the MEGAN algorithm ( Guenther et al., 2006 ), with a typical dependence on the average temperature over the past five days. The diurnal emissions at constant temperature showed a typical hysteretic behaviour, which could also be adequately described with the modified MEGAN algorithm by taking into account a dependence on the average light levels experienced by the trees during the past 10–13 h. The impact of the past light and temperature conditions on the monoterpenoid emissions from F. sylvatica L. was found to be much stronger than assumed in previous algorithms. Since our experiments were conducted under low light intensity, future studies should aim at confirming and completing the proposed algorithm updates in sunny conditions and natural environments.

In this paper, two methods for measuring the equilibrium vapor sorption in polymers are critically compared and data on sorption of toluene, p-xylene, hexane, cyclohexane, and heptane in low density polyethylene are reported. The vapor phase calibration method (VPC) was used to measure vapor sorption at low vapor activities in air (below 0.01), and the gravimetric method was used to measure sorption over wide range of activities of pure vapors (0.1–0.9). The Flory-Huggins interaction parameter (in amorphous phase) varied between 1.00 for cyclohexane and 1.19 for toluene. The resulting confidence intervals are conjunctive, indicating that both methods provide consistent results.

The interest in quantitative analysis of biogenic volatile organic compounds (BVOCs) emissions stems from their importance in atmospheric chemistry. In order to compare the most frequently used BVOC measurement techniques, simultaneous on-line PTR-MS and off-line GC-MS data collection was performed on a 3 years old Fagus sylvatica L. tree placed in a growth chamber. Using an internal standard (deuterated toluene) and applying the selective ion mode (SIM) resulted in significant improvements of monoterpene (MT) quantification by TD-GC-MS. PTR-MS quantification of MTs was based on the ion signal at m/z 137. In the course of the experiments the relative contribution of linalool compared to that of MTs was found to be up to 84%. Since this compound has also a PTR-MS signature at m/z 137, quantification of MT emission rates by PTR-MS was disturbed. Comparison of GC-MS and PTR-MS data allowed an estimation of the ratio of the PTR-MS sensitivity for linalool to the one for MTs at m/z 137. This ratio of sensitivities, combined with the information of the relative contribution of linalool to the sum of linalool and MTs obtained by GC-MS, resulted in accurate derivation of the sum of emission rates of linalool and MTs by PTR-MS. The results indicate that fast and on-line PTR-MS measurements of BVOCs are best accompanied by off-line GC measurements to detect possible interferences or to use the additional information for properly quantifying the sum of emission rates of several compounds.

The effect of the ratio of the electric field to the buffer gas number density ( E / N ) in the drift tube reactor of a proton transfer reaction-mass spectrometer (PTR-MS) on the product ion distributions of seven common biogenic unsaturated alcohols (2-methyl-3-buten-2-ol, 1-penten-3-ol, cis-3-hexen-1-ol, trans-2-hexen-1-ol, 1-octen-3-ol, 6-methyl-5-hepten-2-ol and linalool) has been investigated. At low E / N values, the dominant product ion is the dehydrated protonated alcohol. Increasing E / N results in more extensive fragmentation for all compounds. For cis-3-hexenol and 6-methyl-5-hepten-2-ol the contribution of the protonated molecule can be enhanced by reducing E / N with respect to commonly used PTR-MS E / N values (120–130 Td). Significant differences have been found between some of the isomeric species studied, opening a way for selective detection. The C 10 alcohol linalool mainly results in product ions at m / z 137 and 81, which are also PTR-MS fingerprints of monoterpenes. This may complicate monoterpene quantification when linalool and monoterpenes are simultaneously present in sampled air. Furthermore the influence of the water vapour pressure in the PTR-MS inlet line on the product ion distributions has been determined. Some major fingerprint ions of the unsaturated alcohols were found to depend significantly on the water vapour pressure in the inlet line and this should be taken into account for accurate quantification of these species by PTR-MS.

Volatile organic compounds (VOCs) have been the focus of interest to understand atmospheric processes and their consequences in formation of ozone or aerosol particles; therefore, VOCs contribute to climate change. In this study, biogenic VOCs (BVOCs) emitted from Fagus sylvatica L. trees were measured in a dynamic enclosure system. In total 18 compounds were identified: 11 monoterpenes (MT), an oxygenated MT, a homoterpene (C14H18), 3 sesquiterpenes (SQT), isoprene and methyl salicylate. The frequency distribution of the compounds was tested to determine a relation with the presence of the aphid Phyllaphis fagi L. It was found that linalool, (E)-β-ocimene, α-farnesene and a homoterpene identified as (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), were present in significantly more samples when infection was present on the trees. The observed emission spectrum from F. sylvatica L. shifted from MT to linalool, α-farnesene, (E)-β-ocimene and DMNT due to the aphid infection. Sabinene was quantitatively the most prevalent compound in both, non-infected and infected samples. In the presence of aphids α-farnesene and linalool became the second and third most important BVOC emitted. According to our investigation, the emission fingerprint is expected to be more complex than commonly presumed.

In this work, fractions that are the result of the demolition phase of a dwelling house have been investigated with respect to their recovery potential: stony material, wood, metals, glass, synthetic materials and a rest fraction. Depending on their nature, different alternative end-of-life scenarios have been investigated to replace disposal, such as re-use, recycling or incineration with heat and electricity production. All resources necessary for these scenarios have been inventoried. At the same time, those that are not longer necessary for the disposal and those that would have been necessary to make the obtained products from virgin resources are quantified. Based on these three items, the overall balance results into the calculation of net virgin resource savings for different end-of-life scenarios, quantified in Cumulative Exergy Consumption (MJ of exergy). For this specific case, the best end-of-life scenario can save virgin natural resources with a content of 258 GJ of exergy. Looking at the entire life cycle of the house, i.e. construction phase, use phase and end-of-life phase, the quantitative analysis shows a saving of virgin natural resources of 15% with the implementation of the best end-of-life scenario instead of disposal as end-of-life.

Resource management becomes a key issue in the development of sustainable technology. This paper envisages a quantification of all energy and material needs for a family dwelling, both for the construction aspects (‘embodied energy and materials’) and usage aspects. To do so, an exergetic life-cycle assessment has been carried out that enables the quantification of all necessary natural energy and material resources simultaneously. The case study covered 65 optimized Belgian family dwelling types with low energy input (56 MJ/(m 3 year)). The study shows that cumulative annual exergy demand is of the order of 65 GJ exergy /year, with a limited dependency on the construction type: cavity wall, external insulation or wooden frame. For the cavity wall and external insulation building type, non-renewable inputs are dominant for the construction with 85–86% of the total exergy to be extracted out of the environment. For the wooden frame, non-renewable resource intake for construction remains 62%. Despite the low-energy building type, heating requirements during the use phase are dominant in the overall resource intake with a 60% of the total annual exergy consumption. In order to make family dwellings less fossil resource dependant, the study learns that particularly reduction of heating requirements should be envisaged.

The effects of the ratio of the electric field strength to the buffer gas number density ( E / N ) in the drift tubeof a proton transfer reaction mass spectrometer on the product ion distributions of the sesquiterpenes -caryophyllene, -humulene, -cedreneandlongifolenehavebeeninvestigated.Chemicalionizationofthesesquiterpenes resulted in important fragmentation of the nascent excited ion/molecule complex at thehighest E / N values. The most important fragment ions were common to all sesquiterpenes and thereforecannot be used as fingerprints for specific isomers. The yield of the protonated molecule increased onaverage by a factor 1.6 by decreasing E / N from 140 to 80 Td. Taking into account the influence of E / N onthe reaction time and on the reactant ion mobility, it is estimated that this decrease in E / N may lead toan overall increase in the PTR-MS detection sensitivity of sesquiterpenes (based on the ion signal at m / z 205) by a factor 3.5.Product ion distributions of -cedrene and longifolene have also been determined atdifferent water vapour pressures. No substantial influence of the water vapour pressure on the production yields was observed, which is an advantage when quantifying sesquiterpenes by PTR-MS in samplesof varying relative humidity.© 2008 Elsevier B.V. All rights reserved.

The objective of the paper is to establish a comprehensive resource-based life cycle impact assessment (LCIA) method which is scientifically sound and that enables to assess all kinds of resources that are deprived from the natural ecosystem, all quantified on one single scale, free of weighting factors. The method is based on the exergy concept. Consistent exergy data on fossils, nuclear and metal ores, minerals, air, water, land occupation, and renewable energy sources were elaborated, with well defined system boundaries. Based on these data, the method quantifies the exergy "taken away" from natural ecosystems, and is thus called the cumulative exergy extraction from the natural environment (CEENE). The acquired data set was coupled with a state-of-the art life cycle inventory database, ecoinvent. In this way, the method is able to quantitatively distinguish eight categories of resources withdrawn from the natural environment: renewable resources, fossil fuels, nuclear energy, metal ores, minerals, water resources, land resources, and atmospheric resources. Third, the CEENE method is illustrated for a number of products that are available in ecoinvent, and results are compared with common resource oriented LCIA methods. The application to the materials in the ecoinvent database showed that fossil resources and land use are of particular importance with regard to the total CEENE score, although the other resource categories may also be significant.

Indoor air concentrations of volatile organic compounds often exceed outdoor levels by a factor of 5. There is much interest in developing new technologies in order to improve indoor air quality. In this work non-thermal plasma (DC positive corona discharge) is explored as an innovative technology for indoor air purification. An inlet gas stream of 10 l min −1 containing 0.50 ± 0.02 ppm toluene was treated by the plasma reactor in atmospheric conditions. Toluene removal proved to be achievable with a characteristic energy density e 0 of 50 J l −1 . Removal efficiencies were higher for 26% relative humidity ( e 0 = 35 J l −1 ), compared with those at increased humidities (50% relative humidity, e 0 = 49 J l −1 ). Reaction products such as formic acid, benzaldehyde, benzyl alcohol, 3-methyl-4-nitrophenol, 4-methyl-2-nitrophenol, 4-methyl-2-propyl furan, 5-methyl-2-nitrophenol, 4-nitrophenol, 2-methyl-4,6-dinitrophenol are identified by means of mass spectrometry. Based on these by-products a toluene degradation mechanism is proposed.

Ozonation was investigated as a potential post-treatment step for biologically treated landfill leachate to enhance the biodegradability and observe the influence of the initial organic matter concentration and pH. Changes in COD, UV absorption at 254 nm (UVA254) and BOD content were measured during and after ozonation, and the ozone utilisation efficiency at different conditions was calculated. The initial COD concentration was found to influence the absolute removal of UVA254 significantly, but especially changes in pH influenced the ozone reactions. Increased pH (pH 10) most probably increased the overall hydroxyl radical production leading to a higher COD removal and a much better ozone utilisation compared to lower pH. This in contrast to initial COD variations which had little influence on the determined ozone utilisation. Regardless of initial COD content or pH, on average 10% of the initial COD content was converted to BOD, next to 10% COD that was removed.

This paper describes the volatile metabolite production of spoilage bacteria ( Pantoea agglomerans and Rahnella aquatilis ) and spoilage yeasts ( Pichia fermentans and Cryptococcus laurentii ), previously isolated from mixed lettuce, on a simulation medium of shredded mixed lettuce (mixed-lettuce agar) both under air conditions and modified atmosphere (MA)-conditions at 7 °C. These latter conditions simulated the equilibrium modified atmosphere packaging, which is used to extend the shelf-life of shredded mixed lettuce. Besides volatile metabolites, organic acid metabolites and consumption of sugars were measured. Microbiological growth on the mixed-lettuce agar resulted in metabolite production and consumption of sugars. Bacteria and yeasts produced a range of volatile organic compounds both under air conditions and MA-conditions: ethanol, ethyl acetate, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 2,3-butanedione, 3-methyl-1-pentanol, 1-butanol and 1-hexanol. Under MA-conditions, 2-methyl-1-butanol, 3-methyl-1-butanol and ethanol were the first compounds that were detected in the headspace as being produced by the inoculated micro-organisms. In the case of the yeast P. fermentans , production of these compounds was detected from a count of 5.0 ± 0.1 log cfu/cm 2 with a fast increase when exceeding 6.0–6.5 log cfu/cm 2 . Unlike P. fermentans , the yeast C. laurentii showed a slow metabolism under MA-conditions, compared to air conditions. In the case of the bacteria, production of 2-methyl-1-butanol and 3-methyl-1-butanol was detected starting from a count of 6.7 ± 0.1 log cfu/cm 2 in the case of R. aquatilis and from a count of 7.1 ± 0.4 log cfu/cm 2 in the case of P. agglomerans with a fast increase when exceeding 8 log cfu/cm 2 . No production of ethanol by the bacteria under MA-conditions was detected in contradiction to air conditions. It could be concluded that, if these counts are reached on the cut surfaces of shredded mixed lettuce which are simulated by the mixed-lettuce agar, sensorial quality of shredded mixed lettuce could be influenced by the microbiological production of metabolites.

Quality changes of strawberries during storage can be caused both by microbiological and physiological processes. There is little known about the possible contribution of microbiological processes to the quality degradation of strawberries. In this study, quality of strawberries during storage was evaluated by analytical and sensorial analyses. It was the aim to investigate the influence of microbiological activity on the changes of different quality factors of strawberries during storage. During storage at 7 degrees C, quality was mainly determined by the odor and by visual defects. Regarding the odor, highly microbiologically contaminated late-season strawberries packaged in air at 7 degrees C became sensorially unacceptable due to the presence of high amounts of ethyl acetate. This could be attributed to the yeast proliferation: at yeast concentrations above 5.0 log cfu/g, an increase in ethanol was detected in the headspace of the strawberries. It was shown that ethanol was converted to ethyl acetate by strawberries resulting in an unacceptable odor. In an experiment with low microbiologically contaminated early-season strawberries, not reaching the above mentioned yeast counts, less ethyl acetate was detected which resulted in strawberries that were sensorially acceptable during the whole storage period (12 days). Strawberries packaged in modified atmosphere conditions showed a different quality pattern due to the effect of decreased O2-concentrations on both microbiological and physiological processes. This paper demonstrates that also microbiological processes on strawberries should be considered as they could play an important role in the sensorial quality when interacting with physiological processes.

This study presents an efficiency and renewability analysis of the production of three biofuels: rapeseed methyl ester (RME), soybean methyl ester (SME) and corn-based ethanol (EtOH). The overall production chains have been taken into account: not only the agricultural crop production and the industrial conversion into biofuel, but also production of the supply of agricultural resources (pesticides, fertilizers, fuel, seeding material) and industrial resources (energy and chemicals) to transform the crops into biofuel. Simultaneously, byproducts of the agricultural and industrial processes have been taken into account when resources have to be allocated to the biofuels. The technical analysis via the second law of thermodynamics revealed that corn-based EtOH results in the highest production rate with an exergetic fuel content of 68.8 GJ ha(-1) yr(-1), whereas the RME and SME results were limited to 47.5 and 16.4 GJ ha(-1) yr(-1). The allocated nonrenewable resource input to deliver these biofuels is significant: 16.5, 15.4, and 5.6 MJ ha(-1) yr(-1). This means that these biofuels, generally considered as renewable resources, embed a nonrenewable fraction of one-quarter for EtOH and even one-third for RME and SME. This type of analysis provides scientifically sound quantitative information that is necessarywith respect to the sustainability analysis of so-called renewable energy.

In biotrickling filters, mass transfer of hydrophobic compounds is the limiting factor. Biofilters are static systems, and so control and regulation of operational parameters such as pH and nutrient supply can be a problem. In membrane bioreactors, these drawbacks can be avoided. The hydrophobic membrane separates the waste air from the aqueous phase, thus avoiding mass-transfer limitation, while pH and nutrient supply can be directly controlled. In this contribution, an overview will be given of results obtained during a four-year project. First, the physical chemical characteristics (solubility, permeability, diffusivity) and microbial adhesion of different membranes were tested. This led to the selection of a composite membrane consisting of a porous polyvinylidenefluoride (PVDF) support layer coated with a thin (1 or 2.5 μm) dense polydimethylsiloxane (PDMS) top layer. This membrane was mounted into a module provided with four parallel rectangular channels for gas flow (in contact with the porous layer) and nutrient solution (in contact with the dense layer) respectively. After inoculation, a biofilm developed on the dense layer. Experiments were performed with dimethyl sulphide and toluene as target VOCs. Operational characteristics such as elimination capacity as a function of the volumetric load and residence time, effect of nutrient supply, long-term performance) were determined. Mass transfer was studied by measuring concentration profiles along the channels of the module in different conditions.

For the purposes of a research project for the Flemish authorities, olfactometric measurements were carried out at six closed pig farms and six fattener farms. The results of these olfactometric measurements were compared with the olfactometric results of n-butanol samples and samples of a synthetic gas mixture of ethanethiol, methylacetate and 2-propanol in nitrogen, both analysed on the same days as the air samples from the pig farms. The results of the n-butanol tests for all panellists showed that nobody was qualified according to the CEN criteria, and that, consequently, these criteria are rather stringent. Comparing the variability of the results for the three different odours showed that the mean and standard deviation of the mean variance were not significantly different for the three odour types, which means that the repeatability of the panellist results was equal for the examined odour types. The principle of traceability was checked by comparing the variance of the n-butanol, pig odour and synthetic mixture ratio. For the complete dataset, the principle of traceability could not been proven for n-butanol. For the restricted dataset, the principle of traceability was more valid for n-butanol than for the mixture, but differences were small. Finally, normalization was looked for with regard to olfactometric measurements of air samples from pig farms based either on n-butanol or on the synthetic mixture. Both models had low determination coefficients, but the model based on the synthetic mixture gave better results than the one based on n-butanol.

Since the 1980s, environmental engineering education has been a rapidly growing discipline in many universities. This paper discusses the history, the current status and the near future of environmental engineering education at Ghent University. This university, with about 50% of the Flemish university environmental engineering students, can be considered as representative for the situation in Flanders, Belgium. In contrast to many other universities, environmental engineering education at Ghent University does not have its historical roots in civil engineering, but has been developed from the curricula organized by the former Faculty of Agricultural Sciences. As part of a reorganisation of the education and research activities at this faculty, a curriculum leading to the degree of “bio-engineer in environmental technology” was established in 1991. This curriculum covers a 5-year study and is constructed around 8 main components. Exchange of students with other European universities, e.g. within the Socrates framework, has become a prominent aspect of student life and education. This paper also briefly describes the employment opportunities of graduated bio-engineers in environmental technology. Finally, the current implementation of the bachelor's-master's structure, leading to a “master of science in environmental technology” degree is summarized.

Decision-makers should strive for an efficient employment of resources for the whole industrial ecological system. The metabolization of resources should be optimized in thermodynamic terms. This contribution presents an effort to use exergy analysis as a quantitative tool in the thermodynamic optimization of the life cycle of plastics. Quantitative results on overall exergetic efficiencies of different industrial metabolic options are presented. Therefore, different waste treatment options of plastics will be considered, taking into account interacting industrial activities, such as virgin plastics production and heat and electricity production starting from natural resources. Copyright © 2004 John Wiley & Sons, Ltd.

In dealing with chlorinated organic compounds in waste gases, traditional treatment techniques show some severe shortcomings. Thermal oxidation may lead to the formation of dioxins, active carbon adsorption does not degrade the pollutants and biotechnological treatment is difficult since microorganisms do not always possess efficient degradation pathways for these compounds. These drawbacks explain the growing interest of the waste gas treatment sector for Advanced Oxidation Processes (AOPs) which were initially developed as water treatment techniques. AOPs generate highly reactive hydroxyl radicals that efficiently oxidise organic pollutants. In the peroxone process, this is done by a combination of ozone and hydrogen peroxide. In this work, the peroxone process is applied in an oxidative scrubber for the removal of trichloroethylene (TCE). Rapid oxidation of absorbed TCE in the liquid phase enhances TCE absorption. Practically, a gas stream contaminated with TCE is mixed with an ozone loaded gas stream. The mixture is led through a bubble column that is fed with a buffered hydrogen peroxide solution. The effect of different process parameters (flow rates, buffer concentration, pH, hydrogen peroxide/ozone dosage ratio, TCE dosage) on TCE removal was investigated. Depending on the operating conditions, removal efficiencies up to 98% could be attained.

A DC-excited atmospheric pressure glow discharge in a multi-pin-to-plate electrode configuration is applied to the removal of trichloroethylene (TCE) in air. A removal fraction of up to 47% is obtained at an energy density of 35 J litre−1 (air flow rate: 60 m3 h−1; residence time: 50 ms; TCE inlet concentration: 120 ppm; temperature: 298 K). The addition of TCE increases the discharge impedance and improves the uniformity of the current distribution in the direction of the gas flow. In the investigated inlet concentration range (0–160 ppm), no influence of the TCE admixture is observed on the corona-to-glow and glow-to-spark threshold currents. Experiments with other volatile organic compounds (VOCs) reveal that molecules containing a double carbon bond have the lowest energy requirement for decomposition.

This study evaluated the effect of feed form and grinding intensity of the pig diet and the interaction between both on the particulate matter (PM) concentrations inside a pig nursery and the growth performances of weanling pigs. Four diets were compared: finely ground meal, coarsely ground meal, finely ground pellets, and coarsely ground pellets. Four weaning rounds with 144 pigs per weaning round, divided over 4 identical compartments, were monitored. Within each weaning round, each compartment was randomly assigned to 1 of 4 treatments. A hammer mill with a screen of 1.5 or 6 mm was used to grind the ingredients of the finely ground and coarsely ground feeds, respectively. Indoor concentrations of the following PM fractions were measured: PM that passes through a size-selective inlet with a 50 % efficiency cutoff at 10 (PM10) , 2.5 (PM2.5), or 1 (PM1) μm aerodynamic diameter, respectively (USEPA, 2004). Feeding pelleted diets instead of meal diets gave rise to higher PM10 (P0.001), PM2.5 (P0.001), and PM1 (P0.001) concentrations. Grinding intensity had an effect only on PM10 (P0.05) concentrations. No interaction between feed form and grinding intensity was found for any of the PM fractions. Interactions (P0.05) between feed form and grinding intensity on ADFI and ADG were found. Grinding intensity had an effect only on the meal diets with higher ADFI for the coarsely ground meal. Pigs fed the finely ground meal had a lower (P0.001) ADG than the other 3 diets. Feed efficiency was influenced only by the feed form (P0.001) and not by the grinding intensity. Pelleting the feed gave rise to a higher G:F. In conclusion, a contradiction between environmental concerns and performance results was found. Feeding pelleted diets to the piglets improved growth performance but also increased indoor PM concentrations.

Treatment of chlorinated organic compounds in waste gases is difficult because of several reasons: these compounds are dioxin precursors when incinerated, and also biological treatment is difficult because of a limited number of suitable microbial degradation pathways. On the other hand, since the 1990s, a new generation of chemical oxidation techniques has been introduced in water treatment. Advanced Oxidation Processes (AOPs) are based on a combination of UV/H2O2, UV/O3 or H2O2/O3. The combinations result in the generation of OH-radicals, which subsequently attack the organic pollutants. In this work, the treatment of a gas stream (240 L/h) loaded with 20-40 ppmv trichloroethylene (TCE) is presented. Therefore, a combination of an absorption process in a bubble column with a liquid H2O2/O3 initiated oxidation, was investigated. Removal efficiencies, depending on the dosed H2O2 and O3, up to 94% were found. The production of chloride ions was investigated: the Cl-atoms from the removed TCE could be found back as chloride ions. Next to the experimental work, attention was paid to the mechanisms taking place in the proposed concept. Here, a simulation model was developed, considering gas/liquid mass transfer of TCE and ozone, axial liquid dispersion, advective gas and liquid transport and about 29 chemical reaction steps. The modelling allowed a better understanding of the technique and gives insight in its possibilities and limitations. Finally, it can be concluded that the proposed technique shows interesting perspectives: it is able to transform chlorine in chlorinated solvents into chloride ions effectively at ambient temperature conditions.

Until now there has been little uniformity in the approach of odour nuisance problems in Flanders. A switch to a standardised and scientifically underpinned approach is essential and is currently in full development. This paper mainly discusses the results of five year research on odour concentration standard developments in Flanders, executed in the period 1996-2000. The research was focused on five pilot sectors: pig farms, slaughterhouses, paint spray installations, sewage treatment plants and textile plants. The general approach of the method to determine the dose-response relation was found to be sufficient. The methodology used is fully described in the paper presented by Van Broeck and Van Langenhove at the CIWEM and IAWQ Joint International Conference on Control and Prevention of Odours in the Water Industry in September 1999. For each location (16 locations in total) an unambiguous dose-response relation could be derived (rising nuisance for rising concentrations). In most cases, a “no effect” level could be determined. The background percentage nuisance fluctuated between 0 and 15%. For the sectors of the slaughterhouses, paint spray installations and sewage treatment plants a no effect level was 0.5, 2.0 and 0.5 sniffing units m−3 as 98th percentile (sniffing units are odour concentrations measured by means of sniffing measurements on the field) was determined. For the sectors of the textile plants and pig farms, no unambiguous no effect level was found. Currently research is undertaken to translate the no effect levels to odour standards. Other initiatives, taken to underpin the Flemish odour regulations, such as the development of an odour source inventory and a complaint handling system, are also briefly discussed.

Sniffing measurement campaigns are a commonly used technique in Flanders to estimate the impact of an odour emission source. The Department of Organic Chemistry at Ghent University has developed its own sniffing strategy throughout the last ten years. The method uses, in essence, the technique of plotting odour perception areas and calculation of total odour emission rates based on maximum odour perception distance. 566 sniffing measurements, executed from 1990 until 1999 around industrial and agricultural odour sources were collected in a database for statistical analysis. Short-term dispersion modelling was executed using four different models, two of them based on Bultynck-Malet dispersion parameters, and two based on Pasquill dispersion parameters. Results from this analysis demonstrate some causes of variance in calculated emissions and show the fitness of each model. From the results of the sniffing teams, which are expressed as sniffing units (SU) instead of odour units (OU, OUE) to underline the difference in methodological approach, the overall odorous emission can be calculated, using short-term atmospheric dispersion models. In a second step, long-term dispersion models can be used to calculate isopercentile contour plots. According to our experience the short-term atmospheric model is a source of “noise” in the method since calculated standard deviations on calculated emissions are larger than standard deviations in the observed maximum distance for odour perception. This will be illustrated by presenting results from the evaluation of composting plants and animal farm houses.

The purpose of the project described in this paper was to develop a procedure to determine odour emissions at existing and new intensive animal farming houses. The procedure should be scientifically valid and preferably applicable on a large scale at reasonable costs. In this project odour emissions were measured during one year at the same farm. Measurements included 20 olfactometric sampling days and 50 sniffing measurements, all spread over one year. For each olfactometric sampling day, samples were taken in duplicate for the different pig categories. The olfactometric analysis resulted in the determination of odour emission factors for growing/fattening pigs, weaned piglets, dry sows and farrowing sows. The influence of external parameters (ventilation rate, inside temperature, outside temperature, pen dirtiness, number of pigs and their weight) was examined. Good correlation between the odour emission and an external parameter could only be found for the ventilation rate (r = 0.98) and outside temperature (r = 0.87). The sniffing measurements resulted in maximal odour perception distances and odour emissions calculated with short and long term dispersion models. No significant influence of the outside temperature (season) could be found here. The results of the olfactometric and sniffing measurements will be presented, including a combination of both techniques to determine the odour emission of an agricultural construction.

The direct derivatisation of acetic acid with n-hexyl chloroformate and with benzyl bromide in water was evaluated. With n-hexyl chloroformate, acetic acid did not give the n-hexyl acetate derivative, but the reaction of acetic acid with benzyl bromide in aqueous solution resulted in the formation of benzyl acetate. The derivatisation of acetic acid with benzyl bromide and the headspace solid-phase microextraction (SPME) of benzyl acetate were optimised. Under optimum conditions, the limit of detection for acetic acid was 260 nM, and the relative standard deviation of the overall procedure at 1.10(-4) M acetic acid was 15.6% (n = 10). A linear response was obtained in the 1 x 10(-4) to 5 x 10(-6) M concentration range (R2 = 0.993, n = 6). Although Carbowax-divinylbenzene (CW-DVB)-coated fibres exhibited a higher extraction capacity for benzyl acetate, polyacrylate (PA) was selected, because its mechanical stability was better than that of CW-DVB fibres. Moreover, the relative standard deviation of the SPME was better with PA (1.5%, n = 10 at 1 x 10(-5) M) than with CW-DVB-coated fibres (8.0%, n = 10 at 1 x 10(-5) M). Thus, a new analytical method for the quantitative determination of micromolar concentrations of acetic acid in the aqueous phase was developed. This method is based on water-phase derivatisation with benzyl bromide, headspace SPME with PA fibres and GC-FID. It was observed experimentally that benzyl alcohol formed by hydrolysis of the reagent affected the fibre-gas phase partitioning of benzyl acetate.

The sonolysis at 520 kHz of the four monohalogenated benzenes, fluoro- (FB), chloro- (CB), bromo- (BB) and iodobenzene (IB) at different initial concentrations, 0.5, 1 and 2 mM, was studied. The sonolysis rate of all four compounds depends on the initial concentration. During sonolysis of FB, CB, BB and IB analogous apolar organic degradation products were determined, indicating that all four monohalogenated benzenes degrade following a similar degradation mechanism. The relative yield of the different degradation products was different, as was shown for the degradation product benzene. A previously developed kinetic model was applied to the sonolysis of the monohalogenated benzenes and a good correlation between experimental and simulated concentration versus time profiles was obtained for all four compounds. By comparing the influence of the different monohalogenated benzenes on their own sonolysis rate, it could be deduced that the proportionality between their concentration in the cavitation bubbles and their concentration in the bulk solution depends on their aqueous diffusion coefficient rather than on their Henry's law coefficient.

A gas mixture containing ppbv concentrations of volatile chlorinated and aromatic hydrocarbons was prepared in helium, nitrogen, or argon in a plastic (Nalophan) bag, in which it was found the mixture could be safely stored for several days. Samples of the mixture were subsequently analyzed by gas chromatography after direct cryotrapping in an empty metal U-tube. The cooling medium used was liquid nitrogen, liquid argon, or a dry ice-acetone slurry (197 K). The efficiency of cryotrapping in liquid nitrogen was over 90% when the aromatic hydrocarbon mixture was prepared in the helium matrix, but between 50 and 70% when it was prepared in nitrogen or argon, the recovery from the argon matrix being somewhat higher. The poor recovery in nitrogen at 77 K and argon at 87 K was explained by the reduced rate of diffusion to the wall owing to mist or aerosol formation. At 197 K condensation was negligible if the partial pressures were lower than the saturated vapor pressures.

This paper attempts to quantify the sustainability of technological processes. It is based on thermodynamics with energy carriers and materials (products, waste, etc.) expressed in the same calculable quantity–exergy (Joule). The results have three considerations. One factor reflects to that extent renewable resources are used. In addition, the technological efficiency has to be accounted for as it affects sustainability. Finally, the results take into account the generation of waste products and the exergy required for converting the waste into products which are harmless or assimilable in the ecosphere. The proposed measure of sustainability has been illustrated for two types of products. In the first illustration, ethanol production was studied. Two routes were investigated, one starting from fossil oil and the other from agricultural products. Additionally, a route based on the synthesis from carbon dioxide and hydrogen was examined, in which hydrogen was generated by splitting water with electricity from photovoltaic solar energy conversion. The second product studied was electricity, generated from the combustion of natural gas or from photovoltaic solar energy conversion. The merit of the obtained results are that they treat technological sustainability not only in qualitative but also in quantitative terms. The insights obtained can help to account for sustainability in the development of new concepts of chemical technology.

The sediment/water (Kd) and octanol/water (Kow) equilibrium partitioning coeAcients have been investigated for volatile chlorinated and monocylic aromatic hydrocarbons in the 2 to 258C tem- perature range. The equilibrium partitioning in closed systems (EPICS) method has been optimized to measure both equilibrium partitioning coeAcients. Sediment/water equilibrium partitioning for a river- ine sediment (organic carbon fraction 4.12%) proved to increase with increasing temperature, showing changes in enthalpy between 2.5 and 12.8 kJmol ˇ1 . A statistical approach showed that for 5 out of 12 compounds investigated this temperature dependence is significant at a = 0.05. Next, the temperature dependence of the octanol/water equilibrium partitioning was investigated for 8 compounds. The octanol/water equilibrium partitioning coeAcients increased with increasing tempera- ture for all compounds, except for toluene. Changes in enthalpies of this process proved to be between ˇ1.0 and 5.2 kJmol ˇ1 . However, the temperature dependence of this process was statistically not sig- nificant (a = 0.05). The log Kd-log Kow relationship showed correlation coeAcients between 0.89 and 0.90 at 2.3, 6.2, 18.6 and 25.08 C( n = 8). Slopes of the linear regression increased with increasing temperature. This was explained by the higher temperature dependence of sediment/water equilibrium partitioning process for compounds with higher Kd coeAcients. # 1999 Elsevier Science Ltd. All rights reserved Key words—volatile organic compounds (VOCs), sediment/water partitioning, sorption, octanol/water partitioning, EPICS

The combination of sonolysis at 520 kHz and oxidation with H 2 O 2 using heterogeneous catalysis was investigated in aqueous solution. To select a convenient heterogeneous catalyst, degradation of 100 mM H 2 O 2 in the presence of 1 mg ml −1 Al 2 O 3 , ZnO, Ni 2 O 3 and CuO was determined. The highest apparent first-order degradation rate was measured for CuO. The most intensive luminescence was observed as well with CuO, and therefore this metal oxide was used as heterogeneous catalyst. No effect of sonication was measured on the CuO-catalysed degradation of 100 mM H 2 O 2 , although sonication affects strongly the specific surface of the CuO-particles. The combination of sonolysis and oxidation with H 2 O 2 /CuO was tested on the degradation of the hydrophilic compound phenol and the hydrophobic volatile compound trichloroethylene (TCE). The degradation of phenol was slower than if additivity of both degradation mechanisms is assumed. Addition of CuO/H 2 O 2 on the other hand did not enhance the degradation rate of TCE at all. TCE does not react with the radicals, probably superoxide radicals, formed by the CuO-catalysed H 2 O 2 decomposition and the formation of cavitations is apparently not increased by adding CuO-particles.