Abstract: A new method to estimate case specific prediction uncertainty for univariate trilinear partial least squares (tri-PLS1) regression is introduced. This method is, from a theoretical point of view, the most exact finite sample approximation to true prediction uncertainty that has been reported up till now. Using the new method, different error sources can be propagated, which is an advantage that cannot be offered by data driven approaches such as the bootstrap. In a concise example, it is illustrated how the method can be applied. In the Appendix, efficient algorithms are presented to compute the estimates required.

Abstract: Nitrate contamination of groundwater has been recognized as a significant environmental problem world widely. Sulfur-driven mixotrophic denitrification has been demonstrated as a promising groundwater treatment process, which though plays an important role in nitrous oxide (N2O) emissions, significantly contributing to the overall carbon footprint of the system. However, the current process optimizations only focus on nitrate removal and excess sulfate control, with the N2O emission being ignored. In this work, an integrated mathematical model was proposed to evaluate the N2O emission as well as the excess sulfate production and carbon source utilization in sulfur-driven mixotrophic denitrification process. In this model, autotrophic and heterotrophic denitrifiers use their corresponding electron donors (sulfur and organic matter, respectively) to reduce nitrate to nitrogen gas, with each modeled as three-step denitrification (NO3 to N-2 via NO2 and N2O) driven by sulfur or organic matter to describe all potential N2O accumulation steps. The developed model, employing model parameters previously reported in literature, was successfully validated using N2O and sulfate data from two mixotrophic denitrification systems with different initial conditions. Modeling results revealed substantial N2O accumulation due to the relatively low autotrophic N2O reduction activity as compared to heterotrophic N2O reduction activity, explaining the observation that higher carbon source addition resulted in lower N2O accumulation in sulfur-driven mixotrophic denitrifying system. Based on the validated model, optimizations of the overall system performance were carried out. Application of the model to simulate long-term operations of sulfur-driven mixotrophic denitrification process indicates that longer sludge retention time reduces N2O emission due to better retention of active biomass. High-level total nitrogen removal with significant N2O emission mitigation, appropriate excess sulfate control and maximized COD utilization can be achieved simultaneously through controlling the influent nitrate and COD concentrations. (C) 2017 Elsevier Ltd. All rights reserved.

Abstract: A novel heap leaching method was investigated for selective removal of chromium (Cr) and-vanadium (V) from ferrochromium (FeCr) and stainless steel (SS) slags. In particular, alkaline oxidative heap leaching was simulated on lab-scale by batch and column leaching tests. The results show a selective leaching of Cr (11-19%) and V (7.0-7.5%) after 64 days of column leaching, with a very low dissolution (<2.2% (FeCr slag) and <0.15% (SS slag)) of matrix elements (e.g. Al, Fe, Si, Mg, Ca), when NaOCl is applied as oxidation agent and NaOH as alkaline agent. Furthermore, the used leaching liquor is reactive for a longer period of time, indicating that circulation of leaching liquor could be possible. Finally, the experimental results were fed into a first-order model which predicts that Cr will continue to leach from the tested slags for 4-5 years at a chosen infiltration rate of 73,000 l/(y m(2)). (C) 2016 Elsevier B.V. All rights reserved.

Abstract: Children's exposure to air pollution requires a focus on air quality in places where they spend most time, e.g. in schools. Therefore, understanding how indoor elemental concentrations relate the outdoor ones is necessary to create healthy indoor school environment. The aims of this study were to examine the elemental composition of particulate matter (PM1, PM2.5, PM10) in the school and also to investigate to what degree indoor elemental concentrations are affected by outdoor air or generated inside the school. The measurements were performed inside and outside the public school building in the centre of the city. It was observed that concentrations of most elements were higher at school than outside. The dominant elements in PM1 both indoors and outdoors were S, Cl, K, and Zn. PM2.5 and PM10 fractions inside the school were clearly enriched in elements of mineral origin, additionally S, Zn, K and Cl were also present in high concentrations both indoors and outdoors. Results suggested that a significant contribution to indoor Zn, Pb and S concentrations in the PM2.5 fraction was from penetration of outdoor air. 88%, 80% and 90% of the observed total variations in indoor concentrations of Zn, Pb, and S were explained by the linear relationship between indoor and outdoor concentrations. The lack of correlation between indoor and outdoor concentrations obtained for Si, Ca, Ti, Sr indicated that these metals were more likely to originate from indoor sources. (C) 2013 Elsevier Ltd. All rights reserved.

Abstract: The conventional treatment of municipal wastewater by means of activated sludge is typically energy demanding. Here, the potential benefits of: (1) the optimization of mesophilic digestion; and (2) transitioning to thermophilic sludge digestion in three wastewater treatment plants (Tilburg-Noord, Land van Cuijk and Bath) in the Netherlands is evaluated, including a full-scale trial validation in Bath. In Tilburg-Noord, thermophilic sludge digestion covered the energy requirements of the plant (102%), whereas 111% of sludge operational treatment costs could be covered in Bath. Thermophilic sludge digestion also resulted in a strong increase in nutrient release. The potential for nutrient recovery was evaluated via: (1) stripping/absorption of ammonium; (2) autotrophic removal of ammonium via partial nitritation/anammox; and (3) struvite precipitation. This research shows that optimization of sludge digestion may lead to a strong increase in energy recovery, sludge treatment costs reduction, and the potential for advanced nutrient management in full-scale sewage treatment plants. (C) 2016 Elsevier Ltd. All rights reserved.

Abstract: The feasibility of algae harvesting with submerged flat panel membranes was investigated as pre-concentration step prior to centrifugation. Polishing of the supernatant coming from the centrifuge was evaluated as well. The effect of membrane polymer (polyvinyl chloride [PVC], polyethersulfone polyvinyl-pyrollidone [PES-PVP], poly vinylidene fluoride [PVDF]), pore size (microfiltration [MF], ultrafiltration [UF]), algae cell concentrations and species were investigated at lab-scale. In addition, backwashing as fouling control was compared to standard relaxation. PVDF was the superior polymer, and UF showed better fouling resistance. Backwashing outperformed relaxation in fouling control. The backwashable membranes allowed up to 300% higher fluxes compared to commercial flat panel benchmark (PVC) membranes. Estimations on energy consumption for membrane filtration followed by centrifugation revealed relatively low values of 0.169 kW h/kg of dry weight of algae compared to 0.5 kW h/kg for algae harvesting via classical centrifuge alone. (C) 2012 Elsevier Ltd. All rights reserved.

Abstract: In the present study, an active site titration method is demonstrated, to determine the amount of active enzyme (beta-galactosidase), immobilized on a support. Two types of supports were investigated, viz, amino acrylic resin and a mixed matrix membrane. Furthermore, 2',4'-dinitrophenyl 2-deoxy-2-fluoro-beta-D-galactopyranoside was used as an inhibitor for the active site titration of immobilized beta-galactosidase obtained from Kluyveromyces lactis. Using the active site titration, approximately 8.3 mg of active enzyme was found on 1 g of dried commercially available SPRIN imibond, which is an amino acrylic resin with covalently bound beta-galactosidase obtained from K. lactis. However, this method, in its present form, was not effective on the mixed matrix membranes due to the irreversible partial adsorption of the leaving group (2',4'-dinitrophenolate) by the membrane. This observation implied that it is important to investigate interactions between the support and the used inhibitor and leaving group. (C) 2014 Elsevier B.V. All rights reserved.

Abstract: Elemental and water-soluble ionic compounds (WSICs) of atmospheric aerosols (total suspended particulate TSP) and some gaseous pollutants (SO2, NO2 and O3) from a coastal, semi-urban and rural site in and near Dar es Salaam, Tanzania were investigated during dry and wet seasons of January 2005November 2007. Na+, Ca2+, SO42−, NO3− and Cl− made up the dominant fraction of WSICs during the dry season with average concentrations ranging from non-detectable (n.d.)5.4, 0.262.6, 0.7414.7, 0.41.5 and 1.13.4 μg m−3, respectively, while in the wet season, from n.d. up to 1.7, 1.2, 4.4, 2.1 and 3.0 μg m−3, respectively. The total air concentrations of the detected elements (Al, Si, S, Cl, K, Ca, Fe and Zn) showed seasonal and site-specific variation in the range of 7.526.6 with an average of 14.5 μg m−3. Most of the air concentrations of pollutants were observed to decrease with increasing distance from the coastal site, which is under urban and industrial pollutant emissions. Sulphur and nitrogen oxidation ratios during the dry season ranged from 0.08 to 0.91 and 0.013 to 0.049, respectively, while they were between 0.090.65 and 0.0020.095, respectively, in the wet season. These values indicate the photochemical oxidation of SO2 and a high extent of NO3−formation in the atmosphere. Neutralization ratios revealed the presence of acidic SO42− and NO3− aerosols. Principal component analysis identified sea spray, local combustion, vehicular traffic, biomass burning and re-suspended road dust as dominant sources of aerosols at the studied coastal and semi-urban sites. However, at the rural site, besides sea spray, crustal sources, soil dust re-suspension and long-range transport are the possible origins of suspended particulates.

Abstract: The results of Chemkar PM10, the first large scale chemical characterisation project of PM10 in Flanders are presented. Between September 2006 and September 2007 a total of 365 PM10 samples were collected by sampling every sixth day at six different sites in Flanders (Belgium) varying in character from urban background to rural. Samples were analysed for a series of elements, elemental and organic carbon, 13C/12C- and 15N/14N-isotopic ratios, and water-soluble ions. At three sites extra sampling was carried out to determine PAHs by means of a novel technique that uses sorption tubes consisting of polydimethylsiloxane (PDMS) foam, PDMS particles and a TENAX TA bed. Results showed that the most important fractions were secondary inorganic ions (nitrate, sulphate and ammonium): 41% (12.6 μg m−3), organic matter: 20% (6.1 μg m−3), crustal matter: 14% (4.3 μg m−3), sea salt: 8% (2.4 μg m−3) and elemental carbon: 4% (1.2 μg m−3). Although the general composition profile was rather similar for the six sites, substantial differences could be observed for some main components and for several trace metals such as chromium, copper, zinc, arsenic and lead. Although the average sum of the PAH 16 was quite variable between the three sites (between 132 and 248 ng m−3) the average sum of the PAH 7 was between 7 and 9 ng m−3 for the three sites. The largest relative differences between sites were found for elemental carbon and crustal matter, thereby indicating that there is some potential for local measures to reduce the concentrations of particulate matter by a few μg m−3. Both for carbon and nitrogen isotopic ratios significant differences in time were observed. Isotopic differences in location could only be detected for carbon.

Abstract: Iron (Fe) and other trace elements such as Zn, Mn, Ni and Cu are known as key-factors in marine biogeochemical cycles. It is believed that ocean primary productivity blooms in iron deficient regions can be triggered by iron in aeolian dust. Up to now, scarce aerosol elemental composition, based on measurements over sea at the Western South Atlantic (WSA), exist. An association between the Patagonian semi-desert dust/Fe and chlorophyll-a variability at the Argentinean continental shelf is essentially inferred from models. We present here experimental data of Fe enriched aerosols over the WSA between latitudes 22°S62°S, during 4 oceanographic campaigns between 2002 and 2005. These data allowed inferring the atmospheric Fe flux onto different latitudinal bands which varied from 30.4 to 1688 nmolFe m−2 day−1 (October 29thNovember 15th, 2003); 5.831586 nmolFe m−2 day−1 (February 15thMarch 6th, 2004) and 4.73586 nmolFe m−2 day−1(October 21stNovember 5th, 2005).

Abstract: The major threat to clean air in developed and industrializing countries is now posed by traffic emissions. The effects of traffic road modifications on the air quality are, however, rarely reported in the literature. The aim of this study was to determine the influence of the modernization and renovation of a traffic artery in the region of Mortsel (Antwerp, Belgium) on the concentration of volatile organic compounds such as: benzene, toluene, ethylbenzene and m-, p-, o-xylenes (BTEX). The original goal of the reconstruction works was to reduce the traffic lanes of one of the busiest streets in Antwerp, in order to discourage the road traffic and in consequence also to improve the air quality in this region. The average concentrations of BTEX before these works in 2003 were: 1.6, 7.0, 0.9, 2.3, and 0.9 ìg/m3, for benzene, toluene, ethylbenzene, m + p xylenes, and o-xylene, respectively. However, after the completion of the works, in 2005, they were slightly higher: 2.5, 9.5, 1.6, 3.4, and 1.3 ìg/m3, respectively. The scatter plots of benzene against toluene, ethylbenzene and xylenes in 2003 and 2005 showed very good correlations. This fact indicated that all of the measured compounds originated from the same source, namely the road traffic. Moreover, the data obtained from an air-monitoring station at less than 6 km distance from the sampling site (operated by the Flemish Environment Agency, and located in Borgerhout, Antwerp), confirmed the lack of influence of background concentrations of BTEX. The obtained results led to the conclusion that the reduction of the number of traffic lanes had apparently increased the traffic jams and also increased the emission from cars. Therefore, these modernization works had even a negative impact on the local concentration of traffic-related pollutants as BTEX.

Abstract: Air pollution caused by the lime production industry has become a serious problem with potential effects to human health, especially in developing countries. Colombo is a city included in the Metropolitan Region of Curitiba (capital of Parana State) in South Brazil. In Colombo city, a correlation has been shown between the lime production and the number of persons who need respiratory treatment in a local hospital, indicating that the lime industry can cause deleterious health effects in the exposed workers and population. This research was conducted to deal firstly with the characterization of the size distribution and chemical compositions of particles emitted from lime manufacturing and subsequently to assess the deposition rate of inhaled dolomitic lime aerosol particles in the human respiratory tract. The elemental chemical composition and particle size of individual atmospheric particles was quantitatively elucidated, including low-Z components like C, N and 0, as well as higher-Z elements, using automated electron probe microanalysis. Information concerning the bulk composition is provided by energy-dispersive X-ray detection. The majority of the respirable particulate matter identified was composed of aluminosilicates, Ca-Mg oxides, carbon-rich particles, mixtures of organic particles and Ca-Mg carbonates, soot and biogenic particles. In view of the chemical composition and size distribution of the aerosol particles, local deposition efficiencies in the human respiratory system were calculated, revealing the deposition of CaO center dot MgO at extrathoracic, tracheobronchial and pulmonary levels. The results of this study offer evidence to the threat of the fine and coarse particles emitted from dolomite lime manufacturing, allowing policy-makers to better focus their mitigation strategies in an effective way, as well as to the dolomite producers for the purpose of designing and/or implementing improved emission controls.