Separation of packaging plastics by froth flotation in a continuous pilot plant

The objective of the research was to apply froth flotation to separate post-consumer PET (Polyethylene Terephthalate) from other packaging plastics with similar density, in a continuously operated pilot plant. A representative sample composed of 85% PET, 2.5% PVC (Polyvinyl Chloride) and 11.9% PS (Polystyrene) was subjected to a combination of alkaline treatment and surfactant adsorption followed by froth flotation. A mineral processing pilot plant, owned by a Portuguese mining company, was adapted for this purpose. The experimentation showed that it is possible to produce an almost pure concentrate of PET, containing 83% of the PET in feed, in a single bank of mechanical flotation cells. The concentrate grade attained was 97.2% PET, 1.1% PVC and 1.1% PS. By simulation it was shown that the Portuguese recycling industry specifications can be attained if one cleaning and one scavenger stages are added to the circuit.     

Luminescence in the oxidation of isoproterenol by the superoxide anion radical in dimethyl sulfoxide

Chemiluminescence appearing during oxidation of isoproterenol using chemical system involving superoxide anion radical has been studied. Chemiluminescence and fluorescence spectra were measured. The chemiluminescence spectrum was measured with cut‐off filters and revealed bands with maximum at 440, 480, 550, 640 and 700 nm. The bands at 480, 640 and 700 nm were similar to those observed for singlet oxygen. The fluorescence spectrum exhibited maximum at 560 nm.

The inhibitory effect of several biologically important compounds known as O₂ ^?‐ HO^? and ¹O₂ scavengers on the light emission was studied.

The obtained results indicate that oxidation of isoproterenol by O₂ ^?‐ involves products in the electronically excited states. The data also seem to indicate the protective effect of isoproterenol on the deoxyribose degradation.     

Road traffic impact on urban atmospheric aerosol loading at Oporto,Portugal

At urban areas in south Europe atmospheric aerosol levels are frequently above legislation limits as a result of road traffic and favourable climatic conditions for photochemical formation and dust suspension. Strategies for urban particulate pollution control have to take into account specific regional characteristics and need correct information concerning the sources of the aerosol.With these objectives, the ionic and elemental composition of the fine (PM_2.5) and coarse (PM_2.5–10) aerosol was measured at two contrasting sites in the centre of the city of Oporto, roadside (R) and urban background (UB), during two campaigns, in winter and summer.Application of Spatial Variability Factors, in association with Principal Component/Multilinear Regression/Inter-site Mass Balance Analysis, to aerosol data permitted to identify and quantify 5 main groups of sources, namely direct car emissions, industry, photochemical production, dust suspension and sea salt transport. Traffic strongly influenced PM mass and composition. Direct car emissions and road dust resuspension contributed with 44–66% to the fine aerosol and with 12 to 55% to the coarse particles mass at both sites, showing typically highest loads at roadside. In fine particles secondary origin was also quite important in aerosol loading, principally during summer, with 28–48% mass contribution, at R and UB sites respectively. Sea spray has an important contribution of 18–28% to coarse aerosol mass in the studied area, with a highest relative contribution at UB site.Application of Spatial Variability/Mass Balance Analysis permitted the estimation of traffic contribution to soil dust in both size ranges, across sites and seasons, demonstrating that as much as 80% of present dust can result from road traffic resuspension.     

Assessing relationships among life-cycle environmental impacts with dimension reduction techniques

Nowadays, there is a trend in many countries towards more environmentally benign products and processes. Life-Cycle Assessment (LCA) is a quantitative analysis tool developed and utilized for the evaluation of environmental impacts occurring throughout the entire life-cycle of a product, process or activity. LCA requires a large amount of data in its different phases and can also generate large amounts of results which may be hard to interpret. In order to uncover and visualize the structure of large multidimensional data sets, Multivariate Analysis techniques can help. Hence, in this paper, a methodology using Principal Component Analysis and Multi-Dimensional Scaling is proposed and illustrated by means of two case studies. The first case study evaluates the operation of several wastewater treatment plants. The second case study deals with the environmental evaluation of the cultivation, processing and consumption of mussels. In both case studies, the redundancy present in the data allowed a dimensionality reduction from seven and ten to two dimensions, with a small loss of information. Plotting the environmental impact data in these two dimensions can help visualize, interpret and communicate them.     

Effects of zeolites on cultures of marine micro-algae

GOAL, SCOPE AND BACKGROUND: The cation-exchange capacity of zeolites is well known and has been increasingly explored in different fields with both economic and environmental successes. In aquatic medium with low salinity, zeolites have found multiple applications. However, a review of the literature on the applications of zeolites in salt waters found relatively few articles, including some recently published papers. The purpose of this review is to present the state-of-the-art on applications of using zeolites for amending the trace elemental contents of salt water as well as the implications of this property for promoting marine micro-algal growth. MAIN FEATURES: This paper deals with the following features: Sorption capacity of zeolites including 1. application of zeolites in saltwater, 2. the role of silicon and zeolites on cultures of micro-algae, and 3. the role of organically chelated trace metals. RESULTS: The following competing factors have been identified as effects of zeolites on algal growth in salt water: (i) ammonia decrease: growth inhibition reduced; (ii) macro-nutrients increase, mainly silicon: stimulation of silicon-dependent algae; (iii) trace metals increase (desorption from zeolites) or decrease (adsorption): inhibition or stimulation, depending on the nature of the element and its concentration; and, (iv) changes in the chelating organics exudation: inhibition or stimulation of growth, depending on the (a) nature of the complexed element; (b) bioavailability of the complex; and (c) concentration of the elements simultaneously present in inorganic forms. DISCUSSION: Zeolites have been capable of stimulating the growth of the silicon-demanding marine micro-algae, like diatoms, mainly because they can act as a silicon buffer in seawater. Zeolites can also influence the yield of non-silicon-demanding algae, because the changes they can cause (liberation and adsorption of trace elements) in the composition of the medium. CONCLUSIONS: Zeolites have been capable of stimulating the growth of the marine micro-algae. However, the extent of ion exchange between zeolite and seawater, which conditions the effects, will depend on several factors: (1) initial metal concentration in seawater; (2) levels of trace metals in the zeolites (contaminants); (3) characteristics of the zeolites in terms of both ion-exchange capacity and specific affinities for the different cations; (4) quantity of zeolite per litre of solution; (5) pH and (6) response of the organism in terms of liberation of organic ligands. RECOMMENDATIONS AND PERSPECTIVES: RECOMMENDATIONS: Therefore, a previous investigation in each particular case is recommended, in order to select the zeolitic characteristics and concentrations that will maximize the algal yield. PERSPECTIVES: Stimulation of phytoplankton growth can be economically relevant since phytoplankton constitutes the basis of the marine food webs and is required in fish farming nurseries in the marine aquaculture industry. Zeolites are cheap, only small amounts (few milligrams per liter of culture) are required and the addition of some micro-nutrients may be omitted. Therefore, the inclusion of zeolites in algal cultures in aquaculture may have economic advantages.     

An in-depth look at parent-imposed driving rules: their strengths and weaknesses

Introduction: With a growing interest in increasing parental involvement in teen driving, it is important to find out what parents are already doing. Method This study assessed the content, delivery, rigidity, and consequences of 143 driving rules reported by 24 parent-teen dyads. Results: Strengths included that driving rules covered the full range of concerns, especially night driving limits and passenger limits, and most parents and teens reported that violations would be followed by consequences, especially talk/warn or no driving. Weaknesses included that many rules were not very strict and only half showed parent-teen agreement on content. Conclusions: These findings suggest that teen driving rules are not clearly defined.     

Pinus nigra and Pinus pinaster needles as passive samplers of polycyclic aromatic hydrocarbons

Nine polycyclic aromatic hydrocarbons (PAHs) were analysed in pine needles of different ages (from 6 to 30 months) collected from two species, Pinus nigra and Pinus pinaster, in seven sites located along a transect from a suburban to a rural area of Genoa (Italy). In all sites and for both species, concentrations of more volatile PAHs (phenanthrene, anthracene, fluoranthene, pyrene) were higher than those for other less volatile PAHs, which are preferentially sorbed to airborne particulates (benzo[a]anthracene, chrysene, benzofluoranthenes, benzo[a]pyrene). Concentrations of total PAHs found in P. nigra in the rural sites were, on the average, 2.3 times higher than those in P. pinaster growing nearby. In both pine species, concentrations of volatile PAHs increased according to needle age. Annual trends of other PAHs were more variable, with a general decrease in older needles. P. pinaster needles are shown to be more reliable passive samplers, since they are more resistant to plant diseases, and considerable variation in PAH concentration was observed in P. nigra needles with moulds and fungi.     

Ammonia flux from open-lot dairies: development of measurement methodology and emission factors

Ammonia emissions contribute to the formation of secondary particulate matter (PM) and violations of the National Ambient Air Quality Standard. Ammonia mass concentration measurements were made in February 1999 upwind and downwind of an open-lot dairy in California, using a combination of active bubbler and passive filter samplers. Ammonia fluxes were calculated from concentrations measured at 2, 4, and 10 m above ground at three locations on the downwind edge of the dairy, using micrometeorological techniques. A new method was developed to interpolate fluxes at six additional locations from ammonia concentrations measured at a single height, providing measurements at sufficient spatial resolution along the downwind border of the dairy to account for the heterogeneity of the source. PM measured up- and downwind of the dairy demonstrated insignificant ammonium particle formation in the immediate vicinity of the dairy and negligible contribution of dissociated ammonium nitrate to measured ammonia concentrations. Ammonium nitrate concentrations measured downwind of the dairy ranged from 26 to 0.26 microg m(-3) and from 2 to 43% of total PM2.5 mass concentrations. Measured ammonia fluxes showed that liquid manure retention ponds represented relatively minor sources of ammonia in winter on the dairy studied. Ammonia emission factors derived from the measurements ranged from 19 to 143 g head(-1) day(-1), showing an increase with warmer, drier weather and a decrease with increased relative humidity and lower temperatures.     

Antenatal ultrasonic diagnosis of dyssegmental dysplasia: A case report

Sonographic prenatal diagnosis and management of a pregnancy complicated by dys-segmental dysplasia of the Silverman-Handmaker type are presented. This is a documented case of this type of short-limbed dwarfism presenting in a family of Hispanic-American ancestry.