Leaching of potential hazardous elements of coal cleaning rejects

The geochemical characteristics of coal cleaning rejects (CCR) in Santa Catarina State, Brazil, were investigated. Around 3.5 million ton/ year of coal waste are dumped in Santa Catarina State. Coal beneficiation by froth flotation results in large amounts of CCR composed of coaly and mineral matter, the latter characterised by the occurrence of sulphide minerals and a broad array of leachable elements. The total and leachable contents of more than 60 elements were analysed. Atmospheric exposure promotes sulphide oxidation that releases substantial sulphate loads as well as Ca^2?+?, K^?+?, Mg^2?+?, Cl^??? and Al^3?+?. The metals with the most severe discharges were Zn, Cu, Mn, Co, Ni and Cd. Most trace pollutants in the CCR displayed a marked pH-dependent solubility, being immobile in near-neutral samples. The results highlight the complex interactions among mineral matter solubility, pH and the leaching of potentially hazardous elements.     

Carboxymethyl cellulose thiol-imprinted polymers:Synthesis,characterization and selective Hg(Ⅱ) adsorption

Sulfur containing ion imprinted polymers(S-IIPs) were applied for the uptake of Hg(Ⅱ) from aqueous solution. Cysteamine which was used as the ligand for Hg(Ⅱ) complexation, was grafted along the epichlorohydrin crosslinked carboxylated carboxymethyl cellulose polymer chain through an amide reaction. The adsorption ability of S-IIPs towards Hg(Ⅱ)was investigated by kinetic and isotherm models, which, corresponding, showed that the adsorption process followed a pseudo-second-order, fitted well with the Langmuir isotherm with a maximum adsorption capacity of 80 mg/g. Moreover, thermodynamic studies indicated an endothermic and spontaneous reaction with the tendency of an enhanced randomness at the surface of the S-IIPs with temperature increases. S-IIPs indicated a high degree of selectivity towards Hg(Ⅱ) in the presence of Cu~(2+), Zn~(2+), Co~(2+), Pb~(2+)and Cd~(2+).Furthermore, the efficiency of S-IIPs was also evaluated against real samples showing86.78%, 91.88%, and 99.10% recovery for Hg(Ⅱ) wastewater, ground water and tap water,respectively. In this study, the adsorbent was successfully regenerated for five cycles, which allows for their reuse without significant loss of initial adsorption capability.     

Photocatalytic degradation of the diazo dye naphthol blue black in water using MWCNT/Gd,N,S-TiO2 nanocomposites under simulated solar light

A simple sol–gel method was employed to prepare gadolinium, nitrogen and sulphur tridoped titania decorated on oxidised multiwalled carbon nanotubes (MWCNT/Gd,N,S-TiO₂), using titanium (IV) butoxide and thiourea as titanium and nitrogen and sulphur source, respectively. Samples of varying gadolinium loadings (0.2%, 0.6%, 1.0% and 3.0% Gd^3 +) relative to titania were prepared to investigate the effect of gadolinium loading and the amounts of carbon nanotubes, nitrogen and sulphur were kept constant for all the samples. Furthermore, the prepared nanocomposites were evaluated for the degradation of naphthol blue black (NBB) in water under simulated solar light irradiation. Higher degradation efficiency (95.7%) was recorded for the MWCNT/Gd,N,S-TiO₂ (0.6% Gd) nanocomposites. The higher photocatalytic activity is attributed to the combined effect of improved visible light absorption and charge separation due to the synergistic effect of Gd, MWCNTs, N, S and TiO₂. Total organic carbon (TOC) analysis revealed a higher degree of complete mineralisation of naphthol blue black (78.0% TOC removal) which minimises the possible formation of toxic degradation by-products such as the aromatic amines. The MWCNT/Gd,N,S-TiO₂ (0.6% Gd) was fairly stable and could be re-used for five times, reaching a maximum degradation efficiency of 91.8% after the five cycles.     

Metals and metalloid bioconcentrations in the tissues of Typha latifolia grown in the four interconnected ponds of a domestic landfill site

The uptake of metals in roots and their transfer to rhizomes and above-ground plant parts (stems, leaves) of cattails (Typha latifolia L.) were studied in leachates from a domestic landfill site (Etueffont, France) and treated in a natural lagooning system. Plant parts and corresponding water and sediment samples were taken at the inflow and outflow points of the four ponds at the beginning and at the end of the growing season. Concentrations of As, Cd, Cr, Cu, Fe, Mn, Ni and Zn in the different compartments were estimated and their removal efficiency assessed, reaching more than 90% for Fe, Mn and Ni in spring and fall as well in the water compartment. The above- and below-ground cattail biomass varied from 0.21 to 0.85, and 0.34 to 1.24 kg dry weight/m², respectively, the highest values being recorded in the fourth pond in spring 2011. The root system was the first site of accumulation before the rhizome, stem and leaves. The highest metal concentration was observed in roots from cattails growing at the inflow of the system''s first pond. The trend in the average trace element concentrations in the cattail plant organs can generally be expressed as: Fe > Mn > As > Zn > Cr > Cu > Ni > Cd for both spring and fall. While T. latifolia removes trace elements efficiently from landfill leachates, attention should also be paid to the negative effects of these elements on plant growth.     

Recovery of organic wastes in the Spanish wine industry. Technical,economic and environmental analyses of the composting process

The main organic wastes produced in modern wine industries include grape pomace (62%), lees (14%), stalk (12%) and dewatered sludge (12%). Some of these wastes are being used as by-products (grape pomace and lees) whereas the rest of organic wastes (stalk and wastewater sludge) has been traditionally incinerated or disposed in landfill. In this work, composting is proposed for the recovery of stalk and wastewater sludge to produce a sanitized organic amendment for application in the vineyard, closing the organic matter cycle. The environmental and economical analyses of the different alternatives to manage organic wastes from the wine industry are also presented. Composting costs are almost negligible when compared to other management options. From the environmental point of view, in-situ composting presents the best performance in 8 of the 10 impact categories analysed. Finally, the energy balance shows that the 4 composting systems involved less energy than the systems based on Mineral Fertilizer consumption.     

Why do snakes have eyes? The (non-)effect of blindness in island tiger snakes (Notechis scutatus)

Large (to >1 m), diurnally active tiger snakes (Notechis scutatus) are abundant on Carnac Island, near the coast of Western Australia. Our behavioural and mark-recapture studies provide the first ecological data on this population, and reveal a surprising phenomenon. Many adult tiger snakes have had their eyes destroyed, apparently during nest defence, by silver gulls (Larus novaehollandiae). This loss of vision did not reduce the snakes' body condition (mass relative to length), or their rates of growth or survival (measured over a 12-month period). Blind male snakes trail-followed females, and mated successfully. Thus, destruction of a major sensory modality had no detectable effect on these predators. This result is strongly counter-intuitive, but mirrors an earlier report of congenital blindness (without ill-effects) in American viperid snakes. Similarities between the two systems (island populations, highly venomous snakes, reliance on sessile prey) clarify the circumstances under which the loss of vision does not reduce an organism's viability. These natural experiments support Gans' hypothesis of “momentarily excessive construction” in that the snakes possess a complex organ system that they do not actually require for successful feeding, survival or reproduction. Received: 30 November 1998 / Received in revised form: 24 April 1999 / Accepted: 9 May 1999     

Multiple-objective evaluation of wastewater treatment plant control alternatives

Besides the evaluation of the environmental issues, the correct assessment of wastewater treatment plants (WWTP) should take into account several objectives such as: economic e.g. operation costs; technical e.g. risk of suffering microbiology-related TSS separation problems; or legal e.g. accomplishment with the effluent standards in terms of the different pollution loads. For this reason, the main objective of this paper is to show the benefits of complementing the environmental assessment carried out by life cycle assessment with economical, technical and legal criteria. Using a preliminary version of the BSM2 as a case study, different combinations of controllers are implemented, simulated and evaluated. In the following step, the resulting multi-criteria matrix is mined using multivariate statistical techniques. The results showed that the presence of an external carbon source addition, the type of aeration system and the TSS controller are the key elements creating the differences amongst the alternatives. Also, it was possible to characterize the different control strategies according to a set of aggregated criteria. Additionally, the existing synergies amongst different objectives and their consequent trade-offs were identified. Finally, it was discovered that from the initial extensive list of evaluation criteria, only a small set of five are really discriminant, being useful to differentiate within the generated alternatives.     

The use of life cycle assessment for the comparison of biowaste composting at home and full scale

Environmental impacts and gaseous emissions associated to home and industrial composting of the source-separated organic fraction of municipal solid waste have been evaluated using the environmental tool of life cycle assessment (LCA). Experimental data of both scenarios were experimentally collected. The functional unit used was one ton of organic waste. Ammonia, methane and nitrous oxide released from home composting (HC) were more than five times higher than those of industrial composting (IC) but the latter involved within 2 and 53 times more consumption or generation of transport, energy, water, infrastructures, waste and Volatile Organic Compounds (VOCs) emissions than HC. Therefore, results indicated that IC was more impacting than HC for four of the impact categories considered (abiotic depletion, ozone layer depletion, photochemical oxidation and cumulative energy demand) and less impacting for the other three (acidification, eutrophication and global warming). Production of composting bin and gaseous emissions are the main responsible for the HC impacts, whereas for IC the main contributions come from collection and transportation of organic waste, electricity consumption, dumped waste and VOCs emission. These results suggest that HC may be an interesting alternative or complement to IC in low density areas of population.     

Habitat use by loggerhead sea turtles <Emphasis Type="Italic">Caretta caretta</Emphasis> off the coast of eastern Spain results in a high vulnerability to neritic fishing gear

Previous studies of loggerhead sea turtles have concluded that drifting longlines were the main threat for immature specimens in the western Mediterranean, because immature loggerhead sea turtles mainly inhabit oceanic waters. However, recent aerial surveys have revealed large numbers of immature loggerhead sea turtles over the continental shelf of eastern mainland Spain, where turtles are exposed to neritic fishing gears but not to drifting longlines. We satellite-tracked seven loggerhead sea turtles (minimum straight carapace length (SCLmin) range: 36.5–55.0 cm) to assess whether the turtles in this region are vagrants from the adjoining oceanic regions or whether these loggerheads mostly inhabit the continental shelf. Satellite-tracking revealed that six of the tagged turtles avoided the oceanic realm and made extended use of the continental shelf, whereas only one individual could be considered a true vagrant as it avoided the continental shelf and primarily used the oceanic habitat. These results are in sharp contrast with those previously reported for immature loggerhead sea turtles of similar size from the south-western Mediterranean and fit well a relaxed ontogenic model that was recently proposed for loggerhead sea turtles in the central Mediterranean. Furthermore, these results demonstrate the vulnerability of loggerhead sea turtles of eastern mainland Spain to neritic fishing gears, as three of the seven turtles died and one was bycaught incidentally while being tracked over the continental shelf.