Ecotoxicological assessment of metal-polluted urban soils using bioassays with three soil invertebrates

This study aimed at assessing the quality of urban soils by integrating chemical and ecotoxicological approaches. Soils from five sites in downtown Naples, Italy, were sampled and characterized for physical-chemical properties and total and water-extractable metal concentrations. Bioassays with Eisenia andrei, Enchytraeus crypticus and Folsomia candida were performed to assess toxicity of the soils, using survival, reproduction and growth as the endpoints. Metal bioaccumulation in the animals was also measured. The properties and metal concentrations of the soils strongly differed. Metal bioaccumulation was related with total metal concentrations in soil and was highest in E. crypticus, which was more sensitive than E. andrei and F. candida. Responses of the three species to the investigated soils seemed due to both metal contamination and soil properties.     

The hydraulic separator Multidune: preliminary tests on fluid-dynamic features and plastic separation feasibility

Recycling of plastic materials is a rapidly developing discipline because of environmental awareness, the need to conserve materials and energy, and the growing demand to increase the production economy. The main problem in plastics recovery and recycling is related to the variety of plastic wastes, even if selective collection occurs. Therefore, plastic materials can be recycled either as mixtures or as single types, separating the different typologies by their physical (size, specific mass, etc.) and/or chemical properties. However, separation of plastics in single typologies by traditional processes and devices is difficult due to their typical low variability in properties. This paper presents a new research development for recycling industry: the Multidune separator. This is a device constructed from a sequence of parallel semi-cylindrical tubes of transparent plastic welded together in a plane. The lower half is shifted laterally and then fixed relative to the upper half. Flow is then induced in the lateral direction normal to the axis of the tubes, creating a main flow channel and two recirculation zones. This apparatus creates a differential transport of particles of low specific mass, near to 1g/cm(3), allowing their separation. The flow field in the Multidune separator is studied via Particle Tracking Velocimetry (PTV). Eulerian analysis of the data is performed to gather information about the fluid-dynamics features established by different hydraulic heads at the inlet of the Multidune. Preliminary tests on monomaterial samples have been performed, varying several operative parameters to determine the best set of values. Therefore, separation tests have been executed on composite samples, obtaining satisfactory results in terms of plastic separation feasibility.     

Utilization of UV‐A and UV‐C radiation in advanced oxidation processes with the intention of removing color and organic matter from the gross leachate of a stabilized sanitary landfill

The present work investigated color and biochemical oxygen demand (COD) removal from treated landfill leachate via advanced oxidative processes (AOPs) artificially emitted. The AOP H₂O₂/UV, TiO₂/UV, and photolysis were tested in two bench‐scale photoreactors: The first one with UV‐C lamp and the other with UV‐A lamp associated or not with coagulation / flocculation pretreatment. Crude leachate samples with pH ranging from 8 to 3 were used, and time varied in 30, 45, and 60 minutes. Experiments were performed in two stages: step 1 with a 20 mL volume from each sample and step 2 with repetition of the best results from the previous step, adopting the 150 mL volume. In step 1, the AOP applied in the crude leachate sample showed the best results, standing out H₂O₂/UV‐C with 30 minutes and TiO₂/UV‐A with 60 minutes. In step 2, H₂O₂/UV‐C had a 60% color removal and 25% COD reduction, while TiO₂/UV‐A had a 10% color removal and 20% COD reduction. Therefore, the H₂O₂/UV‐C process was the most efficient, because the complex characteristics of the effluent interfered in the TiO₂/UV‐A efficiency, but it is necessary to eliminate the process interferences. The use of artificial radiation is a viable alternative; however, it can be costly, being relevant in the associations between processes with artificial UV and solar UV, as the natural radiation becomes more attractive and allows the process operating costs reduction.     

Nitrate and nitrite injection during municipal solid waste anaerobic biodegradation

Nitrified leachate recirculation has been proposed as a promising strategy for sustainable landfill management. In four test reactors, nitrate or nitrite was added (250 mg N-NO(x)(-)L(-1)) during municipal solid waste biodegradation. Nitrogen-oxides reduction reactions were monitored. Denitrification was the main nitrogen reducing reaction observed. On one hand, during the acidogenic waste degradation phase, as high amounts of volatile fatty acids (VFA) were present, nitrogen-oxides reductions were interpreted as heterotrophic denitrifications. On the other hand, denitrification reactions occurring during the late methanogenic phase were accompanied by sulphate productions and, as VFA were not detected, it was probably an autotrophic reaction. Denitrification inhibition was observed once. Ammonium concentration increased suggesting the occurrence of a dissimilatory nitrate reduction to ammonium (DNRA). Statistical treatment of analytical data revealed that only H(2)S concentration had a significant negative effect on N(2) production in our system. NO production was observed once when nitrite was injected during the acidogenic phase resulting in a total waste degradation inhibition. These results indicate that the consequences of nitrified leachate recirculation in full-scale landfills need to be carefully examined especially during the acidogenic phase or in the presence of waste containing high quantities of sulphur.     

Current status and perspectives of accelerated carbonation processes on municipal waste combustion residues

The increasing volumes of municipal solid waste produced worldwide are encouraging the development of processes to reduce the environmental impact of this waste stream. Combustion technology can facilitate volume reduction of up to 90%, with the inorganic contaminants being captured in furnace bottom ash, and fly ash/APC residues. The disposal or reuse of these residues is however governed by the potential release of constituent contaminants into the environment. Accelerated carbonation has been shown to have a potential for improving the chemical stability and leaching behaviour of both bottom ash and fly ash/APC residues. However, the efficacy of carbonation depends on whether the method of gas application is direct or indirect. Also important are the mineralogy, chemistry and physical properties of the fresh ash, the carbonation reaction conditions such as temperature, contact time, CO₂ partial pressure and relative humidity. This paper reviews the main issues pertaining to the application of accelerated carbonation to municipal waste combustion residues to elucidate the potential benefits on the stabilization of such residues and for reducing CO₂ emissions. In particular, the modification of ash properties that occur upon carbonation and the CO₂ sequestration potential possible under different conditions are discussed. Although accelerated carbonation is a developing technology, it could be introduced in new incinerator facilities as a “finishing step” for both ash treatment and reduction of CO₂ emissions.     

Synthesis of BiVO4/TiO2 composites and evaluation of their photocatalytic activity under indoor illumination

BiVO₄/TiO₂ composites with different weight ratios have been prepared by coprecipitation-based reactions followed by either thermal or hydrothermal treatment with the aim of evaluating the TiO₂ photosensitization by BiVO₄. The obtained materials present in all cases the desired monoclinic phase of BiVO₄ and anatase phase of TiO₂. Visible light absorption increased with increasing amount of bismuth vanadate. XPS results reveal the surface enrichment of Ti with respect to the bulk composition in samples characterised by a higher content of BiVO₄. The photocatalytic activity of the prepared materials was tested for the degradation of isopropanol in the gas phase under indoor illumination conditions. Although none of the composites was able to improve the activity of TiO₂, the low BiVO₄ containing samples appear as more suitable for further synthesis tuning.     

250-year records of mercury and trace element deposition in two lakes from Cajas National Park,SW Ecuadorian Andes

Environmental Science and Pollution Research - Historical records of trace elements in lake sediments provide source-to-sink information about potentially toxic pollutants across space and time. We...     

Influence of mating order on courtship displays and stored sperm utilization in Hermann's tortoises (Testudo hermanni hermanni)

Sperm storage is widespread in many vertebrate groups, and it is frequently associated with promiscuous mating systems. Chelonian species are one of the most outstanding examples of a promiscuous group capable of long-term sperm storage; specialized structures have evolved within the oviducts of these vertebrates to ensure sperm vitality across reproductive cycles. Thus far, few studies have investigated the factors regulating multiple paternity, sperm usage by females and paternity distribution in successive clutches. This study aimed to investigate the effect of mating order on male mounting and reproductive success in Testudo hermanni hermanni, combining behavioural and genetic data. A series of planned matings were performed, within which experimental females were mated sequentially to two different males under controlled conditions. Observations conducted during experimental matings revealed that courtship displays did not significantly differ between the first and second males to mate with a female. Interactions ending with a mount were characterized by a significantly higher intensity and occurrence of determinate courtship behaviours, for example biting and running after the female. Paternity analysis performed on hatchlings produced from experimental females revealed that 46 % of the clutches were multi-sired. A significant contribution of previous years' partners was still found, thus confirming the long-term sperm storage within the female oviduct in this species. Finally, mating order did not significantly affect the reproductive success of experimental males during the on-going reproductive season.