Performance of sequential anaerobic/aerobic digestion applied to municipal sewage sludge

A promising alternative to conventional single phase processing, the use of sequential anaerobic-aerobic digestion, was extensively investigated on municipal sewage sludge from a full scale wastewater treatment plant. The objective of the work was to evaluate sequential digestion performance by testing the characteristics of the digested sludge in terms of volatile solids (VS), Chemical Oxygen Demand (COD) and nitrogen reduction, biogas production, dewaterability and the content of proteins and polysaccharides. VS removal efficiencies of 32% in the anaerobic phase and 17% in the aerobic one were obtained, and similar COD removal efficiencies (29% anaerobic and 21% aerobic) were also observed. The aerobic stage was also efficient in nitrogen removal providing a decrease of the nitrogen content in the supernatant attributable to nitrification and simultaneous denitrification. Moreover, in the aerobic phase an additional marked removal of proteins and polysaccharides produced in the anaerobic phase was achieved. The sludge dewaterability was evaluated by determining the Optimal Polymer Dose (OPD) and the Capillary Suction Time (CST) and a significant positive effect due to the aerobic stage was observed. Biogas production was close to the upper limit of the range of values reported in the literature in spite of the low anaerobic sludge retention time of 15 days. From a preliminary analysis it was found that the energy demand of the aerobic phase was significantly lower than the recovered energy in the anaerobic phase and the associated additional cost was negligible in comparison to the saving derived from the reduced amount of sludge to be disposed.     

Coastal dune systems and disturbance factors: monitoring and analysis in central Italy

This study describes the conservation status of dune systems in relation to disturbance factors in the coastal stretch of the Viterbo province, Latium Region, Italy. Particular emphasis was given to the bioindication value of plant communities and their sequence. Each plant community was considered as a "habitat" in accordance with Annex I of the Directive 92/43/EU. Stress factors, such as sand dynamic and erosion, and anthropogenic pressures, such as trampling and bathing settlements, influence the sequence of habitats and weaken the system of relations that makes these coenoses to occur in extreme conditions. The choice to carry out surveys along wide transects, recording different data, allowed to explore the use of habitats as bioindicators. Comparing sites characterized by the same extension in a homogeneous area, it was possible to expand the use of canonical correspondence analysis (CCA) as a tool to correlate habitat composition and disturbance factors. The application of CCA showed a high correlation of degradation and habitat loss with coastal erosion, trampling and presence of waste. Furthermore, floristic surveys allowed the application of different biodiversity indices to quantify species richness of sampled areas. The conservation status of the sites investigated was found to be diverse, from the total disappearance of the mobile dune habitats to their complete sequence. The proposed methodology has been useful to fulfill the objective of the work and is applicable to other case studies in the Mediterranean.     

The Viareggio LPG accident: Lessons learnt

On June 29th, 2009 the derailment of a freight train carrying 14 LPG (Liquefied Petroleum Gas) tank-cars near Viareggio, in Italy, caused a massive LPG release. A gas cloud formed and ignited triggering a flash-fire that resulted in 31 fatalities and in extended damages to residential buildings around the railway line. The vulnerability of the area impacted by the flash-fire emerged as the main factor in determining the severity of the final consequences. Important lessons learnt from the accident concern the need of specific regulations and the possible implementation of safety devices for tank-cars carrying LPG and other liquefied gases under pressure. Integrated tools for consequence assessment of heavy gas releases in urban areas may contribute to robust decision making for mitigation and emergency planning.     

An imprecise Fault Tree Analysis for the estimation of the Rate of OCcurrence Of Failure (ROCOF)

The paper proposes an imprecise Fault Tree Analysis in order to characterize systems affected by the lack of reliability data. Differently from other research works, the paper introduces a classification of basic events into two categories, namely Initiators and Enablers. Actually, in real industrial systems some events refer to component failures or process parameter deviations from normal operating conditions (Initiators), whereas others refer to the functioning of safety barriers to be activated on demand (Enablers). As a consequence, the output parameter of interest is not the classical probability of occurrence of the top event, but its Rate of OCcurrence (ROCOF) over a stated period of time. In order to characterize the basic events, interval-valued information supplied by experts are properly aggregated and propagated to the top. To this purpose, the Dempster–Shafer Theory of evidence is proposed as a more appropriate mathematical framework than the classical probabilistic one. The proposed methodology, applied to a real industrial scenario, can be considered a helpful tool to support risk managers working in industrial plants.     

Prenatal ultrasound diagnosis of a case of Pfeiffer syndrome without cloverleaf skull and review of the literature

Pfeiffer syndrome is characterized by bilateral coronal craniosynostosis, midface hypoplasia, beaked nasal tip, broad and medially deviated thumbs and great toes. Originally, it was described in eight persons from three generations in a pedigree consistent with an autosomal dominant transmission. Since then, several reports have documented its high clinical and genetic heterogeneity. The condition is usually detected in the newborn period or later, and very few prenatal ultrasound diagnoses have been reported. We present a case of Pfeiffer syndrome prenatally diagnosed at 20 weeks' gestation, in which the sonographic features of craniosynostosis, hypertelorism associated with an extreme proptosis, and broad thumb led to the diagnosis, confirmed after termination of pregnancy by dysmorphological, pathological and radiological evaluation. DNA analysis of the fibroblast growth factor receptor 2 (FGFR2) showed a missense mutation consisting in a transversion G → C at nucleotide 870. This led to a Trp290Cys amino acidic substitution. We discuss the relevant findings of our and previously published cases. Our report demonstrates that a careful sonographic examination can lead to an early prenatal diagnosis of Pfeiffer syndrome also in cases without cloverleaf skull. Copyright © 2004 John Wiley & Sons, Ltd.     

Tween 20 and Its Major Free Fatty Acids as Carbon Substrates for the Production of Polyhydroxyalkanoates in Pseudomonas aeruginosa ATCC 27853

The ability of Pseudomonas aeruginosa ATCC 27853 to grow and synthesize polyhydroxyalkanoates (PHAs) using Tween 20 as the sole carbon source was investigated. Tween 20 could support cell growth and PHA production. The polymer produced from Tween 20 was compared with those produced from its major free fatty acids components: lauric (C₁₂), myristic (C₁₄), and palmitic (C₁₆) acids. Gas-chromatographic analysis of methanolyzed samples and ¹³C-Nuclear Magnetic Resonance (NMR) showed that the PHAs obtained are composed of even carbon atoms 3-hydroxyalkanoates ranging from C₆ to C₁₄, with C₈ and C₁₀ as the predominant components. The nature of the carbon sources used had little influence on the composition, but was found to be important in determining the average molecular weight, shorter chain fatty acids yielding higher molecular weight products. Fast Atom Bombardment-Mass Spectrometry (FAB-MS) of partially pyrolyzed samples, coupled to statistical analysis, showed that these PHAs are random copolymers.     

Ovarian fluid of receptive females enhances sperm velocity

The females of several internal fertilizers are able to store sperm for a long time, reducing the risk of sperm limitation. However, it also means that males can attempt to mate outside females’ receptive period, potentially increasing the level of sperm competition and exacerbating sexual conflict over mating. The guppy (Poecilia reticulata), an internally fertilizing fish, is a model system of such competition and conflict. Female guppies accept courtship and mate consensually only during receptive periods of the ovarian cycle but receive approximately one (mostly forced) mating attempt per minute both during and outside their sexually receptive phase. In addition, females can store viable sperm for months. We expected that guppy females would disfavour sperm received during their unreceptive period, possibly by modulating the quality and/or quantity of the components present in the ovarian fluid (OF) over the breeding cycle. Ovarian fluid has been shown to affect sperm velocity, a determinant of sperm competition success in this and other fishes. We found that in vitro sperm velocity is slower in OF collected from unreceptive females than in OF from receptive females. Visual stimulation with a potential partner prior to collection did not significantly affect in vitro sperm velocity. These results suggest that sperm received by unreceptive females may be disfavoured as sperm velocity likely affects the migration process and the number of sperm that reach storage sites.     

Registration of polymers in accordance with directive 67/548/EEC

This paper clarifies how polymers are dealt with under the Directive 67/548/EEC. Polymers are a particular group of substances under the Directive 67/548/EEC [1] and amendments [2,3] as they are not listed in the European INventory of Existing Commercial chemical Substances (EINECS [4]) which otherwise lists all substances which were on the European Community Market between 1 January 1971 and 18 September 1981, the ‘existing substances’. Instead, in EINECS polymers are registered under their ultimate building blocks. With the 6th amendment to the Directive [2] polymers became notifiable substances if containing 2% or more of new substance(s) (i.e. as a general rule substances not listed in EINECS), and the reporting criteria were used as definition. With the 7th amendment to the Directive [3] an exact definition was introduced and a special test package, given in Directive 93/105/EEC [5], was designed for polymers to take into account their particular properties. Changing the definition of polymers created a group of substances which under the 6th amendment had been defined as polymers, and could no longer be regarded as polymers under the 7th amendment, the No‐Longer‐Polymers.