Paolo De Filippis

Production of stable polypropylene-modified bitumens

The use of polypropylene polymers and copolymers as modifiers for road bitumens appears promising. The problem of stability during storage for long periods at high temperatures can be solved by adding phosphorus compounds, especially polyphosphoric acid, which changes the bitumen structure from sol to gel. It is demonstrated that the stability of polymer-modified bitumens depends not only on the difference in density and viscosity between bitumen and polymer but also on bitumen structure.

Production and characterization of adsorbent materials from sewage sludge by pyrolysis

The conventional sludge disposal options include landfill, application to farmland and forestry and incineration. However, since in the last decade sewage sludge and industrial sludge are being generated in increasing amounts due to the rapid urbanization and industrialization, a growing interest has been devoted in developing cost effective and renewable disposal alternatives. Among them, the manufacture of adsorbents to remove metals from water and wastewater appears to be promising, also considering the high cost of commercial carbons. In this paper copper, zinc and cadmium removal from wastewater using adsorbents produced from pyrolysis of sewage sludge is investigated in comparison with commercial adsorbents. The kinetic of the pyrolytic process was studied, and the adsorbents produced under different pyrolysis conditions were characterized. The adsorption capacity of the pyrolyzed material were estimated in batch tests performed in an activated sludge reactor. Results show that the adsorbent materials obtained by sewage sludge pyrolysis increased organic matter removal in activated sludge systems, and limited the inhibition effects of heavy metals. In addition, a chemical activation of the sludge before the pyrolysis resulted in an increase of the adsorption capacity of the obtained adsorbent.

Comparison of global models of sub-bituminous coal devolatilization by means of thermogravimetric analysis

Coal gasification and combustion are strongly dependent on devolatilization step. Aim of this work is to obtain the parameters of global kinetics of devolatilization of a sub-bituminous coal with high sulfur content. The kinetic parameters are obtained by means of TG experimental data, and applying different approaches to extrapolate the data to industrial relevant conditions. The simpler method is a model-free one which supposes a single step process whose Arrhenius kinetic parameters (A and Ea) have to be determined. Another common approach is the distributed activation energy model (DAEM) which assumes a series of first order parallel reactions occurring and sharing the same pre-exponential factor, A, with a continuous distribution of the activation energy. For the fitting of the experimental data, a numerical solution to DAEM and two approximate methods have been evaluated. Moreover, the results of these kinetic methods based on empirical approaches were compared with simulated data obtained using a more complex model based on percolation theory with cross-linking mechanism and vapor–liquid equilibrium (chemical percolation devolatilization, CPD model), which allows to simulate the coal pyrolysis from volatile yield data.

Automobile shredder residue gasification

Automobile Shredder Residue (ASR) shows a broad chemical composition owing to the presence of different materials, and its high organic content makes it interesting as a source of energy. In this work, a bench scale two-stage reactor is used for gasifying ASR. The reactor shows an efficient ASR gasification, avoiding the formation of difficult to manage char and tar and allowing an easy recovery of energy. The results of the investigation were used to test a simple model based on mass and energy balances and chemical equilibrium, predicting syngas composition including the presence of problematic elements such as sulphur and chlorine. Gasification data calculated by the model agree in a satisfactory way with the experimental ones. Due to the large variation in ASR composition, the model predicts that ASR gasification is industrially feasible only if a blend of ASR and RDF is used as a reactor feed.

Effect of modified Fenton treatment on the thermal behavior of contaminated harbor sediments

This study presents the results of experimental Fenton-like treatments conducted on marine sediment slurries (2g sediment vs. 20 ml liquid). The sediment was collected in a harbor situated in a high density industrial area, characterized by a great hydrocarbon C>12 and PAHs contamination. The investigated parameters were: the H(2)O(2) dose, the reagents pH and the effect of a phosphate salt and ferrous iron addition. To evaluate sediments characteristics COD, particle size, thermogravimetric and differential thermal analyses were performed under N(2) and O(2) atmosphere while dissolved organic carbon and COD analyses were performed on the filtrate. Results indicate that the treatment was able to change the organic matter to a less hydrophobic state, to destroy part of the organic carbon (up to 78% decrease of the 200-400 degrees C labile organic matter), to lower the COD of the sediment (60% COD removal maximum) and to increase the cumulated distribution undersize. In addition as the treated sediment showed easier-to-handle characteristics, reduced caking and lower aggregation capacity, the modified Fenton treatment could also be considered a pre-treatment of a successive thermal treatment.

Kinetic analysis of biomass pyrolysis using a double distributed activation energy model

Pyrolysis is a fundamental step in thermochemical processes of biomass materials, so a suitable kinetic model is an essential tool to predict the evolution of the resulting products of reaction. However, many difficulties arise in modeling this process step due to the very high number of the involved reactions. In this work, a new double-Gaussian distributed activation energy model was applied in fitting the experimental data of olive residue pyrolysis obtained by thermogravimetric analysis. 2-DAEM formulation considers two sets of parallel reactions occurring and sharing the same pre-exponential factor, but shows different distributions of the activation energy, described by two separate Gaussian distributions that, in turn, grasp the two pyrolysis steps with a high accuracy. Since it is well known that in fitting all the kinetic parameters the pre-exponential factor results highly correlated with the activation energy, the former parameter was separately estimated as a linear combination of the values obtained for the three main biomass components, cellulose, hemicellulose and lignin.

Exoelectrogenic Activity of a Green Microalgae, Chlorella Vulgaris, in a Bio-photovoltaic Cells (bpvs)

Bio-photovoltaic cells (BPVs) are a new photo-bio-electrochemical technology for harnessing solar energy using the photosynthetic activity of autotrophic organisms. This is a new technology for the production of sustainable and “clean” energy.Currently power outputs from BPVs are generally low and suffer from scarce efficiencies. However, a better understanding of the electrochemical interactions between the autotrophic microorganisms and conductive materials will be likely to lead to increased power yields. In the current study, the green microalgae Chlorella vulgaris was investigated for exoelectrogenic activity.To assess the exoelectrogenic activity of C. vulgaris a particular bio-photovoltaic cell was designed and built. The most important element is represented by the electrode configuration, based on inexpensive materials, with the anode immersed in the cultural broth and the cathode exposed to the atmosphere. This configuration represents a very interesting simplification for the cell design, furthermore allowing a simple illumination of the algal culture via a light source positioned above the cell, perpendicular to the electrode surface.This new kind of bioelectrochemical system does not need organic substrate and mediators, and the net production of CO2 is zero.This device was then characterized by measuring the electrical performance of the BPV. A power density of 14 µW/m2 was recorded, revealing interesting potentialities for green unicellular algae fuelled BPVs.

Biological denitrification of high-nitrate wastewaters: A comparison between three electron donors

Wastewaters discharged by several industrial activities, such as synthetic fibers, mineral processing, fertilizers, metal finishing, and ammunitions and explosives industries, have an high-salinity content and are characterized by a very high concentration of nitrates (more than 3 g/L). The treatment of these wastewaters generally deals in an anoxic biological process performed in activated sludge reactors (ASR). Due to the practical absence of an organic component, the treatment involves the addition of an external source of carbon, as electron donor for denitrification reactions. In addition, explosives industries wastewaters are characterized by low pH (2-3), since nitrates are generally discharged as nitric acid, and this induces a further difficulty in reactor operation, due to the extreme sensitivity of denitrifying biomass to pH conditions. In this paper the results of an experimentation performed in a laboratory scale anoxic ASR treating a highnitrate wastewater, simulating the explosives and ammunitions industries wastewaters, are presented and discussed. Three different carbon sources (methanol, acetic acid and sucrose) were compared, and the conditions to achieve the maximum removal of nitrogen were assessed. The ratio C:N to be maintained in the reactor to optimize cell growth and denitrification rate was also investigated.

Tetrachloroethene recovery and hazard reduction of spent powders from dry cleaning process

Dry cleaning facilities using perchloroethylene produce a solid waste consisting of spent filtering powders with a high content of residual perchloroethylene, together with dyes and non-volatile residues. Untreated spent powders, classified as hazardous waste, cannot be disposed in landfill and incineration represents the only viable alternative. In this study, together with a full characterisation of the waste, the removal and recovery of the residual perchloroethylene by means of different heat treatments was investigated. In particular, tests of distillation and stripping with air and steam were carried out, evaluating the effectiveness of the treatments by quantifying the residual perchloroethylene in the samples treated. The results obtained show that the spent filtering powders contained about 25% wt. of perchloroethylene and that the maximum perchloroethylene recovery was obtained by steam stripping; approximately 98% after only 50 minutes. However, this treatment accounted for the production of a liquid mixture containing perchloroethylene and of a solid waste that required a further washing with boiling water to decrease the residual organic content below the eligibility criteria for landfill disposal.