Vincenzo Riganti

Fe2O3 addition effects on the NiMgO gasification catalyst

Abstract Crystallographic techniques were used to study the effects produced by the addition of Fe 2 O 3 to the NiMgO gasification catalyst, and to understand the reasons for the anomalous behavior of some catalysts. X-Ray diffraction gave a valuable contribution to the knowledge of the phenomena occurring during catalyst life, and enabled a check on the existence of interactions between the active metal (Ni) and the metal of the protective oxide (Fe 2 O 3 ), and a follow up of the course of these reactions in the solid state. These reactions give dispersed Fe-Ni alloys, with little catalytic activity, thus explaining the activity change of the catalyst after a period of use.

REUSE OF STABILIZED WASTE AS CONSTRUCTION MATERIALS

Abstract This study aimed to asses the feasibility of concrete production using stabilized waste as an addition to natural aggregates. Two inorganic waste streams were considered: foundry residues and fly ashes from municipal solid waste incineration. They were treated by means of a commercial cement-based stabilization/solidification process (using cement, lime and sodium silicate). After several days of curing, they were dried, milled, and sieved before being used as fine aggregate for concrete production. Produced concrete was then subjected to conventional physical-mechanical testing procedures (compression, traction, flexure, modulus of elasticity, shrinkage). In samples containing 200 kg waste/m3 concrete, a very high compressive strength was achieved after 28 days curing time. Besides, leaching behavior of the concrete was evaluated, by means of different kinds of leaching tests. Experimental results showed a remarkable reduction of metal leaching of concrete with respect to stabilized waste. In some cases (foundry residues), the same behavior was observed in “natural” concrete (produced with natural aggregates) and “waste containing” concrete.

DRINKING WATER AND WASTE WATER DISINFECTION: STRATEGIES AND PROBLEMS

Abstract Within the European Union, many different disinfection systems are being used. They are applied both in facilities for the potabilization of ground and surface water, and for the disinfection of wastewater after a biological treatment. Although chemical and physical processes are usually employed, treatment procedures and results are quite different. In this work, main disinfection systems used in European Countries in water potabilization facilities are described. The growing use of surface water for the production of drinking water, underlines the necessity to minimize the formation of by-products with potentially toxic long-term effect. This leads to define adequate control strategies in potabilization processes: both used reagents and process schemes must be analysed considering this important aspect. In the second part of the paper, problems dealing with the disinfection of wastewater and the main characteristics of the most important disinfection systems (as far as their applicability and efficiency are concerned) are analyzed. The results of a research carried out in order to compare four different disinfection systems (ozonation, disinfection with chlorine dioxide, UV radiation, peracetic acid disinfection) are also shortly presented.