In agreement with the new European Union directives concerning the valorization of materials and energy recovery, Municipal Solid Waste (MSW) management is, in general based on an integrated approach characterized by a combination of different treatment processes. The bio-mechanical treatment (BMT) of MSW is an increasing option in Europe either as a pre-treatment before landfilling or as a pre-treatment before combustion. In this context the research on the bio-drying process is not fully developed. In the present paper the Lower Heating Value (LHV) dynamics during MSW bio-drying has been assessed. Measurements were made using a pilot scale bio-dryer that allows the recording of data as air flow, temperature (at the entrance, at the exit and inside the waste), and weight loss. An initial characterization of the MSW completes the input data. Results give information on the dynamics of the main process parameters (humidity, volatile solids, ammonia, Lower Heating Value) and also of additional parameters.

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The acceleration of urbanization phenomena in many countries increases the generation of municipal solid waste. One of the biggest problems that Romania encountered before and after the entrance in the European Union is the waste management related to an increasing generation and the necessity to comply with the European directives. An important requirement regards the reduction of the amounts of landfilled biodegradable material. Where landfilling is widely used, the most serious environmental problems, both for Romania and for the other countries, are connected to the biogas and leachate production in the landfill and the related pollution. The present paper wants to study some options (pressing, anaerobic digestion, bio-stabilization) for the treatment of municipal solid waste before landfilling in sanitary landfills. Data regarding mass, volume, energy and environmental balances are presented. Taking into account the local requirements additional scenarios can be analyzed in order to increase/modify the information available for the decision makers.

In the field of Municipal Solid Waste (MSW) management, dewatering before combustion is adopted in particular cases. The aim is the modification of the waste characteristics in order to increase its LHV and allow an easier removal of glass, metals and other inert material. The process is named bio-drying when it is based on biological aerobic reactions; no auxiliary fuel is needed thanks to the exothermic reactions that develop under aerobic conditions. About 2.5 million t MSW /y will be bio-dried in 2006 when all the bio-drying plants under construction will be completed. When the process is based on an external supply of heat (generally obtained from auxiliary fuel), the option is named thermal drying. This is well developed for sewage sludge but less for MSW. In Italy we can find a few experiences of thermal drying on the oversieve from MSW automatic sorting. In this case the aim is the decrease of humidity for the production of Refuse Derived Fuel (RDF) as, according to the Italian regulation, the highest value of humidity for RDF is 25%. A few proposals of thermal drying have been proposed as a pre-treatment before combustion in two Italian towns where an incinerator has been planned. In both cases the proposal is integrated with the combustor (in order to use a part of the heat of the off-gases) and the aim is the preparation of the waste to an easier inert, glass and metals removal (for material recycling and for decreasing the impact of the incineration). The present paper shows a comparison between bio-drying and thermal drying taking into account MSW characteristics, environmental aspects, energy balances and costs. An additional comparison concerns the role of selective collection of biodegradable fraction in order to decrease the humidity of the residual MSW.