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Report: comparison of environmental impacts from solid waste treatment and disposal facilitiesReleases of pollutants to the environment were determined on the basis of per tonne municipal solid waste (MSW) received for three widely implemented technologies: (1) land®lling with energy recovery; (2) waste to energy; and (3) mechanical separation to refuse-derived fuel (RDF)/compost with RDF incineration for energy recovery. All three technologies were considered with a nominal capacity of 1000 tonnes MSW per day. The analysis was based on the solid waste composition of Athens, Greece, and the facilities were assumed to meet EU Directives and to include the proper disposal of residues. It was found that land®lling with energy recovery produces slightly higher air pollution and greenhouse gas releases, mainly owing to the emission of uncollected biogas. Released leachate rates are at a ratio of 5:1:2 for land®lling with energy recovery, waste to energy and mechanical separation to RDF/compost with RDF incineration for energy recovery, respectively. Land®lling with energy recovery does not produce air emissions of toxic metals, but releases dioxins and furans at the same levels as the other two methods; polychlorinated biphenyls are also released by land®lling with energy recovery, mainly due to electricity production from biogas. Mechanical separation to RDF/compost with RDF incineration for energy recovery produces lower releases per tonne MSW for most pollutants, but the pollutants are more widely dispersed in soils, groundwater and the atmosphere. The methodology used is not signi®cantly affected by uncertainties and may be used for the further evaluation of environmental impacts and the assessment of integrated MSW management schemes.

Variations in waste quantities and composition affect incinerator operating conditions and performance. Fluegas volumes consititute a dominant environmental and financial consideration for efficient waste incinerator (WI) operation, since they affect the temperature, throughput, air pollution control system (APCS) residence time, and pollutant emissions, when the charging rate or composition of any waste is varying. Fluegas recirculation (FGR) in WI is an effective technique for reducing WI atmospheric pollution, mainly NOx emissions, albeit affecting WI throughput, temperature and destruction/removal efficiency. FGR refers to mass recirculation of a possibly cooled fraction of fluegases and differs substantially from fluegas heat recovery. The present work shows that, besides emission control, suitable manipulation of FGR enhances WI performance under waste uncertainty, enabling higher throughput, at the desired temperature and within the allowed APCS residence time range. A dimensionless parameter related to the uncertain wastes' net enthalpy contribution is isolated, which encompasses heat of reaction and enthalpy outflows from fluegas and solids and which reveals whether throughput is decreasing or increasing with temperature and FGR ratio. Normalized throughput and total fluegas volume isotherms manifest the interdependence and enable manipulation for enhanced environmental and economic performance.

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