Environmental Impact Assessment Of A MSW Incinerator

This paper presents a study of the emission impact of a Municipal Solid Waste Incinerator located in a predominately agricultural and residential valley but containing some industrial sites. The MSWI “Pace” has been operating since 1979 treating about 100 tons per day of municipal solid waste and it is equipped with flue gas emission treatment and monitoring systems. Its impact on the territory is exclusively due to gas emission into the atmosphere because it is equipped with a closed water cycle and a good slag disposal system. Recently great attention has been paid to the study of the environmental impact of industrial activities in particular for waste treatment plants. The construction of new plants for waste treatment and disposal or the maintenance of the older ones have become a critical issue. Nevertheless these installations are essential to complete the waste management cycle with the recovery of materials and/or energy. However, a MSWI could also be a possible source of environmental pollution. Human exposure to chemicals can occur directly through contact and inhalation or indirectly through the consumption of food or water contaminated by airborne pollutants. In the last twenty years European Directives have first suggested and then suddenly imposed laws and regulations for the reduction of environmental pollution produced by industrial activities. Today, an integrated approach to environmental problems is becoming common in order to manage pollution in compliance with the new European obligations. The main environmental and health impacts of a MSWI are connected with the stack gas emissions and solid residues (fly ash, heavy ash, slag) due to the waste combustion processes. In order to maintain the pollutants emissions under the threshold limits it is necessary the control of the gas treatment system and the following combustion parameters: the waste feeding, flame contact time, air injection, smoke temperatures in each section, heat recovery, the inclusion and management of the post-combustion chamber, etc. Persistent organic pollutants (POPs) are mainly PCCDs, PCDFs, PCBs, the hexachlorobenzene and various organochlorine pesticides. More recent researches have been focused on the study of these substances which can be considered the most dangerous due of their characteristics (toxicity, low biodegradability and high accumulation tendency for the environment and human organism). During these last years, a large number of studies show an increase of the levels of micropolluting in terrain, vegetables and human organisms, such as PCDD/PCDF, PCB, heavy metals and others “biomarkers”. So it is important to quantify the increase of pollutants due to the presence of MSWI. The MSWI “Pace” is equipped with adequate instrumentation to analyse gas emissions. Some parameters are continuously monitored such as temperature, humidity, HCl, O2, CO, volumetric mass flow, pressure, powders, SOx and NOx. Other parameters and substances emitted are measured every four months with the competent authorities. The objective of this work has been, starting from the statistical analysis of the incinerator emissions, to obtain a number of maps showing the impact of the polluting substances. To assess the MSWI impact on the area, various simulations have been performed, taking into account both the emission source detailed monitored data and territorial properties. The simulations of atmospheric transport and deposition of the substances emitted from the chimney have been made with the analytical stationary AERMOD code developed by the EPA of the USA. It is based on the Gaussian approach. The code application allowed the local atmospheric conditions simulations and the estimation of the chemical dispersion and deposition. Results show in iso-concentration and iso-deposition curves calculated, it is possible to observe that higher concentrations are reached inside the valley where the chimney is located. The top of the chimney i..