Tools for evaluation of impact associated with MSW incineration: LCA and integrated environmental monitoring system

The identification of significant pollutants emitted from the contamination source is the first step in evaluating the impact associated with anthropic activity. Municipal solid waste (MSW) incinerators are still generally perceived as great pollutant sources, in particular due to their gaseous emissions from the stack, which constitute the major effluent from the plant. In this work a life cycle assessment and an integrated environmental monitoring system were applied together, in order to obtain complete information about the incineration process and its environmental impact. The former is a proven methodology, but its application to waste management systems constitutes a relatively new field of application with a great developmental potential. The contribution of the incineration process to the different environmental impact categories was investigated, finding many avoided impacts due to energy recovery. The latter is an innovative approach that allows a remarkable understanding of impact due to a contamination source; interesting correlations were found between heavy metals both in gas emissions and in natural matrices in the surroundings.     

Volatile organic compounds produced during the aerobic biological processing of municipal solid waste in a pilot plant

The volatile organic carbon (VOC) and odours emitted during the aerobic biological processing of municipal solid waste (MSW) was studied in a pilot-scale reactor. VOCs were detected by different techniques on solid waste samples and the outlet air stream, before and after a biofilter. Organic compounds (alpha-pinene, beta-myrcene, D-limonene) were also measured in condensate water and leachate from the process. Results showed uniformity in the composition of the air in the solid waste samples, air sampled during the process and condensed water, indicating a matrix-derived origin of these compounds. Leachates, however, contained substances with a quite different molecular structure from the compounds identified in the gaseous fraction. Most of the substances in the gaseous effluent had a hydrocarbon-like structure, mainly terpenoids. The odour produced and detected through olfactometry agreed with GC-MS analyses. This was true above all for terpenes.     

Long-term effect of sewage sludge application on soil humic acids

Sewage sludges are used in agriculture because they act as a fertilizer. Long-term studies are needed to evaluate the effect of sewage sludge on soil properties by paying particular attention to the soil organic matter. Soil plots were amended for 10 years with 1Mg dry matter ha(-1)year(-1) of sewage sludge. Chemical parameters such as total organic carbon (TOC), N, C/N ratio and CEC were determined when this period ended. Moreover, TOC was fractionated into humified and non-humified fractions. Humic acids (HA) were isolated and studied by elemental analysis, DRIFT, (1)H NMR and CPMAS 13C NMR spectroscopies. At the end of the tests, compared to the control soil, the sludge-amended soil did not exhibit change in total organic C and related humified fractions. However, the HA composition of the soil treated with sludge had developed an HA composition closer to that of the HA-sludge as a result of the enrichment of recalcitrant fractions contained in the sludge.     

Spray-dry desulfurization of flue gas from heavy oil combustion

An experimental investigation on sulfur dioxide removal in a pilot-scale spray dryer from the flue gas generated by combustion of low-sulfur (S) heavy oil is reported. A limewater slurry was sprayed through an ultrasonic two-fluid atomizer in the spray-dry chamber, and the spent sorbent was collected downstream in a pulse-jet baghouse together with fly ash. Flue gas was sampled at different points to measure the desulfurization efficiency after both the spray-dry chamber and the baghouse. Parametric tests were performed to study the effect of the following variables: gas inlet temperature, difference between gas outlet temperature and adiabatic saturation temperature, lime-to-S ratio, and average size of lime particles in the slurry. Results indicated that spray drying is an effective technology for the desulfurization of low-S fuel oil flue gas, provided operating conditions are chosen carefully. In particular, the lowest gas inlet and outlet temperatures compatible with baghouse operation should be selected, as should a sufficiently high lime-to-S ratio. The attainment of a small lime particle size in the slurry is critical for obtaining a high desulfurization efficiency. A previously presented spray-dry flue gas desulfurization model was used to simulate the pilot-scale desulfurization tests, to check the ability of the model to predict the S capture data and its usefulness as a design tool, minimizing the need for pilot-scale experimentation. Comparison between model and experimental results was fairly good for the whole range of calcium/S ratios considered.     

Lichen biomonitoring of trace metals in the Pistoia area (central northern Italy)

The epiphytic lichen Parmelia caperata (L.) Ach. was used as bioaccumulator of the heavy metals Cd, Cr, Cu, Hg, Ni, Pb and Zn in the environs of the town of Pistoia (central northern Italy). The concentrations of Cd, Cr, Ni, Hg and Pb were comparable with those found in areas not subject to atmospheric pollution. Copper and especially Zn were found in rather high concentrations. Fertilizers and pesticides were the main source of atmospheric contamination.     

Source apportionment and location by selective wind sampling and Positive Matrix Factorization

In order to determine the pollution sources in a suburban area and identify the main direction of their origin, PM_2.5 was collected with samplers coupled with a wind select sensor and then subjected to Positive Matrix Factorization (PMF) analysis. In each sample, soluble ions, organic carbon, elemental carbon, levoglucosan, metals, and Polycyclic Aromatic Hydrocarbons (PAHs) were determined. PMF results identified six main sources affecting the area: natural gas home appliances, motor vehicles, regional transport, biomass combustion, manufacturing activities, and secondary aerosol. The connection of factor temporal trends with other parameters (i.e., temperature, PM_2.5 concentration, and photochemical processes) confirms factor attributions. PMF analysis indicated that the main source of PM_2.5 in the area is secondary aerosol. This should be mainly due to regional contributions, owing to both the secondary nature of the source itself and the higher concentration registered in inland air masses. The motor vehicle emission source contribution is also important. This source likely has a prevalent local origin. The most toxic determined components, i.e., PAHs, Cd, Pb, and Ni, are mainly due to vehicular traffic. Even if this is not the main source in the study area, it is the one of greatest concern. The application of PMF analysis to PM_2.5 collected with this new sampling technique made it possible to obtain more detailed results on the sources affecting the area compared to a classical PMF analysis.     

Food web of a confined and anthropogenically affected coastal basin (the Mar Piccolo of Taranto) revealed by carbon and nitrogen stable isotopes analyses

Carbon and nitrogen stable isotope analysis was used to examine the food web of the Mar Piccolo of Taranto, a coastal basin experiencing several anthropogenic impacts. Main food sources (algal detritus, seaweeds, particulate organic matter (POM) and sediment organic matter (SOM)) and benthic and pelagic consumers were collected during two contrasting seasons (June and April), at four sites distributed over two inlets, and characterized by different level of confinements, anthropogenic inputs and the presence of mussels farming. δ¹³C values of organic sources revealed an important contribution of POM to both planktonic and benthic pathways, as well as the influence of terrigenous inputs within both inlets, probably due to high seasonal land runoff. Although δ¹³C of both sources and consumers varied little between sampling sites and dates, δ¹⁵N spatial variability was higher and clearly reflected the organic enrichment in the second inlet as well as the uptake of anthropogenically derived material by benthic consumers. On the other hand, within the first inlet, the isotopic composition of consumers did not change in response to chemical contamination. However, the impact of polluted sediments near the Navy Arsenal in the first inlet was detectable at the level of the macrobenthic trophic structure, showing high dominance of motile, upper level consumers capable to face transient conditions and the reduction of the more resident deposit feeders. We therefore underline the great potential of matching stable isotope analysis with quantitative studies of community structure to assess the effects of multiple anthropogenic stressors.     

Use of agro-industrial organic sludge amendment to remediate degraded soil: chemical and eco(geno)toxicological differences between fresh and stabilized sludge and establishment of application rates

Soil degraded by coal mining activities can be remediated by amendment with agro-industrial organic sludge. However, the environmental impacts associated with this management practice must be properly addressed. In this context, the objective of this study was to evaluate the eco(geno)toxicity of a fresh and a stabilized sludge before use in a laboratory soil remediation test. Chemical analysis of the complex mixtures (degraded soil, fresh sludge, and stabilized sludge) was carried out, as well as a battery of eco(geno)toxicity tests on microbiological enzymes (fluorescein hydrolysis), earthworms, and higher plants (including Vicia faba genotoxicity test), according to published methodologies. The results of these tests showed that fresh sludge was more toxic than sludge stabilized over 6 months toward earthworms and higher plants (lettuce, corn, and wild cabbage), while phyto(geno)toxicity tests with V. faba indicated the same genotoxicity levels for the two types of sludge. In the soil remediation simulation using different mixtures of degraded soil and stabilized sludge, the proportions of 50:50 % (dry weight basis) provided the lowest phyto(geno)toxicity effects and this mixture can be used for the revegetation of the contaminated site.     

End-of-Life Vehicles management: Italian material and energy recovery efficiency

Each European Member State must comply with Directive 2000/53/EC recycling and recovery targets by 2015, set to 85% and 95%, respectively. This paper reports a shredder campaign trial developed and performed in Italy at the beginning of 2008. It turns out to be the first assessment about the critical aspects belonging to the Italian End-of-Life Vehicles (ELVs) reverse supply chain involving 18 dismantling plants, a shredder plant and 630 ELV representatives of different categories of vehicles treated in Italy during 2006. This trial aims at improving the experimental knowledge related to ELVs added waste, pre-treatment, part reuse, recycling and final metal separation and car fluff disposal. Finally, the study also focuses on the calculation of the effective Italian ELV recycling rate, which results equal to 80.8%, and auto shredder residue (ASR) characterization. According to the results obtained in this work, ASR still contains up to 8% of metals and 40% of polymers that could be recovered. Moreover, physical-chemical analysis showed a Lower Heat Value of almost 20,000 kJ/kg and revealed the presence of pollutants such as heavy metals, mineral oils, PCBs and hydrocarbons.     

Indicators of waste management efficiency related to different territorial conditions

The amount of waste produced and the control of separate collection are crucial issues for the planning of a territorial Integrated Waste Management System, enabling the allocation of each sorted waste fraction to the proper treatment and recycling processes. The present study focuses on assessing indicators of different waste management systems in areas characterized by different territorial conditions. The investigated case study concerns the municipalities of Emilia Romagna (northern Italy), which present a rather uniform socioeconomic situation, but a variety of geographic, urban and waste management characteristics. A survey of waste generation and collection rates was carried out, and correlated with the different territorial conditions, classifying the municipalities according to altitude and population density. The best environmental performances, in terms of high separate collection rate, were found on average in rural areas in the plain, while the lowest waste generation was associated with rural hill towns.