Environmental and energy performances of the Italian municipal solid waste incineration system in a life cycle perspective.

The environmental and energy performances of the Italian municipal solid waste incineration (MSWI) system was investigated by a life cycle assessment approach. On average the 39 MSWIs operating in Italy in 2018 treated about 6,000,000 Mg of residual municipal solid waste (RMSW) recovering on average from 448 kWh Mg-1 RMSW to 762 kWh Mg-1 RMSW of electricity and from 732 kWh Mg-1 RMSW to 1102 kWh Mg-1 RMSW of heat. The average quantity of CO2eq Mg-1 RMSW emitted ranged from about 800 up to about 1000 depending on the size and on the energy recovery scheme of the facility. Avoided impacts (i.e., negative values) were detected for the kg PM2,5eq Mg-1 RMSW and for human health (disability-adjusted life year Mg-1 RMSW). The determination of the hybrid primary energy index (MJ Mg-1 RMSW) indicated that mainly large size facilities and those operating according to a power and heat energy recovery scheme are effectively able to replace other primary energies by the exploitation of the lower heating values of the RMSW.

Environmental and human health impact of different powertrain passenger cars in a life cycle perspective. A focus on health risk and oxidative potential of particulate matter components.

Different powertrains passenger cars, homologate in compliance with Euro 6 standard, were compared in a life cycle perspective for assessing both environmental and human health impacts. For this latter aspect, some correlation between the emission of heavy metals, elemental carbon, organic carbon, the oxidative potential of particulate matter and the adverse effect on human health were also analyzed and discussed. Battery electric vehicle (BEV) showed the lower greenhouse gases emissions, from 0.1 kgCO2eq/km to 0.2 kgCO2eq/km but were charged by the higher emissions of freshwater eutrophication and freshwater ecotoxicity, about 6 × 10-6 kgPeq/km and 4 CTUe/km, respectively. Lower resource depletion was detected for cars powered by internal combustion and hybrid powertrains. Amount of particulate matter (PM) emitted resulted lower for petrol-hybrid electric vehicles (Petrol-HEV), of about 5 × 10-5 kgPM2.5eq/km. BEV were charged by the higher values of human toxicity cancer, from about 2 × 10-5 CTUh/km to about 5 × 10-5 CTUh/km whereas Petrol-HEV were credited by the lower impact on human health (DALY/km). The large contribution to PM emission from all the analyzed cars was from tyre and brake wear. Main PM components were elemental (ElC) and organic carbon (OC) compounds. ElC is also a specific marker of PM emitted from traffic. Both ElC and OC were characterized by a strong correlation with the oxidative potential of PM, indicating a threat for human respiratory tract only marginally decreased by the transition from conventional to electric poweretrains vehicles.

Environmental consequences of the treatment of corn contaminated by aflatoxin B1 with co-digestion and co-composting in a life cycle perspective.

Global environmental performances of anaerobic co-digestion and co-composting of aflatoxin B1 (AFB1) contaminated corn were investigated by a life cycle assessment approach. Anaerobic co-digestion of pig slurry and corn with 25 µgkg-1 ww AFB1 concentration resulted able to generate 627 NLkgVS-1 of biogas with a reduction of the AFB1 concentration in the digestate of 44%. At AFB1 concentration of 100 µg kg-1 ww, the process resulted strongly inhibited with a biogas generation of 122 NLkgVS-1 and AFB1 concentration reduction in the digestate of 25%. Co-composting of 100 µg kg-1 dw AFB1 contaminated corn with other substrates as organic fraction of municipal waste, pig slurry, and other lignin-cellulosic residues showed a removal efficiency of AFB1 ranging from about 80 up to 95% depending on the different mixtures adopted. Environmental consequences associated to the removal of 1 mg of AFB1 in different scenarios investigated, including also the use on land of the digestate and of the compost, indicated that global warming was affected equally by co-digestion and co-composting, about 95 kgCO2eq. Co-digestion showed also the possibility of achieving avoided emissions of about - 0.007 kgNMVOCeq, - 2.5E-3 kgPeq, and - 30CTUe. Benefits concerning resource depletion resulted higher for co-composting due to the high amount of mineral fertilizer replaced. Contribution of AFB1 in the determination of human health (DALY) resulted lower than about 4% for co-digestion and practically negligible for co-composting.

How collection efficiency and legal constraints on digestate management can affect the effectiveness of anaerobic digestion of bio-waste: An analysis of the Italian context in a life cycle perspective.

The influence of collection efficiency and of legal regulations on both the technology and the effectiveness of energy and fertilizer recovery from the anaerobic digestion (AD) of bio-waste was investigated in a life cycle perspective for the Italian context. Concerning collection efficiency, some correlation was detected to both the AD technology and the amount of energy and fertilizer recovered. Nine out of 31 CE plants were based on solid anaerobic digestion batch located in those areas with collection efficiency <65%, recovering about 100 kg and 125 kWh of fertilizer and electricity, respectively, per Mg of bio-waste. The 17 plants adopting wet technologies were implemented in areas with collection efficiency ranging from 50% up to >85% able to recover on average about 130 kg of fertilizer and 275 kWh of electricity per each Mg of bio-waste. Wet AD was also the only adopted for larger size plants from 60,000 Mg/year up to 600,000 Mg/year. Legal constraint on the direct use on land of the digestate caused an average increase of main impacts such as global warming (kgCO2eq), freshwater eutrophication (kgPeq) and human health (DALY) of about 300%. The effect of the quality of the bio-waste returned after the collection showed lower incidence on the overall impacts of about 20%, and mainly limited to global warming (kgCO2eq) and photochemical ozone formation (kgNMVOCeq).

Is the policy of the European Union in waste management sustainable? An assessment of the Italian context.

The sustainability of the waste management system imposed by EU legislation was assessed using the Italian context as a case study by analysing the period from the year 2007 to the year 2016. An integrated sustainability indicator (ISI) based on environmental, social and economic life cycle approach was used. Since the earlier directives the EU waste management policy was strongly oriented to the implementation of the higher levels of the hierarchy, i.e. preparation for reuse and recycling, and a contemporary ban of disposal activities and in particular of landfill. All this was stated in legal quantitative targets to be achieved within a given scheduled time, demonstrated by continuous implementation of a reliable economic, legal and political framework including, among others, penalties, economic support and extended producer responsibility. Noticeable increase of the amount of waste moved to recycling led to a decrease of main environmental burden due to kgCO2eq and kgPeq. The same activity led to avoided impacts detected for both kgPMeq and human health (DALY). A relevant role related to these benefits was also played by the waste to energy sector. Opposite trend was found for the whole average management costs that change from about 146 €/inhabitant in 2007 to about 218 €/inhabitant in 2016. A general decrease of the ISI of about 10% was also detected indicating an increase of the overall sustainability of the system.

A sustainability assessment for use on land or wastewater treatment of the digestate from bio-waste.

The sustainability of use on land or by processing in a wastewater treatment plant of the digestate from bio-waste was investigated. Sustainability was assessed following a triple bottom line approach entailing environmental, social and economic consequences. A methodology for developing an integrated sustainability indicator was also defined. Global warming and acidification were about 40 kgCO2eq/m3 and 0.7 molcH+eq/m3 and 90 kgCO2eq/m3 and 1.1 molcH+eq/m3 for wastewater treatment and use on land, respectively. The impact on human health for use on land was about 3.5 × 10-4 (DALY), six times higher than wastewater treatment but quite negligible when compared to the DALY associated with other diseases in the same area. Costs calculated for wastewater treatment ranged from about 18 €/m3 up to 35 €/m3, about ten times higher than those related to use on land. The integrated sustainability indicator that was developed indicated higher sustainability for use on land and the relevant influence of such finding with respect to the environmental consequences.

Effectiveness of municipal solid waste incinerators in replacing other fuels. A primary energy balance approach for the EU28.

The latest European Union legislation introduced the possibility of considering high efficiency incineration of waste as a recovery operation, that is, to use waste as a means of producing energy and hence able to replace other fuels. This possibility has been further investigated by expanding the boundaries for the mass and energy balance of municipal solid waste incinerators operating in the EU28. An energetic analysis based on a hybrid primary energy (MJ Mg-1) approach was performed also using the cumulative energy demand index. Average results showed a net hybrid primary energy >0 for those municipal solid waste incinerators recovering only electricity, indicating that no primary energies can be replaced. For those operating in combined heat and power mode, an average hybrid primary energy ranging from about -200 MJ Mg-1 to about -4800 MJ Mg-1 was detected for large-size municipal solid waste incineration facilities (>200,000 Mg y-1). The value of hybrid primary energy for medium and small facilities ranged from about +3000 MJ Mg-1 to -4000 MJ Mg-1. Furthermore, in some operating conditions landfill had a lower hybrid primary energy than those of small-size municipal solid waste incinerators. To some degree, these results are not in agreement with the classification of municipal solid waste incinerators based on the energy efficiency formula, particularly for those recovering only electrical energy.

Impact of different schemes for treating landfill leachate.

Different technological schemes for treating the leachate generated by an existing landfill were compared in a life cycle perspective. On-site advanced processes based on reverse osmosis and evaporation were compared to conventional off-site co-treatment with civil sewage in wastewater treatment plant (WWTP). The inventories of the different scenarios were built by both direct observation of existing facilities and by retrieving data from the literature and similar equipment. Particular care was given for evaluating the energetic and chemical needs for operating the on-site advanced treatments. The evaporation system required 40 kW h/m3 of electricity and 18.5 kW h/m3 of heat, whereas reverse osmosis needed only 8.5 kW h/m3 of electricity. On the other hand the amount of liquid concentrate returned by the evaporation system was only about 0.03 m3/m3 instead of about 0.30 m3/m3 returned by reverse osmosis. The evaporation system also consumed the highest amount of chemicals. Life cycle analysis showed that the impact categories most affected by the different options were human toxicity, both non-cancer and cancer, together with freshwater ecotoxicity. The uncertainty analysis highlighted the major contribution associated with direct emissions from the processes. On the basis of mean values, the qualitative trends were substantially confirmed.