ENVIRONMENTAL EVALUATION OF PLASTIC WASTE MANAGEMENT SCENARIOS L. Rigamonti 1, J. Møller 2, M. Grosso 1, T.H.Christensen 2

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1 1st International EIMPack Congress Recycling of Packaging Waste: Considering all the Costs and all the Benefits 29, 30 November Lisbon ENVIRONMENTAL EVALUATION OF PLASTIC WASTE MANAGEMENT SCENARIOS L. Rigamonti 1, J. Møller 2, M. Grosso 1, T.H.Christensen 2 1 Politecnico di Milano, Italy 2 Technical University of Denmark, Denmark

2 Context SEWAS Sustainable European Waste Systems Life cycle assessment of prospective integrated waste management schemes J. Møller, V. Martinez Sanchez, J. Clavreul, K.L. Barahona Ramirez, T.H. Christensen L. Rigamonti, S. Magnani, M. Grosso A project for CEWEP Goal: to provide a technically sound environmental assessment (LCA) of a range of alternative municipal solid waste management systems in Europe to identify the environmentally most beneficiary strategies for future waste management in Europe - the role of incineration with a view to 2020 to quantify the importance of choice of waste treatment technologies with special focus on treatment of the plastic fraction in the waste

3 Goal and methodology The plastic fraction of MSW is specifically addressed in this study, since plastic and its management is one of the most debated issues in current waste management in Europe. There is little doubt that clean fractions of individual types of plastic should be recycled, but how do the benefits of recycling or recovery of mixed and potentially dirty plastic compare with the efforts introduced to collect these fractions is still an open question. Five scenarios of plastic management are modelled The environmental assessment was carried out based on the Life Cycle Assessment (LCA) methodology The functional unit is the management of 1 tonne of plastic waste as present in the gross waste

4 Plastic scenarios In the baseline scenario (P0) the plastic is not source separated at all, which means that it is treated together with the residual waste (RW). In scenarios P1 to P4 a range of potential improvements in plastic management is introduced, and out of the total plastic present in the gross waste, a certain amount is sent to recycling.

5 Plastic scenarios: P0 P0: Plastic is not collected separately, nor it is mechanically sorted from the residual waste The plastic is not source separated at all, which means that it is treated together with the residual waste (RW): - 90% is sent to a Waste-to-Energy plant (WTE) - 10% is sent to a Mechanical-Biological Treatment plant (MBT) producing Refuse Derived Fuel (RDF) which is sent to cement kiln (according to the waste management scheme hypothesized for Western Central Europe) Typical waste composition of Western-Central Europe region was selected, representing Scandinavia, the Benelux, Germany, Northern Italy. MSW produced in this region has a relatively high content of paper and a medium content of organic kitchen waste, while total plastic represents 10% in weight.

6 Plastic scenarios: P1 P0: Plastic is not collected separately P1: Source separation only of bottles at 80% efficiency, leading to an overall plastic collection efficiency of 22%. The bottles are mechanically separated into PET and HDPE and then recycled to PET flakes and HDPE granules

7 Plastic scenarios: P2 P0: Plastic is not collected separately P1: Source separation only of bottles at 80% efficiency P2: Source separation of all plastic (80% efficiency for bottles; 50% efficiency for the other plastic fractions), leading to an overall plastic collection efficiency of about 58%. The fraction is separated into PET, HDPE, a polyolefin fraction and residues (i.e. Plasmix) used as fuel. The material will include impurities, dirt and other items which will end up in the Plasmix. An advanced sorting plant located in Northern Italy was taken as a reference for this scenario.

8 Plastic scenarios: P3 P0: Plastic is not collected separately P1: Source separation only of bottles at 80% efficiency P2: Source separation of all plastic P3: Plastic collection (80% efficiency for bottles; 30% efficiency for the other plastic fractions) in the dry bin together with metals. The overall plastic collection efficiency is 43.5%. Composition of the dry bin (wet weight) Iron 21% Aluminium 6% Plastic 73%

9 Plastic scenarios: P4 P0: Plastic is not collected separately P1: Source separation only of bottles at 80% efficiency P2: Source separation of all plastic P3: Plastic collection in the dry bin together with metals P4: No source separation for plastic, but plastic is mechanically sorted from residual waste prior to incineration. The mechanical separation removes PET and HDPE bottles at high efficiency, which are sent to recycling, and other minor high calorific fluxes sent to energy recovery in cement kilns. RW is pre-treated in a MRF facility located just ahead of the WTE plant, where the focus is on removing high quality plastic by mechanical process units for its subsequent recycling. This scenario is based on a new approach proposed in the Netherlands, starting from the assumption that citizens might be annoyed by a further request of sorting plastic waste at their household.

10 Plastic scenarios Scenario F.U.(0) (kg) Source separation (kg) Plastic in the RW (kg) PET to recycling (kg) HDPE to recycling (kg) Polyolefin mix to recycling (kg) Residues to cement kiln (kg) Residual fraction to WTE (kg) Energy consumption (kwh) (3) P (1) P (1) P (1) P (1) P (2) (0) The functional unit is the management of 1 tonne of plastic waste as present in the gross waste (1) 90% sent to WTE and 10% to MBT with RDF production sent to cement kiln (2) Sent to MRF (3) The energy consumption of the MRFs was assigned exclusively to plastic management (i.e. no allocation was done when the plastic management affected other waste streams)

11 Material Process Secondary material/product Avoided primary material/product PET Recycling* Granules of recycled PET Granules of virgin PET HDPE Recycling* Granules of recycled HDPE Granules of virgin HDPE Polyolefin mix Avoided products We have expanded the system boundaries by crediting the plastic waste management system for energy and material recovery Residues and RDF from the plastic in the RW Plastic in the RW and residual fraction in P4 Recycling* Co-combustion in cement kiln Fuel WTE Flakes of mix of polyolefins used to manufacture products traditionally made of wood that instead could be used to generate energy Electricity and heat SEWAS Project Nome L. Rigamonti relatore heat production from natural gas Coal in cement kiln Electricity by coal and heat by a mix (20% district heating (coal and gas), 14% hard coal, 2% lignite, 8% oil, 42% natural gas, 13% wood) *the technical substitution for PET, HDPE and polyolefin mix is respectively 75.5%, 90%, 60%; the market substitution is respectively 81%, 81% and 50%. Benefits from metal recycling resulting from the overall sorting process in P3 and P4 were not ascribed to plastic recycling (i.e. the system was modelled as if only plastic was treated in the waste management system)

12 Added and avoided impacts We have expanded the system boundaries by crediting the waste management system for energy and material recovery + - In general, LCA applied to waste management systems means: +/- To evaluate environmental impacts (direct and indirect) associated with collection, treatment, recovery and disposal of waste To evaluate avoided impacts associated with the conventional production of materials and energy displaced by those produced in the waste system To compare added and avoided impacts to evaluate the overall environmental performances of the system

13 Impact assessment The analysis was carried out with the LCA-waste-model EASEWASTE (Environmental Assessment of Solid Waste Systems and Technologies) developed by DTU Environment, Technical University of Denmark. The impact assessment was conducted according to the EDIP-method. The emissions are aggregated into the following potential impact categories: global warming, acidification, nutrient enrichment (eutrophication), photo-chemical ozone formation and a number of toxic impact categories including eco-toxicity in water and soil and human toxicity via soil, water and air. The potential impacts were normalized using the person equivalent (PE) by dividing the impacts with the yearly impact by an average person from all activities in life

14 mpe/t mpe/fu Results: Non-toxic impact categories Global Warming Acidification Nutrient Enrichment Photochemical Ozone Formation GW AC NE POF Stratospheric Ozone Depletion OD P0 (plastic sorting = 0% without mechanical sorting) P2 (plastic sorting = 80% bottles and 50% other plastic) P4 (plastic sorting =0% with mechanical sorting) P1 (plastic sorting = 80% bottles) P3 (dry bin) P0 contributed with direct savings for all impact categories but Global Warming, where it represents a net load to the environment, in clear contrast with the other scenarios. On the other hand, P0 performed best of all in Acidification. Scenarios P1 to P4 had better results than P0 for Global Warming and Nutrient Enrichment, but with a different pattern. In Stratospheric Ozone Depletion absolute impacts in milli Person Equivalents are very modest, as well as the variation among scenarios. As a final consideration, none of the examined scenarios emerged as the best option for all non-toxic impact categories. SEWAS Project M. Grosso

15 mpe/t Results: Toxic impact categories HT ET Huge impact savings are observed for all of the scenarios in the categories Ecotoxicity in Water, Human Toxicity via Water and Human Toxicity via Soil. On the contrary, Ecotoxicity in Soil and Human Toxicity via Air had negligible impacts or loads in terms of milli Person Equivalents. Differences among scenarios are generally modest, with the sole exception of Ecotoxicity in Water. Focussing on the latter, which is also the most beneficial category, P1 performed best of all, while P2 to P4 resulted worse than P0. As for the non-toxic impact categories, none of the examined scenarios emerged as the best option for all toxic impact categories. SEWAS Project M. Grosso

16 Results: Contributions to global warming The maximum contributions to the savings on Global Warming impact category are related to plastic co-combustion in cement kiln and plastic recycling. Plastic in the residual waste ending up in RDF co-combusted in cement kiln also plays a role, despite the modest amount of material following that path. Incineration always represents a load due to the fossil CO 2 emissions from plastic combustion. It is then easy to understand why for this impact category the P0 scenarios performs worst, giving a net load to the environment, while all the other scenarios where a certain amount of plastic is recycled or cocombusted result in a net saving. SEWAS Project M. Grosso

17 Results: Contributions to acidification A completely different picture compared to Global Warming is obtained for Acidification, where incineration of plastic contained in the residual waste plays a major role in determining the savings. This is due to the balance of SO 2 emissions between plastic combustion and substituted coal combustion, the latter being much higher because of the higher content of sulphur. Plastic recycling and plastic co-combustion in cement kiln give a modest saving in P1 to P4 scenarios, while in P4 the operation of the MRF for plastic sorting prior to incineration constitutes a load. This is due to its energy consumption which, as explained, in the modelling of the plastic scenarios was fully allocated to the plastic content of the residual waste. SEWAS Project M. Grosso

18 Results: Contributions to nutrient enrichment For Nutrient Enrichment, incineration of plastic in the residual waste is very relevant in determining the overall savings for scenario P0, while for scenarios P1 to P4 it gives savings of similar order of magnitude with plastic recycling. A similar picture was obtained for Photochemical Ozone Formation and Stratospheric Ozone Depletion. SEWAS Project M. Grosso

19 Conclusions (1) When moving from the P0 treatment strategy to the other scenarios, it can be concluded that: Substantial improvements (i.e. transforming loads to savings) can be obtained for Global Warming, especially with the P2-scheme Minor improvements can be obtained for Nutrient Enrichment Impact in the category of Acidification will increase (in terms of a lower saving and not of an actual load to the environment) In the remaining impact categories the changes are relatively small SEWAS Project M. Grosso

20 Conclusions (2) In conclusion, the proposed plastic management strategies performed well since all the improvement scenarios P1 to P4 show net savings for all the impact categories. None of the examined scenarios emerged as the best option for all impact categories: if focus is on Global Warming, the best alternative is scenario P2 (Source separation of all plastic), whereas for the rest of impact categories the best options are P1 (Source separation only of bottles at 80% efficiency) and P4 (No source separation for plastic, but plastic is mechanically sorted from RW prior to incineration). P0 (Plastic is not collected separately) clearly performs best of all only in the Acidification category. SEWAS Project M. Grosso

21 THANK YOU FOR YOUR ATTENTION!