I. Noya 1, S. González-García 1, G. Feijoo 1, E. Katsou 2, V. Inglezakis 3, M.T. Moreira 1

Transcription

1 I. Noya 1, S. González-García 1, G. Feijoo 1, E. Katsou 2, V. Inglezakis 3, M.T. Moreira 1 1 Department of Chemical Engineering, University of Santiago de Compostela, Santiago de Compostela, Spain 2 Department of Mechanical, Aerospace and Civil Engineering, Brunel University London, Uxbridge, UK 3 Chemical Engineering Department, Nazarbayev University, Astana, Kazakhstan Sara.gonzalez@usc.es 5 th International Conference on Sustainable Solid Waste Management Athens, June 2017

2 ASTANA KAZAKHSTAN Population 872,619 inhabitants Population density 7 inh/km 2 Municipal Solid Waste (MSW) generation 1,118 t/day ( 1.3 kg/inh/day)

3 1, Waste generation (t/d) Waste collection (t/d) Collection capacity (%) MECHANICAL TREATMENT (MT) PLANT S0 materials Table 1. Average MSW composition in Astana. MSW fraction Composition (%) LLECTION MT PLANT LANDFILL Organic waste 27.6 Plastics 15.5 Glass 14.9 LANDFILLING S1 Paper/Cardboard 11.2 Green waste (garden) 2.80 Mechanical separation is prioritised instead of landfilling practices Metals 0.95 Wood 0.60 LLECTION LANDFILL

4 MT PLANT + 50% BIOGAS VALORISATION S2 materials Biogas LLECTION MT PLANT LANDFILL MT PLANT + 100% BIOGAS VALORISATION S3 materials Biogas LLECTION MT PLANT LANDFILL

5 ENVIRONMENTAL PERFORMANCE Current practices in Astana (S0) Base case LANDFILLING (S1) MB PLANT + 50% BIOGAS VALORISATION (S2) MB PLANT + 100% BIOGAS VALORISATION (S3)

6 INPUTS Table 2. Average annual inventory data for the different scenarios. Inputs/Outputs S0 S1 S2 S3 Inputs MSW flow (t) MSW flow Electricity consumption Land use Transport activities Electricity (kwh) Land use (ha) OUTPUTS PRODUCTS Transport (t km) Outputs Products Electricity (kwh) Heat (kwh) Paper/Cardboard (kg) Renewable electricity Renewable heat EMISSIONS materials Plastics (kg) Glass (kg) Metals (kg) Outputs Emissions Diffuse emissions (t) (kg)

7 Impact Categories Acronyms Units Definition Climate Change CC kg 2 eq Emissions of greenhouse gases to air. Terrestrial Acidification TA kg SO 2 eq Acidifying effect of acidifying substances (SO 2, NO x, NH 3 ) Freshwater Eutrophication FE kg P eq Marine Eutrophication ME kg N eq Table 3. Definition of impact categories evaluated. Impacts from environmental persistence (fate) of the emission of P containing nutrients. Impacts from environmental persistence (fate) of the emission of N containing nutrients. Land use LU m 2 Land occupied for a certain time. Fossil Depletion FD kg oil eq Extraction of fossil resources. Method: ReCiPe Midpoint (H) FU: 1 ton MSW treated Scope: cradle to grave System expansion approach: Avoided fossil energy generation Avoided materials production

8 Relative contributions 100% 80% 60% 40% 20% 0% 20% 40% GHGs emissions Electricity requirements Plastics 60% 80% 100% CC TA FE ME LU FD kg 2 eq kg SO2 eq kg P eq kg N eq m2 kg oil eq Paper/ Cardboard Diffuse emissions Energy use Transportation Paper/cardboard Glass Metals Plastics

9 Table 3. Comparative environmental results (FU: 1 ton MSW treated). Impact category Units S0 S1 S2 S3 Climate Change kg 2 eq Terrestrial Acidification kg SO 2 eq Freshwater Eutrophication kg P eq Marine Eutrophication kg N eq Land Use m Fossil Depletion kg oil eq Similar results (except for S1) can be found in LU; recovered materials have the greatest influence, instead of renewable energy generation. Relative relations (%) CC TA FE ME LU FD S0 MT Plant S1 Landfilling S2 MT + 50% Biogas Valorisation S3 MT + 100% Biogas Valorisation

10 Energy use is the main contributor to the environmental impacts for MT plant (S0, base case), together with the GHGs emissions; Conversely, the recovery of recyclable materials have a really beneficial effect on most impact categories. Those scenarios where the generation of renewable energy from biogas combustion is prioritised show the best environmental performances in most of impact categories. The higher the biogas valorisation, the most environmental friendly results. Related land use impacts are strongly dependent on the environmental credits derived from paper and cardboard recovery.

11 Questions