Lca for Waste Management by kvc26933

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									        Case studies for LCA application in waste management and recycling
       Paolo Masoni, Grazia Barberio, Roberto Buonamici, Roberto Pergreffi, Simona Scalbi, Federica Tommasi

                                                        ENEA
                                  Via Martiri di Monte Sole 4, 420129, Bologna (Italy)

                                             paolo.masoni@bologna.enea.it

                                 Keywords: LCA, waste recycling, system boundaries

                                                       ABSTRACT
An important application of Life Cycle Assessment (LCA) in the waste sector is the comparison of different scenarios
of products end-of-life. The studies developed in the “Laboratory of LCA and Ecodesign” of ENEA are finalized to the
promotion of re-use, recycling and recovery through the comparison of different processes and innovative technologies.
In particular three case studies, all developed in cooperation with the technologies’developers, are here presented:
1) recycling of polypropylene from packaging boxes: comparison of present situation of closed loop recycling with the
production of pavement blocks;
2) treatment of bottom ashes from municipal waste incineration plant: comparison of landfill (present situation) with i)
production of ceramic glaze and ii) concrete with a percentage of bottom ashes.
3) treatment of polishing sludge produced in the tile industrial district: comparison of landfill (present situation) with
innovative recovering into building materials industry.
All the three case studies have common methodological problems, in particular related to the definition of system and
time boundaries and to transport issues.

Introduction
The assessment of the environmental impacts (as first approach to a more complete sustainability assessment) of life
cycle of innovative processes and technologies at a very early stage is a preventive approach finalized to supply relevant
information to the decision makers. The waste treatment concerns an end-of-life management as well as valorisation in
order to obtain profitable products. There are different possibilities to valorise a waste: innovative technology,
recycling, re-use, energetic recovery. Each different opportunity should be evaluated from an environmental, energetic
and economic view point. Life Cycle Assessment (LCA), avoiding burden shifting, is the most suitable tool for the
sustainability evaluation. But waste treatment scenario are not simple to be modelized. They very often require the
solution of complex methodologic aspects, related with the both spatial and time aspects, together with market
mechanisms.
ENEA has recently constituted an “LCA and Ecodesign Laboratory”, with the purpose to develop methods, tools and
applications for the environmental assessment of systems. This paper deals with three case studies performed in the
framework of the project LITCAR “Technologies and Control of the waste life cycle”, funded by Regione Emilia-
Romagna.

Aim of the studies
In the LITCAR project, “LCA and Ecodesign Laboratory” of ENEA is applying the LCA in two contexts:
   • Evaluation and comparison between different waste integrated management solutions to indicate the best one into
      a industrial regional context characterized by SMEs and districts.
   • Valorisation of waste, as alternative to the landfill disposal, through the manufacturing of products already present
      in the market;
The first context concerns the recycling of polypropylene from disused packaging boxes in the Reggio-Emilia province.
If, until now, all disused boxes were recycled in new boxes for fruit and vegetable market, with the current project you
suggest to produce the pavement blocks using polypropylene in place of cement.
The second context concerns two different studies: the valorisation of bottom ashes to produce ceramic glaze and
concrete and the re-use of sludge derived from the polishing of fine stoneware tiles in bricks. These treatments are a
more safety alternative than the landfill disposal, because wastes are made inert and the release of pollutants is avoided.
Furthermore the sludge is recovered in the same industrial district so potential environmental is reduced both avoid
product and optimisation transport.

Case studies
Recycling of polypropylene from packaging boxes. Every year, in Reggio Emilia’s province, approximately 600 tonnes
of polypropylene packaging boxes used in the fruit and vegetable market are discarded and separately collected by the
multiutility ENIA. The collected plastic boxes are sent at a Modena’s enterprise to obtain re-granulated polypropylene.
Until now, this polypropylene was transported at a distance of 145km and, there, it was recycled in new boxes for the
same market.
An alternative scenario has been proposed by FORTEC s.r.l. in co-operation with Reggio Emilia’s provincial
administration, Correggio’s municipality and Enia. The idea is to use the recycled polypropylene to produce pavement
blocks for external parking. A very important aspect of the proposed scenario is the localisation of the whole chain:
collection, processing and manufacturing processes and the use of the new product would be sited in only one industrial
area, unlike the present scenario. In this context, FORTEC s.r.l. and University of Modena are testing the mechanical
and physic characteristics of a prototype through compression, bending and fatigue test. At this stage of the research,
the block is composed by 20-30% virgin polypropylene, 40-60% recycled polypropylene and 20-30% talc and the
esteemed weight is 1,3kg. The industrial production of blocks with recycled polypropylene is going to substitute an
other product in this moment on the market: the cement block.
From a methodological view point, a correct LCA approach implies the system boundary expansion to assess the best
scenario between two options of polypropylene recycling. Transport environmental impacts between two scenario are
completely different.

Bottom ashes
The Bottom Ashes is the most significant waste resulting from municipal solid waste incineration. Indeed it represents
the 20-30% in mass and it is composed by oxides, especially SiO2, CaO and metal oxides. At the moment, in Italy the
bottom ashes are disposed mainly in landfill [1]. This LCA study concerns the comparison of three scenarios: a
“business as usual” with the landfill disposal and two “alternative” scenarios in which the bottom ashes are valorised as
raw material in products: i) concrete, in substitution of natural aggregates (sand and gravel) and ii) as glass frit useful
for ceramic glaze in substitution of commercial frits.
The aim of the LCA study is the identification of the best solution, from an environmental view point, for bottom ashes
treatment. In accordance with the goal of the study, the boundaries of all scenarios are “from gate to grave”: the
production of bottom ashes from municipal solid waste incineration has not considered because common to all the
studies. The time boundaries are extended to 100 years, in order to include the largest part of the landfill emissions. The
time boundaries for landfill disposal scenario consider three time steps: the active phase (16 years), the landfill
monitoring after the closure (30 years in line with the Italian regional legislation) and the remaining 54 years in which
the landfill is closed, not monitored but when some, decreasing emissions still occur.
In the first time step, the following processes are included:
     • the bottom ashes transport from the incinerator plant to landfill;
     • the input from nature and the emissions connected to construction of landfill;
     • the raw material, energy and fuel consumptions for the operation of the landfill;
In both the first and second periods we have considered:
     • the collected leachate treatment in a wastewater plant,
     • the sewage and water emissions due to leachate treatment in wastewater plant;
     • leachate dispersed in environment, if it is present;
finally, for the last time step, the leachate emissions are considered dispersed in the environment.
The ceramic glaze scenarios include the transport of bottom ashes from municipal solid waste incineration to the firm
producing the glass frit. That is produced with 100% of bottom ashes by a simple and short treatment at relatively low
temperature [2].. The glass frit is utilized in the composition of a ceramic glaze, in a percentage about of 30% in mass.
Credits for the avoided production of commercial frits are included.
The last scenario, concrete, includes transport of bottom ashes from municipal solid waste incineration to the firm for
the pre-treatment, where the bottom ashes are grinded and metals, as aluminium, iron and steel, are separate and
recovered. The energy, raw and auxiliary materials and emission of pre-treatment are included and the transport to the
firm producing concrete as well. In concrete production 30% of bottom ashes pre-treated replace aggregate materials as
gravel and sand. Credits for the avoided use of raw material for the concrete production are included.

Sludge
In ceramic industry are produced high amounts of processing wastes as polishing sludge. In Reggio Emilia and Modena
provinces there is a production of 20,000 tonnes per year of dried sludge. At the moment these wastes are disposed in
controlled landfill for non hazardous waste, according with the Italian regulations but an alternative solution has to be
find in order to tackle environmental and economic problems.
These sludge contains small particles of SiC and Magnesium oxichloride (MgOHCl), cement removed from grinding
stones, and small amounts of material abraded from the tiles. The presence of alkaline oxides and their compounds
doesn’t permit the reintroduction of such waste into the porcelain tile body. The LITCAR project is studying the re-use
of polishing sludge into the brick industry. In the last years was spread the utilization of mixture between clay and
industrial or municipal waste to produce bricks.[6] The analyses of the polishing sludge shows that they can be useful as
a component in brick manufacturing, with a large industrial market and a firing cycle different from ceramic one. Bricks
made with different percentages of the considered waste are tested and analysed in their physical-chemical, mechanical
and structural properties. The results highlight that the addition of waste (max 20% wt) does not change negatively the
main technological properties measured (adsorption, linear shrinkage, effloresce). After the laboratory tests, semi-
industrial experiment is in progress in order to obtain data (mass and energy balance of the process, emissions data) at
an industrial scale, necessary to compile the inventory for the LCA study. The polishing sludge is collected from the
Modena province and it processed in a local enterprise that produces bricks. The use of sludge into mixture gives
several advantages:
•         avoiding the landfill disposal of these wastes;
•         reducing of raw material (clay and water) used in the process;
•         storing process materials at low-price.

      Boundary of landfill disposal                              Boundary of brick manufacturing

    Input data         Polishing Sludge          Output data         Input data      Polishing Sludge         Output data


   Land                              T
   occupation                                                     Land                           T
                                                 Emissions        occupation
   Energy, fuels                                 (dispersed
                            Landfill:             leachate        Energy, Fuel                                  Emissions
   Clay, HDPE,                                                    oil, Natural
                                                     and                               Brick Industry          (NOx, PM10,
   water,                                                         gas
                                                  leachate                                                       SO2, F-)
   concrete
                                                 after 30 y)
                                                                  Machineries
   Machineries                                                                                    T
                                                                  Clay
                        Collected Leachate
                      (years of active phase+
                     30 years of post-closure)                                               Brick
                                                                                        utilization in
                                     T                                                    building
   raw materials,
   chemicals,
                          Wastewater                                                              T
   water                                         Emissions
                           treatment              in water
   Energy, fuels                                                 raw materials,                                Emissions
                                                                                          End Life:
                                                                 water, energy,                                 in soil, air
                                                                 fuels                Brick to disposal        and water
                       End Life - sewage:
                    •Incineration
                    •Sprinkling in agriculture                            Avoid products: brick manufacturing
                                                                          by traditional process



    Figure1: Boundary of disposal landfill and brick manufacturing


LCA methodological issues
The comparison between different management waste scenarios has pinpointed some common methodological issues,
as:
    • System boundary expansion;
    • Transport process;
    • Time boundary extension;
    • Produced leachate.
In the following a short description of how each issue has been treated in one or more case studies is given.

System boundary expansion
In several LCA studies the system boundaries depend on the choice of the practitioner. But in the case of the
comparison between two products made of recycled polypropylene - boxes for fruit and vegetable market and pavement
blocks for external parking - is not sufficient to assess the best scenario. This is because each recycling option produces
an avoided product and this should modify the external environment. The system expansion is then necessary in order to
consider the changes that each option produces in the market. The environmental impact has to be calculated taking all
the produced changes into account for each recycling option. Indeed, if part of the available recycled polypropylene is
used to produce pavement blocks, then an equivalent quantity of virgin polypropylene should be used for the fabrication
of the boxes. Therefore, you have to add the environmental impacts associated with the production of virgin
polypropylene boxes to the environmental impacts of pavement blocks. Vice versa, if part of the available recycled
polypropylene is used to produce new boxes, pavement blocks will be still made in cement. Therefore, you have to add
recycled polypropylene boxes environmental impact at cement blocks environmental impact.
The two analyzed polypropylene recycling scenarios are shown in figure 1.

Table 1: Conventional and alternative scenarios
 Scenario           Blocks                                                 Boxes
 Conventional       Cement blocks                                          Recycled polypropylene boxes
 Alternative        Recycled polypropylene blocks                          Virgin polypropylene boxes


Transport process
Generally, transport processes in commercial databases are thought to simplify the assessment of transport phases. Only
two data are needed for using transport processes in databases, when the actual load approximately equals the potential
load: carried quantity and total distance. In our case, being the polypropylene boxes density very low, the actual load
(1,5 tonnes) is completely different respect to the potential load (28 tonnes) and as consequence, the environmental
impacts are overestimated. For this reason a parametric model has been developed, considering, besides the common
three load conditions (empty, full, average) any possible load of the truck.

Time boundary extension
The bottom ashes contain metal oxides and ceramic industrial sludge contain metal and asbestos; if you put them in a
landfill, these substances will represent a potential pollution source for many years.
Previous studies on landfills indicated that the potential emission over time must not be ignored and it necessary include
a long time horizons in life cycle inventories.
Several researchers have investigated two main time horizons:
     • short-term [3] or surveyable time period [4],[5], in which you could consider a one century magnitude;
     • long-term [3] or hypothetical infinite time [4],[5], when all landfilled materials can be released to the
           environmental.
The first time horizon considers the period of time until the landfill reaches a pseudo steady-state, where the chemistry
is only slowly changes and concentration may be controlled by equilibrium reactions [4].
For our studies, we have chosen this time horizon and to allocate the pollutant emissions to the specific wastes, we have
used the ecoinvent model.
As usual in LCA study, when you consider a life cycle of a product, you have to consider the output from this process
as well as the input. In case of landfill disposal study for a particular kind of waste, you should know the data for that
specific waste. Often you don’t have a waste-specific landfill but average generic landfill so you would allocate the
emission, using transfer coefficient by literature.


Produced leachate
In a disposal LCA study, you have to estimate the leachate amount to assess disposal environmental impact. There are
different tools to achieve this scope: specific softwares and soil water balance equations. An example of specific
software is US EPA’s HELP (Hydraulic Evaluation of Landfill Performance) model. HELP is a quasi–two-dimensional
hydrologic model of water movement across, into, through and out of landfills. Otherwise, you can combine Penman
and Richard’s equations to calculate a water soil balance. The main weather data required as for the HELP model as for
soil water balance equations are: precipitation, temperature, wind speed and solar radiation. The difference between the
two models is the data accuracy: in the soil water balance equations a greater accuracy can be achieved but it requires
real data with an high frequency (hourly data). This means that the soil water balance is not suitable for the assessment
of the production of the leachate in the 100 year perspective.


Conclusion
The presented case studies show how the environmental sustainability of new processes and technologies for the waste
management and recycling requires the solution of methodological issues as the expansion of system boundaries and of
time boundaries. But the required effort is fully counterbalanced by the quantitative and reliable information that an
LCA can deliver.
This information is crucial for the sustainability decision making process at any level (technology developers, system
managers, public authorities, etc.)
References
[1]     AA, RAPPORTO SUL RECUPERO ENERGETICO DA RIFIUTI URBANI IN ITALIA, ISBN 88-8286-
        145-7, ottobre 2006
[2]     Bernado E., Andreola F. Barbieri Lancellotti I.(2005), Sintered glass-ceramics and glass-ceramic matrix
        composites from crt panel glass,Juornal of the American Ceramic Society ISSN 0002-7820: vol. 88, n7, pp
        1886-1891.
[3]     Doka G. (2003), Landfills – Underground Deposits- landfarming, “ecoinvent 2000”, report n 13
[4]     Goran Finnveden, (1996), Solid Waste Treatment within the framework of life cycle assessment, International
        Journal of LCA, 1 (2), pp 74-78, (1996)
[5]     Jan-Olov Sundqvist, (1999), Life cycle assessments and solid waste- guidelines for solid waste treatment and
        disposal in LCA-, final report , Swedish Environmental Protection Agency.
[6]     Andreola F. et al, Tile and brick, Int. 16, 1, 2000, pp 6-10

								
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