HAL Id: hal-02603643
https://hal.inrae.fr/hal-02603643
Submitted on 16 May 2020
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Allocating an environmental load to wastewater sludge when sludge status moves from “waste” to “product”, a
methodological challenge
M. Pradel, Lynda Aissani, J. Villot, J.C. Baudez, V. Laforest
To cite this version:
M. Pradel, Lynda Aissani, J. Villot, J.C. Baudez, V. Laforest. Allocating an environmental load to wastewater sludge when sludge status moves from “waste” to “product”, a methodological challenge. SETAC Europe 26th Annual Meeting, May 2016, Nantes, France. pp.1, 2016. �hal-02603643�
Product x => generic allocation factor bc’
g(k,l)with matrix shape
bc’
g(k,l)=
𝛿′
1𝛼
1,1… 𝛿′
1𝛼
1,𝑙… 𝛿′
1𝛼
1,𝑞⋮
⋱
⋮
⋱
⋮
𝛿′
𝑘𝛼
𝑘,1… 𝛿′
𝑘𝛼
𝑘,𝑙… 𝛿′
𝑘𝛼
𝑘,𝑞⋮
⋱
⋮
⋱
⋮
𝛿′
𝑝𝛼
𝑝,1… 𝛿′
𝑝𝛼
𝑝,𝑙… 𝛿′
𝑝𝛼
𝑝,𝑞 Process 1 Contribution of product parameters toproduct production for each process k
=> matrix A (αk,l)
System modelling depends on
Product parameters
- Physical, chemical, stoichiometric properties - Flux/flow properties
- Used as main allocation properties between coproducts - « Product-related burden »
Process parameters
- Process operation parameters (pressure, temperature…) - Associated to process functioning
- « Process-related burden »
Allocating an environmental load to wastewater
sludge when sludge status moves from “waste” to
“product”, a methodological challenge
National Research Institute of Science and Technology for Environment and Agriculture
Conceptual framework for allocating an environmental burden to coproducts of an
indivisible system
Calculation of generic and specific allocation factors
Challenge for sludge-based products
Identify product and process parameters Product parameters can be based on stoichiometric equations for Carbon, Nitrogen (nitrification + denitrification) and Phosphorus treatments
Process parameters can be based on process treatment functioning (oxygenation rate and aeration duration)
Conclusion
A methodological framework has been developed to allocate an environmental load to several product in a joint-production system. Generic and specific allocation factors are based on product and process parameters and inventory matrices.
Sludge-based products can therefore be compared with fossil-based products as their production is charged with an environmental burden. When sludge status moves from “waste” to “product”, the wastewater treatment plant can be seen as a joint production system generating two
indivisible coproducts : the sludge and the clean water (Pradel et al., 2015). Assessing the environmental impacts of the two coproducts implies to allocate the environmental burden of the system to each of them. This is a methodological challenge that we propose to solve with the use of generic and specific allocation factors.
System modelling conceptual framework
Product 1 Product 2 Process k Process 1 Process 2 Contribution of all process parameters to each process k => δ′k = nj=1nβj,k
B’
process= 𝑖𝑏𝑐′
𝑖,𝑘or B’
product= 𝑖𝑏𝑐′
𝑖,𝑙Environmental burden calculation
Where B’process / B’product = environmental burden allocated to process k or product l ; i = input/output value bc’i,k / bc’i,l= allocation factor per process k or product l (bc : burden coefficient) ; bc’i,k / bc’i,l = f(𝛿′𝑘, 𝛼𝑘,𝑙)
Need to specify if input/output i is related to the production of
each product l : inventory matrix
’ x generic allocation factor
𝑏𝑐′
𝑖,𝑙Specific allocation factor
Generic allocation factor
𝑏𝑐′
𝑖,𝑘Inventory matrix (i,k) : relation between inputs/outputs i and
process k Inventory matrix ’ (’i,l) : relation
between inputs/outputs i and product l
Allocation factors
Generic allocation factor to be used for generic inputs/outputs
- To be used for common inputs/outputs to all the process (infrastructures…)
- To be used when inputs/outputs cannot be specified to one or several process
Specific allocation factor to be used for specific inputs/outputs
- To be used for specific inputs/outputs
- Can also be used as generic allocation factor
build with 1 and 0 : 1 = presence
0 = absence
Marilys Pradel1,3, Lynda Aissani2, Jonathan Villot3, Jean-Christophe Baudez1
and Valérie Laforest3
marilys.pradel@irstea.fr
1 Irstea, UR TSCF, France; 2 Irstea, UR OPAALE, France;
3 Université de Lyon, Ecole des mines de Saint-Etienne, I. Fayol, UMR 5600 EVS, France
PRADEL, M., AISSANI, L., VILLOT, J., BAUDEZ, J.C. , LAFOREST, V., 2015. From waste to product: a paradigm shift in LCA applied to wastewater sewage sludge. SETAC Europe 25th Annual Meeting, Barcelona, Spain, 3-7 May 2015.
Product 1 Product 2 Process 2 Product 1 Product 2 Input/output i Allocation factor /process bc’i,k i : input/output k : process, l : product Allocation factor /product bc’i,l
Generic allocation factor for
each process and each product Generic allocation factor for each product
Generic allocation factor for each process
Need to specify if input/output i is specific to each process k :
inventory coefficient
i,kmultiplied with previous result
x matrix A
Specific allocation factor
/ process
Specific allocation factor
/ product
Need of an environmental burden to the production of sludge-based products to allow system comparison
Production Use Manufactured product End-of-life Waste as raw material Use End-of-life Production Use End-of-life Sludge-based product