MFA Flashcards
Define material flow analysis
• Tool for studies of flows and stocks of material in society and environment, defined in
space and time
- Conservation of mass (and energy)
- “Metabolism of anthropogenic and geogenic systems”
- Defines terms and procedures to establish material balances of systems
Define substance flow analysis
SFA is similar to material flow analysis but focuses on flows and stocks of a single substance.
Objectives of MFA
• Describe material flows and stocks
- Reduce system complexity while maintaining a solid basis for decision making
• Assess relevant flows and stocks quantitatively, checking mass balance, sensitivities, and
uncertainties
- Present results in reproducible, understandable, transparent fashion
• Use results for managing resources, the environment and wastes
- Monitor accumulation or depletion of stocks, describe or predict future environmental loadings
- Design of environmentally beneficial goods, processes and systems
• MFA connects sources, pathways and sinks of a material
The steps of MFA methodology
- Goal and systems definition
- Process chain analysis
- Accounting and balancing
- Modeling and evaluation
Goal and system definition
The system definition includes:
• formulation of the target questions
• definition of scope & system boundaries
The target questions are defined according to the primary objectives
The scope defines the spatial, temporal and functional extent of the studied objects. Flows are always accounted on the basis of a temporally defined period.
The system boundary defines the start and the end of the material flows
Process chain analysis
Definition of the process for which the inputs and outputs are to be determined quantitatively.
Accounting and balancing
The mass conservation principle is used to balance the inputs and outputs of process and systems during steady state.
The balancing is used to check accuracy of empirical data, to improve consistency and fill in missing data. This step may be assisted by computer simulation.
In the case of SFA, one need to determine concentrations before balancing the substances. This part is done after balancing of goods.
Modeling and evaluation
The modeling may be applied in the basic form of bookkeeping or with increasing complexity as static and dynamic modeling. The evaluation of the results is related to the primary interest and basic assumptions.
The criteria may focus on:
• Indication of specifically known impacts per unit flow
• Indication of a generic environmental pressure potential
Use of MFA/SFA
- Part of Environmental Impact Assessment
- Studies of remediation of hazardous waste deposits
- Design of air pollution strategies
- Nutrient management in watersheds
- Planning of soil monitoring programs
- Sewage sludge management programs
Limitations of MFA/SFA
- MFA/SFA usually can not alone support decisions for environmental engineering or management
- Often retrospective, but can be used in prospective studies as well
