A decision support tool for selecting the optimal sewage sludge treatment

Area of Science:

• Environmental Science
• Waste Management
• Decision Science

Background:

• Sewage sludge presents both valuable resources (nutrients, organic matter) and risks from organic contaminants (OCs).
• Incineration is often preferred over agricultural recycling in Europe due to concerns about OCs.
• Effective sludge treatment strategies are crucial for resource recovery and environmental protection.

Purpose of the Study:

• To develop and validate a Multi-Attribute Value Theory (MAVT)-based decision support tool (DST) for sewage sludge treatment.
• To integrate expert knowledge and environmental risk assessment, particularly for organic contaminants, into sludge management decisions.
• To provide a transparent and adaptable framework for comparing different sludge treatment options.

Main Methods:

• A Multi-Attribute Value Theory (MAVT) approach was employed to create the decision support tool (DST).
• Essential decision criteria were identified and weighted by water utility experts.
• A scoring method was developed to assess the environmental risks associated with organic contaminants (OCs) in sludge treatment.

Main Results:

• The DST assigned preference scores to various sludge treatment methods, with sludge pyrolysis scoring highest (0.629).
• Composting (0.580) and incineration (0.484) received lower preference scores in the validated case study.
• WWTP-specific factors, such as operating environment and criterion weighting, influenced the preference scores.

Conclusions:

• The developed DST is a useful and adaptable tool for sewage sludge treatment decision-making.
• The DST can enhance the transparency, comprehensibility, and comprehensiveness of the decision process.
• Further research is needed to address data gaps concerning nutrient availability, organic matter quality, and OC impacts across different treatment methods.