Equilibrium strategy based waste load allocation using simulated annealing optimization algorithm

Area of Science:

• Environmental Science
• Environmental Management
• Water Resource Management

Background:

• Waste load allocation (WLA) problems involve balancing economic development with environmental protection.
• Conflicts often arise between regulatory bodies and dischargers in managing water quality.
• Existing WLA models may not adequately address multi-stakeholder conflicts and economic-environmental trade-offs.

Purpose of the Study:

• To develop an equilibrium strategy for the waste load allocation problem using a simulated annealing algorithm.
• To apply and compare Stackelberg and Nash bargaining games for resolving stakeholder conflicts in WLA.
• To optimize WLA programs and environmental penalty tariffs (EPT) considering both economic and environmental factors.

Main Methods:

• Simulated Annealing (SA) algorithm coupled with the QUAL2Kw model for optimal WLA.
• Application of Stackelberg and Nash bargaining game theories to model stakeholder interactions.
• Case study analysis of a multi-stakeholder WLA problem in the Gheshlagh River, Iran.

Main Results:

• The Stackelberg game allocated lower biochemical oxygen demand (BOD) removal rates to dischargers compared to the Nash bargaining game.
• The environmental penalty tariff (EPT) determined by Iran's Department of Environment (DoE) was 11.25 Rials/(gr/month) in the Stackelberg game and 3.6 Rials/(gr/month) in the Nash bargaining game.
• The EPT from the Stackelberg game closely aligns with the current DoE tariff for non-compliant BOD discharges.

Conclusions:

• The developed SA-based equilibrium strategy effectively balances economic and environmental concerns in WLA.
• The Stackelberg game model provides a more realistic approach to WLA with higher environmental penalty tariffs, aligning better with regulatory goals.
• This approach offers a robust framework for optimizing water quality management in complex, multi-stakeholder river systems.