عنوان مقاله [English]
This papers aims at developing a new methodology for Waste Load Allocation (WLA) to the effluent dischargers in Zarjub river basin in Gilan Province, Iran. In waste load allocation problems, besides maintaining the river water quality, minimizing the effluent treatment costs should also be taken into account. The concept of Nash Bargaining Equilibrium and Borda scoring social choice Method are utilized for finding the best solution among a number of alternatives. Each alternative is a combination of treatment scenarios for the dischargers. These alternatives form a compromise set which are obtained using the Fallback Bargaining Procedure. The methodology introduced in this paper can be considered as a substitute [A1] for the methodology developed in Mahjouri and Bijani-Manzar (2013). To investigate the impact of each alternative on river water quality, the concentration of Dissolved Oxygen in a control point is determined using Transfer Coefficients which are derived from a water quality simulation model. A penalty function is used to calculate the amount of penalty cost assigned to the violations from the standards in the control point. In this research compromise sets were primarily selected among alternatives, using the Borda scoring social choice method. Then, all alternatives in the compromise set were investigated to find out whether they are Nash Equilibriums. If the number of Nash Equilibrium alternatives was more than unity, the Nash Bargaining Function was used for finding the best solution among them. The results of the two mentioned procedures were then compared to select the final alternative based on the allocated costs to the total dischargers and the amount of violation from the river water quality standards resulted from the selected alternative. In the final step, the Extended Trading Ratio System (ETRS) [A2] is utilized for exchanging the allocated amount of discharges to the dischargers which decreased the total allocated cost to dischargers. On the whole, the proposed methodology can find a final solution among a set of alternatives which in addition to maintaining the river water quality condition, can lessen the total treatment costs.