Waste Load Allocation in Rivers: A State of the Art Review and Prospects for Future Studies

Waste load allocation (WLA), which refers to determination of the optimum treatment level of waste load discharged into a river by every pollution source, has attracted the researchers and policy makers during the last decades. In most proposed WLA models, objectives and constraints such as minimizing the treatment costs, equity considerations in distributing costs, minimizing the amount of river water quality violations, and minimizing the duration of violation intervals are taken into account. In spite of the importance of the researches on WLA in rivers, there is only one paper by de Melo and Câmara (1994) in the literature which present an integrated review on the main objectives and constraints in river water quality management models. Recently, modeling important uncertainties and dischargers’ utilities have become the major focus of many WLA researches. In this paper, more than 60 major papers in the field of WLA in rivers are reviewed and their main aspects, virtues, and limitations are discussed. Also, some prospects and ideas for improving the current models in future are presented.