Investigating the Sustainability Improvement of Municipal Wastewater Treatment Plants using the eco-Efficiency Index: Case Study Mashhad

Wastewater treatment plants require the use of materials and energy, manpower, and initial investment to carry out the treatment and disposal of contaminants. In the present study, the economic and environmental aspects of Al-Teymour and KhinArab wastewater treatment plants have been evaluated using the eco-efficiency index. The results represent that the eco-efficiency index of KhinArab treatment plant based on the removed organic matter and nutrients, as well as the environmental impacts of the life cycle is greater than Al-Teymour treatment plant. In order to improve sustainability, three scenarios are analyzed including the construction of composting unit, reduction of energy consumption, and reduction of chlorination. The results show that if the removed organic load or nutrients are selected as the environmental index, the first scenario with the eco-efficiency index of 0.09 and 0.14 million Rials per the removed organic load or 1.22 and 1.48 million Rials per the removed nutrients, it is the most suitable option for Al-Teymour and KhinArab treatment plants, respectively. In addition, if the eco-efficiency index based on life cycle environmental impacts is considered, the second scenario is the best option with eco-efficiency index of 2.44×103 and 2.90×103 million Rials per the environment impact index of the life cycle for Al-Teymour and KhinArab treatment plants, respectively. This study represents that the WWTPs should be considered not only from an environmental viewpoint but also from an economic viewpoint; as a result, in order to provide a comprehensive analysis of the WWTPs, these two aspects should be considered together.