Quantification of sustainability index for the wastewater recovery technologies: a decision support approach for circular city adaptations

Abstract

The concept of the circular city is gaining more and more attention nowadays due to its reuse/recover/recycle applications for circulating the resource. The authorities need decision support tools to determine which sources can be recovered and what are the best applicable technologies. This study proposes a decision-making approach that calculates sustainability index (SI) for wastewater resource recovery strategies. The resource recovery plan consists of the preliminary steps to determine the wastewater streams to be recovered and their alternative technologies to implement. Analytical hierarchy process (AHP) is used for the composition of SI, which provides a systematic evaluation by listing the criteria that contribute to sustainability. Lastly, the fuzzy inference engine combines the fundamental components of sustainability defined with AHP. It quantifies the SI, which is reported as an index value with the sustainability class and its membership degree. Therefore, the novelty of this study is providing a holistic approach for the sustainability assessment of wastewater recovery technologies due to including a resource recovery plan and allowing the evaluation of symbiosis strategies and quantification of SI by using fuzzy logic. The proposed approach is demonstrated with a scenario for nutrient recovery technologies from wastewater, and according to the scenario, membrane technology has the highest SI with 8.36. The numerical value for SI and priority weights communicates between stakeholders of the circular city while deciding on the resource recovery technologies for wastewater recovery. The proposed approach was easily applied and was convenient for handling uncertain data and linguistic expert opinions.