A method for appropriate sizing of sewerage zones from sustainability and resilience perspectives using scaled decentralization.

Abstract

The sustainability of wastewater infrastructure is an increasing consideration for wastewater practitioners. Researchers have debated whether centralized or decentralized sewerage infrastructure should be adopted. Considering the trade-offs in both approaches, a balanced integration of decentralization and centralization with an emphasis on implementing the infrastructure at an optimal scale is suggested. In the present work, the trade-offs between these configurations through various sustainability and resilience parameters are discussed first. Further, a novel methodology is developed to prevent mega-centralization in cities, by proposing appropriate sizing of the sewerage zones for a city or a region from sustainability and resilience perspectives. The study demonstrates the application of the proposed method for sewerage planning in new cities. Also, it demonstrates the usage of the method for existing cities sewerage infrastructure across four urban local bodies, namely Pune, Mumbai, Navi Mumbai, and Pimpri Chinchwad. While Pune, Navi Mumbai and Pimpri Chinchwad have distributed capacities of Sewage Treatment Plants (STPs) across the city, Mumbai is observed to have highly centralized and highly decentralized STPs. By assessing the deviations of installed STP capacities from the proposed sizing, a discussion is made regarding retrofitting options for sewerage infrastructure. This work is significant for the urban planning of sewerage infrastructure, is relevant for diverse stakeholders, and can serve as a wastewater management strategy to achieve sustainability and resilience.