A Feasibility Analysis Methodology for Decentralized Wastewater Systems - Energy-Efficiency and Cost

Centralized wastewater treatment, widely practiced in developed areas, involves transporting wastewater from large urban areas to a large capacity plant using a single network of sewers, whereas decentralization is the concept of wastewater collection, treatment and reuse at or near its point of generation. Smaller decentralized plants can achieve extensive reclamation and wastewater management with energy-efficient reclaimed water pumping, modularized expansion and lower capital investment. We devised a methodology to preliminarily assess these alternatives using local constraints and conducted a feasibility analysis for each option. It addressed various scenarios using the pump-back energy consumption, sewer and treatment plant construction and capacity expansion cost. We demonstrated this methodology by applying it to the Hollywood vicinity (California). In this study, the decentralized configuration was more economical and energy-efficient than the centralized system. The pump-back energy consumption was about 50% of the aeration energy consumption for the centralized option.