Minimizing Energy Consumption in Decentralized Wastewater Collection and Treatment Systems

摘要

Centralized wastewater treatment, widely practiced in developed areas, involves transporting wastewater from large urban or industrial areas to a large capacity plant using a single network of sewers. Alternatively, the concept of wastewater collection, treatment and reuse at or near its point of generation is called decentralized wastewater treatment (Tchobanoglous and Crites, 1998). Smaller decentralized plants with energy-efficient reclaimed water pumping, modularization of expansion and minimum capital investment can meet the increasing need for reclamation and wastewater management accessibility in rapidly developing regions. Hence, a feasibility analysis and comparison methodology subject to user-defined constraints for a decentralized configuration of several treatment plants and collection networks is necessary. We devised a methodology to preliminarily assess the feasibility of installing decentralized systems, based on local needs. It evaluates the following parameters and their combinations to develop various scenarios: Pump-back energy consumption, Sewer construction cost, Capacity expansion cost. We applied this methodology to the case study of Hollywood and a typical central treatment plant. The reclaimed water distribution network, sewer expansion and pump station expenditure, and capital expansion for completely centralizing wastewater collection and reclamation exceeded the cost of the same for a decentralized system. Also, the energy consumption for pumping back reclaimed water is about twice the aeration energy consumption and significant fraction of the treatment energy consumption. In this study, decentralization was evidently the more favorable solution.