Water Footprint of a Decentralised Wastewater Treatment Strategy Based on Membrane Technology

Abstract

Growing pressure on water resources has led to the search for alternatives to conventional wastewater treatment plants (WWTPs). Centralized wastewater treatment systems provide a single treatment scheme but are not especially adequate for water reuse as large flows of reclaimed water need to be efficiently managed. As an alternative, a new concept of wastewater treatment based on decentralized systems arise, which comprises collection, treatment and final disposal and/or reuse of water in an area close to the point of origin. Turkey is severely affected by water scarcity, thus, it is essential to improve water recovery through efficient technologies that allow nutrient recovery and have the potential for water reuse for irrigation to counteract consumption of drinking water. In this study, a decentralized membrane bioreactor (MRB) plant in Turkey was evaluated within the framework of the most relevant environmental indicators under the approach of Life Cycle Assessment: climate change (CC) and eutrophication potential (EP). In addition, the water scarcity footprint indicator was estimated using the available remaining water method (AWARE). This category should be taken into account when addressing the potential benefits associated with water reuse. Once the impacts of the plant under study were determined, a sensitivity analysis was carried out considering different solid retention times (SRT) in the MBR operation and the influence of the impacts associated with the construction phase. The sub-processes with the greatest impacts are electricity consumption in the operational phase and infrastructure in the construction phase. These impacts are significantly reduced when water is reused for irrigation of green areas, approximately 23% in CC, 4.8% in EP and 133.8% in AWARE indicator. No significant influence of the SRT variable was observed on environmental impacts for the range examined, since it only affected the eutrophication category, determining an optimum SRT value of 50 days for the MBR operation.