Life cycle assessment of two decentralized water treatment systems combining a constructed wetland and a membrane based drinking water production system

Abstract

Decentralized (waste) water treatment technologies (DWTS) are suitable for rural areas that are not connected to conventional (municipal) treatment systems due to the longer transport distances. However, the sustainability of DWTS is still debatable. Therefore, the main goal of this study was to use the Life Cycle Assessment tool to perform the life cycle impact assessment of two different decentralized water treatment systems operated in Belgium. The first one was a mobile constructed wetland treating grey water (Scenario 1) at music festivals, coupled to a membrane based drinking water production system (100 m3 of potable water production out of 400 m3 of wastewater generation per festival). The second one was a vertical flow constructed wetland treating black water (Scenario 2) at a restaurant (135 visitors/day), also coupled to a membrane system. Comparison was performed with conventional alternatives (PET bottled water supply and a public drinking water supply, respectively). In most impact categories, Scenarios 1 and 2 had roughly an order of magnitude lower impact than their conventional alternatives. Sensitivity analysis was also performed. In scenario 1, the distance travelled for both the mobile constructed wetland and the PET bottles was varied. In Scenario 2 the distance of the restaurant from a drinking water supply and a sewerage system was varied. These results were also encouraging, showing that the DWTS are still environmentally feasible compared to their conventional alternatives at the shortest distance studied (Scenario 1: 175 km and Scenario 2:75 m). Therefore, DWTS can be considered environmentally beneficial under certain conditions.