Life-Cycle
Energy Use and Greenhouse Gas Emissions
of a Building-Scale Wastewater Treatment and Nonpotable Reuse System
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Abstract
Treatment and water
reuse in decentralized systems is envisioned
to play a greater role in our future urban water infrastructure due
to growing populations and uncertainty in quality and quantity of
traditional water resources. In this study, we utilized life-cycle
assessment (LCA) to analyze the energy consumption and greenhouse
gas (GHG) emissions of an operating Living Machine (LM) wetland treatment
system that recycles wastewater in an office building. The study also
assessed the performance of the local utility’s centralized
wastewater treatment plant, which was found to be significantly more
efficient than the LM (79% less energy, 98% less GHG emissions per
volume treated). To create a functionally equivalent comparison, the
study developed a hypothetical scenario in which the same LM design
flow is recycled via centralized infrastructure. This comparison revealed
that the current LM has energy consumption advantages (8% less), and
a theoretically improved LM design could have GHG advantages (24%
less) over the centralized reuse system. The methodology in this study
can be applied to other case studies and scenarios to identify conditions
under which decentralized water reuse can lower GHG emissions and
energy use compared to centralized water reuse when selecting alternative
approaches to meet growing water demands