The environmental benefits and burdens
of phosphorus recovery in
four centralized and two decentralized municipal wastewater systems
were compared using life cycle assessment (LCA). In centralized systems,
phosphorus recovered as struvite from the solids dewatering liquid
resulted in an environmental benefit except for the terrestrial ecotoxicity
and freshwater eutrophication impact categories, with power and chemical
use offset by operational savings and avoided fertilizer production.
Chemical-based phosphorus recovery, however, generally required more
resources than were offset by avoided fertilizers, resulting in a
net environmental burden. In decentralized systems, phosphorus recovery
via urine source separation reduced the global warming and ozone depletion
potentials but increased terrestrial ecotoxicity and salinization
potentials due to application of untreated urine to land. Overall,
mineral depletion and eutrophication are well-documented arguments
for phosphorus recovery; however, phosphorus recovery does not necessarily
present a net environmental benefit. While avoided fertilizer production
does reduce potential impacts, phosphorus recovery does not necessarily
offset the resources consumed in the process. LCA results indicate
that selection of an appropriate phosphorus recovery method should
consider both local conditions and other environmental impacts, including
global warming, ozone depletion, toxicity, and salinization, in addition
to eutrophication and mineral depletion impacts
