Life Cycle Assessment of Phosphorus Sources from Phosphate ore and urban sinks:Sewage Sludge and MSWIncineration fly ash

Document Type: Original Research Paper

Authors

1 Department of Civil and Environmental Engineering, Chalmers University of Technology, 412 96, Gothenburg,Sweden

2 Department of Energy and Environment, Chalmers University of Technology, 412 96, Gothenburg,Sweden

3 Sino-Carbon Innovation &Investment Co., LTd, Beijing, P.R.China

Abstract

Urban sinks accumulate phosphorus and other elements and may serve as sources of secondary
raw materials. This paper evaluates phosphorus sources based on their environmental impact. In a life cycle
assessment (LCA) the conventional production was used as a yardstick against which tomeasure the performance
of two recycling options: spreading of sewage sludge and phosphorus recovery from municipal solid waste
incineration fly ash (MSWA). When compared as three gate-to-gate processes, the sludge spreading had the
lowest potential environmental impact, except in the impact categories eco- and human toxicity. In the future, the
sludge spreading could potentially outperform the conventional process also with regard to toxicity, provided its
Hg and Cu content can be reduced. Phosphorus extracted from the MSWA had the highest impact, except in
relation to eutrophication. The benefits of avoiding the conventional production were greater than the sludge
recycling impacts for all categories except toxicity. When conventional production is substituted by the MSWA
recycling, the eutrophication and land-use impacts are avoided, while the impacts in other categories are
considerable. The development needs identified for this method include substitution of HCl, reduced water
consumption, and reduction of the product’smetal content. Solutions to all of these challenges have been proposed
and are currently being tested.

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