Multi-criteria analysis of strategies towards sustainable recycling of phosphorus from sewage sludge in Austria

• Published in: Journal of environmental management 2024-06, Vol.362, p.121339-121339, Article 121339
• Main Authors: Long, A., Weber, N., Krampe, J., Peer, S., Rechberger, H., Zessner, M., Zoboli, O.
• Format: Article
• Language: English
• Subjects: Austria; Circular economy; Life cycle assessment; Material flow analysis; Metals, Heavy; Phosphorus; Phosphorus recovery; Recycling; Resource policy; Sewage; Waste Disposal, Fluid - methods; Wastewater - chemistry
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2024.121339

To promote optimal phosphorus (P) recovery from municipal wastewater and sewage sludge with viable legal instruments, it is imperative to understand the regional and national consequences of different legal requirements for recycling. In this study we develop a scenario-based analysis to assess the environmental and economic impact of different national P recovery strategies in the context of a detailed representation of the existing Austrian wastewater infrastructure. This assessment combines material flow analysis, life cycle assessment and life cycle costing and includes the indicators P recycling rate, P utilization degree, heavy metal removal rate, share of heavy metals’ content in wastewater redirected to agricultural soils, global warming potential, cumulated energy demand, terrestrial acidification potential, volume of freight transport and annual costs. The following main conclusions can be drawn. P recovery from ash shows the highest potential regarding the utilization of P from wastewater. A high P utilization from wastewater should rely on recovery technologies that decontaminate products, otherwise pollutant loads to agricultural soils might increase. P recovery to the extent of 60–85 % of P in WWTPs influent can be achieved by savings/costs of −0.8 to +4.7 EUR inhabitant−1 yr−1 in addition to current cost of the wastewater treatment/sludge disposal system. Key factors to be considered for costs are the choice of recovery process, revenues from products, and the use of existing incineration infrastructure. P recovery can lead to the reduction of greenhouse gas emissions in Austria if nitrous oxide emissions from sludge incineration are limited and efficient heat utilization strategies are implemented. There is a trade-off in terms of environmental and economic costs in choosing a more centralized or decentralized mono-incineration strategy. •The analysis considers a full representation of Austrian wastewater infrastructure.•P- recovery up to 85 % of P in wastewater can be achieved.•Additional costs of up to 5 EUR per inhabitant and year must be expected.•P recovery may lead to a reduction of GWP emissions and CED of wastewater disposal.•Trade-offs between environmental and economic costs must be considered.