REDUCING EMISSIONS TO THE BALTIC SEA BY TURNING NUTRIENTS AND CARBON INTO BENEFITS

The report details the results of the BONUS RETURN project, which identified and evaluated ecotechnologies for recovering nitrogen, phosphorus, and carbon from wastewater and agriculture in the Baltic Sea Region. While agricultural waste recovery often showed positive net present value, wastewater technologies typically required expensive infrastructure, leading to negative net present values. The project emphasizes that transitioning to a circular nutrient economy requires shifting away from linear 'silo' thinking, harmonizing EU regulations for phosphorus, and adjusting fertilizer pricing to account for environmental externalities.

• Phosphorus levels in the Baltic Sea continue to rise due to runoff from the drainage basin and internal loading from anaerobic sediments, driving annual cyanobacterial blooms that import approximately 370,000 tons of nitrogen per year via atmospheric fixation.
• The project identified 25 recovery and reuse solutions in agriculture and 28 in the wastewater sector relevant to the Baltic Sea Region. Mature technologies include struvite crystallization and ammonia stripping, while promising new ones include in situ adsorption of dissolved phosphorus and biocoal production from sludge.
• Cost-benefit analyses across three catchment areas indicate that ecotechnologies for circulating nutrients from agricultural wastes can have a positive Net Present Value (NPV), whereas wastewater management ecotechnologies generally show negative NPVs due to high infrastructure costs.
• SWAT model simulations showed that while selected ecotechnologies provided co-benefits like bio-based fertilizer and energy, they were less effective at reducing nutrient loads than traditional hotspot-targeted Best Management Practices. For example, nutrient extraction in the Slupia River reduced nitrogen and phosphorus by 6-7%.
• The economic viability of recovered nutrients is hindered by the low market price of conventional chemical fertilizers, which do not account for environmental externalities.
• There is a significant regulatory gap in the EU regarding phosphorus; while nitrogen reuse is regulated by the Nitrates Directive, no such harmonized norm exists for phosphorus, which is currently managed by fragmented national directives.
• The reuse of sewage sludge on agricultural land in Sweden is a highly polarized issue, with perceived risks regarding microplastics, PFAS, and other contaminants often outweighing the perceived benefits.
• Linear and 'silo' thinking in governance and management impedes the transition to a circular economy, as wastewater systems are traditionally designed for waste removal rather than resource recovery.

APA

Stockholm Environment Institute (2020). REDUCING EMISSIONS TO THE BALTIC SEA BY TURNING NUTRIENTS AND CARBON INTO BENEFITS. https://www.sei.org/wp-content/uploads/2020/12/bonus-return-final-report-dec-2020.pdf

Chicago

Stockholm Environment Institute. REDUCING EMISSIONS TO THE BALTIC SEA BY TURNING NUTRIENTS AND CARBON INTO BENEFITS. 2020. https://www.sei.org/wp-content/uploads/2020/12/bonus-return-final-report-dec-2020.pdf.

Wikipedia

{{cite report |author=Stockholm Environment Institute |title=REDUCING EMISSIONS TO THE BALTIC SEA BY TURNING NUTRIENTS AND CARBON INTO BENEFITS |date=December 2020 |url=https://www.sei.org/wp-content/uploads/2020/12/bonus-return-final-report-dec-2020.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{stockholmenvironmentinstitute2020reducing, author = {{Stockholm Environment Institute}}, title = {{REDUCING EMISSIONS TO THE BALTIC SEA BY TURNING NUTRIENTS AND CARBON INTO BENEFITS}}, institution = {Stockholm Environment Institute}, year = {2020}, month = dec, url = {https://www.sei.org/wp-content/uploads/2020/12/bonus-return-final-report-dec-2020.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }