Expertise Linking Hub Completed with Successful ALUM Treatment in Riga

The Expertise Linking Hub has been finalized by release of an extensive report documenting the pilot ALUM treatment in Lake Velnezers, Riga, Latvia. This marks a significant milestone for the TRUST ALUM project, aimed at increasing trust in ALUM water treatments for improving heavily polluted lakes in the Baltic countries and the Baltic Sea Region.

For the first time in the Baltic States, the ALUM method – an effective but often misunderstood water restoration approach – was applied to tackle persistent eutrophication in a natural lake. Lake Velnezers had long suffered from legacy phosphorus pollution, resulting in critically low oxygen levels, high internal nutrient loading, and even a fish kill just months before the treatment.

Science in Action

The final report, “Restoring lakes using the ALUM method in the Baltic states: planning, design, implementation, and social engagement”, presents a comprehensive guide to the full implementation cycle:

• Pre-treatment monitoring over 15 months, establishing a detailed baseline of physico-chemical and biological conditions.
• Legal navigation through national regulations and environmental permits.
• Innovative treatment logistics, including transportation of Swedish equipment (a treatment boat build specifically for Lake Velnezers treatment) and precise chemical dosing.
• Active public engagement, with on-site communication tents, public demos, and transparent reporting via national media and key stakeholder engagaement.

Real Impact on Water Quality

The ALUM method, which involves applying polyaluminium chloride to bind phosphorus in sediments, led to rapid improvements:

• Total phosphorus levels dropped by ~50% across all water layers.
• Orthophosphate, the bioavailable form of phosphorus, saw reductions up to 99% in bottom layers.
• Water transparency tripled within a month post-treatment, a visible sign of restored ecological health.
• Preliminary post-treatment data already place the lake within Good to High EU Water Framework Directive status thresholds.

Building Societal Trust

One of TRUST ALUM core goals was to shift perceptions of ALUM treatment by grounding it in robust science, open dialogue, and stakeholder collaboration. The pilot in Riga included:

• National and local stakeholder consultations.
• Public outreach via media and on-site engagement.
• Scientific demonstrations like the “jar test” to visualize the treatment process.

The Expertise Linking Hub

The reports all together forms the Expertise Linking Hub to ease further ALUM water treatment application in Baltic lakes and beyond:

Part I –  Expertise linking HUB | Eutrophication

Part II – Expertise linking HUB | ALUM treatment concept

Part III – Expertise linking HUB | Key literature

Part IV – Expertise linking HUB | Target group database

Part V – Expertise linking HUB | Restoring lakes using the ALUM method in the Baltic states

Programme Manual Online

Choose