The now concluded TRUST ALUM project addressed one of the major challenges in water management in the Baltic Sea Region ‒ eutrophication, a process that leads to excessive algal blooms, which harms ecosystem and human health. Many lakes in the region still suffer from high phosphorus loads due to mismanagement. If not addressed, these phosphorus hot spots will continue to harm the Baltic Sea.

Our solution was to promote the ALUM water treatment method, which effectively reduces eutrophication in heavily polluted lakes. The ALUM treatment method involves adding a phosphorus-binding salt (polyaluminium chloride or PAC) to permanently capture phosphorus in lake's sediments. ALUM treatment is a safe chemical method, which is cost-effective and provides long-lasting benefits. Although ALUM has been successfully used in Swedish lakes for over 60 years with many positive examples, until now, it has not been adopted in the Baltic countries. The main barriers included lack of know-how, skepticism about the treatment outcomes, perceived high costs, and fears about the safety of aluminum.

Our project built trust in the ALUM method among target groups by demonstrating its effectiveness and safety for lakes, by performing a successful pilot treatment in Lake Velnezers, Riga (Latvia). Broader adoption of the method was fostered by creating supportive tools and establishing an expertise linking hub to share the knowledge and good practices. By overcoming identified barriers and challenges, our project enhanced water quality in the region. Interreg BSR funding was crucial for this initiative, as it supports demonstration and dissemination activities, helping us to prove the effectiveness of the ALUM method and promote its adoption on a wider scale.