**4. Experimental validation of filamentous algae co-culture**

In the case study, a total of 25 freshwater algae strains from 11 genera (**Table 1**) were selected from the Norwegian Culture Collection of Algae (NORCCA, www. norcca.no) aiming to test the suitability of phytoremediation to local climate condition. According to the record from a local WWTP (VEAS: VeasSelvkost AS, Slemmestad, Norway), the temperature of municipal discharge primarily ranges from 10 to 15°C over the year. This range was thereby used a criterion in the case study for



**Table 1.** *Algae selection for the experimental test. (unicellular species are included for a point of comparison).*
