Production of selenium-enriched microalgae as potential feed supplement in high-rate algae ponds treating domestic wastewater

This study assessed the selenium (Se) removal efficiency of two pilot-scale high-rate algae ponds (HRAPs) treating domestic wastewater and investigated the production of Se-enriched microalgae as potential feed supplement. The HRAP-Se had an average Se, NH4+-N, total phosphorus and COD removal efficiency of, respectively, 43%, 93%, 77%, and 70%. Inorganic Se taken up by the microalgae was mainly (91%) transformed to selenoamino acids, and 49–63% of Se in the Se-enriched microalgae was bioaccessible for animals. The crude protein content (48%) of the microalgae was higher than that of soybeans, whereas the essential amino acid content was comparable. Selenium may induce the production of the polyunsaturated fatty acids omega-3 and omega-6 in microalgae. Overall, the production of Se-enriched microalgae in HRAPs may offer a promising alternative for upgrading low-value resources into high-value feed supplements, supporting the drive to a circular economy.This work has been financially supported by the Special Research Fund (BOF: BOFCHN2017000801) from Ghent University (Belgium) and the Chinese Scholarship Council (CSC:201606030023). Ivet Ferrer is grateful to the Government of Catalonia (Consolidated Research Group 2017 SGR 1029). The authors acknowledge Maria Josep Curto Panisello from the Universitat Politècnica de Catalunya·BarcelonaTech for her assistance with the lab work.Peer ReviewedObjectius de Desenvolupament Sostenible::12 - Producció i Consum ResponsablesObjectius de Desenvolupament Sostenible::6 - Aigua Neta i SanejamentObjectius de Desenvolupament Sostenible::3 - Salut i BenestarPostprint (author's final draft