[1] Aruja was born in Soontaga, Kreis Dorpat, in the Governorate of Livonia, and was initially schooled in his birthplace.
After earning his M.Sc., he worked in 1938–1939 as a physics laboratory assistant in the Tallinn Technical University, then moved to England, where he received his PhD in 1943.
(The libraries had been unable such books during the Soviet occupation due to the Iron Curtain.)
Eventually, Aruja succeeded in delivering over 7000 boxes of books to various Estonian libraries, including all the major ones.
As an archivist and librarian, Aruja collected eight roomfuls, totalling about 236 square metres, worth of archival material, resulting in one of the most extensive cultural compendiums of Estonian expatriates.