BEZERRA, Indira Q. M. Use of babassu coconut fiber (Orbignia, sp) as a componente of natural geotextile to protect soil slopes. 2022. 97 p. Tese (Doutorado em Tecnologia Nuclear) -Instituto de Pesquisas Energéticas e Nucleares -IPEN -CNEN/SP. São Paulo A worldwide concern is the destination of residues, including natural and biodegradable ones. The shell of the babassu nut found in the northern and northeast regions of Brazil is an example of residue, which is generated from the extraction of babassu nuts for the main purpose of extracting its seeds. Therefore, this work aimed to identify a sustainable destination for the babassu nut epicarp, corresponding to 13% of the fruit. A natural geotextile was implemented, also denominated as "biomanta", to protect the soil of embankments. The "biomanta" was manually produced utilizing the shell's fiber of babassu nut; and it was protected by a mesh made of biodegradable polypropylene. The "biomanta" was laid in a natural embankment for a period of 2 months, during the raining season in the city of Araguaina in the Brazilian state of Tocantins. The embankment was divided into blocks with some blocks covered by the "biomanta" and grass and another blocks without covered by the "biomanta" and grass. Across the bottom of the embankment was collected water and soil drained from the rainfall over that entire period. The results indicated that, in the blocks protected by the "biomanta", the amount of water drained was 32% less than the areas without it; and that the amount of soil drained down by the rain was 80% less in the blocks covered by the "biomanta". In addition, the babassu nut epicarp presented a specific mass of 1.083 g/cm³, absorption of water after 24 h of 0.75% and degradation of 8.87% when laid on the embankment soil.