Banca de DEFESA: RAFAEL GOMES DA MOTA GONÇALVES

Gravel from Marine Well Drilling as a Source for Organomineral Fertilizers for Use in Low Fertility Soils.

Drilling residue, nutrient reuse, fertilizer, alternative technology.

Drilling gravel is rock fragments obtained during offshore oil well drilling operations. Its composition contains chemical elements that are important for soil fertility, such as potassium, calcium, phosphorus, magnesium, among others. Therefore, its use has been considered as an option to improve soil quality and provide nutrients for plants, mainly as a fertilizer alternative for poor or degraded soils. The general objective of the thesis was to evaluate the feasibility of using drilling gravel for use in soils with low fertility, as well as a mineral matrix for the production of organomineral fertilizer to be used in agricultural (corn) and forestry (eucalyptus) species. In order to meet the proposed objectives, the thesis was divided into four distinct chapters. In Chapter I, the physico-chemical characterization of gravel from the pre- and post-salt layers is carried out; as one of the obstacles observed in chapter 1 was the excess of sodium in the gravel, Chapter II proposes a treatment protocol for sodium removal, analyzes the dynamics of gravel with and without treatment in low fertility soils, and makes a comparison with standards regulations, aiming to classify it as solid waste. Finally, in Chapters III and IV, the effect of gravel as a mineral matrix for organomineral fertilizers is analyzed, with sewage sludge as an organic matrix and tested on an agricultural species that indicates nutrient absorption (corn) and another forestry species (eucalyptus).