LEANDRO GOULART DE ARAUJO
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Artigo IPEN-doc 29635 Prospects for fungal bioremediation of unburied waste packages from the Goiânia radiological accident2023 - TESSARO, ANA P.G.; ARAUJO, LEANDRO G. de; SILVA, THALITA T.; COELHO, EDNEI; CORREA, BENEDITO; ROLINDO, NATALIE C.; VICENTE, ROBERTOGoiânia, the Goiás State capital, starred in 1987, where one of the largest radiological accidents in the world happened. A teletherapy machine was subtracted from a derelict radiotherapy clinic and disassembled by scavengers who distributed fragments of the 50 TBq 137CsCl source among relatives and acquaintances, enchanted by the blue shine of the substance. During the 15 days before the accident was acknowledged, contaminated recycling materials were delivered to recycling factories in four cities in the state of São Paulo, Brazil, in the form of recycling paper bales. The contaminated bales were spotted, collected, and stored in fifty 1.6 m3 steel boxes at the interim storage facility of the Nuclear and Energy Research Institute (IPEN). In 2017, a check of the content was performed in a few boxes and the presence of high moisture content was observed even though the bales were dry when conditioned and the packages were kept sealed since then. The main objective of this work was to report the fungi found in the radioactive waste after they evolved for 30 years in isolation inside the waste boxes and their role in the decay of the waste. Examination of the microbiome showed the presence of nematodes and fungal communities. The fungi species isolated were Aspergillus quadricinctus, Fusarium oxysporum, Lecanicillium coprophilumi, Scedosporium boydii, Scytalidium lignicola, Xenoacremonium recifei, and Pleurostoma richardsiae. These microorganisms showed a significant capacity to digest cellulose in our trials, which could be one of the ways they survive in such a harsh environment, reducing the volume of radioactive paper waste. These metabolic abilities give us a future perspective of using these fungi in biotechnology to remediate radioactively contaminated materials, particularly cellulose-based waste.Artigo IPEN-doc 29048 Uranium biosorption by hydroxyapatite and bone meal2022 - WATANABE, TAMIRES; GUILHEN, SABINE N.; MARUMO, JULIO T.; SOUZA, RODRIGO P. de; ARAUJO, LEANDRO G. deBiosorption has been examined for the treatment of aqueous solutions containing uranium, a radiotoxic pollutant. Nevertheless, the evaluation of the role of process variables by experimental design on the use of hydroxyapatite and bone meal as biosorbents for uranium has not yet been previously addressed. In this study, the effects of adsorbent dosage (M), initial uranium concentrations ([U]0), and solution pH were investigated, using a two-level factorial design and response surface analysis. The experiments were performed in batch, with [U]0 of 100 and 500 mg L−1, pH 3 and 5, and adsorbent/uranium solution ratios of 5 and 15 g L−1. Contact time was fixed at 24 h. Removal rates were higher than 88%, with a maximum of 99% in optimized conditions. [U]0 and M were found to be the most influential variables in U removal in terms of adsorption capacity (q). The experiments revealed that bone meal holds higher adsorption capacity (49.87 mg g−1) and achieved the highest uranium removal (~ 100%) when compared to hydroxyapatite (q = 49.20 mg g−1, removal = 98.5%). The highest value of q for both biomaterials was obtained for [U]0 = 500 mg L−1, pH 3, and M = 5 g L−1. Concerning the removal percentage, bone meal achieved the best performance for [U]0 = 500 mg L−1, pH 3, and M = 15 g L−1. Further experiments were made with real radioactive waste, resulting in a high uranium adsorption capacity for both materials, with 22.11 mg g−1 for hydroxyapatite and 22.08 mg g−1 for bone meal, achieving uranium removal efficiencies higher than 99%.