Sewage sludge is a residue resulting from the wastewater treatment process. Due to its increasing production and toxic composition, its correct management is essential to avoid harmful effects on the environment. Among the possible alternatives for a more sustainable destination for this residue, there is its use as a conditioner of agricultural soils due to the possibility of reusing its nutrients, since it is rich in organic matter, phosphorus, nitrogen, and micronutrients. However, the presence of toxic substances can make this practice unfeasible. The present project aims to develop low-cost technologies for the detoxification of sewage sludge that allow its use as an agricultural additive. For this, sludge samples will be submitted to the biostimulation process, using rice husk as a bulking agent, and to the bioaugmentation process, through the incorporation of the edible fungus Pleurotus ostreatus (shimeji). Mixtures containing sludge and soil (3:1 - v/v); sludge, soil, and rice husk (3:1:1 - v/v/v); sludge, soil, and inoculum (3:1 - v/v); and sludge, soil, rice husk and inoculum (3:1:1- v/v/v), in addition to pure sludge, will be placed in stainless steel vats and kept in a covered place at room temperature for periods of 0, 3 and 5 months. The efficiency of these strategies will be evaluated through the bioassay with Allium cepa. The toxic effect will be verified by the inhibition of seed germination. The cytotoxic action will be evaluated through alterations in the mitotic index. The genotoxic potential will be verified from the quantification of chromosomal aberrations and nuclear abnormalities. The mutagenicity will be evaluated by the presence of micronuclei in cells of the F1 region. In this way, it is expected to obtain important results for the problem of the disposal of the LE, from the use of bioremediation technologies that promote the transformation of this environmentally impacting waste, into a material with added value for agricultural purposes (organic fertilizer) and with a guarantee of safety in terms of environmental toxicity.
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