BIOSTIMULATION OF FILTER CAKE BY RICE HUSK: ECOTOXICITY AND POTENTIAL IN ECOLOGICAL RESTORATION

Abstract

Brazil is one of the largest agricultural producers in the world and, as a result, stands out in the significant generation of agro-industrial waste, which is usually incorrectly disposed of. One of these massively generated residues is filter cake (FC), a mixture of decantation sludge and sugarcane bagasse, which presents high levels of organic matter and minerals. However, when applied in natura as a biofertilizer, it causes environmental damage due to its toxicity. Thus, in order to mitigate this effect and provide an ecological and profitable destination for this waste, this project aims to: develop an efficient, sustainable, and low-cost technology for the detoxification of FC, from a biostimulation process with rice husk; to characterize the FC, isolated and in association with soil and/or rice husk, regarding its phytotoxic, cytotoxic, genotoxic and mutagenic effects; to evaluate the toxicological safety of the final product, obtained after biostimulation of FC, through ecotoxicogenetic assays with Allium cepa (Amaryllidaceae); to test the efficiency of rice husk as a biostimulating agent for FC bioremediation processes. Rice husk, another agro-industrial residue, increases soil porosity, increasing local microbial activity and, consequently, the biodegradation of toxic FC substances. The A. cepa bioassay will be used to monitor toxicity levels for 0, two and four months, evaluating the germination index; changes in the Mitotic Index (MI); presence of chromosomal, nuclear abnormalities and micronuclei in meristematic and F1 region cells. In this sense, it is expected to obtain a material with better nutritional properties and with greater added value, in order to contribute to environmental sustainability and the management of these residues.