Ecotoxicity and biostimulation of sewage sludge with orange peel to obtain sustainable organic fertilizer

Abstract

Sewage sludge is a semi-solid residue resulting from the wastewater treatment process. Due to its increasing production and toxic composition, it is essential to manage it properly to avoid harmful effects on the environment. Among the options for a sustainable disposal, its use as a fertilizer and/or agricultural conditioner stands out for improving the physical, chemical and biological characteristics of the soil, since the sludge is rich in organic matter, phosphorus, nitrogen and micronutrients. However, the presence of toxic contaminants in the sludge can make this practice unfeasible. In order to mitigate this effect and offer a sustainable destination for this waste, this project aims to develop a low-cost technology for the detoxification of sewage sludge. Thus, sludge samples will be submitted to the bioremediation process by biostimulation with orange peel waste, which will act as a decompacting agent and will contribute to microbial growth by incorporating additional nutrients. The bioassay with Allium cepa will be used to evaluate the efficiency of the bioremediation, characterizing the toxicity of this residue in the different tested periods. The phytotoxic, cytotoxic, genotoxic and mutagenic effects will be evaluated through the seed germination index, alterations in the mitotic index, chromosomal alterations and nuclear abnormalities in meristematic cells and the presence of micronucleus in cells of the F1 region. Therefore, it is expected to obtain important results for the problem of sludge disposal through technologies that promote the transformation of this residue into a material with added value and with a guarantee of safety, in terms of environmental toxicity.