Reaproveitamento do lodo de esgoto sanitário em solo do cerrado: efeitos ecotoxicológicos em plantas

Abstract

The use of natural resources has directly accompanied population growth, and as a result, sustaining modern life depends on various production chains that continuously consume resources to ensure the supply of products and services demanded by society. In this context, the basic sanitation process, which ensures the treatment of domestic effluents for safe return to the environment, generates a residue known as sewage sludge (SS). This residue is commonly disposed of in landfills, posing a significant environmental liability, despite its potential for reuse when subjected to proper stabilization processes. The aim of this study is to evaluate the ecotoxicological effects of sewage sludge (SS) from the Uberabinha Sewage Treatment Plant in the city of Uberlândia, Minas Gerais, assessing its potential to cause negative impacts on the environment and the possibility of reuse as an agricultural input. Both the potential of SS to cause negative environmental impacts and its potential for reuse as an agricultural input were observed. In this context, the processes of reducing the toxicity of this residue through chemical stabilization (CS) with hydrated lime (CaOH2), natural attenuation (NA), and phytoremediation using cedar rose (Cedrela fissilis), a native cerrado species, were also evaluated. Through these processes, it was observed that CS, despite its proven effectiveness for stabilization for agricultural purposes, can lead to secondary toxicity effects in bioassays with lettuce (Lactuca sativa) and onion (Allium cepa) seeds, as well as phytoremediation, due to the physicochemical and biological interactions occurring in the rhizospheric soil. This emphasizes the need for continuous monitoring of the toxicity curve of the residue over time using chemical and biological indicators. As for the NA process, it was sufficient for attenuating the toxicity of SS, preventing it from causing effects on phytotoxicity, cytotoxicity, genotoxicity, and mutagenicity indicators of the species used. The search for alternatives in SS management is crucial but should always be approached with caution, considering the long-term effects that may result from its application for any purpose. The highly variable characteristics of its composition require constant monitoring and follow-up for successful reuse.