Cyanogenic Residues: Environmental Impacts, Complexation with Humic Substances, and Possible Application as Biofertilizer

The disposal of cyanogenic residues from the processing of cassava, during the flour production in certain regions of the Brazilian northeastern, has been a cause of concern in recent years, since this practice may lead to environmental imbalances. The results obtained in this work show a possible impact caused by the release of this kind of waste into water bodies, as well as its potential use as biofertilizer, mainly due to its high nutrient content. Humic substances (HS) from water and soil showed high interaction with cyanide ions (CN-), being the main responsible for the bioavailability of these ions into the environment. Furthermore, studies in microcosms propose viable and low-cost alternatives to decrease the levels of CN- ions in the liquid waste (called manipueira), as well as its potential use as biofertilizer.