TRANSFORMATION OF COFFEE WASTE INTO BIOCHAR: A SUSTAINABLE SOLUTION

Abstract

The present study aimed to produce biochar from coffee husks through slow pyrolysis and to evaluate its chemical and structural properties, as well as its effects on the physicochemical characteristics of soil cultivated with Allium schoenoprasum. The biochar was obtained in a muffle furnace at 300 °C, with an average conversion rate of 78.61%. Different particle sizes (150 and 300 mesh) and concentrations (1%, 2%, and 3% w/w) were tested. Laboratory analyses showed that the application of biochar increased soil pH and base saturation, enhanced cation exchange capacity (CEC), and improved the retention of nutrients such as potassium, calcium, magnesium, and phosphorus compared to soil without biochar. Physical analysis revealed an increase in clay and fine sand fractions, resulting in greater water retention capacity. Visually, a more vigorous growth of chives plants and a lower incidence of pests were observed in pots treated with biochar. From an environmental standpoint, the biochar exhibited a porous and stable structure, with potential to act as a carbon sink, contributing to the mitigation of greenhouse gas emissions. Therefore, the use of coffee husk biochar proves to be a sustainable alternative for agricultural waste management and soil fertility improvement, aligning with the Sustainable Development Goals (SDGs 12, 13, and 15) and the global targets of circular economy and low-carbon development.

DOI: https://doi.org/10.56238/sevened2026.001-031