Spent Coffee Grounds Characterization and Reuse in Composting and Soil Amendment

Abstract

As an everyday beverage, coffee is consumed worldwide, generating a high amount of waste after brewing, which needs attention for its disposal. These residues are referred to as spent coffee grounds (SCGs), which have been shown to have applications as polymers/composites precursors, biofuels, and biofertilizers. This review focuses on agricultural applications usually based on organic matter to fertilize the soil and consequently improve plant growth. To date, SCGs have been shown to exhibit outstanding performance when applied as soil amendment and composting because it is a nutrient-rich organic waste without heavy metals. Therefore, this review presents the different options to use SCGs in agriculture. First, SCG composition using different characterization techniques is presented to identify the main components. Then, a review is presented showing how SCG toxicity can be resolved when used alone in the soil, especially at high concentrations. In this case, SCG is shown to be effective not only to enhance plant growth, but also to enhance nutritional values without impacting the environment while substituting conventional fertilizers. Finally, a conclusion is presented with openings for future developments.

Study on Physicochemical Properties of Biocomposite Films with Spent Coffee Grounds as a Filler and Their Influence on Physiological State of Growing Plants

“…It is worth highlighting that cf contain ca. 1.8-2.8% nitrogen [16,19] from, e.g. proteins and caffeine.…”

The Potential of Spent Coffee Grounds in Functional Food Development

“…Degradation products during roasting include the carcinogen, acrylamide; practical solutions to reduce acrylamide production were proposed [ 33 ]. The SCG remaining after production of hot-brew coffee include carbohydrates such as 8–15% celluloses and 30–40% hemicelluloses, 20–30% lignins, 7–21% lipids and minerals, and 13–17% proteins, together with phenolic compounds (12 mg/g), caffeine (14.5 µg/g) and CGA (31.8 µg/g) [ 34 ]. Further, isolation and characterisation of these components were reviewed [ 34 ].…”

“…The SCG remaining after production of hot-brew coffee include carbohydrates such as 8–15% celluloses and 30–40% hemicelluloses, 20–30% lignins, 7–21% lipids and minerals, and 13–17% proteins, together with phenolic compounds (12 mg/g), caffeine (14.5 µg/g) and CGA (31.8 µg/g) [ 34 ]. Further, isolation and characterisation of these components were reviewed [ 34 ]. Similar information on SCG produced after cold-brew extraction processes is not available.…”

Unveiling the Potential of Coffee Grounds, Banana Peels and Egg Shells as an Eco‐Friendly and Sustainable Fertilizer

“…The analysis revealed that all eggshells exhibited consistent chemical composition, primarily composed of CaCO3, along with trace amounts of other elements such as S, Mg, P, Al, K, and S. [15] Minerals constitute a portion of the chemical composition of coffee grounds, where the most prevalent minerals extracted from coffee grounds include potassium, phosphorus, magnesium, and calcium. [16][17][18][19] The diverse array of nutrient-rich compounds extracted from coffee grounds [20] banana peels and egg shells can potentially offer a multitude of applications, particularly in the field of agriculture as fertilizers.…”

“…Minerals constitute a portion of the chemical composition of coffee grounds, where the most prevalent minerals extracted from coffee grounds include potassium, phosphorus, magnesium, and calcium. [ 16–19 ] The diverse array of nutrient‐rich compounds extracted from coffee grounds [ 20 ] banana peels and egg shells can potentially offer a multitude of applications, particularly in the field of agriculture as fertilizers.…”