Valorization of Coffee Waste for Wastewater Treatment and Fertilizer Products

Abstract

Current mainstream fertilizers are disruptive to the environment. This includes pollution, soil quality degradation, and even air pollution. Alternative methods for supplying nutrients to plants is important, as there is a high demand for improving crop yields to sustain the growing population. Spent coffee grounds are rich in C, N, and K which makes them a viable option for fertilizer applications as they would improve soil quality through the addition of organic matter. Additionally, spent coffee grounds are in abundance due to the high consumption of coffee globally. This would lead to less waste coffee entering the landfill, which would in turn reduce greenhouse gas emissions by reducing the rate at which coffee grounds are sitting decomposing in a landfill. In addition to spent coffee grounds improving soil quality, minerals can be crystallized onto the surface of the coffee grounds in order to target the essential nutrients for plant growth. Struvite was selected, since it contains many elements that aid in photosynthesis in plants, but it is also a byproduct in wastewater treatment and management. Therefore, functionalizing the coffee grounds with PEI for metal ion removal, and GMAC for bacterial inactivation to aid in the treatment of wastewater enables a system to be created that starts with the decontamination of wastewater, and can act as a slow-release fertilizer.