Use of by-products generated in the processing of coffee berries: A review

Abstract

Coffee production plays an essential role in the Brazilian economy, and a large production centre is located in Minas Gerais. In recent years, there has been an increase in coffee cultivation, consequently generating coffee wastewater (CW) and solid waste (skin, pulp, parchment, and dregs) during the processing stage. Thus, the present review study seeks to characterize these by-products from the coffee production chain and present their possible applications in agribusiness and other sectors towards a circular economy, mainly related to reuse as fertilizer or energy and biomaterial recovery. CW treatment is complex given the high concentrations of organic matter, phenols, and nutrients, especially potassium. Still, its use as a liquid fertilizer is highly recommended as it can increase crop yield. In this regard, CW should be applied to soil according to nutritional criteria, with potassium as the reference chemical element. The wastewater production and its potential for soil contamination can be reduced by applying biological, physical, or chemical treatment along with recirculation routes during the washing/peeling/pulping of coffee berries. Moreover, the solid waste from coffee production can be used for energy generation, wastewater treatment (as an organic filter material or biochar), and as organic fertilizer (in natura or composted).