Feasibility of compost production with coffee husk

Abstract Coffee is one of the most consumed beverages in the world. In 2014, the globally consumption of coffee was 149 million bags of coffee, and approximately 17.8 bil-lion packages of coffee bought in common food stores. Coffee husk (a by-product of roasting) is generated from coffee processing station and is disposed in landfills or into arable land usually with no care on its fate. Instead, an environmental friendly method is needed to re-use a product that may give good agronomic re-plies. The treatment of coffee husk through oxygen-driven biological methods such as composting, would serve a dual purpose: fertilizer production and environmental protection. In addition, analysis showed that coffee husk is rich in organic matter (cellulose, hemicelluloses, pectins, and lignins), chemical nutrients such as N and K, and secondary compounds such as caffeine, tannins and polyphenols. The topic of this study was to evaluate the possibility to produce efficient composts with lone coffee husk (Pile 1), coffee husk and brewers grain in proportion of 2:1 (Pile 2), coffee husk and cow manure with ratio of 4:1 (Pile 3), and a mixture of coffee husk, brewers grain and cow manure with the ratio of 5:3:2, respectively (Pile 4). Every pile was around 300 kg. All piles were covered with a plastic in order to prevent excessive moisture loss and preserved in greenhouse. The composting method is aerated static pile composting, and the humidity of the materials is around 60%. Samples from each pile (about 500 g each) were collected separately on days 0, 30, 60, and 90 and immediately stored at -20 oC upon arrival at the la-boratory for molecular analyses, and at 4 oC for all the other analyses. The chemi-cal parameters checked during 90 days composting were C, N, and biomass C con-tent, total hydrolase activity (FDA test), and the content of several organic acids and alkaloids. The results indicate that coffee husk has an adequate potential for compost production.