Temperature and pH control in composting of coffee and agricultural wastes

One of the by-products of instant coffee production is a solid waste with high organic content. This waste is disposed of either by landfill sites or by burning as fuel. Both alternatives are considered economically and environmentally unsatisfactory due to the physico-chemical characteristics of the waste. This study investigates the applicability of the forced aeration composting process to a mixture of this coffee waste and agricultural wastes. Approximately 40 tons of waste was used to set up the static piles. Temperature was used as the main parameter to enable control of the aeration rate. Other parameters used to monitor the process were humidity, pH and carbon/nitrogen ratio. The results obtained were satisfactory and the experiments lead to the production of a high quality compost presenting a carbon/nitrogen ratio of the order of 131 to 151.