Chemical coagulation of coffee wastewater for smallholder coffee agro-industry

Abstract

Water minimization for processing Robusta coffee has improved the green coffee quality. However, this approach leads to increase color and organic matter concentrations in the downstream process. In this study, different chemical coagulations were proposed to reduce color and organic matter (measured as chemical oxygen demand, COD) contained in the coffee wastewater. This study aimed to determine the optimum coagulant dose and operating pH conditions. Two commonly used and inexpensive coagulants, i.e. Al2(SO4)3 and FeCl3 were evaluated. Samples were collected from smallholder coffee processing. The best performance was achieved by adding 7,5 g/L of FeCl3 at pH 5 with the removal of COD and color was 71,9% and 97,8%, respectively. Yet, resulted final effluent with low pH means new problem for disposal.