Abstract
New alternatives for alcohol production from low-cost feedstocks, such as lignocellulosic biomasses, have been proposed. Banana wastes are an example of these substrates. Existing applications involve the use of the fruit, leaves and other residues, such as the pseudostem. Centrifugation is commonly used for the separation of the solids in the fermentation broth. However, due to the presence of banana residues in the broth, it is necessary to evaluate whether the solid-liquid separation method interferes with the composition of the clarified broth (wine) that is sent to ethanol recovery by distillation. Based on this scenario, the objective of this study was the characterization of the liquid and solid phases for three separation methods: centrifugation, vacuum filtration and microfiltration. Centrifugation was performed at 3800 rpm.min-1 for 20 min and vacuum filtration was conducted with the fermentation broth poured through a filter paper in a Buchner funnel. Microfiltration was performed using a capillary membrane module (polyimide) at room temperature with a flow rate of 90 L.h-1. The loss of ethanol in the liquid phase was evaluated for each method; no differences among the methods were observed. Few differences in the clarified broth composition were verified after centrifugation compared with vacuum filtration and microfiltration. For the removal of solids, microfiltration resulted in a minor presence of total solids in the liquid. These results support microfiltration as a potential method for the separation of solids and liquids in fermentation broth from banana waste. Similarly, the moisture content, Chemical Oxygen Demand (COD), Total Nitrogen (TN) and pH were determined for the solid phase that was discarded after the separation. The highest COD and moisture contents and the lowest value of TN were obtained with microfiltration. The solid residue should be characterized with respect to other constituents and properties to assess their use in processes such as biogas production.
