Mixing design for enzymatic hydrolysis of sugarcane bagasse: methodology for selection of impeller configuration

• Published in: Bioprocess and biosystems engineering 2016-02, Vol.39 (2), p.285-294
• Main Authors: Corrêa, Luciano Jacob, Badino, Alberto Colli, Cruz, Antonio José Gonçalves
• Format: Article
• Language: English
• Subjects: Bagasse; Biodiesel fuels; Bioengineering; Biotechnology; Cellulose; Cellulose - chemistry; Chemistry; Chemistry and Materials Science; cost effectiveness; energy efficiency; Environmental Engineering/Biotechnology; enzymatic hydrolysis; Enzymes; Ethanol; Food Science; glucose; Hydrolases - chemistry; Hydrolysis; Impellers; Industrial and Production Engineering; Industrial Chemistry/Chemical Engineering; Industrial production; Mass transfer; mixing; Models, Chemical; Original Paper; Power consumption; Reactors; rheological properties; Rheology; rheometers; Saccharum - chemistry; Sugarcane; sugarcane bagasse; Turbines
• ISSN: 1615-7591; 1615-7605
• DOI: 10.1007/s00449-015-1512-6

One of the major process bottlenecks for viable industrial production of second generation ethanol is related with technical–economic difficulties in the hydrolysis step. The development of a methodology to choose the best configuration of impellers towards improving mass transfer and hydrolysis yield together with a low power consumption is important to make the process cost-effective. In this work, four dual impeller configurations (DICs) were evaluated during hydrolysis of sugarcane bagasse (SCB) experiments in a stirred tank reactor (3 L). The systems tested were dual Rushton turbine impellers (DIC1), Rushton and elephant ear (down-pumping) turbines (DIC2), Rushton and elephant ear (up-pumping) turbines (DIC3), and down-pumping and up-pumping elephant ear turbines (DIC4). The experiments were conducted during 96 h, using 10 % (m/v) SCB, pH 4.8, 50 °C, 10 FPU/gbᵢₒₘₐₛₛ, 470 rpm. The mixing time was successfully used as the characteristic parameter to select the best impeller configuration. Rheological parameters were determined using a rotational rheometer, and the power consumptions of the four DICs were on-line measured with a dynamometer. The values obtained for the energetic efficiency (the ratio between the cellulose to glucose conversion and the total energy) showed that the proposed methodology was successful in choosing a suitable configuration of impellers, wherein the DIC4 obtained approximately three times higher energetic efficiency than DIC1. Furthermore a scale-up protocol (factor scale-up 1000) for the enzymatic hydrolysis reactor was proposed.