Configuration modification of a submerged membrane reactor for enzymatic hydrolysis of cellulose

In this study, a modified submerged membrane reactor was investigated as a new configuration for efficient enzymatic cellulose hydrolysis. From the results, effectiveness of ultrafiltration was increased due to the complete glucose permeation and enzyme retention up to 80%. Intermittent product removal at 50% volume replacement was better because it was able to regain the glucose concentration after ultrafiltration and minimised the over-dilution as occurred with the continuous product removal. Results obtained from response surface design showed the quadratic cellulose concentration (A2), the enzyme to substrate ratio (B) and interaction (AC) of cellulose concentration with intermittent product removal were identified to be the significant factors to maximise the glucose concentration. The maximised glucose concentration (7.6 g/L) was obtained at the optimal conditions (10% cellulose concentration, 6% E/S ratio and 50% intermittent product removal). The retained enzyme could be reused to extend hydrolysis beyond 8 h as the glucose concentration was maintained at 7 g/L with an insignificant reduction. Thus, the modified submerged membrane reactor in this new configuration could be an alternative for the conventional batch reactor used in the enzymatic hydrolysis.