Optimization of enzymatic hydrolysis of lignocellulose in a non-ideally mixed reactor is studied in this work. The reactor is divided into 36 compartments connected by circulation and exchange flows, and each compartment is modeled as a well-mixed reactor. Reaction kinetics and heat balance models for batch and fed-batch mode of operation are integrated with the compartmental model for process optimization of a 3 m(3) reactor. Maximization of glucose and profit problems were solved for the batch mode of operation. The glucose concentration and profit improved by 3.19 and 6.63%, respectively, after considering non-ideal mixing. The impact was particularly critical for batch times smaller than 24 h. For fed-batch reactor, a problem maximizing profit while maintaining 10% solid loading using optimal control improved profit by 11.23% when non-ideality in mixing was considered. The results illustrated the value of considering non-ideal mixing in operating the reactors. (C) 2019 Elsevier Ltd. All rights reserved.