In this paper, a systematic approach to design a number of optimal fuzzy linear quadratic regulators for discrete-time affine takagi-sugeno (T-S) models is proposed. T-S fuzzy models in which local dynamics in different state-space regions are represented explicitly by linear models with bias term are considered. We provide a systematic construction procedure for discrete-time T-S affine fuzzy controllers, based on the parallel distributed compensation technique. Finally, the optimal fuzzy control is applied to a biological wastewater treatment process in order to illustrate the effectiveness of the proposed approach.