The applicability of the mixed bacterial culture, originated from two-stage anaerobic-aerobic industrial yeasts production wastewater treatment plant for high rate denitrification processes was investigated. After acclimation to nitrate, the dominant strains were Pseudomonas and Paracoccus sp. Complete denitrification with low accumulation of nitrite-N (0.1 mg/l) was found in synthetic wastewater, obeying a zero-order reaction with respect to nitrate and a first-order reaction with respect to biomass concentration. Denitrification was then monitored in the continuous-flow stirred reactor at different hydraulic retention time, HRT (62-28h) in order to achieve the optimal HRT. Nitrate was completely removed during following 45days, at 25degreesC with HRT, which we reduced from 62 to 28h. Yet still, at 28h HRT, high average specific denitrification rate of 142 mg NO3--N/g VSS h was obtained. (C) 2004 Elsevier Ltd. All rights reserved.