Treatment of fish-processing wastewater by co-culture of Candida rugopelliculosa and Brachionus plicatilis

Abstract

This research was conducted as a part of the continuous development of a novel technique for managing fish-processing wastewater by cultivating proteolytic yeast, Candida rugopelliculosa, as possible diet of the rotifer, Brachionus plicatilis. It was feasible to use Alaska Pollack processing wastewater as a growth medium for C. rugopelliculosa, which was stimulatory for growth of the rotifer by 18.3% over the commercial diet of Saccharomyces cerevisiae. Maximum growth of C. rugopelliculosa and reduction of influent soluble chemical oxygen demand (SCOD) concentration were respectively (6.09±0.04)×10 6 cells/ml and 70.0% at 6.3 h hydraulic retention time (HRT). Method of 4th order Runge–Kutta approximation was successfully applied to determine the Monod kinetics of C. rugopelliculosa by using unsteady state data from only one continuous unsteady state operation at a fixed HRT. The maximum microbial growth rates, μ max, and half saturation coefficient, K s, were determined to be 0.82±0.22 h −1 and 690±220 mg SCOD/L, respectively. The microbial yield coefficient, Y, and microbial decay rate coefficient, k d, were determined to be (1.39±0.22)×10 4 cells/mg SCOD and 0.06±0.01 h −1, respectively.