Kinetic modelling of yeast growth and pollutant removal in secondary effluent. (December 2022)

• Record Type: Journal Article
• Authors: Mohiuddin, Obaidullah; Harvey, Adam P; Tabraiz, Shamas; Ameen, Muhammad Tahir; Velasquez-Orta, Sharon
• Is Part Of: Journal of water process engineering. Volume 50(2022)
• Publication Date: 2022-12
• Subjects: Monod -- Kinetic modelling -- Wastewater treatment -- Yeast growth -- Pollutant consumption; COD Chemical oxygen demand, mg.L−1 -- μ Specific growth rate, h−1 -- μmax Maximum specific growth rate, h−1 -- KC Half-saturation constant for carbon, mg.L−1 -- KN Half-saturation constant for nitrogen, mg.L−1 -- KP Half-saturation constant for phosphorus, mg.L−1 -- KCapp Apparent half-saturation constant for carbon, mg.L−1 -- KNapp Apparent half-saturation constant for nitrogen, mg.L−1 -- KPapp Apparent half-saturation constant for phosphorus, mg.L−1 -- Co Initial concentration of carbon, mg.L−1 -- No Initial concentration of nitrogen, mg.L−1 -- Po Initial concentration of phosphorus, mg.L−1 -- C Concentration of carbon, mg.L−1 -- N Concentration of nitrogen, mg.L−1 -- P Concentration of phosphorus, mg.L−1 -- Yeasti Initial Concentration of yeast, mg.L−1 -- k Reaction constant (1st or 2nd Order) -- X Biomass concentration -- dx/dt Rate of change of biomass production -- dS/dt Rate of change of substrate consumption -- TSS Total suspended solid, mg.L−1 -- YC Carbon removal coefficient, mgC/mg.yeast -- YN Nitrogen removal coefficient, mgN/mg.yeast -- YP Phosphorus removal coefficient, mgP/mg.yeast; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2022.103244
• Languages: English
• ISSNs: 2214-7144

Abstract

Abstract: In recent years, there has been significant interest in yeast-based wastewater treatment due to its high pollutant removal rate and ability to perform in non-sterile environments. In this work, a kinetic model was developed to predict yeast growth and substrate consumption during wastewater treatment. To determine the biological constants for use in the kinetic models, a unique approach is presented. Candida utilis was cultivated in synthetic wastewater, using eight different ratios of carbon, nitrogen and phosphorus to determine its growth rate, and the removal rates of carbon, nitrogen, and phosphorus. The concentrations of C, N and P were chosen within the range of secondary effluent wastewater. In all experiments, carbon was found to be the limiting substrate, and 100 % TOC removal was achieved in all cases. Candida utilis reduced the COD concentration by up to 99 % in <24 h. In the model, both yeast growth and substrate consumption were satisfactorily described by Monod kinetics. The apparent half-saturation coefficients for carbon, nitrogen, and phosphorus, determined via the optimization of the model, were found to the function of initial substrate concentration. The maximum specific growth rate found was 0.59 h −1 . This model was used on different initial concentrations of substrates, and predicted data with an R 2 above 80 %. Both model and experimental results suggest that Candida utilis can be used in the tertiary treatment of wastewater. The simple approach described here can be applied to find biological coefficients for other microorganisms. Highlights: A mathematical approach is presented to determine the biological constant for multi-substrate Monod kinetics. Half-saturation is not constant but is dependent upon the initial concentration of substrates. Change in pH does not affect the relation of the half-saturation coefficient to initial substrate concentration. Only the substrate removal coefficient/Yield coefficient varies with respect to pH.