An integrated hydrodynamic-biokinetic model to optimize the treatment processes in a laboratory-scale, pilot-scale, and full-scale bioreactor. (October 2022)

• Record Type: Journal Article
• Authors: Mohan, T. Reshma; Kumar, M.S. Mohan; Rao, Lakshminarayana
• Is Part Of: Journal of water process engineering. Volume 49(2022)
• Publication Date: 2022-10
• Subjects: Bioreactor -- Computational fluid dynamics -- Population balance model -- Activated sludge model 1 -- Combined EPS-SMP model; Water-supply engineering -- Periodicals; Saline water conversion -- Periodicals; Seawater -- Distillation -- Periodicals; Sanitary engineering -- Periodicals; Sewage -- Purification -- Periodicals; 627
• DOI: 10.1016/j.jwpe.2022.103108
• Languages: English
• ISSNs: 2214-7144

Abstract

Abstract: One major disadvantage of membrane bioreactors (MBRs) is the high operating and aeration costs, and optimizing the process to attain economic efficiency is essential. In this study, a hydrodynamic - biokinetic integrated model was developed by combining a multiphase computational fluid dynamics (CFD) model with a population balance (PBM) submodel, an activated sludge (ASM1) submodel, and a combined (EPS – SMP) CES submodel. The developed integrated model was used to investigate the efficiency of treatment of bioreactors on three different scales (case 1 - laboratory, case 2 – pilot, and case 3 - full-scale system). The simulated values of bubble size count, total chemical oxygen demand (TCOD), total nitrogen (TN), ammonical nitrogen (SNH ), nitrate‑nitrogen (SNO ), EPS, and SMP concentrations were well validated with the experimental results, with an error percentage of 2.8 %, 6.32 %, 2.25 %, 0.53 %, 1.19 %, 4.62 %, and 2.05 %, respectively. The validated model is then extended for sensitivity analysis to identify optimum conditions (H/B ratio, H/S ratio, and bubble size) to reduce TCOD and TN concentration. The maximum percentage reduction in TCOD and TN concentrations in the most optimum scenario was 20 and 23 %, respectively, for case 3 . Also, a reduction of 32 % in the cost of aeration was observed (for case 3 ) when the bubble size was reduced to 5 mm (from the current value of 7 mm). The preceding results suggest that the integrated model successfully optimized the treatment processes. Highlights: CFD–PBM–ASM1-CES integrated model was developed and validated in bioreactors. Optimum bubble size was found to be 5 mm, giving the minimum TCOD and TN values. Optimum H/B and H/S ratios were found as 23 & 2.5 for pilot and full-scale reactors. After optimization, the maximum reduction in TCOD and TN values were 74 and 5 mg/L. A 32 % reduction in aeration cost was observed by reducing the bubble size to 5 mm.