Faculty Publications
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Item Calorespirometric investigation of Streptococcus zooepidemicus metabolism: Thermodynamics of anabolic payload contribution by growth and hyaluronic acid synthesis(Elsevier B.V., 2019) Mohan, N.; Allampalli, S.S.; Achar, A.; Swaminathan, N.; Sivaprakasam, S.Thermodynamic analysis of carbon flux competing for pathways of S. zooepidemicus in the production of catabolic (Lactic acid) and anabolic (Biomass and Hyaluronic Acid) products is investigated to assimilate the thermodynamic advantages of biopolymer production. Calorespirometry was employed to fingerprint the on-going HA production process and to predict reliable estimation of catabolic and anabolic product yields. This study accomplished the HA production at different initial glucose concentrations, S0 (10–60 g/L) to subject different levels of anabolic burden on S. zooepidemicus. Anabolic payload comprising Biomass and HA yields showed a concomitant decrease with respect to the increased concentration of S0. Chemical entropy exported over the cell surface in the form of LA production exhibited an increasing trend at different levels of glucose, thus reducing the total yields of biomass and HA. Thermodynamically anabolic load contributed by biomass and HA production found to have minor influence over the driving force of S. zooepidemicus metabolism due to their lower yields. The entropy contribution to the overall driving force is significant (T?SX= [Formula presented] ?rGX) at the higher biomass yields. This study allows the prediction of optimum biomass yield towards enhanced HA production and addresses the scope of ‘thermodynamic constraints’ application in real-time process monitoring and control using data reconciliation strategy in the near future. © 2019 Elsevier B.V.Item Residence Time Distribution Studies in a Modified Rotating Packed Disc Contactor: Mathematical Modeling and Validation(De Gruyter Open Ltd, 2020) Kalnake, R.P.; Murthy, D.V.R.; Achar, A.; Raval, K.A modified rotating packed disc contactor (RPDC) with the maximum working volume of 65 liter is designed for biological waste water treatment. A hollow disc with radial vanes mounted on the disc was a modified design of this contactor. Stimulus-response experiments were conducted in the contactor to understand liquid mixing behavior under different operating conditions. The recycle stream was also used in the operation of the contactor. Experiments were conducted for different number of discs, rotational speeds and recycle ratios. The disc design and recycle ratio had marked influence on the mixing behavior. An increase in disc rotation and recycle ratio produced a well-mixed flow behavior. Moreover, the surface area available in the RPDC was about 4 times more than the surface area available in a standard rotating biological contactor (RBC) operating at similar conditions. A mathematical model was developed for the flow behavior under recycle and a good agreement was found between the model and experimental results. © 2020 Walter de Gruyter GmbH, Berlin/Boston 2020.