Browsing by Author "Vanapalli, Kumar Raja"

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    Comparative life cycle assessment of glycerol valorization routes to 1,2- and 1,3-propanediol based on process modeling
    (American Chemical Society , 2024-10-07) Vanapalli, Kumar Raja; Nongdren, Lourembam; Maity, Sunil K; Kumar, Vinod
    Crude glycerol, a high-volume byproduct of the biodiesel industry, has seen a significant surplus due to the industry’s rapid growth. It can be a promising feedstock for a range of high-value products via chemical and biochemical routes. This study thus elucidates the relative environmental performance of two prominent glycerol valorization technologies, i.e., catalytic hydrogenolysis to 1,2-propanediol and microbial fermentation (batch and fed-batch) to 1,3-propanediol, using a cradle-to-gate life cycle assessment (LCA). The LCA was performed using an experimental data-driven comprehensive process model to represent an industrial-scale biorefinery, handling 20 833 kg/h of glycerol. The LCA results identified cooling water (18-35.5%) and steam (15.2-33.7%) consumption in the distillation and glycerol sourcing (33.3-68.1%) as the critical environmental hotspots, which should be focused on while designing the process. The fed-batch fermentation process was environmentally more benign, with significantly lower environmental impacts than hydrogenolysis (by 35.2%) and batch fermentation (by 48.2%). Integrating effective process heat recovery using pinch technology reduced the overall environmental impacts by 4.9-11.2%. The environmental performance of the overall processes varied substantially (2.4-62.1%) with changes in glycerol sourcing and production methods. Therefore, energy and material recycling with sustainable water and glycerol sourcing can improve the sustainability of the overall process.
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    Life cycle assessment of fermentative production of lactic acid from bread waste based on process modelling using pinch technology
    (Elsevier, 2023-09-22) Vanapalli, Kumar Raja; Bhar, Rajarshi; Maity, Sunil K.; Dubey, Brajesh K.; Kumar, Sandeep; Kumar, Vinod
    Bread waste (BW), a rich source of fermentable carbohydrates, has the potential to be a sustainable feedstock for the production of lactic acid (LA). In our previous work, the LA concentration of 155.4 g/L was achieved from BW via enzymatic hydrolysis, which was followed by a techno-economic analysis of the bioprocess. This work evaluates the relative environmental performance of two scenarios - neutral and low pH fermentation processes for polymer-grade LA production from BW using a cradle-to-gate life cycle assessment (LCA). The LCA was based on an industrial-scale biorefinery process handling 100 metric tons BW per day modelled using Aspen Plus. The LCA results depicted that wastewater from anaerobic digestion (AD) (42.3–51 %) and cooling water utility (34.6–39.5 %), majorly from esterification, were the critical environmental hotspots for LA production. Low pH fermentation yielded the best results compared to neutral pH fermentation, with 11.4–11.5 % reduction in the overall environmental footprint. Moreover, process integration by pinch technology, which enhanced thermal efficiency and heat recovery within the process, led to a further reduction in the impacts by 7.2–7.34 %. Scenario and sensitivity analyses depicted that substituting ultrapure water with completely softened water and sustainable management of AD wastewater could further improve the environmental performance of the processes.
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    Techno-economic viability of bio-based methyl ethyl ketone production from sugarcane using integrated fermentative and chemo-catalytic approach: process integration using pinch technology
    (Elsevier, 2024-04-24) Varma, Abhishek R.; Shrirame, Bhushan S.; Gadkari, Siddharth; Vanapalli, Kumar Raja; Kumar, Vinod; Maity, Sunil K.
    Butanediols are versatile platform chemicals that can be transformed into a spectrum of valuable products. This study examines the techno-commercial feasibility of an integrated biorefinery for fermentative production of 2,3-butanediol (BDO) from sucrose of sugarcane (SC), followed by chemo-catalytic upgrading of BDO to a carbon-conservative derivative, methyl ethyl ketone (MEK), with established commercial demand. The techno-economics of three process configurations are compared for downstream MEK separation from water and co-product, isobutyraldehyde (IBA): (I) heterogeneous azeotropic distillation of MEK-water and extractive separation of (II) MEK and (III) MEK-IBA from water using p-xylene as a solvent. The thermal efficiency of these manufacturing processes is further improved using pinch technology. The implementation of pinch technology reduces 8% of BDO and 9–10% of MEK production costs. Despite these improvements, raw material and utility costs remain substantial. The capital expenditure is notably higher for MEK production from SC than BDO alone due to additional processing steps. The extraction based MEK separation is the simplest process configuration despite marginally higher capital requirements and utility consumption with slightly higher production costs than MEK-water azeotropic distillation. Economic analysis suggests that bio-based BDO is cost-competitive with its petrochemical counterpart, with a minimum gross unitary selling price of US$ 1.54, assuming a 15% internal rate of return over five-year payback periods. However, renewable MEK is approximately 16–24% costlier than the petrochemical route. Future strategies must focus on reducing feedstock costs, improving BDO fermentation efficacy, and developing a low-cost downstream separation process to make renewable MEK commercially viable.