Browsing by Author "Kumar, Sandeep"

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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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    Modeling the production of microalgal biomass in large water resource recovery facilities and its processing into various commodity bioproducts
    (MDPI, 2023-10-16) Pierson, James; Makkena, Gopi Raju; Kumar, Sandeep; Kumar, Vinod; Vivekanand, Vivekanand; Husain, Hasan; Ayser, Muhammad; Balab, Venkatesh
    Algae are capable of sequestering nutrients such as nitrates and phosphates from wastewater in the presence of sunlight and carbon dioxide (CO2) to build up their body mass and help combat climate change. In the current study, we carried out different case studies to estimate the volume of algal biomass that could be produced annually using the rotating algal biofilm (RAB) method in three large-scale water resource recovery facilities (WRRFs) in Texas: Fort Worth, Dallas, and Houston. We calculated the total amount of lipids, carbohydrates, and proteins that could be fractionated from the algal biomass while using the hydrothermal flash hydrolysis process, followed by converting these biomolecules into commodity products via reported methods and yields. In the first case study, we estimated the amount of biogas and electricity produced in anaerobic digesters when the algal biomass and sludge generated in large-scale WRRFs are co-digested. Using this approach, electricity generation in a large-scale WRRF could be increased by 23% and CO2 emissions could be further reduced when using biogas combustion exhaust gases as a carbon source for the RAB system. In the second case study, it was estimated that 988 MT mixed alcohol or 1144 MT non-isocyanate polyurethane could be produced annually from the protein fraction in the WRRF in Fort Worth, Texas. In the third case study, it was estimated that 702 MT bio-succinic acid or 520 MT bioethanol could be produced annually using the carbohydrate fraction. In the fourth case study, it was estimated that 1040 MT biodiesel or 528 MT biocrude could be produced annually using the lipid fraction. Producing renewable commodity fuels and chemicals using the algal biomass generated in a WRRF will help to displace fossil fuel-derived products, generate new jobs, and benefit the environment.
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    Potential of using microalgae to sequester carbon dioxide and processing to bioproducts
    (Royal Society of Chemistry, 2023-09-15) Balan, Venkatesh; Pierson, James; Husain, Hasan; Kumar, Sandeep; Saffron, Christopher; Kumar, Vinod
    Algae are microscopic photosynthetic prokaryotic or eukaryotic organisms that can naturally grow in fresh or marine water in the presence of sunlight. Algae are capable of sequestering CO2 and utilize nutrients like nitrates, phosphates, and other micronutrients in water to increase their body mass. In the past few decades, algal biomass has been investigated by the scientific community because of its promising applications in producing renewable food, feed, fuels, and chemicals. Additionally, microalgae's ability to fix large amounts of greenhouse gas (GHG) such as carbon dioxide (CO2) has led researchers to investigate microalgae as an alternative way of combating climate change by sequestering flue gas containing CO2 emitted from industries such as coal power plants, cement, steel, and petroleum refineries. This review outlines different sources of CO2 emissions and capturing technology including microalgae. Details about the methods of cultivating and separating the algal biomass followed by thermochemical and biochemical conversion to fuels/chemicals, microalgae-derived bioplastics, and microalgae biomass blended plastic are outlined in this review. Commercially viable continuous and semi-continuous biorefining processes such as hydrothermal flash hydrolysis and environmental benefits of using microalgae as carbon sinks and wastewater treatment are also provided.