Browsing by Author "Cabrera, Daniela V."

Now showing 1 - 5 of 5
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    Design of a High-Rate Wastewater Treatment Process for Energy and Water Recovery at Biorefineries
    (2023) Li, Yalin; Kontos, George A.; Cabrera, Daniela V.; Avila, Nickolas M.; Parkinson, Thomas W.; Viswanathan, Mothi Bharath; Singh, Vijay; Altpeter, Fredy; Labatut, Rodrigo A.; Guest, Jeremy S.
    Industrial wastewaters rich in organic carbon have potential for value generation, but conventional, low-rate, anaerobic-aerobic wastewater treatment (WWT) processes often incur significant capital expenses and energy consumption. In this study, we leveraged experimental data for biorefinery-derived wastewaters to characterize the implications of transitioning from a conventional, low-rate process to a high-rate, multistage anaerobic process. We designed and simulated these WWT processes across seven first-and second-generation (1G/2G) biorefineries and evaluated the implications for biorefinery sustainability through techno-economic analysis (TEA) and life cycle assessment (LCA). Compared to the conventional design, the new process can substantially reduce capital costs and electricity usage. These improvements were particularly evident for 2G biorefineries, translating to 5%-13% lower minimum product selling prices (MPSPs) and 7%-135% lower 100-year global warming potentials (GWPs; the 135% reduction is due to the transition of one biorefinery from net emission [0.87 kg of CO2e center dot gal-1] to net sequestration [-0.31 kg of CO2e center dot gal-1]). Biorefineries could further reduce the MPSP through the renewable identification number (RIN) credits by upgrading and selling the biogas as renewable natural gas, but at the expense of increasing GWP. When normalized, the COD management cost ranged from $-56 to $465 per tonne of COD, indicating that wastewater could be a net source of revenue for some biorefineries.
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    Enhancing energy recovery of wastewater treatment plants through hydrothermal liquefaction
    (2023) Cabrera, Daniela V.; Barria, David A.; Camu, Esteban; Celis, Crispin; Tester, Jefferson W.; Labatut, Rodrigo A.
    Sewage sludge (SS) management constitutes both a challenge and an opportunity for the sustainability of wastewater treatment plants (WWTPs). Standalone anaerobic digestion (AD) stabilizes the biodegradable organics contained in SS but recovers only a fraction of the chemical energy stored therein and produces large amounts of un-stabilized sludge. Hydrothermal liquefaction (HTL) coupled with AD can enhance the treatment and energy recovery of SS. Standalone AD was compared against (1) an HTL-AD configuration, with SS as HTL input, and the generated aqueous product (AP) as AD input; and (2), an AD-HTL-AD configuration, with SS as AD input, the digestate as HTL input, and the generated AP as AD input. Both configurations decreased the SS' COD from 27.5 to 0.6 g L-1, while the overall energy recovered was increased up to 2.2-fold relative to conventional SS treatment using only AD. Under the HTL-AD configuration, biocrude yields were higher (i.e., 26.4 vs. 15.8) and the AP generated was more biodegradable (0.78 vs. 0.65), than those obtained under the AD-HTL-AD configuration. Monte Carlo uncertainty analyses confirmed that overall energy recoveries would follow the order AD-HTL-AD > HTL-AD > AD; with energy recoveries (95% confidence) between, 63.5-94.7%, 54.6-91.2%, and 33.2-71.1%, respectively. This study shows that, by implementing HTL as a standalone SS treatment, WWTPs can recover more energy than using AD alone. Furthermore, WWTPs with existing AD would recover additional energy through HTL of the generated digestate, significantly reducing the environmental impacts and costs of conventional solids management.
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    Kinetic and Thermodynamic Evidence of the Paal-Knorr and Debus-Radziszewski Reactions Underlying Formation of Pyrroles and Imidazoles in Hydrothermal Liquefaction of Glucose-Glycine Mixtures
    (2024) Sudibyo, Hanifrahmawan; Budhijanto, Budhijanto; Cabrera, Daniela V.; Mahannada, Aqiela; Marbelia, Lisendra; Prasetyo, Dwi Joko; Anwar, Muslih
    We evaluated Paal-Knorr and Debus-Radziszewski reactions as the mechanisms underlying formation of pyrroles and imidazoles, respectively, in hydrothermal liquefaction (HTL) via semicontinuous HTL experiments on a glucose-glycine mixture. We developed cheminformatic-based HTL reaction pathways for a range of feedstock pH (2-12), reaction temperatures (280-370 degrees C), and reaction times (2-60 min). The developed pathways were validated using transient concentration of the reacting compounds and assessed using reversible power-law kinetics, Arrhenius equation, and Maxwell relation for Gibbs free energy. The assessment informed the exothermicity of both proposed mechanisms and their activation under acidic conditions with (1) succinaldehyde and amino acid/ammonia and (2) alpha-dicarbonyls, formaldehyde, and amino acid/ammonia as precursors, respectively. Endothermic amidation and exothermic decarboxylation followed both reactions, producing amide- and alkyl-substituted pyrroles and imidazoles in biocrude and an aqueous-phase coproduct. Moreover, exothermic C-C coupling of pyrroles and a series of exothermic Wittig olefination and Hoesch reactions involving dicarboxylic acid of imidazole, fumaronitrile, and ylide precipitated polypyrrole and azepine- and azocine-embedded imidazole in hydrochar. Meanwhile, the HTL of neutral and alkaline feedstocks presented a transition from alkali-catalyzed (e.g., the endothermic Maillard reaction between pyruvaldehyde and amino acid/ammonia producing pyrazines and oxazoles) to acid-catalyzed (e.g., the Debus-Radziszewski reaction) mechanisms at reaction times longer than 10 min due to significant acetic acid formation from the decomposition of carbohydrate and protein monomers. This study proved that the HTL mechanism of formation of N-heterocycles varied with feedstock pH.
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    Reactivity and Stability of Natural Clay Minerals with Various Phyllosilicate Structures as Catalysts for Hydrothermal Liquefaction of Wet Biomass Waste
    (2023) Sudibyo, Hanifrahmawan; Cabrera, Daniela V.; Widyaparaga, Adhika; Budhijanto, Budhijanto; Celis, Crispin; Labatut, Rodrigo
    We evaluated natural clay minerals representing all classesofphyllosilicates as in situ catalysts for hydrothermal liquefaction(HTL) of anaerobically digested cattle manure at 350 & DEG;C for 1h, i.e., kaolinite, montmorillonite, talc, vermiculite, phlogopite,meixnerite, attapulgite, and alumina. The relative compositions ofstrong Bronsted (SBrA), strong Lewis (SLA), and weak Lewis acidic(WLA) sites and the strong (SBS) and weak (WBS) basic sites of clayminerals significantly affected the formation of HTL products (i.e.,biocrude oil, hydrochar, and aqueous- and gas-phase coproducts) andthe distribution and speciation of elements. The general mechanisticroles of these active sites are as follows: (1) SBrA catalyzed thebiocrude-forming reactions and inhibited the hydrochar-repolymerizingreactions; (2) SLA promoted the production of hydrochar precursors;(3) WLA enhanced the hydrodeoxygenation, hydrodenitrogenation, andhydrodesulfurization of biocrude by utilizing the hydrogen generationcatalyzed by WBS; and (4) SBS increased the production of organicacids solubilizing nutrients into the aqueous-phase coproduct (HTL-AP).Montmorillonite was the most suitable for the HTL catalyst due tothe optimal composition of these active sites, leading to achievingmaximal biocrude energy recovery (i.e., 82%) with low heteroatomscontent (i.e., 15% O, 0.24% N, and 0.08% S), minimal hydrochar yield(i.e., 10%), and maximal nutrient yield in HTL-AP, i.e., 71% P, 54%Mg, 29% NH3-N, and 14% Ca. In addition, the crystallinestructure of montmorillonite remained intact after the HTL process.This study informs comprehensive catalytic roles of different surface-activesites of clay minerals useful for future development of clay-basedcatalysts for more sustainable overall HTL systems.
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    Syngas production from phenolic pollutants via a series of hydroxylation, ring cleavage, and aqueous-phase reforming catalyzed by a hydrotalcite-supported Fe-Mn-Ni alloy
    (2024) Sudibyo, Hanifrahmawan; Cabrera, Daniela V.; Labatut, Rodrigo; Supriyanto, Calvin J.; Budhijanto, Budhijanto; Widyaparaga, Adhika
    A trifunctional catalyst facilitating a series of hydroxylation, oxidative ring opening, and aqueous-phase reforming reactions was developed to convert phenolic wastewater into syngas. The definitive screening design experiment at 250 degrees C for 5 h with 1.75% H(2)O(2 )and 2 wt% catalyst loading demonstrated the importance of Fe, Mn, and Ni among the first-row transition metals to be impregnated into hydrotalcite to acquire the trifunctional feature. The surface chemistry characterization revealed that they improved the amount of strong and weak Br & oslash;nsted (SBrA and WBrA) and Lewis (SLA and WLA) acidic active sites. The mechanistic roles of these sites via semi-continuous kinetic investigation at 200-300 degrees C for 1-5 h with 1.75% H2O2 and 2 wt% catalyst loading were unraveled: (1) SBrA (surface metal oxyhydroxides) facilitated hydroxylation and homolytic cleavage producing hydroxyphenols; (2) WBrA (surface metal hydroxides) promoted ring opening of hydroxyphenols yielding oxo- and di-carboxylic acids; (3) WLA (mineral phase with a tetrahedral coordination) catalyzed reforming of acids into syngas; and (4) SLA (mineral phase with an octahedral coordination) improved the H2 yield by promoting the water-gas shift reaction. The optimal content of Fe, Mn, and Ni was 49.4, 21.2, and 29.4 wt%, respectively, from 20 wt% of active metals on the support to achieve the maximal organic carbon removal (similar to 82%) and H2 yield (similar to 80%) with a CO-to-H2 ratio of 0.6, useful for chemical building block synthesis. The optimized catalyst demonstrated high activity and reusability, with a turnover number and frequency of similar to 1 x 106 and similar to 6 x 104 s-1, respectively, marking a breakthrough in sustainable syngas production.