Examinando por Autor "Puyol, D."

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Chemically activated hydrochars as catalysts for the treatment of HTC liquor by catalytic wet air oxidation
(Elsevier, 2023) Mora, A. de; Diaz de Tuesta, J.L.; Pariente, M.I.; Segura, Y.; Puyol, D.; Castillo, E.; Lissitsyna, K.; Melero, J.A.; Martínez, F.
Hydrothermal carbonization (HTC) is a highly efficient and valuable technology for treating wet solid wastes and producing solid carbon-based materials named hydrochar. In this work, a hydrochar coming from the HTC of an anaerobic digestion sludge of wastewater treatment plant was used to assess the influence of several activation agents, a base (KOH) and different chloride salts (FeCl3, ZnCl2, and CuCl2) with the exact molar quantities, to develop materials with enhanced surface area and potential inclusion of metal active species for application in wet air oxidation processes. The KOH as an activating agent increased the surface area of hydrochar up to ca. 1000 m2/g of BET surface area. The employment of CuCl2 and FeCl3 as activating agents allows Cu- and Fe-rich doped materials of remarkable surface areas with 49.1 and 42.5 wt% of each metal, respectively. Likewise, the catalytic behavior of the different synthesized carbon-based materials as metal-free and metal-doped catalysts was evaluated for the Catalytic Wet Air Oxidation (CWAO) of a HTC aqueous liquor from a HTC process of animal manure to produce a valuable stream of higher biochemical methane potential in anaerobic digestion. CWAO effluents increased the proportion of carboxylic acids as final by-products due to the oxidation of more complex organic compounds of the initial effluent (ketones, phenols, aromatics and olefins). The CWAO treatments improve the anaerobic digestion rate in biochemical methane potential tests, although the methane production was limited by the lower TOC concentration of the treated streams after CWAO. This research contributes to developing sustainable and efficient strategies for the HTC-liquor treatment, using its solid hydrochar as catalysts, closing the loop of a Circular Economy.
Improvement of biogas production and nitrogen recovery in anaerobic digestion of purple phototrophic bacteria by thermal hydrolysis
(Elsevier, 2022) Segura, Yolanda; Molina, Raúl; Rodríguez, I.; Hülsen, T.; Batstone, D.; Monsalvo, V.; Martínez, F.; Melero, José Antonio; Puyol, D.
Purple phototrophic bacteria (PPB) are a novel driver to recover organics and nutrients from wastewater by assimilative growth. Depending on the source, assimilated resources from the PPB biomass can still be recovered after a releasing step. Anaerobic digestion (AD) releases carbon and nutrients, but the release is incomplete. Thermal hydrolysis (TH) as a pretreatment before AD improves the digestibility, release, and subsequent recovery potentials. This work determines the effects of TH in batch and continuous modes regarding methane potential, nutrients’ release efficiencies, volatile solids destruction, degradability, and hydrolysis rates. Continuous runs over 165 days (d) confirmed enhanced recovery potentials, achieving up to 380 LCH4/kgVS (83 % solids destruction) and 73 % N release, respectively. The TH pretreatment is energy-intensive, but with appropriate heat recovery and increased methane production in the AD of the pretreated biomass, a combined configuration is energy positive.
The synergy of catalysis and biotechnology as a tool to modulate the composition of biopolymers (polyhydroxyalkanoates) with lignocellulosic wastes
(Elsevier, 2021) Ventura, M.; Puyol, D.; Melero, J.A.
An integrated method coupling of heterogeneous and biological catalysis has proven effective for producing biopolymers using lignocellulosic urban solid waste as feedstock. Catalysts based on cheap and earth-abundant metals, such as Fe, Mg, Ca, or Zr with basic or acid properties, were used in the pre-treatment step, and phototrophic mixed cultures were chosen for the biological step. By changing catalysts composition, reaction temperature, and catalysts loading, high performance of the catalysts was achieved under the more optimal pre-treatment of lignocellulose waste, with a solid conversion up to 86%, enriching the solid phase in the lignin polymer. The biological conversion of the liquid effluent in a photobioreactor yielded high production of PHA (up to 36 wt% on a dry basis). The characteristics of the polymer were strongly dependent on liquid feed, the composition of which depended on the type of catalysts used in the previous step. A poof of the concept of a new biorefinery design has been presented in this work, showing that it is possible to enhance the advantages of two different disciplines, heterogeneous catalysis, and photoheterotrophic biotechnology.