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A new porous carbon structures made by sintering whey powder in a mold at 150ºC and subsequent carbonization and/or activation are described. These porous carbon structures represent a step beyond simple activated carbon monoliths, as they can take the shape of any mold and machined if necessary. These carbon materials have a porosity that can reach up 70%, made up of a system of hierarchical and interconnected pores, which gives them a high permeability. Furthermore, they have a much higher mechanical strength than other porous carbon monoliths., The authors are grateful for the support of the Principado de Asturias-FICYT-FEDER (Project PCTI-Asturias IDI/2018/000118) and MINECO (Project CTQ2017-87820-R).

The synthesis of resorcinol–formaldehyde (RF) xerogels is versatile enough to provide materials with custom pore size distributions in the meso-/macroporous range. Specifically, seven xerogels were synthesised by changing the pH of the same RF solution, from pH 3 to pH 6. The resulting materials presented meso-/macroporous size distributions with average pore sizes from, The authors gratefully acknowledge the financial support received from the Consejo Superior de Investigaciones Científicas (Project I-LINK1200), Ministerio de Economía, Industria y Competitividad (Project CTQ2017-87820-R) and Principado de Asturias– FICYT-FEDER (Project PCTI-Asturias IDI/2018/000118).

Extensive studies on the correlation between synthesis variables and the final properties of resorcinol-formaldehyde carbon gels have been performed. This knowledge allows us to obtain carbon gels with analogous mean pore sizes and porosity from different combinations of synthesis variables. However, although the materials exhibit these similar characteristics, their behaviors may be very different in certain applications. Since the distribution and connectivity of the polymeric clusters are strongly affected by variables such as the amount of water and methanol in the precursor solution, it seems that the pore tortuosity and thus the permeability of the materials are also dependent on these factors. Further analysis of a series of carbon gels with the apparent same porosity shows how an increase in the amount of water or a suitable combination of methanol content and the pH of the precursor solution used for the polymerization process generate less tortuous pore structures. This allows us to attain even finer tuning of the porous structure of RF carbon gels either to reduce pressure drop or to increase the residence time of solutes in separation processes., Authors are grateful for the financial support received from the Ministerio de Economia, Industria y Competitividad from Spain (CTQ2017-87820-R) and Principado de Asturias–FICYT-FEDER(IDI/2018/000118). SFL is grateful to the Administración del Principado de Asturias for her research training grant awarded through the “Severo Ochoa” program. LARM thanks CONACYT, Mexico for a post-doctoral grant (CVU No 330625, 2017).

Carbon-based materials have been shown to enhance anaerobic digestion processes by promoting direct interspecies electron transfer in methanogenic consortia. However, little is known on their effects during the treatment of complex substrates, such as those derived from protein-rich wastewaters. Here, organic xerogels (OX) are tested, for the first time, as accelerators of the methanogenic activity of an anaerobic consortium treating a synthetic protein-rich wastewater. Three OX with distinct pore size distribution (10 and 1000 nm for OX-10 and OX-1000, respectively) and structural conformation (graphene oxide integration into OX-10-GO polymeric matrix) were synthesized. OX-1000 promoted the highest methane production rate (5.21 mL/g*h, 13.5% increase with respect to the control incubated without OX) among the synthesized OX. Additionally, batch bioreactors amended with OX achieved higher chemical oxygen demand (COD) removal (up to 88%) as compared to the control, which only showed 50% of COD removal. Interestingly, amendment of bioreactors with OX also triggered the production of medium-chain fatty acids, including caprylate and caproate. Moreover, OX decreased the accumulation of ammonium, derived from proteins hydrolysis, partly explained by their adsorption capacities, and probably involving their electron-accepting capacity promoting anaerobic ammonium oxidation. This is the first time that OX were successfully applied as methanogenic accelerators for the anaerobic treatment of synthetic protein-rich wastewater, increasing the methane production rate and COD removal as well as triggering the production of medium chain fatty acids and attenuating the accumulation of ammonium. Therefore, OX are proposed as suitable materials to boost the efficiency of anaerobic systems to treat complex industrial wastewaters., Universidad Nacional Autónoma de México (UNAM, PAPIIT grant TA100120 and UNAM, DGAPA Grant Number COIC/DDTPA/064/2020).