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11 Páginas.-- 6 Figuras.-- 1 Tabla, Copolymers based on vegetable oils and sulfur have recently been developed using the inverse vulcanization technique for water remediation. This study aimed to create a copolymer with heteroatoms, such as nitrogen, to improve adsorption efficiency and examine the competition and synergy between heavy metals in the adsorption process. FTIR, 1H NMR, solid 13C NMR, zeta potential, nitrogen adsorption, Elemental analysis, TEM, and SEM were used to characterize the copolymers synthesized. Once metal adsorption was optimized using the synthesized copolymers, a comparative adsorption study was conducted for the removal of individual heavy metals, Cd2+, Pb2+, Zn2+, Mn2+, and Cu2+ (100 mg/L), using two copolymers, S/CO:80/20 and S/CO/TAA:80/14/6. The copolymers exhibited a higher affinity for soft metals, such as Cd2+, Pb2+, and Cu2+, when they are individually and in a mixture. After 1 h, the S/CO:80/20 copolymer removed 47%, 40%, and 13% of these metals. While with the S/CO/TAA:80/14/6 copolymer removal increased to 10%, 24%, and 53%, respectively respect to S/CO:80/20 copolymer. The introduction of heteroatoms in the copolymers improved their removal efficiency, particularly for heavy metals like Pb2+. Overall, this study demonstrates a promising approach for sustainable water remediation using copolymers., The authors are grateful to the Regional Government of Andalusia, Junta de Andalucía, Consejería de Economía y Conocimiento (Project UHU-1257728).

10 Páginas.-- 4 Figuras.-- 4 Tablas, According to recent studies, the anaerobic digestion of strawberry extrudate is a promising option with potential in the berry industry biorefinery. However, the lack and/or unbalance of concentrations of metals in some agro-industrial residues could hamper methane production during the anaerobic digestion of these kinds of wastes. In this study, a fractional factorial design was applied to screen the supplementation requirements regarding six metals (Co, Ni, Fe, Cu, Mn, and Zn) for methane production from strawberry extrudate (SE). The logistic model was used to fit the experimental data of methane production-time. It allowed identifying two different stages in the anaerobic process and obtaining the kinetic parameters for each step. Maximum methane production obtained in the first (Bmax) kinetic stage, the methane production in the second stage (P), and the maximum methane production rates (Rmax) concluded a statistically significant effect for Ni and Zn. The second set of experiments was carried out with Ni and Zn through a central composite design to study the concentration effect in the anaerobic digestion process of the strawberry extrudate. The parameters P and Rmax demonstrated a positive interaction between Ni and Zn. Although, Bmax did not prove a statistically significant effect between Ni and Zn., This research was funded by the Spanish Ministry of Economy, Industry, and Competitiveness through the Research Project CTM 2017-83870-R.

9 Páginas.-- 5 Figuras.-- 2 Tablas, In recent years, there has been an increasing concern related to the contamination of aqueous ecosystems by heavy metals, highlighting the need to improve the current techniques for remediation. This work intends to address the problem of removing heavy metals from waterbodies by combining two complementary methodologies: adsorption to a copolymer synthesized by inverse vulcanization of sulfur and vegetable oils and phytoremediation by the microalga Chlorella sorokiniana to enhance the metal adsorption. After studying the tolerance and growth of Chlorella sorokiniana in the presence of the copolymer, the adsorption of highly concentrated Cd2+ (50 mg L-1) by the copolymer and microalgae on their own and the combined immobilized system (AlgaPol) was compared. Additionally, adsorption studies have been performed on mixtures of the heavy metals Cd2+ and Cu2+ at a concentration of 8 mg L-1 each. AlgaPol biofilm is able to remove these metals from the growth medium by more than 90%. The excellent metal adsorption capacity of this biofilm can be kinetically described by a pseudo-second-order model., The authors are grateful to the Regional Government of Andalusia, Junta de Andalucía, Consejería de Economía y Conocimiento, University of Huelva (P.O. Feder UHU-1257728) and Atlantic Copper Foundation (Cátedra Atlantic Copper Universidad de Huelva). A.L-V wants to thank also Next Generation European Funds and the Ministry of Universities of Spain for funding the Recualificación del Profesorado Universitario system. The authors acknowledge further support by the Swedish Research Council FORMAS (2019-00492 to C.F.), the NordForsk NCoE program “NordAqua” (Project no. 82845 to C.F.) and Umeå University (to A.L-V. and C.F.).

12 Páginas.-- 2 Figuras.-- 4 Tablas, This research evaluates the anaerobic digestion (AD) process of the residue generated in a new olive-oil manufacturing process for cold-pressed olive, a residue consisting of a mixture of the wastewater and solid waste obtained from this process. Additionally, in order to assess the possible influence of the level of ripening of the olives on the performance of anaerobic processing, olives of the Picual variety were collected at two stages, i.e., green olives and olives in veraison. The AD processes of the residues obtained from the cold-pressing process and the process without pressure (control) were comparatively assessed by means of biochemical methane potential (BMP) assays conducted at mesophilic temperature (35 ± 1 °C). Maximum values for methane yield (390 ± 1 NL CH4/kg VSadded) and biodegradability (84.5%) were obtained from the cold-pressed green olive residues. For the rest of the wastes studied, biodegradability also reached high values, ranging from 79.1 to 79.6%. The logistic model adequately fit the experimental data and allowed for the assessment of the anaerobic biodegradation of these wastes and for obtaining the kinetic parameters for each case studied. The theoretical values for ultimate methane production predicted from this model showed less than a 1% deviation from the experimental values. A decrease was detected for both types of olives tested in the rate of maximum methane production, Rm, during the cold-pressing process, from 44.3 ± 0.1 to 30.1 ± 1.3 L CH4/(kg VS·d) (green olives) and from 43.9 ± 1.5 to 38.7 ± 1.6 L CH4/(kg VS·d) (olives in veraison). Finally, the highest energy output result was detected in the waste from cold-pressed green olives (15.7 kJ/g VSremoved), which coincided with its high methane yield., This research was funded by the regional government of Andalucía, Junta de Andalucía, Project 18-616, “Consejería de Economía, Conocimiento, Empresas y Universidad”, Andalucía, Spain, and Project PID2020-114975RB-100/AEI/10.13039/501100011033 was financed by the Spanish Ministry of Science and Innovation. The project FEDER UPO-380782 was financed by the regional government of Andalucía, Junta de Andalucía, “Consejería de Trasformación Económica e Industria”, providing financial support to Dr. Fernández-Rodríguez.

10 Páginas.-- 2 Figuras.-- 3 Tablas, The feedstock seasonality has been poorly studied in the anaerobic digestion process. The seasonality could disturb the digestion process stability, mainly for fruit and vegetable waste. In this study, three seasonal waste mixtures generated in wholesale markets were reduced to 10, 6, and 4 mm to assess the influence of seasonality and particle size reduction on anaerobic biodegradability. The methane yield ranged between 298 and 465 mL CH4 g VS−1 (volatile solids). Waste mixtures produced in spring at 10-mm particle size presented higher methane production than in autumn/winter and summer, i.e., 32% and 61%, respectively. Methane production decreased with reducing particle size for waste produced in spring from 482 ± 12 to 310 ± 1 mL CH4 g VS−1. In contrast, waste produced in autumn/winter and summer did not show high differences among different sizes. Despite these differences, mixtures with the smallest particle size presented the highest methane production rate. Graphical abstract: [Figure not available: see fulltext.], Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was funded by the project entitled “Employing circular economy approach for OFMSW management within the Mediterranean countries – CEOMED” number A_B.4.2_0058, funded under the ENI CBC MED 2014–2020 programme.

9 Páginas.-- 3 Figuras.-- 1 Tabla, Microalgae are being proposed as excellent substrates for different biorefinery processes. Anaerobic digestion process of microalgae is one of these interesting processes but has some limitations in deleting cell walls. For this reason, many studies proposed different types of pre-treatments, entailing energy, operation, and investment costs. This work aims to optimize the anaerobic digestion of the microalgae Chlorella sorokiniana and Chlorella sorokiniana (strain S12/S13/S16) without any pre-treatment by selecting the optimal harvesting time. The greatest influence is seen at 5:00 PM in methane production for both microalgae. For Chlorella sorokiniana, it is the most optimal moment for anaerobic digestion, whereas Chlorella sorokiniana (strain S12/S13/S16) is the least optimal. In the other harvesting times, both microalgae present a similar methane production, i.e. 173 ± 12 mL CH4/g of total volatile solids. The highest methane production rate values were obtained during peak sunlight, 1:00 PM and 8:00 AM, respectively, and lower overnight., The author(s) reported there is no funding associated with the work featured in this article.

9 Páginas.-- 2 Figuras.-- 4 Tablas, The aim of the present research was to investigate the influence of the application of a novel cold-pressing system in olive oil manufacturing on the characteristics of olive pomace (OP) and on its valorization by anaerobic digestion (AD). Green olives and olives in veraison, both from the Picual variety, were used with the objective of assessing the effect of ripening level on the performance of the AD processes. The AD processes of these OPs were assessed in biochemical methane potential (BMP) tests. The maximum methane yield (327 ± 5 mL CH4/g VS) and biodegradability value (90.8%) were found for the OP derived from green olives without cold-pressing, which showed the highest soluble COD (113 g O2/L) and the lowest total phenolic concentration (9 g gallic acid/L). The first-order and Transference Function (TF) kinetic models were employed to evaluate the variation in methane production with time and to obtain the kinetic parameters of the anaerobic processes of the four OPs tested. The kinetic constant from the first-order model, k, did not show significant differences for the four OPs tested and ranged between 0.23 and 0.27 day−1. The TF revealed that the values for the maximum methane production rate (Rmax) were slightly higher for the OPs derived from green olives compared to those obtained from olives in veraison. For the green olives, the cold-pressing system caused a decrease in the value of Rmax from 87 ± 7 to 73 ± 6 mL CH4/(g VS·d)., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This study was funded by Project PY18-616 funded by the regional government of Andalucía, Junta de Andalucía, Consejería de Economía, Conocimiento, Empresas y Universidad, Andalucía, Spain, and Project PID2020-114975RB-100/AEI/10.13039/501100011033 financed by the Spanish Ministry of Science and Innovation. The project FEDER UPO-380782 financed by the regional government of Andalucía, Junta de Andalucía, Consejería de Trasformación Económica, Industria, Conocimiento providing financial support to Dr. Fernández-Rodríguez.

9 Páginas.-- 5 Figuras.-- 3 Tablas, Mechanical treatments can be simple and feasible methods for enhancing the anaerobic digestion of lignocellulosic substrates. This work aims to relate the direct effect of five different mechanical treatments, i.e., variation in the size and number of particles, with the variations in the chemical composition and, subsequently, the effect over the anaerobic digestion of residual raspberry extrudate, which was used as a model substrate. A high variation in the number of particles and the particle size distribution was achieved depending on the mechanical treatment applied, reaching the highest number of particles for the treatments with knife mills and mortar (around 8000 particles per gram). The higher number of particles was related to higher solubilisation, including phenolic compounds and sugars. The combination of knife mills and mortar pretreatment, which presented the highest number of particles, resulted in a 66% more of polyphenols in comparison to the raw substrate. However, the presence of anthocyanins was higher in mechanical treatments with less effect. The enhancement of the anaerobic digestion was clearly related to the increment in the number of particles of small size after the mechanical treatments. The highest methane yield coefficient (236 ± 11 mL CH4/g volatile solids) was achieved for the raspberry extrudate treated with knife mills., This research was funded by the Spanish Ministry of Economy, Industry, and Competitiveness for funding this research through Project CTM2017-83870-R. Antonio Serrano is grateful to the Spanish Ministry of Science, Innovation, and Universities for his Juan de la Cierva-Incorporacion fellowship (IJC2019-040933-I). Finally, Erika Sinisgalli wants to acknowledge the Erasmus Plus Programme of the EU for the fellowship received for her traineeship at the Instituto de la Grasa (CSIC), Seville, Spain.

14 Páginas.-- 5 Figuras.-- 2 Tablas, The accumulation of volatile fatty acids (VFAs) through the anaerobic fermentation of organic waste, such as strawberry extrudate, is proposed for this work. A hydrothermal treatment was carried out, and it was proposed to break the complex matrix of the strawberry extrudate to favour the hydrolysis stage of the anaerobic digestion process. The production of volatile fatty acids from treated and untreated strawberry was evaluated by adjusting the pH to 5 and 9. After the hydrothermal treatment of the strawberry extrudate, an increase in the solubilisation of organic matter, such as sugars and phenols, was observed. In the production of VFAs by means of anaerobic digestion of the pretreated strawberry extrudate, a significant increase in the accumulation of volatile fatty acids was demonstrated at a pH of 9 with respect to the untreated strawberry extrudate. In addition, the operational pH also had a strong effect on the individual VFA profile. A stream enriched in acetic acid was obtained at a pH of 9 (around 65% of the VFAs), whereas the operation at a pH of 5 resulted in a more complex composition with a high percentage of propionic acid (29% of the VFAs)., The authors are also very grateful to the Spanish Ministry of Science and Innovation for funding this research through the project PID2020-116698RB-I00.

9 Páginas.-- 4 Tablas.--5 Figuras, Inverse vulcanization has emerged as a reaction to achieve hybrid inorganic-organic polymeric materials, which allows us to use the high amount of sulfur produced during refining crude oil as a raw material. In this study, a gamut of copolymers has been formulated using a quantitative atom economy, that is, elemental sulfur and castor oil (CO), as can be seen from the appearance of gels to crystalline copolymers. The physical and chemical characterization has been carried out using techniques such as Fourier transform infrared spectroscopy, NMR, differential scanning calorimetry, and thermogravimetric analysis. Furthermore, two types of copolymers have been selected to test their capabilities in different applications. Copolymers with S ratios higher than 30% have been tested for water remediation, with high removal rates for metals such as lead and cadmium. Although copolymers with a percentage of up to 10% sulfur have been tested as bio-based lubricants, showing improvements in terms of viscosities compared to the initial vegetable oil., The authors thank financial support from Junta de Andalucía, Consejería de Economía y Conocimiento, and University of Huelva (P.O. Feder UHU-1257728).

The authors are very grateful to the Spanish Ministry of Science and Innovation for funding this research through the project PID2020-116698RB-100. Antonio Serrano is grateful to the Spanish Ministry of Science, Innovation, and Universities for his Juan de la Cierva-Incorporacion fellowship (IJC2019-040933-I) and to the Economic Transformation, Industry, Knowledge and Universities Department of the Andalucia Autonomous Government for his Emergia fellowship (EMERGIA20_00114). The authors are grateful to the Regional Government of Andalusia, Junta de Andalucia, Consejeria de Economia y Conocimiento (Project UHU-1257728), for providing additional financial support. Funding for open access charge: Universidad de Granada/CBUA. The authors also wish to express their gratitude to Javier Ramiro-Garcia and Ainoa Botana Samper for their assistance with this research., Strawberry extrudate (SE) is a by-product derived from the elaboration of strawberrytasted products. Adequate management of this substrate would entail a new source of benefit for the berry sector, instead of a costly waste to be treated. The aim of this work is to assess the potential use of SE as a carbon soured for volatile fatty acids (VFA) production through anaerobic fermentation at controlled pH (5, and 9) and without pH control (operational pH around 7). Anaerobic digestion at pH 7 resulted in a negligible accumulation of VFA, being mainly degraded to methane. The operation at the other pHs resulted in a marked drop in methane production and, thus, the accumulation of VFA. At pH 9, around 50% of the fed CODtot (total chemical oxygen demand) was accumulated as VFA. Acetic acid represented 61% of these total VFA. The operation at pH 5 resulted in a lower VFA accumulation, i.e. 15% fed CODtot, although the VFA profile was more complex than at pH 9. Propionic and butyric acids represented 43% and 32%, respectively, of the total VFA accumulated at pH 5., Spanish Government PID2020-116698RB-100 IJC2019-040933-I, Economic Transformation, Industry, Knowledge and Universities Department of the Andalucia Autonomous Government EMERGIA20_00114, Regional Government of Andalusia, Junta de Andalucia, Consejeria de Economia y Conocimiento UHU-1257728 Universidad de Granada/CBUA

The production of strawberry concentrate produces a side stream after extrusion that is commonly landfilled. This strawberry extrudate (SE), of lignocellulosic character, contains valuable bioactive compounds such as sugars and phenols. Thermal treatments, such as steam explosion, are currently used for the valorisation of agricultural lignocellulosic wastes due to their ability to impact the structure of the lignocellulose and hemicellulose present in these wastes, favouring the disruption of fibrous material. Steam explosion has already been shown as a promising technology for phenol recovery from SE. Biogas is an additional valuable resource that might be produced from thermally pretreated and de-phenolised SE. This study assessed the influence of a steam-explosion pretreatment and the subsequent recovery of phenolic compounds from the long-term operation of a semi-continuous anaerobic digester of pretreated SE. The anaerobic digestion of SE steam exploded at 220 &deg, C for 5 min and de-phenolised was stable at an OLR of 0.5 g of volatile solids (VS)/(L&middot, d), which permitted a specific production rate of 135 &plusmn, 11 mL of CH4/(g of VS&middot, d). The system was not able to operate at an OLR of 1 g of VS/(L&middot, d), which resulted in a failure of the process. Despite the inhibition threshold of phenolic compounds not being achieved, the inhibition of the anaerobic digestion process at an OLR of 1 g of VS/(L&middot, d) was most likely due to the overloading of the system. This was indicated by the accumulation of soluble organic matter and volatile fatty acids. The increase in the propionic acid concentration up to 1300 mg/L when operating at OLRs higher than 0.5 g of VS/(L&middot, d) could be the main factor responsible for the inhibition. An economic evaluation showed that the proposed approach (steam explosion, phenol recovery, and anaerobic digestion) would offer positive benefits, taking into account the high phenolic recovery (0.90 g of gallic acid equivalents/kg of extrudate) and the low sales price of the phenol extract, i.e., EUR 0.610/g of gallic acid equivalents, needed to reach zero net profit.

Raspberry extrudate residue has bioactive compounds in its matrix that are considered high-added value compounds. In the present study, different hydrothermal treatments were carried out using different operational systems, temperatures and times to solubilize raspberry extrudate in order to obtain these bioactive compounds (i.e., sugars and phenolic compounds). Hydrothermal treatment conditions were assessed in the range of 60 &deg, C to 210 &deg, C, with increments of 30 &deg, C. The hydrothermal treatment at 210 &deg, C for 5 min with direct steam and decompression was the most efficient process based on the solubilization of sugars and phenols, as well as on the antioxidant capacity of the products recovered in the liquid phase after treatment. Under these conditions, the concentration of soluble phenols was more than double the concentration in the raw raspberry extrudate, with more than 5000 mg phenols per kilogram of raspberry extrudate. The obtained values demonstrate the potential of applying this treatment for recovering valuable bioactive compounds from raspberry extrudate.

This study was on the comparison of hydrothermal treatments at 170 &deg, C (steam injection) and 220 &deg, C (steam explosion) to solubilize the organic matter contained in residual strawberry extrudate, focusing on phenolic compounds that were susceptible to be extracted and on sugars. After the extraction step, the remaining strawberry extrudate phases were subjected to anaerobic digestion to generate biogas that would compensate the energy requirements of the suggested hydrothermal treatments and to stabilize the remaining waste. Hydrothermal treatment at 220 &deg, C allowed the recovery of 2053 mg of gallic acid eq. per kg of residual strawberry extrudate. By contrast, after hydrothermal treatment at 170 &deg, C, only 394 mg of gallic acid eq. per kg of residual strawberry extrudate was recovered. Anaerobic digestion processes were applied to the de-phenolized liquid phase and the solid phase together, which generated similar methane productions, i.e., around 430 mL CH4/g volatile solids, after both 170 &deg, C and 220 &deg, C hydrothermal treatments. Considering the latest observation, hydrothermal treatment at 220 &deg, C is a preferable option for the valorization of residual strawberry extrudate (RSE) due to the high solubilization of valuable phenolic compounds that can be recovered.

21 Páginas.-- 1 Tabla.-- 2 Figuras, This review summarizes and critically analyzes the different types of potential valorization options for strawberry extrudate in order to have a broader overview of the potential management of this waste. Animal feed is commonly used as a management option for the strawberry extrudate; however, most of the strawberry extrudate is disposed in landfills. Strawberry extrudate contains different bioactive compounds that encourage the use of an alternative management approach than landfilled. The present review offers a complete comparative, including the advantages and drawbacks of each reviewed technique, to facilitate the selection of the most suitable technology for the different valorization scenarios. This review has been structured in three sections: 1. Composition of the strawberry extrudate and strawberry especially focused on their content in bioactive compounds. 2. The different techniques of extraction and purification of bioactive compounds. 3. The handling and management of the resulting biomass after the extraction process of bioactive compounds., This research was funded by the Spanish Ministry of Economy and Competitiveness by Project CTM2017-83870R. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).

31 Páginas .-- 5 Figuras.-- 6 Tablas, This study proposes a biorefinery approach system to treat two berry extrudates generated by the berry-tasted products industry. The berry extrudates studied were strawberry extrudate (SE1 and SE2) and raspberry extrudate (RE), both of them processed in the same industrial plant. The proposed biorefinery approach consists in the extraction of bioactive compounds after hydrothermal pre-treatment followed by anaerobic digestion of the remaining biomass after extraction. A high concentration of valuable phenolic compounds was extracted from each extrudate through the absorption-desorption processes, i.e. 876, 392 and 2402 mg of gallic acid equivalents/kg extrudate in SE1, SE2 and RE, respectively. Anaerobic digestion of the remaining biomass after extraction led to high methane production, between 371 and 503 mL CH4/g VS. The economical evaluation showed that the proposed biorefinery approach would offer higher benefits than just anaerobic digestion of the untreated extrudate, although this last option would be economically feasible as well., The authors are very grateful to the Spanish Ministry of Economy and Competitiveness for funding this research through the project CTM2017-83870-R and the Ministry of Economy and Competitiveness Ramon y Cajal Programme (RyC 2012-10456). The authors also wish to thank to Dr. Bernabé Alonso-Fariñas for the revision of the manuscript.