Maria Paula Cardeal Volpi

Macauba palm ( Acrocomia spp.) is a perennial, fruit‐bearing plant native to tropical and subtropical regions of the Americas, predominantly found in South and Central America. Belonging to the Arecaceae family, it thrives in diverse climatic conditions and is characterized by its oil‐rich fruits, suitable as feedstock to produce various biofuels. Within Acrocomia genus, species such as Acrocomia aculeata , Acrocomia totai , and Acrocomia intumescens are of industrial interest due to their potential role in energy production. This study presents a bibliometric analysis of scientific research focused on macauba biomass, emphasizing their potential applications in bioenergy and value‐added byproduct development. The analysis was conducted using RStudio and Bibliometrix, based on data retrieved from the Scopus and Web of Science databases. The resulting bibliometric data allowed for a detailed evaluation of material characterization and emerging research trends, highlighting a growing interest in biofuel production or other products, particularly biodiesel, sustainable aviation fuel (SAF), and biochar, within Brazil and South America countries. Among the byproducts of oil extraction, the residual cake from the pulp and kernel have been widely studied, especially for applications in animal, human nutrition and adsorbents for pollutant removal. The endocarp has attracted crescent attention for production of biochar and adsorbent materials for heavy metals remediation. Over the past decade, research has also expanded to previously underexplored components such as the epicarp (husk) and leaves, revealing their potential as a secondary lipid source and raw material for biochar, briquettes, and enzymatic processes. Recent studies point out the mass distribution of macauba fruit components is approximately 22.6% epicarp (husk), 42.6% mesocarp (pulp), 28.4% endocarp, and 6.4% kernel. The diversity of biomass fractions and transformation routes underscores the significant potential of macauba and its residues to support the bioeconomy through the development of biofuels, adsorbents, and other high‐value bioproducts.

This scientific paper provides an overview of the current state of pyrolysis in Europe, with a focus on mapping the key research areas and technologies employed. This research relied on search equations that centered on the utilization of biomass and plastics as primary feedstocks in pyrolysis, with a particular emphasis on biochar generation and different technologies applied. The results showed that both plastic and biomass pyrolysis can contribute to reducing waste and mitigating greenhouse gas emissions. However, plastic pyrolysis can release harmful pollutants due to the presence of chlorine and other additives in plastics, which requires sophisticated emission control systems to be implemented. The production of biochar from sewage sludge is identified as a promising approach for phosphorus recovery, which can subsequently be utilized as a valuable fertilizer in agricultural applications. The data from this study contribute to exploring future applications at pilot and industrial scales for pyrolysis, with a critical assessment of the use of feedstocks. Moreover, this work provides information about current companies that are already operating on a large scale with pyrolysis and a map of the principal countries in Europe engaged in pyrolysis research, correlating the characteristics of the pyrolysis processes investigated.

Coffee processing generates a large amount of organic waste, which has the potential for energy use through biogas production. Although Brazil dominates world coffee production, treating its residue with biogas technology is not a practice, especially due to this product’s seasonality, which hampers continuous digester operation. The implementation of biogas production from coffee residues in a concept of industrial symbiosis could overcome this. This work evaluates the biogas energy potential from the main liquid residues of coffee processing (i.e., mucilage and wash water) and their integration with glycerin and cattle manure. Around 2773 m³ biogas day⁻¹ would be produced (75% CH₄), used as biomethane (734 thousand m³ year⁻¹), or thermal energy (23,000,000 MJ year⁻¹), or electricity (2718 MWh year⁻¹), which could supply, respectively, all the liquefied petroleum gas (LPG) and diesel demands of the farm, all the thermal energy demands of the grain drying process, as well as electricity for 30 residences. Considering the short coffee season, the results have a broader context for the application of biogas production on coffee processing farms, envisaging that the Agroindustrial Eco-Park concept has the potential to integrate various agroindustrial sectors for energy production, residue exchange, and water recirculation.

Anaerobic digestion (AD) of residues from integrated first- and second-generation ethanol (1G2G) biorefineries is a sustainable method for energy recovery through biogas production. This study evaluated the co-digestion of 1G vinasse, 2G vinasse and pentose liquor (from the pretreatment of sugarcane bagasse for 2G ethanol production) compared to individual digestions using biochemical methane potential (BMP) assays. The results showed some “key” micronutrients from the substrates that affected methane (CH₄) production, while their balance provided by co-digestion achieved high digestibility (95%). High iron (Fe) and nickel (Ni) concentrations, in addition to furfural (0.33 g L⁻¹) in pentose liquor seemed to decrease its CH₄ production potential. Despite these adverse effects observed in mono-digestion, co-digestion was beneficial for this substrate, increasing digestibility (52%) and BMP (118%). The highest BMP was observed in vinasse 2G (631 ± 6 NmL CH₄ gTVS⁻¹), with no significant difference compared to the adjusted modified Gompertz model (624 ± 10 NmL CH₄ gTVS⁻¹). The co-digestion system also presented the highest specific CH₄ production rate (20 ± 1 NmL CH₄ gTVS⁻¹day⁻¹) and shortened the lag phase by 19% compared to the AD of isolated 1G vinasse with the second lowest BMP value (494 ± 11 NmL CH₄ gTVS⁻¹).

The present work proposes the optimization of the co-digestion of vinasse, filter cake, and deacetylation liquor in a continuous reactor by adding iron(III) oxide (Fe₃O₄) nanoparticles (NPs), comparing the results with a previous reactor operation without NPs. Initially, tests were carried out in batches with different NP concentrations, resulting in 5 mg L⁻¹ as the best concentration to be added in the continuous reactor along the increments of the applied organic load rate (OLR). Methane (CH₄) production reached a maximum value of 2.8 ± 0.1 NLCH₄ gVS⁻¹ (normal liter methane per gram of volatile solids), and the organic matter removal reached 71 ± 0.9% in phase VI (OLR of 5.5 gVS L⁻¹ day⁻¹). This production was 90% higher than the reactor co-digestion operation without NPs. The anaerobic digestion (AD) development was stable with stable organic acid (OA) concentrations, indicating the predominance of the propionic acid route to produce CH₄. The main methanogenic Archaea identified was Methanoculleus, indicating that the predominant metabolic route was that of acetate (SAO) coupled with hydrogenotrophic methanogenesis. The use of Fe₃O₄ NPs managed to improve the AD from the first-generation and second-generation (1G2G) ethanol production residues and stimulated microbial community growth, without modifying the preferable metabolic pathways.

Recently, new solutions have arisen to promote bioenergy expansion, some of which meet the requirements of reliability, sustainability, and governance. In Brazil, the Sao Paulo state (SPS) is characterized by strong agro‐industrial and livestock activities, which generates increasing residues in the last years with the potential to produce bioenergy and offer environmental and economic benefits. The Brazilian National Biofuel Policy (Renovabio) has been enhanced to seek sustainable development, encouraging new agribusiness research. Studies have shown that the sugarcane sector, a conventional ethanol and bioelectricity producer, has the greatest potential to produce biogas/biomethane, which can be maximized with the introduction of co‐substrates regionally generated from corn, soy, orange, coffee, poultry, and swine. This overview, based on the main SPS agro‐industrial and livestock residues, shows innovative alternatives for integrating anaerobic co‐digestion (co‐AD) processes through a regional strategy, by providing long‐term revenues and greenhouse gas mitigation, which would also spread the discussion for National and International prospects. This study discusses logistical, political, and financial aspects, revealing a promising business model supported by public policies. However, its feasibility requires a real economic assessment with the inclusion of decarbonization credits, and political subsidies for biomethane as a biofuel under the Renovabio, which will facilitate its insertion into the agro‐industry in the coming years.This article is categorized under: Policy and Economics > Energy Transitions Sustainable Energy > Bioenergy Climate and Environment > Circular Economy Policy and Economics > Regional and International Strategies

The proteomics analysis could contribute to better understand about metabolic pathways in anaerobic digestion community because it still as a “black-box” process. This study aimed to analyze the proteins of the anaerobic co-digestion performed in reactors containing residues from the first and second generation ethanol production. Metaproteomics analysis was carried out for three types of samples: anaerobic sludge without substrate (SI), semi-continuous stirred reactor (s-CSTR) with co-digestion of filter cake, vinasse, and deacetylation liquor (R-CoAD) and s-CSTR with co-digestion of these aforementioned residues adding Fe₃O₄ nanoparticles (R-NP). The R-CoAD reactor achieved 234 NmLCH₄ gVS⁻¹ and 65% of CH₄ in the biogas, while the R-NP reactor reached 2800 NmLCH₄ gVS⁻¹ and 80% of CH₄. The main proteins found were enolase, xylose isomerase, pyruvate phosphate dikinase, with different proportion in each sample, indicating some change in pathways. However, according to those identified proteins, the main metabolic routes involved in the co-digestion was the syntrophic acetate oxidation coupled with hydrogenotrophic methanogenesis, with the CH₄ production occurring preferentially via CO₂ reduction. These findings contributed to unravel the anaerobic co-digestion at a micromolecular level, and may select a more appropriate inoculum for biogas production according to that residue, reducing reaction time and increasing productivity.

The co-digestion of residues from the sugarcane industry has already proven to be a highly attractive process for biogas production through anaerobic digestion (AD). The use of residues such as vinasse (1G) filter cake (1G) and deacetylation liquor (2G) in CSTR operation showed the potential for integrating 1G and 2G ethanol biorefineries through AD in previous work by our research group. The use of nanoparticles (NP) is a favorable way to optimize AD processes, as these additives allow the introduction of nutrients to the process more assertively concerning the distribution and interaction with microorganisms. The present work proposed the optimization of the co-digestion of vinasse, filter cake, and deacetylation liquor in a continuous reactor by adding Fe ₃ O ₄ NP, comparing the results with a previous reactor operation without NP. Initially, tests were carried out in batches with different NP concentrations, resulting in 5 mg L ^{- 1} as the best concentration to be added in the continuous reactor along the increments of the applied organic rate load (ORL). CH ₄ production reached a maximum value of 2.8 ± 0.1 NLCH ₄ gVS ^-1 and the organic matter removal reached 71 ± 0.9%, in phase VI (ORL of 5.5 gVS L ^-1 day ^-1 ). This production was 90% higher than the reactor co-digestion operation without NP. The pH and alkalinity results indicated the methanogenesis stabilization within 60 days of operation: 30 days before when there was no NP added. The AD development was stable, presenting low variations in the oxidation-reduction potential (ORP) and stable organic acid (OA) concentrations, which indicated the propionic acid route to produce CH ₄ was predominant. The main methanogenic Archeae identified was Methanoculleus , indicating that the predominant metabolic route was that of acetate (SAO) coupled with hydrogenotrophic methanogenesis. The use of Fe ₃ O ₄ NP managed to improve the AD from the 1G2G ethanol production residues and stimulated the microbial community growth, not modifying the preferable metabolic pathways.

This work performed co-AD from the vinasse and filter cake (from 1G ethanol production) and deacetylation liquor (from the pretreatment of sugarcane straw