Search Results (57)

Anaerobic co-digestion (AcoD) is a promising strategy to enhance biogas production and improve the sustainability of wastewater treatment plants (WWTPs). However, information regarding process scale-up and reactor performance following the interruption of co-substrate feeding remains limited. This study evaluated the anaerobic co-digestion of municipal mixed sludge (MMS) and fruit and vegetable peel purées (FVPP) in a 10.6 L semi-continuously fed continuously stirred tank reactor (CSTR), operating under conditions representative of municipal WWTP anaerobic digesters. Mono-digestion (AMD) and co-digestion (AcoD) assays were conducted under mesophilic conditions and assessed through process performance indicators. AcoD increased methane concentration from 58.50% to 60.75%, while total volatile solids (TVS) removal efficiency increased from 41.67% to 59.84% in comparison with AMD. Total chemical oxygen demand (COD_T) removal efficiency also improved from 40.82% to 56.48%. Furthermore, H₂S concentrations decreased from approximately 350 ppmv during mono-digestion to 7 ppmv during co-digestion. An additional mono-digestion trial (aAMD) performed after co-substrate withdrawal achieved the highest specific methane production (0.27 L CH₄/g⁻¹ TVS) and organic matter removal efficiencies (63.73% for TVS and 67.55% for COD_T, respectively). These results demonstrate that co-digestion of MMS and FVPP improves methane quality, enhances organic matter removal, and reduces H₂S emissions, while maintaining stable reactor performance under scale-up conditions and after the interruption of co-substrate feeding. Full article

Anaerobic co-digestion (AcoD) is increasingly applied in sewage-sludge management and organic-waste treatment because it can improve methane recovery, stabilize mixed substrates, and reduce life-cycle greenhouse-gas emissions under appropriate feedstock and operating conditions. However, existing reviews still focus mainly on feedstock types or isolated enhancement measures and less often connect synergistic mechanisms with engineering implementation and carbon outcomes. The specific novelty of this review is to connect functional feedstock classification, mechanism boundaries, engineering controls, and carbon-performance evaluation within one sludge-centered AcoD framework. This review synthesizes recent progress in AcoD of sewage sludge, food waste, livestock manure, crop residues, and industrial organic streams through a chain from feedstock traits to substrate interactions, microbial responses, engineering performance, and carbon benefits. Feedstocks are reorganized by function rather than by waste name, highlighting how carbon-to-nitrogen contrast, buffering capacity, hydrolysis recalcitrance, and inhibitor profiles jointly define synergy potential. Key mechanisms, including C/N balancing, hydrolysis complementarity, inhibitor mitigation, and direct interspecies electron transfer (DIET), are discussed together with their applicability limits. Representative evidence shows methane-yield or methane-production increases of about 41–55% for selected food-waste–manure blends, approximately 45% for rice–straw–pig manure systems after cellulolytic pretreatment, and approximately 16–55% for selected additive strategies; these values are illustrative rather than directly comparable because the underlying studies differ in substrates, baselines, reactor configurations, pretreatment conditions, and operating parameters. The review then translates mechanism into practice through pretreatment, reactor-selection templates, operating windows, additive reinforcement, and artificial-intelligence-assisted monitoring. Representative cases and life-cycle evidence indicate that AcoD can improve methane productivity while lowering greenhouse-gas emissions relative to landfill or mono-digestion pathways when energy substitution and nutrient recycling are credibly counted. Remaining bottlenecks include incomplete kinetic integration, limited DIET quantification, insufficient reporting of quantitative operating ranges and additive dosages, and weak coupling of carbon, economics, and regional feedstock dynamics. The revised review therefore treats AcoD as a sludge-centered mechanism-to-engineering framework and highlights two transferability gaps that require stronger standardization: biodegradation/toxicity testing and local co-substrate logistics. Full article

In municipal wastewater treatment plants (WWTPs), anaerobic digestion of municipal mixed sludge (MMS) often yields low energy recovery and operational instability due to imbalances between primary and secondary sludges. Anaerobic co-digestion (AcoD) with readily biodegradable wastes, such as fruit and vegetable waste (FVW), can enhance process stability and biogas production. Life cycle assessment (LCA) methodology is used in this study to evaluate the environmental performance of implementing AcoD of MMS and FVW in a municipal WWTP, compared with a business-as-usual scenario combining mono-digestion of MMS and incineration of FVW. The LCA was modelled in openLCA 2.5 using the ecoinvent 3.9.1 database (cut-off allocation approach), and impacts were assessed with the ReCiPe 2016 Midpoint (H) method, focusing on climate change, terrestrial acidification, fossil fuel depletion, and marine eutrophication. Results indicate that AcoD reduces impacts across all environmental categories, mainly due to higher biogas yields that increase on-site electricity generation and decrease reliance on grid electricity. Improved total solids removal also lowers digestate production and composting-related burdens. Electricity consumption remains the main hotspot in both scenarios, highlighting the importance of energy efficiency and electricity mix. Sensitivity analysis on methane content (61–65% v/v) confirms the robustness of AcoD’s environmental benefits. Full article

The management of Pig Slurry (PS) and Wine Vinasse (WV) poses major environmental and economic challenges, Anaerobic co-digestion (AcoD) offers a promising approach, producing both renewable energy and nutrient-rich digestates with agronomic potential. This study evaluated digestates obtained from the AcoD of a 50:50 mixture of pig slurry and wine vinasse under Temperature-Phased Anaerobic Digestion (TPAD) conditions. The acidogenic reactor reached stability at a hydraulic retention time (HRT) of 5 days, achieving 51.34 ± 3.08% of tCOD removal and approximately 0.5 L of daily green hydrogen production, whereas the methanogenic stage reached stability at an HRT of 10 days with 89.14 ± 2.33% tCOD removal and recording daily biomethane production of up to 1 L. Digestates were tested in germination assays using Lepidium sativum (garden cress), Lactuca sativa (lettuce), and Raphanus sativus (radish) seeds to assess phytotoxicity, and pathogen analyses were conducted to confirm sanitary safety (contains 0.8 × 10³ MPN/gTS E. coli). Results showed that agronomic performance was primarily influenced by dilution level, at 10D–15D% dilutions, germination and root growth remained stable, with Germination Index (GI) values above 80%. In contrast, concentrations above 25D% led to marked inhibition, with GI values below 50%. These findings demonstrate that the TPAD system operates effectively when treating pig slurry and winery vinasse, producing digestates that are safe and effective organic amendments. Moreover, given their compliance with sanitary standards, these digestates can be classified as Class A biosolids suitable for agricultural application, provided that adequate dilution is ensured. Full article

The cause of chronic neurological effects associated with Lyme disease (LD) remains unclear. We propose that bacterial extracellular vesicles (BEVs) released by Borrelia burgdorferi, the causative agent of LD, exacerbate spirochete-induced damage and serve as a persistent source of antigenic stimulation. We showed that, over a 10-day period, in vitro cultures of B. burgdorferi B31 produced 38,000 BEVs per spirochete with a distinctive double-membrane structure and median diameter of 143.3 nm. BEVs contained known immunogenic and immunomodulatory molecules such as peptidoglycan, p66, flagellar filament protein (FlaB), basic membrane proteins A/B/D, BdrV, GroEL, CRASP-1, ErpA8, glycerophosphodiester phosphodiesterase, p37, OMS28, p13, OspA/B/C, VlsE, and outer membrane glycolipids (e.g., cholesteryl 6-O acyl beta D galactopyranoside). Chromosome-encoded 16S ribosomal RNA and cp32 plasmid-encoded OspE and terminase genes were also detected in the BEVs. Of the 45 Borrelia proteins identified in the urine of a C3H/HeJ murine model of Lyme disease, 14 were associated with BEVs. In human urine samples, 31 of 289 spirochete proteins detected in patients with either acute Lyme disease or persistent borreliosis post-treatment symptoms, including p66 and FlaB, were also BEV-associated. BEV treatment of HMC3 human microglial cells reduced phagocytic activity and triggered aberrant activation of inflammatory and immunometabolic pathways, including upregulation of interferon-alpha (IFN-α), aconitate decarboxylase 1 (Acod1), and Toll-like receptor 2 (TLR2) gene expression. BEVs also induced NRF2 nuclear translocation. In conclusion, these findings support that BEVs can amplify spirochete-induced damage and act as antigenic debris, driving dampened phagocytic activity and dysregulated inflammation, with implications for diagnostics and therapeutics targeting vesicle-mediated pathology. Full article

Background: Tumor-associated neutrophils (TANs) exhibit remarkable functional plasticity within tumor microenvironment (TME), with N1-like subtypes promoting anti-tumor immunity and N2-like subtypes facilitating tumor progression. Despite their critical role in cancer immunology, strategies to selectively modulate TAN polarization remain limited. Methods: We integrated transcriptomic analyses of TAN subtypes to identify potential hub molecules. Molecular docking and experimental assays were used to evaluate DHA’s effect on neutrophil-like cell polarization. Results: Hub genes (TNF, IL1B, PTGS2, BCL2A1, MSR1, ACOD1, CXCL16, CLEC10A, and SOCS3) were identified, with TNF serving as a potential core regulator. Molecular docking indicated that DHA forms stable interactions hub proteins. Experimentally, DHA treatment of neutrophil-like dNB4 cells promoted N1 polarization, evidenced by upregulation of TNF, IL1B, PTGS2, BCL2A1, MSR1, ACOD1, CXCL16, and N1 markers PD-L1 and NOX2, and downregulation of N2 marker CEACAM8 and hub genes CLEC10A and SOCS3. Functional assays demonstrated that DHA-treated cells exhibited increased secretion of TNF, IL1β, ROS, and PD-L1, accompanied by enhanced cytotoxic activity against hepatocellular carcinoma cells in a co-culture system. Conclusions: These findings reveal the molecular mechanisms underlying TAN polarization, and establish DHA as a potent immunomodulatory agent capable of reshaping TANs toward an anti-tumor phenotype. Full article

Brazil is one of the world’s largest producers of grains and cattle, activities that generate a large amount of organic waste, which has high potential for biogas and methane production. Cattle manure (CM) and industrial waste from corn processing are substrates with significant potential for biogas and methane generation, particularly through the process of anaerobic co-digestion (AcoD). This study aimed to assess the biogas and methane yield, as well as the stability of the AcoD process involving CM and corn grain residues (CG) derived from a grain processing agroindustry, in conjunction with the application of an enzyme complex. The experiment was conducted in plug-flow biodigesters, with a total volume of 28 L, under a semi-continuous feeding regime (OLR = 0.84 g vs. L d⁻¹) at ambient temperature. The findings indicated increases in daily biogas and methane production for AcoD, without the addition of enzymes, of 52.1% and 44.4%, respectively, in comparison to CM mono-digestion. The incorporation of the enzyme complex did not yield beneficial effects, irrespective of the substrate composition. The utilization of enzymes in semi-continuous biodigesters to enhance methane yields necessitates further investigation to achieve favorable outcomes and validate its efficiency. Full article

Artificial intelligence (AI) has emerged as an innovative approach to the computer modeling and optimization of anaerobic digestion (AD) and anaerobic co-digestion (AcoD) processes. AI-based algorithms are ideally suited to capture the complex nonlinear behavior of these processes. Compared to conventional methods and models, AI-based algorithms have made modeling these processes much easier. Various AI algorithms, including multivariate statistical analyses, tree-based machine learning, nature-inspired optimization, support vector machine, and artificial neural networks (ANN) have been widely used to model the AD and AcoD processes. Researchers have successfully used stand-alone and hybrid ANMs to predict biogas yield and composition, as well as for efficient process monitoring and control. Furthermore, the development of advanced optimization algorithms, including genetic algorithms and particle swarm optimization, helps to optimize the ratio of mixing of co-substrates in AcoD and important process parameters (i.e., temperature (T), pH, retention time, total solids and volatile solids). This review discusses AI applications for AD and AcoD process modeling, optimization, prediction of unknown parameters and variables, and real-time monitoring and control. A critical comparison is made with some of the popular mathematical models and algorithms for monitoring and optimization designed on their basis. The review presents also future research directions in this area and some of our own results. Full article

The global demand for processed foods has increased reliance on synthetic phenolic antioxidants (SPAs), including tert-butylhydroquinone (TBHQ), a widely used additive to prevent lipid oxidation and extend shelf life. TBHQ is considered safe at present regulated levels; however, studies suggest potential adverse effects, including oxidative stress, genotoxicity, and impacts on immune function, raising concerns about human health and ecological risks. Herein, we investigated the immunomodulatory effects of TBHQ on RAW 264.7 murine macrophages pre-exposed to 0.1, 1, and 5 µM TBHQ and then stimulated with lipopolysaccharide (LPS) or polyinosinic-polycytidylic acid (poly I:C, PIC) to model bacterial and viral immune challenges. We then used functional assays and transcriptomic profiling to assess inflammatory responses and oxidative stress signaling. TBHQ reduced nitric oxide production and IL-10 secretion at the highest non-cytotoxic dose, and enhanced phagocytosis and IL-6 secretion at the lowest concentrations. Overall, transcriptomics revealed significant downregulation of proinflammatory pathways and induction of glutathione and xenobiotic metabolism. Pre-treatment with TBHQ increased gene transcript counts of key metabolic genes/transporters such as Cbr3, Adh7, Gstp1/3, Gsta3, Hmox1 and Gclm. Following treatment with LPS or PIC several genes for classical proinflammatory chemokines and cytokines such as Cxcl2, Ccl2, Ccl12, Acod1, Ptgs2, Nos2, and Il6 were downregulated. Genes involved in NF-κB signaling, such as Nfkbia, Nfkb1, and Ikbke were also downregulated. Our study suggests that the induction of Nrf2-related antioxidant pathways by TBHQ is the main driver for reduced inflammatory signaling in macrophages. Full article

One of the most interesting applications of crude glycerol (CG) is its use for biogas production via the anaerobic co-digestion (AcoD) process. The main aim of the current study was to provide a comprehensive review on the performance of the AcoD of CG mixed with various substrates. For this purpose, analyses were performed for studies available in the literature wherein one-stage experiments were conducted. To the best of the authors’ knowledge, the present study is the first one which demonstrates an analysis of the main parameters of CG and substrates (e.g., animal manure, sewage sludge, cattle manure and food waste) used for AcoD. Moreover, a detailed analysis of the impact of selected parameters on AcoD performance was carried out. It is demonstrated that the values of key parameters characterizing the CG used for AcoD were within wide ranges. This can be explained by the fact that the composition of CG depends on many factors; for instance, these include the source of oil used for biodiesel production, processing technology, the ratio of reactants, the type of catalyst and the procedure applied. Moreover, performing a literature review allowed us to demonstrate that adding CG to feedstock caused the enhancement of process performance compared to results obtained for mono-digestion. Additionally, it was shown that, in general, increasing the concentration of CG in feedstock led to improvement of the biogas yield; however, a potential inhibitory effect should be considered. Analysis of data available in the literature allowed us to indicate that for most of the experiments performed, a methane (CH₄) content in biogas higher than 60% was obtained for CG content in feedstock up to 8% v/v. In addition, it is demonstrated that in order to evaluate the performance of AcoD performed under thermophilic conditions, more studies are required. Finally, it should be pointed out that the present study provides considerable insight into the management of CG. Full article

The brewing industry generates significant organic waste, much of which remains underutilized despite its potential for energy recovery. This study assesses the feasibility of anaerobic co-digestion (AcoD) using brewers’ spent grain (BSG) from the craft beer production process and cattle manure from feedlots. Thermogravimetric analysis confirmed similar volatile solids content in both substrates, validating BSG as a viable feedstock. AcoD trials were conducted in 20 L biodigesters under dry and ambient conditions over 40 days. Methane yields reached 25 mL CH₄ gVS⁻¹ at a 1:1 inoculum–substrate ratio fresh matter basis and 67.33 mL CH₄ gVS⁻¹ at 2.5:1, indicating that higher inoculum levels enhance methane production. Kinetic modeling using Modified Gompertz, Logistic, and other microbial growth-based models showed that the Logistic model best represented the methane production trends. The detection of hydrogen sulfide in the biogas emphasizes the need for effective filtration. Overall, this work highlights AcoD as a promising approach for organic waste valorization and renewable energy generation in the craft brewing sector, supporting circular economy practices and contributing to environmental and economic sustainability. Full article

In rural Ghana, limited access to affordable, clean cooking fuels drives the need for decentralised waste-to-energy solutions. Anaerobic co-digestion (AcoD) offers a viable route for transforming organic residues into renewable energy, with the added benefit of improved process stability resulting from substrate synergy. This study aims to evaluate the technical feasibility and stabilisation challenges of AcoD, using locally available fruit waste and beet molasses at a secondary school in Bedabour (Ghana). Biological methane potential (BMP) assays of different co-digestion mixtures were conducted at two inoculum-to-substrate (I/S) ratios (2 and 4), identifying the highest yield (441.54 ± 45.98 NmL CH₄/g VS) for a mixture of 75% fruit waste and 25% molasses at an I/S ratio of 4. Later, this mixture was tested in a 6 L semi-continuous AcoD reactor. Due to the high biodegradability of the substrates, volatile fatty acid (VFA) accumulation led to acidification and process instability. Three low-cost mitigation strategies were evaluated: (i) carbonate addition using eggshell-derived sources, (ii) biochar supplementation to enhance buffering capacity, and (iii) the integration of a bioelectrochemical system (BES) into the AcoD recirculation loop. The BES was intended to support VFA removal and enhance methane recovery. Although they temporarily improved the biogas production, none of the strategies ensured long-term pH stability of the AcoD process. The results underscore the synergistic potential of AcoD to enhance methane yields but also reveal critical stability limitations under high-organic-loading conditions in low-buffering rural contexts. Future implementation studies should integrate substrates with higher alkalinity or adjusted organic loading rates to ensure sustained performance. These findings provide field-adapted insights for scaling-up AcoD as a viable renewable energy solution in resource-constrained settings. Full article

Osteoclasts, which are derived from myeloid precursors, are essential for physiologic bone remodeling but also mediate pathological bone loss in inflammatory diseases such as periodontitis and rheumatoid arthritis. Lysine-specific demethylase (LSD1/KDM1A) is a histone demethylase that modulates the chromatin landscape via demethylation of H3K4me1/2 and H3K9me1/2, thereby regulating the expression of genes essential for deciding cell fate. We previously demonstrated that myeloid-specific deletion of LSD1 (LSD1LysM-Cre) disrupts osteoclast differentiation, leading to enhanced BV/TV under physiological conditions. In this study, we show that LSD1LysM-Cre female mice are similarly resistant to inflammatory bone loss in both ligature-induced periodontitis and K/BxN serum-transfer arthritis models. Bulk RNA-seq of mandibular-derived preosteoclasts from LSD1LysM-Cre mice with ligature-induced periodontitis revealed the upregulation of genes involved in inflammation, lipid metabolism, and immune response. Notably, LSD1 deletion blocked osteoclastogenesis even under TGF-β and TNF co-stimulation, which is an alternative RANKL-independent differentiation pathway. Upregulation of Nlrp3, Hif1α, and Acod1 in LSD1LysM-Cre preosteoclasts suggests that LSD1 is essential for repressing inflammatory and metabolic programs that otherwise hinder osteoclast commitment. These findings establish LSD1 as a critical epigenetic gatekeeper integrating inflammatory and metabolic signals to regulate osteoclast differentiation and bone resorption. Therapeutic inhibition of LSD1 may selectively mitigate inflammatory bone loss while preserving physiological bone remodeling. Full article

Pig slurry (PS) and wine vinasse (WV) pose environmental risks if not properly managed. Their composition makes them suitable for anaerobic co-digestion (AcoD), enhancing biomethane production and improving organic matter degradation efficiency. This research applies an innovative Design of Experiments (DoE) approach—specifically the Box–Behnken design (BBD)—to systematically optimize the AcoD process, surpassing traditional single-factor methods by efficiently evaluating the interactions. Variables such as temperature (35 °C, 52.5 °C, 70 °C), substrate ratio (25PS:75WV, 50PS:50WV, 75PS:25WV) and pH (7, 7.5, 8) were tested using a Box–Behnken design which studied the correlations between the experimental data and the model. In fact, the results showed that temperature, ratio, and their interaction significantly influenced biomethane production, being the pH the factor with the least influence on the response. Optimal conditions—pH of 8, temperature of 35 °C and a 50:50 substrate ratio—achieved a biomethane yield of 487.94 CH₄/gVS (Volatile Solids). These results demonstrate the effectiveness of the DoE methodology in maximizing biomethane production and represent a significant advancement in valorizing wastes from pig farms and wineries, promoting a circular and sustainable economy. Full article

Anaerobic digestion (AD) offers a sustainable solution by treating biodegradable waste while recovering bioenergy, enhancing the share of renewable energy. Thus, this study aims to investigate the AD for managing and valorizing residues from the potato chip industry: potato peel (PP), potato offcuts (OC), waste cooking oil (WCO), wastewater (WW), and sewage sludge (SS). In particular, the biochemical methane potential (BMP) of each residue, anaerobic co-digestion (AcoD), and greenhouse gas (GHG) emissions of an AD plant are assessed. WW, OC, and SS present a BMP of around 232–280 NmL_CH4/kg of volatile solids (VS). PP and WCO reach a BMP slightly lower than the former substrates (174–202 NmL_CH4/g_VS). AcoD results in methane yields between 150 and 250 NmL_CH4/g_VS. An up-scaled anaerobic digester is designed to manage 1.60 Mg/d of PP. A residence time of 12 days and a digester with 165 m³ is estimated, yielding 14 Nm³_CH4/Mg_VS/d. A simulated AD plant integrated with a combined heat and power unit results in a carbon footprint of 542 kg of CO₂-eq/Mg_db PP, primarily from biogenic GHG emissions. These findings highlight the potential of AD to generate renewable energy from potato industry residues while reducing fossil fuel-related GHG emissions and promoting resource circularity. Full article