Structural instability poses a major challenge for the scale-up of horizontal plug-flow reactors treating high-solids kitchen waste. This study systematically optimized stirring systems across 12, 100, and 1000 m3 scales using fluid-structure interaction (FSI) and finite element analysis (FEA). Comparative analysis identified C45 steel as the optimal structural material, outperforming the premium 316 L stainless steel by offering a 5% higher elastic modulus to reduce shaft deformation and increasing the structural safety factor by 14.5%. Furthermore, hollow shaft inner diameters were optimized to 90, 160, and 180 mm, respectively. Crucially, support configurations exhibited scale dependence: a single support sufficed for smaller volumes, whereas a three-support configuration was essential for the 1000 m3 reactor to meet stiffness requirements. Additionally, wet modal analysis revealed a unique hydrodynamic stiffening effect, confirming a minimum critical speed of 55.41 rpm to ensure a robust safety margin against resonance. These findings successfully elevate qualitative engineering intuition into quantitative design guidelines, establishing a reliable framework for the structural optimization and scale-up of high-solids anaerobic reactors.

From the perspective of linking structural damage, oxidative stress and molecular regulation, this study clarified how antibiotic inhibited nitrogen metabolism in aerobic granular sludge (AGS). Long-term antibiotic stress severely damaged AGS structure, causing blurred boundaries, surface cracks and collapse zone. As a primary response, AGS continuedly increased extracellular polymeric substances (EPS) secretion, which partially mitigated antibiotic toxicity through adsorption and shielding effects. However, persistent toxicity triggered 160.2% higher reactive oxygen species (ROS) level than the control. Excessive ROS disrupted cellular redox homeostasis and suppressed the activities of nitrogen-transforming key enzymes (e.g., AMO, NOR, NR, NIR) with an inhibition range of 22.4∼31.9%, and energy metabolism enzymes responsible for ATP synthesis with a 40.2% activity reduction. Furthermore, this oxidative stress cascade extended to the central carbon metabolism, as nearly all genes encoding tricarboxylic acid (TCA) cycle enzymes were remarkably downregulated. This TCA cycle inhibition further cut off the supply of ATP and some electron donors (e.g., NADH and FADH2) essential for nitrification and denitrification, forming a self-reinforcing inhibitory loop. Overall, this study demonstrated that antibiotics inhibit AGS nitrogen transformation through a well-defined "oxidative stress-energy metabolism-functional gene" cascade mechanism.

Anaerobic mono-digestion of municipal organic wastes (MOW) is often constrained by acidification or recalcitrance. This study investigated the ternary co-digestion of food waste (FW), fallen leaves (FL), and sewage sludge (SS) to unlock synergistic potentials. Kinetic analysis in batch assays showed that the ternary mixture (FW:FL: SS = 3:1:2) achieved the highest Co-digestion Performance Index (CPI) of 1.98. Statistical analysis revealed that within the optimal C/N window, while buffering capacity and C/N ratio are intrinsically linked through substrate supplementation, the degree of synergy was more directly sensitive to the resulting buffering capacity (evidenced by a stabilized FOS/TAC ratio) than to the exact C/N ratio. FL and SS provided essential alkalinity, successfully mitigating the acidification failure typical of FW mono-digestion. High-throughput sequencing unveiled a distinct ecological reconfiguration: Firmicutes and Bacteroidota were associated with accelerated hydrolysis, while syntrophy between Synergistota and Chloroflexi likely maintained thermodynamic equilibrium by preventing hydrogen partial pressure buildup. Furthermore, functional redundancy between the substrate-versatile Methanosarcina (r-strategist) and the acetoclastic Methanothrix (K-strategist) facilitated high methanogenic efficiency during periods of high acidogenic fluxes. Translating these insights into engineering practice, our results validate that once the feed mixture falls within the broad optimal C/N window (10-30), continuous stoichiometric balancing becomes practically unnecessary. Instead, prioritizing the standard FOS/TAC ratio serves as a sufficient, single-parameter control strategy, offering a highly practical alternative to complex multi-variable management for the integrated valorization of urban waste streams.

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by Aβ deposition, tau hyperphosphorylation, and neuroinflammation. No effective drugs can slow disease progression. Polysaccharides from traditional Chinese medicine (TCM) exhibit neuroprotective activities (e.g., antioxidant, anti-inflammatory) with good safety. However, their clinical application is limited by low oral bioavailability, poor blood–brain barrier (BBB) permeability, and a pharmacokinetic–pharmacodynamic paradox. The emerging role of the microbiota–gut–brain axis in AD offers a strategy to overcome this paradox. This review summarizes the structural features and classification of TCM polysaccharides (from plants, fungi, and roots/rhizomes) and highlights their anti-AD mechanisms via the gut–brain axis. Acting as prebiotics, these polysaccharides escape upper digestion and are fermented by gut microbiota into short-chain fatty acids (SCFAs) and other metabolites, which enter circulation, cross the BBB, and alleviate AD pathology through metabolic, immune, and neuronal pathways. Outcomes include reduced Aβ deposition and tau phosphorylation, suppressed neuroinflammation, restored synaptic function, and improved cognition. This review provides a theoretical framework for TCM polysaccharide intervention in AD via the gut–brain axis and a pharmacological basis for developing natural product-based AD therapies.

Effective treatment of chicken manure biogas slurry (CMBS) with high suspended solids (SS) concentrations is crucial for environmental sustainability and agricultural reuse. This study investigated the combined effects of magnesium ammonium phosphate (MAP) crystallization and the addition of cationic polyacrylamide (CPAM) on SS removal from CMBS. The results indicated that using a molar ratio of Mg2+:NH4+:PO43- at the value of 1.6:1:1, achieved 60.55% SS removal, decreasing the concentration from 15,160 to 5,980 mg/L. The MAP crystals served as nucleation sites, facilitating floc aggregation, while CPAM enhanced flocculation through bridging and net trapping mechanisms. The resulting precipitates, rich in NH4+ and PO43-, can be repurposed as controlled-release fertilizers, thereby integrating nutrient recycling with wastewater treatment. This study provided a novel and efficient method for CMBS treatment, addressing the challenges posed by high SS concentrations and promoting sustainable agricultural and environmental practices.

High-solid anaerobic digestion (AD) is an effective method for treating organic solid waste. However, high solid concentrations can hinder mass transfer, leading to uneven mixing and reduced gas production efficiency. This study employs computational fluid dynamics (CFD) to simulate the multiphase (solid-liquid-gas) flow in a horizontal reactor, providing insights into its rheological properties, which can be used to optimize the structural and operating conditions of the reactor. The key factors, such as blade type, inclination angle, blade spacing, rotational speed, and solid content, are comprehensively investigated. The results suggest that an optimized combination of parameters significantly increases the area of high flow velocity within the reactor, enhancing the uniformity of solid distribution and reduces the standard deviation of concentration. However, higher solid content in the reactor expands the regions of high-solid-concentration and increases viscosity, resulting in greater energy consumption. Therefore, it is recommended to use C- or Z-type blade in reactor design. The inclination angle should be set between 10 degrees and 20 degrees, and the blade spacing should be adjusted between 250 mm and 447 mm depending on the gradient scale. Additionally, the rotational speed should be maintained between 3 and 5 rpm. These findings offer valuable guidance for designing high-solid AD reactors with good performance.

Arsenic (As) is a highly toxic chemical element associated with cardiovascular diseases and diabetes. Using genetically modified microorganisms (GMOs) for arsenic detoxification or removal is taking center stage in recent years. However, the bio-safety issue of GMOs remains an obstacle. In this study, we proposed a bioremediation process to efficiently adsorb arsenic from mining wastewater by combining a controllable GMO with biochar. One metagenomic gene element (ArsR) with high arsenic adsorption efficiency was newly identified from mining wastewater environment. Then the gene was chromosomally integrated into strain Pseudomonas putida KT2440, which is a widely used strain for environmental bioremediation. The growthregulation genetic circuit coordinating suicide gene expression was deployed onto the genome of strain KT2440. This non-auxotrophic, antibiotic-free and self-controlled programmable circuit was fine-tuned with highly sensitive perceptibility towards arsenic levels below wastewater discharge standard (< 0.50 mg/L), which made the system applicable. A biochar-microorganism coupled recovery strategy was further implemented in mining wastewater treatment, leading to increased arsenic removal capacities, which is ready for use under a circumstance up to 20 mg/L of total arsenic pollution. No more than 1.32 x 10(-9) escapee of GMOs was observed in the process, which meets the US NIH guidelines for GMOs release (<10(-8)). Thus, this study demonstrated the feasibility for arsenic bioremediation by GMOs in industrial wastewater.

Anaerobic digestion (AD) has been widely used as a promising technology for the treatment of kitchen waste (KW). The effects of several acidification-resisting methods were compared, which included the supplementation of trace elements (TEs) and zero-valent iron (ZVI) / powdered activated carbon (PAC), and the application of the sludge domesticated by acetic acid (HAc) and KW as inoculum. The results showed that the supplementation of TEs and ZVI/PAC at total solid (TS) content of 6% and optimal addition doses resulted in an increase in methane yield to 346 and 366 mL/g VS, respectively. In addition, the methane yields of 327 and 241 mL/g VS were obtained by applying the sludge domesticated with KW and HAc as inoculum, while the methane yield of the control was only 89.2 mL/g VS, representing a relative increase of 288%, 311%, 267%, and 170%. The acidification could be alleviated by applying these methods, and also the methanogenic profile was improved. Furthermore, microbial community analysis revealed that the enrichment of Methanosarcina, which enhanced the substrate utilization capacity and subsequently increased methane production, was achieved through the addition of TEs and ZVI/PAC, along with the application of sludge domesticated by KW.

BACKGROUND:Psychrophilic bacteria can survive in a unique living environment. OBJECTIVE:To explore the mechanism of low temperature adaptation and the physiological function of thermophilic metabolic genes. METHOD:Serratia marcescens strain F13 stored in microbial laboratory was cultured at 5∘C, 10∘C and 25∘C respectively, and the obtained strains were sequenced by high-throughput transcriptome. Serratia marcescens strain CAV1761 was used as the reference strain. The data produced by transcriptome sequencing were statistically analyzed by biostatistics software such as soapnuke, soap and edger. The differentially expressed genes were found based on the gene expression, and analyzed by Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis. RESULTS:The results showed that there were 718 differential genes in F13-10 vs F13-5 comparison group, 1614 differential genes in F13-25 vs F13-5 comparison group and 1636 differential genes in F13-25 vs F13-10 comparison group. GO function enrichment analysis showed that the GO term mainly enriched by different genes in the three comparison groups was mostly related to the migration and transport of cellular or subcellular components, cell localization and transmembrane transporter activity, as well as cilia or flagella dependent cell movement. In the enrichment analysis of KEGG pathway, the three comparison groups all enriched the largest number of differential genes in the branch pathway of KEGG metabolism, followed by the branch pathway of environmental information processing. CONCLUSION:In F13-10 vs F13-5, the differential genes were mainly concentrated in 20 pathways such as ATP-binding cassette transport (ABC) transporters, thiamine metabolism and flagella assembly; In F13-25 vs F13-5, the differential genes are mainly concentrated in 20 pathways, such as (ABC) transporters, arginine and proline metabolism, two-component system and so on; In F13-25 vs F13-10, the differential genes are mainly concentrated in 20 pathways such as various types of glycan synthesis, two-component system and arginine metabolism.

This study aims to comprehensively analyze the Greenhouse Gases (GHGs) emissions from current sewage sludge treatment and disposal technologies (building material, landfill, land spreading, anaerobic digestion, and thermochemical processes) based on the database of Science Citation Index (SCI) and Social Science Citation Index (SSCI) from 1998 to 2020. The general patterns, spatial distribution, and hotspots were provided by bibliometric analysis. A comparative quantitative analysis based on life cycle assessment (LCA) put forward the current emission situation and the key influencing factors of different technologies. The effective GHG emissions reduction methods were proposed to mitigate climate change. Results showed that incineration or building materials manufacturing of highly dewatered sludge, and land spreading after anaerobic digestion have the best GHG emissions reduction benefits. Biological treatment technologies and thermochemical processes have great potential for reducing GHGs. Enhancement of pretreatment effect, co-digestion, and new technologies (e.g., injection of carbon dioxide, directional acidification) are major approaches to facilitate substitution emissions in sludge anaerobic digestion. The relationship between the quality and efficiency of secondary energy in thermochemical process and GHGs emission still needs further study. Solid sludge products generated by bio-stabilization or thermochemical processes are considered to have a certain carbon sequestration value and can improve the soil environment to control GHG emissions. The findings are useful for future development and processes selection of sludge treatment and disposal facing carbon footprint reduction.

The popularization of large-scale biogas project makes the disposal of fermentative residue an urgent issue to be solved. Hydrothermal carbonization (HTC) technology is suitable for treating wet biomass to produce carbonaceous materials. In this study, the solid residue from the two-phase anaerobic digestion (AD) was hydrothermally converted in the range of 180–240 °C, and the hydrochar and aqueous components were characterized for subsequent utilization. The heating values of hydrochar were indicated to be increased by 14.2% and 16.6% at 210 °C and 240 °C as compared with feedstock, and also the specific surface areas were 34.8 m2/g and 27.1 m2/g with 17.4- and 13.3-fold enhancement, respectively. The migration of elements such as S, Cl, K to aqueous phase was beneficial for fuel application. The mesoporous pores were dominant in hydrochars with ample oxygenated functional groups. In addition, the wastewater involved organic acids, phenols, and nitrogen-containing compounds, etc. Evaluating the biodegradability by AD, it was found that when the initial concentration was ≤8 g COD/L, the maximum methane yields up to 275.9 mL CH4/g CODremoval and 277.6 mL CH4/g CODremoval were obtained. The enhanced toxicity/inhibition of representative pollutants on microorganisms was significant at higher organic loading, which could be indicated in the microbial structure and diversity. As a conclusion, the integrated production of hydrochar and methane will provide an extended route for further processing of lignocellulosic fermentative residue.

Anaerobic digestion (AD) of black liquor (BL) in papermaking is of great significance for energy recovery and environmental sustainability. Unfortunately, inhibitory compounds, such as aromatic compounds in BL hinder microbial activities if at high concentration, thus reducing the efficiency of AD. The AD experiments with different gradients of organic loading (1, 2, 4, 6, and 8 g COD/L) revealed that the maximum methane production inhibition rate of BL reached 40.74% at 2 g COD/L. A three-dimensional iron-carbon electrolysis (3D-ICE) pretreatment was performed for various time intervals (15, 30, 60, and 120 min) before AD (2 g COD/L) to explore the effect of 3D-ICE pretreatment on improving the AD efficiency. The results showed that the cumulative methane production changed from 114.10 mL CH4/g COD to 181.55, 139.40, 95.64, and 96.10 mL CH4/g COD, respectively. Moderate electrolysis (15 min) enhanced the conversion of toxic and/or refractory substances into readily degradable ones and improved the biochemical characteristics of BL by degrading the refractory nitrogenous compounds and reducing the secretion of extracellular polymeric substances. Furthermore, it was found that the dominant bacteria (e.g. Aminicenantales, Mesotoga) related to hydrolysis and fermentation of complex compounds such as aromatic compounds and acetotrophic methanogenic archaea (e.g. Methanosaeta) were significantly enriched, which was conducive to the conversion of organic matters in BL into methane. This also indicated the positive effect of 3D-ICE. Generally, 3D-ICE combined with AD is considered as an effective way to recover energy from BL.

Thermochemical process of biomass is one of the promising renewable energy technologies; however, the by-product (wood vinegar wastewater) is rich in refractory organics, which is harmful to the environment and inhibits the conversion efficiency of microorganisms. Consequently, the dominant functional microbial communities corresponding to the various substrate were obtained through the continuous domestication, and the relationship between the dominant functional communities and the degradation of organic compounds was comprehensively analyzed. The bacterial community was absolutely dominant (approximately 85%), while archaea and fungi had similar relative abundance. The diversity showed that glucose was not conducive to the development of microbial diversity, while the substrate containing wood vinegar wastewater showed the opposite trend. The functional analysis revealed that the enrichment of bacteria associated with the hydrolysis and acidification of organics increased in the domestication process. Glucose facilitated hydrogen-trophic methanogenesis as the main methanogenic pathway in the methanogenic stage.

Anaerobic digestion (AD) effectively recovers resources and reduces organic waste, but microbial activity can be inhibited by refractory compounds. The degradation efficiency in refractory wastewaters depends on the inoculum resistance to toxicity. In this study, we analyzed the relationship between substrate and dominant microbial communities by the domestication of acetate, glucose, and wood vinegar. The complex components of wood vinegar developed a microbial community with relatively balanced abundance, which evidenced the co-metabolism of synergetic species. The increased abundance of JGI-0000079-D21, Aminicenantales, Bacteroidetes-vadinHA17, and Mesotoga was associated with the degradation of phenols and N-heterocyclic compounds. The metabolism of acetotrophic methanogens was significantly higher than that of hydrogenotrophic methanogens in the presence of acetate. The species and abundance of functional genes were stabilized by complex components, whereas the reverse was true for single substrates. Our findings can improve the quality of the inoculants used in the biological treatments of refractory wastewater.

该文主要研究不同有机负荷发酵条件下废水的毒性作用规律,并考察三维电解技术的解毒效果.实验结果表明,随着有机负荷的升高,产甲烷活性抑制程度逐渐增强且COD去除率急剧降低,在4 g COD/L时产甲烷抑制率达到38.2％.结合高通量测序技术对发酵过程中细菌和古菌进行分析,发现微生物菌群结构发酵前后变化较为明显.而经优化的三维电解条件(电解时间90 min,电压5 V,pH=6,铁炭添加量140 g/L)对木醋液进行预处理后,4 g COD/L木醋液的甲烷产率由223.1 mL/g COD提升至344.2 mL/g COD,而抑制率降至11.2％.三维电解对于改善木醋液的可生化性及提高厌氧发酵效率有较为明显的效果.

Hydrothermal liquefaction (HTL) has shown great potential to convert sewage sludge (SS) with high moisture into bio-crude. However, the disposal and reutilization of hydrothermal liquefaction wastewater (HTLWW) is a critical issue. Anaerobic digestion (AD) is proven to be an alternative to treat organic wastewater. Therefore, energy recovery from high ash-containing SS was studied by integrating AD with HTL. The effect of temperature on HTL efficiency was investigated and then methane production from HTLWW was conducted by AD with organic loading increasing from 2 g COD/L to 6 g COD/L. Results showed that the maximum bio-crude yield of 23.5 % was obtained at 350 °C. Methane yield of 309.4 mL CH4/g CODremoved was achieved at 2 g COD/L with COD removal rate of 72.5 %. Meanwhile, the microbial structure and abundance showed great shifts resulting from the adaptation to complex compounds. JGI-000079-D21, Aminicenantales, and Bacteroidetes_ vadinHA17 predominated in the bacterial community. Due to the presence of the toxic substances in HTLWW, such as phenolic and nitrogenous heterocyclic compounds, there was a decrease in methane yield when the organic loading was higher than 4 g COD/L. The organic matters in extracellular polymeric substances (EPS) were rich in fulvic acid-like and humic acid-like substances due to the attack and stimulation of toxicants. Under the condition of unstable fermentation, Advenella and Bacillus first appeared as phenol and pyridine degrading bacteria, respectively. The microbial diversity declined sharply to demonstrate the toxic effect of the refractory organics existing at high organic loading. The enrichment of Methanosaeta in methanogens meant that acetotrophic metabolism is the dominant pathway in methanogenesis. In this study, the profile of bio-fuel production from high ash-containing SS would provide an integrated reference to treat wet biomass and recover energy simultaneously.

Methanogenic performance and microbial communities including both bacteria and archaea in UASB reactor treating acidogenic metabolites from acidification of ensiled corn stover (ECS) were investigated. Gradient organic loading rates (OLRs) were adopted to study the conversion of volatile fatty acids (VFAs) characterized by high concentration of acetic acid and propionic acid. The removal rate of chemical oxygen demand (COD) reached above 80.0 % at OLR of 8 g/L.d and volumetric methane production rate improved significantly as the OLR increased. When OLR was 10 g COD/L.d, acetic and propionic acids in effluent were accumulated and failure of methane production occurred. Compared with the control, the methanogenic inhibition was caused by the presence of high concentration of propionic acid. The profile of conversion of individual VFAs in UASB reactors was investigated at different OLRs. Furthermore, microbial communities in anaerobic sludge at OLR of 8 g COD/L.d were compared with those in inoculum and the shift of bacteria and archaea were analyzed. The abundances of some representative acetogenic bacteria such as Proteobacteria (14.18 %) and Bacteroidetes (11.16 %) increased obviously, which contributed to the oxidation and decomposition of organic acids. Acetotrophic methanogen (Methanosaeta) and hydrogenotrophic methanogen (Methanobacterium) played synergistic roles with acetogens to efficiently complete the VFAs conversion. This study will be of great importance to guide the application of two-phase AD of agricultural waste in full-scale plant.

Lignocellulosic materials (LM) are abundant bioenergy resources for renewable energy development. Pretreatment using organic acids including acetic acid (HAc) and butyric acid (HBu) was applied to reduce the recalcitrance of LM in methane production by two-phase anaerobic digestion (AD). The structural and compositional changes of solids and aqueous phase were analyzed. It showed that pretreatment with 2 g/L HAc/HBu at 120 degrees C was optimum, under which the net volatile fatty acids (VFAs) production could reach the maximum concentration of 11.5 g/L. The yield of VFAs decreased with the concentration increasing to > 2 g/L due to the feedback inhibition on the microbial metabolism. The species of organic acids also influenced the metabolic pathway of VFAs. The acidogenic metabolites can be transformed in up-flow anaerobic sludge bed (UASB) with organic loading rate (OLR) up to 12 g COD/Ld (COD, chemical oxygen demand). The hydrothermal-organic acid pretreatment (HTOAP) could provide important information for subsequent application.

Ultrasound and vacuum were respectively employed to enhance CO2 desorption in a water scrubbing biogas upgrading system. Results showed that incomplete CO2 desorption could cause a high CO2 content in the water and seriously affect the purity of the product gas. Vacuum had a strong enhancement effect on CO2 desorption. When a vacuum of 0.04 MPa was used to enhance CO2 desorption, the amount of the stripping air could be reduced to 1/16-th of that without enhancement, indicating that vacuum could greatly enhance CO2 desorption and significantly decrease the amount of the stripping air, which was expected to reduce a large amount of energy consumption. In contrast, the enhancement effect of ultrasound was not so obvious for CO2 desorption in the desorption column with air stripping, since the solution could be well desorbed by gas stripping, though ultrasound could strongly affect the static CO2 desorption.