A Novelty Strategy for AMD Prevention by Biogas Slurry: Acetate Acid Inhibition Effect on Chalcopyrite Biooxidation and Leachate.

With the widespread application of anaerobic digestion technology, biogas slurry become the main source of organic amendments in practice. Comprehensive studies into the inhibitory effects of low molecular weight (LMW) organic acids, essential components in biogas slurry, on the sulfide minerals biooxidation and its bioleaching (AMD) have been lacking. In this study, acetic acid (AA) served as a representative of LMW organic acids in biogas slurry to investigate its impact on the inhibition of chalcopyrite biooxidation by Acidithiobacillus ferrooxidans (A. ferrooxidans). It was shown that AA could slow down the chalcopyrite biooxidation and inhibit the jarosite formation on the mineral surface. Compared with the control group (0 ppm AA), the sulfate increment in the leachate of the 50 ppm, 100 ppm, and 200 ppm AA-treated groups decreased by 36.4%, 66.8%, and 69.0%, respectively. AA treatment (≥50 ppm) could reduce the oxidation of ferrous ions in the leachate by one order of magnitude. At the same time, the bacterial concentration of the leachate in the 50 ppm, 100 ppm, and 200 ppm AA-treated groups decreased by 70%, 93%, and 94%, respectively. These findings provide a scientific basis for new strategies to utilize biogas slurry for mine remediation and contribute to an enhanced comprehension of organic amendments to prevent AMD in situ in mining soil remediation.

Pharmacometrics-Enabled DOse OPtimization (PEDOOP) for seamless phase I-II trials in oncology.

We consider a dose-optimization design for a first-in-human oncology trial that aims to identify a suitable dose for late-phase drug development. The proposed approach, called the Pharmacometrics-Enabled DOse OPtimization (PEDOOP) design, incorporates observed patient-level pharmacokinetics (PK) measurements and latent pharmacodynamics (PD) information for trial decision-making and dose optimization. PEDOOP consists of two seamless phases. In phase I, patient-level time-course drug concentrations, derived PD effects, and the toxicity outcomes from patients are integrated into a statistical model to estimate the dose-toxicity response. A simple dose-finding design guides dose escalation in phase I. At the end of the phase I dose finding, a graduation rule is used to assess the safety and efficacy of all the doses and select those with promising efficacy and acceptable safety for a randomized comparison against a control arm in phase II. In phase II, patients are randomized to the selected doses based on a fixed or adaptive randomization ratio. At the end of phase II, an optimal biological dose (OBD) is selected for late-phase development. We conduct simulation studies to assess the PEDOOP design in comparison to an existing seamless design that also combines phases I and II in a single trial.

Effects of pH-varying thermal modification on sewage sludge: A focus on releasing nitrogen- and phosphorus-containing substances.

Sewage sludge is promising for the recovery and utilisation of nutrient components, but its complex nature hinders the release of these components. The combination of pH and thermal modifications shows promise for the release of nutrient components from sludge. However, comprehensive studies on the full spectrum of pH levels and corresponding mechanisms of pH-varying thermal modification are lacking. In this study, the main nutrient components, physicochemical properties, molecular structure, and noncovalent interactions of sludge were comprehensively investigated through pH-varying thermal modification (within a pH range of 2.0 to 12.0 under the same thermal condition). The experimental results showed that the release of main organics, particularly nitrogen (N)-containing organics, was well-fitted, with a tick-like function (R2: 0.74-0.96). The thermal protons exhibited a notable accumulative mutagenic effect on the N-containing organics release, while the thermal hydroxyl ions had a more direct effect, as revealed by the changes in multivalent metals and molecular structures with the protonation-deprotonation of carboxyl groups. The driving force for the release of N-containing organics was identified as the fluctuation of electrostatic interactions at the solid-liquid interface of the sludge. However, the release of phosphorus (P)-containing substances exhibited a contrasting response to that of N-containing substances with varying pH, likely because the reaction sites of thermal protons and thermal hydroxyl ions for P-containing substances were different. Moreover, high concentrations of thermal protons and hydroxyl ions collapsed the Lifshitz-van der Waals interactions of sludge, resulting in a decrease in viscoelasticity and binding strength. These propositions were further confirmed through statistical analyses of the main indicators of the main nutrient components, physicochemical properties, and noncovalent interactions of sludge. These findings can provide a basis for optimising characteristic-specific methods to recovery nutrient components (N/P) from sludge.

Pre-drying limitedly affected the yield, fuel properties, pyrolysis and combusion behavior of sewage sludge hydrochar.

While pre-drying of sewage sludge prior to hydrothermal carbonization is rarely practiced, various pre-drying methods have been performed in literature at lab-scale for convenient solid-to-liquid ratio adjustment. This has created a barrier for comparing hydrochar quality between different studies. Given pre-drying can destroy the floc structure of sewage sludge, we hypothesize that pre-drying may promote the hydrolysis step during hydrothermal carbonization process, resulting in improved hydrochar quality with low nitrogen content. In the current study, the influence of different pre-drying methods (freeze-dry, air-dry and vacuum-dry at 70 °C and 105 °C) on the subsequent hydrothermal carbonization of sewage sludge at 220 °C was assessed in terms of sewage sludge and hydrochar's chemical composition, fuel properties, pyrolysis and combustion behavior, as well as the characterization of the liquid phase. The results indicate that although pre-drying impacts sewage sludge's chemical composition, pyrolysis and combustion behavior, no significant differences exist in the yield, chemical composition, fuel properties, and pyrolysis and combustion behavior of the hydrochar. Therefore, the use of pre-drying would not affect the hydrothermal carbonization process of sewage sludge, and a comparison can be made on hydrochar quality between different studies with or without pre-drying.

Effects of production temperature on the molecular composition and seed-germination-promoting properties of sludge-based hydrochar-derived dissolved organic matter.

Sludge hydrothermal carbonization demonstrates potential for converting sludge into multifunctional carbon materials for soil remediation. However, the influence of dissolved organic matter (DOM) with unclear molecular characteristics in sludge-based hydrothermal carbon on plant growth has not been sufficiently investigated. Herein, the effects of hydrothermal temperature on the molecular transformation pathways and plant-growth-promoting properties of DOM were investigated via FT-ICR MS-based molecular network analyses and seed germination experiments. Results indicated that the highest DOM yield was achieved at 220 °C. During low-temperature (180 °C) hydrothermal treatment, the hydrolysis of biopolymers, as well as the partial condensation and cyclization of small-molecule intermediates, occurred in the sludge. This process produced unsaturated CHNO compounds containing one or two N atoms, which promoted seed germination. Further, the toxicity of DOM to plants increased with rising hydrothermal temperature. This was accompanied by S doping and aromatization reactions, which mitigated the effects of plant growth hormones. This study provides theoretical support for the optimization of sludge hydrothermal treatment and production of plant growth hormones, enhancing the ecological value of sludge-based hydrochar.

Thermal hydrolysis prior to hydrothermal carbonization resulted in high quality sludge hydrochar with low nitrogen and sulfur content.

Hydrothermal carbonization of waste activated sludge suffers from a low degree of carbonization caused by limited hydrolysis of carbohydrates and proteins, resulting in a high nitrogen content in hydrochar. Thus, it is hypothesized that thermal hydrolysis could destroy the stable floc structure of waste activated sludge, leading to higher degree of carbonization and high quality hydrochar with low nitrogen content by improving the solubilization and hydrolysis of organic matter. In the current study, thermal hydrolysis at 90 °C, 125 °C, and 155 °C was performed prior to hydrothermal carbonization to obtain low-nitrogen-content hydrochar. Thermal hydrolysis greatly improved the hydrolysis of sewage sludge. The nitrogen and sulfur content in hydrochars obtained after thermal hydrolysis decreased to 1.5-1.6 % from 1.7 %, and to 0.4 % from 0.5 %, respectively, depending on the hydrolysis conditions. Thermal decomposition stability of hydrochars obtained after thermal hydrolysis were also improved. Thermal hydrolysis at 90 °C and 125 °C promoted hydrolysis, dehydration, and the Diels-Alder reaction during hydrothermal carbonization, resulting in lower hydrochar yield but higher H/C and O/C atomic ratio. The Maillard reaction occurred during thermal hydrolysis at 155 °C, leading to the formation of large molecular refractory compounds that were retained in the hydrochar and increased the hydrochar yield. Furthermore, thermal hydrolysis can accelerate pyrolysis reaction of hydrochars, resulting in reduced energy consumption. The newly established thermal hydrolysis-hydrothermal carbonization process using sewage sludge as the feedstock has the potential to contribute to the development of the hydrothermal carbonization industry.

A 20-year shift in China's sewage sludge heavy metals and its feasibility of nutrient recovery in land use.

Recycling resources from wastewater is even more important for developing a more sustainable society. Disposing sewage sludge, which accumulates most pollutants and resources in sewage, is the main challenge in wastewater pollution control and resource utilization. Heavy metals (HMs) are the greatest constraint limiting the application of sewage sludge to land as a sustainable use of this material. We conducted a meta-analysis of the concentrations of HMs in Chinese sewage sludge by combining data from studies published from 2000 to 2019 (N = 8477). Over this period, the reported concentrations of HMs in sewage sludge declined in three stages (a fluctuating stage, a slight decrease stage, and a rapid and stable decrease stage). The results revealed that economic development and environmental policy implementation were the main factors mitigating HM pollution in sewage sludge in China. Moreover, if environmental regulations were strengthened and HM pollution-mitigation strategies were made consistent, such that the proportion of sewage sludge applied to land in China could be increased from 18.6% to 48.0% (the proportion applied to land in the United States), the ecosystem services analysis showed that huge ecological-economic benefits could be realized (3.1 billion Chinese Yuan) and the use of fertilizers could be substantially reduced (the use of nitrogen fertilizers by 8.5% and the use of phosphate fertilizers by 18.1%). This review shows that China should formulate a unified policy and interdepartmental committee for sustainable application of sewage sludge to land and wastewater resource recycling management.

Abatement of antibiotics and resistance genes during catalytic ozonation enhanced sludge dewatering process: Synchronized in volume and hazardousness reduction.

Based on the efficiency of the catalytic ozonation techniques (HDWS+O3 and MnFe2O4 @SBC+O3) in enhancing the sludge dewaterability, the effectiveness in synchronized abatement antibiotics and antibiotic resistance genes (ARGs) was conducted to determine. The results revealed that catalytic ozonation conditioning altered the distribution of target antibiotics (tetracycline (TC), oxytetracycline (OTC), norfloxacin (NOR), ofloxacin (OFL)) in the dewatered filtrate, the dewatered sludge cake and the extra-microcolony/cellular polymers (EMPS/ECPS) layers, achieving the redistribution from solid-phase adsorption to liquid-phase dissolution. The total degradation rate was over 90% for TC and OTC, 72-78% for NOR and OFL; the abatement efficiency of eleven ARGs reached 1.47-3.01 log and 1.64-3.59 log, respectively, and more than four eARGs were eliminated. The effective abatement of the absolute abundance of Mobile genetic elements (MGEs) (0.91-1.89 log) demonstrated that catalytic ozonation conditioning could also significantly inhibit horizontal gene transfer (HGT). The abundance of resistant bacteria was greatly reduced and the signal transduction of the typical ARGs host bacteria was inhibited. The highly reactive oxidation species (ROS) generated were responsible for the abatement of antibiotics and ARGs. These findings provided new insights into the sludge conditioning for ideal and synchronized reduction in volume and hazardousness by catalytic ozonation processes in sludge treatment.

Cell volume controlled by LRRC8A-formed volume-regulated anion channels fine-tunes T cell activation and function.

Biosynthesis drives the cell volume increase during T cell activation. However, the contribution of cell volume regulation in TCR signaling during T lymphoblast formation and its underlying mechanisms remain unclear. Here we show that cell volume regulation is required for optimal T cell activation. Inhibition of VRACs (volume-regulated anion channels) and deletion of leucine-rich repeat-containing protein 8A (LRRC8A) channel components impair T cell activation and function, particularly under weak TCR stimulation. Additionally, LRRC8A has distinct influences on mRNA transcriptional profiles, indicating the prominent effects of cell volume regulation for T cell functions. Moreover, cell volume regulation via LRRC8A controls T cell-mediated antiviral immunity and shapes the TCR repertoire in the thymus. Mechanistically, LRRC8A governs stringent cell volume increase via regulated volume decrease (RVD) during T cell blast formation to keep the TCR signaling molecules at an adequate density. Together, our results show a further layer of T cell activation regulation that LRRC8A functions as a cell volume controlling "valve" to facilitate T cell activation.

Biomass-Derived Carbonaceous Materials with Graphene/Graphene-Like Structures: Definition, Classification, and Environmental Applications.

Biomass-derived carbonaceous materials with graphene/graphene-like structures (BGS) have attracted tremendous attention in the field of environmental remediation. The introduction of graphene/graphene-like structures into raw biochars can effectively improve their properties, such as electrical conductivity, surface functional groups, and catalytic activity. In 2021, the International Organization for Standardization defined graphene as a "single layer of carbon atoms with each atom bound to three neighbours in a honeycomb structure". Considering this definition, several studies have incorrectly referred to BGS (e.g., biomass-derived few-layer graphene or porous graphene-like nanosheets) as "graphene". The definitions and classifications of BGS and their applications in environmental remediation have not been assessed critically thus far. Comprehensive analysis and sufficient and robust evidence are highly desired to accurately determine the specific structures of BGS. In this perspective, we provide a systematic framework to define and classify the BGS. The state-of-the-art methods currently used to determine the structural properties of BGS are scrutinized. We then discuss the design and fabrication of BGS and how their distinctive features could improve the applicability of biomass-derived carbonaceous materials, particularly in environmental remediation. The environmental applications of these BGS are highlighted, and future research opportunities and needs are identified. The fundamental insights in this perspective provide critical guidance for the further development of BGS for a wide range of environmental applications.

Electron Transfer Mechanism at the Interface of Multi-Heme Cytochromes and Metal Oxide.

Electroactive microbial cells have evolved unique extracellular electron transfer to conduct the reactions via redox outer-membrane (OM) proteins. However, the electron transfer mechanism at the interface of OM proteins and nanomaterial remains unclear. In this study, the mechanism for the electron transfer at biological/inorganic interface is investigated by integrating molecular modeling with electrochemical and spectroscopic measurements. For this purpose, a model system composed of OmcA, a typical OM protein, and the hexagonal tungsten trioxide (h-WO3 ) with good biocompatibility is selected. The interfacial electron transfer is dependent mainly on the special molecular configuration of OmcA and the microenvironment of the solvent exposed active center. Also, the apparent electron transfer rate can be tuned by site-directed mutagenesis at the axial ligand of the active center. Furthermore, the equilibrium state of the OmcA/h-WO3 systems suggests that their attachment is attributed to the limited number of residues. The electrochemical analysis of OmcA and its variants reveals that the wild type exhibits the fastest electron transfer rate, and the transient absorption spectroscopy further shows that the axial histidine plays an important role in the interfacial electron transfer process. This study provides a useful approach to promote the site-directed mutagenesis and nanomaterial design for bioelectrocatalytic applications.

Controlled One-Step Synthesis of MOF-on-MOF Cocatalysts for Two-Channel Electrocatalytic Conversion of CO2 to Formic Acid.

The synthesis of efficient and highly selective catalysts and rational reactor design play decisive roles in the industrial application of the electrocatalytic carbon dioxide reduction reaction (CO2 RR). In this study, a dual-metal-organic framework (MOF) copper-based catalytic electrode is designed and prepared in one step by in situ synthesis on a foamed copper substrate. The MOF-on-MOF structure can effectively inhibit the generation of H2 and CO, and further enhance the selectivity of HCOOH. Furthermore, by using cheap and durable poly(tetrafluoroethylene) (PTFE) instead of an expensive and fragile GDE, the optimized reactor design improves the stability and durability of the gas channel and the replaceability of the electrode. The structure-optimized reactor has a maximum Faradaic efficiency of 89.2% in neutral medium, and an average current density of 26.1 mA cm-2 in the flow cell, which has comparable performance to a GDE and can continue to operate stably. The use of PTFE improves the service life of the gas mass transfer channel, and the independent catalytic electrode can provide good catalytic efficiency. These results provide new insights into the reaction mechanism of structurally recombined double MOFs and PTFE-optimized CO2 RR reactor designs, providing technical support for the practical industrial application of the CO2 RR.

α-Aminobutyric Acid Constrains Macrophage-Associated Inflammatory Diseases through Metabolic Reprogramming and Epigenetic Modification.

Metabolites play critical roles in macrophage polarization and in their function in response to infection and inflammation. α-aminobutyric acid (AABA), a non-proteinogenic amino acid which can be generated from methionine, threonine, serine, and glycine, has not been studied extensively in relation to macrophage polarization and function. In this study, we aimed to investigate the immunomodulatory function of AABA in regulating M1 macrophage polarization and function in vitro and in vivo. We stimulated bone-marrow-derived macrophages with lipopolysaccharide (LPS) to generate M1 macrophages. Subsequently, we induced sepsis and colitis in mice, followed by treatment with AABA. We then analyzed the samples using ELISA, real-time PCR, Western blotting, flow cytometry, and histopathological analysis to evaluate cytokine secretion, inflammatory gene expression, macrophage activation, disease progression, and inflammation severity. Additionally, metabolomic and chromatin immunoprecipitation-qPCR were conducted to investigate the function of AABA on metabolic reprogramming and epigenetic modifications of M1 macrophages. Our results revealed that AABA inhibited M1 macrophage polarization and function, which led to prolonged survival in septic mice and reduced disease severity in colitis mice. Mechanically, AABA promoted oxidative phosphorylation (OXPHOS) and glutamine and arginine metabolism while inhibiting glycolysis. Moreover, AABA could increase the occupancy of trimethylation of histone H3K27 at the promoter regions of M1 macrophage-associated inflammatory genes, which contributed to the inhibition of M1 macrophage polarization. These findings suggest that AABA may have therapeutic potential for inflammatory diseases by regulating macrophage polarization and function through metabolic and epigenetic pathways.

Reconceptualization of the mechanism of thermal hydrolysis pretreatment to enhance the anaerobic conversion of sludge organic nitrogen: Decisive role of organic nitrogen occurrence.

The occurrence state of organic nitrogen (ON) is the key to affect anaerobic biotransformation of sludge. ON in sludge was chemically classified as PA (easily accessible part), PB (moderately accessible) and PC (hardly accessible) according to the modified CNCPS method. The components of them were analyzed by PY-GCMS, and it was identified that PA was extracellular amino acids, peptides and proteins; PB was genetic material, cell wall peptidoglycans and intracellular proteins; PC was ON that cross-linked with complex macromolecules. The conversion characteristics of PA, PB and PC in sludge and their relationship with anaerobic digestion (AD) performance were investigated after thermal hydrolysis pretreatment (THP) at different temperatures (100-180 °C). With the increase of THP temperature, the hydrolysis of PA and the conversion of PB to PA were promoted. At 180-THP, part of PA was converted to PC due to thermochemical reactions. In the fast degradation stage of AD of ON (ON-fast), PA is the main component of degradation; while in the slow degradation stage (ON-slow), the degradation of ON is mainly dominated by PB. Therefore, THP can significantly increase the proportion of ON-fast and reduce the ON fraction in the digestate (ON-hard). Moreover, PA and PB, rather than PC, were identified as dominant in ON-hard with or without THP for the first time, overturning the traditional view (remaining ON after AD was that cross-linked with complex macromolecules). This is due to that PA and PB are the main ON that make up microbial cells. The findings upgraded our perspective on conversion of ON of sludge during AD and inspire the shifted focus from "degrading PC" to "PC accumulation" for later use, through targeted enhanced PA degradation.

Exosomal Lnc NEAT1 from endothelial cells promote bone regeneration by regulating macrophage polarization via DDX3X/NLRP3 axis.

BACKGROUND: Bone regeneration is a complex procedure that involves an interaction between osteogenesis and inflammation. Macrophages in the microenvironment are instrumental in bone metabolism. Amount evidence have revealed that exosomes transmitting lncRNA is crucial nanocarriers for cellular interactions in various biotic procedures, especially, osteogenesis. However, the underlying mechanisms of the regulatory relationship between the exosomes and macrophages are awaiting clarification. In the present time study, we aimed to explore the roles of human umbilical vein endothelial cells (HUVECs)-derived exosomes carrying nuclear enrichment enriched transcript 1 (NEAT1) in the osteogenesis mediated by M2 polarized macrophages and elucidate the underlying mechanisms. RESULTS: We demonstrated HUVECs-derived exosomes expressing NEAT1 significantly enhanced M2 polarization and attenuated LPS-induced inflammation in vitro. Besides, the conditioned medium from macrophages induced by the exosomes indirectly facilitated the migration and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs). Mechanically, Exos carrying NEAT1 decreased remarkably both expression of dead-box helicase 3X-linked (DDX3X) and nod-like receptor protein 3 (NLRP3). The level of NLRP3 protein increased significantly after RAW264.7 cells transfected with DDX3X overexpression plasmid. Additionally, the knockdown of NEAT1 in exosomes partially counteracted the aforementioned effect of Exos. The results of air pouch rat model demonstrated that HUVECs-derived exosomes increased anti-inflammatory cytokines (IL-10) and decreased pro-inflammatory cytokines (IL-1ß and IL-6) significantly in vivo, contributing to amelioration of LPS-induced inflammation. Afterwards, we further confirmed that the HUVECs-derived exosomes encapsulated in alginate/gelatin methacrylate (GelMA) interpenetrating polymer network (IPN) hydrogels could promote the bone regeneration, facilitate the angiogenesis, increase the infiltration of M2 polarized macrophages as well as decrease NLRP3 expression in the rat calvarial defect model. CONCLUSIONS: HUVECs-derived exosomes enable transmitting NEAT1 to alleviate inflammation by inducing M2 polarization of macrophages through DDX3X/NLRP3 regulatory axis, which finally contributes to osteogenesis with the aid of alginate/GelMA IPN hydrogels in vivo. Thus, our study provides insights in bone healing with the aid of HUVECs-derived exosomes-encapsulated composite hydrogels, which exhibited potential towards the use of bone tissue engineering in the foreseeable future.

Application, mechanism and prospects of Fe-based/ Fe-biochar catalysts in heterogenous ozonation process: A review.

A growing number of novel organic contaminants have escalated the demands and challenges for water treatment technology. Advanced oxidation processes based on ozone have the advantage of strong oxidative capacity and higher efficiency, which have promising application prospects in the treatment of refractory organic contaminants. Biochar has attracted a lot of interest in recent years in wastewater treatment owing to its porous structure, portable preparation and outstanding stability. Moreover, iron species are widely used in catalytic ozonation owing to their magnetic polarization, vast abundance and low price. Despite a plethora of research on Fe-based catalysts in ozonation process, the heterogeneous catalytic ozonation with Fe-loaded biochar lacks a comprehensive compendium. This review intends to introduce the research progress on Fe-based catalysts and Fe-loaded biochar in heterogeneous catalytic ozonation progress, summarize and further explore the mechanisms and detection techniques of various active components in catalytic ozonation, as well as providing fresh insights for future research.

New strategy of drinking water sludge as conditioner to enhance waste activated sludge dewaterability: Collaborative disposal.

Drinking water sludge (DWS) and waste activated sludge (WAS) are usually treated separately. With the continuous deepening understanding of the characteristics of two types sludge, the research and application of the collaborative disposal is worth considering. The heated modification DWS (HDWS) rich in inorganic matter and aluminum (Al2O3) can be used as a conditioner to enhance WAS dewaterability using its properties with physical skeleton and chemically catalyzed ozone (O3). The results showed that the minimum values of capillary water time (CST) and specific resistance filtration (SRF) for WAS were 20.9±2.40 s and 1.07±0.19×1013 m/kg at pH=4, O3 dosage=60 mg/g VS and HDWS dosage=700 mg/g VS, corresponding to the reduction of sludge cake water content (Wc) to 60.37±0.97 %. The mechanism of HDWS+O3 enhanced WAS dewaterability was systematically elucidated through pyridine-infrared analysis and density functional theory (DFT) calculations. The surface of Al2O3 in HDWS had more Lewis acidic sites, and the oxygen atoms of O3 combined with Al atoms to form Al-O bonds and undergo electron transfer, while O3 molecules dissociated to produce more hydroxyl radicals (·OH). With the oxidation of ·OH, the extra-microcolony/cellular polymers (EMPS/ECPS) structure were destroyed and became looser, promoting the conversion of internal moisture to free moisture. Zeta potential tended to zero, particle size increased, and the surface was more hydrophobic. Correlation analysis revealed that the component content, protein (PN) secondary structure and molecular weight (MW) in ECPS were positively and more strongly correlated with the sludge dewaterability compared to EMPS. The discovery of HDWS+O3 applied to effectively enhance WAS dewaterability provided an inspiring perspective on the emerging DWS and WAS co-processing disposition.

Effect of nitrite on hydrolysis-acidification, biogas production and microbial community in semi-continuous two-phase anaerobic digestion of sewage sludge.

Previous study found that the pre-treatment of sewage sludge with nitrite improves the biogas production during the mono/two-phase anaerobic digestion (AD) using batch biochemical methane potential tests. In this study, the effects of nitrite on hydrolysis-acidification, biogas production, volatile solids destruction and microbial composition in semi-continuous two-phase AD of sewage sludge were investigated. The addition of nitrite promotes sludge organic matter solubilization (+484%) and VFAs production (+98.9%), and causes an increase in the VS degradation rate during the AD process (+8.7%). The comparison of biogas production from the acidogenic and methanogenic reactors with or without the addition of nitrite implies that the nitrite has no significant effect on the overall biogas production of two-phase sludge AD process. High-throughput sequencing analysis shows that the microbial communities of bacteria and archaea in two-phase AD reactors significantly changes after the addition of nitrite. Vulcanibacillus (bacteria) and Candidatus Methanofastidiosum (archaea) become the dominant genera in the acidogenic and methanogenic reactors with the nitrite respectively. These findings provide new insights about using nitrite to promote the organic matter degradation of sewage sludge in a semi-continuous two-phase AD system.

Effects of Preharvest Shading on Dynamic Changes in Metabolites, Gene Expression, and Enzyme Activity of Three Tea Types during Processing.

Preharvest shading significantly influences tea flavor. However, little attention has been given to the mechanism of shading on metabolites, genes, and enzymes in the processing of different tea types. Our study identified 1028 nonvolatile metabolites covering 10 subclasses using a widely targeted metabolome. The results show that shading had a greater effect on the compositions of amino acids, flavonoids, and theaflavins in tea leaves. The combined transcriptomics and enzyme activity analysis results indicate that the upregulated expression of asparagine, aspartate, and tryptophan synthesis genes and proteolytic enzymes promoted the accumulation of amino acids. The downregulated enzyme genes resulted in the reduction of nongalloylated catechins and flavonoid glycosides. Simultaneously, the accumulation of TFs in shaded tea was due to the enhanced enzymatic activities of polyphenol oxidase and peroxidase during processing. Theaflavin-3-3'-di-O-gallate was also significantly positively correlated with the antioxidant and hypoglycemic activities of shaded tea. The results contribute to a better understanding of how preharvest treatments influence summer tea quality.