Quantitative detection of aflatoxin B1 in peanuts using Raman spectra and multivariate analysis methods.

Aflatoxin B1 (AFB1), among the identified aflatoxins, exhibits the highest content, possesses the most potent toxicity, and poses the gravest threat. It is commonly found in peanuts and their derivatives. This study employs Raman spectroscopy to monitor the AFB1 levels in moldy peanuts, providing a reliable theoretical basis for peanut storage management. Firstly, different degrees of moldy peanuts are spectrally characterized using a portable Raman spectrometer. Subsequently, a two-step hybrid strategy for feature selection is proposed, combining backward interval partial least squares (BiPLS) and variable combination population analysis (VCPA), aiming to simplify model complexity and enhance predictive accuracy. Finally, partial least squares (PLS) regression models are constructed based on different feature intervals and wavelength points. The research results reveal that the PLS regression model using the optimized feature intervals and wavelength points exhibits improved predictive capability and generalization performance. Notably, the BiPLS-VCPA-PLS model, established through the two-step optimization, selects nine wavelength variables, achieving a root mean square error of prediction (RMSEP) of 33.3147 µg∙kg-1, a correlation coefficient of the prediction set (RP) of 0.9558, and a relative percent deviation (RPD) of 3.4896. These findings demonstrate that the two-step feature optimization method, combining feature interval selection and feature wavelength selection, can more accurately identify optimal variables, thus enhancing detection efficiency and predictive precision.

In-situ methane enrichment in anaerobic digestion of food waste slurry by nano zero-valent iron: Long-term performance and microbial community succession.

In this work, nano zero-valent iron (nZVI) was added to a lab-scale continuous stirring tank reactor (CSTR) for food waste slurry treatment, and the effect of dosing rate and dosage of nZVI were attempted to be changed. The results showed that anaerobic digestion (AD) efficiency and biomethanation stability were optimum under the daily dosing and dosage of 0.48 g/gTCOD. The average daily methane (CH4) yield reached 495.38 mL/gTCOD, which was 43.65% higher than that at control stage, and the maximum CH4 content reached 95%. However, under single dosing rate conditions, high nZVI concentrations caused microbial cell rupture and loosely bound extracellular polymeric substances (LB-EPS) precipitation degradation. The daily dosing rate promoted the hydrogenotrophic methanogenesis pathway, and the activity of coenzyme F420 increased by 400.29%. The microbial analysis indicated that daily addition of nZVI could promote the growth of acid-producing bacteria (Firmicutes and Bacteroidetes) and methanogens (Methanothrix).

Determination of procymidone residues in rapeseed oil based on olfactory visualization technology.

A new means about olfactory visualization technique for the quantitative analysis of procymidone residues in rapeseed oil has been proposed. First, an olfactory visualization system was set up to collect volatile odor information from rapeseed oil samples containing different concentrations of procymidone residues. Then, we utilized four intelligent optimization algorithms, namely particle swarm optimization (PSO), genetic algorithm (GA), ant colony optimization (ACO) and simulated annealing (SA), to optimize the characteristics of the sensors. Finally, support vector machine regression (SVR) models employing optimized features were constructed for the quantitative detection of procymidone residues in rapeseed oil. The study demonstrated that the SA-SVR model demonstrated superior prediction results, achieving a high determination coefficient of prediction (RP2) at 0.9894. As indicated by the results, it is possible to successfully conduct non-destructive detection of procymidone residues in edible oil by the olfactory visualization technology.

Insight into the effect of rice-straw ash on enhancing the anaerobic digestion performance of high salinity organic wastewater.

Anaerobic digestion is an economic method for treating high salinity organic wastewater (HSOW), but performance enhancement is needed because of the inhibitory effect of high salinity. In this study, rice-straw ash (RSA) was applied to alleviate the inhibitory effect during HSOW anaerobic digestion. The results showed that, when the NaCl content increased from 0% to 3.0%, the methane production decreased by 87.35%, and the TOC removal rate decreased to 34.12%. As a K+ and alkalinity source, RSA addition enhanced the anaerobic digestion performance, and the optimal dosage was 0.88 g/L. Under this dosage, the methane production increased by 221.60%, and TOC removal rate reached 66.42% at 3.0% salinity. The addition of RSA increased the proportion of living cells in the high salinity environment, and enhanced the activity of key enzymes and electron transfer efficiency in the anaerobic digestion process. The addition of RSA with a dosage of 0.88 g/L promoted the accumulation of acetoclastic methanogen Methanothrix. The abundance of substrate transporters, ion transporters and electron transfer related functional genes were enriched, which might be key for promoting HSOW anaerobic digestion performance. The results also showed that RSA addition played an important role in maintaining the stability of the anaerobic digestion system, and it could be a potential strategy for enhancing the anaerobic digestion performance under high salinity conditions.

Individual Contributions of Amido Acid Residues Tyr122, Ile168, and Asp173 to the Activity and Substrate Specificity of Human DNA Dioxygenase ABH2.

Human Fe(II)/α-ketoglutarate-dependent dioxygenase ABH2 plays a crucial role in the direct reversal repair of nonbulky alkyl lesions in DNA nucleobases, e.g., N1-methyladenine (m1A), N3-methylcytosine (m3C), and some etheno derivatives. Moreover, ABH2 is capable of a less efficient oxidation of an epigenetic DNA mark called 5-methylcytosine (m5C), which typically is a specific target of DNA dioxygenases from the TET family. In this study, to elucidate the mechanism of the substrate specificity of ABH2, we investigated the role of several active-site amino acid residues. Functional mapping of the lesion-binding pocket was performed through the analysis of the functions of Tyr122, Ile168, and Asp173 in the damaged base recognition mechanism. Interactions of wild-type ABH2, or its mutants Y122A, I168A, or D173A, with damaged DNA containing the methylated base m1A or m3C or the epigenetic marker m5C were analyzed by molecular dynamics simulations and kinetic assays. Comparative analysis of the enzymes revealed an effect of the substitutions on DNA binding and on catalytic activity. Obtained data clearly demonstrate the effect of the tested amino acid residues on the catalytic activity of the enzymes rather than the DNA-binding ability. Taken together, these data shed light on the molecular and kinetic consequences of the substitution of active-site residues for the mechanism of the substrate recognition.

A novel regulator in cancer initiation and progression: long noncoding RNA SHNG9

Cancer has become the most common life-threatening disease in the world. Cancers presenting with advanced stages and metastasis show poor prognosis, even with the application of radiotherapy, surgery, chemotherapy and immunotherapy. It is of great importance to explore novel, efficient biomarkers and their internal mechanisms. Recently, it has been reported that long noncoding RNAs (lncRNAs) play important roles in tumor initiation and progression, influencing downstream mRNAs by interacting with miRNAs and functioning as sponges in competing endogenous RNA (ceRNA) networks. Small nucleolar RNA host gene 9 (SNHG9) binds with miRNAs, inducing miRNA downregulation. The downregulated miRNAs enhance downstream target gene expression via ceRNA networks. Dysregulation of SNHG9 is widely observed in tumors and is associated with clinical prognosis features, which makes it a valuable target for cancer biomarkers and therapeutics. Dysregulated SNHG9 in tumor cells also functions in tumor proliferation, colony formation, migration, invasion and inhibition of apoptosis and tumor cell metabolism. This systematic review of SNHG9 in tumors provides new perspectives on cancer diagnosis and treatment (AU)

Enhancement of methane production in anaerobic digestion of high salinity organic wastewater: The synergistic effect of nano-magnetite and potassium ions.

During high salinity organic wastewater (HSOW) anaerobic digestion treatment, the process of methanogenesis can be severely inhibited in the high salinity environment, and the accumulation of volatile organic acids (VFAs) leads to failure of the anaerobic reaction. In this study, nano-magnetite and KCl were adopted to alleviate the inhibitory effect of high salinity and enhance the HSOW anaerobic digestion performance. The result showed that, under the optimal dosage of 200 mg/L, nano-magnetite addition promoted the anaerobic digestion performance, and the methane production increased by 11.06%. When KCl was added with a dosage of 0.174%, the methane production increased by 98.37%. The simultaneous addition of nano-magnetite (200 mg/L) and KCl showed a synergistic effect on enhancing HSOW anaerobic digestion performance, and the methane production increased by 124.85%. The addition of nano-magnetite and KCl promoted the conversion of VFAs, especially accelerated the degradation of propionic acid and butyric acid, also it promoted the activity of acetate kinase, dehydrogenase and F420, and thereby enhanced the methanogenesis process. This study could provide a new method for enhancing the anaerobic digestion of HSOW.

Food waste digestate composting enhancement by sodium polyacrylate addition: Effects on nitrogen transformation processes and bacterial community dynamics.

The influences of sodium polyacrylate (PAAS) at the ratios of 0% (CK), 0.5% (F1), 1.0% (F2), 1.5% (F3), 2.0% (F4) and 2.5% (F5) on nitrogen transformation and bacterial community composition were investigated in the composting of food waste digestate (FWD) and corn straw (CS). PAAS addition increased the thermophilic temperature but had no significant effect on pH values. PAAS exerted significantly effects on the concentration of total nitrogen (TN), ammonia nitrogen (NH4+-N), nitrite-nitrogen (NO2--N) and nitrate-nitrogen (NO3--N). The compost product in 1.0% PAAS treatment was more active in absorbing nutrients. Firmicutes (9.40-83.54%), Actinobacteriota (9.98-51.50%), Proteobacteria (0.20-27.87%) and Bacteroidota (0.11-34.69%) were the dominant phyla in FWD composting. Moreover, relative to CK, PAAS promoted the propagation of dominant bacterial phyla Firmicutes with increment of 30.05-102.06% in the thermophilic phase. Kroppenstedtia, Thermobifida and Saccharomonospora were observed to be dominant at the maturing phase and correlated with NH4+-N, NO2--N, TN and NO3--N. Therefore, they might be regarded as probable biomarkers symbolic for the maturing phase during FWD composting. The compost product had the highest maturity degree in 1.0% PAAS treatment. These results indicated that PAAS addition improved the maturity and nutrient contents of the compost product as well as altered compost bacterial community dynamics.

A novel regulator in cancer initiation and progression: long noncoding RNA SHNG9.

Cancer has become the most common life-threatening disease in the world. Cancers presenting with advanced stages and metastasis show poor prognosis, even with the application of radiotherapy, surgery, chemotherapy and immunotherapy. It is of great importance to explore novel, efficient biomarkers and their internal mechanisms. Recently, it has been reported that long noncoding RNAs (lncRNAs) play important roles in tumor initiation and progression, influencing downstream mRNAs by interacting with miRNAs and functioning as sponges in competing endogenous RNA (ceRNA) networks. Small nucleolar RNA host gene 9 (SNHG9) binds with miRNAs, inducing miRNA downregulation. The downregulated miRNAs enhance downstream target gene expression via ceRNA networks. Dysregulation of SNHG9 is widely observed in tumors and is associated with clinical prognosis features, which makes it a valuable target for cancer biomarkers and therapeutics. Dysregulated SNHG9 in tumor cells also functions in tumor proliferation, colony formation, migration, invasion and inhibition of apoptosis and tumor cell metabolism. This systematic review of SNHG9 in tumors provides new perspectives on cancer diagnosis and treatment.

Enhanced chloride-free snow-melting agent generation from organic wastewater by integrating bioconversion and synthesis.

In this study, a new process for producing chloride-free snow-melting agents (CSAs) was proposed. Organic wastewater was converted to total volatile fatty acids (TVFA) by anaerobic acidogenic fermentation. The experiments for acid generation showed that the maximum TVFA concentration of 45.9 g/L was obtained at an organic loading rate of 5 g chemical oxygen demand /(L·d), and the proportion of acetic acid reached 78.8 %. Forward osmosis was used for concentrating the TVFA solution. The obtained CSAs, after evaporation and crystallization, had a better ice-melting capacity and less corrosion on metal and concrete than NaCl and CaCl2. Additionally, the damage caused by CSAs to the germination of plant seeds was significantly lesser than that caused by chloride salts. This study proposed a feasible method for the high-value conversion of organic wastewater, providing a new direction for the reuse of organic wastewater.

Preparation, Characterization, and Photocatalytic Performance of Ag/BiOBr0.85I0.15 Nanocomposites.

In the present paper, a series of Ag/BiOBr0.85I0.15 composite nanoparticles with different silver loading were prepared by a combined solvothermal and photocatalytic reduction method. The composite samples have been characterized by XRD, XPS, SEM, EDX, TEM, UV-Vis, and N2 adsorption/desorption techniques. The characterization results showed that BiOBr0.85I0.15 composite nanoparticles have a tetragonal phase structure. Silver nanoparticles are uniformly distributed on the BiOBr0.85I0.15, which results in surface plasmon resonance absorption, effectively increasing the visible light absorption ability of BiOBr0.85I0.15. The photocatalytic activity of the samples was evaluated by photocatalytic degradation of ammonia nitrogen in circulating aquaculture water under simulated sunlight irradiation. The effect of the Ag loading amount on the photocatalytic degradation of ammonia nitrogen was investigated. Silver loading of 1% (molar ratio) can effectively improve the degradation capacity of the catalyst for ammonia nitrogen in water. The recycling experiments show that 1%Ag/BiOBr0.85I0.15 has good photocatalytic stability. ESR characterization and oxidation species scavenging experimental results suggest that h+, 1O2, and ·O2- are the main oxidizing species in the photocatalytic system.

Leptin mediates the suppressive effect of partial fat removal on cellular and humoral immunity in striped hamsters.

Leptin secreted mainly by white adipose tissues (WAT) plays an important role in immune responses. To understand the role of energy status and leptin in immunity, bilateral perigonadal fat pads were removed or sham-removed in male striped hamsters (Cricetulus barabensis). Half of these hamsters were injected with sterile saline, and another half were administrated with exogenous leptin each day, which lasted for 20 days. Fat removal reduced total body fat mass and leptin titers significantly, leptin administration increased leptin levels in the fat removed hamsters to the control levels, but did not affect total body fat mass. Body mass and gross energy intake were not affected by fat removal, leptin supplement or their interaction. Fat removal decreased thymus mass, phytohaemagglutinin (PHA) response at 12 h, and the levels of immunoglobin (Ig) G 5, IgG10, IgM5, IgM10, IL-2, IL-4, and TNF-α, indicating a reduction in fat mass suppressed cellular and humoral immunity and the production of cytokines. However, fat removal had no effect on spleen mass, bacteria killing activity and IFN-γ titers. Leptin supplement increased PHA response at 6 h and 12 h, and the levels of IgG5, IgG10, IL-4, and IFN-γ to the control levels, implying its boosting effects on these parameters. In addition, leptin level was positively correlated with body fat mass, PHA 6 h, 12 h, Ig G10, Ig M5, Ig M10, IL-2, IL-4, and TNF-α. Collectively, these findings implied leptin was a link between energy status and immunity, and leptin mediated the suppressive effects of reduced energy storage on cellular and humoral immunity.

Coagulation removal of dissolved organic matter (DOM) in nanofiltration concentrate of biologically treated landfill leachate by ZrCl4: Performance, mechanism and coagulant recycling.

Coagulation treatment is often applied for removing the residual refractory dissolved organic matter (DOM) in biologically treated landfill leachate nanofiltration concentrate (LLNC) before discharge or further desalination treatment. However, the DOM removal efficiency by traditional coagulant needs to be improved, and two problems including the coagulant loss and difficulty in disposal of coagulation sludge need to be resolved. Based on this practical demand, a new coagulant ZrCl4 was adopted for LLNC treatment for the first time. The results showed that, ZrCl4 was better than the traditional coagulants (FeCl3 and AlCl3) for DOM removal. Under the optimal condition of pH 6.0 and ZrCl4 dosage of 5.0 mM, the DOC content, UV254 and chromaticity of the LLNC reduced by 73.32%, 83.17% and 93.59%, respectively. All of the coagulants tested in this study could efficiently remove the hydrophobic and high molecular organics. There was an obvious difference between them for removal of hydrophobic, and small or medium molecular organics, and ZrCl4 was more effective. This might be due to the stronger negative charge neutralization capacity and larger floc size of ZrCl4, which was beneficial for DOM combination and adsorption. The loss of zirconium was only 2.11%, which was much lower than that of iron and aluminum. Furthermore, being recycled for 3 times after coagulant regeneration, the recovered zirconium coagulant showed no obvious difference with the original ZrCl4 for DOM removal, indicating the disposal problem of the produced coagulation sludge can be resolved. This study could provide a promising method for LLNC treatment.

A Novel m1A-Score Model Correlated With the Immune Microenvironment Predicts Prognosis in Hepatocellular Carcinoma.

RNA methylation plays crucial roles in gene expression and has been indicated to be involved in tumorigenesis, while it is still unclear whether m1A modifications have potential roles in the prognosis of hepatocellular carcinoma (HCC). In this study, we comprehensively analyzed RNA sequencing (RNA-seq) data and clinical information using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases. We collected 10 m1A regulators and performed consensus clustering to determine m1A modification patterns in HCC. The CIBERSORT method was utilized to evaluate the level of immune cell infiltration. Principal component analysis was used to construct the m1A-score model. In the TCGA-LIHC cohort, the expression of all 10 m1A regulators was higher in tumor tissues than in normal control tissues, and 8 of 10 genes were closely related to the prognosis of HCC patients. Two distinct m1A methylation modification patterns (Clusters C1 and C2) were identified by the 10 regulators and were associated with different overall survival, TNM stage and tumor microenvironment (TME) characteristics. Based on the differentially expressed genes (DEGs) between C1 and C2, we identified three gene clusters (Clusters A, B and C). C1 with a better prognosis was mainly distributed in Cluster C, while Cluster A contained the fewest samples of C1. An m1A-score model was constructed using five m1A regulators related to prognosis. Patients with higher m1A scores showed a poorer prognosis than those with lower scores in the TCGA-LIHC and GSE14520 datasets. In conclusions, our study showed the vital role of m1A modification in the TME and progression of HCC. Quantitative evaluation of the m1A modification patterns of individual patients facilitates the development of more effective biomarkers for predicting the prognosis of patients with HCC.

Preparation of spiramycin fermentation residue derived biochar for effective adsorption of spiramycin from wastewater.

Spiramycin (SPI) fermentation residue (SFR) is classified as hazardous waste in China because of the residual antibiotics in it. SFR disposal in the traditional way is costly and wasteful of resources. In this study, pyrolysis method was adopted to covert SFR to biochar for SPI removal from wastewater, and the SPI adsorption performance was investigated. The results showed that the optimal pyrolysis temperature was 700 °C as the prepared biochar BC700 exhibited the highest SPI removal efficiency. The specific surface area of BC700 was 451.68 m2/g, and the maximum adsorption capacity was 147.28 mg/g. The adsorption mechanism involved electrostatic interaction, pore filling, π-π interaction, hydrogen bonding, and the participation of C-C and O-CO functional groups in the adsorption. No residual SPI was detected in BC700 indicating the detoxification of SFR was achieved. Moreover, after recycling for 5 times, the SPI removal efficiency was still higher than 80.0%. Therefore, this study could provide a promising method for SFR disposal.

Enhanced biogas biological upgrading from kitchen wastewater by in-situ hydrogen supply through nano zero-valent iron corrosion.

The in-situ hydrogen supply by nano zero-valent iron (nZVI, nFe0) corrosion provided a feasible way to improve the efficiency of biogas biological upgrading. This work studied the effects of nZVI at different dosages (0, 2, 4, 6, 8 and 10 g/L) on anaerobic digestion of kitchen wastewater by two buffer systems 2-[4-(2-hydroxyethyl) piperazin-1-yl] ethanesulfonic acid (HEPES) and sodium hydrogen carbonate (NaHCO3). The addition of nZVI improved the content of methane (CH4) and stability of anaerobic digestion process. In HEPES buffer system, the CH4 was all increased and the maximum reached 90.51% with 10 g/L nZVI, higher than 32.25% compared to the control. The maximum hydrogen enrichment (HE) was 113 ppb after nZVI addition, indicating the mass transfer efficiency of hydrogen (H2) was improved. Microbial community analysis showed that the total relative abundance of Methanobacterium and Methanolinea at 10 g/L nZVI was 53.72%, which was 1.62 times of the control group. However, in the NaHCO3 buffer system with 10 g/L nZVI addition, the content of CH4 and the loosely bound extracellular polymeric substances (LB-EPS) was lower than the control. The results indicated that the addition of nZVI was feasible for biogas upgrading, and the bidirectional effect of nZVI on the promotion or inhibition of bio-methanation might be related to the buffer system of the anaerobic process.

Linkage of community composition and function over short response time in anaerobic digestion systems with food fermentation wastewater.

We investigated the short-term dynamics of microbial composition and function in bioreactors with inocula collected from full-scale and laboratory-based anaerobic digestion (AD) systems. The Bray-Curtis dissimilarity of both inocula was approximately 10% of the predicted Kyoto Encyclopedia of Genes and Genomes pathway and 40% of the taxonomic composition and yet resulted in a similar performance in methane production, implying that the variation of community composition may be decoupled from performance. However, the significant correlation of volatile fatty acids with taxonomic variation suggested that the pathways of AD could be different because of the varying genus. The predicted function of the significantly varying genus was mostly related to fermentation, which strengthened the conclusion that most microbial variation occurred within the fermentative species and led to alternative routes to result in similar methane production in methanogenic bioreactors. This finding sheds some light on the understanding of AD community regulation, which depends on the aims to recover intermediates or methane.

Formononetin protects against ox-LDL-induced endothelial dysfunction by activating PPAR-γ signaling based on network pharmacology and experimental validation.

Formononetin (FMNT), a flavonoid identified from the Chinese herb Astragalus membranaceus, possesses anti-inflammatory or anti-oxidative properties in different human diseases. This study aims to comprehensively elucidate the function of FMNT in atherosclerosis and its underlying mechanisms. Online public databases were used to identify the drug-disease targets. Protein-protein interaction (PPI), Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment were applied to explore the potential targets and signaling pathways involved in FMNT against atherosclerosis. Human umbilical vein endothelial cells (HUVECs) were exposed to oxidized low-density lipoprotein (ox-LDL) to construct an atherosclerosis cell model in vitro. Endothelial cell function was assessed via examining cell proliferation, inflammatory factors, oxidative markers, reactive oxygen species (ROS), and apoptosis. Western blot was performed to detect the expression of cyclooxygenase-2 (COX-2), endothelial nitric oxide synthase (eNOS), cleaved caspase-3, and peroxisome proliferator-activated receptor-γ (PPAR-γ). A total of 39 overlapping target genes of FMNT and atherosclerosis were identified. Through the PPI network analysis, 14 hub genes were screened and found to be closely relevant to inflammation, oxidative stress, and apoptosis. Results of KEGG pathway assays indicated that lots of targets were enriched in PPAR signaling. Functionally, FMNT could protect against ox-LDL-induced inflammatory reaction, oxidative stress, and apoptosis in HUVECs. Moreover, FMNT attenuated ox-LDL-mediated inactivation of PPAR-γ signaling. GW9662, a PPAR-γ antagonist, reversed the inhibitory effect of FMNT on ox-LDL-induced endothelial injury. In conclusion, FMNT alleviates ox-LDL-induced endothelial injury in HUVECs by stimulating PPAR-γ signaling, providing a theoretical basis for employing FMNT as a potential drug to combat atherosclerosis.Abbreviations: FMNT: formononetin; PPI: protein-protein interaction; GO: Gene Ontology; KEGG: Kyoto Encyclopedia of Genes and Genomes; HUVECs: human umbilical vein endothelial cells; ox-LDL: oxidized low-density lipoprotein; COX-2: cyclooxygenase-2; eNOS: endothelial nitric oxide synthase; PPAR-γ: peroxisome proliferator-activated receptor-γ; CVD: cardiovascular disease; TCM: traditional Chinese medicines; OGDR: oxygen-glucose deprivation/reoxygenation; ROS: reactive oxygen species; FBS: fetal bovine serum; CCK-8: cell counting kit-8; EdU: 5-Ethynyl-2'-deoxyuridine; SOD: antioxidant enzymes superoxide dismutase; MDA: malondialdehyde; DCFH-DA: 2',7'-dichlorofluorescein-diacetate; PVDF: polyvinylidene fluoride; ANOVA: one-way analysis of variance; PPARs: peroxisome proliferation-activated receptors.

Characterization of algal organic matter as precursors for carbonaceous and nitrogenous disinfection byproducts formation: Comparison with natural organic matter.

Algal organic matter (AOM) and natural organic matter (NOM) from a typical eutrophic lake were comprehensively investigated in terms of their physico-chemical property, components and disinfection byproduct formation potentials (DBPFPs). The relationships between specific chemical properties of AOM and NOM with their corresponding DBPFPs were further evaluated during chlorination. Results indicated that AOM had lower specific UV absorbance (SUVA) but richer organic nitrogen contents than NOM. Fluorescence excitation emission matrix spectroscopy further demonstrated that AOM were chiefly composed of aromatic protein-like and soluble microbial byproduct-like matters, while NOM were mainly contributed from humic acid-like and soluble microbial byproduct-like substances. Although the molecular weight (MW) distribution of AOM and NOM showed no significant difference, size-exclusion chromatography with organic carbon as well as organic nitrogen detection (LC-OCD-OND) revealed that AOM were concentrated with the fraction of building blocks and NOM had higher concentrations of biopolymers and humics (HS). Moreover, AOM displayed higher DBPFPs than NOM, especially for nitrogenous DBPFP (N-DBPFP). MW < 1 kDa fractions both in AOM and NOM contributed the largest proportion to the formation of carbonaceous disinfection byproducts (C-DBPs). In addition, Pearson correlation analysis showed that bulk parameter SUVA was significantly relevant to the formation potentials of trihalomethane both in AOM and NOM, but was ineffective for carbonaceous DBPFP (C-DBPFP) prediction. Dissolved organic nitrogen contents in biopolymer and HS characterized by LC-OCD-OND had strong correlations with N-DBPFPs from AOM and NOM, indicating that LC-OCD-OND quantitative analysis could improve the prediction accuracy of the DBP formation than bulk parameters during NOM and AOM chlorination.

Synergetic enhancement of methane production and system resilience during anaerobic digestion of food waste in ammonia-tolerant anaerobic sludge system.

The anaerobic digestion (AD) of food waste (FW) was augmented with ammonia-tolerant anaerobic sludge (ATAS). Different inoculum substrate ratios (ISR) under an initial ammonia stress of 4220 mg N/L were investigated. Results showed that the average specific methane production (SMP) of FW in the ATAS system increased by 36% compared with that in un-acclimated anaerobic sludge. SMP with ISR of 1:2.5 increased by approximately 6 times. Volatile fatty acids (VFAs) accumulation and sharp pH decline were not detected. These results revealed the high performance of ATAS in simultaneously relieving ammonia and acid stress. This improvement was attributed to multiple factors. ATAS had high ammonia tolerance and ability in conversion of acetate into methane. The equilibrium of NH3/NH4+, CO2/H2CO3/HCO3-, and CxHyCOOH/CxHyCOO- could promote VFAs and ammonia ionization, reduce the levels of free VFAs and ammonia, neutralize pH, and thus enhance the system's buffering capacity to be less susceptible to fluctuations. These results demonstrated that employing ATAS in improving AD performance and resilience from acid and ammonia inhibition is feasible and effective.