Succinylated chitosan derivative restore HUVEC cells function damaged by TNF-α and high glucose in vitro and enhanced wound healing.

The inflammation of chronic wounds plays a key hindering role in the wound healing process. Slowing down the inflammatory response is significant for the repair of chronic wounds. Studies have revealed that succinate can inactivate gastrin D (GSDMD) and prevent cell pyroptosis. Chitosan has anti-inflammatory properties and is commonly used as wound healing material. Therefore, we used succinic anhydride to modify chitosan and found that N-succinylated chitosan (NSC) was more effective in inhibiting inflammation. The results showed that the stimulation of TNF-α and high glucose induces overexpression of capase-1 and TNF-α in human umbilical vein endothelial cells (HUVEC), and down-expression of CD31. However, the expression of capase-1 and TNF-α decreased, while the expression of CD31, VEGF and IL-10 was up-regulated significantly in dysfunctional HUVEC cells after treated by NSC. Moreover, NSC can speed wound healing, histological examination results showed that wounds treated with NSC exhibited faster epithelial tissue regeneration and thicker collagen deposition. Overall, this study results suggested that NSC has the function of restoring the physiological functions of dysfunctional HUVEC cells induced by high glucose and TNF-α, and can accelerate wound healing, indicating that NSC has good potential to be applied in inflammatory chronic wounds such as diabetic foot.

Effects of traditional Chinese exercises on cardiac rehabilitation in patients with myocardial infarction: a meta-analysis of randomized controlled trials.

Objective: Traditional Chinese exercises (TCE) are excellent cardiac rehabilitation (CR) training that can effectively improve cardiorespiratory fitness. However, there is no published meta-analysis of TCE on CR in patients with myocardial infarction (MI). Therefore, this study aimed to provide a comprehensive evaluation from multiple perspectives. Methods: This meta-analysis is based on the Cochrane Handbook of Systematic Reviews. Eight databases were searched from the date of database construction to March 15, 2023. Two investigators independently screened the literature and assessed their quality. The meta-analysis was performed with RevMan5.4 software. Results: A total of 21 articles involving 1,890 patients were included. N-terminal pro-brain natriuretic peptide (NT-proBNP) in the TCE group were lower than the control group (MD = -96.34, 95%CI: -140.69 ∼-51.98, P < 0.00001, I2 = 96%), the left ventricular ejection fraction (LVEF) in the TCE group was higher than the control group (MD = 4.58, 95%CI: 3.28-5.88, P < 0.00001, I2 = 79%), the left ventricular end diastolic dimension (LVDD) in TCE group was lower than the control group (MD = -3.83, 95%CI: -5.27 ∼-2.38, P < 0.00001, I2 = 94%), the left ventricular end systolic diameter (LVESD) in TCE group was lower than the control group (MD = -2.17, 95%CI: -4.10 ∼-0.24, P < 0.00001, I2 = 96%), The 6-minute walk test (6MWT) in the TCE group was higher than the control group (MD = 69.60, 95%CI: 34.59-104.60, P < 0.00001, I2 = 99%), the oxygen uptake (VO2) in the TCE group was higher than the control group (MD = 4.38, 95%CI: 2.25-6.51, P < 0.00001, I2 = 94%), the 36-item short form survey (SF-36) in the TCE group was higher than the control group (MD = 13.34, 95%CI: 9.25-17.42, P = 0.008, I2 = 75%), the Hamilton Anxiety Scale (HAMA) in the TCE group was lower than the control group (MD = -4.34, 95%CI: -5.18 ∼-3.50, P = 1.00, I2 = 0%), the Hamilton Depression Scale (HAMD) in the TCE group was lower than the control group (MD = -3.48, 95%CI: -5.35 ∼-1.61, P = 0.0002, I2 = 88%), the incidence of major adverse cardiac events (MACEs) in the TCE group was lower than the control group (RR = 0.31, 95%CI: 0.20-0.47, P = 0.52, I2 = 0%). Subgroup analysis revealed differences in TCE types could be a potential source of heterogeneity. Conclusion: MI patients who used TCE have not only notable improvements in cardiopulmonary function, physical function, quality of life, and emotions but also reduced the incidence of MACEs. Tai Chi might be more efficient than Ba Duan Jin. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023408675.

Development of a Nomogram That Predicts the Risk of Coronary Heart Disease in Patients With Hyperlipidemia.

BACKGROUND: Hyperlipidemia is one of the independent risk factors for the onset of coronary heart disease (CHD), and our aim is to construct a coronary risk prediction model for patients with hyperlipidemia based on carotid ultrasound in combination with other risk factors. METHODS: The nomogram risk prediction model is based on a retrospective study on 820 patients with hyperlipidemia. The predictive accuracy and discriminative ability of the nomogram were determined by receiver operating characteristic (ROC) curves and calibration curves. The results were validated using bootstrap resampling and a prospective study on 39 patients with hyperlipidemia accepted at consenting institutions from 2021 to 2022. RESULT: In the modeling cohort, 820 patients were included. A total of 33 variables were included in univariate logistic regression. On multivariate analysis of the modeling cohort, independent factors for survival were sex, age, hypertension, plaque score, LVEF, PLT, and HbAlc, which were all selected into the nomogram. The calibration curve for probability of survival showed good agreement between prediction by nomogram and actual observation. The area under the curve (AUC) of the nomogram model was 0.881 (95% CI 0.858∼0.905), with a sensitivity of 79% and a specificity of 81.7%. In the validation cohort, the AUC was 0.75, 95% CI (0.602∼0.906). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of this model were 54.16%, 80%, 81.25%, 52.17% and 64.1%. This model showed a good fitting and calibration and positive net benefits in decision curve analysis. CONCLUSION: A nomogram model for CHD risk in patients with hyperlipidemia was developed and validated using 7 predictors, which may have potential application value in clinical risk assessment, decision-making, and individualized treatment associated with CHD.

Effects of Buyang Huanwu Decoction on Intestinal Barrier, Intestinal Flora, and Trimethylamine Oxide in Rats with Heart Failure.

OBJECTIVE: To explore the mechanisms of Buyang Huanwu Decoction (BYHWD) modulating the gut microbiome and trimethylamine oxide (TAMO) to exert cardioprotective effects. METHODS: Ligation of the left anterior descending coronary artery was performed in rats to induce heart failure (HF). Except for the sham-operation group (n=10), 36 operation-induced models were randomized into 3 groups using a random number table (n=12 in each group): the model group, the BYHWD group (15.02 g/kg BYHWD), and the positive group (4.99 g/kg metoprolol succinate). After 4-week treatment (once daily by gavage), echocardiography was applied to evaluate the cardiac function and the Tei index (the ratio of ventricular isovolumic contraction time (IVCT) and isovolumic diastolic time (IVRT) to ejection time (ET)) was calculated; hematoxylin-eosin (HE) staining was observed to characterize the pathology of the myocardium and small intestinal villi. D-lactic acid was detected by an enzyme-linked immunosorbent assay (ELISA). Expressions of occludin, claudin-1, and zonula occludens (ZO-1) were detected by Western blot. 16S ribosomal ribonucleic acid (16S rRNA) sequencing was used to explore the changes in the intestinal flora. TMAO was detected via liquid chromatography-tandem mass spectrometry (LC-MS/MS). RESULTS: In the echocardiography, the Tei index was considerably lower in the positive and BYHWD groups compared with the model group (P<0.05). Besides, BYHWD improved the pathology of myocardium and small intestine of HF rats and lowered the D-lactic acid content in the serum, when compared with the model group (P<0.05). BYHWD also improved the expression of occludin and claudin-1 (P<0.05); in the gut microbiota analysis, BYHWD slowed down modifications in the structure distribution of gut microbiota and regulated the diversity of intestinal flora in HF rats. The content of TMAO in the serum was significantly lowered by BYWHT compared with the model group (P<0.05). CONCLUSION: BYHWD may delay progression of HF by enhancing the intestinal barrier structure, and regulating intestinal flora and TAMO.

Polyphenol-Rich Liupao Tea Extract Prevents High-Fat Diet-Induced MAFLD by Modulating the Gut Microbiota.

The modulation of gut microbiota dysbiosis might regulate the progression of metabolic-associated fatty liver disease (MAFLD). Here, we found that polyphenol-rich Liupao tea extract (PLE) prevents high-fat diet (HFD)-induced MAFLD in ApoE-/- male mice accompanied by protection of the intestinal barrier and downregulation of lipopolysaccharide (LPS)-related Toll-like receptor 4 (TLR4)-myeloid differentiation primary response 88 (MyD88) signaling in the liver. Fecal microbiome transplantation (FMT) from PLE-and-HFD-treated mice delayed MAFLD development significantly compared with FMT from HFD-treated mice. In this case, 16S rRNA gene sequencing revealed that Rikenellaceae and Odoribacter were significantly enriched and that Helicobacter was significantly decreased in not only the HFD+PLE group but also the HFD+PLE-FMT group. Furthermore, the level of 3-sulfodeoxycholic acid was significantly decreased in the HFD+PLE-FMT group compared with the HFD-FMT group. In conclusion, our data demonstrate that PLE could modulate the MAFLD phenotype in mice and that this effect is partly mediated through modulation of the gut microbiota.

Exploring biological basis of Syndrome differentiation in coronary heart disease patients with two distinct Syndromes by integrated multi-omics and network pharmacology strategy.

BACKGROUND: Traditional Chinese Medicine (TCM) is distinguished by Syndrome differentiation, which prescribes various formulae for different Syndromes of same disease. This study aims to investigate the underlying mechanism. METHODS: Using a strategy which integrated proteomics, metabolomics study for clinic samples and network pharmacology for six classic TCM formulae, we systemically explored the biological basis of TCM Syndrome differentiation for two typical Syndromes of CHD: Cold Congealing and Qi Stagnation (CCQS), and Qi Stagnation and Blood Stasis (QSBS). RESULTS: Our study revealed that CHD patients with CCQS Syndrome were characterized with alteration in pantothenate and CoA biosynthesis, while more extensively altered pathways including D-glutamine and D-glutamate metabolism; alanine, aspartate and glutamate metabolism, and glyoxylate and dicarboxylate metabolism, were present in QSBS patients. Furthermore, our results suggested that the down-expressed PON1 and ADIPOQ might be potential biomarkers for CCQS Syndrome, while the down-expressed APOE and APOA1 for QSBS Syndrome in CHD patients. In addition, network pharmacology and integrated analysis indicated possible comorbidity differences between the two Syndromes, that is, CCQS or QSBS Syndrome was strongly linked to diabetes or ischemic stroke, respectively, which is consistent with the complication disparity between the enrolled patients with two different Syndromes. These results confirmed our assumption that the molecules and biological processes regulated by the Syndrome-specific formulae could be associated with dysfunctional objects caused by the Syndrome of the disease. CONCLUSION: This study provided evidence-based strategy for exploring the biological basis of Syndrome differentiation in TCM, which sheds light on the translation of TCM theory in the practice of precision medicine.

Feasibility of reinforced post-endogenous denitrification coupling with synchronous nitritation, denitrification and phosphorus removal for high-nitrate sewage treatment using limited carbon source in municipal wastewater.

Post-endogenous denitrification (PED) process, utilizing internal rather than external carbons, has been proposed for nitrogen removal from wastewaters. However, its potential nitrogen removal capacity has not been approached, especially when facing simultaneous phosphorus removal. Here, the nitrogen removal ability of PED was further investigated by treating municipal and high-nitrate wastewaters in a novel process combined with synchronous nitritation, denitrification and phosphorus removal (SNiDPR). After optimization, the anoxic specific nitrite (and nitrate) reduction rate was increased from 0.41 to 1.13 mgN gVSS-1 h-1, accompanied with PED efficiency raising from 16.8% to 80.9%. It ensured that, by utilizing the limited organic carbons in municipal wastewater, deep-level nutrient removal could still be achieved (total nitrogen and phosphorus removal efficiencies were 93.1% and 99.9%, respectively). Nitrospira (0.1-0.4%) was outcompeted by Nitrosomonas (4.7-3.3%), which contributed to accumulation of nitrite in aerobic stage (99.6%) and dramatically reduced the carbons demand of following PED. Enriched Dechloromonas (8.5-5.6%) and Candidatus_Competibacter (9.1-11.3%) might play key roles in sufficient utilization of organic carbons in municipal wastewater anaerobically, and respectively facilitate aerobic phosphorus removal (100%) and anoxic PED (60.7% of overall nitrogen removal).

Hunzeylanines A-E, Five Bisindole Alkaloids Tethered with a Methylene Group from the Roots of Hunteria zeylanica.

Five novel bisindole alkaloids, hunzeylanines A-E (1-5), with an unprecedented skeleton were isolated from the roots of Hunteria zeylanica. Compounds 1-5 represent the first examples of akuammine-pleioarpamine-type bisindole alkaloids fused with a dihydropyran unit. Their structures including absolute configurations were established through comprehensive spectroscopic data analyses and computational calculation methods. The plausible biogenetic pathway of 1 was also proposed. Alkaloids 1 and 2 displayed moderate cytotoxicity toward three human cancer cell lines (MDA-MB-231, AV3, and Huh7).

[Stable Nitrite Accumulation and Phosphorus Removal from High-nitrate and Municipal Wastewaters in a Combined Process of Partial Denitrification and Denitrifying Phosphorus Removal (PD-DPR)].

In this study, a novel process combining partial denitrification (PD, NO3--N→NO2--N) and denitrifying phosphorus removal (DPR) in an anaerobic-anoxic-aerobic sequencing batch reactor (SBR) was developed. By comprehensively controlling the influent C/N ratio, anaerobic drainage ratio, and anoxic duration, the nitrite accumulation and phosphorus removal performance of a system treating high-strength nitrate and municipal wastewaters was investigated. The results showed that, after 140 days, the nitrate-to-nitrite transformation ratio (NTR) was 80.1%, and PO43--P removal efficiency was 97.64%. In the anaerobic stage (180 min), glycogen-accumulating organisms (GAOs) and phosphorus-accumulating organisms (PAOs) efficiently utilized the carbon source in municipal wastewater to enhance intracellular carbon storage. In the anoxic stage (150 min), denitrifying GAOs (DGAOs) and heterotrophic denitrifying bacteria (DOHOs) carried out endogenous and exogenous short-range denitrification, respectively, to achieve stable nitrite accumulation; simultaneously, denitrifying PAOs (DPAOs) carried out denitrifying phosphorus uptake to achieve efficient phosphorus removal. In the aerobic stage (10 min), without initiating ammonia/nitrite oxidation, PAOs absorbed excessive phosphorus, which improved the phosphorus removal performance of the system. The effluent NO2--N/NH4+-N of a ratio of 1.31:1 (close to the theoretical value of ANAMMOX process, 1.32:1), with little PO43--P and COD (0.30 and 12.94 mg·L-1), meets the requirements for deep-level nitrogen removal by coupling with ANAMMOX process.

Structurally Diverse Indole Alkaloids with Vasorelaxant Activity from Melodinus hemsleyanus.

Six new structurally diverse indole alkaloids, melohemsines J-M (1-4), 11-hydroxy-Δ14-vincamine (5), and 11-hydroxy-16-epi-Δ14-vincamine (6), and 15 known alkaloids were isolated from the leaves and twigs of Melodinus hemsleyanus Diels. These new compounds and their absolute configurations were determined through spectroscopic data analyses, X-ray diffraction, and computational methods. Melohemsine J (1) is the first example of a melodinus-type alkaloid possessing a 6/6/5/5/6/5 hexacyclic skeleton and containing a tetrahydrofuro[2,3-b]pyridine-2(3H)-one unit. Melohemsine K (2) is an unusual aspidosperma-type alkaloid possessing a 6/5/6/5/5 pentacyclic architecture with a contracted E ring (loss of CH2). Compounds 5-10 and 16 exhibited vasorelaxant activities with EC50 values of 0.8-3.8 µM. In addition, compound 4 displayed moderate cytotoxicity toward the tumor cell lines HepG2 and A-549 with EC50 values of 18.7 and 28.7 µM, respectively.

Hunterines A-C, Three Unusual Monoterpenoid Indole Alkaloids from Hunteria zeylanica.

Three new monoterpenoid indole alkaloids (MIAs), hunterines A-C (1-3), were isolated from Hunteria zeylanica. Compound 1 possesses a unique skeleton with an unprecedented azabicyclo[4.3.1]decane ring system. Compounds 2 and 3 are a pair of epimeric vobasinylindole alkaloid heterodimers. Their structures including absolute configurations were established by spectroscopic analyses, X-ray diffraction, computational calculation, and the modified Mosher's method. Plausible biogenetic pathways of 1-3 were also proposed. Alkaloid 1 showed moderate cytotoxic activity against the HepG2 cell line.

Two New Flavonoids from the Nuts of Areca catechu.

Two new flavonoids, calquiquelignan M (1), calquiquelignan N (2), along with nine known compounds (3-11), were isolated from the nuts of Areca catechu (Palmae). The new structures, including absolute configurations, were established by a combination of spectroscopic data and electronic circular dichroism (ECD) calculation. The known compounds were identified by comparing their spectroscopic data with reported in the literature. The flavonoids compounds (1-8) were evaluated for their cytotoxicity activities against three human cancer cell lines. Compounds 1 and 2 exhibited a moderate cytotoxic activity against HepG2 cell lines with IC50 values of 49.8 and 53.6 µM, respectively.

Achieving deep-level nutrient removal via combined denitrifying phosphorus removal and simultaneous partial nitrification-endogenous denitrification process in a single-sludge sequencing batch reactor.

The feasibility of coupling denitrifying phosphorus removal (DPR) with simultaneous partial nitrification-endogenous denitrification (SPNED) was investigated in a single-sludge sequencing batch reactor for deep-level nutrient removal from municipal and nitrate wastewaters. After 160-day operation, the DPR process simultaneously reduced most PO43--P and NO3--N anoxically, and the SPNED process achieved further total nitrogen (TN) removal at low dissolved oxygen condition with TN removal efficiency of 90.8%. The effluent NH4+-N, PO43--P and TN concentrations were 1.0, 0.1 and 7.2 mg/L, respectively. Microbial analysis revealed that Dechloromonas (6.7%) dominated DPR process, whereas the gradually enriched Nitrosomonas (4.5%) and Candidatus Competibacter (6.8%) conducted SPNED process accompanied with sharply eliminated Nitrospirae (1.4%). Based on these findings, a novel strategy was proposed to achieve further nutrient removal in conventional treatment through integrating the DPR-SPNED process. As a result, ∼100% of extra carbon and ∼10% of oxygen consumptions would be reduced with satisfactory effluent quality.

[Nitrogen and Phosphorus Removal from Low C/N Municipal Wastewater Treated by a SPNDPR System with Different Aeration and Aerobic Times].

An anaerobic (180 min)/aerobic operated sequencing batch reactor (SBR) fed with urban sewage was optimized by regulating the aeration quantity to investigate the deep-level nitrogen (N) and phosphorus (P) removal. The amount of aeration was regulated by adjusting the volume of gas per unit volume of reactor passed in unit time, when the unit is L·(min·L)-1, from 0.125 L·(min·L)-1 gradually to 0.025 L·(min·L)-1, and aerobic times from 3 h to 6 h. The experimental results show that the effluent NH4+-N, NO2--N, NO3--N, and PO43--P concentrations of the optimized SPNDPR system were 0, 8.62, 0.06, and 0.03 mg·L-1. The effluent TN concentration was about 9.22 mg·L-1, and the TN removal efficiency was up to 87.08%. When the aeration quantity was decreased from 0.125 L·(min·L)-1 to 0.100 L·(min·L)-1; then decreased to 0.075 L·(min·L)-1, the nitrification rate of the system recovered and stabilized at 0.16 mg·(L·min)-1. However, when the aeration quantity continuously decreased to 0.050 L·(min·L)-1 and then to 0.025 L·(min·L)-1, the nitrification rate decreased to 0.09 mg·(L·min)-1 and 0.06 mg·(L·min)-1. With reduction of the aeration quantity[from 0.125 L·(min·L)-1 to 0.100, 0.075, 0.050 and 0.025 L·(min·L)-1] and extension of aerobic time (from 3 h to 6 h), the TN removal efficiency increased gradually from 62.82% to 87.08%, and the SND efficiency increased from 19.57% to 72.11%. It was proven that reducing the aeration quantity can enhance the SPND function and deep denitrification by the system was realized. By enhancing the anaerobic intracellular carbon storage and aerobic phosphorus uptake, denitrifying phosphorus removal, partial nitrification, and endogenous nitrification were achieved. The SPNDPR system, after reducing aeration and prolonging aerobic time, was able to realize deep-level denitrification and dephosphorization using low C/N urban sewage.

Evaluating the potential for sustaining mainstream anammox by endogenous partial denitrification and phosphorus removal for energy-efficient wastewater treatment.

This study demonstrated a novel process configuration for sustaining mainstream anammox by integrating the anammox and endogenous partial denitrification-and-phosphorus removal (EPDPR) in two-stage sequencing batch reactors (SBRs). In the EPDPR-SBR, high nitrate-to-nitrite transformation (68.2%) and P removal (99.3%) were achieved by adjusting the anaerobic/anoxic/aerobic durations and influent nitrate concentration, providing a suitable NO2--N/NH4+-N (∼1.37) for subsequent anammox reaction. In the Anammox-SBR, ∼95% of TN was removed without external carbon and oxygen demands. Satisfactory effluent quality (∼6 mgTN/L and 0.2 mgP/L) achieved in the integrated EPDPR/anammox opens a new window towards the energy-efficient wastewater treatment. Microbial analysis further revealed that Dechloromonas (1.6-9.6%) and Candidatus Competibacter (6.4-5.8%) respectively conducted P removal and NO2--N production (79.2%) from NO3--N denitrification in the EPDPR-SBR, whereas Candidatus Kuenenia (7.0-29.7%) dominated NO2--N and NH4+-N removal (91.3% and 99.5%) in the Anammox-SBR, with 10 genera identified as denitrifying bacteria (0.6-8.1%) further reduced 18.9% of the produced NO3--N.

[Effect of the Influent C/P Ratio on the Nutrient Removal Characteristics of the SNEDPR System].

This study focuses on the nitrogen (N) and phosphorus (P) removal characteristics in a simultaneous nitrification-endogenous denitrification and phosphorus removal (SNEDPR) system at different influent C/P ratios. An extended anaerobic/low aerobic (dissolved oxygen:0.5-1.0 mg·L-1) sequencing batch reactor (SBR) fed with municipal sewage was studied by adjusting different C/P ratios (10, 15, 20, 30, and 60). The experimental results show that the proper reduction of the influent C/P ratio (C/P ratio reduced from 60 to 30) enhances the competitive advantages of phosphorus-accumulating organisms (PAOs) in the SNEDPR system. The highest phosphorus removal efficiency was achieved at a C/P ratio of 30, with the anaerobic phosphorus release rate (PRR) and aerobic phosphorus uptake rate (PUR, used as P/MLSS) reaching 3.5 mg·(g·h)-1 and 4.2 mg·(g·h)-1 respectively, and an average effluent PO43--P concentration below 0.3 mg·L-1. The percentage of PAOs contributing to the storage of endogenesis carbon (PPAO, An) reached 88.1%. However, a poor phosphorus removal performance was observed with further reduction of the influent C/P ratios to 10; both the PO43--P removal efficiency and PPAO, An decreased from 38.1% and 82.4% to 3.1% and 5.3%, respectively. The PRR and PUR were 0.2 mg·(g·h)-1 and 0.24 mg·(g·h)-1, respectively. The COD removal performance was not affected by the decreasing influent C/P ratios; the average COD removal efficiency stabilized at 85%. In addition, the nitrification performance became worse with decreasing C/P ratios (from 60 to 20) because the effluent NH4+-N and NO2--N concentrations increased from 0 and 6.9 mg·L-1 to 5.1 mg·L-1 and 16.2 mg·L-1, respectively. The nitrificaton performance recovered when the C/P ratios further decreased to 10, but the nitrite accumulation was disturbed as both the effluent NH4+-N and NO2--N concentrations reduced to 0. The effluent NO3--N concentration increased from 0.08 mg·L-1 to 14.1 mg·L-1. The SNED efficiency first decreased from 62.1% to 36.4% and then increased to 56.4%. The advantageous competition of glycogen accumulating organisms (GAOs) improved when the influent C/P ratio was lower than 15. The enhancement of the endogenous denitrification ability of GAOs might explain the recovery denitrification performance of the system when the influent C/P ratios decreased from 20 to 10.

[Effect of Different Sludge Retention Time (SRT) Operations on the Nutrient Removal Characteristics of a SNEDPR System].

This study focuses on the nitrogen (N) and phosphorus (P) removal characteristics in a simultaneous nitrification endogenous denitrification and phosphorus removal (SNEDPR) system operating at different sludge retention time (SRT). Four extended anaerobic/low aerobic (dissolved oxygen:0.5-1.0 mg·L-1)-operated sequencing batch reactors (SBRs) fed with municipal sewage were studied at different SRT of 5, 10, 15, and 25 d. The experimental results show that a shorter SRT at an SRT ≥ 10 d enhances the competitive advantage of PAOs in the system and an efficient phosphorus removal performance of the SNEDPR system was achieved at a SRT of 10 d and 15 d. Especially at an SRT of 10 d; the average PPAOs, An was 68.4%, the PRA and PUA reached 31.9 and 34.3 mg·L-1, respectively. The nitrification performance of the system was not affected by SRT changes. The most efficient nitrogen removal performance was achieved at a SRT of 15 d, with a high average TN removal and SNED efficiencies reaching 89.6% and 71.8%, respectively. At a SRT ≥ 10 d, the COD removal performance of the SNEDPR system was also not affected by SRT changes. The COD removal efficiencies were higher than 78%. However, when the SRT was shortened to 5 d, the C, N, and P performances of the system worsened due to the loss of biomass; the SNED and PO43--P removal efficiencies were as low as 5.7% and 0.5%, respectively. In addition, at an SRT=15 d, the sludge-settling performance of the system was the best. The SV and SVI were 20% and 64 mL·g-1, respectively, and the sludge concentration increased with the extension of the SRT. Under long SRT (25 d) operation, the system showed a good resistance to shock loads, but the sedimentation performance of the sludge deteriorated.

[Denitrification and Phosphorus Removal from Low C/N Urban Sewage Based on a Post-Partial Denitrification AOA-SBR Process].

This study focuses on the investigation of the nitrogen (N) and phosphorus (P) removal characteristics of a combination of enhanced phosphorus removal (EBPR) with simultaneous partial nitrification endogenous denitrification (SPND) and post-partial denitrification process. An anaerobic/aerobic/anoxic (A/O/A) operated sequencing batch reactor (SBR) fed with urban sewage was optimized by regulating the aeration rate and anoxic time. Based on this optimization, deep-level nitrogen and phosphorus removals from low C/N urban sewage could be realized. The experimental results show that the effluent PO43--P concentration decreased from 0.06 mg·L-1 to 0 mg·L-1, the effluent NH4+-N, NO2--N, and NO3--N concentrations gradually decreased from 0.18, 18.79, and 0.08 mg·L-1 to 0, 16.46, and 0.05 mg·L-1, respectively, and the TN removal efficiency increased from 72.69% to 77.97% when the aeration rate decreased from 1.0 L·min-1 to 0.6 L·min-1 and the anoxic duration was 180 min. With the reduction of the aeration rate, the SPND phenomenon became notable and the SND rate increased from 19.18% to 31.20%. When the anoxic duration was extended from 180 min to 420 min, the effluent PO43--P, NH4+-N, and NO3--N concentrations stabilized at~0, 0, and 0.03 mg·L-1, respectively. The effluent NO2--N concentration was as low as 3.06 mg·L-1, the SND rate was~32.21%, the TN removal performance gradually improved, and the TN removal efficiency was as high as 99.42%. Thus, deep-level nitrogen and phosphorus removals could be realized with the SPNDPR-PD system.

[Operating Characteristics of a DPR-SNED System Treating Low C/N Municipal Wastewater and Nitrate-containing Sewage].

In order to realize the simultaneous treatment of low C/N municipal wastewater and high nitrate wastewater, a sequencing batch reactor (SBR), inoculated with activated sludge, was used to initiate the denitrifying phosphorus removal coupled with simultaneous nitrification and endogenous denitrification (DPR-SNED). The anaerobic/anoxic/hypoxic durations and dissolved oxygen (DO) concentration were appropriately controlled, and the nitrogen and phosphorus removal characteristics were examined. The experimental results demonstrated that, in the anaerobic/hypoxia operation mode, with an anaerobic duration of 3 h and DO concentration of 0.5-1.0 mg·L-1, the simultaneous nitrification of phosphorus removal (SNEDPR) system successfully began in 60 d. The effluent PO43--P concentration was below 0.5 mg·L-1, the nutrient and COD removal efficiencies were stably maintained above 90% and 80%, respectively, and the SNED efficiency and CODins efficiency reached 70% and 95%, respectively. When the operation mode was anaerobic/anoxic/hypoxic and nitrate-containing sewage was added at the beginning of the anoxic stage, DPR-SNED was achieved with the effluent PO43--P concentration<0.5 mg·L-1, nutrient and COD removal efficiencies above 88% and 90%, respectively, and SNED efficiency and CODins efficiency maintained at 62% and 90%, respectively. After the successful initiation of DPR-SNED, enhanced intracellular carbons storage was achieved by phosphorus-and glycogen-accumulating organisms using the limited carbons in raw municipal wastewater to provide sufficient carbon sources for subsequent nutrient removal. In addition, the endogenous partial denitrification ensured the efficient nitrogen removal performance of the DPR-SNED system at low C/N conditions (average 4).

[Simultaneous Nitrogen and Phosphorus Removal Characteristics of An Anaerobic/Aerobic Operated SPNDPR System Treating Low C/N Urban Sewage].

This study focused on the nitrogen (N) and phosphorus (P) removal performance optimization of simultaneous partial nitrification-endogenous denitrification and phosphorus removal (SPNDPR) systems. An anaerobic (180 min)/aerobic operated sequencing batch reactor (SBR) fed with domestic wastewater was used for investigating the startup and optimization of SPNDPR by regulating the aeration rate and aerobic duration time. The experimental results showed that at an aerobic aeration rate of 0.8 L·min-1 and aerobic duration time of 150 min, the effluent PO43--P concentration was about 1.5 mg·L-1, with the effluent NH4+-N and NO3--N concentrations gradually decreasing from 10.28 and 8.14 mg·L-1 to 0 and 2.27 mg·L-1, respectively, and effluent NO2--N concentration increasing to 1.81 mg·L-1. When the aeration rate was increased to 1.0 L·min-1 and the aerobic duration time was shortened to 120 min, the phosphorus removal and partial nitrification-endogenous performance of the system gradually increased, but the total nitrogen (TN) removal performance initially decreased and then gradually increased. The final effluent PO43--P and NH4+-N were stably below 0.5 and 1.0 mg·L-1, respectively, aerobic nitrite accumulation and simultaneous nitrification-endogenous denitrification (SND) efficiencies were 98.65 and 44.20%, respectively, and TN removal efficiency was 79.78%. The concurrence of aerobic phosphorus absorption, denitrifying phosphorus removal, partial nitrification, and nitrification-endogenous in the aerobic stage of the SPNDPR system ensured the simultaneous removal of N and P from low C/N wastewater.