Augmentation of hepatocellular carcinoma malignancy by annexin A5 through modulation of invasion and angiogenesis.

BACKGROUND: Hepatocellular carcinoma (HCC) continues to play a substantial role in cancer-related morbidity and mortality, largely owing to its pronounced tumor heterogeneity and propensity for recurrence. This underscores the pressing need for in-depth examination of its highly malignant mechanisms. Annexin A5 (ANXA5), recognized as a hallmark tumor protein, has emerged as a focal point of interest because of its ambiguous function and mechanism in HCC prognosis. This study aimed to provide a comprehensive understanding of the role of ANXA5 in the malignant progression of human HCC cells by employing an integrative approach that combines conventional experimental methods with RNA sequencing. METHODS: Differences in ANXA5 expression between HCC tissues and corresponding nontumor tissues were evaluated using immunofluorescence (n = 25). Correlation analysis was subsequently performed to assess the association between ANXA5 expression and clinicopathological features (n = 65). The role of ANXA5 in human HCC cell lines with ANXA5 gene knockout and overexpression was explored in vitro using migration and invasion assays and Ki-67 indices and in vivo based on node mice xenograft model. A tube formation assay using human umbilical vein endothelial cells (HUVECs) was conducted to demonstrate the angiogenic effects of ANXA5 in HCC. Single-cell and bulk RNA sequencing was used to further investigate the underlying mechanisms involved. RESULTS: This study revealed that ANXA5 is highly expressed in patients with HCC and correlates with poor prognosis. Assays for migration, invasion, and proliferation based on ANXA5 gene knockout and overexpression systems in human HCC cell lines have demonstrated that ANXA5 enhances HCC malignancy in vitro and in vivo. Tube formation assays of HUVECs indicated that ANXA5 facilitates angiogenesis and recruits endothelial cells to HCC cells. Single-cell and bulk RNA sequencing data analysis further confirmed that ANXA5 expression in HCC is associated with hepatocyte metabolism, immune response activation, and various oncogenic signaling pathways. CONCLUSIONS: This study revealed a meaningful association between elevated ANXA5 expression in tumor tissues and an unfavorable prognosis in patients with HCC. In addition, ANXA5 promotes HCC malignancy by promoting invasion and angiogenesis. Thus, ANXA5 has emerged as a promising therapeutic target for HCC and has the potential to improve patient outcomes.

Optimized pre-treatment of high strength food waste digestate by high content aluminum-nanocluster based magnetic coagulation.

Coagulation-based pre-treatment efficiency of high strength digestate of food waste (HSDFW) anaerobic digestion is negated by organic ligand-catalyzed decomposition of coagulants. In this study, an efficient HSDFW pre-treatment method, magnetic seeds (MS) coagulation, was employed by using highly stable Keggin Al30 nanocluster (PAC30), MS and polyacrylamide (PAM), and its operation was optimized by evaluating the performance of removing turbidity, total suspended solids (TSS), chemical oxygen demand (COD), and total phosphorous (TP) phosphate. Results showed that at the optimum dosage of 4.82 g/L, PAC30 demonstrated excellent removals as high as 98.93% ± 0.1% of turbidity, 98.04% ± 0.1% of TSS, 58.28% ± 0.3% of total COD, 99.98% ± 0.01% of TP and 99.50% ± 0.01% of dissolved phosphate, respectively. Apparent molecular weight (AMW) and three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectroscopy analyses demonstrated more efficient removal of dissolved organic matter (DOM), particularly non-biodegradable and hydrophobic components by PAC30 than commercial coagulant. The sedimentation was much improved from 40 min by coagulation/flocculation to about 5 min settling by MS coagulation. The PAC30 based magnetic coagulation (MC) presents theoretical guidance on a cost-effective and much less footprint pre-treatment alternative for high strength wastewater.

Optimizing City-Scale Demolition Waste Supply Chain Under Different Carbon Policies.

In order to establish a green, low-carbon circular development economic system, imperative goals include achieving carbon peaking and carbon neutrality. This research delves into the resource utilization of city-scale demolition waste (C&DW), aligning with environmental protection needs and sustainable development principles. The paper introduces a unique closed-loop supply chain (CLSC) model tailored for C&DW and employs a distinctive mixed integer nonlinear programming (MINLP) model for optimization. Guangzhou serves as a case study for thorough analysis, verification, and practical application of the proposed model, especially under diverse scenarios of carbon price (CP) and carbon trading (CT) policies. The key conclusions drawn from this study include the following: (1) The cost of carbon emissions is intricately influenced by both carbon emissions and carbon price, with the latter effectively regulating the carbon emissions during C&DW recycling. (2) The implementation of a CT policy, with a fixed carbon price, contributes to a further reduction in the cost of C&DW recycling treatment. (3) Under equivalent conditions, the CT policy demonstrates the potential to decrease costs and enhance the economic benefits within the building environmental protection product market. The research outcomes not only contribute to the advancement of management theory in the C&DW recycling supply chain (SC) but also provide a robust theoretical foundation for governmental initiatives aimed at introducing effective C&DW recycling management policies.

Analysis and prediction of the efficacy and influencing factors of camrelizumab combined with TACE and sorafenib in the treatment of advanced hepatocellular carcinoma.

BACKGROUND: TACE combined with targeted therapy is a method for the treatment of hepatocellular carcinoma. After adding camrelizumab, some patients had gained benefits, but some patients have produced serious adverse reactions. Therefore, more studies are needed to prove the efficacy and adverse reactions, and prediction models are needed to help with decision-making. METHODS: With ethics committee approval, a bi-center retrospective study was finished. A total of 235 patients were enrolled and divided into the treatment group of camrelizumab combined with TACE and sorafenib and the treatment group of TACE and sorafenib. The survival rate, short-term efficacy and adverse reactions were compared, and the efficacy prediction model was established. RESULTS: The 2-year survival time and objective response rate of the treatment group of camrelizumab combined with TACE plus sorafenib were higher than those of TACE plus sorafenib. Camrelizumab increased the proportion of reactive capillary proliferation, but had no effect on other adverse reactions. The established nomogram can accurately predict the response to the treatment. CONCLUSIONS: Camrelizumab combined with TACE and sorafenib can improve the survival rate of patients with hepatocellular carcinoma, and it is an effective treatment. The nomogram model can predict the efficacy, which is beneficial for patients.

Deep-Learning-Assisted Underwater 3D Tactile Tensegrity.

The growth of underwater robotic applications in ocean exploration and research has created an urgent need for effective tactile sensing. Here, we propose an underwater 3-dimensional tactile tensegrity (U3DTT) based on soft self-powered triboelectric nanogenerators and deep-learning-assisted data analytics. This device can measure and distinguish the magnitude, location, and orientation of perturbations in real time from both flow field and interaction with obstacles and provide collision protection for underwater vehicles operation. It is enabled by the structure that mimics terrestrial animals' musculoskeletal systems composed of both stiff bones and stretchable muscles. Moreover, when successfully integrated with underwater vehicles, the U3DTT shows advantages of multiple degrees of freedom in its shape modes, an ultrahigh sensitivity, and fast response times with a low cost and conformability. The real-time 3-dimensional pose of the U3DTT has been predicted with an average root-mean-square error of 0.76 in a water pool, indicating that this developed U3DTT is a promising technology in vehicles with tactile feedback.

Enhanced thermal, safety and anti-hygroscopicity performance of core-shell ammonium perchlorate with a double coating layer.

A new core-shell structure AP/Cu-DABT/Cu(Pa)2 (10 wt% each) (AP = ammonium perchlorate, DABT = 3,3'-diamino-5,5'-bis(1H-1,2,4-triazole), Pa = palmitic acid) with two coating layers was synthesized through two self-assembly reactions to improve the thermal decomposition performance, safety performance and moisture absorption resistance of AP. The results show that the surface of AP particles is uniformly and densely covered by Cu-DABT and Cu(Pa)2 coatings successively. Compared with pure AP, the HTD (high-temperature decomposition) peak temperature and activation energy of the AP/Cu-DABT/Cu(Pa)2 (10 wt% each) composite material were reduced by 74.7 °C and 117.67 kJ mol-1, respectively, and the heat release increased by 1421.02 J g-1. In addition, the burning rate and maximum flame temperature of the propellant containing the AP/Cu-DABT/Cu(Pa)2 (10 wt% each) composite were increased by 8.7 mm s-1 and 815.8 °C, respectively, compared with the propellant containing pure AP. Moreover, compared with pure AP, the contact angle of the AP/Cu-DABT/Cu(Pa)2 (10 wt% each) composite with water increased by 89.15°, and the water content decreased by 0.38 wt%. The impact sensitivity and friction sensitivity of the composite material were reduced by 16.9 cm and 96%, respectively. Analysis shows that the Cu-DABT coating plays a major role in improving the thermal properties of the composite material, the burning rate and flame temperature of the propellant, while the Cu(Pa)2 coating plays a major role in improving the hygroscopic performance and safety performance of the composite material. The composite material has good thermal decomposition properties, anti-hygroscopic properties and safety properties, so the composite material is very promising as a potential additive for solid propellants.

Determination of key events in mouse hepatocyte maturation at the single-cell level.

Hepatocytes, the liver's predominant cells, perform numerous essential biological functions. However, crucial events and regulators during hepatocyte maturation require in-depth investigation. In this study, we performed single-cell RNA sequencing (scRNA-seq) and single-nucleus RNA sequencing (snRNA-seq) to explore the precise hepatocyte development process in mice. We defined three maturation stages of postnatal hepatocytes, each of which establishes specific metabolic functions and exhibits distinct proliferation rates. Hepatic zonation is gradually formed during hepatocyte maturation. Hepatocytes or their nuclei with distinct ploidies exhibit zonation preferences in distribution and asynchrony in maturation. Moreover, by combining gene regulatory network analysis with in vivo genetic manipulation, we identified critical maturation- and zonation-related transcription factors. This study not only delineates the comprehensive transcriptomic profiles of hepatocyte maturation but also presents a paradigm to identify genes that function in the development of hepatocyte maturation and zonation by combining genetic manipulation and measurement of coordinates in a single-cell developmental trajectory.

Benefits of combination therapy with immune checkpoint inhibitors and predictive role of tumour mutation burden in hepatocellular carcinoma: A systematic review and meta-analysis.

OBJECTIVES: To investigate the clinical benefits of combination therapy with immune checkpoint inhibitors (ICIs) and best combination regimen for people with advanced hepatocellular carcinoma (HCC) and to explore the predictive performance of tumour mutation burden (TMB). METHODS: We conducted a systematic literature search to identify clinical trials. Meta-analysis and subgroup analyses were performed to estimate the benefits of combination regimens with PD-1/PD-L1 inhibitors for patients with advanced HCC and compare the effectiveness of PD-1/PD-L1 inhibitors and sorafenib as first-line therapy. Individualized analysis and Kaplan-Meier were used to assess the prognostic value of TMB. RESULTS: A total of 29 studies with 5396 patients were included. ICIs' combination therapy had higher ORR (26 % vs 15 %) and DCR (73 % vs 55 %), longer PFS (5.5 vs 3.1 months) and OS (15.9 vs 12.6 months) compared to monotherapy. Anti-PD-1/PD-L1 agents provided improved ORR, DCR, PFS and OS compared to sorafenib. The overall ORs of ORR and DCR in subgroup analysis were 3.49 (95 % CI 2.36-5.17, p < 0.01) and 1.60 (95 % CI 1.15-2.21, p < 0.01). The overall HRs of PFS and OS were 0.68 (95 % CI 0.48-0.96, p = 0.03) and 0.73 (95 % CI 0.62-0.85, p < 0.01). PD-1/PD-L1 inhibitors plus anti-VEGF agents had an advantage in DCR (0.80 vs 0.48, meta-regression =  - 0.32, P < 0.001), but an equal ORR (0.29 vs 0.26) compared to dual immune checkpoint inhibitors. The total OS in Dua-ICIs were 16.5 months (95 % CI 14.2-18.7), yet not reached in the major studies of ICI plus anti-VEGF regimen. In individualized analysis, the 1-year OS was superior for patients who had high-TMB (>10, mutations/Mb) than moderate-TMB (1-10, mutations/Mb; 28 % vs 15 %, P = 0.025). CONCLUSION: Immune checkpoint inhibitors' combination therapy improved clinical outcomes in the management of advanced hepatocellular carcinoma. However, the overall objective response rate still did not exceed 30%. PD-1/PD-L1 inhibitors plus anti-angiogenic agents and dual immunotherapy provided significantly increased survival over sorafenib, which also pose new challenges for future research, and more appropriate and guided control regimens are required. Also, TMB may be a promising prognostic biomarker for immunotherapy in HCC. However, the validation of prospective and large sample studies is needed.

WWP1 upregulation predicts poor prognosis and promotes tumor progression by regulating ubiquitination of NDFIP1 in intrahepatic cholangiocarcinoma.

WW domain-containing E3 ubiquitin protein ligase1 (WWP1) is reported to be upregulated in many types of human cancers; however, its expression and function in intrahepatic cholangiocarcinoma (ICC) remain unknown. Here, in this study we investigated the expression pattern, clinical prognosis, tumor biological functions, and molecular mechanisms of WWP1 in ICC. The expression of WWP1 in patient tissues was detected by western blotting, immunohistochemistry (IHC), and immunofluorescence. CCK-8, colony formation, EdU, transwell, and xenograft models were used to explore the role of WWP1 in the proliferation and metastasis of ICC. Co-immunoprecipitation, mass spectrometry, chromatin immunoprecipitation, and immunofluorescence were performed to detect the potential mechanisms. Our study revealed that WWP1 was highly expressed in ICC, and high levels of WWP1 were associated with poor prognosis. Functionally, WWP1 overexpression enhanced the proliferation and metastasis of ICC cells and vice versa. Mechanistically, MYC could be enriched in the promoter region of WWP1 to facilitate its expression. Then, WWP1 targets Nedd4 family interacting protein1 (NDFIP1) and reduces NDFIP1 protein levels via ubiquitination. Downregulation of NDFIP1 in ICC cells rescued the effects of silenced WWP1 expression. WWP1 expression was also negatively correlated with the protein level of NDFIP1 in patient tissues. In conclusion, WWP1 upregulated by MYC promotes the progression of ICC via ubiquitination of NDFIP1, which reveals that WWP1 might be a potential therapeutic target for ICC.

Delivery and effects of proton pump inhibitor on anaerobic digestion of food and kitchen waste under ammonia stress.

Ammonia stress changes microbial metabolism of anaerobic digestion and decreases methane yield, where proton pump overactivated by free ammonia suggested to be the centre of the metabolism changes in anaerobic digestion under ammonia stress. The work demonstrated that proton pump inhibitor (PPI) could alleviate the overactivated proton pump and mitigate ammonia inhibition. Its impacts on iron transporter, substrates uptake, and energy conservation were investigated in anaerobic digestion treating food and kitchen waste. The PPI formed a stimuli-responsive drug delivery system driven by pH for the more inhibited microbe (p < 0.01), confirmed by FE-SEM/EDS and high throughput sequencing, implying the PPI was activated at inhibited microbe more than mixed liquor. Consistent microbial population increase observed in syntrophs and methanogens, who utilized the substrates for high yielding pathway and facilitated the energy sharing by direct interspecies electron transfer. These results demonstrated PPI could recovery methane production and could mitigate fatty-acid accumulation under high ammonia stress by delivery and activation in acetoclastic methanogen.

A Triboelectric-Based Artificial Whisker for Reactive Obstacle Avoidance and Local Mapping.

Since designing efficient tactile sensors for autonomous robots is still a challenge, this paper proposes a perceptual system based on a bioinspired triboelectric whisker sensor (TWS) that is aimed at reactive obstacle avoidance and local mapping in unknown environments. The proposed TWS is based on a triboelectric nanogenerator (TENG) and mimics the structure of rat whisker follicles. It operates to generate an output voltage via triboelectrification and electrostatic induction between the PTFE pellet and copper films (0.3 mm thickness), where a forced whisker shaft displaces a PTFE pellet (10 mm diameter). With the help of a biologically inspired structural design, the artificial whisker sensor can sense the contact position and approximate the external stimulation area, particularly in a dark environment. To highlight this sensor's applicability and scalability, we demonstrate different functions, such as controlling LED lights, reactive obstacle avoidance, and local mapping of autonomous surface vehicles. The results show that the proposed TWS can be used as a tactile sensor for reactive obstacle avoidance and local mapping in robotics.

Comparison of an integrated short-cut biological nitrogen removal process with magnetic coagulation treating swine wastewater and food waste digestate.

An integration of two processes, magnetic coagulation (MC) and short-cut biological nitrogen removal (SBNR), coupled with a sequencing batch membrane bioreactor (SMBR) controlled by an automatic real-time control strategy (RTC), was developed to treat different characteristics of high strength wastewater. The treatment efficiency and microbial community-diversity of the proposed method was evaluated and investigated using swine wastewater and food waste (FW) digestate. The MC showed high removal of TSS (89.1 ± 1.5%, 92.21 ± 1.8%), turbidity (90.58 ± 2.1%, 95.1 ± 2.1%), TP (88.5 ± 1.9%, 92.1 ± 1.5%), phosphate (87.76 ± 1.6%, 91.22 ± 1.5%), and SMBR achieved stable and excellent removal of COD (96.05 ± 0.2%, 97.39 ± 0.2%), TN (97.30 ± 0.3%, 97.44 ± 0.3%) andNH4+-N (99.07 ± 0.2%, 98.54 ± 0.2%) for swine wastewater and FW digestate, respectively. The effluent COD andNH4+-N concentrations were found to meet their discharge standards. The microbial community comparison showed similar diversity and richness, and genus Diaphorobacter and Thaurea were dominant in denitritation, and Nitrosomonas was dominant in nitritation treating both swine wastewater and FW digestate.

The performance evaluation and kinetics response of advanced anaerobic digestion for sewage sludge under different SRT during semi-continuous operation.

Sludge retention time (SRT) is vital for advanced anaerobic digestion (AD) to realize energy self-sufficient. However, the criteria on reasonable SRT has not been fully understood. This study investigated the performance and kinetics response of AD under different SRT in semi-continuous AD with microwave (MW) pretreatment, according to the long-term operation and methane production during one feeding interval. Results showed that modified Gompertz model better described the kinetics than first-order model. At short SRT (15 d), pretreatment coupled with two-stage AD preserved methane production with the high attainable methane potential (B0) of 257.98 mL/g VS and hydrolysis rate constant (khyd) of 0.075 h-1. But the acceptable decrease of methane production rate seems to be unavoidable, which was possibly derived from the evolution of methanogenesis pathway. This study emphasized the importance of improved methane production rate in semi-continuous AD under short SRT rather than methane production potential obtained from batch experiment.

N2O emission factors of full-scale animal manure windrow composting in cold and warm seasons.

Emission of nitrous oxide (N2O) during animal manure composting is of great concern, and its emission factor (EF) is important for greenhouse gas emission inventory, while the EF is still uncertain due to limited on-site full-scale observations worldwide. In this study, N2O emissions were monitored during different seasons in a full-scale swine manure windrow composting with pile volume of about 76.5 m3. The results showed that the maximum N2O flux during the cold season (CS) was 23 times higher than during the warm season (WS), significant differences in the contribution to direct N2O emissions were observed in three composting stages, and shaded-side N2O emission was higher than sunny-side emission. The direct N2O emission factors of animal manure composting were 0.0046, 0.0002 kg N2O-N/kgTN (dry weight) in the CS and WS, respectively. Scenario analysis results showed that windrow composting is a suitable manure management that emits less N2O than solid storage.

Effect of zero-valent iron combined with carbon-based materials on the mitigation of ammonia inhibition during anaerobic digestion.

Ammonia inhibition is a prominent problem for anaerobic digestion (AD) of nitrogen-rich organic wastes. This study evaluated the effect of zero valent iron (ZVI) and its hybrid with activated carbon (AC), graphite and Fe-C material on the mitigation of ammonia inhibition under ammonia concentration over 5 g/L, according to the batch mode experiments. Results showed that ZVI (4 g/L) and its hybrid with carbon-based material preserving methane production from ammonia inhibition, with kinetics of shortening lag phase from 4.77 d to 2.62 d or even below 2 d with carbon-based material. ZVI preserved methane production with the enrichment of Methanosarcina (the relative abundance was over 80%), which was mostly derived from the activating hydrogenotrophic methanogenesis through the enhanced DIET but not the changes of ORP and FAN.

Numerical optimization of membrane module design and operation for a full-scale submerged MBR by computational fluid dynamics.

The hydrodynamics in the membrane module of a full-scale sMBR at 500 m3/d was simulated by computational fluid dynamics (CFD) in this study. Several key indexes, including membrane distance (d), aeration design, height of gas-liquid dispersion hm, and freeboard height hf and operational conditions, including SADp and liquid viscosity, were optimized through investigating their impacts on water velocity distribution and membrane shear stress. The CFD model was validated by comparing the simulated trace element RTD curves with experimental results. The optimal design and operational parameters for the full scale sMBR are as following: membrane distance d = 35 mm, air diffusers parallel located 75-100 mm under the bottom of the membrane module, the free board height hf adjusted to 400 mm, and the SADp recommended as 20 in the full-scale MBR studied.

A comprehensive insight into the effects of microwave-H2O2 pretreatment on concentrated sewage sludge anaerobic digestion based on semi-continuous operation.

This study gave a comprehensive insight into the effects of microwave-H2O2 pretreatment on concentrated sludge anaerobic digestion (AD). Results showed that mixture of activated sludge and pretreated sludge at mass ratio of 1:1 was efficient for enhancing AD, methane production was increased from 215.51 mL/g VSadded to 258.38 mL/g VSadded. Pretreatment resulted in the change of sludge properties, such as solubilization of organic matters, decrease of viscosity. For concentrated sludge AD, the "pH buffer system" ensured the "inhibitory steady state" during start-up period, and significant archaeal community shift from Methanosaeta to Methanosarcina ensured the true steady-state operation. Pretreatment further increased the relative abundance of functional microbia such as Bacteroidales, Clostridiales and Methanosarcina, and resulted in the decrease of viscosity of digested sludge in reactors. Based on the CFD simulation, the flow velocity became greater than the control. These comprehensive effects might contribute to enhanced efficiency of concentrated sludge AD.

[Distribution and Treatment of Antibiotics in Typical WWTPs in Small Towns in China].

As a new, persistent pollutant in the environment, antibiotics are one of the most important pollutants in sewage treatment plants. The objective of this work was to investigate the concentration distribution and removal efficiency of antibiotics for three typical wastewater treatment technologies applied in small towns (CASS, A2/O, and Orbal oxidation ditch) using solid phase extraction-liquid chromatography-tandem mass spectrometry. Sixteen typical antibiotics, including four tetracyclines, three ß-lactams, four macrolides, three quinolones, and two sulfonamides, were analyzed in the influent and effluent. In addition, the relationship between the presence of antibiotics and the basic water quality (NH4+-N, TN, COD, pH, etc.) in the WWTPs was analyzed. The results showed that ofloxacin (OFX) and norfloxacin (NOR) were the main antibiotics in the WWTPs in this study. However, the concentrations of these two antibiotics in the effluent were low, indicating effective antibiotic removal efficiency. The antibiotic removal efficiency was higher than 60% in five of the WWTPs. Compared with the A2/O process, the CASS and Orbal oxidation ditch technologies resulted in higher removals of most of the antibiotics. In addition, the CASS and A2/O processes worked best for the removal of ß-lactam [ampicillin (AMP) and penicillin (PCN)], quinolones (ENR, NOR, and OFX), and macrolide (CLR), while the Orbal oxidation ditch worked best for the removal of tetracyclines (TC and OTC) and sulfonamides [sulfadiazine (SD)]. The correlation between antibiotic concentration and the basic parameters of water quality (NH4+-N, TN, COD, pH, etc.) was analyzed, and it was found that the water quality parameters had some effect on the concentration of antibiotics. With higher concentrations of the basic water quality parameters, higher the concentration of erythromycin (EM), roxithromycin (ROX), 4-epi-Tetracycline (E-TC), clarithromycin (CLR), ciprofloxacin (CIP), ofloxacin (OFX), epioxytetracycline (E-OTC), tetracyclines (TC), oxytetracycline (OTC), and norfloxacin (NOR) were observed. In summary, it is important to ensure the stable operation of small town WWTPs to reduce the ecological risk of antibiotics.

Effect of influent C/N ratio on N2O emissions from anaerobic/anoxic/oxic biological nitrogen removal processes.

The problem of producing strong greenhouse gas of nitrous oxide (N2O) from biological nitrogen removal (BNR) process in wastewater treatment plants (WWTP) has elicited great concern from various sectors. In this study, three laboratory-scale wastewater treatment systems, with influent C/N ratios of 3.4, 5.4, and 7.5, were set up to study the effect of influent C/N ratio on N2O generation in anaerobic/anoxic/oxic (A2O) process. Results showed, with the increased influent C/N ratio, N2O generation from both nitrification and denitrification process was decreased, and the N2O-N conversion ratio of the process was obviously reduced from 2.23 to 0.05%. Nitrification rate in oxic section was reduced, while denitrification rate in anaerobic and anoxic section was elevated and the removal efficiency of COD, NH4+-N, TN, and TP was enhanced in different extent. As the C/N ratio increased from 3.4 to 7.5, activities of three key denitrifying enzymes of nitrate reductase, nitrite reductase, and nitrous oxide reductase were increased. Moreover, microorganism analysis indicated that the relative abundance of ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) were positively correlated with N2O generation, which was reduced from (8.42 ± 3.65) to (3.61 ± 1.66)% and (10.38 ± 4.12) to (4.67 ± 1.62)%, respectively. NosZ gene copy numbers of the A2O system were increased from (1.19 ± 0.49) × 107 to (2.84 ± 0.54) × 108 copies/g MLSS with the influent C/N ratio elevated from 3.4 to 7.5. Hence, appropriate influent C/N condition of A2O process could optimize the microbial community structure that simultaneously improve treatment efficiency and decrease the N2O generation.

Numerical simulation of scaling-up for AEC-MBRs regarding membrane module configurations and cyclic aeration modes.

The airlift external circulation membrane bioreactors (AEC-MBRs) have been attracting attentions due to their capabilities of nutrient removal with lower energy demand and smaller footprint. The gap between laboratory study and full-scale AEC-MBRs regarding hydrodynamics needs to be addressed. In this study, impacts of seven design variables and cyclic aeration modes on hydrodynamics were studied for the scale-up of AEC-MBRs with computational fluid dynamics modelling. The results demonstrated that shear stress on membranes was 14.7% higher in full-scale MBR with only 15% of SADm of lab-scale MBR while it showed an overall higher sensitivity to the design variables in lab-scale MBRs. Cyclic aeration modes created a sinusoidal pattern of shear stress and generated more fluctuations and were expected to reduce more irreversible fouling. When a shifting frequency of 5s/5s was applied in AEC-MBR, 50% of aeration energy was reduced and yield water with good quality was harvested.