Deciphering the role of micro/nano-hydroxyapatite in aerobic granular sludge system: Effects on treatment performance and enhancement mechanism.

Hydroxyapatite (HAP), a mineral nucleus identified within aerobic granular sludge (AGS), plays a vital role in enhancing the AGS systems. However, the microscopic mechanism underlying their roles remains largely unexplored. Herein, a systematic investigation was carried out to elucidate the impact and enhanced mechanisms associated with HAP of different sizes, i.e. micro-HAP (mHAP) and nano-HAP (nHAP), on the aerobic granulation, nutrient removal and microbial diversity of AGS. Results showed that the presence of nHAP and mHAP significantly shortened the granulation process to 15 and 20 days, respectively. This might be ascribed to the fact that the large specific surface area of nHAP aggregates was conducive to microbial adhesion, biomass accumulation and sludge granulation. Compared with mHAP, the granules with nHAP showed better settlement performance, mechanical strength and larger diameter. The X-ray diffraction (XRD) and Raman spectrometer analysis confirmed the presence of HAP within the granules, which was found to stimulate the secretion of extracellular polymeric substance, improve the compactness of granule structure and suppress the growth of filamentous bacteria, thereby contributing to a stable AGS system. The presence of HAP, especially nHAP, effectively enriched the functional microorganisms, such as nitrifying and denitrifying bacteria (e.g. Candidatus_Competibacter) and phosphorus accumulating organisms (e.g. Flavobacterium), leading to the improved nutrient removal efficiencies (COD > 96%, TN > 76%, and TP > 74%). Further analysis revealed the up-regulation of functional enzymes (e.g. nitrite oxidoreductase and polyphosphate kinase) involved in nutrient metabolism, underlying the inherent mechanisms for the excellent nutrient removal. This study deepens the understanding of granulation mechanisms from the perspective of mineral cores, and proposes an economically feasible strategy for rapid initiation and stabilization of AGS reactors.

Association between platelet­to­lymphocyte ratio and serum prostate specific antigen.

There is evidence that the systemic inflammatory response may have an impact on prostate-specific antigen (PSA) levels. However, the relationship between the platelet-to-lymphocyte ratio (PLR) and PSA remains unclear. As a result, the relationship between PLR and PSA using the National Health and Nutrition Examination Survey (NHANES) database was examined. After the screening, 6,638 participants out of 52,186 in the NHANES survey conducted between 2001 to 2010 were suitable for the present study. The PLR was the independent variable in the present study, and PSA was the dependent variable. The selected subjects in the present study had an average age of 58.563±11.848 years. After controlling for covariates, the results showed that with every increase in PLR, the PSA concentration increased by 0.004 ng/ml (0.001, 0.007). This difference was statistically significant. Furthermore, a smoothing curve based on a fully adjusted model was created to investigate the possibility of a linear relationship between PLR and PSA concentration in men from USA. In men from USA, an independent and positive correlation between PLR and PSA was identified, which could potentially result in overdiagnosis of asymptomatic prostate cancer in populations with higher PLR levels.

Mechanisms underlying the detrimental impact of micro(nano)plastics on the stability of aerobic granular sludge: Interactions between micro(nano)plastics and extracellular polymeric substances.

Microplastics (MPs) and nanoplastics (NPs) present in wastewater can pose a negative impact to aerobic granular sludge (AGS). Herein, this study found that MPs and NPs (20 mg/L) deteriorated the sludge settleability and granule integrity, resulting in a 15.7 % and 21.9 % decrease in the total nitrogen removal efficiency of the AGS system, respectively. This was possibly due to the reduction of the extracellular polymeric substances (EPS) content. The subsequent analysis revealed that tyrosine, tryptophan, and humic acid-like substances in EPS exhibited a higher propensity for chemisorption and inhomogeneous multilayer adsorption onto NPs compared to MPs. The binding of EPS onto the surface of plastic particles increased the electronegativity of the MPs, but facilitated the aggregation of NPs through reducing the electrostatic repulsion, thereby mitigating the adverse effects of MPs/NPs on the AGS stability. Additionally, comprehensive analysis of the extended Derjaguin-Landau-Verwey-Overbeek theory indicated that the suppressed aggregation of microorganisms was the internal mechanisms contributing to the inadequate stability of AGS induced by MPs/NPs. This study provides novel insights into the detrimental mechanisms of MPs/NPs on the AGS stability, highlighting the key role of EPS in maintaining the structural stability of AGS when exposed to MPs/NPs.

Metagenomic analysis reveals the responses of microbial communities and nitrogen metabolic pathways to polystyrene micro(nano)plastics in activated sludge systems.

Microplastics (MPs) and nanoplastics (NPs) are prevalent in sewage and pose a potential threat to nitrogen biotransformation in wastewater treatment systems. However, investigations on how MPs and NPs affect the microbial nitrogen conversion and metabolism of the activated sludge are still scanty. Herein, the responses of microbiomes and functional genes to polystyrene MPs and NPs in activated sludge systems were investigated by metagenomic analysis. Results indicated that 1 mg/L MPs and NPs had marginal impacts on the nitrogen removal performance of the activated sludge systems, whereas high concentrations of MPs and NPs (20 and 100 mg/L) decreased the total nitrogen removal efficiency (13.4%-30.6%) by suppressing the nitrogen transformation processes. Excessive reactive oxygen species induced by MPs and NPs caused cytotoxicity, as evidenced by impaired cytomembranes and decreased bioactivity. Metagenomic analysis revealed that MPs and NPs diminished the abundance of denitrifiers (e.g. Mesorhizobium, Rhodobacter and Thauera), and concurrently reduced the abundance of functional genes (e.g. napA, napB and nirS) encoding for key enzymes involved in the nitrogen transformations, as well as the genes (e.g. mdh) related to the electron donor production, thereby declining the nitrogen removal efficiency. Network analysis further clarified the attenuate association between denitrifiers and denitrification-related genes in the plastic-exposed systems, elucidating that MPs and NPs restrained the nitrogen removal by inhibiting the contributions of microorganisms to nitrogen transformation processes. This study provides vital insights into the responses of the microbial community structure and nitrogen conversion processes to micro(nano)plastics disturbance in activated sludge systems.

Revealing the influencing mechanisms of polystyrene microplastics (MPs) on the performance and stability of the algal-bacterial granular sludge.

Algal-bacterial granular sludge (ABGS) is an energy-saving and environment-friendly wastewater treatment technology; however, the effects of microplastics (MPs) on the performance and stability of the ABGS system remain unknown. Herein, the influencing mechanisms of polystyrene MPs (50 µm) on the ABGS were systematically investigated. The ABGS exhibited a high removal efficiency of MPs (over 96%) at 1 mg/L and 20 mg/L. Although the biomass content, sludge settling and particle size were not obviously affected by MPs, the COD and total phosphorus (TP) removal efficiencies were inhibited by 2.6%-4.1% and 2.9%-5.8%, respectively. Meanwhile, the structural stability of ABGS was damaged by MPs, owing to the excessive oxidative stress, low content of protein-like substance (especially tryptophan and tyrosine), and the large portion of loose protein secondary structure. Microbial community analysis revealed that the relative abundance of some functional bacteria (Candidatus_Competibacter and Rhodobacter) and algal species (Tetradesmus) were decreased under the MPs stress.

Effect of low-intensity ultrasound on partial nitrification: Performance, sludge characteristics, and properties of extracellular polymeric substances.

Ultrasound technology, which is environment-friendly and economical, has emerged as a novel strategy that can be used to enhance the partial nitrification process. However, its effect on this process remains unclear. Therefore, in this study, partial nitrification sludge was subjected to low-intensity (0.15 W/mL) ultrasound treatment for 10 min, and the effect of ultrasonic treatment on the partial nitrification process was evaluated based on changes in reactor performance, sludge characteristics, and the properties of extracellular polymeric substances (EPS). The results obtained showed that the ultrasonic treatment enhanced nitrite accumulation performance as well as the activity of ammonia-oxidizing bacteria from 3.3 to 16.6 mg O2/g VSS,⋅while inhibiting the activity of nitrite-oxidizing bacteria. Further analysis showed that owing to the ultrasonic treatment, there was an increase in EPS contents. Particularly, there was a significant increase in loosely bound polysaccharide (PS) contents, indicating the occurrence of intracellular PS anabolics as well as PS secretion. Additionally, ultrasonic treatment induced a significant increase in carbonyl, hydroxyl, and amine functional group contents, and EPS analysis results revealed that it had a positive effect on mass transfer efficiency; thus, it enhanced the partial nitrification process. Overall, this study describes the effect of intermittent low-intensity ultrasound on the partial nitrification process as well as the associated enhancement mechanism.

Prognostic value of peripheral blood T lymphocyte subsets in clear cell renal cell carcinoma.

BACKGROUND: To date, few studies have evaluated the role of peripheral blood T lymphocyte subsets in patients with clear cell renal cell carcinoma (ccRCC). Here we measured the levels of peripheral blood T lymphocyte subsets and evaluated its prognostic value in ccRCC. METHODS: Data from 122 patients with RCC from January 2018 to January 2020 were collected. Preoperative peripheral blood T lymphocyte subsets and medical records were analyzed. Kaplan-Meier cures and log rank test were used for analyzing overall survival (OS). Univariate and multivariate survival analyses were underwent by performing the Cox proportional hazards models. Correlations were tested by Pearson's correlation analysis. RESULTS: Of 122 patients, a total of 80 ccRCC patients was enrolled. Patients with low CD3+ T cells and low CD4+/CD8+ ratio displayed a worse OS than patients with high CD3+ T cells and high CD4+/CD8+ ratio (P=0.029 and 0.002, respectively). Multivariate analyses showed CD3+ T cells and CD4+/CD8+ ratio were independent predictive factors for the OS (HR: 0.295, 95% CI, 0.091-0.956; P=0.042 and HR: 0.244, 95% CI, 0.065-0.920; P=0.037, respectively). Moreover, NLR negatively correlated with both levels of CD3+ T cells and CD4+/CD8+ ratio (P<0.001, r=-0.398 and P=0.012, r=-0.280, respectively). CONCLUSIONS: The findings of our study suggest that preoperative CD3+ T cells and CD4+/CD8+ ratio in peripheral blood are independent predictors for patients with ccRCC.

Effects of low-intensity ultrasound on nitrite accumulation and microbial characteristics during partial nitrification.

Ultrasound technology has attracted increasing attention in the field of sewage sludge treatment. This study investigated the nitrite accumulation ratio (NAR) and microbial characteristics of the partial nitrification (PN) process in a sequencing batch reactor employing ultrasonic treatment (ultrasound density = 0.25 W/mL, irradiation time = 10 min). PN was achieved over 73 days with a NAR above 85% under ambient temperatures. A low dissolved oxygen (DO) environment was generated in the reactor by enhancing the oxygen utilization rate of ammonia-oxidizing bacteria (AOB). Additionally, the application of long-term ultrasonic treatment led to the enhancement of the dominance of the Nitrosomonas genus of AOB, while populations of the Nitrospira genus of nitrite-oxidizing bacteria (NOB) were eradicated. At the same time, the activities of the aerobic denitrifying bacteria Thauera, Terrimonas, Defluviimonas, and Thermomonas were enhanced and their relative abundance was increased. Overall, the results suggest that ultrasonic treatment can enhance AOB activity and generate a low DO environment that facilitates effective PN.

Enhancement in the partial nitrification of wastewater sludge via low-intensity ultrasound: Effects on rapid start-up and temperature resilience.

The partial nitrification process can reduce the aeration energy consumption in bioreactors by 25%. Low-intensity ultrasound (0.25 W·mL-1) was applied during the partial nitrification process to evaluate its effects on start-up and temperature resilience. Ultrasound application led to rapid start-up of the partial nitrification process (within 18 d) with a nitrite accumulation ratio of above 80% at 18 °C. Moreover, when the temperature was increased to 28 °C, the partial nitrification process was effectively maintained with a nitrite accumulation ratio of above 80%. Ultrasonic treatment for a long duration had a positive effect on ammonia oxidizing bacteria of the genus Nitrososphaera, whereas the population of nitrite oxidizing bacteria, Nitrospira, decreased. The temperature resilience of Nitrososphaera was also enhanced. These findings indicate that ultrasound induces rapid start-up of the partial nitrification process and enhances the temperature resilience of Nitrososphaera.