Physicochemical Properties and Hypolipidemic Activity of Dietary Fiber from Rice Bran Meal Obtained by Three Oil-Production Methods.

This study investigated the effects of three oil production methods on the physicochemical properties of dietary fiber from rice bran flour, and the hypolipidemic effects of the dietary fibers were investigated in vitro and in vivo. The particle size results showed that the organic-solvent-impregnated rice bran meal dietary fiber (N-RBDF) had the smallest average particle size and the aqueous enzymatic rice bran meal dietary fiber (E-RBDF) had the narrowest particle size distribution. Scanning electron microscopy (SEM) results demonstrated that all three kinds of rice bran meal dietary fibers (RBDFs) were irregularly flaky. Fourier transform infrared spectroscopy (FT-IR) results revealed that the three RBDFs had similar reactive groups, and X-ray diffraction (XRD) results indicated that all three RBDFs were cellulose type I crystals. The results of thermogravimetric analysis showed that the lignin content of N-RBDF was significantly lower than that of the other two. Among the three kinds of RBDFs, E-RBDF had higher water retention capacity, swelling capacity, oil holding capacity, and adsorption capacity for cholesterol and sodium bile salts. The results of experimental studies in hyperlipidemic rats showed that all three kinds of RBDFs significantly reduced triglycerides (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) and elevated high-density lipoprotein cholesterol (HDL-C) in the serum of hyperlipidemic rats; they also significantly lowered malondialdehyde (MDA) and elevated total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) activities in the livers of rats. In addition, all three kinds of RBDFs decreased aminotransferase (ALT) and aminotransferase (AST) activity in serum and also improved liver steatosis and reduced atherosclerosis index (AI) in rats with hyperlipidemia. Our study provides a reference for the development and utilization of rice bran meal and the application of rice bran meal dietary fiber in food processing.

Physicochemical properties of superfine grinding-microwave modified artichoke soluble dietary fiber and their alleviation of alcoholic fatty liver in mice.

The effects of superfine grinding (SG) and microwave treatment (MT) on the structure and physicochemical properties of artichoke soluble dietary fiber (ASDF) and its protective effects on mice with alcoholic fatty liver (AFL) were studied. We compared the changes in structural characteristics and physicochemical properties of ASDF, SG-ASDF (ASDF treated by SG), MT-ASDF (ASDF treated by MT), and CM-ASDF (ASDF treated by SG and MT). Moreover, we evaluated the effects of the obtained ASDF on the growth characteristics, blood lipid levels, and liver of mice with AFL. Our results of the study showed that CM-ASDF had a more concentrated and uniform particle size, a higher extraction rate of ASDF and significantly improved water-holding capacity (WHC), oil-holding capacity (OHC) and water swelling capacity (WSC) of ASDF (p < 0.05). After the ASDF intervention, mice with AFL exhibited a significant improvement in body lipid levels and reduce liver inflammation. Specifically, aspartate aminotransferase (AST), alanine aminotransferase (ALT), malonaldehyde (MDA), Tumor necrosis factor-α (TNF-α) and Interleukin-6 (IL-6) were significantly decreased, while superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) were significantly increased (p < 0.05). And the hematoxylin-eosin (HE) staining results showed significant improvement of hepatic steatosis in mice with AFL. In summary, our study found that both SG and MT could improve the structure and physicochemical properties of ASDF, with CM-ASDF being the most effective. Additionally, CM-ASDF was selected to continue the investigation and demonstrated an excellent protective effect on mice with AFL, with the high dose group (H-ASDF) showing the greatest benefit. These findings provided some new insights for future comprehensive utilization of ASDF and drug development for the treatment of AFL.

Radiomic Analysis of Quantitative T2 Mapping and Conventional MRI in Predicting Histologic Grade of Bladder Cancer.

We explored the added value of a radiomic strategy based on quantitative transverse relaxation (T2) mapping and conventional magnetic resonance imaging (MRI) to evaluate the histologic grade of bladder cancer (BCa) preoperatively. Patients who were suspected of BCa underwent pelvic MRI (including T2 mapping and diffusion-weighted imaging (DWI) before any treatment. All patients with histological-proved urothelial BCa were included. We constructed different prediction models using the mean signal values and radiomic features from both T2 mapping and apparent diffusion coefficient (ADC) maps. The diagnostic performance of each model or parameter was assessed using receiver operating characteristic curves. In total, 92 patients were finally included (training cohort, n = 64; testing cohort, n = 28); among these, 71 had high-grade BCa. In the testing cohort, the T2-mapping radiomic model achieved the highest prediction performance (area under the curve (AUC), 0.87; 95% confidence interval (CI), 0.73-1.0) compared with the ADC radiomic model (AUC, 0.77; 95%CI, 0.56-0.97), and the joint radiomic model of 0.78 (95%CI, 0.61-0.96). Our results demonstrated that radiomic mapping could provide more information than direct evaluation of T2 and ADC values in differentiating histological grades of BCa. Additionally, among the radiomic models, the T2-mapping radiomic model outperformed the ADC and joint radiomic models.

Modification of Artichoke Dietary Fiber by Superfine Grinding and High-Pressure Homogenization and Its Protection against Cadmium Poisoning in Rats.

This study was carried out to investigate the effects of superfine grinding (SP) and high-pressure homogenization (HPH) on the structural and physicochemical properties of artichoke dietary fiber (ADF), as well as the protective effects against cadmium poisoning in rats. The structural characteristics and physicochemical properties of ADF, HPH-ADF (ADF treated by HPH) and CM-ADF (ADF treated by SP and HPH) were determined, and cadmium chloride (CdCl2) was induced by exposing rats for 7 weeks. The amounts of creatinine and urea; the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) in serum; the quantity of red blood cells, hemoglobin, white blood cells and neutrophil proportion in blood samples; and the activity of glutathione peroxidase (GSH-Px) in liver tissue were analyzed. Hematoxylin-eosin (HE) staining was performed to analyze the tissue structure and pathology of the liver and testis. The results showed that ADF subjected to HPH and SP-HPH exhibited increased content of soluble dietary fiber (SDF) (p < 0.05). HPH and SP-HPH treatments increased oil-holding capacity (OHC), total negative charge (TNC) and heavy metal adsorption capacity (p < 0.05). The CdCl2 intervention led to a significant increase in AST, ALT, creatinine, urea, neutrophil proportion and white blood cell count, as well as a significant decrease in GSH-Px activity, red blood cell count and hemoglobin (HGB) (p < 0.05). In rats fed with ADF, HPH-ADF and CM-ADF significantly reduced creatinine, urea amounts, ALT, AST activity in serum, leukocyte count and the neutrophil ratio in blood and increased GSH-Px activity in the liver, in addition to increasing the erythrocyte count and hemoglobin count in blood (p < 0.05). H&E staining results showed that steatosis in the liver was significantly reduced, whereas testicular tissue edema was improved. These results indicate that ADF exhibited positive activity against cadmium poisoning in rats and that CM-ADF had a better protective effect than ADF and HPH-ADF. ADF has specific potential to be used in health foods or therapeutic drugs, providing a reference for the development and utilization of artichoke waste.

Novel Control Strategy for Membrane Biofouling by Surface Loading of Aerobically and Anaerobically Applicable Photocatalytic Optical Fibers Based on a Z-Scheme Heterostructure Zr-MOFs/rGO/Ag3PO4 Photocatalyst.

The high replacement cost of modified membranes in antibiofouling application is inevitable. Here, surface-loaded photocatalytic optical fibers (POFs) were developed as antibiofouling strategies to replace membrane modification. To prepare aerobically and anaerobically applicable POFs, novel visible light-driven zirconium-based metal-organic framework/reduced graphene oxide/Ag3PO4 (Zr-MOFs/rGO/Ag3PO4) Z-scheme heterojunctions were constructed and coated on optical fibers. After loading the POFs on the membrane surface, the antibiofouling capability of the POFs was demonstrated during membrane filtration of bacteria and foulants under visible light irradiation. The disinfection efficiencies of the POFs against Escherichia coli and Staphylococcus aureus reached 95.7 and 92.4%, respectively, by aerobic treatment and 90.3 and 85.5%, respectively, by anaerobic treatment. For the inactivated bacteria, cell membrane and membrane-associated functions were destroyed, accompanied by antioxidant enzyme decomposition, loss of cell respiration and adenosine triphosphate (ATP) synthesis capacity, and leakage and oxidation of protein, lipid, potassium, DNA, and RNA. During membrane filtration of model foulants and membrane bioreactor sludge, the POFs significantly alleviated the membrane flux decline by foulant disintegration. By qualitative and quantitative detection and quenching tests of reactive species, aerobically generated •O2- and •OH and anaerobically generated •OH from POFs played dominant roles in the antibiofouling process. This work provides unique insights into membrane fouling control based on environmentally friendly and efficient photocatalytic technology.

Effects of environmental aging on the adsorption behavior of antibiotics from aqueous solutions in microplastic-graphene coexisting systems.

The extensive use of nanofillers, such as graphene oxide (GO) and reduced graphene oxide (rGO), as plastic additives has led to the coexistence of microplastics (MPs) and nanomaterials in aquatic environments. However, there is a lack of studies on the adsorption behavior of MPs when coexisting with GO. Moreover, MPs and GO are prone to undergoing aging processes in real environments under conditions such as sunlight exposure, which changes their physicochemical properties and affects their adsorption behavior. In this study, the aging processes of MPs and GO in a real environment were simulated by ultraviolet (UV) irradiation and thermal treatments, respectively. The adsorption behavior of ciprofloxacin (CIP) on three types of MPs (polypropylene (PP), polyamide (PA), and polystyrene (PS)) before and after aging was explored. The MPs are ordered in terms of CIP adsorption capacity as aged-PA > aged-PS > aged-PP > PA > PP > PS, and the adsorption capacity of aged MPs was approximately twofold higher than that of pristine MPs. This paper also studied the adsorption performance of antibiotics in a coexisting system of aged MPs and GO/rGO, and the tetracycline (TC) adsorption capacity was increased by ~336% in aged PP-GO and ~100% in an aged PP-rGO coexisting system. GO/rGO with high degree of oxidation and concentration in an aged- PP-GO/rGO coexisting system are more conducive to the TC adsorption, due to the contribution of oxygen-containing functional groups. Surface and partition adsorption co-occurred during the TC adsorption process. The TC adsorption behavior in the MPs-GO/rGO coexisting system was strongly dependent on the solution pH, which was more favorable under acidic (pH = 3) or alkaline (pH = 11) conditions. This study improves the understanding of the environmental behavior of MPs, graphene, and antibiotics and guides research on strategies for preventing the migration of antibiotics in MPs-GO/rGO coexisting systems.

Novel strategy for membrane biofouling control in MBR with CdS/MIL-101 modified PVDF membrane by in situ visible light irradiation.

Novel control strategies for membrane biofouling with eco-friendly photocatalytic technology are critically needed in practical operation of membrane bioreactors (MBRs). In this study, a metal-organic frameworks (MOF) based photocatalytic membrane was firstly applied in an anammox MBR for a long-term biofouling control, where bacteria were inactivated and foulants were degraded simultaneously, with environmentally friendly and renewable visible light energy. By physicochemical characterization, the synthesized photocatalyst of CdS/MIL-101 showed superior visible-light photocatalytic ability, and the 1 wt% CdS/MIL-101 modified membrane C2 showed enhanced hydrophilicity and water permeability compared with the pristine membrane C0. In the long-term operation of anammox MBRs under waterproof lights irradiation, the filtration cycles of C2 (25-26 d) were obviously extended compared with C0 (10-14 d), while their average total nitrogen removal efficiencies were comparable up to 84%, indicating an excellent biofouling alleviation effect by using C2 with a satisfactory nitrogen removal performance maintained. By analysis of the biofilm on the fouled membranes, the organic foulants (especially extracellular polymeric substances) were degraded, and the live bacteria were inactivated effectively by the photocatalytic reactions of CdS/MIL-101 on C2. In the antimicrobial tests against model bacteria, C2 exhibited remarkable antimicrobial effect against both Gram-negative and Gram-positive bacteria with visible light irradiation by destruction of cell integrity with the inhibition rate of 92% for Escherichia coli and 95% for Staphylococcus aureus, respectively. In the model foulants (bovine serum albumin, sodium alginate, and humic acid) filtration tests, C2 showed higher antifouling capabilities, lower flux declining rates, and higher foulants rejection rates under visible light irradiation compared with C0. The reactive species of ·OH, e- and h+ generated on C2 were verified to play the predominant role in the anti-biofouling processes by simultaneous bacteria inactivation and foulants degradation. The findings offer a novel insight into the biofouling controlling in MBRs by simultaneous bacteria inactivation and foulants degradation with an eco-friendly method.

Comparison of short-term dosing ferrous ion and nanoscale zero-valent iron for rapid recovery of anammox activity from dissolved oxygen inhibition.

As obligate anaerobes, anammox bacteria are sensitive to oxygen, which might hinder the maximization of anammox activity. However, there are very few effective strategies to rapidly recover anammox activity after its deterioration under exposure of oxygen. In this study, the activity recovery of anammox bacteria encountering dissolved oxygen (DO) exposure (0.2 and 2.0 mg L-1) were compared by three strategies in short-term experiments, nZVI, Fe(II) dosing, and N2 purging. nZVI is more effective in recovering anammox activity with a high DO exposure (2 mg L-1), compared to a low DO exposure (0.2 mg L-1). After inhibiting by 2.0 mg L-1 DO, anammox activity recovery (normalized to the control) was ranked in the order of nZVI (5 mg L-1) addition (63 ±â€¯8.2%) > Fe(II) (5 mg L-1) addition (41 ±â€¯8.0%) >N2 purging (39 ±â€¯4.0%). In contrast to Fe(II) ion additions, the shell structure of nZVI combined with the buffering effect of biomass-extracellular polysaccharide (EPS) prevented the sharp pH variation and excessive dissolved Fe(II)/Fe(III) in solution. Under such circumstances, nZVI addition (5 and 25 mg L-1) increased the intracellular reactive oxygen species (ROS) to a moderate level (<200%), which might be responsible for the better activity recovery of anammox than that of Fe(II) addition and N2 purging. Specifically, 5 mg L-1 nZVI dosage moderately enhanced the intracellular O2- production (∼150% of the control) after scavenging 2.0 mg L-1 DO, and the anammox activity recovered better than that of both 5 and 25 mg L-1 Fe(II) ions additions. However, high dosage nZVI (75 mg L-1) inhibited anammox activity in spite of low or high DO exposure. Our findings elucidate that appropriate amount of nZVI (short-term dosing) can rapidly recover anammox activity when anammox bacteria encountering oxygen exposure accidentally and could be useful in facilitating the robust operation of anammox-based processes.

Inflammatory cytokine profiles in eyes with primary angle-closure glaucoma.

Acute primary angle-closure (APAC) eyes show an early 'acute inflammatory' condition, while the inflammation condition has not been fully elucidated in the development of primary angle-closure glaucoma (PACG). To evaluate the roles of inflammatory cytokines in the pathogenesis of PACG, this cross-sectional study involved 40 eyes of 32 PACG patients who required trabeculectomy and 24 eyes of 24 patients who required cataract surgery. The aqueous humor samples were collected at the time of surgery. Fifteen inflammatory cytokines were detected using the multiplex bead immunoassay technique, and the clinical information was recorded for the correlation analysis. Eight of the 15 cytokines were all detectable in both groups, including granulocyte colony-stimulating factor (G-CSF), interleukin (IL)-6, IL-8, monocyte chemotactic protein (MCP)-1, MCP-3, macrophage-derived chemokine (MDC), macrophage inflammatory protein (MIP)-1ß, and vascular endothelial growth factor (VEGF). When compared with the cataract patients, the MCP-3, MDC, and VEGF levels were elevated in the PACG patients, while the MCP-1 and MIP-1ß levels were decreased. However, the G-CSF, IL-6, and IL-8 levels were similar between the two groups. The MCP-1 concentration was elevated accordingly as the disease progressed in the PACG patients. Our results suggest the PACG eyes retained a 'mild inflammation' condition in the aqueous humor, and MCP-1 may play an important role in the progression of this disease.

microRNA Profiling in Glaucoma Eyes With Varying Degrees of Optic Neuropathy by Using Next-Generation Sequencing.

Purpose: To explore the microRNA (miRNA) profile and its putative role in glaucomatous optic neuropathy by using next-generation sequencing. Methods: Aqueous humor (AH) samples were collected from 19 primary open-angle glaucoma (POAG) eyes and 17 cataract eyes before surgery. Next-generation sequencing was performed for RNA samples extracted from 18 AH samples, and the bioinformatics approach was applied for samples with adequate clean data output. The other 18 samples were used for quantitative PCR validation of sequencing results. Results: In total, 12 (six POAG and six cataract controls) samples with sufficient clean data output after sequencing were used for further data analysis. Four hundred sixty-six and 480 mature miRNAs were detected in the POAG and cataract control groups, respectively. Among them, 164 miRNAs were detected in all POAG samples, and 96 miRNAs were detected in all cataract control samples. Furthermore, 88 miRNAs were identified as differently expressed between POAG and cataract control eyes. In addition, 16 miRNAs were differently expressed between POAG eyes with severe visual field damage and eyes with moderate visual field damage. This differential expression was predicted to regulate thiamine metabolism, purine metabolism, and transcriptional misregulation. Relative expression patterns of hsa-miR-184, hsa-miR-486-5p, and hsa-miR-93-5p were confirmed by quantitative PCR. Conclusions: This study comprehensively demonstrated the miRNA expression profile in the AH of POAG eyes, especially the differential expression of miRNA in eyes with varying degrees of visual field damage, which, together with the underlying miRNA-related pathways, indicate new targets for the pathogenesis and progression of POAG.

Comparison of enhancement of anaerobic digestion of waste activated sludge through adding nano-zero valent iron and zero valent iron.

The feasibility of adding nano-zero valent iron (NZVI: 0.6, 1.0, 4.0, 10.0 g L-1) to enhance anaerobic digestion of waste activated sludge (WAS) was examined by comparison with ZVI, and the mechanisms of NZVI enhancement of the hydrolysis and methanogenesis processes were elucidated. NZVI could enhance hydrolysis-acidification of WAS by destroying the integrity of microbial cells. Both volatile fatty acids production and the acetic acid portion were greatly improved by NZVI additions, peaking at 4.0 g L-1 NZVI. In anaerobic digestion, CH4 production was promoted at a NZVI dosage ≤1.0 g L-1. The optimum dosage of NZVI for methanogenesis was 1.0 g L-1, and further addition of NZVI could cause inhibition of methanogenesis because of long-term accumulation of H2. ZVI could also improve hydrolysis-acidification and the CH4 yield, but its efficiency was relatively low compared with NZVI, and it could not induce cell wall rupture. 16S rDNA high-throughput sequencing results showed that NZVI addition at appropriate dosage facilitated increasing the proportion of microorganisms involved in WAS hydrolysis-acidification and methanogenesis.

Comparison of anterior cervical discectomy and fusion with the zero-profile device versus plate and cage in treating cervical degenerative disc disease: A meta-analysis.

Zero-profile device was applied to diminish the irritation of the esophagus in the treatment of cervical degenerative disc disease. However, the clinical application of the zero-profile device has not been testified with clinical evidence. The aim of the meta-analysis was to systematically compare the safety and effectiveness of anterior cervical discectomy and fusion with zero-profile device with plate and cage for the treatment of cervical degenerative disc disease. Electronic searches of PubMed and Embase were conducted up to May 2015. Relevant studies were included. Weighted mean difference (WMD) and 95% confidence intervals (CI) were assessed for continuous data. Risk ratio (RR) and 95% CI were assessed for dichotomous data. P value <0.05 was considered to be significant. Eleven studies were included in the meta-analysis. Compared with plate and cage, zero-p is associated with lower operation time of two-level surgery, less intraoperative blood loss, higher subsidence rate, higher JOA score, lower incidence of dysphagia in short-term (RR: 0.72, 95% CI [0.58, 0.90], P=0.005, I2=22%) and long-term (RR: 0.12, 95% CI [0.05, 0.30], P<0.00001, I2=0%) and lower Cobb angle of multilevel surgery (WMD: -3.16, 95% CI: [-4.35, -1.97], P<0.00001, I2=0%). No significant difference was found in one-level and two-level Cobb angle, fusion rate and operation time of one-level and three-level surgery. Both zero-p implantation and the plate and cage have respective advantages and disadvantages.

Comparison of endogenous metabolism during long-term anaerobic starvation of nitrite/nitrate cultivated denitrifying phosphorus removal sludges.

Denitrifying phosphorus removal (DPR) by denitrifying phosphorus-accumulating organisms (DPAOs) is a promising approach for reducing energy and carbon usage. However, influent fluctuations or interruptions frequently expose the DPAOs biomass to starvation conditions, reducing biomass activity and amount, and ultimately degrading the performance of DPR. Therefore, a better understanding of the endogenous metabolism and recovery ability of DPAOs is urgently required. In the present study, anaerobic starvation (12 days) and recovery were investigated in nitrite- and nitrate-cultivated DPAOs at 20 ± 1 °C. The cell decay rates in nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were 0.008 day⁻¹ and 0.007 day⁻¹, respectively, being 64% and 68% lower than those of nitrate-DPAOs sludges. Nitrite-DPAOs sludges also recovered more rapidly than nitrate-DPAOs sludge after 12 days of starvation. The maintenance energy of nitrite-DPAOs sludges from the end of the anaerobic and aerobic phase were approximately 31% and 34% lower, respectively, than those of nitrate-DPAOs sludges. Glycogen and polyphosphate (poly-P) sequentially served as the main maintenance energy sources in both nitrite-and nitrate-DPAOs sludges. However, the transformation pathway of the intracellular polymers during starvation differed between them. Nitrate-DPAOs sludge used extracellular polymeric substances (EPS) (mainly polysaccharides) as an additional maintenance energy source during the first 3 days of starvation. During this phase, EPS appeared to contribute to 19-27% of the ATP production in nitrate-DPAOs, but considerably less to the cell maintenance of nitrite-DPAOs. The high resistance of nitrite-DPAOs to starvation might be attributable to frequent short-term starvation and exposure to toxic substances such as nitrite/free nitrous acids in the parent nitrite-fed reactor. The strong resistance of nitrite-DPAOs sludge to anaerobic starvation may be exploited in P removal by shortcut denitrification processes.

The Thr241Met polymorphism in the XRCC3 gene is associated with increased risk of cancer in Chinese mainland populations.

The Thr241Met polymorphism in XRCC3 gene may affect the DNA repair pathways and be associated with the risk of cancer. However, the results of previous studies are inconsistent in Chinese mainland populations. The objective of this study is to investigate the association between the Thr241Met polymorphism in XRCC3 gene and risk of cancer for the Chinese Mainland populations by meta-analysis. We searched PubMed database, Embase database, CNKI database, and Wanfang database, and the last search was updated on July 24, 2013. Statistical analysis was performed using RevMan4.2 and Stata10.0 software. Finally, a total of 23 case-control studies in 23 articles were included. The results suggested a significant association between the Thr241Met polymorphism in XRCC3 gene and cancer risk in Chinese mainland populations (Met/Met + Thr/Met vs. Thr/Thr: OR = 1.25, 95 % CI = 1.02-1.54, P = 0.04). In the subgroup analyses by cancer types, significant associations were found in cervical cancer and nasopharyngeal cancer. The current meta-analysis suggested that the Thr241Met polymorphism in the XRCC3 gene may be a risk factor for cancer in Chinese mainland populations. In the future, more case-control studies are needed to validate these results.

Long-term impact of anaerobic reaction time on the performance and granular characteristics of granular denitrifying biological phosphorus removal systems.

Removal of nitrogen and phosphorus (P) from wastewater is successfully and widely practiced in systems employing both granular sludge technology and enhanced biological P removal (EBPR) processes; however, the key parameter, anaerobic reaction time (AnRT), has not been thoroughly investigated. Successful EBPR is highly dependent on an appropriate AnRT, which induces carbon and polyphosphate metabolism by phosphorus accumulating organisms (PAOs). Therefore, the long-term impact of AnRT on denitrifying P removal performance and granular characteristics was investigated in three identical granular sludge sequencing batch reactors with AnRTs of 90 (R1), 120 (R2) and 150 min (R3). The microbial community structures and anaerobic stoichiometric parameters related to various AnRTs were monitored over time. Free nitrite acid (FNA) accumulation (e.g., 0.0008-0.0016 mg HNO2-N/L) occurred frequently owing to incomplete denitrification in the adaptation period, especially in R3, which influenced the anaerobic/anoxic intracellular intermediate metabolites and activities of intracellular enzymes negatively, resulting in lower levels of poly-P and reduced activity of polyphosphate kinase. As a result, the Accumulibacter-PAOs population decreased from 51 ± 2.5% to 43 ± 2.1% when AnRT was extended from 90 to 150 min, leading to decreased denitrifying P removal performance. Additionally, frequent exposure of microorganisms to the FNA accumulation and anaerobic endogenous conditions in excess AnRT cases (e.g., 150 min) stimulated increased extracellular polymeric substances (EPS) production by microorganisms, resulting in enhanced granular formation and larger granules (size of 0.6-1.2 mm), but decreasing anaerobic PHA synthesis and glycogen hydrolysis. Phosphorus removal capacity was mediated to some extent by EPS adsorption in granular sludge systems that possessed more EPS, longer AnRT and relatively higher GAOs.

A comparison of endogenous processes during anaerobic starvation in anaerobic end sludge and aerobic end sludge from an anaerobic/anoxic/oxic sequencing batch reactor performing denitrifying phosphorus removal.

The endogenous processes in anaerobic end and aerobic end sludge responsible for biological denitrifying phosphorus removal were compared during a 7-d starvation under anaerobic conditions. The results showed that polyphosphate and glycogen were utilized simultaneously to generate maintenance energy for both the anaerobic and aerobic end sludge. During the 7-d starvation, the decay rate of denitrifying-phosphorus-accumulating-organisms (DPAOs) was higher for the aerobic end sludge than for the anaerobic end sludge. More energy was required for maintenance in the aerobic end sludge than for the anaerobic end sludge, with the greater amount of phosphorus release and glycogen degradation occurring in the aerobic end sludge. Moreover, different metabolic pathways for the endogenous processes were observed for the anaerobic and aerobic end sludge. After the 7-d starvation, the activity of DPAOs decreased more for the aerobic end sludge than that for the anaerobic end sludge.

The long-term effect of carbon source on the competition between polyphosphorus accumulating organisms and glycogen accumulating organism in a continuous plug-flow anaerobic/aerobic (A/O) process.

Laboratory experiments were conducted in a continuous plug-flow anaerobic/aerobic (A/O) process to kinetically investigate the long-term effect of the different carbon sources (i.e., acetate, acetate/propionate, propionate and glucose) on the competition between polyphosphorus accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). It was found that propionate was more benefit than acetate for PAOs even in the A/O process, and PAOs enriched with acetate were readily able to metabolize propionate without the requirement of adaptation. Glucose gave GAOs metabolic advantage in the PAOs-GAOs competition, which thereby worsened the EBPR performance. Nevertheless, the EBPR capacity could recover by returning carbon to acetate, with the acclimation time of approximately 2-SRTs. This suggests that the varying of carbon can be an effective approach to provide PAOs a competitive advantage over GAOs. Additionally, MLVSS/MLSS could indicate the shift of the microorganism between GAOs and PAOs, but it was not as precise as the biomass-P content.

[Characteristics and affecting factors of denitrifying phosphorus removal in two-sludge sequencing batch reactor].

The characteristics of denitrifying phosphorus removal in a lab-scale two-sludge anaerobic-anoxic/nitrification SBR (A2 NSBR) system were studied fed with domestic wastewater. The influence of some key operation parameters, like C/P, C/N, and HRT, were examined using parallel tests, pH, dissolved oxygen (DO) and redox potential (ORP) were monitored on line to validate whether they could be used as the control parameters for this denitrifying phosphorus removal process. Results indicated that P removal efficiency showed an increased trend on the whole with the increase of the C/P. When the influent C/P was greater than 19.39, good phosphorus removal efficiency was achieved. However, the phosphorus removal efficiency deteriorated once the influent C/P decreased less than 15.36. On the other hand, relatively good phosphorus removal efficiency could be maintained in the A2 NSBR system even at a low C/N ratio, though the denitrification efficiency decrease instead. It is also found that increasing the influent C/N increased the PHB amount stored by polyphosphate accumulating organisms (PAO) and therefore the ultimate denitrification and phosphorus removal efficiency were both improved. For an excessively high C/N, the incompletely reacted COD will be residual to anoxic stage. Thus, the pure denitrification reaction, which preferentially supports OHOs, becomes the dominant reaction. This decreases the amount of available electron acceptors for denitrifying polyphosphate accumulating organisms (DNPAOs) at the anoxic stage which eventually impacts the anoxic phosphorus removal capacity. In addition, since A2 NSBR has two completely independent SBR systems, it benefits to establish a process control system in terms of the parameters DO, ORP, and pH.