Improving water quality and mitigating CH4 and N2O production in urban landscape water simultaneously by optimizing calcium peroxide dosage.

Recent studies show that greenhouse gas (GHG) emissions from urban landscape water are significant and cannot be overlooked, underscoring the need to develop effective strategies for mitigating GHG production from global freshwater systems. Calcium peroxide (CaO2) is commonly used as an eco-friendly reagent for controlling eutrophication in water bodies, but whether CaO2 can reduce GHG emissions remains unclear. This study investigated the effects of CaO2 dosage on the production of methane (CH4) and nitrous oxide (N2O) in urban landscape water under anoxic conditions during summer. The findings reveal that CaO2 addition not only improved the physicochemical and organoleptic properties of simulated urban landscape water but also reduced N2O production by inhibiting the activity of denitrifying bacteria across various dosages. Moreover, CaO2 exhibited selective effects on methanogens. Specifically, the abundance of acetoclastic methanogen Methanosaeta and methylotrophic methanogen Candidatus_Methanofastidiosum increased whereas the abundance of the hydrogenotrophic methanogen Methanoregula decreased at low, medium, and high dosages, leading to higher CH4 production at increased CaO2 dosage. A comprehensive multi-objective evaluation indicated that an optimal dosage of 60 g CaO2/m2 achieved 41.21 % and 84.40 % reductions in CH4 and N2O production, respectively, over a 50-day period compared to the control. This paper not only introduces a novel approach for controlling the production of GHGs, such as CH4 and N2O, from urban landscape water but also suggests a methodology for optimizing CaO2 dosage, providing valuable insights for its practical application.

Hematochezia due to rectal invasion by an internal iliac artery aneurysm: A case report.

BACKGROUND: This case report presents the rare occurrence of hematochezia due to an internal iliac artery aneurysm leading to an arterioenteric fistula, expanding the differential diagnosis for gastrointestinal bleeding. It emphasizes the importance of considering vascular origins in cases of atypical hematochezia, particularly in the absence of common gastrointestinal causes, and highlights the role of imaging and multidisciplinary management in diagnosing and treating such unusual presentations. CASE SUMMARY: A 75-year-old man with a history of hypertension presented with 12 d of hematochezia, experiencing bloody stools 7-8 times per day. Initial computed tomography (CT) scans revealed an aneurysmal rupture near the right internal iliac artery with suspected hematoma development. Hemoglobin levels progressively decreased to 7 g/dL. Emergency arterial angiography and iliac artery-covered stent placement were performed, followed by balloon angioplasty. Despite initial stabilization, minor rectal bleeding and abdominal pain persisted, leading to further diagnostic colonoscopy. This identified a neoplasm and potential perforation at the proximal rectum. An exploratory laparotomy confirmed the presence of a hematoma and an aneurysm invading the rectal wall, necessitating partial rectal resection, intestinal anastomosis, and ileostomy. Postoperative recovery was successful, with no further bleeding incidents and normal follow-up CT and colonoscopy results after six months. CONCLUSION: In cases of unusual gastrointestinal bleeding, it is necessary to consider vascular causes for effective diagnosis and intervention.

Enhancing Oral Mucosal Barrier, Mitigating Microinflammation, and Addressing Malnutrition in Dialysis Patients: The Impact of Tangerine Peel Lemon Glycerin.

Objective: This study investigates the efficacy of tangerine peel lemon glycerin extract oral spray in improving oral mucosal barrier, reducing microinflammation, and addressing malnutrition in maintenance dialysis (MHD) patients. Methods: Tangerine peel and dry lemon underwent glycerin extraction. From January 2021 to June 2022, 72 MHD patients with thirst were prospectively chosen at Sinopharm Gezhouba Central Hospital. Randomization divided them into an observation group (n=36) and a control group (n=36). Both received routine maintenance dialysis and chronic kidney disease management. Oral conditions were assessed using OHIP-14, a homemade visual thirst score scale, SFR, sAA, and saliva pH. Microinflammatory indexes (CRP, TNF-α, IL-6) and nutritional status indicators (Alb, PA, Hb) were measured. The observation group used 1ml of tangerine peel lemon glycerin extract with a pH value of 5.9~6.1 q6h, while the control group used 1ml of purified water q6h. Results: After 3 months, the observation group showed significant improvement in OHIP-14 and visual thirst score scale (P < .01). Saliva pH, CRP, TNF-α, and IL-6 levels decreased, and SAA activity, SFR, Alb, PA, and Hb levels increased significantly in the observation group compared to the control group (P < .01). Conclusions: Tangerine peel lemon glycerin spray demonstrates promise in improving the oral mucosal barrier, exhibiting antibacterial and anti-inflammatory properties that mitigate microinflammation and malnutrition. This finding suggests a connection between oral health, systemic pathology, psychological state, and social adaptability.

Identification of arnicolide C as a novel chemosensitizer to suppress mTOR/E2F1/FANCD2 axis in non-small cell lung cancer.

BACKGROUND AND PURPOSE: The mammalian target of rapamycin (mTOR) pathway plays critical roles in intrinsic chemoresistance by regulating Fanconi anaemia complementation group D2 (FANCD2) expression. However, the mechanisms by which mTOR regulates FANCD2 expression and related inhibitors are not clearly elucidated. Extracts of Centipeda minima (C. minima) showed promising chemosensitizing effects by inhibiting FANCD2 activity. Here, we have aimed to identify the bioactive chemosensitizer in C. minima extracts and elucidate its underlying mechanism. EXPERIMENTAL APPROACH: The chemosensitizing effects of arnicolide C (ArC), a bioactive compound in C. minima, on non-small cell lung cancer (NSCLC) were investigated using immunoblotting, immunofluorescence, flow cytometry, the comet assay, small interfering RNA (siRNA) transfection and animal models. The online SynergyFinder software was used to determine the synergistic effects of ArC and chemotherapeutic drugs on NSCLC cells. KEY RESULTS: ArC had synergistic cytotoxic effects with DNA cross-linking drugs such as cisplatin and mitomycin C in NSCLC cells. ArC treatment markedly decreased FANCD2 expression in NSCLC cells, thus attenuating cisplatin-induced FANCD2 nuclear foci formation, leading to DNA damage and apoptosis. ArC inhibited the mTOR pathway and attenuated mTOR-mediated expression of E2F1, a critical transcription factor of FANCD2. Co-administration of ArC and cisplatin exerted synergistic anticancer effects in the A549 xenograft mouse model by suppressing mTOR/FANCD2 signalling in tumour tissues. CONCLUSION AND IMPLICATIONS: ArC suppressed DNA cross-linking drug-induced DNA damage response by inhibiting the mTOR/E2F1/FANCD2 signalling axis, serving as a chemosensitizing agent. This provides insight into the anticancer mechanisms of ArC and offers a potential combinatorial anticancer therapeutic strategy.

Rare synchronous colorectal carcinoma with three pathological subtypes: A case report and review of the literature.

BACKGROUND: Synchronous colorectal carcinomas (SCRC) are two or more primary colorectal carcinomas identified simultaneously or within 6 mo of the initial presentation in a single patient. Their incidence is low and the number of pathological types of SCRC is usually no more than two. It is very unusual that the pathological findings of a patient with SCRC show more than two different pathological subtypes. Here, we report a rare case of SCRC with three pathological subtypes. CASE SUMMARY: A 75-year-old woman who had no previous medical history or family history was admitted to the hospital because of intermittent hematochezia for more than a month. Colonoscopy displayed an irregularly shaped neoplasm of the rectum, a tumor-like lesion causing intestinal stenosis in the descending colon, and a polypoidal neoplasm in the ileocecum. Subsequently, she underwent total colectomy, abdominoperineal resection for rectal cancer, and ileostomy. After operation, the pathological report showed three pathological subtypes including well-differentiated adenocarcinoma of the ascending colon, moderately differentiated adenocarcinoma of the descending colon, and mucinous adenocarcinoma of the rectum. She is now recovering well and continues to be closely monitored during follow-up. CONCLUSION: Preoperative colonoscopy examination, imaging examination, and extensive intraoperative exploration play important roles in reducing the number of missed lesions.

Network pharmacology analysis combined with experimental validation to explore the therapeutic mechanism of salidroside on intestine ischemia reperfusion.

ETHNOPHARMACOLOGICAL RELEVANCE: Salidroside (SAL), a phenolic natural product present in Rhodiola rosea, are commonly used in the treatment of various ischemic-hypoxic diseases, including intestinal ischemia-reperfusion (IR) injury. However, their efficacy and potential mechanisms in the treatment of intestinal IR injury have not been investigated. OBJECTIVE: The objective of the present study is to investigate the pharmacological mechanism of action of SAL on intestinal IR injury using a network pharmacology approach combined with experimental validation. METHODS: In the present study, we used the Traditional Chinese Medicine Systematic Pharmacology (TCMSP) database and analysis platform and Comparative Toxicogenomics Database (CTD) to predict possible target genes of SAL, collected relevant target genes of intestinal IR injury from GeneCards and DisGenet websites, and collected summary data to screen common target genes. Then, the protein-protein interaction (PPI) target network was constructed and analyzed by STRING database and Cytoscape 3.8.2 with the above intersecting genes. Then, gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were performed and the component-target-pathway network was constructed, followed by the use of molecular docking and molecular dynamic simulation to verify the possible binding conformation between SAL and candidate targets to further explore the potential targets of SAL in the treatment of intestinal IR injury. Finally, an in vivo model of mouse superior mesenteric artery ligation was established to assess the anti-intestinal IR injury effect of SAL by assessing histopathological changes in mouse small intestine by HE staining, detecting inflammatory factor expression by ELISA kit, and detecting the expression of key protein targets by Western blotting. RESULTS: A total of 166 SAL target genes and 1740 disease-related targets were retrieved, and 88 overlapping proteins were obtained as potential therapeutic targets. The pathway enrichment analysis revealed that the pharmacological effects of SAL on intestinal IR injury were anti-hypoxic, anti-inflammatory and metabolic pathway related, and the molecular docking and molecular dynamic simulation results showed that the core bioactive components had good binding affinity for TXNIP and AMPK, and the immunoblotting results indicated that the expression levels of TXNIP and AMPK in the small intestinal tissues of mice in the drug-treated group compared with the model group were significantly changed. CONCLUSION: SAL may target AMPK and TXNIP domains to act as a therapeutic agent for intestinal IR. These findings comprehensively reveal the potential therapeutic targets for SAL against intestinal IR and provide theoretical basis for the clinical application of SAL in the treatment of intestinal IR.

Ethanol Extract of Citrus grandis 'Tomentosa' Exerts Anticancer Effects by Targeting Skp2/p27 Pathway in Non-Small Cell Lung Cancer.

SCOPE: This study aims to investigate the anticancer properties of Citrus grandis 'Tomentosa' (CGT) in non-small cell lung cancer (NSCLC). METHODS AND RESULTS: The ethanol extract of CGT (CGTE) is prepared by using anhydrous ethanol and analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), revealing that the main chemical components in CGTE are flavonoids and coumarins, such as naringin, rhoifolin, apigenin, bergaptol, and osthole. CGTE at concentrations without inducing cell death significantly inhibits cell proliferation via inducing cell cycle G1 phase arrest by MTT, colony formation, and flow cytometry assays, implying that CGT has anticancer potential. CGTE markedly inhibits the activity of Skp2-SCF E3 ubiquitin ligase, decreases the protein level of Skp2, and promotes the accumulation of p27 by co-immunoprecipitation (co-IP) and in vivo ubiquitination assay; whereas Skp2 overexpression rescues the effects of CGTE in NSCLC cells. In subcutaneous LLC allograft and A549 xenograft mouse models, CGTE, without causing obvious side effects in mice, significantly inhibits lung tumor growth by targeting the Skp2/p27 signaling pathway. CONCLUSION: These findings demonstrate that CGTE efficiently inhibits NSCLC proliferation both in vitro and in vivo by targeting the Skp2/p27 signaling pathway, suggesting that CGTE may serve as a therapeutic candidate for NSCLC treatment.

Role of Circular RNAs in Prostate Cancer.

OBJECTIVES: This study aims to summarize the current literature to demonstrate the importance of circular RNAs (circRNAs) in multiple aspects of prostate cancer (PCa) occurrence, progression, and treatment resistance and explore the potential role in therapeutic strategies aimed at targeting this molecule in PCa. METHODS: The relevant literature from PubMed and Medline databases is reviewed in this article. RESULTS: Non-coding RNA has been proven to play a vital role in regulating tumor progression. Among them, circular RNA plays a more unique role due to its nonlinear structure. Lots of circRNAs were found to be differentially expressed in PCa and regulate cell signaling pathways by regulating particular gene expressions. Recent studies have demonstrated that circRNAs are associated with the chemoresistance of urinary tumors, suggesting that circRNAs might be a novel therapeutic target and a marker for therapeutic response and prognosis assessment. CONCLUSION: The potential crosstalk of circRNAs modifications in PCa development, therapy, and regulation of tumor metabolism is portrayed in this review. However, more preclinical and clinical trials of this targeted strategy are necessary for the treatment of urinary tumors.

Molecular mechanism of tillering response to nitrogen in rice.

Nitrogen (N) fertilizer acts as the main driving force for agricultural productivity improvement. However, overuse of N fertilizer has caused severe effects to environment and ecosystem. Thus, it is pivotal to improve nitrogen use efficiency (NUE) for future sustainable agriculture. Agronomic traits response to N are significant indices for NUE phenotyping. For example, tiller number, grain number per panicle, and grain weight are three major components for cereal yields. Although regulatory mechanisms regarding to these three traits have been largely reported, few is known about how N affects them. Tiller number is one of the most sensitive traits response to N and also plays a key role for N-promoted yield improvement. It is thereby of great significance to dissect the genetic basis underlying tillering response to N. In this review, we summarize the factors contributing to NUE as well as the regulatory mechanisms over rice tillering and emphasize how N affects rice tillering, future research directions are also discussed for further improving NUE.

Flexible Metamaterial Quarter-Wave Plate and Its Application in Blocking the Backward Reflection of Terahertz Waves.

A terahertz flexible metamaterial quarter-wave plate (QWP) is designed and fabricated using polyimide as the substrate in this paper, with a 3 dB axial ratio bandwidth of 0.51 THz and high polarization conversion efficiency and transmittance. The effect of the incidence angle on the polarization conversion performance of the QWP is discussed by measuring the transmissions at multiple incidence angles. The blocking effect of this QWP combined with a polarizer on the backward reflection of terahertz waves is investigated by terahertz time-domain spectral transmission experiments. By adjusting the angle of the QWP and polarizer with respect to the incident light in the optical path, a blocking efficiency of 20 dB can be achieved at a 20° incidence angle, with a bandwidth of 0.25 THz, a maximum blocking efficiency of 58 dB at 1.73 THz, and an insertion loss of only 1.4 dB. Flexible terahertz metamaterial QWPs and polarizers can effectively block harmful reflected waves in terahertz communication and other systems. They have the advantages of a simple structure, ultra-thinness and flexibility, easy integration, no external magnetic field, and no low-temperature and other environmental requirements, thus having broad application prospects for terahertz on-chip integrated systems.

Promising anticancer activities and mechanisms of action of active compounds from the medicinal herb Centipeda minima (L.) A. Braun & Asch.

BACKGROUND: Centipeda minima (L.) A. Braun & Asch (C. minima) has been used as a traditional Chinese herbal medicine to treat multiple diseases, including sinusitis, rhinitis, headache, and allergy. To date, the anticancer properties of C. minima have drawn considerable attention owing to the anticancer potential of C. minima extracts, the identification of active components, and the elucidation of underlying molecular mechanisms. However, the anticancer properties and significance of active components in C. minima have rarely been summarized. PURPOSE: This review presents a comprehensive summary of the anticancer properties exhibited by active components of C. minima. METHODS: An extensive search for published articles on the anticancer activities and active components of C. minima was performed using Web of Science, PubMed, Science Direct, and Google Scholar. RESULTS: C. minima extracts exhibited both anticancer and chemosensitizing effects. Phytochemical studies have identified the active anticancer components of C. minima extracts. Sesquiterpene lactones, such as 6-O-angeloylplenolin (6-OAP, or brevilin A) and arnicolide D, have similar structures and anticancer mechanisms. As the most abundant sesquiterpene lactone in C. minima, 6-OAP exhibits anticancer activities mainly by targeting Skp1-Cullin1-F-box protein (SCF) E3 ubiquitin ligase and signal transducers and activators of transcription 3 (STAT3). Clinical trials have assessed the potential of 6-OAP in patients with vertex balding and alopecia areata, given its effect on JAK-STATs signaling. Chlorogenic acid, a representative organic acid in C. minima, reportedly possesses anticancer potential and inhibits tumor growth by affecting tumor microenvironment and has been approved for phase II clinical trials in patients with glioma in China. CONCLUSION: In the present review, we highlight intriguing anticancer properties mediated by active compounds isolated from C. minima extracts, particularly sesquiterpene lactones, which might provide clues for developing novel anticancer drugs. Relevant clinical trials on chlorogenic acid and 6-OAP can promote anticancer clinical applications. Therefore, it is worth comprehensively elucidating underlying anticancer mechanisms and conducting clinical trials on C. minima and its active components.

The crucial roles of long noncoding RNA SNHGs in lung cancer.

Lung cancer is one of the most common malignant tumors with growing morbidity and mortality worldwide. Several treatments are used to manage lung cancer, including surgery, radiotherapy and chemotherapy, as well as molecular-targeted therapy. However, the current measures are still far from satisfactory. Therefore, the current research should focus on exploring the molecular mechanism and then finding an effective treatment. Interestingly, we and others have embarked on a line of investigations focused on the mechanism of lung cancer. Specifically, lncRNA small nucleolar RNA host gene has been shown to be associated with biological characteristics and therapeutic resistance of lung cancer. In addition, small nucleolar RNA host genes may be used as diagnostic biomarker in the future. Herein, we will provide a brief review demonstrating the importance of small nucleolar RNA host genes in lung cancer, especially non-small cell lung cancer. Although lncRNA has shown a crucial role in tumor-related research, a large number of studies are needed to validate its clinical application in the future.

Lethal and sublethal effects of chlorantraniliprole on the migratory moths Agrotis ipsilon and A. segetum: New perspectives for pest management strategies.

BACKGROUND: Agrotis ipsilon and A. segetum are major migratory pests of many crops in China, and frequent regional outbreaks cause severe yield losses. Use of food attractants is one of the most promising control methods against adult lepidoptera, notably through the attract-and-kill strategy. Chlorantraniliprole's acute toxicity and sublethal effects on both moths were evaluated. RESULTS: Chlorantraniliprole showed high activity against both adults of both species, with LC20 and LC50 values of 0.08 and 0.21 mg L-1 (A. ipsilon), and 0.14 and 0.51 mg L-1 (A. segetum). The fecundity, effective oviposition rate, and egg hatching rate of both species in dual-sex exposure treatments were all significantly reduced compared with the control, and the population growth coefficients in the LC50 ♀ × LC50 ♂ treatments were only 0.32% (A. ipsilon) and 3.35% (A. segetum) that of the control. Furthermore, the flight distance was significantly suppressed from 6.67 km (control) to 0.01 km (LC50 ) for A. ipsilon, and from 7.39 km (control) to 0.78 km (LC50 ) for A. segetum. The proportions of robust- and medium-flight individuals of A. ipsilon and A. segetum in exposure treatments were greatly reduced. CONCLUSIONS: Low lethal concentration exposures to chlorantraniliprole can drastically reduce the reproduction and flight performance of A. ipsilon and A. segetum, while inhibiting the production of offspring, suggesting chlorantraniliprole would be an excellent compound for use in combination with food attractants. Chlorantraniliprole has good potential for management of the two long-range migratory pests tested using an attract-and-kill strategy. © 2022 Society of Chemical Industry.

Dispersion Theory of Surface Plasmon Polaritons on Bilayer Graphene Metasurfaces.

Surface plasmon polaritons (SPPs) on the graphene metasurfaces (GSPs) are crucial to develop a series of novel functional devices that can merge the well-established plasmonics and novel nanomaterials. Dispersion theory on GSPs is an important aspect, which can provide a basic understanding of propagating waves and further guidance for potential applications based on graphene metamaterials. In this paper, the dispersion theory and its modal characteristics of GSPs on double-layer graphene metasurfaces consisting of the same upper and lower graphene micro-ribbon arrays deposited on the dielectric medium are presented. In order to obtain its dispersion expressions of GSP mode on the structure, an analytical approach is provided by directly solving the Maxwell's equations in each region and then applying periodical conductivity boundary onto the double interfaces. The obtained dispersion expressions show that GSPs split into two newly symmetric and antisymmetric modes compared to that on the single graphene metasurface. Further, the resultant dispersion relation and its propagating properties as a function of some important physical parameters, such as spacer, ribbon width, and substrate, are treated and investigated in the Terahertz band, signifying great potentials in constructing various novel graphene-based plasmonic devices, such as deeply sub-wavelength waveguides, lenses, sensors, emitters, etc.

Local pressure calibration method of inductively coupled plasma generator based on laser Thomson scattering measurement.

Based on laser Thomson scattering (TS) measurements and finite element method (FEM) simulations of electron density in inductively coupled plasma (ICP), the simulated local pressure calibration curves of ICP generator are obtained by comparing the experimental and simulated electron density distributions and maxima. The equation coefficients of theoretical model associated with the ICP generator experimental system can be obtained by fitting the simulation curve with the least square method, and the theoretical pressure calibration curves under different absorbed powers can be further obtained. Combined with the vacuum gauge measurements, both the simulated and theoretical pressure calibration curves can give the true local pressure in the plasma. The results of the local pressure calibration at the different absorbed powers show that the density gradient from the vacuum gauge sensor to the center of the coil in ICP generator cavity becomes larger with the increase of electron density, resulting in a larger gap between the measured value and the pressure calibration value. This calibration method helps to grasp the local pressure of ICP as an external control factor and helps to study the physicochemical mechanism of ICP in order to achieve higher performance in ICP etching, material modification, etc.

Brusatol has therapeutic efficacy in non-small cell lung cancer by targeting Skp1 to inhibit cancer growth and metastasis.

Skp1-Cul1-F-box protein (SCF) ubiquitin E3 ligases play important roles in cancer development and serve as a promising therapeutic target in cancer therapy. Brusatol (Bru), a known Nrf2 inhibitor, holds promise for treating a wide range of tumors; however, the direct targets of Bru and its anticancer mode of action remain unclear. In our study, 793 Bru-binding candidate proteins were identified by using a biotin-brusatol conjugate (Bio-Bru) followed by streptavidin-affinity pull down-based mass spectrometry. We found that Bru can directly bind to Skp1 and disrupt the interactions of Skp1 with the F-box protein Skp2, leading to the inhibition of the Skp2-SCF E3 ligase. Bru inhibited both proliferation and migration via promoting the accumulation of the substrates p27 and E-cadherin; Skp1 overexpression attenuated while Skp1 knockdown enhanced these effects of Bru in non-small cell lung cancer (NSCLC) cells. Moreover, Bru binding to Skp1 also inhibited the ß-TRCP-SCF E3 ligase. In both subcutaneous and orthotopic NSCLC xenografts, Bru significantly inhibited the growth and metastasis of NSCLC through targeting SCF complex and upregulating p27 and E-cadherin protein levels. These data demonstrate that Bru is a Skp1-targeting agent that may have therapeutic potentials in lung cancer.

Fouling and cleaning of thin film composite forward osmosis membrane treating municipal wastewater for resource recovery.

Concentrating municipal wastewater by forward osmosis (FO) membrane to a high level of water recovery rate to facilitate downstream resource recovery might cause more serious membrane fouling. This study investigated the concentration of synthetic and real municipal wastewater to 90% water recovery rate by hollow fiber and flat-sheet thin film composite (TFC) FO membranes and their associated membrane fouling and cleaning. Results show that the FO membrane had high rejection rates of COD, phosphate, Ca2+ and Mg2+ with concentration factors at around 8 when achieving a 90% water recovery rate, which facilitated downstream phosphate recovery by precipitation and energy recovery by anaerobic digestion. Ca2+ concentration in municipal wastewater at 61 mg/L was found to be the main factor to cause inorganic scaling, and the fouling caused by calcium precipitates was harder to be cleaned by physical cleaning compared with suspended solids (SS) such as cellulose particles. In addition, the TFC FO membrane for treating real sewage with SS is not applicable for the hollow fiber configuration used in this study due to lumen clogging, while the TFC flat sheet configuration was able to achieve a 90% water recovery rate. The use of a spacer in the flat sheet configuration improved the efficiency of the following physical cleaning by around 15% although it did not alleviate membrane fouling during the membrane filtration process. This study highlighted the importance of the chemistry of FS and DS and FO membrane configuration on membrane fouling particularly at high water recovery rates and the necessity of pre-treatment of municipal wastewater by removing suspended solids.

Exploration of mechanisms for calcium phosphate precipitation and accumulation in nitrifying granules by investigating the size effects of granules.

Calcium phosphate could be accumulated in aerobic granules, which attracts attention recently for phosphorus removal and recovery from wastewater. In this study, partial nitrifying granules with high calcium precipitate content were sorted into different size groups for characterization and evaluation to reveal the dynamic balance of granules at stead state and relevant calcium phosphate precipitation and accumulation mechanism. It was found that light yellow small granules without calcium precipitates but high microbial activity co-existed with deep brown granules with calcium precipitate of around 91% and low microbial activity. Characterization with specific oxygen uptake rates, specific ammonium oxidation rates, calcium and phosphate removal rates from solution, EPS contents, elemental compositions by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and scanning electron microscopy (SEM) for different size groups of granules enabled a proposal of a new hypothesized mechanism for calcium precipitation and accumulation. With this proposed mechanism, it is believed that sufficient granule retention time in reactors was critical for the accumulation of calcium precipitates followed by a slow microbial growth rate of biomass due to mass transfer resistance. The co-precipitation of calcium carbonate and calcium phosphate mainly occurred in granules with a size less than 710 µm while calcium phosphate dominant minerals were accumulated in granules larger than 710 µm. The results and conclusions in this study shed light on the mechanisms of calcium phosphate accumulation in granules, which could be used to better operate and control aerobic granular sludge with calcium phosphates for phosphorus removal and recovery.