Clinical Significance of Thyroid Autoantibodies in Differential Diagnosis and Predicting the Course of Programmed Cell Death Protein-1 Inhibitor-Induced Thyroid Dysfunction.

OBJECTIVE: Thyroid immune-related thyrotoxicosis is one of the most common adverse effects in patients treated with programmed cell death protein-1 (PD-1) inhibitors. We investigated the significance of levels of serum anti-thyroglobulin antibodies (TgAbs), anti-thyroid peroxidase antibodies (TPOAbs), and thyroid-stimulating hormone receptor antibodies (TRAbs) in the identification of anti-PD-1-induced thyroid thyrotoxicosis. METHODS: We divided 161 patients with thyroid dysfunction who received PD-1 inhibitors at our hospital between January 2022 and June 2024 into 3 groups: primary hypothyroidism group, primary hyperthyroidism group, and destructive thyroiditis group. The characteristics of the 3 groups were determined, and the positivity rates of serum TgAbs, TPOAbs, and TRAbs were assessed. An additional 42 patients diagnosed with Hashimoto's thyroiditis were selected as the control group for PD-1 inhibition-induced destructive thyroiditis. Age, sex, and time of transition from thyrotoxicosis to hypothyroidism in the 2 groups were compared. RESULTS: In the primary hypothyroidism group, only 1 case was TPOAbs-positive (1/1%). In the destructive thyroiditis group, the positivity rate for TPOAbs or TgAbs was 92.9%, and TPOAbs and TgAbs were negative in the primary hyperthyroidism group. TRAbs were undetectable in all 3 groups. There were statistically significant differences in age, sex, and time from thyrotoxicosis to hypothyroidism in the PD-1 induced destructive thyroiditis and Hashimoto's thyroiditis groups. CONCLUSIONS: In patients with thyrotoxicosis caused by PD-1 inhibitors, serum TgAb, and TPOAb levels can be used to distinguish between primary hyperthyroidism and destructive thyroiditis. This study provides insights into novel treatment targets and effective management strategies for PD-1-induced thyrotoxicosis.

Numerical model for electrogenic transport by the ATP-dependent potassium pump KdpFABC.

In vitro assays of ion transport are an essential tool for understanding molecular mechanisms associated with ATP-dependent pumps. Because ion transport is generally electrogenic, principles of electrophysiology are applicable, but conventional tools like patch-clamp are ineffective due to relatively low turnover rates of the pumps. Instead, assays have been developed to measure either voltage or current generated by transport activity of a population of molecules either in cell-derived membrane fragments or after reconstituting purified protein into proteoliposomes. In order to understand the nuances of these assays and to characterize effects of various operational parameters, we have developed a numerical model to simulate data produced by two relevant assays: fluorescence from voltage-sensitive dyes and current recorded by capacitive coupling on solid supported membranes. Parameters of the model, which has been implemented in Python, are described along with underlying principles of the computational algorithm. Experimental data from KdpFABC, a K+ pump associated with P-type ATPases, are presented, and model parameters have been adjusted to mimic these data. In addition, effects of key parameters such as nonselective leak conductance and turnover rate are demonstrated. Finally, simulated data are used to illustrate the effects of capacitive coupling on measured current and to compare alternative methods for quantification of raw data.

Energy coupling and stoichiometry of Zn2+/H+ antiport by the prokaryotic cation diffusion facilitator YiiP.

YiiP from Shewanella oneidensis is a prokaryotic Zn2+/H+ antiporter that serves as a model for the Cation Diffusion Facilitator (CDF) superfamily, members of which are generally responsible for homeostasis of transition metal ions. Previous studies of YiiP as well as related CDF transporters have established a homodimeric architecture and the presence of three distinct Zn2+ binding sites named A, B, and C. In this study, we use cryo-EM, microscale thermophoresis and molecular dynamics simulations to address the structural and functional roles of individual sites as well as the interplay between Zn2+ binding and protonation. Structural studies indicate that site C in the cytoplasmic domain is primarily responsible for stabilizing the dimer and that site B at the cytoplasmic membrane surface controls the structural transition from an inward facing conformation to an occluded conformation. Binding data show that intramembrane site A, which is directly responsible for transport, has a dramatic pH dependence consistent with coupling to the proton motive force. A comprehensive thermodynamic model encompassing Zn2+ binding and protonation states of individual residues indicates a transport stoichiometry of 1 Zn2+ to 2-3 H+ depending on the external pH. This stoichiometry would be favorable in a physiological context, allowing the cell to use the proton gradient as well as the membrane potential to drive the export of Zn2+.

Energy Coupling and Stoichiometry of Zn2+/H+ Antiport by the Cation Diffusion Facilitator YiiP.

YiiP is a prokaryotic Zn2+/H+ antiporter that serves as a model for the Cation Diffusion Facilitator (CDF) superfamily, members of which are generally responsible for homeostasis of transition metal ions. Previous studies of YiiP as well as related CDF transporters have established a homodimeric architecture and the presence of three distinct Zn2+ binding sites named A, B, and C. In this study, we use cryo-EM, microscale thermophoresis and molecular dynamics simulations to address the structural and functional roles of individual sites as well as the interplay between Zn2+ binding and protonation. Structural studies indicate that site C in the cytoplasmic domain is primarily responsible for stabilizing the dimer and that site B at the cytoplasmic membrane surface controls the structural transition from an inward facing conformation to an occluded conformation. Binding data show that intramembrane site A, which is directly responsible for transport, has a dramatic pH dependence consistent with coupling to the proton motive force. A comprehensive thermodynamic model encompassing Zn2+ binding and protonation states of individual residues indicates a transport stoichiometry of 1 Zn2+ to 2-3 H+ depending on the external pH. This stoichiometry would be favorable in a physiological context, allowing the cell to use the proton gradient as well as the membrane potential to drive the export of Zn2+.

Enhanced H2O2 utilization efficiency in Fenton-like system for degradation of emerging contaminants: Oxygen vacancy-mediated activation of O2.

Hydrogen peroxide (H2O2) is the most commonly used oxidant in advanced oxidation processes for emerging organic contaminant degradation. However, the activation of H2O2 to generate reactive oxygen species is always accompanied by O2 generation resulting in H2O2 waste. Here, we prepare a Ti doped Mn3O4/Fe3O4 ternary catalyst (Ti-Mn3O4/Fe3O4) to create abundant oxygen vacancies (OVs), which yields electron delocalization impacts on enhancing the electrical conductivity, accelerating the activation of O2 to produce H2O2. In Ti-Mn3O4/Fe3O4/H2O2 system, OVs-mediated O2/O2•-/H2O2 redox cycles trigger the activation of locally generated O2, boost the regeneration of O2•- and on site produce H2O2 for replenishment. This leads to a 100% removal of tiamulin in 30 min at an unprecedented H2O2 utilization efficiency of 96.0%, which is 24 folds higher than that with Fe3O4/H2O2. Importantly, further integration of Ti-Mn3O4/Fe3O4 catalysts into membrane filtration achieved high rejections of tiamulin (> 83.9%) from real surface water during a continuous 12-h operation, demonstrating broad pH adaptability, excellent catalytic stability and leaching resistance. This work demonstrates a feasible strategy for developing OVs-rich catalysts for improving H2O2 utilization efficiency via activation of locally generated oxygen during the Haber-Weiss reaction.

Peroxymonosulfate activated by composite ceramic membrane for the removal of pharmaceuticals and personal care products (PPCPs) mixture: Insights of catalytic and noncatalytic oxidation.

A composite manganese-based catalytic ceramic membrane (Mn-CCM) was developed by a solid-state sintering method, and its effectiveness toward activation of peroxymonosulfate (PMS) for the degradation of 11 pharmaceutical and personal care products (PPCPs) mixture was tested. The optimized Mn-CCMs/PMS system showed remarkable degradation efficiencies for PPCPs mixture with total removal >90% in ultrapure water, river water and natural organic matter (NOM) solution. The Mn-CCMs/PMS system showed the contribution of different phenomena in PPCPs removal in the order of catalytic oxidation (54.7%, Mn-CCMs/PMS) > noncatalytic oxidation (42.3%, PMS oxidation) > adsorption (3.0%, by Mn-CCMs). The singlet oxygen (1O2) was the dominant reactive oxygen specie for the degradation of PPCPs in all water matrices proved by the quenching experiments and electro-paramagnetic resonance (EPR) spectroscopy. The extraordinary stability of Mn-CCMs for the activation of PMS has been noted in terms of repeatability experiments for PPCPs degradation with fewer leaching of Mn (1.9 to 3.6 µg/L). Mineralization was achieved in the range of 28-65% for different water matrices. The toxicity of the PPCPs mixture was reduced by 85.9%. The Mn-CCMs/PMS system showed a reduction (25-100%) in precursors of different carbon- and nitrogen-based disinfection by-products. This study found the Mn-CCMs/PMS system as a feasible purification unit for removing trace concentrations of PPCPs (ng/L) in real drinking water matrices.

Unraveling dissolved organic matter in drinking water through integrated ozonation/ceramic membrane and biological activated carbon process using FT-ICR MS.

The performance of an integrated process comprising coagulation, ozonation, and catalytic ceramic membrane filtration (CMF) followed by treatment with biological active carbon (BAC) was evaluated in a pilot-scale (96 m3/d) experiment to understand the biostability and quality of the finished water. The fate of dissolved organic matter (DOM) at the molecular level was explored using Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Biostable finished water with an assimilable organic carbon (AOC) concentration of 30.2-45.4 µg/L was obtained by the integrated process, and the high hydraulic retention time (HRT) (≥ 45 min) of the BAC filter was necessary to provide biostable finished water. The coagulation/O3/CMF unit efficiently transformed nitrogen-containing polyaromatic hydrocarbons (PAH) with aromaticity and large molecular weight (Mw) (500-1000 Da) into CHO-type highly unsaturated phenolic compounds (HuPh) with less aromaticity and medium Mw (300-500 Da), which were effectively removed by subsequent BAC filtering. The main reaction was oxygen addition, followed by deamination and dealkylation of the coagulation/O3/CMF unit and decarboxylation of the BAC filter. Principal component analysis revealed that N-containing and large-Mw PAH are potential AOC precursors, and the chemical characteristics of CHO-type and medium-Mw HuPh make them AOC candidates (correlation coefficients > 0.96). This study provides insights into the management of drinking water biostability and its suitability for the practical application of the integrated coagulation/O3/CMF-BAC process in drinking water treatment plants.

Analysis of Relevant Factors Affecting the Pregnancy Rate of Frozen-Thawed Embryo Transfer Cycle.

Objective: The aim of this study is to explore the relevant factors affecting the pregnancy rate of frozen-thawed embryo transfer cycle. Methods: The clinical data of 931 patients who underwent artificial cycle preparation for endometrial FET from April 2017 to November 2020 in the reproductive center of our hospital were retrospectively analyzed. Results: According to the pregnancy situation, the patients were divided into 450 cases of pregnancy and 481 cases of biochemical pregnancy. The univariate analysis of FET biochemical pregnancy showed that there were statistically significant differences between pregnancy and biochemical pregnancy in terms of years of infertility, age, endometrial thickness, P level, E2/P, and the number of high-quality embryos (P < 0.05). Multivariate analysis of pregnancy showed that age <30 years was a protective factor for biochemical pregnancy and endometrial thickness <8 mm and E2/P < 0.3 were risk factors (P < 0.05). Conclusion: The regulation of endometrial thickness and E2/P serves as the key of treatment for patients undergoing FET using artificial cycle preparation for endometrial transfer, and it contributes to improve the pregnancy rate; also, the patient's age is an important indicator influencing the pregnancy rate.

Ceramic nanofiber membrane anchoring nanosized Mn2O3 catalytic ozonation of sulfamethoxazole in water.

Catalytic ceramic nanofiber membranes (Mn@CNMs) were prepared by anchoring Mn2O3 nanoparticles on the pits of attapulgite (APT) nanofibers via an impregnation and in-situ precipitation method. An integrated catalytic ozonation/membrane filtration process applying Mn@CNM was employed to degrade sulfamethoxazole (SMX) and the removal achieved up to 81.3% during a 7-h continuous filtration. The reactive oxygen species (ROS) quenching and radical detection experiments were conducted to determine the contribution of 1O2, ·OH and O2·- towards the catalytic degradation of SMX. Moreover, Mn@CNM exhibited wide applicability for real water matrix and the total removal of various kinds of emerging contaminants in real hospital wastewater reached up to 98.5%. The excellent performances of Mn@CNM were attributed to the nano-confinement effect in the membrane layer. First, anchoring Mn2O3 nanoparticles on the pits of the APT surface suppressed the growth and aggregation of nanosized Mn2O3, providing abundant reactive sites for catalytic ozonation. Second, the interlaced APT nanofibers formed nano-sized network structures, where ROS and SMX were confined in close vicinity and ROS have more chances to attack SMX. This work provides a promising strategy for the preparation of catalytic ceramic membrane with high catalytic efficiency for degradation of emerging contaminants in water.

Integration of coagulation and ozonation with flat-sheet ceramic membrane filtration for shale gas hydraulic fracturing wastewater treatment: A laboratory study.

The performance of the integrated process of coagulation and ozonation with ceramic membrane filtration was evaluated for the treatment of shale gas hydraulic fracturing flowback wastewater (HFFW). The removal efficiencies of carbon oxygen demand (CODCr ), dissolved organic carbon (DOC), petroleum oils, and turbidity in effluent by the combined process were 87.1%, 72.2%, 94.3%, and 99.6%, respectively. Compared with sole membrane filtration, the transmembrane pressure (TMP) of ceramic membrane filtration was reduced by >99% with the integrated process. The coagulation and ozonation can effectively remove the organics with high molecular weights in the cake layer of ceramic membrane. To the best of our knowledge, this work proposed the combined process of coagulation, ozonation, and flat-sheet ceramic membrane filtration for the treatment of HFFW for the first time. The water quality of the effluent met the discharge standard (Comprehensive Wastewater Discharge Standard GB8978-1996). The findings can provide an important technical foundation for the innovation of integrated equipment for HFFW treatment. PRACTITIONER POINTS: An integrated process combining coagulation and ozonation with flat-sheet ceramic membrane ultrafiltration for the treatment of shale gas wastewater. The water quality of this integrated process met the discharge standard. Coagulation and ozonation effectively alleviated the membrane fouling related to organics with high molecular weights. A new avenue for on-site treatment of shale gas wastewater and an alternative of the current centralized wastewater management.

Structural basis for potassium transport in prokaryotes by KdpFABC.

KdpFABC is an oligomeric K+ transport complex in prokaryotes that maintains ionic homeostasis under stress conditions. The complex comprises a channel-like subunit (KdpA) from the superfamily of K+ transporters and a pump-like subunit (KdpB) from the superfamily of P-type ATPases. Recent structural work has defined the architecture and generated contradictory hypotheses for the transport mechanism. Here, we use substrate analogs to stabilize four key intermediates in the reaction cycle and determine the corresponding structures by cryogenic electron microscopy. We find that KdpB undergoes conformational changes consistent with other representatives from the P-type superfamily, whereas KdpA, KdpC, and KdpF remain static. We observe a series of spherical densities that we assign as K+ or water and which define a pathway for K+ transport. This pathway runs through an intramembrane tunnel in KdpA and delivers ions to sites in the membrane domain of KdpB. Our structures suggest a mechanism where ATP hydrolysis is coupled to K+ transfer between alternative sites in KdpB, ultimately reaching a low-affinity site where a water-filled pathway allows release of K+ to the cytoplasm.

In-Situ H2O2 Cleaning for Fouling Control of Manganese-Doped Ceramic Membrane through Confined Catalytic Oxidation Inside Membrane.

This work presents an effective approach for manganese-doped Al2O3 ceramic membrane (Mn-doped membrane) fouling control by in-situ confined H2O2 cleaning in wastewater treatment. An Mn-doped membrane with 0.7 atomic percent Mn doping in the membrane layer was used in a membrane bioreactor with the aim to improve the catalytic activity toward oxidation of foulants by H2O2. Backwashing with 1 mM H2O2 solution at a flux of 120 L/m2/h (LMH) for 1 min was determined to be the optimal mode for in-situ H2O2 cleaning, with confined H2O2 decomposition inside the membrane. The Mn-doped membrane with in-situ H2O2 cleaning demonstrated much better fouling mitigation efficiency than a pristine Al2O3 ceramic membrane (pristine membrane). With in-situ H2O2 cleaning, the transmembrane pressure increase (ΔTMP) of the Mn-doped membrane was 22.2 kPa after 24-h filtration, which was 40.5% lower than that of the pristine membrane (37.3 kPa). The enhanced fouling mitigation was attributed to Mn doping, in the Mn-doped membrane layer, that improved the membrane surface properties and confined the catalytic oxidation of foulants by H2O2 inside the membrane. Mn3+/Mn4+ redox couples in the Mn-doped membrane catalyzed H2O2 decomposition continuously to generate reactive oxygen species (ROS) (i.e., HO• and O21), which were likely to be confined in membrane pores and efficiently degraded organic foulants.

Ceramic membrane based hybrid process for the upgrade of rural water treatment plants: A pilot study.

An integrated process with ozonation, ceramic membrane ultrafiltration, and activated carbon filtration is investigated for the treatment of drinking water in the rural area of China. A pilot-scale experiment with a capacity of 20 m3 /d is conducted, and a number of water quality parameters are evaluated, such as turbidity, color, organic matter (CODMn ), manganese (Mn), geosmin (GSM), 2-methylisoborneol (2-MIB), and 37 kinds of pharmaceutical and personal care products (PPCPs). The result shows that the removal efficiency of all the evaluated parameters of this integrated process is much higher than that of the conventional treatment processes. In particular, the removal rate of PPCPs achieves 52.5%, which is twice higher than that of the conventional process. Moreover, ozone can oxidize manganese ions, degrade organic matters, and reduce membrane fouling. It is believed that the integrated treatment process developed in this study is efficient in upgrading the existing water treatment plants and ensuring the safety of drinking water in the rural areas around the world.

Emerging organic contaminants and odorous compounds in secondary effluent wastewater: Identification and advanced treatment.

This study aims to address organic micropollutants in secondary effluents from municipal wastewater treatment plants (WWTPs) by first identification of micropollutants in different treatment units, and second by evaluating an advanced treatment process for removals of micropollutants. In secondary effluents, 28 types of pharmaceutical and personal care products (PPCPs), 5 types of endocrine disrupting chemicals (EDCs) and 3 types of odorous compounds are detected with total concentrations of 513 ± 57.8 ng/L, 991 ± 36.5 ng/L, 553 ± 48.3 ng/L, respectively. An integrated process consisting of in-situ ozonation, ceramic membrane filtration (CMF) and biological active carbon (BAC) filtration is investigated in a pilot scale (1000 m3/d) for removal of micropollutants in secondary effluents. The total removal efficiencies of PPCPs, EDCs and odorous compounds are 98.5%, 95.4%, and 91.1%, respectively. Removal mechanisms of emerging organic contaminants (EOCs) and odorous compounds are discussed based on their physicochemical properties. The remarkable removal efficiencies of micropollutants by the pilot system is attributed to synergistic effects of combining ozonation, ceramic membrane filtration and BAC filtration. This study provides a cost-effective and robust technology with the capability of treating secondary effluents for reuse applications.

Elucidating the impacts of intermittent in-situ ozonation in a ceramic membrane bioreactor: Micropollutant removal, microbial community evolution and fouling mechanisms.

In this study, impacts of in-situ ozonation applied directly in the membrane tank of a ceramic MBR (Oz-MBR) were assessed to elucidate its implications on micropollutant removal, microbial taxa and membrane fouling. The basic effluent quality (i.e., bulk organics and nutrients) of the MBR without and with in-situ ozonation was comparable. Importantly, pollutant-specific (10-26%) improvement in micropollutant removal was achieved by the Oz-MBR, which could be attributed to the increase in the abundance of microbial taxa responsible for the removal of structurally complex pollutants and/or ozone-assisted oxidation. In-situ ozonation affected the abundance of denitrifying bacteria and functional genes but total nitrogen removal by the Oz-MBR was comparable to that achieved by the control (C)-MBR. Improved mixed liquor properties, and the reduced accumulation of foulants on the membrane surface resulted in membrane fouling alleviation (53%) in the Oz-MBR. In addition, fouling models evaluated for the first time in the case of Oz-MBR indicated that the cake-complete model was suitable to explain membrane fouling mechanism. This comprehensive study demonstrates the performance of MBR coupled with in-situ ozonation, and the obtained results would serve as a useful reference for its implementation at pilot- and/or full-scale.

Serine phosphorylation regulates the P-type potassium pump KdpFABC.

KdpFABC is an ATP-dependent K+ pump that ensures bacterial survival in K+-deficient environments. Whereas transcriptional activation of kdpFABC expression is well studied, a mechanism for down-regulation when K+ levels are restored has not been described. Here, we show that KdpFABC is inhibited when cells return to a K+-rich environment. The mechanism of inhibition involves phosphorylation of Ser162 on KdpB, which can be reversed in vitro by treatment with serine phosphatase. Mutating Ser162 to Alanine produces constitutive activity, whereas the phosphomimetic Ser162Asp mutation inactivates the pump. Analyses of the transport cycle show that serine phosphorylation abolishes the K+-dependence of ATP hydrolysis and blocks the catalytic cycle after formation of the aspartyl phosphate intermediate (E1~P). This regulatory mechanism is unique amongst P-type pumps and this study furthers our understanding of how bacteria control potassium homeostasis to maintain cell volume and osmotic potential.

Long noncoding RNA HULC in acute ischemic stroke: Association with disease risk, severity, and recurrence-free survival and relation with IL-6, ICAM1, miR-9, and miR-195.

BACKGROUND: This study aimed to evaluate the clinical role of long noncoding RNA (lncRNA) HULC in acute ischemic stroke (AIS). METHODS: LncRNA HULC in plasma samples from 215 first episode AIS patients and 215 age/gender-matched non-AIS controls was detected by reverse transcriptional-quantitative polymerase chain reaction (RT-qPCR). Then, in AIS patients, interleukin-6 and intercellular adhesion molecule 1 (ICAM1), as well as microRNA (miR) target of lncRNA HUCL (miR-9 and miR-195), were detected by enzyme-linked immunosorbent assay and RT-qPCR, respectively. Disease severity was assessed by National Institution of Health stroke scale (NIHSS) score. AIS recurrence or death was recorded, and recurrence-free survival (RFS) was calculated. RESULTS: LncRNA HULC was increased in AIS patients compared to non-AIS controls (P < .001), and receiver operating characteristic curve showed that it was correlated with increased AIS risk (area under curve: 0.876, 95% confidence interval: 0.843-0.908). Meanwhile, lncRNA HULC was positively correlated with NIHSS score (P < .001, r = .456), interleukin-6 (P < .001, r = .275) and ICAM1 (P < .001, r = .383), whereas negatively correlated with miR-9 (P < .001, r = -.438) but not miR-195 (P = .205, r = -.087) in AIS patients. Additionally, miR-9 was negatively correlated with NIHSS score (P < .001, r = -.335), interleukin-6 (P = .001, r = -.231), and ICAM1 (P < .001, r = -.280), while miR-195 was only negatively associated with NIHSS score (P = .041, r = -.139) in AIS patients. Moreover, lncRNA HULC high expression predicted worse RFS (P = .013) in AIS patients. CONCLUSION: LncRNA HULC is correlated with higher AIS risk, increased disease severity and worse prognosis in AIS patients. Meanwhile, it associates with higher IL-6, elevated ICAM1, and lower miR-9 AIS patients.

Powdered activated carbon - Membrane bioreactor (PAC-MBR): Impacts of high PAC concentration on micropollutant removal and microbial communities.

In this study, the effect of a high concentration of powdered activated carbon (PAC) on pollutant removal and microbial communities was systematically investigated. Micropollutant removal by the 'control' MBR (without PAC addition) was pollutant-specific and was mainly controlled by their molecular properties. The PAC-MBR achieved enhanced removal of micropollutant by 10% (ofloxacin) to 40% (caffeine). Analysis of the microbial communities in the sludge samples collected from both MBRs indicated an increase in the abundance of 24 (out of 31) genera following PAC addition. Notably, bacterial diversity enriched, particularly in the anoxic zone of the PAC-MBR, indicating a positive impact of recirculating mixed liquor containing PAC from the aerobic to the anoxic zone. In addition, PAC improved the abundance of Comamonas and Methanomethylovorans (up to 2.5%) that can degrade recalcitrant micropollutants. According to the quantitative PCR (qPCR) analysis, the copies of functional genes (nirS, nosZ and narG) increased in PAC-MBR. This study demonstrated that MBR could be operated at a high PAC concentration without compromising the pollutant removal and microbial community evolution during wastewater treatment.

Seasonal occurrence of N-nitrosamines and their association with dissolved organic matter in full-scale drinking water systems: Determination by LC-MS and EEM-PARAFAC.

N-nitrosamines have been identified as emerging contaminants with tremendous carcinogenic potential for human beings. This study examined the seasonal changes in the occurrence of N-nitrosamines and N-nitrosodimethylamine formation potential (NDMA-FP) in drinking water resources and potable water from 10 drinking water treatment plants in a southern city of China. The changes in N-nitrosamines are well correlated with dissolved organic matter (DOM), particularly fluorophores, which were measured and compared between traditional fluorescence indices and excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Four of N-nitrosamine species including N-nitrosodimethylamine (NDMA), N-Nitrosodibutylamine (NDBA), N-Nitrosopyrrolidine (NPYR), and N-Nitrosodiphenylamine (NDPhA) are found to be abundant compounds with an average of 29.5% (26.7%), 20.0% (25.2%), 18.9% (16.0%), and 9.0% (9.9%) in the source (and treated) water, respectively. The sum of N-nitrosamines concentration is recorded to be low in the wet season (July-September), whereas the dry season (October-December) provided opposite impacts. EEM-PARAFAC modeling indicated the predominance of humic-like component (C1) in the wet season while in the dry season the water was dominant in protein-like component (C2). All the N-nitrosamines excluding NDPhA and N-Nitrosomorpholine (NMOR) showed a strong association with protein-like component (C2). In contrast, humic-like C1, which was directly influenced by rainfall, was found to be a suitable proxy for NMOR and NDPhA. The results of this study are valuable to understand the correlation between different N-nitrosamines and DOM through adopting fluorescence signatures.

An integrated process for the advanced treatment of hypersaline petrochemical wastewater: A pilot study.

An integrated process combining ozonation, ceramic membrane filtration with biological activated carbon filtration (O3+CMF + BAC process) was designed and evaluated using a pilot scale (10 m3/d) test for the advanced treatment of hypersaline petrochemical wastewater in a coastal wastewater plant. The membrane flux and ozone dosage were optimized for the optimal treatment performance of this integrated process. The results showed that this integrated process performed well in pollutant removal. The concentrations of CODCr, phosphate and color in the effluents were 17.9 mg/L, 0.25 mg/L, and 5 dilution times in average, respectively. The effluent quality met the local discharge standard even under a high influent COD concentration (195 mg/L in average). The synergistic effect of the ozonation and ceramic membrane filtration was investigated through the fluorescence characteristics and hydrophobic/hydrophilic properties of organic compounds. It revealed that ozonation mitigated the membrane fouling and the nanopores in the ceramic membranes enhanced the ozonation efficiency. Meanwhile, the Fenton process had a slightly better effluent quality than the integrated process, but Fenton process consumed much more chemicals and required the sludge disposal, resulting in higher cost. The estimated unit cost for this integrated process was only 34% of that for the Fenton process. Overall, the integrated process demonstrated high stability, reliable effluents and low cost, providing a promising and cost-efficient technology for the treatment of hypersaline petrochemical wastewater.