Factors Associated with Spontaneous Preterm Birth after Ultrasound-Indicated Cerclage.

Ultrasound-indicated cerclage (UIC) is recommended to prevent spontaneous preterm birth (sPTB) in women with a short cervix at mid-trimester and a history of PTB. We assessed the factors related to sPTB after UIC and determined the corresponding risks. This retrospective cohort study was conducted at a university hospital. UIC was performed between 15 and 26 weeks of gestation in women with a cervical length of <2.5 cm. Univariate and multivariate analyses were used to examine factors associated with sPTB after UIC. An earlier gestational age and shorter cervical length at UIC were associated with sPTB after UIC. While PTB history was not associated with an increased risk of sPTB, it did increase the risk of repeat cerclage after UIC. Higher levels of preoperative serum inflammatory markers and obesity significantly increased the risk of sPTB after UIC. These findings provide helpful guidance for patient counseling and management in predicting the delivery timing after UIC in women with a short cervix in the mid-trimester.

Danazol as a Treatment for Uterine Arteriovenous Malformation: A Case Report.

Uterine arteriovenous malformation (AVM) is associated with a risk of massive uterine bleeding. Although uterine artery embolization remains the first-line treatment for AVM, there has been a recent exploration of pharmacological options. Danazol is known to reduce blood flow to the uterus; however, our understanding of its therapeutic efficacy for AVM remains limited. Herein, we present the results of danazol use in patients with uterine AVM. We retrospectively reviewed the medical records of patients who received danazol for the treatment of AVM between January 2013 and November 2022. The cohort comprised 10 patients who developed AVM after dilatation and curettage (D&C), abortion, or cesarean section. Danazol was administered twice daily at a total dose of 400 mg/day, and was employed for AVM treatment in hemodynamically stable patients who provided consent and were devoid of massive bleeding. Outpatient follow-ups (ultrasound measurements of AVM size and symptom assessment) were performed every 2 weeks. AVM was successfully treated with danazol in most patients with no adverse event. Eight postabortal patients had complete resolution of AVM after an average of 45 days (range 14-70 days). Of two patients who developed AVM after a cesarean section, one experienced AVM reduction, and the other developed massive bleeding, requiring emergency uterine artery embolization. In light of these outcomes, danazol can be potentially prioritized over uterine artery embolization in the treatment of AVM after abortion in hemodynamically stable patients.

Postoperative cervical length to predict success of repeat cerclage in singleton pregnancies with prolapsed membranes after prior cerclage.

Background: This study aimed to evaluate the outcome of repeat cerclage (RC) in singleton pregnancies with prolapsed membranes following a prior cerclage and analyze predictive factors for delivery at ≥26 weeks of gestation following RC. Materials and methods: Patients who underwent RC between 2010 and 2020 at the Hallym University Medical Center were reviewed. Women with singleton pregnancies with prolapsed membranes following prior cerclage were candidates for RC. We analyzed the characteristics, pregnancy outcomes, perioperative clinical and laboratory findings, and postoperative cervical length (CL) to identify the factors for predicting delivery at ≥26 weeks following RC. Results: Thirty-five women with RC were identified; the median gestational age (GA) at a prior cerclage was 14 weeks, the average GA at RC was 21 + 3 weeks, and the median GA at delivery following RC was 26 + 2 weeks. Patients were divided into two groups based on their delivery status at 26 weeks: 17 women delivered at <26 weeks (range, 18 + 4-25 + 6 weeks) (Group A) and 18 women delivered at ≥26 weeks (range, 26 + 2-40 + 3 weeks) (Group B). The median GA at delivery in group A was 22 + 4 weeks, whereas that in group B was 33 + 4 weeks (p < 0.001). No differences in preoperative clinical and laboratory findings were observed between the two groups. However, the postoperative CL in group A was significantly shorter than that in group B (12 mm vs. 21.5 mm, p < 0.001). The ROC curve of postoperative CL predicting delivery at ≥26 weeks showed an AUC of 0.843; a CL of 20 mm showed a sensitivity of 61.1% and a specificity of 100%. Conclusion: RC may prolong singleton pregnancies with prolapsed membranes following prior cerclage. A postoperative CL ≥20 mm may predict the success of RC.

Immune-checkpoint proteins, cytokines, and microbiome impact on patients with cervical insufficiency and preterm birth.

Background: Microenvironmental factors, including microbe-induced inflammation and immune-checkpoint proteins that modulate immune cells have been associated with both cervical insufficiency and preterm delivery. These factors are incompletely understood. This study aimed to explore and compare interactions among microbiome and inflammatory factors, such as cytokines and immune-checkpoint proteins, in patients with cervical insufficiency and preterm birth. In particular, factors related to predicting preterm birth were identified and the performance of the combination of these factors was evaluated. Methods: A total of 220 swab samples from 110 pregnant women, prospectively recruited at the High-Risk Maternal Neonatal Intensive Care Center, were collected between February 2020 and March 2021. This study included 63 patients with cervical insufficiency receiving cerclage and 47 control participants. Endo- and exocervical swabs and fluids were collected simultaneously. Shotgun metagenomic sequencing for the microbiome and the measurement of 34 immune-checkpoint proteins and inflammatory cytokines were performed. Results: First, we demonstrated that immune-checkpoint proteins, the key immune-regulatory molecules, could be measured in endocervical and exocervical samples. Secondly, we identified significantly different microenvironments in cervical insufficiency and preterm birth, with precise cervical locations, to provide information about practically useful cervical locations in clinical settings. Finally, the presence of Moraxella osloensis (odds ratio = 14.785; P = 0.037) and chemokine CC motif ligand 2 levels higher than 73 pg/mL (odds ratio = 40.049; P = 0.005) in endocervical samples were associated with preterm birth. Combining M. osloensis and chemokine CC motif ligand 2 yielded excellent performance for predicting preterm birth (area under the receiver operating characteristic curve = 0.846, 95% confidence interval = 0.733-0.925). Conclusion: Multiple relationships between microbiomes, immune-checkpoint proteins, and inflammatory cytokines in the cervical microenvironment were identified. We focus on these factors to aid in the comprehensive understanding and therapeutic modulation of local microbial and immunologic compositions for the management of cervical insufficiency and preterm birth.

Risk factors based on myoma characteristics for predicting postoperative complications following cesarean myomectomy.

OBJECTIVES: To evaluate the influence of myoma characteristics on cesarean myomectomy and to demonstrate its additional advantages. METHODS: Retrospective data were collected from 292 women with myomas who had undergone cesarean section at Kangnam Sacred Heart Hospital between 2007 and 2019. We performed subgroup analysis according to the type, weight, number, and size of myomas. Preoperative and postoperative hemoglobin levels, operative time, estimated blood loss, length of hospital stay, incidence of transfusion, uterine artery embolization, ligation, hysterectomy, and postoperative complications were compared among subgroups. RESULTS: There were 119 patients who had cesarean myomectomy and 173 who had cesarean section only. An increase in postoperative hospitalization and operation time was observed in the cesarean myomectomy group compared to that in the caesarean section only group (mean difference, 0.7 days, p = 0.01, 13.5 minutes, p <0.001). Estimated blood loss, hemoglobin differences, and transfusion rates were higher in the cesarean myomectomy than in the cesarean section only group. There were no differences in postoperative complications (fever, bladder injury, and ileus) between the two groups. No hysterectomy cases were reported in the cesarean myomectomy group. In subgroup analysis, the larger and heavier the myoma, the higher the risk of bleeding that led to transfusion. Estimated blood loss, differences in hemoglobin, and transfusion rate increased depending on myoma size and weight. A significant increase in postoperative hospitalization was observed in women with larger and heavier myomas. However, there was no statistical difference among the three types of myomas. CONCLUSION: In cesarean myomectomy, larger (≥ 10 cm), and heavier myomas (≥ 500 g), were associated with postoperative outcomes, but not the number or type of myoma. The safety of cesarean myomectomy is not inferior to that of caesarean section only, considering its positive effects such as gynecological symptom relief and avoidance of the next surgery.

Immobilization of 137Cs as a crystalline pollucite surrounded by amorphous aluminosilicate.

To date, radiocesium (137Cs) has been considered stable in the form of pollucite mineralized through high-temperature heat treatment. This study presented a possibility through experimental results that the entire medium exists as amorphous aluminosilicate at a relatively low temperature, but cesium is partially and preferentially converted from a composite adsorbent into pollucite. Cesium lowers the eutectic point within the system and initiates the nucleation of pollucite prior to other elements. We confirmed that the partial mineral phase of cesium showed the same chemical stability as when the entire medium was converted to pollucite. X-ray absorption spectroscopy provided direct evidence for this phenomenon; also, the stability results of radioactive cesium shown through a series of sintering experiments supported the conclusion. This method can be applied as a method to immobilize radioactive cesium under relatively mild temperature conditions of atmospheric pressure, while eliminating the problem of diffusion due to its volatilization.

Ultrasound-Indicated Cerclage in Twin Pregnancies: A Cohort Study.

Background: To report the pregnancy and neonatal outcomes in patients with twin pregnancies who underwent ultrasound-indicated cerclage (UIC) and to compare them to patients with singleton pregnancies undergoing the same procedures. Methods: Patients who underwent UIC between January 2010 and December 2020 at Kangnam Sacred Heart Hospital were reviewed. We compared characteristics, pregnancy, and neonatal outcomes between patients with singleton and twin pregnancies. Results: A total of 94 women (56 singleton and 38 twin pregnancies) underwent UIC were included. The mean gestational age (GA) at cerclage and preoperative cervical length (CL) were not significantly different. Twin pregnancies were more likely to deliver at earlier median gestations than singletons (singleton, 36 + 1 weeks vs twin, 32 + 6 weeks, and p = 0.004). The frequency of preterm delivery <34 weeks in twin group was higher than in singleton group (15 (26.8%) vs 20 (52.6%) and p =0.016). However, the frequency of preterm delivery <32, <28, and <24 weeks was not significantly different between two groups. Although neonatal weights in singleton pregnancies were heavier than twin pregnancies, neonatal mortality and morbidities were not significantly different between two groups. Among various factors contributing to preterm birth, preoperative CL ≤ 15 mm was independently associated with a higher risk of preterm delivery before 34 weeks. Furthermore, pregnancy and neonatal outcomes of twin pregnancies with cervical length ≤ 15 mm are comparable with those of singleton pregnancies (GA at delivery, singleton, 35 + 1 weeks vs twin, 32 + 5 weeks, and p = 0.24; neonatal mortality, singleton, 3.4% vs twin, 4.8%, and p = 0.64). Conclusion: The pregnancy and neonatal outcomes of UIC in twin pregnancies were comparable to those in singleton pregnancies, especially when CL is ≤15 mm. UIC might be considered a safe procedure for twin pregnancies.

Expression of antimicrobial peptides in the amniotic fluid of women with cervical insufficiency.

PROBLEM: Cervical insufficiency (CI) is associated with intra-amniotic infection or inflammation. Antimicrobial peptides (AMPs) in amniotic fluid may protect the fetus against microbial invasion, giving their broad-spectrum microbiocidal properties. We evaluated changes in amniotic fluid AMP expression in women with CI and assessed whether these changes are related to their pregnancy outcomes. METHOD OF STUDY: We evaluated amniotic fluid human neutrophil peptide 3 (HNP-3), human ß-defensin-2 (hBD-2), and LL-37 levels in 66 women with CI and 25 normal controls at 16-24 weeks of gestation. The CI group was divided into short cervix and cervical dilation groups, and the cervical dilation group was further divided into preterm and full-term delivery groups according to the pregnancy outcomes, and AMP expression was analyzed in each group. RESULTS: HNP-3 and hBD-2 levels were higher in women with CI than in normal controls and in the cervical dilation as compared to the short cervix group. Among women with cervical dilation, 22 delivered at full-term, and 23 had spontaneous preterm births. The hBD-2 level in amniotic fluid mid-pregnancy was higher in the full-term delivery than in the preterm delivery groups. However, LL-37 levels in amniotic fluid were low in women with CI and normal controls. CONCLUSIONS: Amniotic fluid HNP-3 and hBD-2 levels increased in women with CI compared with normal controls. Moreover, increased amniotic fluid hBD-2 levels mid-pregnancy were associated with favorable pregnancy outcomes in women with CI. AMPs in the amniotic fluid may participate in host defense against ascending infection in women with CI.

The Role of Antimicrobial Peptides in Preterm Birth.

Antimicrobial peptides (AMPs) are short cationic amphipathic peptides with a wide range of antimicrobial properties and play an important role in the maintenance of immune homeostasis by modulating immune responses in the reproductive tract. As intra-amniotic infection and microbial dysbiosis emerge as common causes of preterm births (PTBs), a better understanding of the AMPs involved in the development of PTB is essential. The altered expression of AMPs has been reported in PTB-related clinical presentations, such as preterm labor, intra-amniotic infection/inflammation, premature rupture of membranes, and cervical insufficiency. Moreover, it was previously reported that dysregulation of AMPs may affect the pregnancy prognosis. This review aims to describe the expression of AMPs associated with PTBs and to provide new perspectives on the role of AMPs in PTB.

Content Analysis and Quality Evaluation of Cesarean Delivery-Related Videos on YouTube: Cross-sectional Study.

BACKGROUND: YouTube is one of the most popular open-access video-sharing websites, and it is also used to obtain health care information. Cesarean delivery is the most common major surgical intervention in many countries. Videos related to cesarean delivery have also been uploaded to YouTube. However, no study has explored the overall quality of cesarean delivery videos on the platform. OBJECTIVE: The objective of this study was to analyze the content and evaluate the quality of the most frequently viewed videos related to cesarean delivery that are accessible on YouTube. METHODS: We searched for a total of 18 terms by combining the 6 terms retrieved from Google AdWords and the 3 terms c section, cesarean section, and cesarean delivery, which are used interchangeably. Videos were sorted by view count, and the 100 videos with the highest view counts were chosen. The number of views, duration, likes and dislikes, content type, and source of each video were recorded. In evaluating the quality of the videos, we referred to a previous study. Additionally, we developed a detailed scoring method that comprehensively evaluates the videos related to cesarean delivery by including the necessary information for each element of the cesarean delivery and whether scientific evidence was presented. RESULTS: Of the 100 videos analyzed, the most prevalent content (n=28) was videos that contained the actual surgical procedure of a cesarean delivery, and the most common source of cesarean delivery videos was physicians (n=30). Videos directly related to cesarean delivery, such as explanation of the surgery and the actual surgical procedure, were mainly uploaded by medical groups and scored higher than the videos indirectly related to cesarean delivery, which were mainly uploaded by nonmedical groups. In addition, videos directly related to cesarean delivery were more often uploaded earlier in time, with lower like ratios compared to indirect videos. CONCLUSIONS: YouTube is currently not an appropriate source for patients seeking information on cesarean delivery.

Whole blood RNA sequencing reveals a differential transcriptomic profile associated with cervical insufficiency: a pilot study.

BACKGROUND: The uterine cervix is a mechanical and immunological barrier against ascending infection during pregnancy. Cervical insufficiency (CI), a painless cervical dilation that occurs in the mid-trimester, is an important cause of extremely preterm birth. We hypothesized that women with CI have a differential transcriptomic profile. Therefore, we compared the transcriptomic profile of peripheral blood in women with CI and that of controls. METHODS: RNA sequencing was used to generate the global gene expression profiles of 11 women with CI and 4 controls, and differential expression analysis was performed to identify genes showing significant expression changes between the CI (n = 11) and control (n = 4) groups as well as between the CI-preterm (n = 7) and CI-term (n = 4) groups. Gene set enrichment was assessed in terms of Gene Ontology processes, and a subset of differentially expressed genes in CI was validated in a different sample-set by qRT-PCR and ELISA. RESULTS: Thirty genes were differentially expressed between the CI and control groups. Differentially upregulated genes in the CI group included neutrophil-mediated immunity-associated (DEFA3 and ELANE) and bicarbonate transport-related genes. The serum concentration of alpha defensin 3 was significantly higher in women with CI than in controls (P = 0.014). Analysis of differential gene expression according to pregnancy outcomes revealed 338 differentially expressed genes between the CI-term and CI-preterm groups. Immune and defense response to organism-associated genes and influenza A and NOD-like receptor signaling pathways were upregulated in the CI-term group. CONCLUSIONS: Our results revealed significant differences in the whole blood transcriptomic profiles of women with CI compared to those of controls. Different immune responses in women with CI may affect pregnancy outcomes.

Concurrent occurrence of electrochemical dissolution/deposition of cobalt-calcium phosphate composite.

Amorphous cobalt-calcium phosphate composite (CCPC) films are electrochemically prepared on various electrodes by utilizing the solid phase of hydroxyapatite as a phosphate source. The CCPC film formation is surface process in which the dissolution of hydroxyapatite and the deposition of CCPC film concurrently occur on the electrode surface without the mass transfer of phosphate ions into the bulk solution. Elemental, crystallographic, and morphological analyses (EDX, ICP-AES, XPS, and XRD) indicate that the CCPC is composed of amorphous cobalt oxide with calcium and phosphate. The film exhibits durable oxygen evolution reaction (OER) catalytic properties under neutral and basic aqueous condition. Compared to using solution phase of phosphate source, our preparation method utilizing solid hydroxyapatite has advantage of preventing unnecessary chemical reaction between phosphate and other chemical species in bulk solution.

Effective removal of radioactive cesium from contaminated water by synthesized composite adsorbent and its thermal treatment for enhanced storage stability.

A composite adsorbent for the removal of radioactive cesium (137Cs) was synthesized by immobilizing potassium cobalt ferrocyanide in the micro pores of the zeolite chabazite. The synthetically optimized composite adsorbent demonstrates a rapid cesium adsorption rate under both salt-free and high-salt conditions with a high distribution coefficient of cesium (≥105 mL/g). Although both components have the same ion-exchange reaction between potassium and cesium, the reaction by ferrocyanide component was predominant, which derived hundred times higher distribution coefficient of the composite adsorbent than that of pure chabazite. A thermal stabilization process was studied for improving the storage and/or disposal stability of the spent adsorbent. The formation of a eutectic system within the spent adsorbent reduced the stabilization temperature to 1000 °C from 1200 °C. Accordingly, the leaching of cesium was remarkably reduced by the remineralization to the stable pollucite. The stable impregnation of ferrocyanide component in the chabazite pores derived the reduction of cesium volatility enabling the high temperature stabilization method. Our experimental results provide evidence that the composite adsorbent has clear advantages on the cesium removal from contaminated water and its stabilization via thermal-treatment.

Application of Desalination Membranes to Nuclide (Cs, Sr, and Co) Separation.

Desalination and nuclide separation, with cesium (Cs), strontium (Sr), and cobalt (Co), using commercial polymeric membranes are investigated under room temperature (298 K) to elucidate the permeation mechanism and possibility of applying commercial membranes to the separation of radioactive nuclides. The physicochemical properties of membranes are characterized by multiple techniques. The thickness of the selective layer and the boundary between the layers of membranes are observed by scanning electron microscopy. The chemical structure of selective and support layers is assessed by direct Fourier transform infrared/attenuated total reflection measurements on membrane samples. Thermogravimetric analysis demonstrates the composition comparison between membranes, which describes the relative amount of selective layers consisting of polyamide. The separation performance of polyamide-based commercial membranes is tested on simulated seawater (35,000 ppm of NaCl) and single- and multi-component aqueous nuclide solutions (10 ppm). Nanofiltration (NF) membranes exhibit a high flux of 160-210 L m-2 h-1 with low 31-64% rejection on the permeation of simulated seawater, while reverse osmosis (RO) membranes display a low flux of 13-22 L m-2 h-1 with nearly 80% rejection. This reveals RO membranes to be more effective for the rejecting nuclides (Cs, Sr, and Co) in dilute aqueous solutions, and NF membranes have advantage on high throughput. RO membranes reject above 93% for single components and even higher for mixed nuclide separation (>98%), and NF membranes permeate high flux above 230 L m-2 h-1. This study indicates that the desalination membranes (NF and RO) can be potential candidates for nuclide separation with combination.

Outcomes after transabdominal cerclage in twin pregnancy with previous unsuccessful transvaginal cerclage.

Transabdominal cerclage (TAC) is reported to be effective for preventing preterm birth in women with unsuccessful transvaginal cerclage (TVC) history. However, TAC has rarely been performed in twin pregnancy given the lack of sufficient evidence and the technical difficulty of the operation. Thus, it is unclear whether TAC is an effective procedure for twin pregnancy in women with a history of unsuccessful TVC. The aim of this study is to compare the characteristics and pregnancy outcomes after TAC in twin pregnancy versus singleton pregnancy, to examine whether twin pregnancy is a risk factor for very preterm birth (before 32 weeks) after TAC, and to determine whether TAC is effective in preventing preterm birth in twin pregnancy. This single-center retrospective cohort study included women who underwent TAC because of unsuccessful TVC history between January 2007 and June 2018. Of 165 women who underwent TAC, 19 had twins and 146 had singletons. Our results showed that the neonatal survival rate improved dramatically when TAC was performed (15.4% (prior pregnancy) vs 94.0% (after TAC) in twins, p<0.01; 22.8% (prior pregnancy) vs 91.1% (after TAC) in singletons, p<0.01). Moreover, the risk of very preterm birth was significantly decreased after TAC in both groups (36/39 (92.3%) (prior pregnancy) vs 2/19 (10.5%) (after TAC) in twins, p<0.01; 290/337 (86.1%) (prior pregnancy) vs 17/146 (11.6%) (after TAC) in singletons, p<0.01). More advanced maternal age and history of prior preterm delivery between 26+0 and 36+6 weeks were independently associated with very preterm birth, whereas the presence of a twin pregnancy was not associated with very preterm birth on multivariate logistic regression analysis. These results suggest that TAC is associated with successful prevention of very preterm birth and improved neonatal survival rates in the absence of procedure-related major complications in women with twin pregnancy and previous unsuccessful TVC history.

Pilot-Scale Treatment of a Spent Uranium Catalyst Formally Used in the SOHIO Process: Pilot Plant Verification of the SENSEI Process.

Approximately 7000 drums of waste uranium catalyst are currently present in Korea and require an appropriate treatment and waste management strategy. Recently, one such process has been developed and has proven successful at both laboratory and bench scales. The success of the process has culminated in its verification at a pilot plant scale. The purpose of this paper is to describe the catalyst treatment process and present results obtained from the pilot plant study that may be applicable to other such wastes. The individual unit technologies have been tested and verified, enabling process scale-up to be successfully proven. The final volume reduction of up to 80% has been confirmed with the successful separation, encapsulation, and immobilization of residue wastes, representing a potential cost saving of US$70 million compared to the direct disposal. The inactive silica component of the waste catalyst was purified and confirmed to be free of uranium. All effluents generated during the process were treated and satisfy the appropriate Korean release criteria. The process employs the concept of Selective Extraction of Nonradioactive Species, Encapsulation, and Immobilization, and is therefore introduced as the SENSEI process.

Successful heterotopic pregnancy with prior radical trachelectomy after transabdominal cervico isthimic cerclage with methotrexate treatment.

Heterotopic pregnancy with cervical incompetence is very uncommon. And yet there is no definite treatment for cervical incompetence occurring after radical trachelectomy. We are reporting a rare and novel case of a following in vitro fertilization combined intrauterine pregnancy and interstitial pregnancy which was successfully treated with maintenance of the pregnancy to term.

MicroRNA-548 regulates high mobility group box 1 expression in patients with preterm birth and chorioamnionitis.

High mobility group box 1 (HMGB1) is a prototypic alarmin and plays an important role in the pathogenesis of inflammatory process in spontaneous preterm birth. This study was conducted to compare the levels of HMGB1 in amniotic fluid and amnion membranes in women with chorioamnionitis/intra-amniotic inflammation to the levels in healthy controls. We also aimed to elucidate the involvement of microRNA-548 (miR-548) in regulating HMGB1 expression and its function in human amniotic epithelial cells (hAECs). A bioinformatics analysis predicted the binding of HMGB1 by the miR-548 cluster. A repressed and forced expression assay in hAECs was performed to investigate the causal relationship between the miR-548 cluster and HMGB1. The levels of HMGB1 in amniotic fluid and amnion membranes were significantly higher in patients with intra-amniotic inflammation/chorioamnionitis than in those without inflammation. The miR-548 was significantly under-expressed in amnion membranes from patients with chorioamnionitis than in normal term controls. Repressed expression of miR-548 up-regulated HMGB1 expression in hAECs and increased its release from hAECs. Moreover, forced expression of miR-548 suppressed HMGB1 and inflammatory cytokines in hAECs, which increased when treated with lipopolysaccharide. These results suggest miR-548 can alter the inflammatory responses in hAECs, and might be involved in the pathogenesis of preterm birth by regulating HMGB1.

Antimony(III/V) removal from industrial wastewaters: treatment of spent catalysts formally used in the SOHIO acrylonitrile process.

A treatment and volume reduction process for a spent uranium-antimony catalyst has been developed. Targeted removal, immobilization and disposal of the uranium component has been confirmed, thus eliminating the radiological hazard. However, significant concentrations of antimony ([Sb] ≥ 25-50 mg L-1) remain in effluent from the process, which require removal in compliance with Korean wastewater regulations. Antimony(III/V) removal via co-precipitation with iron has been considered with optimal pH, dose and kinetics being determined. The effect of selected anions - Cl-, SO4 2- and PO4 3- - have also been considered, the latter present due to a prior uranium removal step. Removal of Sb(III) from both Cl- and SO4 2- media and Sb(V) removal from Cl- media to below release limits were found to be effective within 5 minutes at an iron dose of 8 mM (molar ratio, [FeIII]/[Sb] = 20) and a target pH of 5.0. However, Sb(V) removal from SO4 2- was significantly hampered requiring significantly higher iron dosages for the same removal performance. Phosphate poses significant challenges for the removal of Sb(V) due to competition between PO4 3- and Sb(OH)6 - species for surface binding sites, attributed to similarities in chemistries and a shared preference for an inner vs outer binding mechanism.

Effective removal of uranium via phosphate addition for the treatment of uranium laden process effluents.

We have investigated the suitability of phosphate addition, in the form MH2PO4 (M = Na+, K+ or NH4+), for the selective removal of uranium from a complex waste effluent. The effluent in question is generated as part of a treatment strategy for a spent uranium catalyst, used in the production of acrylonitrile (Sohio process), which has been in temporary storage in Korea since 2004. Both pH (3.0-11.0) and phosphate dosages (0.25-10 mM) have been screened to identify the optimal conditions of 6.25 and 1 mM, respectively, for an initial uranium concentration of 0.16 mM. Precipitation kinetics have been investigated revealing the rapid removal of uranium from solution, with 30 min found to be optimal. The effluent was effectively decontaminated via Meta-ankoleite (K(UO2)(PO4)·3H2O) formation to uranium levels below the Korean release limit of 1 ppm for uranium-bearing liquid wastes, with KH2PO4 addition being chosen for the real process. Final decontamination factors of the order of ≥ 8000 were readily achieved. Aluminium, calcium and iron containing coagulants were screened for the clean-up of the remaining supernatant, post-uranium removal, ensuring the final effluent meets the relevant release criteria (pH, total suspended solids, total phosphate and turbidity) for general, non-radioactive, effluents. A process scheme is presented and discussed for adaptation to similar uranium containing effluents.