Optimisation of membrane technology for water reuse

Increasing freshwater scarcity is making reclamation of wastewater effluent more economically attractive as a means of preserving freshwater resources. The use of an integrated membrane system (IMS), the combination of micro/ultra-filtration (MF/UF) followed by reverse osmosis (RO) membranes, represents a key process for municipal wastewater reuse. A major drawback of such systems is the fouling of both the MF/UF and RO membranes. The water to be treated by the IMS system varies from one wastewater treatment plant (WWTP) to another, and its fouling propensity changes correspondingly. It is thus preferable to conduct pilot trials before implementing a full-scale plant. This thesis aims to look at the sustainability of IMS technology dedicated to indirect potable reuse (IPR) in terms of fouling minimisation and cost via a 600 m3 .d- 1 pilot plant. Wastewater reuse plants, using IMS, as well as statistical methods for membrane optimisation were reviewed. Box-Behnken design was used to define optimum operating envelopes of the pilot plant for both the microfiltration and the reverse osmosis in terms of fouling minimisation. Same statistical method was used to enhance the efficiency of the MF cleaning-in place through bench-scale test. Data from the pilot plant MF process allow to determine relationship between reversible and irreversible fouling, and operating parameters and feed water quality. Life cycle cost analysis (LCCA) of the both trains (MF/RO/AOP and MF/AOP) of the pilot plant was performed and compared with the LCCA of two full-scale plant

Applying the water safety plan to water reuse: towards a conceptual risk management framework

The Water Safety Plan (WSP) is receiving increasing attention as a recommended risk management approach for water reuse through a range of research programmes, guidelines and standards. Numerous conceptual modifications of the approach – including the Sanitation Safety Plan, the Water Cycle Safety Plan, and even a dedicated Water Reuse Safety Plan – have been put forward for this purpose. However, these approaches have yet to encapsulate the full spectrum of possible water reuse applications, and evidence of their application to reuse remains limited. Through reviewing the existing evidence base, this paper investigates the potential for adapting the WSP into an approach for water reuse. The findings highlight a need for the management of risk to reflect on, and facilitate the inclusion of, broader contexts and objectives for water reuse schemes. We conclude that this could be addressed through a more integrated approach to risk management, encapsulated within an overarching risk management framework (adapted from the WHO's Framework for safe drinking water) and operationalised through the Water Reuse Safety Plan (WRSP). We also propose that the WRSP should be based on modifications to the existing WSP approach, including an increased emphasis on supporting communication and engagement, and improvements in decision support mechanisms to better account for uncertainty, risk interactions and risk prioritisation

A Packed Memory Array to Keep Moving Particles Sorted

International audienceNeighbor identification is the most computationally intensive step in particle based simulations. To contain its cost, a common approach consists in using a regular grid to sort particles according to the cell they belong to. Then, neighbor search only needs to test the particles contained in a constant number of cells. During the simulation, a usually small amount of particles are moving between consecutive steps. Taking into account this temporal coherency to save on the maintenance cost of the acceleration data structure is difficult as it usually triggers costly dynamics memory allocations or data moves. In this paper we propose to rely on a Packed Memory Array (PMA) to efficiently keep particles sorted according to their cell index. The PMA maintains gaps in the particle array that enable to keep particle sorted with O(log2(n)) amortized data moves. We further improve the original PMA data structure to support efficient batch data moves. Experiments show that the PMA can outperform a compact sorted array for up to 50% element moves

Flow cytometry-based evaluation of the bacterial removal efficiency of a blackwater reuse treatment plant and the microbiological changes in the associated non-potable distribution network

The study evaluated the changes in bacterial numbers across a full-scale membrane bioreactor (MBR) blackwater reuse system. Flow cytometry was used to quantify total and intact bacterial concentrations across the treatment train and during distribution of the recycled water. Membrane passage reduced bacterial numbers by up to 5-log units resulting in coliform-free permeate. A 2-log increase in bacterial cell concentration was subsequently observed after the granular activated carbon unit followed by a reduction in intact cells after chlorination, which corresponds to an overall intact bacteria removal of 3.4-log units. In the distribution network, the proportion of intact cells greatly depended on the free chlorine residual, with decreasing residual enabling regrowth. An initial target of 0.5 mg L−1 free chlorine ensured sufficient suppression of intact cells for up to 14 days (setting the time intervals for system flushes at times of low water usage). Bacterial regrowth was only observed when the free chlorine concentration was below 0.34 mg L−1. Such loss of residual chlorine mainly applied to distant points in the distribution network from the blackwater reuse treatment plant (BRTP). Flushing these network points for 5 min did not substantially reduce cell numbers. At points closer to the BRTP, on the other hand, flushing reduced cell numbers by up to 1.5-log units concomitant with a decreasing proportion of intact cells. Intact cell concentrations did not correlate with DOC, total nitrogen, or soluble reactive phosphate, but it was shown that dead biomass could be efficiently converted into new biomass within seven days

A Sensitive Micro Conductometric Ethanol Sensor Based on an Alcohol Dehydrogenase-Gold Nanoparticle Chitosan Composite

In this paper, a microconductometric sensor has been designed, based on a chitosan composite including alcohol dehydrogenase—and its cofactor—and gold nanoparticles, and was calibrated by differential measurements in the headspace of aqueous solutions of ethanol. The role of gold nanoparticles (GNPs) was crucial in improving the analytical performance of the ethanol sensor in terms of response time, sensitivity, selectivity, and reproducibility. The response time was reduced to 10 s, compared to 21 s without GNPs. The sensitivity was 416 µS/cm (v/v%)−1 which is 11.3 times higher than without GNPs. The selectivity factor versus methanol was 8.3, three times higher than without GNPs. The relative standard deviation (RSD) obtained with the same sensor was 2%, whereas it was found to be 12% without GNPs. When the air from the operator’s mouth was analyzed just after rinsing with an antiseptic mouthwash, the ethanol content was very high (3.5 v/v%). The background level was reached only after rinsing with water

Treatment use in a prospective naturalistic cohort of children and adolescents with catatonia

Abstract We aimed to (1) describe the treatment used in a large sample of young inpatients with catatonia, (2) determine which factors were associated with improvement and (3) benzodiazepine (BZD) efficacy. From 1993From to 2011 patients between the ages of 9 and 19 years were consecutively hospitalized for a catatonic syndrome. We prospectively collected sociodemographic, clinical and treatment data. In total, 51 (77 %) patients underwent a BZD trial. BZDs were effective in 33 (65 %) patients, who were associated with significantly fewer severe adverse events (p = 0.013) and resulted in fewer referrals for electroconvulsive therapy (ECT) (p = 0.037). Other treatments included ECT (N = 12, 18 %); antipsychotic medications, mostly in combination; and treatment of an underlying medical condition, when possible. For 10 patients, four different trials were needed to achieve clinical improvement. When all treatments were combined, there was a better clinical response in acute-onset catatonia (p = 0.032). In contrast, the response was lower in boys (p = 0.044) and when posturing (p = 0.04) and mannerisms (p = 0.008) were present as catatonic symptoms. The treatment response was independent of the underlying psychiatric or systemic medical condition. As in adults, BZDs should be the first-line symptomatic treatment for catatonia in young patients, and ECT should be a second option. Additionally, the absence of an association between the response to treatment and the underlying psychiatric condition suggests that catatonia should be considered as a syndrome

Relevance of Brain 18F-FDG PET Imaging in Probable Seronegative Encephalitis With Catatonia: A Case Report

Autoimmune encephalitis (AIE) is a rare, severe, and rapidly progressive encephalopathy, and its diagnosis is challenging, especially in adolescent populations when the presentation is mainly psychiatric. Currently, cerebral 18-fluorodeoxyglucose positron emission tomography (18F-FDG-PET) imaging is not included in the diagnosis algorithm. We describe a 16-year-old patient with probable seronegative encephalitis with catatonia for which several cerebral PET scans were relevant and helpful for diagnosis, treatment decision making, and follow-up monitoring. The patient recovered after 2 years of treatment with etiologic treatment of AIE and treatment of catatonia. This case suggests a more systematic assessment of the clinical relevance of 18F-FDG-PET imaging in probable seronegative AIE

Genetic landscape of a large cohort of Primary Ovarian Insufficiency : New genes and pathways and implications for personalized medicine

Background Primary Ovarian Insufficiency (POI), a public health problem, affects 1-3.7% of women under 40 yield-ing infertility and a shorter lifespan. Most causes are unknown. Recently, genetic causes were identified, mostly in single families. We studied an unprecedented large cohort of POI to unravel its molecular pathophysiology.Methods 375 patients with 70 families were studied using targeted (88 genes) or whole exome sequencing with pathogenic/likely-pathogenic variant selection. Mitomycin-induced chromosome breakages were studied in patients' lymphocytes if necessary. Findings A high-yield of 29.3% supports a clinical genetic diagnosis of POI. In addition, we found strong evidence of pathogenicity for nine genes not previously related to a Mendelian phenotype or POI: ELAVL2, NLRP11, CENPE, SPATA33, CCDC150, CCDC185, including DNA repair genes: C17orf53(HROB), HELQ, SWI5 yielding high chromo-somal fragility. We confirmed the causal role of BRCA2, FANCM, BNC1, ERCC6, MSH4, BMPR1A, BMPR1B, BMPR2, ESR2, CAV1, SPIDR, RCBTB1 and ATG7 previously reported in isolated patients/families. In 8.5% of cases, POI is the only symptom of a multi-organ genetic disease. New pathways were identified: NF-kB, post-translational regulation, and mitophagy (mitochondrial autophagy), providing future therapeutic targets. Three new genes have been shown to affect the age of natural menopause supporting a genetic link.Interpretation We have developed high-performance genetic diagnostic of POI, dissecting the molecular pathogene-sis of POI and enabling personalized medicine to i) prevent/cure comorbidities for tumour/cancer susceptibility genes that could affect life-expectancy (37.4% of cases), or for genetically-revealed syndromic POI (8.5% of cases), ii) predict residual ovarian reserve (60.5% of cases). Genetic diagnosis could help to identify patients who may benefit from the promising in vitro activation-IVA technique in the near future, greatly improving its success in treating infertility.Funding Universite? Paris Saclay, Agence Nationale de Biome?decine.Copyright (c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Peer reviewe

Synthèse et utilisation de copolymères amphiphiles incorporant des unités alcool vinylique en tant que stabilisant pour la copolymérisation en émulsion de l'acétate de vinyle

Les copolymères de type poly[(alcool vinylique)-co-(acétate de vinyle)] P(VOH-s-VAc) sont obtenus par alcoolyse partielle du poly(acétate de vinyle) (PAcV). Ces macromolécules trouvent des applications dans des domaines variés, et sont en particulier très utilisées comme stabilisants dans la (co)polymérisation en émulsion de l’acétate de vinyle (AcV). Cependant, au cours du procédé de polymérisation en émulsion, toutes les chaines de P(VOH-s-VAc) ne sont pas impliquées dans la stabilisation des particules. Celles-ci se retrouvent dans la phase aqueuse en fin de polymérisation et ont un impact négatif sur les propriétés finales du produit. Le but de ce projet de recherche est donc de synthétiser de nouvelles structures de copolymères amphiphiles incorporant des unités VOH, qui soient capables de répondre aux problèmes associés à l’utilisation de P(VOH-s-VAc) conventionnels dans la synthèse de latex à base d’acétate de vinyle (AcV).La polymérisation radicalaire contrôlée par transfert de chaine réversible par addition-fragmentation (RAFT) a largement été utilisée dans la littérature pour accéder à des architectures contrôlées, bien définies et diverses telles que des copolymères à blocs. Après avoir sélectionné le néodécanoate de vinyle (VeoVa) et le laurate de vinyle (VL) comme comonomères de l’AcV, et réalisé les copolymérisations correspondantes à l’aide du procédé RAFT, l’hydrolyse sélective des unités AcV dans les copolymères bien définis obtenus a été évaluée. Le pouvoir stabilisant des copolymères amphiphiles résultant de l’hydrolyse a été testé dans un système de copolymérisation en émulsion de l’AcV et VeoVa.Les structures présentant les meilleurs résultats en termes de stabilité des latexes et en termes d’adsorption et greffage sur les particules, ont ensuite été synthétisées à plus grande échelle chez WACKER pour y être testées dans des domaines d’applications variés.Poly(vinyl alcohol-co-vinyl acetate) ((PVOH-s-VAc)) copolymers obtained by partial alcoholysis of poly(vinyl acetate) (PVAc) are of practical importance for many applications, including as stabilizers for emulsion copolymerization of vinyl acetate (VAc). In the latter case, the obtained products can be used either as a latex or as a re-dispersible powder after spray drying and find applications in various fields such as e.g., adhesives, binders, medical applications or paints. However, during the emulsion process, all the P(VOH-s-VAc) chains are not involved in the stabilization of the particles. Indeed, free P(VOH-s-VAc) chains can be found in the aqueous phase, which can impact the properties of the end-products. The present project aims to synthesize new amphiphilic copolymers incorporating VOH units, that are able (i) to stabilize VAc-based latexes with a better involvement in the stabilization of the particles, and (ii) to circumvent the potential problems resulting from remaining water-soluble chains encountered when the final polymer product is processed. The synthesis of the targeted amphiphilic copolymers relies on reversible addition-fragmentation chain transfer (RAFT) polymerization that allows the formation of well-defined polymer architectures. A careful design of copolymers of VAc and vinylic ester comonomers (CoM) was first performed to access a range of copolymer structures, including block copolymers. As CoM, vinyl neodecanoate (VeoVa) and vinyl laurate (VL) were chosen and hydrolysis conditions that could be selective of the VAc units were identified. After hydrolysis, the resulting well-defined amphiphilic copolymer structures were evaluated as stabilizers in the emulsion copolymerization of VAc and VeoVa.The structures presenting the best results in terms of latex stability and of adsorption efficiency and grafting onto the particles were then synthesized on a larger scale at WACKER to be tested in various fields of applications